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Sample records for 3d woven composite

  1. Modeling of 3D Woven Composites Containing Multiple Delaminations

    DTIC Science & Technology

    2012-08-20

    researchers 3D woven composites shows better damage tolerance than laminated textile composites without z-yarns such as plain woven composites even...modeling of quasi-static short beam shear test of plain woven laminated composites. Cohesive elements were used in regions where transverse cracks and...Title ABSTRACT In this paper we present FE modeling of quasi-static short beam shear test of plain woven laminated composites. Cohesive elements were

  2. Impact Damage of 3D Orthogonal Woven Composite Circular Plates

    NASA Astrophysics Data System (ADS)

    Ji, Changgan; Sun, Baozhong; Qiu, Yiping; Gu, Bohong

    2007-11-01

    The damages of 3D orthogonal woven composite circular plate under quasi-static indentation and transverse impact were tested with Materials Test System (MTS) and modified split Hopkinson bar (SHPB) apparatus. The load vs. displacement curves during quasi-static penetration and impact were obtained to study the energy absorption of the composite plate. The fluctuation of the impact stress waves has been unveiled. Differences of the load-displacement curves between the quasi-static and impact loading are discussed. This work also aims at establishing a unit-cell model to analyze the damage of composites. A user material subroutine which named VUMAT for characterizing the constitutive relationship of the 3-D orthogonal woven composite and the damage evolution is incorporated with a finite element code ABAQUS/Explicit to simulate the impact damage process of the composite plates. From the comparison of the load-displacement curves and energy absorption curves of the composite plate between experimental and FEM simulation, it is shown that the unit-cell model of the 3D woven composite and the VUMAT combined with the ABAQUS/Explicit can calculate the impact responses of the circular plate precisely. Furthermore, the model can also be extended to simulate the impact behavior of the 3D woven composite structures.

  3. Modeling the Properties of 3D Woven Composites

    NASA Technical Reports Server (NTRS)

    Cox, Brian N.

    1995-01-01

    An extensive study has been completed of the internal geometry, the mechanisms of failure, and the micromechanics of local failure events in graphite/epoxy composites with three dimensional (3D) woven reinforcement. This work has led to the development of models for predicting elastic constants, strength, notch sensitivity, and fatigue life. A summary is presented here.

  4. Modeling of 3-D Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Sullivan, Roy M.; Mital, Subodh K.

    2003-01-01

    Three different approaches are being pursued at the NASA Glenn Research Center to predict the nanostructural behavior of three-dimensional woven ceramic matrix composites. These are: a micromechanics-based approach using W-CEMCAN (Woven Ceramic Matrix Composite Analyzer), a laminate analogy method and a structural frame approach (based on the finite element method). All three techniques are applied to predict the thermomechanical properties of a three-dimensional woven angle interlock C/SiC composite. The properties are predicted for room temperature and 1100 C and the predicted properties are compared to measurements. General observations regarding the three approaches for three-dimensional composite modeling are discussed.

  5. Influence of Fibre Architecture on Impact Damage Tolerance in 3D Woven Composites

    NASA Astrophysics Data System (ADS)

    Potluri, P.; Hogg, P.; Arshad, M.; Jetavat, D.; Jamshidi, P.

    2012-10-01

    3D woven composites, due to the presence of through-thickness fibre-bridging, have the potential to improve damage tolerance and at the same time to reduce the manufacturing costs. However, ability to withstand damage depends on weave topology as well as geometry of individual tows. There is an extensive literature on damage tolerance of 2D prepreg laminates but limited work is reported on the damage tolerance of 3D weaves. In view of the recent interest in 3D woven composites from aerospace as well as non-aerospace sectors, this paper aims to provide an understanding of the impact damage resistance as well as damage tolerance of 3D woven composites. Four different 3D woven architectures, orthogonal, angle interlocked, layer-to-layer and modified layer-to-layer structures, have been produced under identical weaving conditions. Two additional structures, Unidirectional (UD) cross-ply and 2D plain weave, have been developed for comparison with 3D weaves. All the four 3D woven laminates have similar order of magnitude of damage area and damage width, but significantly lower than UD and 2D woven laminates. Damage Resistance, calculated as impact energy per unit damage area, has been shown to be significantly higher for 3D woven laminates. Rate of change of CAI strength with impact energy appears to be similar for all four 3D woven laminates as well as UD laminate; 2D woven laminate has higher rate of degradation with respect to impact energy. Undamaged compression strength has been shown to be a function of average tow waviness angle. Additionally, 3D weaves exhibit a critical damage size; below this size there is no appreciable reduction in compression strength. 3D woven laminates have also exhibited a degree of plasticity during compression whereas UD laminates fail instantly. The experimental work reported in this paper forms a foundation for systematic development of computational models for 3D woven architectures for damage tolerance.

  6. Nonlinear Multiscale Modeling of 3D Woven Fiber Composites under Ballistic Loading

    DTIC Science & Technology

    2013-07-11

    advanced composites like 3D -OWC. On the other hand, a microscale simulation with resolution of individual fiber filament is impractical due to enormous...REPORT Nonlinear Multiscale Modeling of 3D Woven Fiber Composites under Ballistic Loading 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: The objective of...analysis of 3D woven fiber composites under ballistic loading. Since material behavior is determined by its microstructure, it is essential to

  7. Compressive Behavior of 3D Woven Composite Stiffened Panels: Experimental and Numerical Study

    NASA Astrophysics Data System (ADS)

    Zhou, Guangming; Pan, Ruqin; Li, Chao; Cai, Deng'an; Wang, Xiaopei

    2016-10-01

    The structural behavior and damage propagation of 3D woven composite stiffened panels with different woven patterns under axial-compression are here investigated. The panel is 2.5D interlock woven composites (2.5DIWC), while the straight-stiffeners are 3D woven orthogonal composites (3DWOC). They are coupled together with the Z-fibers from the stiffener passing straight thought the thickness of the panel. A "T-shape" model, in which the fiber bundle structure and resin matrix are drawn out to simulate the real situation of the connection area, is established to predict elastic constants and strength of the connection region. Based on Hashin failure criterion, a progressive damage model is carried out to simulate the compressive behavior of the stiffened panel. The 3D woven composite stiffened panels are manufactured using RTM process and then tested. A good agreement between experimental results and numerical predicted values for the compressive failure load is obtained. From initial damage to final collapse, the panel and stiffeners will not separate each other in the connection region. The main failure mode of 3D woven composite stiffened panels is compressive failure of fiber near the loading end corner.

  8. Investigating the Potential of Using Off-Axis 3D Woven Composites in Composite Joints' Applications

    NASA Astrophysics Data System (ADS)

    Saleh, Mohamed Nasr; Wang, Ying; Yudhanto, Arief; Joesbury, Adam; Potluri, Prasad; Lubineau, Gilles; Soutis, Constantinos

    2016-09-01

    The effect of circular notch has been evaluated for three different architectures of three-dimensional (3D) carbon fibre woven composites (orthogonal, ORT; layer-to-layer, LTL; angle interlock, AI) through open-hole quasi-static tension and double-lap bearing strength tests in the off-axis (45°) direction. Damage characterisation is monitored using Digital Image correlation (DIC) for open-hole testing and X-ray Computed Tomography (CT) for double-lap bearing strength test. The off-axis notched 3D woven composites exhibits minor reduction (less than 10 %) of the notched strength compared to the un-notched strength. DIC strain contour clearly show stress/strain localisation regions around the hole periphery and stress/strain redistribution away from the whole due to the z-binder existence, especially for ORT architecture. Up to 50 % bearing strain, no significant difference in the bearing stress/bearing strain response is observed. However when ORT architecture was loaded up to failure, it demonstrates higher strain to failure (~140 %) followed by AI (~105 %) and lastly LTL (~85 %). X-ray CT scans reveal the effect of the z-binder architecture on damage evolution and delamination resistance. The study suggests that off-axis loaded 3D woven composites, especially ORT architecture, has a great potential of overcoming the current challenges facing composite laminates when used in composite joints' applications.

  9. Investigating the Potential of Using Off-Axis 3D Woven Composites in Composite Joints' Applications

    NASA Astrophysics Data System (ADS)

    Saleh, Mohamed Nasr; Wang, Ying; Yudhanto, Arief; Joesbury, Adam; Potluri, Prasad; Lubineau, Gilles; Soutis, Constantinos

    2017-04-01

    The effect of circular notch has been evaluated for three different architectures of three-dimensional (3D) carbon fibre woven composites (orthogonal, ORT; layer-to-layer, LTL; angle interlock, AI) through open-hole quasi-static tension and double-lap bearing strength tests in the off-axis (45°) direction. Damage characterisation is monitored using Digital Image correlation (DIC) for open-hole testing and X-ray Computed Tomography (CT) for double-lap bearing strength test. The off-axis notched 3D woven composites exhibits minor reduction (less than 10 %) of the notched strength compared to the un-notched strength. DIC strain contour clearly show stress/strain localisation regions around the hole periphery and stress/strain redistribution away from the whole due to the z-binder existence, especially for ORT architecture. Up to 50 % bearing strain, no significant difference in the bearing stress/bearing strain response is observed. However when ORT architecture was loaded up to failure, it demonstrates higher strain to failure ( 140 %) followed by AI ( 105 %) and lastly LTL ( 85 %). X-ray CT scans reveal the effect of the z-binder architecture on damage evolution and delamination resistance. The study suggests that off-axis loaded 3D woven composites, especially ORT architecture, has a great potential of overcoming the current challenges facing composite laminates when used in composite joints' applications.

  10. Polymer optical fibers integrated directly into 3D orthogonal woven composites for sensing

    NASA Astrophysics Data System (ADS)

    Hamouda, Tamer; Seyam, Abdel-Fattah M.; Peters, Kara

    2015-02-01

    This study demonstrates that standard polymer optical fibers (POF) can be directly integrated into composites from 3D orthogonal woven preforms during the weaving process and then serve as in-situ sensors to detect damage due to bending or impact loads. Different composite samples with embedded POF were fabricated of 3D orthogonal woven composites with different parameters namely number of y-/x-layers and x-yarn density. The signal of POF was not affected significantly by the preform structure. During application of resin using VARTM technique, significant drop in backscattering level was observed due to pressure caused by vacuum on the embedded POF. Measurements of POF signal while in the final composites after resin cure indicated that the backscattering level almost returned to the original level of un-embedded POF. The POF responded to application of bending and impact loads to the composite with a reduction in the backscattering level. The backscattering level almost returned back to its original level after removing the bending load until damage was present in the composite. Similar behavior occurred due to impact events. As the POF itself is used as the sensor and can be integrated throughout the composite, large sections of future 3D woven composite structures could be monitored without the need for specialized sensors or complex instrumentation.

  11. Tensile Properties and Failure Mechanism of a New 3D Nonorthogonal Woven Composite Material

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Sun, Jin; Cai, Deng'an; Zhou, Guangming

    2016-12-01

    Tensile properties and failure mechanism of a newly developed three-dimensional (3D) woven composite material named 3D nonorthogonal woven composite are investigated in this paper. The microstructure of the composite is studied and the tensile properties are obtained by quasi-static tensile tests. The failure mechanism of specimen is discussed based on observation of the fracture surfaces via electron microscope. It is found that the specimens always split along the oblique yarns and produce typical v-shaped fracture surfaces. The representative volume cell (RVC) is established based on the microstructure. A finite element analysis is conducted with periodical boundary conditions. The finite element simulation results agree well with the experimental data. By analyzing deformation and stress distribution under different loading conditions, it is demonstrated that finite element model based on RVC is valid in predicting tensile properties of 3D nonorthogonal woven composites. Stress distribution shows that the oblique yarns and warp yarns oriented along the x direction carry primary load under x tension and that warp yarns bear primary load under y tension.

  12. 3D-WOVEN FIBER-REINFORCED COMPOSITE FOR CAD/CAM DENTAL APPLICATION

    PubMed Central

    Petersen, Richard; Liu, Perng-Ru

    2016-01-01

    Three-dimensional (3D)-woven noncrimp fiber-reinforced composite (FRC) was tested for mechanical properties in the two principal directions of the main XY plane and compared to different Computer-Aided-Design/Computer-Aided-Machining (CAD/CAM) Dental Materials. The Dental Materials included ceramic with Vitablock Mark II®, ProCAD®, InCeram® Spinel, InCeram® Alumina and InCeram® Zirconia in addition to a resin-based 3M Corp. Paradigm® particulate-filled composite. Alternate material controls included Coors 300 Alumina Ceramic and a tungsten carbide 22% cobalt cermet. The 3D-woven FRC was vacuum assisted resin transfer molding processed as a one-depth-thickness ~19-mm preform with a vinyl-ester resin and cut into blocks similar to the commercial CAD/CAM Dental Materials. Mechanical test samples prepared for a flexural three-point span length of 10.0 mm were sectioned for minimum-depth cuts to compare machinability and fracture resistance between groups. 3D-woven FRC improved mechanical properties with significant statistical differences over all CAD/CAM Dental Materials and Coors Alumina Ceramic for flexural strength (p<0.001), resilience (p<0.05), work of fracture (p<0.001), strain energy release (p<0.05), critical stress intensity factor (p<0.001) and strain (p<0.001). PMID:27642198

  13. 3D-WOVEN FIBER-REINFORCED COMPOSITE FOR CAD/CAM DENTAL APPLICATION.

    PubMed

    Petersen, Richard; Liu, Perng-Ru

    2016-05-01

    Three-dimensional (3D)-woven noncrimp fiber-reinforced composite (FRC) was tested for mechanical properties in the two principal directions of the main XY plane and compared to different Computer-Aided-Design/Computer-Aided-Machining (CAD/CAM) Dental Materials. The Dental Materials included ceramic with Vitablock Mark II®, ProCAD®, InCeram® Spinel, InCeram® Alumina and InCeram® Zirconia in addition to a resin-based 3M Corp. Paradigm® particulate-filled composite. Alternate material controls included Coors 300 Alumina Ceramic and a tungsten carbide 22% cobalt cermet. The 3D-woven FRC was vacuum assisted resin transfer molding processed as a one-depth-thickness ~19-mm preform with a vinyl-ester resin and cut into blocks similar to the commercial CAD/CAM Dental Materials. Mechanical test samples prepared for a flexural three-point span length of 10.0 mm were sectioned for minimum-depth cuts to compare machinability and fracture resistance between groups. 3D-woven FRC improved mechanical properties with significant statistical differences over all CAD/CAM Dental Materials and Coors Alumina Ceramic for flexural strength (p<0.001), resilience (p<0.05), work of fracture (p<0.001), strain energy release (p<0.05), critical stress intensity factor (p<0.001) and strain (p<0.001).

  14. Meso-Scale Modeling to Characterize Moisture Absorption of 3D Woven Composite

    NASA Astrophysics Data System (ADS)

    Yuan, Yuan; Zhou, Chu-wei

    2016-08-01

    For polymer-matrix composites, moisture is expected to degrade their mechanical properties due to matrix plasticization and moisture introduced micro-scale defects. In this study, the moisture absorptions of bulk epoxy, unidirectional composite (UD) and 3D woven composite (3D WC) were tested. Two-stage features have been observed for all these three materials. Moisture properties for UD and 3D WC were found not in simple direct proportion to their matrix volume fractions. The moisture approach of UD was modeled including the effect of fiber/matrix interphase which promotes the moisture uptake. Then, meso-scale FE model for 3D WC was established to characterize the inhomogeneous moisture diffusion. The moisture properties of resin-rich region and fiber bundle in 3D WC were determined from water uptake experiments of bulk epoxy and UD, respectively. Through homogenizing moisture properties of surface and interior weave structures, a simplified theoretical sandwich moisture diffusion approach was established. The moisture weight gains of 3D WC predicted by both meso-scale FE model and simplified sandwich approach were well agreed with the experimental data.

  15. Shear Behavior of 3D Woven Hollow Integrated Sandwich Composites: Experimental, Theoretical and Numerical Study

    NASA Astrophysics Data System (ADS)

    Zhou, Guangming; Liu, Chang; Cai, Deng'an; Li, Wenlong; Wang, Xiaopei

    2016-11-01

    An experimental, theoretical and numerical investigation on the shear behavior of 3D woven hollow integrated sandwich composites was presented in this paper. The microstructure of the composites was studied, then the shear modulus and load-deflection curves were obtained by double lap shear tests on the specimens in two principal directions of the sandwich panels, called warp and weft. The experimental results showed that the shear modulus of the warp was higher than that of the weft and the failure occurred in the roots of piles. A finite element model was established to predict the shear behavior of the composites. The simulated results agreed well with the experimental data. Simultaneously, a theoretical method was developed to predict the shear modulus. By comparing with the experimental data, the accuracy of the theoretical method was verified. The influence of structural parameters on shear modulus was also discussed. The higher yarn number, yarn density and dip angle of the piles could all improve the shear modulus of 3D woven hollow integrated sandwich composites at different levels, while the increasing height would decrease the shear modulus.

  16. Effect of tow alignment on the mechanical performance of 3D woven textile composites

    NASA Technical Reports Server (NTRS)

    Norman, Timothy L.; Allison, Patti; Baldwin, Jack W.; Gracias, Brian K.; Seesdorf, Dave

    1993-01-01

    Three-dimensional (3D) woven preforms are currently being considered for use as primary structural components. Lack of technology to properly manufacture, characterize and predict mechanical properties, and predict damage mechanisms leading to failure are problems facing designers of textile composite materials. Two material systems with identical specifications but different manufacturing approaches are investigated. One manufacturing approach resulted in an irregular (nonuniform) preform geometry. The other approach yielded the expected preform geometry (uniform). The objectives are to compare the mechanical properties of the uniform and nonuniform angle interlock 3D weave constructions. The effect of adding layers of laminated tape to the outer surfaces of the textile preform is also examined. Damage mechanisms are investigated and test methods are evaluated.

  17. Three-axis distributed fiber optic strain measurement in 3D woven composite structures

    NASA Astrophysics Data System (ADS)

    Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David

    2013-03-01

    Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading.

  18. Three-Axis Distributed Fiber Optic Strain Measurement in 3D Woven Composite Structures

    NASA Technical Reports Server (NTRS)

    Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David

    2013-01-01

    Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading. Keywords: fiber optic, distributed strain sensing, Rayleigh scatter, optical frequency domain reflectometry

  19. Modeling and characterization of through-the-thickness properties of 3D woven composites

    NASA Technical Reports Server (NTRS)

    Hartranft, Dru; Pravizi-Majidi, Azar; Chou, Tsu-Wei

    1995-01-01

    The through-the-thickness properties of three-dimensionally (3D) woven carbon/epoxy composites have been studied. The investigation aimed at the evaluation and development of test methodologies for the property characterization in the thickness direction, and the establishment of fiber architectures were studied: layer-to-layer Angle Interlock, through-the-thickness Orthogonal woven preform with surface pile was also designed and manufactured for the fabrication of tensile test coupons with integrated grips. All the preforms were infiltrated by the resin transfer molding technique. The microstructures of the composites were characterized along the warp and fill (weft) directions to determine the degree of yarn undulations, yarn cross-sectional shapes, and microstructural dimensions. These parameters were correlated to the fiber architecture. Specimens were designed and tested for the direct measurement of the through-the-thickness tensile, compressive and shear properties of the composites. Design optimization was conducted through the analysis of the stress fields within the specimen coupled with experimental verification. The experimentally-derived elastic properties in the thickness direction compared well with analytical predictions obtained from a volume averaging model.

  20. Tensile Properties and Failure Mechanism of 3D Woven Hollow Integrated Sandwich Composites

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Cai, Deng'an; Zhou, Guangming; Lu, Fangzhou

    2017-01-01

    Tensile properties and failure mechanism of 3D woven hollow integrated sandwich composites are investigated experimentally, theoretically and numerically in this paper. Firstly, the tensile properties are obtained by quasi-static tensile tests on the specimens in two principal directions of the sandwich panels, called warp and weft. The experimental results shows that the tensile performances of the warp are better than that of the weft. By observing the broken specimens, it is found that the touch parts between yarns are the main failure regions under tension. Then, a theoretical method is developed to predict the tensile properties. By comparing with the experimental data, the accuracy of the theoretical method is verified. Simultaneously, a finite element model is established to predict the tensile behavior of the composites. The numerical results agree well with the experimental data. Moreover, the simulated progressive damages show that the contact regions in the warp and weft tension are both the initial failure areas.

  1. An Evaluation of 3D Woven Orthogonal Composites' Potential in the Automotive Supply Chain

    NASA Astrophysics Data System (ADS)

    Taylor, Dalia

    The automotive supply chain and its management can be a very complex process and comprises a long dynamic and complex network that consists of four primary segments: original equipment manufacturers (OEMs), first tier suppliers, sub tiers suppliers, and infrastructure suppliers. During the analysis of the current automotive industry it was identified that textile industry importance is considerable increasing as a part of the global automotive supply chain, because textile products are used for interior, exterior and even suspension parts and components. Automotive industry has an increasing demand for higher quality exterior panels with better functional properties and reduced weight. One of the main potentials for this demand is based on the three-dimensional woven composites technology innovations which can replace an existing technology. The new role of the textile industry could make important changes in the automotive supply chain industry, such as: changes in the size of the supply chain, the time to the market and the position of textile industry in the automotive supply chain structure. 3D composite materials from high performance fibers, such as glass and carbon, have been used for automotive applications in a limited way due to the low production rate and the lack of research and development. This research will contribute to the understanding of textile composites in transportation and the textile parameters that affect the performance characteristics of these materials. The research examines the performance characteristics of lighter and stronger 3D woven fabric composites made from fiberglass with the aim to improve fuel efficiency by reducing the total vehicle weight while maintaining safety standards. The performance characteristics of the 3D woven fabric composite can be designed by changing different construction parameters, such as picks density, pick roving linear density, arrangements of warp and z-yarns, and the number of warp and picks layers

  2. Fatigue of a 3D Orthogonal Non-crimp Woven Polymer Matrix Composite at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Wilkinson, M. P.; Ruggles-Wrenn, M. B.

    2017-02-01

    Tension-tension fatigue behavior of two polymer matrix composites (PMCs) was studied at elevated temperature. The two PMCs consist of the NRPE polyimide matrix reinforced with carbon fibers, but have different fiber architectures: the 3D PMC is a singly-ply non-crimp 3D orthogonal weave composite and the 2D PMC, a laminated composite reinforced with 15 plies of an eight harness satin weave (8HSW) fabric. In order to assess the performance and suitability of the two composites for use in aerospace components designed to contain high-temperature environments, mechanical tests were performed under temperature conditions simulating the actual operating conditions. In all elevated temperature tests performed in this work, one side of the test specimen was at 329 °C while the other side was open to ambient laboratory air. The tensile stress-strain behavior of the two composites was investigated and the tensile properties measured for both on-axis (0/90) and off-axis (±45) fiber orientations. Elevated temperature had little effect on the on-axis tensile properties of the two composites. The off-axis tensile strength of both PMCs decreased slightly at elevated temperature. Tension-tension fatigue tests were conducted at elevated temperature at a frequency of 1.0 Hz with a ratio of minimum stress to maximum stress of R = 0.05. Fatigue run-out was defined as 2 × 105 cycles. Both strain accumulation and modulus evolution during cycling were analyzed for each fatigue test. The laminated 2D PMC exhibited better fatigue resistance than the 3D composite. Specimens that achieved fatigue run-out were subjected to tensile tests to failure to characterize the retained tensile properties. Post-test examination under optical microscope revealed severe delamination in the laminated 2D PMC. The non-crimp 3D orthogonal weave composite offered improved delamination resistance.

  3. Performance of Composites from 3D Orthogonal Woven Preforms in terms of Architecture and Sample Location during Resin Infusion

    NASA Astrophysics Data System (ADS)

    Ince, Mehmet Erdem

    Geometric modeling of woven preforms is a useful tool to predict preform thickness, preform areal density and fiber volume fraction (FVF) of constituent yarns. Previous geometrical models of 3D orthogonal woven preforms, which are extensively reviewed in Chapter 2, were limited to plain weave interlacing pattern in jammed case. In this study, generalized geometric models in terms of weave design (represented by a numerical value termed "weave factor") were developed. The models cover both jammed and non-jammed cases, consider circular, racetrack, and rectangular yarn cross-sectional shapes. The models predict thickness, constituent yarn weights, and FVFs of 3D orthogonal woven preforms. The models illustrated fabric architecture potential of 3D orthogonal woven preforms. Numerical results for hypothetical structures showed how to control through the thickness components of the z-yarn and total FVF, that have direct effect on the in-plane and out-of-plane properties, with interlacing pattern (weave factor) and z-yarn linear density. The models were demonstrated as an essential design tool that may be used to develop composites with predicted level of structural parameters and performance. Broad range of 3D orthogonal woven preforms from glass fibers with different architectures were woven and consolidated by vacuum infusion process (VIP) with different z-yarn interlacing pattern, number of y-yarn layers, and x-yarn spacing to verify the model for filament yarns. Dry preform thickness and weight of in-plane yarns predicted by the geometric model for filament yarns correlated well with experimental results. Z-yarn weight of dry preform was 24.3% overestimated by the model due to shortening of z-yarn at cross overs in real preforms due to the flattening of x-yarns caused by the tension of z-yarns. Total FVF of actual dry preform was 0.4% greater than model prediction. However, total FVF of composite was 5.4% overestimated by the model, which is within the experimental

  4. Fabrication and characterization of nanoclay modified PMR type polyimide composites reinforced with 3D woven basalt fabric

    NASA Astrophysics Data System (ADS)

    Xie, Jianfei; Qiu, Yiping

    2009-07-01

    Nanoclay modified PMR type polyimide composites were prepared from 3D orthogonal woven basalt fiber performs and nanoclay modified polyimide matrix resin, which derived from methylene dianiline (MDA), dimethyl ester of 3,3',4,4'- oxydiphthalic acid (ODPE), monomethyl ester of cis-5-norbornene-endo-2,3-dicarboxylic acid (NE) and nanoclay. The Na+-montmorillonite was organically treated using a 1:1 molar ratio mixture of dodecylamine (C12) and MDA. The rheological properties of neat B-stage PMR polyimide and 2% clay modified B-stage PMR polyimide were investigated. Based on the results obtained from the rheological tests, a two step compression molding process can be established for the composites. In the first step, the 3D fabric preforms were impregnated with polyimide resin in a vacuum oven and heated up for degassing the volatiles and by-products. In the second step, composites were compressed. The internal structure of the composites was observed by a microscope. Incorporation of 2% clay showed an improvement in the Tg and stiffness of the PMR polyimide. The resulting composites exhibited high thermal stability and good mechanical properties.

  5. Bending response of 3-D woven and braided preform composite materials

    SciTech Connect

    Pochiraju, K.; Parvizi-Majidi, A.; Chou, T.W.; Shah, B.

    1994-12-31

    Three dimensional textile carbon-epoxy composites exhibit general anisotropy. Further, these materials may possess different modulus in uniaxial tension than that in compression. In an earlier material characterization effort, the tension, compression, and shear properties of these composites were determined. In this paper, theoretical modeling of flexure of the textile composites and experimental correlation are presented. Four point bending tests were conducted according to STM D709 standards to determine the load to mid-span deflection relationships for typical textile composites. The results of experimental analysis are compared with classical beam theory, theory of elasticity solutions considering material orthotropy and shear deflection, and finite element analysis considering material orthotropy and finite deformation/rotations. The derivation of a harmonic function, required for the theory of elasticity solution, is described in the paper. Homogeneous orthotropic elastic properties are assumed for the 3-D textile composites, which is a reasonable approximation for specimens considerably larger than the repeated geometric unit of the fiber preform. The so called ``flex modulus`` is determined from the experimental data.

  6. A Novel Method for Dynamic Short-Beam Shear Testing of 3D Woven Composites

    DTIC Science & Technology

    2011-08-11

    Yip MC, Lin JL (1998) Effects of low-energy impact on the fatigue behavior of carbon /epoxy composites. Composites Science and Technology 58(1):1–8 5...Compos- ite Materials 42(20):2111–2122 12. Davis DC, Whelan BD (2012) An experimental study of interlam- inar shear fracture toughness of a nanotube ...delamination toughness of stitched graphite/epoxy textile composites. Composites Science and Technology 57(7):729–737 15. Chen L, Ifju PG, Sankar BV (2001) A

  7. A Numerical Study on the Thermal Conductivity of 3D Woven C/C Composites at High Temperature

    NASA Astrophysics Data System (ADS)

    Shigang, Ai; Rujie, He; Yongmao, Pei

    2015-12-01

    Experimental data for Carbon/Carbon (C/C) constituent materials are combined with a three dimensional steady state heat transfer finite element analysis to demonstrate the average in-plane and out-of-plane thermal conductivities (TCs) of C/C composites. The finite element analysis is carried out at two distinct length scales: (a) a micro scale comparable with the diameter of carbon fibres and (b) a meso scale comparable with the carbon fibre yarns. Micro-scale model calculate the TCs at the fibre yarn scale in the three orthogonal directions ( x, y and z). The output results from the micro-scale model are then incorporated in the meso-scale model to obtain the global TCs of the 3D C/C composite. The simulation results are quite consistent with the theoretical and experimental counterparts reported in references. Based on the numerical approach, TCs of the 3D C/C composite are calculated from 300 to 2500 K. Particular attention is given in elucidating the variations of the TCs with temperature. The multi-scale models provide an efficient approach to predict the TCs of 3D textile materials, which is helpful for the thermodynamic property analysis and structure design of the C/C composites.

  8. Micromechanical Modeling of Woven Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Pindera, Marek-Jerzy

    1997-01-01

    This report presents the results of an extensive micromechanical modeling effort for woven metal matrix composites. The model is employed to predict the mechanical response of 8-harness (8H) satin weave carbon/copper (C/Cu) composites. Experimental mechanical results for this novel high thermal conductivity material were recently reported by Bednarcyk et al. along with preliminary model results. The micromechanics model developed herein is based on an embedded approach. A micromechanics model for the local (micro-scale) behavior of the woven composite, the original method of cells (Aboudi), is embedded in a global (macro-scale) micromechanics model (the three-dimensional generalized method of cells (GMC-3D) (Aboudi). This approach allows representation of true repeating unit cells for woven metal matrix composites via GMC-3D, and representation of local effects, such as matrix plasticity, yarn porosity, and imperfect fiber-matrix bonding. In addition, the equations of GMC-3D were reformulated to significantly reduce the number of unknown quantities that characterize the deformation fields at the microlevel in order to make possible the analysis of actual microstructures of woven composites. The resulting micromechanical model (WCGMC) provides an intermediate level of geometric representation, versatility, and computational efficiency with respect to previous analytical and numerical models for woven composites, but surpasses all previous modeling work by allowing the mechanical response of a woven metal matrix composite, with an elastoplastic matrix, to be examined for the first time. WCGMC is employed to examine the effects of composite microstructure, porosity, residual stresses, and imperfect fiber-matrix bonding on the predicted mechanical response of 8H satin C/Cu. The previously reported experimental results are summarized, and the model predictions are compared to monotonic and cyclic tensile and shear test data. By considering appropriate levels of porosity

  9. Development of 3D Woven Ablative Thermal Protection Systems (TPS) for NASA Spacecraft

    NASA Technical Reports Server (NTRS)

    Feldman, Jay D.; Ellerby, Don; Stackpoole, Mairead; Peterson, Keith; Venkatapathy, Ethiraj

    2015-01-01

    The development of a new class of thermal protection system (TPS) materials known as 3D Woven TPS led by the Entry Systems and Technology Division of NASA Ames Research Center (ARC) will be discussed. This effort utilizes 3D weaving and resin infusion technologies to produce heat shield materials that are engineered and optimized for specific missions and requirements. A wide range of architectures and compositions have been produced and preliminarily tested to prove the viability and tailorability of the 3D weaving approach to TPS.

  10. Failure in Three-Dimensional Woven Composites Subjected to Quasi-Static and Dynamic Indentation

    DTIC Science & Technology

    2013-09-12

    composites, High strain rate testing, Impact behavior, Interlaminar shear strength, Short beam shear strength, Textile composites Bhavani V. Sankar...propagation in plain woven laminates and 3D orthogonal woven composites during short beam shear tests were analyzed using FEA. Two kinds of 3D woven...delamination damage caused by such impacts the characterization of delamination damage in laminated composites becomes critical to creating safe designs. 3D

  11. Comparison of Failure Modes in 2-D and 3-D Woven Carbon Phenolic Systems

    NASA Technical Reports Server (NTRS)

    Rossman, Grant A.; Stackpoole, Mairead; Feldman, Jay; Venkatapathy, Ethiraj; Braun, Robert D.

    2013-01-01

    NASA Ames Research Center is developing Woven Thermal Protection System (WTPS) materials as a new class of heatshields for entry vehicles (Stackpoole). Currently, there are few options for ablative entry heatshield materials, none of which is ideally suited to the planetary probe missions currently of interest to NASA. While carbon phenolic was successfully used for the missions Pioneer Venus and Galileo (to Jupiter), the heritage constituents are no longer available. An alternate carbon phenolic would need to be qualified for probe missions, which is most efficient at heat fluxes greater than those currently of interest. Additional TPS materials such as Avcoat and PICA are not sufficiently robust for the heat fluxes required. As a result, there is a large TPS gap between the materials efficient at very high conditions (carbon phenolic) and those that are effective at low-moderate conditions (all others). Development of 3D Woven TPS is intended to fill this gap, targeting mid-density weaves that could with withstand mid-range heat fluxes between 1100 W/sq cm and 8000 W/sq cm (Venkatapathy (2012). Preliminary experimental studies have been performed to show the feasibility of WTPS as a future mid-range TPS material. One study performed in the mARC Jet Facility at NASA Ames Research Center characterized the performance of a 3D Woven TPS sample and compared it to 2D carbon phenolic samples at ply angles of 0deg, 23.5deg, and 90deg. Each sample contained similar compositions of phenolic and carbon fiber volume fractions for experimental consistency. The goal of this study was to compare the performance of the TPS materials by evaluating resulting recession and failure modes. After exposing both samples to similar heat flux and pressure conditions, the 2D carbon phenolic laminate was shown to experience significant delamination between layers and further pocketing underneath separated layers. The 3D Woven TPS sample did not experience the delamination or pocketing

  12. 3D Woven-Like Carbon Micropattern Decorated with Silicon Nanoparticles for Use in Lithium-Ion Batteries.

    PubMed

    Kang, Da-Young; Kim, Cheolho; Gueon, Donghee; Park, Gyulim; Kim, Jung Sub; Lee, Joong Kee; Moon, Jun Hyuk

    2015-10-26

    Carbon/silicon composite materials are a promising anode substrate for use in lithium-ion batteries. In this study, we suggest a new architecture for a composite electrode made of a woven-like carbon material decorated with silicon nanoparticles. The 3D woven-like carbon (WLC) structure was fabricated using direct carbonization of multi-beam interference lithography polymer patterns. Subsequent solution coating was applied to decorate the WLC with silicon nanoparticles (SiNPs). The SiNP/WLC electrode exhibited a specific capacity of 930 mAh g(-1) , which is three times higher than the specific capacity of the bare electrode. Specifically, the SiNP/WLC electrode exhibited an outstanding retention capacity of 81 % after 50 cycles and a Coulombic efficiency of more than 98 %. This rate capability performance was attributed to the WLC structure and the uniform decoration of the SiNPs.

  13. Pack Aluminization Synthesis of Superalloy 3D Woven and 3D Braided Structures

    NASA Astrophysics Data System (ADS)

    Erdeniz, Dinc; Levinson, Amanda J.; Sharp, Keith W.; Rowenhorst, David J.; Fonda, Richard W.; Dunand, David C.

    2015-01-01

    Micro-architectured, precipitation-strengthened structures were created in a new process combining weaving, gas-phase alloying, diffusion, and precipitation. First, high-ductility Ni-20 wt pct Cr wires with 202 μm diameter were braided, or non-crimp orthogonal woven, into three-dimensional structures. Second, these structures were vapor-phase alloyed with Al at 1273 K (1000 °C) by pack cementation, creating uniform NiAl coatings on the wires when using a retort. Also, solid-state bonding was achieved at wire intersections, where two wires were sufficiently close to each other, as determined via optical and X-ray tomographic microscopy. Third, the NiAl-coated wires were fully homogenized and aged to form γ' precipitates distributed in a γ matrix phase, the same microstructure providing strength in nickel-based superalloys. The resulting structures—consisting of wires (i) woven in a controlled three-dimensional architecture, (ii) bonded at contact points and (iii) strengthened by γ' precipitates—are expected to show high strength at ambient and elevated temperatures, low density, and high permeability which is useful for active cooling.

  14. Thermo-responsive non-woven scaffolds for "smart" 3D cell culture.

    PubMed

    Rossouw, Claire L; Chetty, Avashnee; Moolman, Francis Sean; Birkholtz, Lyn-Marie; Hoppe, Heinrich; Mancama, Dalu T

    2012-08-01

    The thermo-responsive polymer poly(N-isopropylacrylamide) has received widespread attention for its in vitro application in the non-invasive, non-destructive release of adherent cells on two dimensional surfaces. In this study, 3D non-woven scaffolds fabricated from poly(propylene) (PP), poly(ethylene terephthalate) (PET), and nylon that had been grafted with PNIPAAm were tested for their ability to support the proliferation and subsequent thermal release of HC04 and HepG2 hepatocytes. Hepatocyte viability and proliferation were estimated using the Alamar Blue assay and Hoechst 33258 total DNA quantification. The assays revealed that the pure and grafted non-woven scaffolds maintained the hepatocytes within the matrix and promoted 3D proliferation comparable to that of the commercially available Algimatrix™ alginate scaffold. Albumin production and selected cytochrome P450 genes expression was found to be superior in cells growing on pure and grafted non-woven PP scaffolds as compared to cells grown as a 2D monolayer. Two scaffolds, namely, PP-g-PNIPAAm-A and PP-g-PNIPAAm-B were identified as having far superior thermal release capabilities; releasing the majority of the cells from the matrices within 2 h. This is the first report for the development of 3D non-woven, thermo-responsive scaffolds able to release cells from the matrix without the use of any enzymatic assistance or scaffold degradation.

  15. Flexural performance of woven hybrid composites

    NASA Astrophysics Data System (ADS)

    Maslinda, A. B.; Majid, M. S. Abdul; Dan-mallam, Y.; Mazawati, M.

    2016-07-01

    This paper describes the experimental investigation of the flexural performance of natural fiber reinforced polymer composites. Hybrid composites consist of interwoven kenaf/jute and kenaf/hemp fibers was prepared by infusion process using epoxy as polymer matrix. Woven kenaf, jute and hemp composites were also prepared for comparison. Both woven and hybrid composites were subjected to three point flexural test. From the result, bending resistance of hybrid kenaf/jute and kenaf/hemp composites was higher compared to their individual fiber. Hybridization with high strength fiber such as kenaf enhanced the capability of jute and hemp fibers to withstand bending load. Interlocking between yarns in woven fabric make pull out fibers nearly impossible and increase the flexural performance of the hybrid composites.

  16. Computational Simulation of Damage Propagation in Three-Dimensional Woven Composites

    NASA Technical Reports Server (NTRS)

    Huang, Dade; Minnetyan, Levon

    2005-01-01

    Three dimensional (3D) woven composites have demonstrated multi-directional properties and improved transverse strength, impact resistance, and shear characteristics. The objective of this research is to develop a new model for predicting the elastic constants, hygrothermal effects, thermomechanical response, and stress limits of 3D woven composites; and to develop a computational tool to facilitate the evaluation of 3D woven composite structures with regard to damage tolerance and durability. Fiber orientations of weave and braid patterns are defined with reference to composite structural coordinates. Orthotropic ply properties and stress limits computed via micromechanics are transformed to composite structural coordinates and integrated to obtain the 3D properties. The various stages of degradation, from damage initiation to collapse of structures, in the 3D woven structures are simulated for the first time. Three dimensional woven composite specimens with various woven patterns under different loading conditions, such as tension, compression, bending, and shear are simulated in the validation process of this research. Damage initiation, growth, accumulation, and propagation to fracture are included in these simulations.

  17. Micromechanics of fatigue in woven and stitched composites

    NASA Technical Reports Server (NTRS)

    Cox, B. N.; Carter, W. C.; Dadkhah, M. S.; Morris, W. L.

    1994-01-01

    The goals of this research program were to: (1) determine how microstructural factors, especially the architecture of reinforcing fibers, control stiffness, strength, and fatigue life in 3D woven composites; (2) identify mechanisms of failure; (3) model composite stiffness; (4) model notched and unnotched strength; and (5) model fatigue life. We have examined a total of eleven different angle and orthogonal interlock woven composites. Extensive testing has revealed that these 3D woven composites possess an extraordinary combination of strength, damage tolerance, and notch insensitivity in compression and tension and in monotonic and cyclic loading. In many important regards, 3D woven composites far outstrip conventional 2D laminates or stitched laminates. Detailed microscopic analysis of damage has led to a comprehensive picture of the essential mechanisms of failure and how they are related to the reinforcement geometry. The critical characteristics of the weave architecture that promote favorable properties have been identified. Key parameters are tow size and the distributions in space and strength of geometrical flaws. The geometrical flaws should be regarded as controllable characteristics of the weave in design and manufacture. In addressing our goals, the simplest possible models of properties were always sought, in a blend of old and new modeling concepts. Nevertheless, certain properties, especially regarding damage tolerance, ultimate failure, and the detailed effects of weave architecture, require computationally intensive stochastic modeling. We have developed a new model, the 'binary model,' to carry out such tasks in the most efficient manner and with faithful representation of crucial mechanisms. This is the final report for contract NAS1-18840. It covers all work from April 1989 up to the conclusion of the program in January 1993.

  18. 3D Printable Graphene Composite

    PubMed Central

    Wei, Xiaojun; Li, Dong; Jiang, Wei; Gu, Zheming; Wang, Xiaojuan; Zhang, Zengxing; Sun, Zhengzong

    2015-01-01

    In human being’s history, both the Iron Age and Silicon Age thrived after a matured massive processing technology was developed. Graphene is the most recent superior material which could potentially initialize another new material Age. However, while being exploited to its full extent, conventional processing methods fail to provide a link to today’s personalization tide. New technology should be ushered in. Three-dimensional (3D) printing fills the missing linkage between graphene materials and the digital mainstream. Their alliance could generate additional stream to push the graphene revolution into a new phase. Here we demonstrate for the first time, a graphene composite, with a graphene loading up to 5.6 wt%, can be 3D printable into computer-designed models. The composite’s linear thermal coefficient is below 75 ppm·°C−1 from room temperature to its glass transition temperature (Tg), which is crucial to build minute thermal stress during the printing process. PMID:26153673

  19. Elastic properties of woven fabric reinforced composites

    NASA Technical Reports Server (NTRS)

    Ramnath, V.

    1985-01-01

    An analytical model for the realistic representation of a woven fabric reinforced composite is presented in this paper. The approach uses a variable cross-section geometric model in order to achieve geometric compatibility at the yarn cross-over regions. Admissible displacement and stress fields are used to determine bounds on the fabric elastic properties. The approach adopted enables the determination of the complete three-dimensional woven fabric composite properties. The in-plane fabric properties obtained through this approach have been compared with results obtained from other approaches existing in the literature. Also, comparisons made with available experimental data indicate good agreement.

  20. In vitro generation of mechanically functional cartilage grafts based on adult human stem cells and 3D-woven poly(epsilon-caprolactone) scaffolds.

    PubMed

    Valonen, Piia K; Moutos, Franklin T; Kusanagi, Akihiko; Moretti, Matteo G; Diekman, Brian O; Welter, Jean F; Caplan, Arnold I; Guilak, Farshid; Freed, Lisa E

    2010-03-01

    Three-dimensionally woven poly(epsilon-caprolactone) (PCL) scaffolds were combined with adult human mesenchymal stem cells (hMSC) to engineer mechanically functional cartilage constructs in vitro. The specific objectives were to: (i) produce PCL scaffolds with cartilage-like mechanical properties, (ii) demonstrate that hMSCs formed cartilage after 21 days of culture on PCL scaffolds, and (iii) study effects of scaffold structure (loosely vs. tightly woven), culture vessel (static dish vs. oscillating bioreactor), and medium composition (chondrogenic additives with or without serum). Aggregate moduli of 21-day constructs approached normal articular cartilage for tightly woven PCL cultured in bioreactors, were lower for tightly woven PCL cultured statically, and lowest for loosely woven PCL cultured statically (p<0.05). Construct DNA, total collagen, and glycosaminoglycans (GAG) increased in a manner dependent on time, culture vessel, and medium composition. Chondrogenesis was verified histologically by rounded cells within a hyaline-like matrix that immunostained for collagen type II but not type I. Bioreactors yielded constructs with higher collagen content (p<0.05) and more homogenous matrix than static controls. Chondrogenic additives yielded constructs with higher GAG (p<0.05) and earlier expression of collagen II mRNA if serum was not present in medium. These results show feasibility of functional cartilage tissue engineering from hMSC and 3D-woven PCL scaffolds.

  1. In vitro generation of mechanically functional cartilage grafts based on adult human stem cells and 3D-woven poly(ε-caprolactone) scaffolds

    PubMed Central

    Valonen, P.K.; Moutos, F.T.; Kusanagi, A.; Moretti, M.; Diekman, B.O.; Welter, J.F.; Caplan, A.I.; Guilak, F.

    2009-01-01

    Three-dimensionally woven poly(ε-caprolactone)(PCL) scaffolds were combined with adult human mesenchymal stem cells (hMSC) to engineer mechanically functional cartilage constructs in vitro. The specific objectives were to: (i) produce PCL scaffolds with cartilage-like mechanical properties, (ii) demonstrate that hMSCs formed cartilage after 21-days of culture on PCL scaffolds, and (iii) study effects of scaffold structure (loosely vs. tightly woven), culture vessel (static dish vs. oscillating bioreactor), and medium composition (chondrogenic additives with or without serum). Aggregate moduli of 21-day constructs approached normal articular cartilage for tightly woven PCL cultured in bioreactors, were lower for tightly woven PCL cultured statically, and lowest for loosely woven PCL cultured statically (p<0.05). Construct DNA, total collagen, and glyocosaminoglycans (GAG) increased in a manner dependent on time, culture vessel, and medium composition. Chondrogenesis was verified histologically by rounded cells within a hyaline-like matrix that immunostained for collagen type II but not type I. Bioreactors yielded constructs with higher collagen content (p<0.05) and more homogenous matrix than static controls. Chondrogenic additives yielded constructs with higher GAG (p<0.05) and earlier expression of collagen II mRNA if serum was not present in medium. These results show feasibility of functional cartilage tissue engineering from hMSC and 3D woven PCL scaffolds. PMID:20034665

  2. Nondestructive characterization of woven fabric ceramic composites

    SciTech Connect

    Hsu, D.K.; Saini, V.; Liaw, P.K.; Yu, N.; Miriyala, N.; McHargue, C.J.; Snead, L.L.; Lowden, R.A.

    1995-10-01

    Woven fabric ceramic composites fabricated by the chemical vapor infiltration method are susceptible to high void content and inhomogeneity. The condition of such materials may be characterized nondestructively with ultrasonic methods. In this work, longitudinal and shear waves were used in the quantitative determination of elastic constants of Nicalon{trademark}/SiC composites as a function of volume percent of porosity. Elastic stiffness constants were obtained for both the in-plane and out-of-plane directions with respect to fiber fabric. The effect of porosity on the modulus of woven fabric composites was also modeled and compared to the measured results. Scan images based on the amplitude and time-of-flight of radio frequency (RF) ultrasonic pulses were used for evaluating the material homogeneity for the purpose of optimizing the manufacturing process and for correlation with the mechanical testing results.

  3. Dry spun 3D woven carbon nanotube anode electrode for Li-lon batteries.

    PubMed

    Ryu, Seongwoo; Kim, Yunkyoung; Lee, Haeshin; Hong, Soon Hyung

    2014-12-01

    Although carbon nanotubes (CNTs) have extraordinary mechanical, thermal, and electrical properties, application of CNTs remains limited due to their unique nano-sized tubular forms. CNT electrodes have relatively high sheet resistance, which does not meet the industrial requirements of various electrode materials. Thus, there are still challenges for improving the performance of CNTs in real applications, particularly in terms of satisfying industrial requirements. In this study, to utilize CNTs in bulk scale electrode applications, we developed a dry spinning technique. The dry spinning technique is a solid state fiber spinning technique that provides an adjustable aligned structure. The dry spinning approach also offers a facile and inexpensive fabrication process, factors which are favorable for industrial scalability for fabricating electrodes. We demonstrate a multilayer stacking process for enhancing the performance for Li-ion batteries. Multi-layer CNT textiles have low sheet resistance and a 3D woven structure provides high surface area. The fabricated 3D woven structured electrode delivers a higher reversible capacity of more than 400 mA hr/g with high cycle stabilities.

  4. Analysis of woven and braided fabric reinforced composites

    NASA Technical Reports Server (NTRS)

    Naik, Rajiv A.

    1994-01-01

    A general purpose micromechanics analysis that discretely models the yarn architecture within the textile repeating unit cell, was developed to predict overall, three dimensional, thermal and mechanical properties. This analytical technique was implemented in a user-friendly, personal computer-based, windows compatible code called Textile Composite Analysis for Design (TEXCAD). TEXCAD was used to analyze plain, 5-harness satin, and 8-harness satin weave composites along with 2-D braided and 2x2, 2-D triaxial braided composites. The calculated overall stiffnesses correlated well with available 3-D finite element results and test data for both the woven and the braided composites. Parametric studies were performed to investigate the effects of yarn size on the yarn crimp and the overall thermal and mechanical constants for plain weave composites. The effects of braid angle were investigated for the 2-D braided composites. Finally, the effects of fiber volume fraction on the yarn undulations and the thermal and mechanical properties of 2x2, 2-D triaxial braided composites were also investigated.

  5. Rubber Impact on 3D Textile Composites

    NASA Astrophysics Data System (ADS)

    Heimbs, Sebastian; Van Den Broucke, Björn; Duplessis Kergomard, Yann; Dau, Frederic; Malherbe, Benoit

    2012-06-01

    A low velocity impact study of aircraft tire rubber on 3D textile-reinforced composite plates was performed experimentally and numerically. In contrast to regular unidirectional composite laminates, no delaminations occur in such a 3D textile composite. Yarn decohesions, matrix cracks and yarn ruptures have been identified as the major damage mechanisms under impact load. An increase in the number of 3D warp yarns is proposed to improve the impact damage resistance. The characteristic of a rubber impact is the high amount of elastic energy stored in the impactor during impact, which was more than 90% of the initial kinetic energy. This large geometrical deformation of the rubber during impact leads to a less localised loading of the target structure and poses great challenges for the numerical modelling. A hyperelastic Mooney-Rivlin constitutive law was used in Abaqus/Explicit based on a step-by-step validation with static rubber compression tests and low velocity impact tests on aluminium plates. Simulation models of the textile weave were developed on the meso- and macro-scale. The final correlation between impact simulation results on 3D textile-reinforced composite plates and impact test data was promising, highlighting the potential of such numerical simulation tools.

  6. 3-D textile reinforcements in composite materials

    SciTech Connect

    Miravete, A.

    1999-11-01

    Laminated composite materials have been used in structural applications since the 1960s. However, their high cost and inability to accommodate fibers in the laminate`s thickness direction greatly reduce their damage tolerance and impact resistance. The second generation of materials--3-D textile reinforced composites--offers significant cost reduction, and by incorporating reinforcement in the thickness direction, dramatically increases damage tolerance and impact resistance. However, methods for predicting mechanical properties of 3-D textile reinforced composite materials tend to be more complex. These materials also have disadvantages--particularly in regard to crimps in the yarns--that require more research. Textile preforms, micro- and macromechanical modeling, manufacturing processes, and characterization all need further development. As researchers overcome these problems, this new generation of composites will emerge as a highly competitive family of materials. This book provides a state-of-the-art account of this promising technology. In it, top experts describe the manufacturing processes, highlight the advantages, identify the main applications, analyze methods for predicting mechanical properties, and detail various reinforcement strategies, including grid structure, knitted fabric composites, and the braiding technique. Armed with the information in this book, readers will be prepared to better exploit the advantages of 3-D textile reinforced composites, overcome its disadvantages, and contribute to the further development of the technology.

  7. Characterising Mechanical Properties of Braided and Woven Textile Composite Beams

    NASA Astrophysics Data System (ADS)

    Dauda, Benjamin; Oyadiji, S. Olutunde; Potluri, Prasad

    2009-02-01

    The focus of this paper is on the manufacture of textile composite beams and on the determination of their mechanical properties. This includes investigating the effects of fibre orientation on the mechanical properties of braided and woven textile composites. Composites were manufactured from nominally identical constituents and identical consolidation processes, leaving as the only variables, variations caused by the different fibre architecture of the preform. The repeatability and, hence, reliability of this approach is demonstrated. Results obtained show that fibre architecture affects composite strength and extensibility. Composites with woven preforms are practically linear up to catastrophic failure while composites with braided preforms exhibit non-linearity prior to failure. Also the mechanical properties of the textile composite beams were determined. Results show that by tailoring the braid angle and pick density of braided and woven composite performs, the mechanical properties of the composite beams can be controlled to suit end-use requirement.

  8. Modeling the Stress Strain Behavior of Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.

    2006-01-01

    Woven SiC fiber reinforced SiC matrix composites represent one of the most mature composite systems to date. Future components fabricated out of these woven ceramic matrix composites are expected to vary in shape, curvature, architecture, and thickness. The design of future components using woven ceramic matrix composites necessitates a modeling approach that can account for these variations which are physically controlled by local constituent contents and architecture. Research over the years supported primarily by NASA Glenn Research Center has led to the development of simple mechanistic-based models that can describe the entire stress-strain curve for composite systems fabricated with chemical vapor infiltrated matrices and melt-infiltrated matrices for a wide range of constituent content and architecture. Several examples will be presented that demonstrate the approach to modeling which incorporates a thorough understanding of the stress-dependent matrix cracking properties of the composite system.

  9. Tow Architecture and Mechanical Properties of 3-D Woven Composites

    DTIC Science & Technology

    2010-06-01

    within the fabric. The second was automated voxel modelling using a Python script written as part of this research program, resulting in an approximate...assignment The automated modelling approach, named ConEn V1.0, has been instituted using PYTHON 2.5 \\ Additional sub components of the code required to...develop the program include the Python Imaging Library (PIL) and Numpy. The program works by processing a series of cross-sectional images, from

  10. Effect of Hybridization on Stiffness Properties of Woven Textile Composites

    NASA Astrophysics Data System (ADS)

    Bejan, Liliana; Taranu, Nicolae; Sîrbu, Adriana

    2013-04-01

    The present study focuses on stiffness properties of woven textile reinforced polymeric composites with respect to hybridization, and geometry of reinforcement. The analyzed composites represent combinations of different fibre materials (E-glass, Kevlar 49, carbon HM) in a predetermined fabric geometry (a plane weave embedded in thermosetting polymeric resin) serving controlled properties and required performance. The effects of hybridization on the stiffness properties of woven textile composites have been studied with respect to the fibres materials, the unbalancing degree of fabrics, and the variation of compactness and undulation of yarns. Some undesirable effects in fabric geometry can be overcome by the combined effects of hybridization and compactness.

  11. Mechanisms of compressive failure in woven composites and stitched laminates

    NASA Technical Reports Server (NTRS)

    Cox, B. N.; Dadkhah, M. S.; Inman, R. V.; Morris, W. L.; Schroeder, S.

    1992-01-01

    Stitched laminates and angle interlock woven composites have been studied in uniaxial, in-plane, monotonic compression. Failure mechanisms have been found to depend strongly on both the reinforcement architecture and the degree of constraint imposed by the loading grips. Stitched laminates show higher compressive strength, but are brittle, possessing no load bearing capacity beyond the strain for peak load. Post-mortem inspection shows a localized shear band of buckled and broken fibers, which is evidently the product of an unstably propagating kink band. Similar shear bands are found in the woven composites if the constraint of lateral displacements is weak; but, under strong constraint, damage is not localized but distributed throughout the gauge section. While the woven composites tested are weaker than the stitched laminates, they continue to bear significant loads to compressive strains of approx. 15 percent, even when most damage is confined to a shear band.

  12. Analysis of woven fabrics for reinforced composite materials

    NASA Technical Reports Server (NTRS)

    Dow, Norris F.; Ramnath, V.; Rosen, B. Walter

    1987-01-01

    The use of woven fabrics as reinforcements for composites is considered. Methods of analysis of properties are reviewed and extended, with particular attention paid to three-dimensional constructions having through-the-thickness reinforcements. Methodology developed is used parametrically to evaluate the performance potential of a wide variety of reinforcement constructions including hybrids. Comparisons are made of predicted and measured properties of representative composites having biaxial and triaxial woven, and laminated tape lay-up reinforcements. Overall results are incorporated in advanced weave designs.

  13. Modeling and characterization of 2-D and 3-D textile structural composites

    SciTech Connect

    Yang, J.M.

    1986-01-01

    This dissertation studies the analytical modeling and experimental characterization of various two-dimensional and three-dimensional textile structure composites. In the analytical approach, various theoretical models were established to predict the stiffness, strength, nonlinear deformation, and failure behavior of triaxial woven-fabric composites, 3-D braided composites, and multilayer multidirectional warp knit fabric composites in polymer and metal matrices. The structure performance maps of various textile structural composites were also established, based upon these analytical methods. In the experimental approach, extensive mechanical testing and microstructural characterization were performed to investigate the thermomechanical properties and failure behavior of 3-D braided FP/Al composites. Results of this research will serve as the basis for assessing the potential of textile composites for structural applications.

  14. Damage Accumulation in SiC/SiC Composites with 3D Architectures

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Yun, Hee-Mann; DiCarlo, James A.

    2003-01-01

    The formation and propagation of multiple matrix cracks in relatively dense ceramic matrix composites when subjected to increasing tensile stress is necessary for high strength and tough composites. However, the occurrence of matrix cracks at low stresses may limit the usefulness of some non-oxide composite systems when subjected to oxidizing environments for long times at stresses sufficient to cause matrix cracking. For SiC fiber-reinforced composites with two-dimensional woven architectures and chemically vapor infiltrated (CVI) SiC matrix and melt-infiltrated (MI) Si/SiC matrix composites, the matrix cracking behavior has been fairly well characterized for different fiber-types and woven architectures. It was found that the occurrence, degree, and growth of matrix cracks depends on the material properties of the composite constituents as well as other physical properties of the composite or architecture, e.g., matrix porosity and size of the fiber bundle. In this study, matrix cracking in SiC fiber reinforced, melt-infiltrated SiC composites with a 3D orthogonal architecture was determined for specimens tested in tension at room temperature. Acoustic emission (AE) was used to monitor the matrix cracking activity, which was later confirmed by microscopic examination of specimens that had failed. The determination of the exact location of AE demonstrated that initial cracking occurred in the matrix rich regions when a large z-direction fiber bundle was used. For specimens with large z-direction fiber tows, the earliest matrix cracking could occur at half the stress for standard 2D woven composites with similar constituents. Damage accumulation in 3D architecture composites will be compared to damage accumulation in 2D architecture composites and discussed with respect to modeling composite stress-strain behavior and use of these composites at elevated temperatures.

  15. Mechanical analysis of three dimensional woven carbon fiber-reinforced composites using fiber-based continuum model

    NASA Astrophysics Data System (ADS)

    Ahn, Hyunchul; An, Yongsan; Yu, Woong-Ryeol

    2016-10-01

    A new numerical method for analyzing the mechanical behavior of three-dimensional (3D) woven carbon fiber-reinforced composites was developed by considering changes in the fiber orientation and calculating the stress increments due to incremental deformations. The model consisted of four steps, starting update of the yarn orientation based on incremental deformation gradient. The stiffness matrix was then computed using the updated yarn orientation. Next, partial damage and propagation were incorporated into the stress calculation using modified ply discount method. The failure conditions were obtained by testing the unidirectional composites and formulated using Puck's criterion. This numerical model was finally implemented into commercial finite element software, ABAQUS, as a user material subroutine. As for experiment, 3D woven composite samples was manufactured using laboratory built-in system and characterized, the results of which were compared with simulated results, demonstrating that the current numerical model can properly predict the mechanical behavior of 3D fiber-reinforced composites.

  16. Woven graphite epoxy composite test specimens with glass buffer strips

    NASA Technical Reports Server (NTRS)

    Bonnar, G. R.; Palmer, R. J.

    1982-01-01

    Woven unidirectional graphite cloth with bands of fiberglass replacing the graphite in discrete lengthwise locations was impregnated with epoxy resin and used to fabricate a series of composite tensile and shear specimens. The finished panels, with the fiberglass buffer strips, were tested. Details of the fabrication process are reported.

  17. Modeling Woven Polymer Matrix Composites with MAC/GMC

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Arnold, Steven M. (Technical Monitor)

    2000-01-01

    NASA's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) is used to predict the elastic properties of plain weave polymer matrix composites (PMCs). The traditional one step three-dimensional homogertization procedure that has been used in conjunction with MAC/GMC for modeling woven composites in the past is inaccurate due to the lack of shear coupling inherent to the model. However, by performing a two step homogenization procedure in which the woven composite repeating unit cell is homogenized independently in the through-thickness direction prior to homogenization in the plane of the weave, MAC/GMC can now accurately model woven PMCs. This two step procedure is outlined and implemented, and predictions are compared with results from the traditional one step approach and other models and experiments from the literature. Full coupling of this two step technique with MAC/ GMC will result in a widely applicable, efficient, and accurate tool for the design and analysis of woven composite materials and structures.

  18. Failure analysis of woven and braided fabric reinforced composites

    SciTech Connect

    Naik, R.A.

    1994-09-01

    A general purpose micromechanics analysis that discretely models the yarn architecture within the textile repeating unit cell was developed to predict overall, three dimensional, thermal and mechanical properties, damage initiation and progression, and strength. This analytical technique was implemented in a user-friendly, personal computer-based, menu-driven code called Textile Composite Analysis for Design (TEXCAD). TEXCAD was used to analyze plain weave and 2x2, 2-D triaxial braided composites. The calculated tension, compression, and shear strengths correlated well with available test data for both woven and braided composites. Parametric studies were performed on both woven and braided architectures to investigate the effects of parameters such as yarn size, yarn spacing, yarn crimp, braid angle, and overall fiber volume fraction on the strength properties of the textile composite.

  19. Mechanical properties of non-woven glass fiber geopolymer composites

    NASA Astrophysics Data System (ADS)

    Rieger, D.; Kadlec, J.; Pola, M.; Kovářík, T.; Franče, P.

    2017-02-01

    This experimental research focuses on mechanical properties of non-woven glass fabric composites bound by geopolymeric matrix. This study investigates the effect of different matrix composition and amount of granular filler on the mechanical properties of final composites. Matrix was selected as a metakaolin based geopolymer hardened by different amount of potassium silicate activator. The ceramic granular filler was added into the matrix for investigation of its impact on mechanical properties and workability. Prepared pastes were incorporated into the non-woven fabrics by hand roller and final composites were stacked layer by layer to final thickness. The early age hardening of prepared pastes were monitored by small amplitude dynamic rheology approach and after 28 days of hardening the mechanical properties were examined. The electron microscopy was used for detail description of microstructural properties. The imaging methods revealed good wettability of glass fibers by geopolymeric matrix and results of mechanical properties indicate usability of these materials for constructional applications.

  20. Failure analysis of woven and braided fabric reinforced composites

    NASA Technical Reports Server (NTRS)

    Naik, Rajiv A.

    1994-01-01

    A general purpose micromechanics analysis that discretely models the yarn architecture within the textile repeating unit cell was developed to predict overall, three dimensional, thermal and mechanical properties, damage initiation and progression, and strength. This analytical technique was implemented in a user-friendly, personal computer-based, menu-driven code called Textile Composite Analysis for Design (TEXCAD). TEXCAD was used to analyze plain weave and 2x2, 2-D triaxial braided composites. The calculated tension, compression, and shear strengths correlated well with available test data for both woven and braided composites. Parametric studies were performed on both woven and braided architectures to investigate the effects of parameters such as yarn size, yarn spacing, yarn crimp, braid angle, and overall fiber volume fraction on the strength properties of the textile composite.

  1. Micromechanical modeling of laminated composites with interfaces and woven composites using the boundary element method

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Hopkins, Dale A.

    1993-01-01

    The boundary element method is utilized to analyze the effects of fiber/matrix interfaces on the micromechanical behavior of laminated composites as well as the elastic behavior of woven composites. Effective composite properties are computed for laminated SiC/RBSN and SiC/Ti-15-3 composites, as well as a woven SiC/SiC composite. The properties calculated using the computerized tool BEST-CMS match the experimental results well.

  2. 3D non-woven polyvinylidene fluoride scaffolds: fibre cross section and texturizing patterns have impact on growth of mesenchymal stromal cells.

    PubMed

    Schellenberg, Anne; Ross, Robin; Abagnale, Giulio; Joussen, Sylvia; Schuster, Philipp; Arshi, Annahit; Pallua, Norbert; Jockenhoevel, Stefan; Gries, Thomas; Wagner, Wolfgang

    2014-01-01

    Several applications in tissue engineering require transplantation of cells embedded in appropriate biomaterial scaffolds. Such structures may consist of 3D non-woven fibrous materials whereas little is known about the impact of mesh size, pore architecture and fibre morphology on cellular behavior. In this study, we have developed polyvinylidene fluoride (PVDF) non-woven scaffolds with round, trilobal, or snowflake fibre cross section and different fibre crimp patterns (10, 16, or 28 needles per inch). Human mesenchymal stromal cells (MSCs) from adipose tissue were seeded in parallel on these scaffolds and their growth was compared. Initial cell adhesion during the seeding procedure was higher on non-wovens with round fibres than on those with snowflake or trilobal cross sections. All PVDF non-woven fabrics facilitated cell growth over a time course of 15 days. Interestingly, proliferation was significantly higher on non-wovens with round or trilobal fibres as compared to those with snowflake profile. Furthermore, proliferation increased in a wider, less dense network. Scanning electron microscopy (SEM) revealed that the MSCs aligned along the fibres and formed cellular layers spanning over the pores. 3D PVDF non-woven scaffolds support growth of MSCs, however fibre morphology and mesh size are relevant: proliferation is enhanced by round fibre cross sections and in rather wide-meshed scaffolds.

  3. Fracture toughness of woven kenaf fibre reinforced composites

    NASA Astrophysics Data System (ADS)

    Ismail, AE; Masran, SH; Jamian, S.; Kamarudin, KA; Mohd Nor, MK; Muhd Nor, NH; Mohd Tobi, AL; Awang, MK

    2016-11-01

    This paper presents the role of fibre orientations on the woven-type kenaf fibre reinforced composites. According to literature survey, lack of information regarding to the fracture toughness of woven kenaf fibre reinforced composites. Fracture toughness tests were performed using ASTM D5045. Four fibre orientations were used such as 0/15/0/-15/0, 0/30/0/-30/0, 0/45/0/-45/0 and 0/90/0/-90/0 and on the other hand virgin polyester and unidirectional fibre reinforced composites were also used for comparisons. Based on the experimental works, woven-typed composites produced lower fracture toughness compared with the unidirectional fiber composite. Fracture toughness obtained from different fibre orientations composites are almost identical however 0/30/0/-30/0 and 0/90/0/-90/0 produced higher toughness relative with others. Fracture mechanisms revealed that as expected the fibres aligned along the stress direction capable to sustain better mechanical deformation and therefore producing higher fracture toughness.

  4. Finite element modelling of woven composite failure modes at the mesoscopic scale: deterministic versus stochastic approaches

    NASA Astrophysics Data System (ADS)

    Roirand, Q.; Missoum-Benziane, D.; Thionnet, A.; Laiarinandrasana, L.

    2017-01-01

    Textile composites are composed of 3D complex architecture. To assess the durability of such engineering structures, the failure mechanisms must be highlighted. Examinations of the degradation have been carried out thanks to tomography. The present work addresses a numerical damage model dedicated to the simulation of the crack initiation and propagation at the scale of the warp yarns. For the 3D woven composites under study, loadings in tension and combined tension and bending were considered. Based on an erosion procedure of broken elements, the failure mechanisms have been modelled on 3D periodic cells by finite element calculations. The breakage of one element was determined using a failure criterion at the mesoscopic scale based on the yarn stress at failure. The results were found to be in good agreement with the experimental data for the two kinds of macroscopic loadings. The deterministic approach assumed a homogeneously distributed stress at failure all over the integration points in the meshes of woven composites. A stochastic approach was applied to a simple representative elementary periodic cell. The distribution of the Weibull stress at failure was assigned to the integration points using a Monte Carlo simulation. It was shown that this stochastic approach allowed more realistic failure simulations avoiding the idealised symmetry due to the deterministic modelling. In particular, the stochastic simulations performed have shown several variations of the stress as well as strain at failure and the failure modes of the yarn.

  5. A biomimetic three-dimensional woven composite scaffold for functional tissue engineering of cartilage

    NASA Astrophysics Data System (ADS)

    Moutos, Franklin T.; Freed, Lisa E.; Guilak, Farshid

    2007-02-01

    Tissue engineering seeks to repair or regenerate tissues through combinations of implanted cells, biomaterial scaffolds and biologically active molecules. The rapid restoration of tissue biomechanical function remains an important challenge, emphasizing the need to replicate structural and mechanical properties using novel scaffold designs. Here we present a microscale 3D weaving technique to generate anisotropic 3D woven structures as the basis for novel composite scaffolds that are consolidated with a chondrocyte-hydrogel mixture into cartilage tissue constructs. Composite scaffolds show mechanical properties of the same order of magnitude as values for native articular cartilage, as measured by compressive, tensile and shear testing. Moreover, our findings showed that porous composite scaffolds could be engineered with initial properties that reproduce the anisotropy, viscoelasticity and tension-compression nonlinearity of native articular cartilage. Such scaffolds uniquely combine the potential for load-bearing immediately after implantation in vivo with biological support for cell-based tissue regeneration without requiring cultivation in vitro.

  6. Investigation of woven composites as potential cryogenic tank materials

    NASA Astrophysics Data System (ADS)

    Islam, Md. S.; Melendez-Soto, E.; Castellanos, A. G.; Prabhakar, P.

    2015-12-01

    In this paper, carbon fiber and Kevlar® fiber woven composites were investigated as potential cryogenic tank materials for storing liquid fuel in spacecraft or rocket. Towards that end, both carbon and Kevlar® fiber composites were manufactured and tested with and without cryogenic exposure. The focus was on the investigation of the influence of initial cryogenic exposure on the degradation of the composite. Tensile, flexural and inter laminar shear strength (ILSS) tests were conducted, which indicate that Kevlar® and carbon textile composites are potential candidates for use under cryogenic exposure.

  7. Fatigue strength of woven kenaf fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Ismail, A. E.; Aziz, M. A. Che Abdul

    2015-12-01

    Nowadays, green composites provide alternative to synthetic fibers for non-bearing and load-bearing applications. According to literature review, lack of information is available on the fatigue performances especially when the woven fiber is used instead of randomly oriented fibers. In order to overcome this problem, this paper investigates the fatigue strength of different fiber orientations and number of layers of woven kenaf fiber reinforced composites. Four types of fiber orientations are used namely 0°, 15°, 30° and 45°. Additionally, two numbers of layers are also considered. It is revealed that the fatigue life has no strong relationship with the fiber orientations. For identical fiber orientations, the fatigue life can be predicted considerably using the normalized stress. However as expected, the fatigue life enhancement occur when the number of layer is increased.

  8. Numerical Analysis on Double Dome Stretching Tests of Woven Composites

    NASA Astrophysics Data System (ADS)

    Lee, Wonoh; Cao, Jian; Chen, Julie; Sherwood, James

    2007-04-01

    As a result of international corporative benchmark works, material characterization of the woven fabric reinforced composites has been examined to better understand their mechanical properties and to provide the process design information for numerical analysis. Here, in order to predict thermo-forming behaviors of woven composites, the double dome stretching tests have been numerically performed for the balanced plain weave. To account for the change of fiber orientation under the large deformation, the non-orthogonal constitutive model has been utilized and nonlinear friction behavior is incorporated in the simulation. Also the equivalent material properties based on the contact status have been used for the thermo-stamping process. Blank draw-in, punch force history and fiber orientation after forming will be reported.

  9. Comparative evaluation of woven graphite-epoxy composites

    NASA Technical Reports Server (NTRS)

    Hanagud, S.; Tayebi, A.; Clinton, R. G., Jr.; Nayak, B. M.

    1979-01-01

    A comparative evaluation of some of the mechanical properties of woven graphite-epoxy composites are discussed. In particular, the types of weaves and the resin contents were chosen for comparison. The types of weaves selected are plain weave, satin weave, and tridirectional weave. The composites made of the fabrics are compared to composites made from unidirectional tapes under static and fatigue loading. During static loading, acoustic emission events were monitored. Also, examinations of fracture surfaces and polished sections both away from the fracture surface, and of virgin specimens under an electron microscope are discussed.

  10. Comparative evaluation of woven graphite-epoxy composites

    NASA Technical Reports Server (NTRS)

    Hanagud, S.; Tayebi, A.; Clinton, R. G.; Nayak, B. M.

    1979-01-01

    A comparative evaluation of some of the mechanical properties of woven graphite-epoxy composites have been discussed in this report. In particular the types of weaves and the resin contents have been chosen for comparison. The types of weaves selected are plain weaves, satin weave and tri-directional weave. The composites made of these fabrics have been compared to composites made from unidirectional tapes under static and fatigue loading. During static loading acoustic emission events have been monitored. Also, examinations of fracture surface and polished sections of specimens away from the fracture surface under an electron microscope have been discussed.

  11. Experimental Characterization and Micromechanical Modeling of Woven Carbon/Copper Composites

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Pauly, Christopher C.; Pindera, Marek-Jerzy

    1997-01-01

    The results of an extensive experimental characterization and a preliminary analytical modeling effort for the elastoplastic mechanical behavior of 8-harness satin weave carbon/copper (C/Cu) composites are presented. Previous experimental and modeling investigations of woven composites are discussed, as is the evolution of, and motivation for, the continuing research on C/Cu composites. Experimental results of monotonic and cyclic tension, compression, and Iosipescu shear tests, and combined tension-compression tests, are presented. With regard to the test results, emphasis is placed on the effect of strain gauge size and placement, the effect of alloying the copper matrix to improve fiber-matrix bonding, yield surface characterization, and failure mechanisms. The analytical methodology used in this investigation consists of an extension of the three-dimensional generalized method of cells (GMC-3D) micromechanics model, developed by Aboudi (1994), to include inhomogeneity and plasticity effects on the subcell level. The extension of the model allows prediction of the elastoplastic mechanical response of woven composites, as represented by a true repeating unit cell for the woven composite. The model is used to examine the effects of refining the representative geometry of the composite, altering the composite overall fiber volume fraction, changing the size and placement of the strain gauge with respect to the composite's reinforcement weave, and including porosity within the infiltrated fiber yarns on the in-plane elastoplastic tensile, compressive, and shear response of 8-harness satin C/Cu. The model predictions are also compared with the appropriate monotonic experimental results.

  12. Mechanical analysis of woven composites at high strain rates and its application to predicting impact behavior

    NASA Astrophysics Data System (ADS)

    Ryou, Hansun; Chung, Kwansoo; Lim, Ji-Ho

    2008-12-01

    The deformation behavior of woven composites at high strain rates was analyzed using a constitutive equation developed to describe the nonlinear, anisotropic/asymmetric and rate-dependent mechanical behavior of woven composites. The rate-dependent nonlinear behavior of woven composites was characterized at high strain rates (1 s-1 to 100 s-1) using a tensile testing method first proposed in this research. The material properties for the developed constitutive equation were determined and subsequently used in a finite element analysis of the deformation behavior of woven composites at high strain rates. Finally, the impact behavior of woven composites was predicted using the constitutive equation and the results were compared with experiments, showing that the current constitutive equation including the characterization method is adequate to describe the deformation behavior of woven composites at high strain rates up to impact level.

  13. An engineering model of woven composites based on micromechanics

    NASA Technical Reports Server (NTRS)

    Carter, W. C.; Cox, B. N.; Dadkhah, M. S.; Morris, W. L.

    1993-01-01

    Composites with three-dimensional woven architectures exhibit large strains to failure when compared to composites made up of the same materials but not with three-dimensional interlocking tows. The fracture mechanics of such three-dimensional architectures is a subject requiring substantial investigation and experimental testing. Classical fracture mechanics concepts (for instance, an isolated defect in a homogeneous body) will not be applicable to the woven fracture test specimen. The use of an isolated singularity to characterize an entire specimen is inadequate when the density of defects is considerable and the material is heterogeneous. Modelling of such a complex system requires a great deal of insight and consideration as well as prudent choices of model sizes to make numerical schemes feasible. The purpose of this manuscript is to review our recently acquired knowledge of damage accumulation in woven composites and to describe a practicable model of the macroscopic behavior in these and other complex composite architectures based on such knowledge. In this manuscript, discussion will be limited to uniaxial compressive loading; considerations of general loading (monotonic and cyclic) will appear in a subsequent manuscript. Our modelling efforts may be briefly described as follows: the composite is subdivided into microstructural elements (microelements) in which the micromechanical modelling is either understood rigorously or can be represented adequately by statistical parameters. There can be microstructural elements for many different types of composite components, such as the various types of warp and weft and matrix for three-dimensional woven composites. The physical dimensions of microelements are made as large as possible while the response within the element can still be represented by a single micromechatlical calculation. The various elements are linked together(sometimes by associating distinct corners and edges, sometimes by superposition) in a

  14. The effect of woven and non-woven fiber structure on mechanical properties polyester composite reinforced kenaf

    NASA Astrophysics Data System (ADS)

    Ratim, S.; Bonnia, N. N.; Surip, S. N.

    2012-07-01

    The effects of woven and non-woven kenaf fiber on mechanical properties of polyester composites were studied at different types of perform structures. Composite polyester reinforced kenaf fiber has been prepared via hand lay-up process by varying fiber forms into plain weave, twill and mats structure. The reinforcing efficiency of different fiber structure was compared with control of unreinforced polyester sample. It was found that the strength and stiffness of the composites are largely affected by fiber structure. A maximum value for tensile strength of composite was obtained for twill weave pattern of fiber structure while no significant different for plain weave and mat structure. The elastic modulus of composite has shown some improvement on plain and twill weave pattern. Meanwhile, lower value of modulus elasticity achieved by mats structure composite as well as control sample. The modulus of rupture and impact resistance were also analyzed. The improvement of modulus of rupture value can be seen on plain and twill weave pattern. However impact resistance doesn't show significant improvement in all types of structure except for mat fiber. The mechanical properties of kenaf fiber reinforced polyester composite found to be increased with woven and non-woven fiber structures in composite.

  15. Multi-scale modelling of strongly heterogeneous 3D composite structures using spatial Voronoi tessellation

    NASA Astrophysics Data System (ADS)

    El Said, Bassam; Ivanov, Dmitry; Long, Andrew C.; Hallett, Stephen R.

    2016-03-01

    3D composite materials are characterized by complex internal yarn architectures, leading to complex deformation and failure development mechanisms. Net-shaped preforms, which are originally periodic in nature, lose their periodicity when the fabric is draped, deformed on a tool, and consolidated to create geometrically complex composite components. As a result, the internal yarn architecture, which dominates the mechanical behaviour, becomes dependent on the structural geometry. Hence, predicting the mechanical behaviour of 3D composites requires an accurate representation of the yarn architecture within structural scale models. When applied to 3D composites, conventional finite element modelling techniques are limited to either homogenised properties at the structural scale, or the unit cell scale for a more detailed material property definition. Consequently, these models fail to capture the complex phenomena occurring across multiple length scales and their effects on a 3D composite's mechanical response. Here a multi-scale modelling approach based on a 3D spatial Voronoi tessellation is proposed. The model creates an intermediate length scale suitable for homogenisation to deal with the non-periodic nature of the final material. Information is passed between the different length scales to allow for the effect of the structural geometry to be taken into account on the smaller scales. The stiffness and surface strain predictions from the proposed model have been found to be in good agreement with experimental results. The proposed modelling framework has been used to gain important insight into the behaviour of this category of materials. It has been observed that the strain and stress distributions are strongly dependent on the internal yarn architecture and consequently on the final component geometry. Even for simple coupon tests, the internal architecture and geometric effects dominate the mechanical response. Consequently, the behaviour of 3D woven

  16. Mechanically fastened joints in woven fabric composites

    NASA Technical Reports Server (NTRS)

    Wilson, D. W.; Bozarth, M. J.; Pipes, R. B.

    1983-01-01

    Strength analysis for composite bolted joints involves the mating of a stress analysis with an appropriate mode specific failure criterion for each of the primary failure modes. The stress analysis and failure criteria are independent of each other and can be manipulated separately in order to optimize the strength analysis package formed by their coupling. Material properties tests were conducted on rubber toughened graphite-epoxy material to measure the basic strength and stiffness in the warp and fill directions and in shear. Test matrices are summarized for investigations of laminate configuration, stacking sequence, fastener diameter, edge distance, fastener half spacing, laminate thickness, and fastener torque. A three dimensional finite element analysis computer program was written and failure criteria for net tension, shearout, and bearing were determined.

  17. 3D-printing of lightweight cellular composites.

    PubMed

    Compton, Brett G; Lewis, Jennifer A

    2014-09-10

    A new epoxy-based ink is reported, which enables 3D printing of lightweight cellular composites with controlled alignment of multiscale, high-aspectratio fiber reinforcement to create hierarchical structures inspired by balsa wood. Young's modulus values up to 10 times higher than existing commercially available 3D-printed polymers are attainable, while comparable strength values are maintained.

  18. Micromechanical Continuum Damage Analysis of Plain Woven Composites

    NASA Astrophysics Data System (ADS)

    Li, L.; Aliabadi, F.; Wen, P. H.

    2015-01-01

    Application of meshfree Galerkin method to homogenization and Continuum Damage Mechanics (CDM) analysis of plain woven composites is presented. Three types of meshfree formulations are developed and include: radial basis function, moving least squares and moving Kriging. Three benchmark examples are used to demonstrated the efficiency of the meshfree formulation as well as compare the performance of the three shape functions. Non-linear stress-strain relationhip of unit cellusing the three shape functions are assessed with two benchmark examples of CDM model.

  19. The interlaminar fracture toughness of woven graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Funk, Joan G.; Deaton, Jerry W.

    1989-01-01

    The interlaminar fracture toughness of 2-D graphite/epoxy woven composites was determined as a function of stacking sequence, thickness, and weave pattern. Plain, oxford, 5-harness satin, and 8-harness satin weaves of T300/934 material were evaluated by the double cantilever beam test. The fabric material had a G (sub Ic) ranging from 2 to 8 times greater than 0 degrees unidirectional T300/934 tape material. The interlaminar fracture toughness of a particular weave style was dependent on whether the stacking sequence was symmetric or asymmetric and, in some cases, on the fabric orientation.

  20. Analytical Failure Prediction Method Developed for Woven and Braided Composites

    NASA Technical Reports Server (NTRS)

    Min, James B.

    2003-01-01

    Historically, advances in aerospace engine performance and durability have been linked to improvements in materials. Recent developments in ceramic matrix composites (CMCs) have led to increased interest in CMCs to achieve revolutionary gains in engine performance. The use of CMCs promises many advantages for advanced turbomachinery engine development and may be especially beneficial for aerospace engines. The most beneficial aspects of CMC material may be its ability to maintain its strength to over 2500 F, its internal material damping, and its relatively low density. Ceramic matrix composites reinforced with two-dimensional woven and braided fabric preforms are being considered for NASA s next-generation reusable rocket turbomachinery applications (for example, see the preceding figure). However, the architecture of a textile composite is complex, and therefore, the parameters controlling its strength properties are numerous. This necessitates the development of engineering approaches that combine analytical methods with limited testing to provide effective, validated design analyses for the textile composite structures development.

  1. Chiral braided and woven composites: design, fabrication, and electromagnetic characterization

    NASA Astrophysics Data System (ADS)

    Wheeland, Sara; Bayatpur, Farhad; Amirkhizi, Alireza V.; Nemat-Nasser, Sia

    2011-04-01

    This work presents a new chiral composite composed of copper wires braided with Kevlar and nylon to form conductive coils integrated among structural fiber. To create a fabric, these braids were woven with plain Kevlar fiber. This yielded a composite with all coils possessing the same handedness, producing a chiral material. The electromagnetic response of this fabric was first simulated using a finite element full-wave simulation. For the electromagnetic measurement, the sample was placed between two lens-horn antennas connected to a Vector Network Analyzer. The frequency response of the sample was scanned between 5.5 and 8GHz. The measured scattering parameters were then compared to those of the simulated model. The measured parameters agreed well with the simulation results, showing a considerable chirality within the measured frequency band. The new composite combines the strength and durability of traditional composites with an electromagnetic design to create a multifunctional material.

  2. The inhibition by interleukin 1 of MSC chondrogenesis and the development of biomechanical properties in biomimetic 3D woven PCL scaffolds.

    PubMed

    Ousema, Paul H; Moutos, Franklin T; Estes, Bradley T; Caplan, Arnold I; Lennon, Donald P; Guilak, Farshid; Weinberg, J Brice

    2012-12-01

    Tissue-engineered constructs designed to treat large cartilage defects or osteoarthritic lesions may be exposed to significant mechanical loading as well as an inflammatory environment upon implantation in an injured or diseased joint. We hypothesized that a three-dimensionally (3D) woven poly(ε-caprolactone) (PCL) scaffold seeded with bone marrow-derived mesenchymal stem cells (MSCs) would provide biomimetic mechanical properties in early stages of in vitro culture as the MSCs assembled a functional, cartilaginous extracellular matrix (ECM). We also hypothesized that these properties would be maintained even in the presence of the pro-inflammatory cytokine interleukin-1 (IL-1), which is found at high levels in injured or diseased joints. MSC-seeded 3D woven scaffolds cultured in chondrogenic conditions synthesized a functional ECM rich in collagen and proteoglycan content, reaching an aggregate modulus of ~0.75 MPa within 14 days of culture. However, the presence of pathophysiologically relevant levels of IL-1 limited matrix accumulation and inhibited any increase in mechanical properties over baseline values. On the other hand, the mechanical properties of constructs cultured in chondrogenic conditions for 4 weeks prior to IL-1 exposure were protected from deleterious effects of the cytokine. These findings demonstrate that IL-1 significantly inhibits the chondrogenic development and maturation of MSC-seeded constructs; however, the overall mechanical functionality of the engineered tissue can be preserved through the use of a 3D woven scaffold designed to recreate the mechanical properties of native articular cartilage.

  3. Comparative Study of 3-Dimensional Woven Joint Architectures for Composite Spacecraft Structures

    NASA Technical Reports Server (NTRS)

    Jones, Justin S.; Polis, Daniel L.; Rowles, Russell R.; Segal, Kenneth N.

    2011-01-01

    The National Aeronautics and Space Administration (NASA) Exploration Systems Mission Directorate initiated an Advanced Composite Technology (ACT) Project through the Exploration Technology Development Program in order to support the polymer composite needs for future heavy lift launch architectures. As an example, the large composite structural applications on Ares V inspired the evaluation of advanced joining technologies, specifically 3D woven composite joints, which could be applied to segmented barrel structures needed for autoclave cured barrel segments due to autoclave size constraints. Implementation of these 3D woven joint technologies may offer enhancements in damage tolerance without sacrificing weight. However, baseline mechanical performance data is needed to properly analyze the joint stresses and subsequently design/down-select a preform architecture. Six different configurations were designed and prepared for this study; each consisting of a different combination of warp/fill fiber volume ratio and preform interlocking method (Z-fiber, fully interlocked, or hybrid). Tensile testing was performed for this study with the enhancement of a dual camera Digital Image Correlation (DIC) system which provides the capability to measure full-field strains and three dimensional displacements of objects under load. As expected, the ratio of warp/fill fiber has a direct influence on strength and modulus, with higher values measured in the direction of higher fiber volume bias. When comparing the Z-fiber weave to a fully interlocked weave with comparable fiber bias, the Z-fiber weave demonstrated the best performance in two different comparisons. We report the measured tensile strengths and moduli for test coupons from the 6 different weave configurations under study.

  4. Influence of constituent properties and geometric form on behavior of woven fabric reinforced composites

    NASA Technical Reports Server (NTRS)

    Pipes, R. B.; Wilson, D. W.

    1984-01-01

    Th potential for woven fabric composite forms to increase the interlaminar strength and toughness properties of laminated composite septems is studied. Experimental and analytical studies were performed on a z-axis fabric.

  5. Living nano-micro fibrous woven fabric/hydrogel composite scaffolds for heart valve engineering.

    PubMed

    Wu, Shaohua; Duan, Bin; Qin, Xiaohong; Butcher, Jonathan T

    2017-03-15

    Regeneration and repair of injured or diseased heart valves remains a clinical challenge. Tissue engineering provides a promising treatment approach to facilitate living heart valve repair and regeneration. Three-dimensional (3D) biomimetic scaffolds that possess heterogeneous and anisotropic features that approximate those of native heart valve tissue are beneficial to the successful in vitro development of tissue engineered heart valves (TEHV). Here we report the development and characterization of a novel composite scaffold consisting of nano- and micro-scale fibrous woven fabrics and 3D hydrogels by using textile techniques combined with bioactive hydrogel formation. Embedded nano-micro fibrous scaffolds within hydrogel enhanced mechanical strength and physical structural anisotropy of the composite scaffold (similar to native aortic valve leaflets) and also reduced its compaction. We determined that the composite scaffolds supported the growth of human aortic valve interstitial cells (HAVIC), balanced the remodeling of heart valve ECM against shrinkage, and maintained better physiological fibroblastic phenotype in both normal and diseased HAVIC over single materials. These fabricated composite scaffolds enable the engineering of a living heart valve graft with improved anisotropic structure and tissue biomechanics important for maintaining valve cell phenotypes.

  6. Development of generalized 3-D braiding machines for composite preforms

    NASA Technical Reports Server (NTRS)

    Huey, Cecil O., Jr.; Farley, Gary L.

    1993-01-01

    The operating principles of two prototype braiding machines for the production of generalized braid patterns are described. Both processes afford previously unachievable control of the interlacing of fibers within a textile structure that make them especially amenable to the fabrication of textile preforms for composite materials. They enable independent control of the motion of the individual fibers being woven, thereby enabling the greatest possible freedom in controlling fiber orientation within a structure. This freedom enables the designer to prescribe local fiber orientation to better optimize material performance. The processes have been implemented on a very small scale but at a level that demonstrates their practicality and the soundness of the principles governing their operation.

  7. Nano-Composite Material Development for 3-D Printers

    SciTech Connect

    Satches, Michael Randolph

    2015-10-14

    The objectives of the project was to create a graphene reinforced polymer nano-composite viable in a commercial 3-D printer; study the effects of ultra-high loading of graphene in polymer matrices; and determine the functional upper limit of graphene loading.

  8. An anisotropic constitutive model with biaxial-tension coupling for woven composite reinforcements

    NASA Astrophysics Data System (ADS)

    Yao, Yuan; Huang, Xiaoshuang; Peng, Xiongqi; Gong, Youkun

    2016-10-01

    Based on fiber reinforced continuum mechanics theory, an anisotropic hyperelastic constitutive model with biaxial tension coupling for woven composite reinforcements is developed. Experimental data from literature are used to identify material parameters in the constitutive model for a specific balanced plain woven fabric. The developed model is validated by comparing numerical results with experimental biaxial tension data under different stretch ratios and picture-frame shear data, demonstrating that the developed constitutive model is highly suitable to characterize the highly non-linear and strongly anisotropic mechanical behaviors of woven composite reinforcements under large deformation.

  9. Optimisation du tissage de composites orthogonaux 3D

    NASA Astrophysics Data System (ADS)

    Younes, Rafic; Aboura, Zoheir; Benzeggag, Malk

    2008-09-01

    This Note deals with an optimization study for the representative elementary volume (REV) of the 3D orthogonal reinforcement in order to suggest the internal geometry of wicks as well as the prediction of mechanical and damage properties under axial loading. The applied method of optimization is the one of the sequential quadratic programming (SQP). The mechanical properties are determined by a homogenization study based on the average sum of the rigidities of the constituents and the composite resistance is searched starting from the application of the 3D Tsai-Wu failure criterion. The proposition of the weaving is spotted by the internal geometry represented by the fibers volume fractions, their proportions in each direction and the weaving step of the vertical reinforcement. The results of this study are compared to experimental studies about 3D orthogonal with carbon reinforcements. To cite this article: R. Younes et al., C. R. Mecanique 336 (2008).

  10. Multimaterial magnetically assisted 3D printing of composite materials

    PubMed Central

    Kokkinis, Dimitri; Schaffner, Manuel; Studart, André R.

    2015-01-01

    3D printing has become commonplace for the manufacturing of objects with unusual geometries. Recent developments that enabled printing of multiple materials indicate that the technology can potentially offer a much wider design space beyond unusual shaping. Here we show that a new dimension in this design space can be exploited through the control of the orientation of anisotropic particles used as building blocks during a direct ink-writing process. Particle orientation control is demonstrated by applying low magnetic fields on deposited inks pre-loaded with magnetized stiff platelets. Multimaterial dispensers and a two-component mixing unit provide additional control over the local composition of the printed material. The five-dimensional design space covered by the proposed multimaterial magnetically assisted 3D printing platform (MM-3D printing) opens the way towards the manufacturing of functional heterogeneous materials with exquisite microstructural features thus far only accessible by biological materials grown in nature. PMID:26494528

  11. Multimaterial magnetically assisted 3D printing of composite materials

    NASA Astrophysics Data System (ADS)

    Kokkinis, Dimitri; Schaffner, Manuel; Studart, André R.

    2015-10-01

    3D printing has become commonplace for the manufacturing of objects with unusual geometries. Recent developments that enabled printing of multiple materials indicate that the technology can potentially offer a much wider design space beyond unusual shaping. Here we show that a new dimension in this design space can be exploited through the control of the orientation of anisotropic particles used as building blocks during a direct ink-writing process. Particle orientation control is demonstrated by applying low magnetic fields on deposited inks pre-loaded with magnetized stiff platelets. Multimaterial dispensers and a two-component mixing unit provide additional control over the local composition of the printed material. The five-dimensional design space covered by the proposed multimaterial magnetically assisted 3D printing platform (MM-3D printing) opens the way towards the manufacturing of functional heterogeneous materials with exquisite microstructural features thus far only accessible by biological materials grown in nature.

  12. Quantifying Effects of Voids in Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldsmith, Marlana B.; Sankar, Bhavani V.; Haftka, Raphael T.; Goldberg, Robert K.

    2013-01-01

    Randomness in woven ceramic matrix composite architecture has been found to cause large variability in stiffness and strength. The inherent voids are an aspect of the architecture that may cause a significant portion of the variability. A study is undertaken to investigate the effects of many voids of random sizes and distributions. Response surface approximations were formulated based on void parameters such as area and length fractions to provide an estimate of the effective stiffness. Obtaining quantitative relationships between the properties of the voids and their effects on stiffness of ceramic matrix composites are of ultimate interest, but the exploratory study presented here starts by first modeling the effects of voids on an isotropic material. Several cases with varying void parameters were modeled which resulted in a large amount of variability of the transverse stiffness and out-of-plane shear stiffness. An investigation into a physical explanation for the stiffness degradation led to the observation that the voids need to be treated as an entity that reduces load bearing capabilities in a space larger than what the void directly occupies through a corrected length fraction or area fraction. This provides explanation as to why void volume fraction is not the only important factor to consider when computing loss of stiffness.

  13. 3D Guided Wave Motion Analysis on Laminated Composites

    NASA Technical Reports Server (NTRS)

    Tian, Zhenhua; Leckey, Cara; Yu, Lingyu

    2013-01-01

    Ultrasonic guided waves have proved useful for structural health monitoring (SHM) and nondestructive evaluation (NDE) due to their ability to propagate long distances with less energy loss compared to bulk waves and due to their sensitivity to small defects in the structure. Analysis of actively transmitted ultrasonic signals has long been used to detect and assess damage. However, there remain many challenging tasks for guided wave based SHM due to the complexity involved with propagating guided waves, especially in the case of composite materials. The multimodal nature of the ultrasonic guided waves complicates the related damage analysis. This paper presents results from parallel 3D elastodynamic finite integration technique (EFIT) simulations used to acquire 3D wave motion in the subject laminated carbon fiber reinforced polymer composites. The acquired 3D wave motion is then analyzed by frequency-wavenumber analysis to study the wave propagation and interaction in the composite laminate. The frequency-wavenumber analysis enables the study of individual modes and visualization of mode conversion. Delamination damage has been incorporated into the EFIT model to generate "damaged" data. The potential for damage detection in laminated composites is discussed in the end.

  14. Instability and Wave Propagation in Structured 3D Composites

    NASA Astrophysics Data System (ADS)

    Kaynia, Narges; Fang, Nicholas X.; Boyce, Mary C.

    2014-03-01

    Many structured composites found in nature possess undulating and wrinkled interfacial layers that regulate mechanical, chemical, acoustic, adhesive, thermal, electrical and optical functions of the material. This research focused on the complex instability and wrinkling pattern arising in 3D structured composites and the effect of the buckling pattern on the overall structural response. The 3D structured composites consisted of stiffer plates supported by soft matrix on both sides. Compression beyond the critical strain led to complex buckling patterns in the initially straight plates. The motivation of our work is to elaborate the formation of a system of prescribed periodic scatterers (metamaterials) due to buckling, and their effect to interfere wave propagation through the metamaterial structures. Such metamaterials made from elastomers enable large reversible deformation and, as a result, significant changes of the wave propagation properties. We developed analytical and finite element models to capture various aspects of the instability mechanism. Mechanical experiments were designed to further explore the modeling results. The ability to actively alter the 3D composite structure can enable on-demand tunability of many different functions, such as active control of wave propagation to create band-gaps and waveguides.

  15. Nano-Composite Material Development for 3-D Printers

    SciTech Connect

    Satches, Michael Randolph

    2015-12-01

    Graphene possesses excellent mechanical properties with a tensile strength that may exceed 130 GPa, excellent electrical conductivity, and good thermal properties. Future nano-composites can leverage many of these material properties in an attempt to build designer materials for a broad range of applications. 3-D printing has also seen vast improvements in recent years that have allowed many companies and individuals to realize rapid prototyping for relatively low capital investment. This research sought to create a graphene reinforced, polymer matrix nano-composite that is viable in commercial 3D printer technology, study the effects of ultra-high loading percentages of graphene in polymer matrices and determine the functional upper limit for loading. Loadings varied from 5 wt. % to 50 wt. % graphene nanopowder loaded in Acrylonitrile Butadiene Styrene (ABS) matrices. Loaded sample were characterized for their mechanical properties using three point bending, tensile tests, as well as dynamic mechanical analysis.

  16. 3D Printing of Biocompatible Supramolecular Polymers and their Composites.

    PubMed

    Hart, Lewis R; Li, Siwei; Sturgess, Craig; Wildman, Ricky; Jones, Julian R; Hayes, Wayne

    2016-02-10

    A series of polymers capable of self-assembling into infinite networks via supramolecular interactions have been designed, synthesized, and characterized for use in 3D printing applications. The biocompatible polymers and their composites with silica nanoparticles were successfully utilized to deposit both simple cubic structures, as well as a more complex twisted pyramidal feature. The polymers were found to be not toxic to a chondrogenic cell line, according to ISO 10993-5 and 10993-12 standard tests and the cells attached to the supramolecular polymers as demonstrated by confocal microscopy. Silica nanoparticles were then dispersed within the polymer matrix, yielding a composite material which was optimized for inkjet printing. The hybrid material showed promise in preliminary tests to facilitate the 3D deposition of a more complex structure.

  17. Designing bioinspired composite reinforcement architectures via 3D magnetic printing

    NASA Astrophysics Data System (ADS)

    Martin, Joshua J.; Fiore, Brad E.; Erb, Randall M.

    2015-10-01

    Discontinuous fibre composites represent a class of materials that are strong, lightweight and have remarkable fracture toughness. These advantages partially explain the abundance and variety of discontinuous fibre composites that have evolved in the natural world. Many natural structures out-perform the conventional synthetic counterparts due, in part, to the more elaborate reinforcement architectures that occur in natural composites. Here we present an additive manufacturing approach that combines real-time colloidal assembly with existing additive manufacturing technologies to create highly programmable discontinuous fibre composites. This technology, termed as `3D magnetic printing', has enabled us to recreate complex bioinspired reinforcement architectures that deliver enhanced material performance compared with monolithic structures. Further, we demonstrate that we can now design and evolve elaborate reinforcement architectures that are not found in nature, demonstrating a high level of possible customization in discontinuous fibre composites with arbitrary geometries.

  18. Designing bioinspired composite reinforcement architectures via 3D magnetic printing

    PubMed Central

    Martin, Joshua J.; Fiore, Brad E.; Erb, Randall M.

    2015-01-01

    Discontinuous fibre composites represent a class of materials that are strong, lightweight and have remarkable fracture toughness. These advantages partially explain the abundance and variety of discontinuous fibre composites that have evolved in the natural world. Many natural structures out-perform the conventional synthetic counterparts due, in part, to the more elaborate reinforcement architectures that occur in natural composites. Here we present an additive manufacturing approach that combines real-time colloidal assembly with existing additive manufacturing technologies to create highly programmable discontinuous fibre composites. This technology, termed as ‘3D magnetic printing', has enabled us to recreate complex bioinspired reinforcement architectures that deliver enhanced material performance compared with monolithic structures. Further, we demonstrate that we can now design and evolve elaborate reinforcement architectures that are not found in nature, demonstrating a high level of possible customization in discontinuous fibre composites with arbitrary geometries. PMID:26494282

  19. Mechanical Characterization and Micromechanical Modeling of Woven Carbon/Copper Composites

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Pindera, Marek-Jerzy; Ellis, David L.; Miner, Robert V.

    1997-01-01

    The present investigation examines the in-plane mechanical behavior of a particular woven metal matrix composite (MMC); 8-harness (8H) satin carbon/copper (C/Cu). This is accomplished via mechanical testing as well as micromechanical modeling. While the literature is replete with experimental and modeling efforts for woven and braided polymer matrix composites, little work has been done on woven and braided MMC's. Thus, the development and understanding of woven MMC's is at an early stage. 8H satin C/Cu owes its existence to the high thermal conductivity of copper and low density and thermal expansion of carbon fibers. It is a candidate material for high heat flux applications, such as space power radiator panels. The experimental portion of this investigation consists of monotonic and cyclic tension, compression, and Iosipescu shear tests, as well as combined tension-compression tests. Tests were performed on composite specimens with three copper matrix alloy types: pure Cu, Cu-0.5 weight percent Ti (Cu-Ti), and Cu-0.7 weight percent Cr (Cu-Cr). The small alloying additions are present to promote fiber/matrix interfacial bonding. The analytical modeling effort utilizes an approach in which a local micromechanical model is embedded in a global micromechanical model. This approach differs from previously developed analytical models for woven composites in that a true repeating unit cell is analyzed. However, unlike finite element modeling of woven composites, the geometry is sufficiently idealized to allow efficient geometric discretization and efficient execution.

  20. Lightweight 3D cellular composites inspired by balsa.

    PubMed

    Malek, Sardar; Raney, Jordan R; Lewis, Jennifer A; Gibson, Lorna J

    2017-03-17

    Additive manufacturing technologies offer new ways to fabricate cellular materials with composite cell walls, mimicking the structure and mechanical properties of woods. However, materials limitations and a lack of design tools have confined the usefulness of 3D printed cellular materials. We develop new carbon fiber reinforced, epoxy inks for 3D printing which result in printed materials with longitudinal Young's modulus up to 57 GPa (exceeding the longitudinal modulus of wood cell wall material). To guide the design of hierarchical cellular materials, we developed a parameterized, multi-scale, finite element model. Computational homogenization based on finite element simulations at multiple length scales is employed to obtain the elastic properties of the material at multiple length scales. Parameters affecting the elastic response of cellular composites, such as the volume fraction, orientation distribution, and aspect ratio of fibers within the cell walls as well as the cell geometry and relative density are included in the model. To validate the model, experiments are conducted on both solid carbon fiber/epoxy composites and cellular structures made from them, showing excellent agreement with computational multi-scale model predictions, both at the cell-wall and at the cellular-structure levels. Using the model, cellular structures are designed and experimentally shown to achieve a specific stiffness nearly as high as that observed in balsa wood. The good agreement between the multi-scale model predictions and experimental data provides confidence in the practical utility of this model as a tool for designing novel 3D cellular composites with unprecedented specific elastic properties.

  1. Effects of assumed tow architecture on the predicted moduli and stresses in woven composites

    NASA Technical Reports Server (NTRS)

    Chapman, Clinton Dane

    1994-01-01

    This study deals with the effect of assumed tow architecture on the elastic material properties and stress distributions of plain weave woven composites. Specifically, the examination of how a cross-section is assumed to sweep-out the tows of the composite is examined in great detail. The two methods studied are extrusion and translation. This effect is also examined to determine how sensitive this assumption is to changes in waviness ratio. 3D finite elements were used to study a T300/Epoxy plain weave composite with symmetrically stacked mats. 1/32nd of the unit cell is shown to be adequate for analysis of this type of configuration with the appropriate set of boundary conditions. At low waviness, results indicate that for prediction of elastic properties, either method is adequate. At high waviness, certain elastic properties become more sensitive to the method used. Stress distributions at high waviness ratio are shown to vary greatly depending on the type of loading applied. At low waviness, both methods produce similar results.

  2. Woven type smart soft composite beam with in-plane shape retention

    NASA Astrophysics Data System (ADS)

    Wu, Renzhe; Han, Min-Woo; Lee, Gil-Yong; Ahn, Sung-Hoon

    2013-12-01

    Shape memory alloy (SMA) wire embedded composites (SMAECs) are widely used as morphing structures in small-size and high-output systems. However, conventional SMAECs cannot keep deformed shapes without additional energy. In this paper, a new kind of smart structure named the woven type smart soft composite (SSC) beam is introduced, which is not only capable of morphing, but also maintaining its deformed shape without additional energy. The woven type SSC beam consists of two parts: woven wires and matrix. The selected woven wires are nitinol (Ni-Ti) SMA wires and glass fibers, while the matrix part is polydimethylsiloxane (PDMS). In order to evaluate the performance of the woven type SSC beam in areas such as in-plane deformation, blocking force and repeatability, a beam-shape specimen is prepared of size 100 mm (length) × 8 mm (width) ×3 mm (thickness). The fabricated SSC beam achieved 21 mm deformation and 16 mm shape retention. Blocking force was measured using a dynamometer, and was about 60 mN. In the repeatability test, it recovered almost the same position when its cooling time was 90 s more. Consequently, the woven type SSC beam can be applied to bio-mimicking, soft morphing actuators, consuming less energy than traditional SMAECs.

  3. An Analytical Model for Predicting Stab Resistance of Flexible Woven Composites

    NASA Astrophysics Data System (ADS)

    Hou, Limin; Sun, Baozhong; Gu, Bohong

    2013-08-01

    Flexible woven composites have been widely used in geotextiles and light weight building structures. The stab resistance behavior of the flexible woven composite is an important factor for the application design. This paper reports an analytical model for predicting stab resistance of flexible woven composites under perpendicular stab with a blunt steel penetrator. The analytical model was established based on the microstructure and the deformation shape of the flexible woven composite under normal penetration. During the quasi-static stab penetration, the strain energies of warp and weft yarns and resins have been calculated. The stab resistance was calculated from the strain energies of the flexible woven composite. Furthermore, the contributions of the warp and weft yarns, resins to the stab resistance have been analyzed. It was found the three constituents have near the same contribution to the stab resistance. The higher value of weaving density, strength of yarns and especially the higher strength coating resins will lead the higher stab resistance. With the analytical model, the stab resistance would be expected to be designed in an efficient way with an acceptable precision.

  4. Microfibrous β-TCP/collagen scaffolds mimic woven bone in structure and composition.

    PubMed

    Zhang, Shen; Zhang, Xin; Cai, Qing; Wang, Bo; Deng, Xuliang; Yang, Xiaoping

    2010-12-01

    Woven bone, as the initial form of bone tissue, is always found in developing and repairing bone. It is thought of as a temporary scaffold for the deposition of osteogenic cells and the laying down of lamellar bone. Thus, we hypothesize that a matrix which resembles the architecture and components of woven bone can provide an osteoblastic microenvironment for bone cell growth and new bone formation. In this study, woven-bone-like beta-tricalcium phosphate (β-TCP)/collagen scaffolds were fabricated by sol-gel electrospinning and impregnating methods. Optimization studies on sol-gel synthesis and electrospinning process were conducted respectively to prepare pure β-TCP fibers with dimensions close to mineralized collagen fibrils in woven bone. The collagen-coating layer prepared by impregnation had an adhesive role that held the β-TCP fibers together, and resulted in rapid degradation and matrix mineralization in in vitro tests. MG63 osteoblast-like cells seeded on the resultant scaffolds showed three-dimensional (3D) morphologies, and merged into multicellular layers after 7 days culture. Cytotoxicity test further revealed that extracts from the resultant scaffolds could promote the proliferation of MG63 cells. Therefore, the woven-bone-like matrix that we constructed favored the attachment and proliferation of MG63 cells in three dimensions. It has great potential ability to shorten the time of formation of new bone.

  5. Micromechanics of fatigue in woven and stitched composites

    NASA Technical Reports Server (NTRS)

    Cox, B. N.; Dadkhah, M. S.; Inman, R. V.; Mitchell, M. R.; Morris, W. L.; Schroeder, S.

    1991-01-01

    The goal is to determine how microstructural factors, especially the architecture of microstructural factors, control fatigue damage in 3D reinforced polymer composites. Test materials were fabricated from various preforms, including stitched quasi-isotropic laminates, and through-the-thickness angle interlock, layer-to-layer angle interlock, and through-the-thickness stitching effect weaves. Preforms were impregnated with a tough resin by a special vacuum infiltration method. Most tests are being performed in uniaxial compression/compression loading. In all cases to date, failure has occurred not by delamination, but by shear failure, which occurs suddenly rather than by gradual macroscopic crack growth. Some theoretical aspects of bridging are also examined.

  6. Mesoscopic Strains Maps in Woven Composite Laminas During Off-axis Tension

    NASA Astrophysics Data System (ADS)

    Anzelotti, G.; Nicoletto, G.; Riva, E.

    2010-06-01

    The mechanics of woven carbon-fiber reinforced plastic (CFRP) composites is influenced by the complex architecture of the reinforcement phase. Computational (i.e. finite element based) approaches have been used increasingly to model not only the global laminate stiffness, but also damage evolution and laminate strength. The modeling combines the identification of the architectural unit cell (UC), the selection of suitable constitutive models of the different phases, the creation of a fine discretization of the UC in finite elements, the application of an incremental solution procedure that solves iteratively for the stresses and strains in the UC, [1]. The experimental validation of computational models is carried out mainly at the macroscopical level, i.e. simulation of the macroscopic stress-strain curve. Damage, however, is a localized, straindependent phenomenon and therefore only accurate strain distribution within the UC (at the mesolevel) can identify critical conditions in terms of damage location, extension and evolution. The validation of computational damage procedures is a key task and full-field optical strain analysis methods appear the ideal instrument. However, only limited examples of direct finte element method (FEM) vs experimental strain correlation are found because of the limited sensitivity and spatial resolution of some techniques and the complexity and applicative difficulty of others. The aim of the present paper is to present the application of the digital image correlation (DIC) technique, [2], to the full-field strain analysis at the mesoscopic level (i.e. within the UC) of a woven CFRP lamina when the direction of loading forms an angle to the material direction. The material under consideration is a woven carbon fiber reinforced epoxy composite. Orthogonal yarns, each made of of several thousand fibers, are woven according the twill-weave architecture is shown in Fig. 1a. Single-ply laminas were manufactured and tested to eliminate

  7. Impact Strength of Different Weaving Patterns of Woven Kenaf Reinforced Polyester Composites

    NASA Astrophysics Data System (ADS)

    Khalid, S. N. A.; Ismail, A. E.; Zainulabidin, M. H.

    2017-01-01

    This paper focuses on the effect of weaving patterns and orientations on the energy absorption of woven kenaf reinforced polyester composites. Kenaf fiber in the form of yarn is weaved to produce different weaving patterns such as plain, twill and basket. Three woven mats are stacked together and mixed with polyester resin before it is compressed to squeeze out any excessive resin. There is 9 different orientations are used during stacking processes. The hardened composites are cured for 24 hours before it is shaped according to specific dimensions for imp act tests. The composites are perforated with 1m/s blunted projectile. According to the experimental findings, both weaving patterns and orientations have distinct potential effects on the force-displacement diagrams. However, fiber orientations have insignificant effect for plain woven especially in the first stage of deformations. Energy absorption performances for each composite condition are calculated and then plotted against fiber orientations for different weaving patterns. It is found there is no strong relationship between energy absorption and fiber orientations. However for each case of composites, higher energy absorption is found for the composites orientated using [+40°/-15°/+40°/+75°]. Based on the fracture observation, both plain and basket-type woven composites reveal large fragmentations occurred indicating lower energy absorption performances. While for twill condition, no obvious fragmentation is observed where the impact damage around the perforated hole is uniformly distributed leading to higher capability of energy absorptions.

  8. Effect of carbon nanotube addition on the wear behavior of basalt/epoxy woven composites.

    PubMed

    Kim, M T; Rhee, K Y; Lee, B H; Kim, C J

    2013-08-01

    The effect of acid-treated carbon nanotube (CNT) addition on the wear and dynamic mechanical thermal properties of basalt/epoxy woven composites was investigated in this study. Basalt/CNT/epoxy composites were fabricated by impregnating woven basalt fibers into epoxy resin mixed with 1 wt% CNTs which were acid-treated. Wear and DMA (dynamic mechanical analyzer) tests were performed on basalt/epoxy composites and basalt/CNT/epoxy composites. The results showed that the addition of the acid-treated CNTs improved the wear properties of basalt/epoxy woven composites. Specifically, the friction coefficient of the basalt/epoxy composite was stabilized in the range of 0.5-0.6 while it fell in the range of 0.3-0.4 for basalt/CNT/epoxy composites. The wear volume loss of the basalt/CNT/epoxy composites was approximately 68% lower than that of the basalt/epoxy composites. The results also showed that the glass transition temperature of basalt/CNT/epoxy composites was higher than that of basalt/epoxy composites. The improvement of wear properties of basalt/epoxy composites by the addition of acid-treated CNTs was caused by the homogeneous load transfer between basalt fibers and epoxy matrix due to the reinforcement of CNTs.

  9. Composite panels based on woven sandwich-fabric preforms

    NASA Astrophysics Data System (ADS)

    van Vuure, Aart Willem

    A new type of sandwich material was investigated, based on woven sandwich-fabric preforms. Because of the integrally woven nature of the sandwich-fabric the skin-core debonding resistance of panels and structures based on the preform is very high. As the sandwich-fabrics are produced by a large scale textile weaving process (velvet weaving or distance weaving) and already a preform of a sandwich is available, the cost of the final panel or structure can potentially stay limited. Most attention in this work is focussed on the mechanical performance of sandwich-fabric panels. The high skin-core debonding resistance was verified and also indications were found of a good damage tolerance. Both unfoamed and foamed panels were evaluated and compared with existing sandwich panels. Microstructural parameters investigated for unfoamed cores are pile length, pile density, woven pile angles, degree of pile stretching, tilt angles of the piles induced during panel production and resin content and distribution. For foamed panels it is especially the foam density which has an important influence. There appears to be a synergistic effect between piles and foam in the sandwich core, leading to very acceptable mechanical properties. For panels for (semi) structural applications, foaming is almost indispensable once the panel thickness is higher than about 15 mm. To understand the behaviour of foamed panels, attention was paid to the modelling of the mechanics of pure foam. The foam microstructure was modelled with the model of an anisotropic tetrakaidecahedron. The mechanical properties of unfoamed panels were modelled with the help of finite elements. A detailed geometrical description of the core layout was made which was incorporated into a preprocessing program for a finite element code. Attention is paid to the production of panels based on the woven preforms. A newly developed Adhesive Foil Stretching process was investigated. Also the foaming of panels was studied. A lot of

  10. Through-the-thickness properties of three-dimensionally woven carbon/epoxy composites

    SciTech Connect

    Hartranft, D.; Parvizi-Majidi, A.

    1994-12-31

    A multi-section specimen has been designed and used for the direct measurement of the through-the-thickness tensile properties of three-dimensionally woven carbon/epoxy composites. Design optimization was conducted through the analysis of the stress fields using a two-dimensional boundary element method. three woven architectures were studied: a layer-to-layer angle interlock, a through-the-thickness angle interlock, and through-the-thickness orthogonal weave. All the preforms were infiltrated by the resin transfer molding technique. Several configurations of the multi-section specimen were tested and the results verified the findings of the numerical analyses.

  11. High-strength cellular ceramic composites with 3D microarchitecture

    PubMed Central

    Bauer, Jens; Hengsbach, Stefan; Tesari, Iwiza; Schwaiger, Ruth; Kraft, Oliver

    2014-01-01

    To enhance the strength-to-weight ratio of a material, one may try to either improve the strength or lower the density, or both. The lightest solid materials have a density in the range of 1,000 kg/m3; only cellular materials, such as technical foams, can reach considerably lower values. However, compared with corresponding bulk materials, their specific strength generally is significantly lower. Cellular topologies may be divided into bending- and stretching-dominated ones. Technical foams are structured randomly and behave in a bending-dominated way, which is less weight efficient, with respect to strength, than stretching-dominated behavior, such as in regular braced frameworks. Cancellous bone and other natural cellular solids have an optimized architecture. Their basic material is structured hierarchically and consists of nanometer-size elements, providing a benefit from size effects in the material strength. Designing cellular materials with a specific microarchitecture would allow one to exploit the structural advantages of stretching-dominated constructions as well as size-dependent strengthening effects. In this paper, we demonstrate that such materials may be fabricated. Applying 3D laser lithography, we produced and characterized micro-truss and -shell structures made from alumina–polymer composite. Size-dependent strengthening of alumina shells has been observed, particularly when applied with a characteristic thickness below 100 nm. The presented artificial cellular materials reach compressive strengths up to 280 MPa with densities well below 1,000 kg/m3. PMID:24550268

  12. Evaluation of Solid Modeling Software for Finite Element Analysis of Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Nemeth, Noel N.; Mital, Subodh; Lang, Jerry

    2010-01-01

    Three computer programs, used for the purpose of generating 3-D finite element models of the Repeating Unit Cell (RUC) of a textile, were examined for suitability to model woven Ceramic Matrix Composites (CMCs). The programs evaluated were the open-source available TexGen, the commercially available WiseTex, and the proprietary Composite Material Evaluator (COMATE). A five-harness-satin (5HS) weave for a melt-infiltrated (MI) silicon carbide matrix and silicon carbide fiber was selected as an example problem and the programs were tested for their ability to generate a finite element model of the RUC. The programs were also evaluated for ease-of-use and capability, particularly for the capability to introduce various defect types such as porosity, ply shifting, and nesting of a laminate. Overall, it was found that TexGen and WiseTex were useful for generating solid models of the tow geometry; however, there was a lack of consistency in generating well-conditioned finite element meshes of the tows and matrix. TexGen and WiseTex were both capable of allowing collective and individual shifting of tows within a ply and WiseTex also had a ply nesting capability. TexGen and WiseTex were sufficiently userfriendly and both included a Graphical User Interface (GUI). COMATE was satisfactory in generating a 5HS finite element mesh of an idealized weave geometry but COMATE lacked a GUI and was limited to only 5HS and 8HS weaves compared to the larger amount of weave selections available with TexGen and WiseTex.

  13. Optimization on Impact Strength of Woven Kenaf Reinforced Polyester Composites using Taguchi Method

    NASA Astrophysics Data System (ADS)

    Khalid, S. N. A.; Ismail, A. E.; Zainulabidin, M. H.

    2017-01-01

    This paper focuses on the effect of weaving patterns and orientations on the energy absorption of woven kenaf reinforced polyester composites. Kenaf fiber in the form of yarn is weaved to produce different weaving patterns such as plain, twill and basket. Three woven mats are stacked together and mixed with polyester resin before it is compressed to squeeze out any excessive resin. There is nine different orientations are used during stacking processes by following Taguchi orthogonal arrays method. The hardened composites are cured for 24 hours before it is shaped according to specific dimensions for impact tests. The composites are perforated with 1m/s blunted projectile. According to the experimental findings, weaving pattern and orientation have distinct potential effects on value of energy absorption. The optimization using Taguchi method reveals preferable orientation of each weaving pattern composites. Based on the fracture observation, the fragmentations after optimization indicating lower distance surface fracture perforated obtained.

  14. Modeling the Elastic Modulus of 2D Woven CVI SiC Composites

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.

    2006-01-01

    The use of fiber, interphase, CVI SiC minicomposites as structural elements for 2D-woven SiC fiber reinforced chemically vapor infiltrated (CVI) SiC matrix composites is demonstrated to be a viable approach to model the elastic modulus of these composite systems when tensile loaded in an orthogonal direction. The 0deg (loading direction) and 90deg (perpendicular to loading direction) oriented minicomposites as well as the open porosity and excess SiC associated with CVI SiC composites were all modeled as parallel elements using simple Rule of Mixtures techniques. Excellent agreement for a variety of 2D woven Hi-Nicalon(TradeMark) fiber-reinforced and Sylramic-iBN reinforced CVI SiC matrix composites that differed in numbers of plies, constituent content, thickness, density, and number of woven tows in either direction (i.e, balanced weaves versus unbalanced weaves) was achieved. It was found that elastic modulus was not only dependent on constituent content, but also the degree to which 90deg minicomposites carried load. This depended on the degree of interaction between 90deg and 0deg minicomposites which was quantified to some extent by composite density. The relationships developed here for elastic modulus only necessitated the knowledge of the fractional contents of fiber, interphase and CVI SiC as well as the tow size and shape. It was concluded that such relationships are fairly robust for orthogonally loaded 2D woven CVI SiC composite system and can be implemented by ceramic matrix composite component modelers and designers for modeling the local stiffness in simple or complex parts fabricated with variable constituent contents.

  15. Numerical study on 3D composite morphing actuators

    NASA Astrophysics Data System (ADS)

    Oishi, Kazuma; Saito, Makoto; Anandan, Nishita; Kadooka, Kevin; Taya, Minoru

    2015-04-01

    There are a number of actuators using the deformation of electroactive polymer (EAP), where fewer papers seem to have focused on the performance of 3D morphing actuators based on the analytical approach, due mainly to their complexity. The present paper introduces a numerical analysis approach on the large scale deformation and motion of a 3D half dome shaped actuator composed of thin soft membrane (passive material) and EAP strip actuators (EAP active coupon with electrodes on both surfaces), where the locations of the active EAP strips is a key parameter. Simulia/Abaqus Static and Implicit analysis code, whose main feature is the high precision contact analysis capability among structures, are used focusing on the whole process of the membrane to touch and wrap around the object. The unidirectional properties of the EAP coupon actuator are used as input data set for the material properties for the simulation and the verification of our numerical model, where the verification is made as compared to the existing 2D solution. The numerical results can demonstrate the whole deformation process of the membrane to wrap around not only smooth shaped objects like a sphere or an egg, but also irregularly shaped objects. A parametric study reveals the proper placement of the EAP coupon actuators, with the modification of the dome shape to induce the relevant large scale deformation. The numerical simulation for the 3D soft actuators shown in this paper could be applied to a wider range of soft 3D morphing actuators.

  16. Tensile and Laterally Confined Compression Properties of Various 3-Dimensional (3-D) Woven Composites

    DTIC Science & Technology

    2014-11-01

    3 Fig. 3 Schematic of VARTM setup...Fabrication and Void Content 4.1 Infusion The panels were made using a vacuum-assisted resin transfer molding ( VARTM ) system. Figure 3 illustrates...a schematic of VARTM process. There are many benefits to this process, some of which include shorter mold time, lower tooling costs, reduced volatile

  17. Rail Shear and Short Beam Shear Properties of Various 3-Dimensional (3-D) Woven Composites

    DTIC Science & Technology

    2016-01-01

    from stress-strain response. A 0.2% plastic strain offset method was used to calculate the yield of the material. Table 4 compares the maximum... plastic region where the progressive damages began to form in the samples. Based on the stress-strain curves, it was notable that the 12° configuration...outperformed the other architectures in terms of shear strength and moduli. Another observation made from the curvatures was that the plastic portion

  18. Axial quasi-static crushing behaviour of cylindrical woven kenaf fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Abdullah, Noorhaslinda; Ismail, Al Emran

    2017-01-01

    This paper presents the crushing responses of cylindrical woven kenaf fibre reinforced composites under quasi-static compression. Kenaf fiber in the form of yarn is weaved into woven mat. It is then submerged into polyester bath before it is wrapped into a cylindrical shape. There are two important parameters investigated such as number of layers and fiber orientations. According to the experimental results, as expected increasing the number of layers increased the energy absorption performances. However, increasing the fibre orientations from 0o to 45o capable to decrease the energy absorption capability. It is also observed that during progressive collapses, localized buckling is the dominant failure mechanism where there is no large composite fragmentation occurred.

  19. Graphene/polyaniline woven fabric composite films as flexible supercapacitor electrodes.

    PubMed

    Zang, Xiaobei; Li, Xiao; Zhu, Miao; Li, Xinming; Zhen, Zhen; He, Yijia; Wang, Kunlin; Wei, Jinquan; Kang, Feiyu; Zhu, Hongwei

    2015-04-28

    We report the design and preparation of graphene and polyaniline (PANI) woven-fabric composite films by in situ electropolymerization. The introduction of PANI greatly improves the electrochemical properties of solid-state supercapacitors which possess capacitances as high as 23 mF cm(-2), and exhibit excellent cycling stability with ∼ 100% capacitance retention after 2000 cycles. The devices have displayed superior flexibility with improved areal specific capacitances to 118% during deformation.

  20. Effects of Crimped Fiber Paths on Mixed Mode Delamination Behaviors in Woven Fabric Composites

    DTIC Science & Technology

    2016-09-01

    Andrew W. Hulton Melvin W. Jee Mahmoud Salama 5.d PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND...ADDRESS(ES) Naval Undersea Warfare Center Division 1176 Howell Street Newport, RI 02841-1708 8. PERFORMING ORGANIZATION REPORT NUMBER...toughness and crack propagation behaviors of woven fabric polymer composite laminates subjected to single- and mixed-mode loadings using numerical models

  1. Automated 3D structure composition for large RNAs

    PubMed Central

    Popenda, Mariusz; Szachniuk, Marta; Antczak, Maciej; Purzycka, Katarzyna J.; Lukasiak, Piotr; Bartol, Natalia; Blazewicz, Jacek; Adamiak, Ryszard W.

    2012-01-01

    Understanding the numerous functions that RNAs play in living cells depends critically on knowledge of their three-dimensional structure. Due to the difficulties in experimentally assessing structures of large RNAs, there is currently great demand for new high-resolution structure prediction methods. We present the novel method for the fully automated prediction of RNA 3D structures from a user-defined secondary structure. The concept is founded on the machine translation system. The translation engine operates on the RNA FRABASE database tailored to the dictionary relating the RNA secondary structure and tertiary structure elements. The translation algorithm is very fast. Initial 3D structure is composed in a range of seconds on a single processor. The method assures the prediction of large RNA 3D structures of high quality. Our approach needs neither structural templates nor RNA sequence alignment, required for comparative methods. This enables the building of unresolved yet native and artificial RNA structures. The method is implemented in a publicly available, user-friendly server RNAComposer. It works in an interactive mode and a batch mode. The batch mode is designed for large-scale modelling and accepts atomic distance restraints. Presently, the server is set to build RNA structures of up to 500 residues. PMID:22539264

  2. Automated 3D structure composition for large RNAs.

    PubMed

    Popenda, Mariusz; Szachniuk, Marta; Antczak, Maciej; Purzycka, Katarzyna J; Lukasiak, Piotr; Bartol, Natalia; Blazewicz, Jacek; Adamiak, Ryszard W

    2012-08-01

    Understanding the numerous functions that RNAs play in living cells depends critically on knowledge of their three-dimensional structure. Due to the difficulties in experimentally assessing structures of large RNAs, there is currently great demand for new high-resolution structure prediction methods. We present the novel method for the fully automated prediction of RNA 3D structures from a user-defined secondary structure. The concept is founded on the machine translation system. The translation engine operates on the RNA FRABASE database tailored to the dictionary relating the RNA secondary structure and tertiary structure elements. The translation algorithm is very fast. Initial 3D structure is composed in a range of seconds on a single processor. The method assures the prediction of large RNA 3D structures of high quality. Our approach needs neither structural templates nor RNA sequence alignment, required for comparative methods. This enables the building of unresolved yet native and artificial RNA structures. The method is implemented in a publicly available, user-friendly server RNAComposer. It works in an interactive mode and a batch mode. The batch mode is designed for large-scale modelling and accepts atomic distance restraints. Presently, the server is set to build RNA structures of up to 500 residues.

  3. The possibility of E-glass woven roving as reinforcement of GFRP composite sheet roof

    NASA Astrophysics Data System (ADS)

    Setyanto, Djoko

    2016-03-01

    The 1.25 mm thickness of opaque glass fiber reinforced polymer (GFRP) composite sheet roof that is produced by an Indonesia company at Tangerang, consists of two layers of 300 g/m2 E-glass chopped strand mat as reinforcement and unsaturated polyester resin as matrix. A layer of 300 g/m2 E-glass chopped strand mat is replaced by a layer of 400 g/m2 E-glass woven roving as reinforcement to study the possibility use as sheet roof material. The properties of the two samples of GFRP composite materials were compared. Barcol hardness and flexure strength of the two samples relatively not significance change. Tensile strength and elastic modulus of the new sample which contains a layer of woven roving reinforcement is greater than the other one. On the other hand the waviness of the new sample is greater, but cheaper. In general, a layer of E-glass woven roving and a layer of E-glass chopped strand mat can be considered as an alternative reinforcement of two layers reinforcement of GFRP composite material of sheet roof.

  4. Cloning Nacre's 3D Interlocking Skeleton in Engineering Composites to Achieve Exceptional Mechanical Properties.

    PubMed

    Zhao, Hewei; Yue, Yonghai; Guo, Lin; Wu, Juntao; Zhang, Youwei; Li, Xiaodong; Mao, Shengcheng; Han, Xiaodong

    2016-07-01

    Ceramic/polymer composite equipped with 3D interlocking skeleton (3D IL) is developed through a simple freeze-casting method, exhibiting exceptionally light weight, high strength, toughness, and shock resistance. Long-range crack energy dissipation enabled by 3D interlocking structure is considered as the primary reinforcing mechanism for such superior properties. The smart composite design strategy should hold a place in developing future structural engineering materials.

  5. Computational simulation of surface waviness in graphite/epoxy woven composites due to initial curing

    NASA Technical Reports Server (NTRS)

    Sanfeliz, Jose G.; Murthy, Pappu L. N.; Chamis, Christos C.

    1992-01-01

    Several models simulating plain weave, graphite/epoxy woven composites are presented, along with the effects that the simultaneous application of pressure and thermal loads have on their surfaces. The surface effects created by moisture absorption are also examined. The computational simulation consisted of using a two-dimensional finite element model for the composite. The properties of the finite element (FE) model are calculated by using the in-house composite mechanics computer code ICAN (Integrated Composite ANalyzer). MSC/NASTRAN is used for the FE analysis which yields the composite's top surface normalized displacements. These results demonstrate the importance of parameters such as the cure temperature (T sub o) and the resin content in the curing process of polymer-matrix composites. The modification of these parameters will help tailor the composite system to the desired requirements and applications.

  6. Simulation of Degraded Properties of 2D plain Woven C/SiC Composites under Preloading Oxidation Atmosphere

    NASA Astrophysics Data System (ADS)

    Chen, Xihui; Sun, Zhigang; Sun, Jianfen; Song, Yingdong

    2017-02-01

    In this paper, a numerical model which incorporates the oxidation damage model and the finite element model of 2D plain woven composites is presented for simulation of the oxidation behaviors of 2D plain woven C/SiC composite under preloading oxidation atmosphere. The equal proportional reduction method is firstly proposed to calculate the residual moduli and strength of unidirectional C/SiC composite. The multi-scale method is developed to simulate the residual elastic moduli and strength of 2D plain woven C/SiC composite. The multi-scale method is able to accurately predict the residual elastic modulus and strength of the composite. Besides, the simulated residual elastic moduli and strength of 2D plain woven C/SiC composites under preloading oxidation atmosphere show good agreements with experimental results. Furthermore, the preload, oxidation time, temperature and fiber volume fractions of the composite are investigated to show their influences upon the residual elastic modulus and strength of 2D plain woven C/SiC composites.

  7. Processing Optimization of Deformed Plain Woven Thermoplastic Composites

    NASA Astrophysics Data System (ADS)

    Smith, John R.; Vaidya, Uday K.

    2013-12-01

    This research addresses the processing optimization of post-manufactured, plain weave architecture composite panels consisted of four glass layers and thermoplastic polyurethane (TPU) when formed with only localized heating. Often times, during the production of deep drawn composite parts, a fabric preform experiences various defects, including non-isothermal heating and thickness variations. Minimizing these defects is of utmost importance for mass produceability in a practical manufacturing process. The broad objective of this research was to implement a design of experiments approach to minimize through-thickness composite panel variation during manufacturing by varying the heating time, the temperature of heated components and the clamping pressure. It was concluded that the heated tooling with least area contact was most influential, followed by the length of heating time and the amount of clamping pressure.

  8. Complementary methods for nondestructive testing of composite materials reinforced with carbon woven fibers

    NASA Astrophysics Data System (ADS)

    Steigmann, R.; Iftimie, N.; Sturm, R.; Vizureanu, P.; Savin, A.

    2015-11-01

    This paper presents complementary methods used in nondestructive evaluation (NDE) of composite materials reinforced with carbon woven fibers as two electromagnetic methods using sensor with orthogonal coils and sensor with metamaterials lens as well as ultrasound phased array method and Fiber Bragg gratings embedded instead of a carbon fiber for better health monitoring. The samples were impacted with low energy in order to study delamination influence. The electromagnetic behavior of composite was simulated by finite- difference time-domain (FDTD) software, showing a very good concordance with electromagnetic nondestructive evaluation tests.

  9. Stiffness and internal stresses of woven-fabric composites at low temperatures

    SciTech Connect

    Kriz, R.D.

    1984-01-01

    Woven-fabric composites are used in superconducting magnets and in containment of cryogenic liquids. Here, the mechanical response of a plain-weave laminated composite at cryogenic temperatures is studied by predicting the load-deformation response of a fundamental unit cell. At present, only tensile loads are studied in the warp direction. Results show that stresses normal to the warp-fill interface increase with increasing warp angle; the largest effect occurs in the matrix region. Thermal loads increase these stresses in the matrix region and decrease these stresses in the fill region. Stiffness increases with decreasing warp angle.

  10. Application of a Fiber Optic Distributed Strain Sensor System to Woven E-Glass Composite

    NASA Technical Reports Server (NTRS)

    Anastasi, Robert F.; Lopatin, Craig

    2001-01-01

    A distributed strain sensing system utilizing a series of identically written Bragg gratings along an optical fiber is examined for potential application to Composite Armored Vehicle health monitoring. A vacuum assisted resin transfer molding process was used to fabricate a woven fabric E-glass/composite panel with an embedded fiber optic strain sensor. Test samples machined from the panel were mechanically tested in 4-point bending. Experimental results are presented that show the mechanical strain from foil strain gages comparing well to optical strain from the embedded sensors. Also, it was found that the distributed strain along the sample length was consistent with the loading configuration.

  11. Effects of Weave Styles and Crimp Gradients on Damage Tolerance and Energy-Absorption Capacities of Woven Kevlar/Epoxy Composites

    DTIC Science & Technology

    2015-09-01

    ORGANIZATION NAME(S) AND ADDRESS(ES) Naval Undersea Warfare Center Division 1176 Howell Street Newport, Rl 02841-1708 8. PERFORMING ORGANIZATION ...gradients (CGs) on the damage-tolerance levels and energy-absorption capacities of woven fabric-reinforced polymer (WFRP) composites. A comparative...Mechanics Fabrics Finite Element Analysis Functionally Graded Impact Fracture Kevlar Woven Composites Woven Fabric-Reinforced Polymer Composites 16

  12. Low Temperature Thermal Conductivity of Woven Fabric Glass Fibre Composites

    NASA Astrophysics Data System (ADS)

    Kanagaraj, S.; Pattanayak, S.

    2004-06-01

    Fibre reinforced composites are replacing conventional materials due to its compatible and superior properties at low temperatures. Transverse thermal conductivity of plain fabric E-glass/Epoxy composites with the fibre concentrations of 32.5%, 35.2%, 39.2% and 48.9% has been studied in a GM-refrigerator based experimental setup using guarded hotplate technique. Experiments are carried out with the sets of stability criteria. This paper presents the investigation of the influence of the fibre concentration and temperature on the thermal conductivity of fabric composites from 30 K to 300K. It is observed from the experimental results that thermal conductivity increases with the increase of temperature and also with fibre concentration with different rate in different temperature range. The series model has been used to predict the thermal conductivity and compared with the experimental results. It is observed that below the crossover temperature of the composites, which varies from 150-225K depending upon their fibre concentration, the experimental results are within 10% with that of predicted values. The possible causes of variation are analyzed. The physical phenomenon behind the temperature dependence of thermal conductivity is discussed in detail.

  13. Low Temperature Thermal Conductivity of Woven Fabric Glass Fibre Composites

    SciTech Connect

    Kanagaraj, S.; Pattanayak, S.

    2004-06-28

    Fibre reinforced composites are replacing conventional materials due to its compatible and superior properties at low temperatures. Transverse thermal conductivity of plain fabric E-glass/Epoxy composites with the fibre concentrations of 32.5%, 35.2%, 39.2% and 48.9% has been studied in a GM-refrigerator based experimental setup using guarded hotplate technique. Experiments are carried out with the sets of stability criteria. This paper presents the investigation of the influence of the fibre concentration and temperature on the thermal conductivity of fabric composites from 30 K to 300K. It is observed from the experimental results that thermal conductivity increases with the increase of temperature and also with fibre concentration with different rate in different temperature range. The series model has been used to predict the thermal conductivity and compared with the experimental results. It is observed that below the crossover temperature of the composites, which varies from 150-225K depending upon their fibre concentration, the experimental results are within 10% with that of predicted values. The possible causes of variation are analyzed. The physical phenomenon behind the temperature dependence of thermal conductivity is discussed in detail.

  14. Prostate Mechanical Imaging: 3-D Image Composition and Feature Calculations

    PubMed Central

    Egorov, Vladimir; Ayrapetyan, Suren; Sarvazyan, Armen P.

    2008-01-01

    We have developed a method and a device entitled prostate mechanical imager (PMI) for the real-time imaging of prostate using a transrectal probe equipped with a pressure sensor array and position tracking sensor. PMI operation is based on measurement of the stress pattern on the rectal wall when the probe is pressed against the prostate. Temporal and spatial changes in the stress pattern provide information on the elastic structure of the gland and allow two-dimensional (2-D) and three-dimensional (3-D) reconstruction of prostate anatomy and assessment of prostate mechanical properties. The data acquired allow the calculation of prostate features such as size, shape, nodularity, consistency/hardness, and mobility. The PMI prototype has been validated in laboratory experiments on prostate phantoms and in a clinical study. The results obtained on model systems and in vivo images from patients prove that PMI has potential to become a diagnostic tool that could largely supplant DRE through its higher sensitivity, quantitative record storage, ease-of-use and inherent low cost. PMID:17024836

  15. Characterization of impact damage in woven fiber composites using fiber Bragg grating sensing and NDE

    NASA Astrophysics Data System (ADS)

    Hiche, Cristobal; Liu, Kuang C.; Seaver, Mark; Wei, Jun; Chattopadhyay, Aditi

    2009-03-01

    Woven fiber composites are currently being investigated due to their advantages over other materials, making them suitable for low weight, high stiffness, and high interlaminar fracture toughness applications such as missiles, body armor, satellites, and many other aerospace applications. Damage characterization of woven fabrics is a complex task due to their tendency to exhibit different failure modes based on the weave configuration, orientation, ply stacking and other variables. A multiscale model is necessary to accurately predict progressive damage. The present research is an experimental study on damage characterization of three different woven fiber laminates under low energy impact using Fiber Bragg Grating (FBG) sensors and flash thermography. A correlation between the measured strain from FBG sensors and the damaged area obtained from flash thermography imaging has been developed. It was observed that the peak strain in the fabrics were strongly dependent on the weave geometry and decreased at different rates as damage area increased due to dissimilar failure modes. Experimental observations were validated with the development of a multiscale model. A FBG sensor placement model was developed which showed that FBG sensor location and orientation plays a key role in the sensing capabilities of strain on the samples.

  16. Composite manufacturing: Simulation of 3-D resin transfer molding

    NASA Astrophysics Data System (ADS)

    Tan, Cheng Ping

    1998-10-01

    A technique was developed for simulating the resin transfer molding (RTM) process. The major feature of the technique is a computational steering system that enables the user to make changes during the simulation. Specifically, at any instance, the user can inspect the progress of the resin front. On the basis of the observed resin front position, the user can, as needed, change the port and vent locations, open and close ports and vents, adjust the inlet and exit pressures or flow rates, and reorient the mold with respect to the gravitational field. Additionally, the user can "rewind" the simulator to any previous time in the mold filling process, make any of the above changes and then continue the simulation. The technique is augmented by a computer code which has three main components, the Simulator, the Graphics User Interface (GUI), and the Global Data Storage. The Simulator is a finite element code that calculates the resin flow inside the fiber preform. The GUI serves as the interface between the user and the Simulator; it provides the commands to the Simulator and displays the results. The Global Data Storage is the module that manages the exchange of data between the GUI and the Simulator. The computer code (designated as SUPERTMsb-3D) is suitable for simulating the resin flow inside two-dimensional as well as three-dimensional fiber preforms of arbitrary shapes. The use of this computer code is illustrated through sample problems. These problems demonstrate how (with this code) the designer can establish the port and vent locations, opening and closing sequences of ports and vents such that the fiber preform is filled completely in the shortest time with the fewest number of vents.

  17. EFFECTS OF HETEROGENEITY ON THE STRENGTH OF 3D COMPOSITES

    SciTech Connect

    M. MAHESH; I. BEYERLEIN; S. PHOENIX

    2001-02-01

    Monte Carlo simulation interpreted with theoretical modeling is used to study the statistical failure modes in unidirectional composites consisting of a hexagonal array of elastic fibers embedded in an elastic matrix. Composite structure is idealized using the chain-of-bundles model in terms of bundles of length {delta} arranged along the fiber direction. Fibers element strengths in {delta}-bundles are taken to be Weibull distributed and Hedgepeth and Van Dyke load sharing is assumed for transverse fiber break arrays. Simulations of {delta}-bundle failure reveal two regimes. When fiber strength variability is low, the dominant failure mode is by growing clusters of fiber breaks up to instability. When this variability is high, cluster formation is suppressed by a more dispersed fiber failure mode. Corresponding to these two cases, they construct simple models that predict the strength distribution of a {delta}-bundle. Their predictions compare very favorably with simulations in the two cases.

  18. An integrated computational materials engineering method for woven carbon fiber composites preforming process

    NASA Astrophysics Data System (ADS)

    Zhang, Weizhao; Ren, Huaqing; Wang, Zequn; Liu, Wing K.; Chen, Wei; Zeng, Danielle; Su, Xuming; Cao, Jian

    2016-10-01

    An integrated computational materials engineering method is proposed in this paper for analyzing the design and preforming process of woven carbon fiber composites. The goal is to reduce the cost and time needed for the mass production of structural composites. It integrates the simulation methods from the micro-scale to the macro-scale to capture the behavior of the composite material in the preforming process. In this way, the time consuming and high cost physical experiments and prototypes in the development of the manufacturing process can be circumvented. This method contains three parts: the micro-scale representative volume element (RVE) simulation to characterize the material; the metamodeling algorithm to generate the constitutive equations; and the macro-scale preforming simulation to predict the behavior of the composite material during forming. The results show the potential of this approach as a guidance to the design of composite materials and its manufacturing process.

  19. Thermo-elastic behavior of deformed woven fabric composites at elevated temperatures: Part 1

    SciTech Connect

    Vu-Khanh, T.; Liu, B.

    1994-12-31

    This paper presents the results of a study on the effects of temperature on the thermo-elastic properties of woven fabric composites. The thermo-mechanical behavior of woven fabric composites is characterized by a laminate composed of four fictional unidirectional plies, called the sub-plies model. The model allows determination of the thermo-elastic properties of deformed fabric composites (non-orthogonal structure) and direct use of layered shell elements in finite element codes. A special procedure is also proposed to measure the fiber undulation effect and to predict the on-axis thermo-elastic coefficients of the equivalent constituent plies. The thermo-elastic behavior at elevated temperature was investigated on graphite/epoxy fabric composites. Experimental measurements were carried out from 23 C to 177 C. The results revealed that the equivalent thermal expansion coefficients of the sub-plies remain almost constant over a wide range of temperature. However, the equivalent elastic moduli and Poison`s ratio of the sub-plies vary nonlinearly with temperature. Semiempirical equations based on the experimental data were also developed to predict the equivalent on-axis thermo-elastic properties of the fictional constituent plies in the sub-plies model as a function of temperature.

  20. CEMCAN Software Enhanced for Predicting the Properties of Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Mital, Subodh K.; DiCarlo, James A.

    2000-01-01

    Major advancements are needed in current high-temperature materials to meet the requirements of future space and aeropropulsion structural components. Ceramic matrix composites (CMC's) are one class of materials that are being evaluated as candidate materials for many high-temperature applications. Past efforts to improve the performance of CMC's focused primarily on improving the properties of the fiber, interfacial coatings, and matrix constituents as individual phases. Design and analysis tools must take into consideration the complex geometries, microstructures, and fabrication processes involved in these composites and must allow the composite properties to be tailored for optimum performance. Major accomplishments during the past year include the development and inclusion of woven CMC micromechanics methodology into the CEMCAN (Ceramic Matrix Composites Analyzer) computer code. The code enables one to calibrate a consistent set of constituent properties as a function of temperature with the aid of experimentally measured data.

  1. Development of generalized 3-D braiding machines for composite preforms

    NASA Astrophysics Data System (ADS)

    Huey, Cecil O., Jr.; Farley, Gary L.

    1992-10-01

    The development of prototype braiding machines for the production of generalized braid patterns is described. Mechanical operating principles and control strategies are presented for two prototype machines which have been fabricated and evaluated. Both machines represent advances over current fabrication techniques for composite materials by enabling nearly ideal control of fiber orientations within preform structures. They permit optimum design of parts that might be subjected to complex loads or that have complex forms. Further, they overcome both the lack of general control of produced fiber architectures and the complexity of other weaving processes that have been proposed for the same purpose. One prototype, the Farley braider, consists of an array of turntables that can be made to oscillate in 90 degree steps. Yarn ends are transported about the surface formed by the turntables by motorized tractors which are controlled through an optical link with the turntables and powered through electrical contact with the turntables. The necessary relative motions are produced by a series of linear tractor moves combined with a series of turntable rotations. As the tractors move about, they weave the yarn ends into the desired pattern. The second device, the shuttle plate braider, consists of a braiding surface formed by an array of stationary square sections, each separated from its neighbors by a gap. A plate beneath this surface is caused to reciprocate in two perpendicular directions, first in one direction and then in the other. This movement is made possibly by openings in the plate that clear short columns supporting the surface segments. Yarn ends are moved about the surface and interwoven by shuttles which engage the reciprocating plate as needed to yield the desired movements. Power and control signals are transmitted to the shuttles through electrical contact with the braiding surface. The shuttle plate is a passively driven prime mover that supplies the power

  2. Development of generalized 3-D braiding machines for composite preforms

    NASA Technical Reports Server (NTRS)

    Huey, Cecil O., Jr.; Farley, Gary L.

    1992-01-01

    The development of prototype braiding machines for the production of generalized braid patterns is described. Mechanical operating principles and control strategies are presented for two prototype machines which have been fabricated and evaluated. Both machines represent advances over current fabrication techniques for composite materials by enabling nearly ideal control of fiber orientations within preform structures. They permit optimum design of parts that might be subjected to complex loads or that have complex forms. Further, they overcome both the lack of general control of produced fiber architectures and the complexity of other weaving processes that have been proposed for the same purpose. One prototype, the Farley braider, consists of an array of turntables that can be made to oscillate in 90 degree steps. Yarn ends are transported about the surface formed by the turntables by motorized tractors which are controlled through an optical link with the turntables and powered through electrical contact with the turntables. The necessary relative motions are produced by a series of linear tractor moves combined with a series of turntable rotations. As the tractors move about, they weave the yarn ends into the desired pattern. The second device, the shuttle plate braider, consists of a braiding surface formed by an array of stationary square sections, each separated from its neighbors by a gap. A plate beneath this surface is caused to reciprocate in two perpendicular directions, first in one direction and then in the other. This movement is made possibly by openings in the plate that clear short columns supporting the surface segments. Yarn ends are moved about the surface and interwoven by shuttles which engage the reciprocating plate as needed to yield the desired movements. Power and control signals are transmitted to the shuttles through electrical contact with the braiding surface. The shuttle plate is a passively driven prime mover that supplies the power

  3. Modeling the Effect of Multiple Matrix Cracking Modes on Cyclic Hysteresis Loops of 2D Woven Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-08-01

    In this paper, the effect of multiple matrix cracking modes on cyclic loading/unloading hysteresis loops of 2D woven ceramic-matrix composites (CMCs) has been investigated. The interface slip between fibers and the matrix existed in matrix cracking mode 3 and mode 5, in which matrix cracking and interface debonding occurred in longitudinal yarns, are considered as the major reason for hysteresis loops of 2D woven CMCs. The effects of fiber volume content, peak stress, matrix crack spacing, interface properties, matrix cracking mode proportion and interface wear on interface slip and hysteresis loops have been analyzed. The cyclic loading/unloading hysteresis loops of 2D woven SiC/SiC composite corresponding to different peak stresses have been predicted using the present analysis. It was found that the damage parameter, i.e., the proportion of matrix cracking mode 3 in the entire cracking modes of the composite, increases with increasing peak stress.

  4. 3D thermography in non-destructive testing of composite structures

    NASA Astrophysics Data System (ADS)

    Hellstein, Piotr; Szwedo, Mariusz

    2016-12-01

    The combination of 3D scanners and infrared cameras has lead to the introduction of 3D thermography. Such analysis produces results in the form of three-dimensional thermograms, where the temperatures are mapped on a 3D model reconstruction of the inspected object. All work in the field of 3D thermography focused on its utility in passive thermography inspections. The authors propose a new real-time 3D temperature mapping method, which for the first time can be applied to active thermography analyses. All steps required to utilise 3D thermography are discussed, starting from acquisition of three-dimensional and infrared data, going through image processing and scene reconstruction, finishing with thermal projection and ray-tracing visualisation techniques. The application of the developed method was tested during diagnosis of several industrial composite structures—boats, planes and wind turbine blades.

  5. Transient Creep Behavior of a Plain Woven SiC Fiber/SiC Matrix Composite

    NASA Astrophysics Data System (ADS)

    Bessho, Takayuki; Ogasawara, Toshio; Aoki, Takuya; Ishikawa, Takashi; Ochi, Yasuo

    The present work investigates the transient creep behavior of a plain woven Tyranno™ Lox-M (Si-Ti-C-O) fiber/SiC matrix composite at 1473K in air. Tensile creep tests were carried out under a constant load between 80 and 160MPa. A creep strain rate is generally represented by ɛ∝ σn with a constant stress exponent, however the stress exponent decreased with time for this composite material. Monotonic tensile tests were also conducted for loading rates of 0.03, 0.3, and 3kN/min in order to investigate the effect of creep strain on tensile stress/strain behavior. Based on the empirical transient creep equation and creep-hardening model, stress/strain curves under monotonic tensile loading were predicted. A good correlation was obtained between the predicted and measured composite stress/strain curves using strain-hardening model.

  6. Vibration reduction of a woven composite fan blade by piezoelectric shunted devices

    NASA Astrophysics Data System (ADS)

    Thierry, Olivier; De Smet, Olivier; Deü, Jean-François

    2016-09-01

    This study concerns the vibration reduction in the low frequency range of a composite fan blade of a turbojet engine with piezoelectric devices. The interest is to increase lifespan and avoid flutter phenomena by reducing the vibration amplitude. The solution considered in the work consists in using piezoelectric elements connected to a passive electric circuit usually called shunt. The use of woven composite materials for fan blades enables to plan on embedding piezoelectric materials, for instance in the form of patches inserted between the composite and the coating material. The work presented during this conference will illustrate the feasibility of a piezoelectric shunted device integrated in an industrial application that doesn't require electrical supply. For such a structure, it is shown that a purely passive resonant shunt can significantly reduce the level of vibration of the second bending mode and that a good correlation between experiments and simulations validates the best fitting finite element model.

  7. Analysis of mechanical properties anisotropy of nanomodified carbon fibre-reinforced woven composites

    NASA Astrophysics Data System (ADS)

    Ruslantsev, A. N.; Portnova, Ya M.; Tairova, L. P.; Dumansky, A. M.

    2016-10-01

    The polymer binder cracking problem arises while designing and maintaining polymer composite-based aircraft load-bearing members. Some technological methods are used to solve this problem. In particular the injection of nanoagents can block the initiation and growth of microscopic cracks. Crack propagation can also be blocked if the strain energy release is not related with fracturing. One of the possible ways for such energy release is creep. Testing of the anisotropy of the woven carbon fibre reinforced plastic elastic characteristics and creep have been conducted. The samples with different layouts have been made of woven carbon fibre laminate BMI-3/3692 with nanomodified bismaleimide matrix. This matrix has a higher glass transition temperature and improved mechanical properties. The deformation regularities have been analyzed, layer elastic characteristics have been determined. The constitutive equations describing composite material creep have been obtained and its parameters have been defined. Experimental and calculated creep curves have been plotted. It was found that the effects of rheology arise as the direction of load does not match the direction of reinforcing fibres of the material.

  8. Experimental determination of Representative Volume Element (RVE) size in woven composites

    NASA Astrophysics Data System (ADS)

    Koohbor, Behrad; Ravindran, Suraj; Kidane, Addis

    2017-03-01

    A systematic approach is proposed to estimate the length scales of the representative volume element (RVE) in orthogonal plain woven composites. The approach is based on experimental full-field deformation measurements at mesoscopic scales. Stereovision digital image correlation (DIC) is conducted to determine the full-field strain distribution in on- and off-axis specimens loaded axially in tension. A sensitivity analysis is carried out to optimize the image correlation parameters. Using the optimized set of image correlation parameters, full-field strains are measured and used in conjunction with a simple strain averaging algorithm to identify the length scales at which globally applied and spatially-averaged local strains converge in values. The size of a virtual window containing local strain data, the average of which has the same value as the global strain, is identified as the RVE dimensions for the examined material. The smallest RVE sizes found in this work are shown to be both strain and angle dependent. The largest RVE dimension obtained is reported as a unique, strain and orientation insensitive RVE size for the woven composite examined.

  9. Passive and active thermography for in situ damage monitoring in woven composites during mechanical testing

    NASA Astrophysics Data System (ADS)

    Roche, J.-M.; Balageas, D.; Lamboul, B.; Bai, G.; Passilly, F.; Mavel, A.; Grail, G.

    2013-01-01

    The aim of the present paper is to highlight the contribution of both passive and active infrared thermography for in situ damage detection and monitoring in a 2D woven composite, during a mechanical testing constituted of multiple sequences of loadings and intermediate pauses. During the monotonic tensile loadings, damages such as matrix cracking and fiber-matrix debondings are monitored by passive thermography. Their thermal signatures are analyzed and the released heat, which is assumed to be a relevant index of their severity, is evaluated and correlated to the associated acoustic energies, simultaneously recorded. Finally, the contribution of the TSR (Thermographic Signal Reconstruction) advanced processing technique to provide a qualitative overview of the detected damages is underlined. As for the constant stress plateau levels, a nondestructive damage inspection of the tested specimen is carried out by pulsed thermography. The difficulties, due to the woven structure of the composite, in detecting any damage are put into relief. Once more, it is shown that the TSR technique can be useful.

  10. Forming simulation of woven composite fibers and its influence on structural performance

    NASA Astrophysics Data System (ADS)

    Divine, Vincent; Beauchesne, Erwan; Roy, Subir; Palaniswamy, Hariharasudhan

    2013-12-01

    In recent years, the interest in composite material as a replacement for metals has been growing. The automotive industry, in its constant quest for weight reduction, is now seriously considering composite materials as a substitute for sheet metal components to meet future fuel consumption standards. However, composite forming processes are expensive and difficult to control because of its complex composition with fiber and matrix layers or plies and its dependency on many parameters, such as non-linearity of tensile stiffness, effect of shear rate, temperature and friction. Hence, numerical simulation could be a viable approach to predict material behavior during composite forming. The objective of this study is to highlight capabilities of RADIOSS®, a non-linear finite element analysis based structural solver commonly used for stamping and crash analyses, to simulate forming simulation of composite plies made from woven fibers. For validation the well-known double dome model is used with material data published in NUMISHEET'05 proceedings. It is modeled as a woven fabric with an elastic anisotropic fabric material law available in RADIOSS. This material law is able to consider properties along the two directions of anisotropy, warp and weft. The compared result is the shear angle after stamping that is, the variation of angle between warp and weft fibers, at several prescribed points on the ply. The variation of this angle has a strong impact on material characteristics which severely deteriorates when a critical value is reached. Hence, a study on crash simulations is performed, after mapping fibers angles from stamping simulation.

  11. Investigation of out of plane compressive strength of 3D printed sandwich composites

    NASA Astrophysics Data System (ADS)

    Dikshit, V.; Yap, Y. L.; Goh, G. D.; Yang, H.; Lim, J. C.; Qi, X.; Yeong, W. Y.; Wei, J.

    2016-07-01

    In this study, the 3D printing technique was utilized to manufacture the sandwich composites. Composite filament fabrication based 3D printer was used to print the face-sheet, and inkjet 3D printer was used to print the sandwich core structure. This work aims to study the compressive failure of the sandwich structure manufactured by using these two manufacturing techniques. Two different types of core structures were investigated with the same type of face-sheet configuration. The core structures were printed using photopolymer, while the face-sheet was made using nylon/glass. The out-of-plane compressive strength of the 3D printed sandwich composite structure has been examined in accordance with ASTM standards C365/C365-M and presented in this paper.

  12. Fused filament 3D printing of ionic polymer-metal composites (IPMCs)

    NASA Astrophysics Data System (ADS)

    Carrico, James D.; Traeden, Nicklaus W.; Aureli, Matteo; Leang, Kam K.

    2015-12-01

    This paper describes a new three-dimensional (3D) fused filament additive manufacturing (AM) technique in which electroactive polymer filament material is used to build soft active 3D structures, layer by layer. Specifically, the unique actuation and sensing properties of ionic polymer-metal composites (IPMCs) are exploited in 3D printing to create electroactive polymer structures for application in soft robotics and bio-inspired systems. The process begins with extruding a precursor material (non-acid Nafion precursor resin) into a thermoplastic filament for 3D printing. The filament is then used by a custom-designed 3D printer to manufacture the desired soft polymer structures, layer by layer. Since at this stage the 3D-printed samples are not yet electroactive, a chemical functionalization process follows, consisting in hydrolyzing the precursor samples in an aqueous solution of potassium hydroxide and dimethyl sulfoxide. Upon functionalization, metal electrodes are applied on the samples through an electroless plating process, which enables the 3D-printed IPMC structures to be controlled by voltage signals for actuation (or to act as sensors). This innovative AM process is described in detail and the performance of 3D printed IPMC actuators is compared to an IPMC actuator fabricated from commercially available Nafion sheet material. The experimental results show comparable performance between the two types of actuators, demonstrating the potential and feasibility of creating functional 3D-printed IPMCs.

  13. Experimental Investigation About Stamping Behaviour of 3D Warp Interlock Composite Preforms

    NASA Astrophysics Data System (ADS)

    Dufour, Clément; Wang, Peng; Boussu, François; Soulat, Damien

    2014-10-01

    Forming of continuous fibre reinforcements and thermoplastic resin commingled prepregs can be performed at room temperature due to its similar textile structure. The "cool" forming stage is better controlled and more economical. The increase of temperature and the resin consolidation phases after the forming can be carried out under the isothermal condition thanks to a closed system. It can avoid the manufacturing defects easily experienced in the non-isothermal thermoforming, in particular the wrinkling [1]. Glass/Polypropylene commingled yarns have been woven inside different three-dimensional (3D) warp interlock fabrics and then formed using a double-curved shape stamping tool. The present study investigates the in-plane and through-thickness behaviour of the 3D warp interlock fibrous reinforcements during forming with a hemispherical punch. Experimental data allow analysing the forming behaviour in the warp and weft directions and on the influence of warp interlock architectures. The results point out that the layer to layer warp interlock preform has a better stamping behaviour, in particular no forming defects and good homogeneity in thickness.

  14. Three-dimensional microstructural design of woven fabric composite material by homogenization method

    SciTech Connect

    Takano, Naoki; Zako, Masaru

    1995-11-01

    The strength of woven fabric composite materials depends on the microstructural geometry. However, the conventional methods for mechanical analysis, which have been widely used so far, are insufficient because they cannot take into account for the three-dimensional microstructure. In this study, three-dimensional homogenization method is shown to be effective for the evaluations of the material constants, microscopic stresses and the strength. It has been found that the transverse stresses in the direction of lamination play an important role for the fracture of both fiber bundle and resin. Also, the effect of the mismatched lay-up on the strength has been investigated. It has well been predicted that the mismatched lay-up causes the reduction of the strength and the difference of crack initiation in the resin. These simulations give a new concept of the microstructural design of the composite materials.

  15. Multi-Scale Modeling of an Integrated 3D Braided Composite with Applications to Helicopter Arm

    NASA Astrophysics Data System (ADS)

    Zhang, Diantang; Chen, Li; Sun, Ying; Zhang, Yifan; Qian, Kun

    2017-01-01

    A study is conducted with the aim of developing multi-scale analytical method for designing the composite helicopter arm with three-dimensional (3D) five-directional braided structure. Based on the analysis of 3D braided microstructure, the multi-scale finite element modeling is developed. Finite element analysis on the load capacity of 3D five-directional braided composites helicopter arm is carried out using the software ABAQUS/Standard. The influences of the braiding angle and loading condition on the stress and strain distribution of the helicopter arm are simulated. The results show that the proposed multi-scale method is capable of accurately predicting the mechanical properties of 3D braided composites, validated by the comparison the stress-strain curves of meso-scale RVCs. Furthermore, it is found that the braiding angle is an important factor affecting the mechanical properties of 3D five-directional braided composite helicopter arm. Based on the optimized structure parameters, the nearly net-shaped composite helicopter arm is fabricated using a novel resin transfer mould (RTM) process.

  16. Mechanical properties of 2D and 3D braided textile composites

    NASA Technical Reports Server (NTRS)

    Norman, Timothy L.

    1991-01-01

    The purpose of this research was to determine the mechanical properties of 2D and 3D braided textile composite materials. Specifically, those designed for tension or shear loading were tested under static loading to failure to investigate the effects of braiding. The overall goal of the work was to provide a structural designer with an idea of how textile composites perform under typical loading conditions. From test results for unnotched tension, it was determined that the 2D is stronger, stiffer, and has higher elongation to failure than the 3D. It was also found that the polyetherether ketone (PEEK) resin system was stronger, stiffer, and had higher elongation at failure than the resin transfer molding (RTM) epoxy. Open hole tension tests showed that PEEK resin is more notch sensitive than RTM epoxy. Of greater significance, it was found that the 3D is less notch sensitive than the 2D. Unnotched compression tests indicated, as did the tension tests, that the 2D is stronger, stiffer, and has higher elongation at failure than the RTM epoxy. The most encouraging results were from compression after impact. The 3D braided composite showed a compression after impact failure stress equal to 92 percent of the unimpacted specimen. The 2D braided composite failed at about 67 percent of the unimpacted specimen. Higher damage tolerance is observed in textiles over conventional composite materials. This is observed in the results, especially in the 3D braided materials.

  17. Effect of Ductile Agents on the Dynamic Behavior of SiC3D Network Composites

    NASA Astrophysics Data System (ADS)

    Zhu, Jingbo; Wang, Yangwei; Wang, Fuchi; Fan, Qunbo

    2016-10-01

    Co-continuous SiC ceramic composites using pure aluminum, epoxy, and polyurethane (PU) as ductile agents were developed. The dynamic mechanical behavior and failure mechanisms were investigated experimentally using the split Hopkinson pressure bar (SHPB) method and computationally by finite element (FE) simulations. The results show that the SiC3D/Al composite has the best overall performance in comparison with SiC3D/epoxy and SiC3D/PU composites. FE simulations are generally consistent with experimental data. These simulations provide valuable help in predicting mechanical strength and in interpreting the experimental results and failure mechanisms. They may be combined with micrographs for fracture characterizations of the composites. We found that interactions between the SiC phase and ductile agents under dynamic compression in the SHPB method are complex, and that interfacial condition is an important parameter that determines the mechanical response of SiC3D composites with a characteristic interlocking structure during dynamic compression. However, the effect of the mechanical properties of ductile agents on dynamic behavior of the composites is a second consideration in the production of the composites.

  18. 3D flexible NiTi-braided elastomer composites for smart structure applications

    NASA Astrophysics Data System (ADS)

    Heller, L.; Vokoun, D.; Šittner, P.; Finckh, H.

    2012-04-01

    While outstanding functional properties of thin NiTi wires are nowadays well recognized and beneficially utilized in medical NiTi devices, development of 2D/3D wire structures made out of these NiTi wires remains challenging and mostly unexplored. The research is driven by the idea of creating novel 2D/3D smart structures which inherit the functional properties of NiTi wires and actively utilize geometrical deformations within the structure to create new/improved functional properties. Generally, textile technology provides attractive processing methods for manufacturing 2D/3D smart structures made out of NiTi wires. Such structures may be beneficially combined with soft elastomers to create smart deformable composites. Following this route, we carried out experimental work focused on development of 3D flexible NiTi-braided elastomer composites involving their design, laboratory manufacture and thermomechanical testing. We describe the manufacturing technology and structural properties of these composites; and perform thermomechanical tests on the composites, focusing particularly on quasistatic tensile properties, energy absorption, damping and actuation under tensile loading. Functional thermomechanical properties of the composites are discussed with regard to the mechanical properties of the components and architecture of the composites. It is found that the composites indeed inherit all important features of the thermomechanical behavior of NiTi wires but, due to their internal architecture, outperform single NiTi wires in some features such as the magnitude of recoverable strain, superelastic damping capacity and thermally induced actuation strain.

  19. Fatigue Hysteresis Behavior of 2.5D Woven C/SiC Composites: Theory and Experiments

    NASA Astrophysics Data System (ADS)

    Hu, Xuteng; Sun, Zhigang; Yang, Fushu; Chen, Xihui; Song, Yingdong

    2017-02-01

    This paper presents an intriguing fatigue hysteresis behavior of 2.5 dimensional woven C/SiC composites via the integration tool of advanced experimental techniques with a multiscale theoretical model. Tension-tension fatigue experiment has been carried out to predict the fatigue hysteresis properties of 2.5D woven C/SiC composite at room temperature, accompanied with the fracture of specimens to investigate the mechanism of fatigue damage. Meanwhile, a multiscale fatigue model of 2.5D woven C/SiC composites, which encompasses a micro-scale model of fiber/matrix/porosity in fiber tows and a macro-scale model of unit-cell, has been proposed to provide a reliable validation of the experimental results based on fiber damages resulting from relative slip motion with respect to matrix at interfaces and the architecture of 2.5D woven C/SiC composites. The predicted hysteresis loop from theoretical model at room temperature holds great agreement with that from tension-tension fatigue experiments. Also, effects of fatigue load, braided structural parameters and material properties at micro scale on fatigue hysteresis behavior have been investigated.

  20. Creep-Rupture Behavior of a Woven Ceramic Matrix Composite at Elevated Temperatures in a Humid Environment

    DTIC Science & Technology

    2006-03-01

    284-291 (1999) 4. LaRochelle, K. J . Tensile Stress Rupture Behavior of a Woven Ceramic Matrix Composite in Humid Environments at Intermediate...Composites,” Journal of the. American Ceramic. Society, 78 [8]: 2097-100 (1995). 13. Musil , S.S. Characterization of Creep Behavior of Oxide/Oxide...1989). 17. Filipuzzi, L., G. Camus, R. Naslain, and J . Thebault. “ Oxidation Mechanisms and Kinetics of 1D-SiC/C/SiC Composite Materials: I, An

  1. Dynamic mechanical analysis and high strain-rate energy absorption characteristics of vertically aligned carbon nanotube reinforced woven fiber-glass composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The dynamic mechanical behavior and energy absorption characteristics of nano-enhanced functionally graded composites, consisting of 3 layers of vertically aligned carbon nanotube (VACNT) forests grown on woven fiber-glass (FG) layer and embedded within 10 layers of woven FG, with polyester (PE) and...

  2. RVE Model with Porosity for 2D Woven CVI SiCf/SiC Composites

    NASA Astrophysics Data System (ADS)

    Shen, Xiuli; Gong, Longdong

    2016-12-01

    A representative volume element (RVE) model with porosity for 2D woven chemical vapor infiltration (CVI) SiCf/SiC composites is presented, and its mechanical properties are analyzed. Samples are divided after a tensile test, and their cross sections are scanned with a scanning electron microscope. The size of the feature structure of the RVE model is determined based on the measurement statistics of the feature structure parameters. In accordance with CVI technology, the deposition rates of the matrix in each direction along the surface of fiber bundles are assumed to be similar. The porosity structure is formed naturally when the RVE model is established. The RVE model conforms to the real structure and accurately shows the location and geometric shape of internal porosity. The relative error of the tensile modulus value estimated from the RVE model through the asymptotic expansion homogenization method and experimental data is 3.26%. Therefore, the RVE model is accurate and efficient.

  3. Hybrid composite laminates reinforced with Kevlar/carbon/glass woven fabrics for ballistic impact testing.

    PubMed

    Randjbaran, Elias; Zahari, Rizal; Jalil, Nawal Aswan Abdul; Majid, Dayang Laila Abang Abdul

    2014-01-01

    Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers.

  4. The elastic and inelastic behavior of woven graphite fabric reinforced polyimide composites

    NASA Astrophysics Data System (ADS)

    Searles, Kevin H.

    In many aerospace and conventional engineering applications, load-bearing composite structures are designed with the intent of being subjected to uniaxial stresses that are predominantly tensile or compressive. However, it is likely that biaxial and possibly triaxial states of stress will exist throughout the in-service life of the structure or component. The existing paradigm suggests that unidirectional tape materials are superior under uniaxial conditions since the vast majority of fibers lie in-plane and can be aligned to the loading axis. This may be true, but not without detriment to impact performance, interlaminar strength, strain to failure and complexity of part geometry. In circumstances where a sufficient balance of these properties is required, composites based on woven fabric reinforcements become attractive choices. In this thesis, the micro- and mesoscale elastic behavior of composites based on 8HS woven graphite fabric architectures and polyimide matrices is studied analytically and numerically. An analytical model is proposed to predict the composite elastic constants and is verified using numerical strain energy methods of equivalence. The model shows good agreement with the experiments and numerical strain energy equivalence. Lamina stresses generated numerically from in-plane shear loading show substantial shear and transverse normal stress concentrations in the transverse undulated tow which potentially leads to intralaminar damage. The macroscale inelastic behavior of the same composites is also studied experimentally and numerically. On an experimental basis, the biaxial and modified biaxial Iosipescu test methods are employed to study the weaker-mode shear and biaxial failure properties at room and elevated temperatures. On a numerical basis, the macroscale inelastic shear behavior of the composites is studied. Structural nonlinearities and material nonlinearities are identified and resolved. In terms of specimen-to-fixture interactions

  5. Characterization of the as Manufactured Variability in a CVI SiC/SiC Woven Composite

    NASA Technical Reports Server (NTRS)

    Bonacuse, Peter J.; Mital, Subodh; Goldberg, Robert

    2011-01-01

    The microstructure of a 2D woven ceramic matrix composite displays significant variability and irregularity. For example, a chemical vapor infiltrated (CVI) SiC/SiC composite exhibits significant amount of porosity arranged in irregular patterns. Furthermore, the fiber tows within a ply frequently have irregular shape and spacing, and the stacked plies are often misaligned and irregularly nested within each other. The goal of an ongoing project at NASA Glenn is to investigate the effects of the complex microstructure and its variability on the properties and the durability of the material. One key requirement for this effort is the development of methods to characterize the distribution in as-fabricated ceramic matrix composite (CMC) microstructures with the objective of correlating microstructural distribution parameters with mechanical performance. An initial task in this effort was to perform quantitative image analysis of polished cross sections of CVI SiC/SiC composite specimens. This analysis provided sample distributions of various microstructural composite features, including: inter-tow pore sizes and shapes, transverse sectioned tow sizes and shapes, and within ply tow spacing. This information can then be used to quantify the effect of extreme values of these features on the local stress state with the goal of determining the likelihood of matrix cracking at a given external load.

  6. The Electrical and Thermal Conductivity of Woven Pristine and Intercalated Graphite Fiber-Polymer Composites

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Vandenburg, Yvonne Yoder; Berkebile, Steven; Stueben, Heather; Balagadde, Frederick

    2002-01-01

    A series of woven fabric laminar composite plates and narrow strips were fabricated from a variety of pitch-based pristine and bromine intercalated graphite fibers in an attempt to determine the influence of the weave on the electrical and thermal conduction. It was found generally that these materials can be treated as if they are homogeneous plates. The rule of mixtures describes the resistivity of the composite fairly well if it is realized that only the component of the fibers normal to the equipotential surface will conduct current. When the composite is narrow with respect to the fiber weave, however, there is a marked angular dependence of the resistance which was well modeled by assuming that the current follows only along the fibers (and not across them in a transverse direction), and that the contact resistance among the fibers in the composite is negligible. The thermal conductivity of composites made from less conductive fibers more closely followed the rule of mixtures than that of the high conductivity fibers, though this is thought to be an artifact of the measurement technique. Electrical and thermal anisotropy could be induced in a particular region of the structure by weaving together high and low conductivity fibers in different directions, though this must be done throughout all of the layers of the structure as interlaminar conduction precludes having only the top layer carry the anisotropy. The anisotropy in the thermal conductivity is considerably less than either that predicted by the rule of mixtures or the electrical resistivity.

  7. Formation and properties of 3D metamaterial composites fabricated using nanometer scale laser lithography (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Prokes, Sharka M.; Perkins, Frank K.; Glembocki, Orest J.

    2015-08-01

    Metamaterials designed for the visible or near IR wavelengths require patterning on the nanometer scale. To achieve this, e-beam lithography is used, but it is extremely difficult and can only produce 2D structures. A new alternative technique to produce 2D and 3D structures involves laser fabrication using the Nanoscribe 3D laser lithography system. This is a direct laser writing technique which can form arbitrary 3D nanostructures on the nanometer scale and is based on multi-photon polymerization. We are creating 2D and 3D metamaterials via this technique, and subsequently conformally coating them using Atomic Layer Deposition of oxides and Ag. We will discuss the optical properties of these novel composite structures and their potential for dual resonant metamaterials.

  8. Advanced resin systems and 3D textile preforms for low cost composite structures

    NASA Technical Reports Server (NTRS)

    Shukla, J. G.; Bayha, T. D.

    1993-01-01

    Advanced resin systems and 3D textile preforms are being evaluated at Lockheed Aeronautical Systems Company (LASC) under NASA's Advanced Composites Technology (ACT) Program. This work is aimed towards the development of low-cost, damage-tolerant composite fuselage structures. Resin systems for resin transfer molding and powder epoxy towpreg materials are being evaluated for processability, performance and cost. Three developmental epoxy resin systems for resin transfer molding (RTM) and three resin systems for powder towpregging are being investigated. Various 3D textile preform architectures using advanced weaving and braiding processes are also being evaluated. Trials are being conducted with powdered towpreg, in 2D weaving and 3D braiding processes for their textile processability and their potential for fabrication in 'net shape' fuselage structures. The progress in advanced resin screening and textile preform development is reviewed here.

  9. Advanced Woven SiC/SiC Composites for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.

    2007-01-01

    The temperature, stress, and environmental conditions of many gas turbine, hypersonic, and even nuclear applications make the use of woven SiC/SiC composites an attractive enabling material system. The development in SiC/SiC composites over the past few years has resulted in significant advances in high temperature performance so that now these materials are being pursued for several turbine airfoil and reusable hypersonic applications. The keys to maximizing stress capability and maximizing temperature capability will be outlined for SiC/SiC. These include the type of SiC fiber, the fiber-architecture, and the matrix processing approach which leads to a variety of matrix compositions and structure. It will also be shown that a range of mechanical, thermal, and permeability properties can be attained and tailored depending on the needs of an application. Finally, some of the remaining challenges will be discussed in order for the use of these composite systems to be fully realized.

  10. 3D Printed Polycaprolactone Carbon Nanotube Composite Scaffolds for Cardiac Tissue Engineering.

    PubMed

    Ho, Chee Meng Benjamin; Mishra, Abhinay; Lin, Pearlyn Teo Pei; Ng, Sum Huan; Yeong, Wai Yee; Kim, Young-Jin; Yoon, Yong-Jin

    2017-04-01

    Fabrication of tissue engineering scaffolds with the use of novel 3D printing has gained lot of attention, however systematic investigation of biomaterials for 3D printing have not been widely explored. In this report, well-defined structures of polycaprolactone (PCL) and PCL- carbon nanotube (PCL-CNT) composite scaffolds have been designed and fabricated using a 3D printer. Conditions for 3D printing has been optimized while the effects of varying CNT percentages with PCL matrix on the thermal, mechanical and biological properties of the printed scaffolds are studied. Raman spectroscopy is used to characterise the functionalized CNTs and its interactions with PCL matrix. Mechanical properties of the composites are characterised using nanoindentation. Maximum peak load, elastic modulus and hardness increases with increasing CNT content. Differential scanning calorimetry (DSC) studies reveal the thermal and crystalline behaviour of PCL and its CNT composites. Biodegradation studies are performed in Pseudomonas Lipase enzymatic media, showing its specificity and effect on degradation rate. Cell imaging and viability studies of H9c2 cells from rat origin on the scaffolds are performed using fluorescence imaging and MTT assay, respectively. PCL and its CNT composites are able to show cell proliferation and have the potential to be used in cardiac tissue engineering.

  11. A Shell/3D Modeling Technique for the Analysis of Delaminated Composite Laminates

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; OBrien, T. Kevin

    2000-01-01

    A shell/3D modeling technique was developed for which a local solid finite element model is used only in the immediate vicinity of the delamination front. The goal was to combine the accuracy of the full three-dimensional solution with the computational efficiency of a shell finite element model. Multi-point constraints provided a kinematically compatible interface between the local 3D model and the global structural model which has been meshed with shell finite elements. Double Cantilever Beam, End Notched Flexure, and Single Leg Bending specimens were analyzed first using full 3D finite element models to obtain reference solutions. Mixed mode strain energy release rate distributions were computed using the virtual crack closure technique. The analyses were repeated using the shell/3D technique to study the feasibility for pure mode I, mode II and mixed mode I/II cases. Specimens with a unidirectional layup and with a multidirectional layup were simulated. For a local 3D model, extending to a minimum of about three specimen thicknesses on either side of the delamination front, the results were in good agreement with mixed mode strain energy release rates obtained from computations where the entire specimen had been modeled with solid elements. For large built-up composite structures the shell/3D modeling technique offers a great potential for reducing the model size, since only a relatively small section in the vicinity of the delamination front needs to be modeled with solid elements.

  12. A Simple, Low-Cost Conductive Composite Material for 3D Printing of Electronic Sensors

    PubMed Central

    Leigh, Simon J.; Bradley, Robert J.; Purssell, Christopher P.; Billson, Duncan R.; Hutchins, David A.

    2012-01-01

    3D printing technology can produce complex objects directly from computer aided digital designs. The technology has traditionally been used by large companies to produce fit and form concept prototypes (‘rapid prototyping’) before production. In recent years however there has been a move to adopt the technology as full-scale manufacturing solution. The advent of low-cost, desktop 3D printers such as the RepRap and Fab@Home has meant a wider user base are now able to have access to desktop manufacturing platforms enabling them to produce highly customised products for personal use and sale. This uptake in usage has been coupled with a demand for printing technology and materials able to print functional elements such as electronic sensors. Here we present formulation of a simple conductive thermoplastic composite we term ‘carbomorph’ and demonstrate how it can be used in an unmodified low-cost 3D printer to print electronic sensors able to sense mechanical flexing and capacitance changes. We show how this capability can be used to produce custom sensing devices and user interface devices along with printed objects with embedded sensing capability. This advance in low-cost 3D printing with offer a new paradigm in the 3D printing field with printed sensors and electronics embedded inside 3D printed objects in a single build process without requiring complex or expensive materials incorporating additives such as carbon nanotubes. PMID:23185319

  13. A simple, low-cost conductive composite material for 3D printing of electronic sensors.

    PubMed

    Leigh, Simon J; Bradley, Robert J; Purssell, Christopher P; Billson, Duncan R; Hutchins, David A

    2012-01-01

    3D printing technology can produce complex objects directly from computer aided digital designs. The technology has traditionally been used by large companies to produce fit and form concept prototypes ('rapid prototyping') before production. In recent years however there has been a move to adopt the technology as full-scale manufacturing solution. The advent of low-cost, desktop 3D printers such as the RepRap and Fab@Home has meant a wider user base are now able to have access to desktop manufacturing platforms enabling them to produce highly customised products for personal use and sale. This uptake in usage has been coupled with a demand for printing technology and materials able to print functional elements such as electronic sensors. Here we present formulation of a simple conductive thermoplastic composite we term 'carbomorph' and demonstrate how it can be used in an unmodified low-cost 3D printer to print electronic sensors able to sense mechanical flexing and capacitance changes. We show how this capability can be used to produce custom sensing devices and user interface devices along with printed objects with embedded sensing capability. This advance in low-cost 3D printing with offer a new paradigm in the 3D printing field with printed sensors and electronics embedded inside 3D printed objects in a single build process without requiring complex or expensive materials incorporating additives such as carbon nanotubes.

  14. MODELING THE TRANSVERSE THERMAL CONDUCTIVITY OF 2-D SICF/SIC COMPOSITES MADE WITH WOVEN FABRIC

    SciTech Connect

    Youngblood, Gerald E; Senor, David J; Jones, Russell H

    2004-06-01

    The hierarchical two-layer (H2L) model describes the effective transverse thermal conductivity (Keff) of a 2D-SiCf/SiC composite plate made from stacked and infiltrated woven fabric layers in terms of constituent properties and microstructural and architectural variables. The H2L model includes the effects of fiber-matrix interfacial conductance, high fiber packing fractions within individual tows and the non-uniform nature of 2D fabric/matrix layers that usually include a significant amount of interlayer porosity. Previously, H2L model Keff-predictions were compared to measured values for two versions of 2D Hi-Nicalon/PyC/ICVI-SiC composite, one with a “thin” (0.11m) and the other with a “thick” (1.04m) pyrocarbon (PyC) fiber coating, and for a 2D Tyranno SA/”thin” PyC/FCVI-SIC composite. In this study, H2L model Keff-predictions were compared to measured values for a 2D-SiCf/SiC composite made using the ICVI-process with Hi-Nicalon type S fabric and a “thin” PyC fiber coating. The values of Keff determined for the latter composite were significantly greater than the Keff-values determined for the composites made with either the Hi-Nicalon or the Tyranno SA fabrics. Differences in Keff-values were expected for the different fiber types, but major differences also were due to observed microstructural and architectural variations between the composite systems, and as predicted by the H2L model.

  15. Fatigue Damage in CFRP Woven Fabric Composites through Dynamic Modulus Measurements

    SciTech Connect

    Chiaki Miyasaka; K. L. Telschow

    2004-07-01

    Advanced fiber reinforced composite materials offer substantial advantages over metallic materials for the structural applications subjected to fatigue loading. With the increasing use of these composites, it is required to understand their mechanical response to cyclic loading (1)-(4). Our major concern in this work is to macroscopically evaluate the damage development in composites during fatigue loading. For this purpose, we examine what effect the fatigue damage may have on the material properties and how they can be related mathematically to each other. In general, as the damage initiates in composite materials and grows during cyclic loading, material properties such as modulus, residual strength and strain would vary and, in many cases, they may be significantly reduced because of the progressive accumulation of cracks. Therefore, the damage can be characterized by the change in material properties, which is expected to be available for non-destructive evaluation of the fatigue damage development in composites. Here, the tension-tension fatigue tests are firstly conducted on the plain woven fabric carbon fiber composites for different loading levels. In the fatigue tests, the dynamic elastic moduli are measured on real-time, which will decrease with an increasing number of cycles due to the degradation of stiffness. Then, the damage function presenting the damage development during fatigue loading is determined from the dynamic elastic moduli thus obtained, from which the damage function is formulated in terms of a number of cycles and an applied loading level. Finally, the damage function is shown to be applied for predicting the remaining lifetime of the CFRP composites subjected to two-stress level fatigue loading.

  16. 3D scaffold alters cellular response to graphene in a polymer composite for orthopedic applications.

    PubMed

    Kumar, Sachin; Azam, Dilkash; Raj, Shammy; Kolanthai, Elayaraja; Vasu, K S; Sood, A K; Chatterjee, Kaushik

    2016-05-01

    Graphene-based polymer nanocomposites are being studied for biomedical applications. Polymer nanocomposites can be processed differently to generate planar two-dimensional (2D) substrates and porous three-dimensional (3D) scaffolds. The objective of this work was to investigate potential differences in biological response to graphene in polymer composites in the form of 2D substrates and 3D scaffolds. Polycaprolactone (PCL) nanocomposites were prepared by incorporating 1% of graphene oxide (GO) and reduced graphene oxide (RGO). GO increased modulus and strength of PCL by 44 and 22% respectively, whereas RGO increased modulus and strength by 22 and 16%, respectively. RGO increased the water contact angle of PCL from 81° to 87° whereas GO decreased it to 77°. In 2D, osteoblast proliferated 15% more on GO composites than on PCL whereas RGO composite showed 17% decrease in cell proliferation, which may be attributed to differences in water wettability. In 3D, initial cell proliferation was markedly retarded in both GO (36% lower) and RGO (55% lower) composites owing to increased roughness due to the presence of the protruding nanoparticles. Cells organized into aggregates in 3D in contrast to spread and randomly distributed cells on 2D discs due to the macro-porous architecture of the scaffolds. Increased cell-cell contact and altered cellular morphology led to significantly higher mineralization in 3D. This study demonstrates that the cellular response to nanoparticles in composites can change markedly by varying the processing route and has implications for designing orthopedic implants such as resorbable fracture fixation devices and tissue scaffolds using such nanocomposites.

  17. Investigation of Effects of Material Architecture on the Elastic Response of a Woven Ceramic Matrix Composite

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Bonacuse, Peter J.; Mital, Subodh K.

    2012-01-01

    To develop methods for quantifying the effects of the microstructural variations of woven ceramic matrix composites on the effective properties and response of the material, a research program has been undertaken which is described in this paper. In order to characterize and quantify the variations in the microstructure of a five harness satin weave, CVI SiC/SiC, composite material, specimens were serially sectioned and polished to capture images that detailed the fiber tows, matrix, and porosity. Open source quantitative image analysis tools were then used to isolate the constituents and collect relevant statistics such as within ply tow spacing. This information was then used to build two dimensional finite element models that approximated the observed section geometry. With the aid of geometrical models generated by the microstructural characterization process, finite element models were generated and analyses were performed to quantify the effects of the microstructure and its variation on the effective stiffness and areas of stress concentration of the material. The results indicated that the geometry and distribution of the porosity appear to have significant effects on the through-thickness modulus. Similarly, stress concentrations on the outer surface of the composite appear to correlate to regions where the transverse tows are separated by a critical amount.

  18. Tension and compression fatigue response of unnotched 3D braided composites

    NASA Technical Reports Server (NTRS)

    Portanova, M. A.

    1992-01-01

    The unnotched compression and tension fatigue response of a 3-D braided composite was measured. Both gross compressive stress and tensile stress were plotted against cycles to failure to evaluate the fatigue life of these materials. Damage initiation and growth was monitored visually and by tracking compliance change during cycle loading. The intent was to establish by what means the strength of a 3-D architecture will start to degrade, at what point will it degrade beyond an acceptable level, and how this material will typically fail.

  19. Modeling the Nonlinear, Strain Rate Dependent Deformation of Woven Ceramic Matrix Composites With Hydrostatic Stress Effects Included

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Carney, Kelly S.

    2004-01-01

    An analysis method based on a deformation (as opposed to damage) approach has been developed to model the strain rate dependent, nonlinear deformation of woven ceramic matrix composites with a plain weave fiber architecture. In the developed model, the differences in the tension and compression response have also been considered. State variable based viscoplastic equations originally developed for metals have been modified to analyze the ceramic matrix composites. To account for the tension/compression asymmetry in the material, the effective stress and effective inelastic strain definitions have been modified. The equations have also been modified to account for the fact that in an orthotropic composite the in-plane shear stiffness is independent of the stiffness in the normal directions. The developed equations have been implemented into a commercially available transient dynamic finite element code, LS-DYNA, through the use of user defined subroutines (UMATs). The tensile, compressive, and shear deformation of a representative plain weave woven ceramic matrix composite are computed and compared to experimental results. The computed values correlate well to the experimental data, demonstrating the ability of the model to accurately compute the deformation response of woven ceramic matrix composites.

  20. External force back-projective composition and globally deformable optimization for 3-D coronary artery reconstruction.

    PubMed

    Yang, Jian; Cong, Weijian; Chen, Yang; Fan, Jingfan; Liu, Yue; Wang, Yongtian

    2014-02-21

    The clinical value of the 3D reconstruction of a coronary artery is important for the diagnosis and intervention of cardiovascular diseases. This work proposes a method based on a deformable model for reconstructing coronary arteries from two monoplane angiographic images acquired from different angles. First, an external force back-projective composition model is developed to determine the external force, for which the force distributions in different views are back-projected to the 3D space and composited in the same coordinate system based on the perspective projection principle of x-ray imaging. The elasticity and bending forces are composited as an internal force to maintain the smoothness of the deformable curve. Second, the deformable curve evolves rapidly toward the true vascular centerlines in 3D space and angiographic images under the combination of internal and external forces. Third, densely matched correspondence among vessel centerlines is constructed using a curve alignment method. The bundle adjustment method is then utilized for the global optimization of the projection parameters and the 3D structures. The proposed method is validated on phantom data and routine angiographic images with consideration for space and re-projection image errors. Experimental results demonstrate the effectiveness and robustness of the proposed method for the reconstruction of coronary arteries from two monoplane angiographic images. The proposed method can achieve a mean space error of 0.564 mm and a mean re-projection error of 0.349 mm.

  1. An experimental and theoretical study of creep in woven polymer composites

    NASA Astrophysics Data System (ADS)

    Govindarajan, S.

    The creep behavior of woven polymer composites has been investigated through both analytical and experimental methods with emphasis on the high temperature creep behavior. Experiments were carried out on composites manufactured through both autoclave (vacuum bag) and compression molding methods while the analysis included consideration of the geometry and constitution which were related to the curing cycle in a previous research. In the experimental study, composites made of epoxy-based and PMR-based composites were manufactured and tested. As these two resins have different operating temperature ranges, the experiments provided valuable information about their resistance to creep at elevated temperatures. The compression-molded PMR15 specimens were manufactured to contain different resin and void contents and were used to provide experimental data on the effects of varying constituent ratios. An automated material testing system along with a strain measurement system was designed and assembled to facilitate the experimental study. The experimental data was later analyzed using theoretical visco-elastic and geometric models. Initially an existing geometric model was used to analyze the creep behavior of the composite laminate. A modified version of this which considered the presence of voids in a Gaussian (random) distribution was developed later to consider the presence of a void-filled polymer matrix. Using the Arrhenius free energy equations, the high temperature behavior of the polymer and fibers were accounted for. Through these models, the material parameters associated with creep and other time dependent phenomena were obtained using inverse simulation on the experimental data. A new tool that extends this modeling to predict the behavior under any random loading was introduced. The modeling has been shown to successfully predict the creep and other visco-elastic behavior in the composite.

  2. 3D optical printing of piezoelectric nanoparticle-polymer composite materials.

    PubMed

    Kim, Kanguk; Zhu, Wei; Qu, Xin; Aaronson, Chase; McCall, William R; Chen, Shaochen; Sirbuly, Donald J

    2014-10-28

    Here we demonstrate that efficient piezoelectric nanoparticle-polymer composite materials can be optically printed into three-dimensional (3D) microstructures using digital projection printing. Piezoelectric polymers were fabricated by incorporating barium titanate (BaTiO3, BTO) nanoparticles into photoliable polymer solutions such as polyethylene glycol diacrylate and exposing to digital optical masks that could be dynamically altered to generate user-defined 3D microstructures. To enhance the mechanical-to-electrical conversion efficiency of the composites, the BTO nanoparticles were chemically modified with acrylate surface groups, which formed direct covalent linkages with the polymer matrix under light exposure. The composites with a 10% mass loading of the chemically modified BTO nanoparticles showed piezoelectric coefficients (d(33)) of ∼ 40 pC/N, which were over 10 times larger than composites synthesized with unmodified BTO nanoparticles and over 2 times larger than composites containing unmodified BTO nanoparticles and carbon nanotubes to boost mechanical stress transfer efficiencies. These results not only provide a tool for fabricating 3D piezoelectric polymers but lay the groundwork for creating highly efficient piezoelectric polymer materials via nanointerfacial tuning.

  3. Viability of 3 D Woven Carbon Cloth and Advanced Carbon-Carbon Ribs for Adaptive Deployable Entry Placement Technology (ADEPT) for Future NASA Missions

    NASA Technical Reports Server (NTRS)

    Venkatapathy, Ethiraj; Arnold, James O.; Peterson, K. H.; Blosser, M. L.

    2013-01-01

    This paper describes aerothermodynamic and thermal structural testing that demonstrate the viability of three dimensional woven carbon cloth and advanced carbon-carbon (ACC) ribs for use in the Adaptive Deployable Entry Placement Technology (ADEPT). ADEPT is an umbrella-like entry system that is folded for stowage in the launch vehicle's shroud and deployed prior to reaching the atmeopheric interface. A key feature of the ADEPT concept is a lower ballistic coefficient for delivery of a given payload than seen with conventional, rigid body entry systems. The benefits that accrue from the lower ballistic coefficient incllude factor-of-ten reductions of deceleration forces and entry heating. The former enables consideration of new classes of scientific instruments for solar system exploration while the latter enables the design of a more efficient thermal protection system. The carbon cloth base lined for ADEPT has a dual use in that it serves as the thermal protection system and as the "skin" that transfers aerdynamic deceleration loads to its umbrella-like substructure. Arcjet testing described in this paper was conducted for some of the higher heating conditions for a future Venus mission using the ADEPT concept, thereby showing that the carbon cloth can perform in a relevant entry environment. Recently completed the thermal structural testing of the cloth attached to a representative ACC rib design is also described. Finally, this paper describes a preliminary engineering level code, based on the arcjet data, that can be used to estimate cloth thickness for future ADEPT missions and to predict carbon cloth performance in future arcjet tests.

  4. Advanced 3D Ni(OH)2/CNT Gel Composite Electrodes for Supercapacitors

    NASA Astrophysics Data System (ADS)

    Cheng, Hanlin; Duong, Hai Minh

    2015-03-01

    In order to enhance the performance of supercapacitors, advanced 3D Porous CNT/Ni(OH)2 gel composite electrodes are developed in this work. Compared with previously reported graphene gel supercapacitors, our electrodes using 1D CNTs have smaller diffusion resistance due to a shorter ion transport path. The developed 3D xerogel composite electrodes demonstrate the success of a careful engineered guest/host materials interface. Initially, the CNT gels are coated on the nickel foam to form a 3D scaffold, which serves as a microscopic electrical conductive network. Then Ni(OH)2 are incorporated using a traditional electrodeposition method. In this work, two types of the 3D CNT-coated nickel foams are investigated. The gels can be used directly as hydrogels or dried in air to form xerogels. Both hydrogels and xerogels present 3D tangled CNT networks. It shows that the hydrogel composite electrodes with unbundled CNTs, though presenting high capacitances of 1400 F/g at low discharge rate, possess lower capacitances at higher discharge rate and a poor cycling performance of less than 23% retention. In contrast, the xerogel composite electrodes can overcome these limitations in terms of a satisfied discharge performance of 1200 F/g and a good cycling retention more than 85% due to a stronger Ni(OH)2/CNT interface. The CNT bundles in the xerogel electrodes formed during the drying process can give a flat surface with small curvature, which facilitate the Ni(OH)2 nucleation and growth. Thanks for the support from the A star R-265-000-424-305.

  5. Two-dimensional evaluation of 3D needled Cf/SiC composite fiber bundle surface

    NASA Astrophysics Data System (ADS)

    Wei, Jinhua; Lin, Bin; Cao, Xiaoyan; Zhang, Xiaofeng; Fang, Sheng

    2015-11-01

    The variations of fiber bundle surface microstructure have direct influence on the material performance, especially the friction and wear properties. Therefore, fiber bundle is the smallest evaluation unit of Cf/SiC composite surface. However, due to the anisotropy and inhomogeneity of Cf/SiC composite, it is difficult to evaluate the surface characteristics. Researchers think that two-dimensional evaluation is not suitable for the composites surface assessment any more because of its complex composition and varied surface structure. In this paper, a novel method is introduced for the evaluation of 3D needled Cf/SiC composite fiber bundle surface. On the level of Cf/SiC composite fiber bundle surface, two-dimensional evaluation method is adopted, with which the fiber bundle surface quality can be quantitatively evaluated by the two-dimensional surface roughness Ra. As long as the extracted surface profiles averagely distributed on Cf/SiC composite fiber bundle surface, with appropriate sampling length and sampling number, the mean value of Ra can estimate the whole surface roughness, thus reflecting the roughness degree of surface accurately. This study not only benefits the detection of 3D needled Cf/SiC composite fiber bundle surface quality, and lays a foundation on the evaluation of material functional features in further. And it corresponds to the convenient application in engineering practice.

  6. Interface Strength in NiAl-Mo Composites from 3D X-ray Microdiffraction

    SciTech Connect

    Barabash, Rozaliya; Bei, Hongbin; Gao, Yanfei; Ice, Gene E

    2011-01-01

    The depth-dependent strain gradients near buried interfaces in a model system of NiAl-Mo composite were nondestructively probed with 3-D X-ray microdiffraction. Coupled with micromechanical analysis, our study shows that the relaxation of the residual thermal strains in the NiAl-Mo composites results in the formation of a near-surface 'slip zone' with large strain gradients in both the reinforcing Mo fibers and NiAl matrix. Based on these results an approach to calculate the fiber-matrix interface strength for composite materials is suggested.

  7. Fatigue Life Prediction of 2D Woven Ceramic-Matrix Composites at Room and Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2017-02-01

    In this paper, the fatigue life of 2D woven ceramic-matrix composites, i.e., SiC/SiC, SiC/Si-N-C, SiC/Si-B4C, and Nextel 610™/Aluminosilicate, at room and elevated temperatures has been predicted using the micromechanics approach. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. The Budiansky-Hutchinson-Evans shear-lag model was used to describe the microstress field of the damaged composite considering fibers failure. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The interface shear stress and fibers strength degradation model and oxidation region propagation model have been adopted to analyze the fatigue and oxidation effects on fatigue life of the composite, which is controlled by interface frictional slip and diffusion of oxygen gas through matrix multicrackings. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface/fiber oxidation model, interface wear model and fibers statistical failure model at elevated temperatures, based on the assumption that the fiber strength is subjected to two-parameter Weibull distribution and the load carried by broken and intact fibers satisfy the Global Load Sharing (GLS) criterion. When the broken fibers fraction approaches to the critical value, the composites fatigue fractures. The fatigue life S-N curves of 2D SiC/SiC, SiC/Si-N-C, SiC/Si-B4C, and Nextel 610™/Aluminosilicate composites at room temperature and 800, 1000 and 1200 °C in air and steam have been predicted.

  8. Fatigue Life Prediction of 2D Woven Ceramic-Matrix Composites at Room and Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2017-03-01

    In this paper, the fatigue life of 2D woven ceramic-matrix composites, i.e., SiC/SiC, SiC/Si-N-C, SiC/Si-B4C, and Nextel 610™/Aluminosilicate, at room and elevated temperatures has been predicted using the micromechanics approach. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. The Budiansky-Hutchinson-Evans shear-lag model was used to describe the microstress field of the damaged composite considering fibers failure. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The interface shear stress and fibers strength degradation model and oxidation region propagation model have been adopted to analyze the fatigue and oxidation effects on fatigue life of the composite, which is controlled by interface frictional slip and diffusion of oxygen gas through matrix multicrackings. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface/fiber oxidation model, interface wear model and fibers statistical failure model at elevated temperatures, based on the assumption that the fiber strength is subjected to two-parameter Weibull distribution and the load carried by broken and intact fibers satisfy the Global Load Sharing (GLS) criterion. When the broken fibers fraction approaches to the critical value, the composites fatigue fractures. The fatigue life S- N curves of 2D SiC/SiC, SiC/Si-N-C, SiC/Si-B4C, and Nextel 610™/Aluminosilicate composites at room temperature and 800, 1000 and 1200 °C in air and steam have been predicted.

  9. Thermal shock behavior of two-dimensional woven fiber-reinforced ceramic composites

    SciTech Connect

    Wang, H.; Singh, R.N.; Lowden, R.A.

    1996-07-01

    The thermal shock behavior of three types of two-dimensional woven, continuous fiber-reinforced (Nextel{trademark} 312 (3M Co., St. Paul, MN) or Nicalon{trademark} (Nippon Carbon, Tokyo, Japan)) ceramic matrix (silicon carbide matrix that had been processed by chemical vapor infiltration or polymer impregnation and pyrolysis) composites was studied using the water-quench technique. Thermal-shock-induced damage was characterized by a destructive technique of four-point flexure and a nondestructive technique of Young`s modulus measurement by the dynamic resonance method. Compared with monolithic ceramics, the continuous fiber-reinforced ceramic composites were capable of preventing catastrophic failure that was caused by thermal shock. Analysis of the results that were based on the stresses that were generated by thermal shock and the mismatch of thermal expansion between fibers and matrices suggested possible mechanisms of the thermal shock damage. Preliminary results showed evidence of matrix cracking and delamination because of the thermal shock damage. The feasibility of using the nondestructive technique to detect thermal shock damage also was demonstrated.

  10. Multi-shape active composites by 3D printing of digital shape memory polymers

    NASA Astrophysics Data System (ADS)

    Wu, Jiangtao; Yuan, Chao; Ding, Zhen; Isakov, Michael; Mao, Yiqi; Wang, Tiejun; Dunn, Martin L.; Qi, H. Jerry

    2016-04-01

    Recent research using 3D printing to create active structures has added an exciting new dimension to 3D printing technology. After being printed, these active, often composite, materials can change their shape over time; this has been termed as 4D printing. In this paper, we demonstrate the design and manufacture of active composites that can take multiple shapes, depending on the environmental temperature. This is achieved by 3D printing layered composite structures with multiple families of shape memory polymer (SMP) fibers – digital SMPs - with different glass transition temperatures (Tg) to control the transformation of the structure. After a simple single-step thermomechanical programming process, the fiber families can be sequentially activated to bend when the temperature is increased. By tuning the volume fraction of the fibers, bending deformation can be controlled. We develop a theoretical model to predict the deformation behavior for better understanding the phenomena and aiding the design. We also design and print several flat 2D structures that can be programmed to fold and open themselves when subjected to heat. With the advantages of an easy fabrication process and the controllable multi-shape memory effect, the printed SMP composites have a great potential in 4D printing applications.

  11. Multi-shape active composites by 3D printing of digital shape memory polymers.

    PubMed

    Wu, Jiangtao; Yuan, Chao; Ding, Zhen; Isakov, Michael; Mao, Yiqi; Wang, Tiejun; Dunn, Martin L; Qi, H Jerry

    2016-04-13

    Recent research using 3D printing to create active structures has added an exciting new dimension to 3D printing technology. After being printed, these active, often composite, materials can change their shape over time; this has been termed as 4D printing. In this paper, we demonstrate the design and manufacture of active composites that can take multiple shapes, depending on the environmental temperature. This is achieved by 3D printing layered composite structures with multiple families of shape memory polymer (SMP) fibers - digital SMPs - with different glass transition temperatures (Tg) to control the transformation of the structure. After a simple single-step thermomechanical programming process, the fiber families can be sequentially activated to bend when the temperature is increased. By tuning the volume fraction of the fibers, bending deformation can be controlled. We develop a theoretical model to predict the deformation behavior for better understanding the phenomena and aiding the design. We also design and print several flat 2D structures that can be programmed to fold and open themselves when subjected to heat. With the advantages of an easy fabrication process and the controllable multi-shape memory effect, the printed SMP composites have a great potential in 4D printing applications.

  12. Meso-Scale Damage Simulation of 3D Braided Composites under Quasi-Static Axial Tension

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Mao, Chunjian; Zhou, Yexin

    2017-01-01

    The microstructure of 3D braided composites is composed of three phases: braiding yarn, matrix and interface. In this paper, a representative unit-cell (RUC) model including these three phases is established. Coupling with the periodical boundary condition, the damage behavior of 3D braided composites under quasi-static axial tension is simulated by using finite element method based on this RUC model. An anisotropic damage model based on Murakami damage theory is proposed to predict the damage evolution of yarns and matrix; a damage-friction combination interface constitutive model is adopted to predict the interface debonding behavior. A user material subroutine (VUMAT) involving these damage models is developed and implemented in the finite element software ABAQUS/Explicit. The whole process of damage evolution of 3D braided composites under quasi-static axial tension with typical braiding angles is simulated, and the damage mechanisms are revealed in detail in the simulation process. The tensile strength properties of the braided composites are predicted from the calculated stress-strain curves. Numerical results agree with the available experiment data and thus validates the proposed damage analysis model. The effects of certain material parameters on the predicted stress-strain responses are also discussed by numerical parameter study.

  13. Multi-shape active composites by 3D printing of digital shape memory polymers

    PubMed Central

    Wu, Jiangtao; Yuan, Chao; Ding, Zhen; Isakov, Michael; Mao, Yiqi; Wang, Tiejun; Dunn, Martin L.; Qi, H. Jerry

    2016-01-01

    Recent research using 3D printing to create active structures has added an exciting new dimension to 3D printing technology. After being printed, these active, often composite, materials can change their shape over time; this has been termed as 4D printing. In this paper, we demonstrate the design and manufacture of active composites that can take multiple shapes, depending on the environmental temperature. This is achieved by 3D printing layered composite structures with multiple families of shape memory polymer (SMP) fibers – digital SMPs - with different glass transition temperatures (Tg) to control the transformation of the structure. After a simple single-step thermomechanical programming process, the fiber families can be sequentially activated to bend when the temperature is increased. By tuning the volume fraction of the fibers, bending deformation can be controlled. We develop a theoretical model to predict the deformation behavior for better understanding the phenomena and aiding the design. We also design and print several flat 2D structures that can be programmed to fold and open themselves when subjected to heat. With the advantages of an easy fabrication process and the controllable multi-shape memory effect, the printed SMP composites have a great potential in 4D printing applications. PMID:27071543

  14. Intelligent Multi-scale Sensors for Damage Identification and Mitigation in Woven Composites for Aerospace Structural Applications

    DTIC Science & Technology

    2012-08-15

    resulting from project: Journal Publications 1. R. Garret , K. Peters and M. A. Zikry (2009), “In-situ Impact-induced Damage Assessment of Woven...Polymer Composites,” to be submitted. Conference Proceedings Publications 1. R. Garret , J. Pearson, K. Peters and M. Zikry (2007...Structures Technologies for Civil, Mechanical and Aerospace Systems, Smart Materials and Structures, San Diego, CA, 6529. 2. R. Garret , K. Peters

  15. The influence of FLiNaK salt impregnation on the mechanical properties of a 2D woven C/C composite

    NASA Astrophysics Data System (ADS)

    Zhang, Dongsheng; Xia, Huihao; Yang, Xinmei; Feng, Shanglei; Song, Jinliang; Zhou, Xingtai

    2017-03-01

    Impregnating of molten LiF-NaF-KF salt (LiF-NaF-KF: 46.5-11.5-42 mol%, FLiNaK) into a 2D woven C/C composite was performed at 650 °C under different pressure. The weight gain and mechanical properties change of the 2D woven C/C composite after FLiNaK salt impregnation were measured. The FLiNaK salt distribution into the 2D woven C/C composite was observed by X-ray computed tomography (X-ray CT) and scanning electron microscopy. The results showed that the weight gain of the 2D woven C/C composite increased with increasing impregnating pressure. In X-ray CT images, FLiNaK salt was distributed into the open pores and fissures among fiber bundles and neighboring plies. The interlaminar shear strength, compressive strength, and flexural strength of the 2D woven C/C composite increased with the increase of weight gain. The influence of FLiNaK salt impregnation on the mechanical properties was attributed to the coupling effect of re-densification of FLiNaK salt impregnation and residual stress formed in 2D woven C/C composite.

  16. Mechanical performance and parameter sensitivity analysis of 3D braided composites joints.

    PubMed

    Wu, Yue; Nan, Bo; Chen, Liang

    2014-01-01

    3D braided composite joints are the important components in CFRP truss, which have significant influence on the reliability and lightweight of structures. To investigate the mechanical performance of 3D braided composite joints, a numerical method based on the microscopic mechanics is put forward, the modeling technologies, including the material constants selection, element type, grid size, and the boundary conditions, are discussed in detail. Secondly, a method for determination of ultimate bearing capacity is established, which can consider the strength failure. Finally, the effect of load parameters, geometric parameters, and process parameters on the ultimate bearing capacity of joints is analyzed by the global sensitivity analysis method. The results show that the main pipe diameter thickness ratio γ, the main pipe diameter D, and the braided angle α are sensitive to the ultimate bearing capacity N.

  17. Mechanical Performance and Parameter Sensitivity Analysis of 3D Braided Composites Joints

    PubMed Central

    Wu, Yue; Nan, Bo; Chen, Liang

    2014-01-01

    3D braided composite joints are the important components in CFRP truss, which have significant influence on the reliability and lightweight of structures. To investigate the mechanical performance of 3D braided composite joints, a numerical method based on the microscopic mechanics is put forward, the modeling technologies, including the material constants selection, element type, grid size, and the boundary conditions, are discussed in detail. Secondly, a method for determination of ultimate bearing capacity is established, which can consider the strength failure. Finally, the effect of load parameters, geometric parameters, and process parameters on the ultimate bearing capacity of joints is analyzed by the global sensitivity analysis method. The results show that the main pipe diameter thickness ratio γ, the main pipe diameter D, and the braided angle α are sensitive to the ultimate bearing capacity N. PMID:25121121

  18. Biomimetic staggered composites with highly enhanced energy dissipation: Modeling, 3D printing, and testing

    NASA Astrophysics Data System (ADS)

    Zhang, Pu; Heyne, Mary A.; To, Albert C.

    2015-10-01

    We investigate the damping enhancement in a class of biomimetic staggered composites via a combination of design, modeling, and experiment. In total, three kinds of staggered composites are designed by mimicking the structure of bone and nacre. These composite designs are realized by 3D printing a rigid plastic and a viscous elastomer simultaneously. Greatly-enhanced energy dissipation in the designed composites is observed from both the experimental results and theoretical prediction. The designed polymer composites have loss modulus up to ~500 MPa, higher than most of the existing polymers. In addition, their specific loss modulus (up to 0.43 km2/s2) is among the highest of damping materials. The damping enhancement is attributed to the large shear deformation of the viscous soft matrix and the large strengthening effect from the rigid inclusion phase.

  19. Shear induced alignment of short nanofibers in 3D printed polymer composites

    NASA Astrophysics Data System (ADS)

    Erdem Yunus, Doruk; Shi, Wentao; Sohrabi, Salman; Liu, Yaling

    2016-12-01

    3D printing of composite materials offers an opportunity to combine the desired properties of composite materials with the flexibility of additive manufacturing in geometric shape and complexity. In this paper, the shear-induced alignment of aluminum oxide nanowires during stereolithography printing was utilized to fabricate a nanowire reinforced polymer composite. To align the fibers, a lateral oscillation mechanism was implemented and combined with wall pattern printing technique to generate shear flow in both vertical and horizontal directions. A series of specimens were fabricated for testing the composite material’s tensile strength. The results showed that mechanical properties of the composite were improved by reinforcement of nanofibers through shear induced alignment. The improvement of tensile strength was approximately ∼28% by aligning the nanowires at 5 wt% (∼1.5% volume fraction) loading of aluminum oxide nanowires.

  20. Shear induced alignment of short nanofibers in 3D printed polymer composites.

    PubMed

    Yunus, Doruk Erdem; Shi, Wentao; Sohrabi, Salman; Liu, Yaling

    2016-12-09

    3D printing of composite materials offers an opportunity to combine the desired properties of composite materials with the flexibility of additive manufacturing in geometric shape and complexity. In this paper, the shear-induced alignment of aluminum oxide nanowires during stereolithography printing was utilized to fabricate a nanowire reinforced polymer composite. To align the fibers, a lateral oscillation mechanism was implemented and combined with wall pattern printing technique to generate shear flow in both vertical and horizontal directions. A series of specimens were fabricated for testing the composite material's tensile strength. The results showed that mechanical properties of the composite were improved by reinforcement of nanofibers through shear induced alignment. The improvement of tensile strength was approximately ∼28% by aligning the nanowires at 5 wt% (∼1.5% volume fraction) loading of aluminum oxide nanowires.

  1. Characterizing the Properties of a Woven SiC/SiC Composite Using W-CEMCAN Computer Code

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Mital, Subodh K.; DiCarlo, James A.

    1999-01-01

    A micromechanics based computer code to predict the thermal and mechanical properties of woven ceramic matrix composites (CMC) is developed. This computer code, W-CEMCAN (Woven CEramic Matrix Composites ANalyzer), predicts the properties of two-dimensional woven CMC at any temperature and takes into account various constituent geometries and volume fractions. This computer code is used to predict the thermal and mechanical properties of an advanced CMC composed of 0/90 five-harness (5 HS) Sylramic fiber which had been chemically vapor infiltrated (CVI) with boron nitride (BN) and SiC interphase coatings and melt-infiltrated (MI) with SiC. The predictions, based on the bulk constituent properties from the literature, are compared with measured experimental data. Based on the comparison. improved or calibrated properties for the constituent materials are then developed for use by material developers/designers. The computer code is then used to predict the properties of a composite with the same constituents but with different fiber volume fractions. The predictions are compared with measured data and a good agreement is achieved.

  2. Pt-Free Counter Electrodes with Carbon Black and 3D Network Epoxy Polymer Composites

    NASA Astrophysics Data System (ADS)

    Kang, Gyeongho; Choi, Jongmin; Park, Taiho

    2016-03-01

    Carbon black (CB) and a 3D network epoxy polymer composite, representing dual functions for conductive corrosion protective layer (CCPL) and catalytic layer (CL) by the control of CB weight ratio against polymer is developed. Our strategy provides a proper approach which applies high catalytic ability and chemical stability of CB in corrosive triiodide/iodide (I3-/I-) redox electrolyte system. The CB and a 3D network epoxy polymer composite coated on the stainless steel (SS) electrode to alternate counter electrodes in dye sensitized solar cells (DSSCs). A two-step spray pyrolysis process is used to apply a solution containing epoxy monomers and a polyfunctional amine hardener with 6 wt% CB to a SS substrate, which forms a CCPL. Subsequently, an 86 wt% CB is applied to form a CL. The excellent catalytic properties and corrosion protective properties of the CB and 3D network epoxy polymer composites produce efficient counter electrodes that can replace fluorine-doped tin oxide (FTO) with CCPL/SS and Pt/FTO with CL/CCPL/SS in DSSCs. This approach provides a promising approach to the development of efficient, stable, and cheap solar cells, paving the way for large-scale commercialization.

  3. Pt-Free Counter Electrodes with Carbon Black and 3D Network Epoxy Polymer Composites

    PubMed Central

    Kang, Gyeongho; Choi, Jongmin; Park, Taiho

    2016-01-01

    Carbon black (CB) and a 3D network epoxy polymer composite, representing dual functions for conductive corrosion protective layer (CCPL) and catalytic layer (CL) by the control of CB weight ratio against polymer is developed. Our strategy provides a proper approach which applies high catalytic ability and chemical stability of CB in corrosive triiodide/iodide (I3−/I−) redox electrolyte system. The CB and a 3D network epoxy polymer composite coated on the stainless steel (SS) electrode to alternate counter electrodes in dye sensitized solar cells (DSSCs). A two-step spray pyrolysis process is used to apply a solution containing epoxy monomers and a polyfunctional amine hardener with 6 wt% CB to a SS substrate, which forms a CCPL. Subsequently, an 86 wt% CB is applied to form a CL. The excellent catalytic properties and corrosion protective properties of the CB and 3D network epoxy polymer composites produce efficient counter electrodes that can replace fluorine-doped tin oxide (FTO) with CCPL/SS and Pt/FTO with CL/CCPL/SS in DSSCs. This approach provides a promising approach to the development of efficient, stable, and cheap solar cells, paving the way for large-scale commercialization. PMID:26961256

  4. Microwave dielectric characterisation of 3D-printed BaTiO3/ABS polymer composites

    PubMed Central

    Castles, F.; Isakov, D.; Lui, A.; Lei, Q.; Dancer, C. E. J.; Wang, Y.; Janurudin, J. M.; Speller, S. C.; Grovenor, C. R. M.; Grant, P. S.

    2016-01-01

    3D printing is used extensively in product prototyping and continues to emerge as a viable option for the direct manufacture of final parts. It is known that dielectric materials with relatively high real permittivity—which are required in important technology sectors such as electronics and communications—may be 3D printed using a variety of techniques. Among these, the fused deposition of polymer composites is particularly straightforward but the range of dielectric permittivities available through commercial feedstock materials is limited. Here we report on the fabrication of a series of composites composed of various loadings of BaTiO3 microparticles in the polymer acrylonitrile butadiene styrene (ABS), which may be used with a commercial desktop 3D printer to produce printed parts containing user-defined regions with high permittivity. The microwave dielectric properties of printed parts with BaTiO3 loadings up to 70 wt% were characterised using a 15 GHz split post dielectric resonator and had real relative permittivities in the range 2.6–8.7 and loss tangents in the range 0.005–0.027. Permittivities were reproducible over the entire process, and matched those of bulk unprinted materials, to within ~1%, suggesting that the technique may be employed as a viable manufacturing process for dielectric composites. PMID:26940381

  5. Microwave dielectric characterisation of 3D-printed BaTiO3/ABS polymer composites

    NASA Astrophysics Data System (ADS)

    Castles, F.; Isakov, D.; Lui, A.; Lei, Q.; Dancer, C. E. J.; Wang, Y.; Janurudin, J. M.; Speller, S. C.; Grovenor, C. R. M.; Grant, P. S.

    2016-03-01

    3D printing is used extensively in product prototyping and continues to emerge as a viable option for the direct manufacture of final parts. It is known that dielectric materials with relatively high real permittivity—which are required in important technology sectors such as electronics and communications—may be 3D printed using a variety of techniques. Among these, the fused deposition of polymer composites is particularly straightforward but the range of dielectric permittivities available through commercial feedstock materials is limited. Here we report on the fabrication of a series of composites composed of various loadings of BaTiO3 microparticles in the polymer acrylonitrile butadiene styrene (ABS), which may be used with a commercial desktop 3D printer to produce printed parts containing user-defined regions with high permittivity. The microwave dielectric properties of printed parts with BaTiO3 loadings up to 70 wt% were characterised using a 15 GHz split post dielectric resonator and had real relative permittivities in the range 2.6–8.7 and loss tangents in the range 0.005–0.027. Permittivities were reproducible over the entire process, and matched those of bulk unprinted materials, to within ~1%, suggesting that the technique may be employed as a viable manufacturing process for dielectric composites.

  6. Microwave dielectric characterisation of 3D-printed BaTiO3/ABS polymer composites.

    PubMed

    Castles, F; Isakov, D; Lui, A; Lei, Q; Dancer, C E J; Wang, Y; Janurudin, J M; Speller, S C; Grovenor, C R M; Grant, P S

    2016-03-04

    3D printing is used extensively in product prototyping and continues to emerge as a viable option for the direct manufacture of final parts. It is known that dielectric materials with relatively high real permittivity-which are required in important technology sectors such as electronics and communications-may be 3D printed using a variety of techniques. Among these, the fused deposition of polymer composites is particularly straightforward but the range of dielectric permittivities available through commercial feedstock materials is limited. Here we report on the fabrication of a series of composites composed of various loadings of BaTiO3 microparticles in the polymer acrylonitrile butadiene styrene (ABS), which may be used with a commercial desktop 3D printer to produce printed parts containing user-defined regions with high permittivity. The microwave dielectric properties of printed parts with BaTiO3 loadings up to 70 wt% were characterised using a 15 GHz split post dielectric resonator and had real relative permittivities in the range 2.6-8.7 and loss tangents in the range 0.005-0.027. Permittivities were reproducible over the entire process, and matched those of bulk unprinted materials, to within ~1%, suggesting that the technique may be employed as a viable manufacturing process for dielectric composites.

  7. Picture frame experiment and analytical model of the pre-impregnated woven fabric composite

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Sun, Liping

    2009-12-01

    Pre-impregnated woven fabric composite (PWFC) is a kind of visco-elastic material which requires picture frame experiment, a sort of useful material characterization methodology, to test the shear properties. The PWFC specimen used in the experiment is 165mm×165mm minus a 25mm×25mm square at each corner in order to allow free motion of the frame. The screw Instron is applied to provide a constant displacement rate. Thus, load-displacement curve is obtained. Through analysis of every constituent mutual interaction and deformation mechanism of the PWFC, the shear deformation is divided by shear and compaction phases and a picture frame analytical model is developed to account for large shear deformation, as well as to calculate the stress and stiffness of the fabric according to different phases. The model includes the resin damping function and the crossover friction of the warp and weft tows in the shearing phase. In the compaction phase, resin will be driven from the inter-tow region and the tows are interacted. Consequently, a lateral compaction shear resistance moment is occurred. The picture frame experiment curve is used to verify the analytical model curve and the two curves are in good agreement.

  8. Picture frame experiment and analytical model of the pre-impregnated woven fabric composite

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Sun, Liping

    2010-03-01

    Pre-impregnated woven fabric composite (PWFC) is a kind of visco-elastic material which requires picture frame experiment, a sort of useful material characterization methodology, to test the shear properties. The PWFC specimen used in the experiment is 165mm×165mm minus a 25mm×25mm square at each corner in order to allow free motion of the frame. The screw Instron is applied to provide a constant displacement rate. Thus, load-displacement curve is obtained. Through analysis of every constituent mutual interaction and deformation mechanism of the PWFC, the shear deformation is divided by shear and compaction phases and a picture frame analytical model is developed to account for large shear deformation, as well as to calculate the stress and stiffness of the fabric according to different phases. The model includes the resin damping function and the crossover friction of the warp and weft tows in the shearing phase. In the compaction phase, resin will be driven from the inter-tow region and the tows are interacted. Consequently, a lateral compaction shear resistance moment is occurred. The picture frame experiment curve is used to verify the analytical model curve and the two curves are in good agreement.

  9. Effects of electromagnetic field frequencies on chondrocytes in 3D cell-printed composite constructs.

    PubMed

    Yi, Hee-Gyeong; Kang, Kyung Shin; Hong, Jung Min; Jang, Jinah; Park, Moon Nyeo; Jeong, Young Hun; Cho, Dong-Woo

    2016-07-01

    In cartilage tissue engineering, electromagnetic field (EMF) therapy has been reported to have a modest effect on promoting cartilage regeneration. However, these studies were conducted using different frequencies of EMF to stimulate chondrocytes. Thus, it is necessary to investigate the effect of EMF frequency on cartilage formation. In addition to the stimulation, a scaffold is required to satisfy the characteristics of cartilage such as its hydrated and dense extracellular matrix, and a mechanical resilience to applied loads. Therefore, we 3D-printed a composite construct composed of a polymeric framework and a chondrocyte-laden hydrogel. Here, we observed frequency-dependent positive and negative effects on chondrogenesis using a 3D cell-printed cartilage tissue. We found that a frequency of 45 Hz promoted gene expression and secretion of extracellular matrix molecules of chondrocytes. In contrast, a frequency of 7.5 Hz suppressed chondrogenic differentiation in vitro. Additionally, the EMF-treated composite constructs prior to implantation showed consistent results with those of in vitro, suggesting that in vitro pre-treatment with different EMF frequencies provides different capabilities for the enhancement of cartilage formation in vivo. This correlation between EMF frequency and 3D-printed chondrocytes suggests the necessity for optimization of EMF parameters when this physical stimulus is applied to engineered cartilage. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1797-1804, 2016.

  10. Application of robust color composite fringe in flip-chip solder bump 3-D measurement

    NASA Astrophysics Data System (ADS)

    Kuo, Chung-Feng Jeffrey; Wu, Han-Cheng

    2017-04-01

    This study developed a 3-D measurement system based on flip-chip solder bump, used fringes with different modulation intensities in color channels, in order to produce color composite fringe with robustness, and proposed a multi-channel composite phase unwrapping algorithm, which uses fringe modulation weights of different channels to recombine the phase information for better measurement accuracy and stability. The experimental results showed that the average measurement accuracy is 0.43μm and the standard deviation is 1.38 μm. The results thus proved that the proposed 3-D measurement system is effective in measuring a plane with a height of 50 μm. In the flip-chip solder bump measuring experiment, different fringe modulation configurations were tested to overcome the problem of reflective coefficient between the flip-chip base board and the solder bump. The proposed system has a good measurement results and robust stability in the solder bump measurement, and can be used for the measurement of 3-D information for micron flip-chip solder bump application.

  11. A Shell/3D Modeling Technique for Delaminations in Composite Laminates

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald

    1999-01-01

    A shell/3D modeling technique was developed for which a local solid finite element model is used only in the immediate vicinity of the delamination front. The goal was to combine the accuracy of the full three-dimensional solution with the computational efficiency of a plate or shell finite element model. Multi-point constraints provide a kinematically compatible interface between the local 3D model and the global structural model which has been meshed with plate or shell finite elements. For simple double cantilever beam (DCB), end notched flexure (ENF), and single leg bending (SLB) specimens, mixed mode energy release rate distributions were computed across the width from nonlinear finite element analyses using the virtual crack closure technique. The analyses served to test the accuracy of the shell/3D technique for the pure mode I case (DCB), mode II case (ENF) and a mixed mode I/II case (SLB). Specimens with a unidirectional layup where the delamination is located between two 0 plies, as well as a multidirectional layup where the delamination is located between two non-zero degree plies, were simulated. For a local 3D model extending to a minimum of about three specimen thicknesses in front of and behind the delamination front, the results were in good agreement with mixed mode strain energy release rates obtained from computations where the entire specimen had been modeled with solid elements. For large built-up composite structures modeled with plate elements, the shell/3D modeling technique offers a great potential, since only a relatively small section in the vicinity of the delamination front needs to be modeled with solid elements.

  12. An experimental and numerical study of 3-D braided structural textile composites

    SciTech Connect

    Abusafieh, A.; Kalidindi, S.R.; Franco, E.

    1994-12-31

    It has been reported in literature that isostrain models (also known as Fabric Geometry Models) provide good predictions of the elastic moduli of three-dimensional textile composites. This study reports a critical evaluation of the accuracy of the isostrain models by comparing the predictions against experimental measurements as well as finite element simulations of representative unit cells of the 3-D braided composites, over a range of braid angles and volume fractions. The accuracy of the isostrain model is found to be highly sensitive to the braid angles and the fraction of lay-in axial fibers in the composite system. Good correlations between isostrain model predictions of elastic moduli and measurements were observed when the loading direction is oriented along one of the fiber directions and is significantly away from the other fiber systems in the unit cell. In other situations, however, the isostrain model predictions were in significant errors. This study also reports on the influence of various modeling parameters in the development of finite element models for the simulation of the 3-D textile composite unit cells.

  13. Stability of 3D Textile Composite Reinforcement Simulations: Solutions to Spurious Transverse Modes

    NASA Astrophysics Data System (ADS)

    Mathieu, S.; Hamila, N.; Dupé, F.; Descamps, C.; Boisse, P.

    2016-08-01

    The simulation of thick 3D composite reinforcement forming brings to light new modeling challenges. The specific anisotropic material behavior due to the possible slippage between fibers induces, among other phenomena, the development of spurious transverse modes in bending-dominated 3D simulations. To obtain coherent finite element responses, two solutions are proposed. The first one uses a simple assumed strain formulation usually prescribed to prevent volumetric locking. This solution avoids spurious transverse modes by stiffening of the hourglass modes. Nevertheless the deformation obtained by this approach still suffers from the inability of the standard continuum mechanics of Cauchy to describe fibrous material deformation. The second proposed approach is based on the introduction of a bending stiffness which both avoids the spurious transverse modes and also improves the global behavior of the element formulation by enriching the underlying continuum. To emphasize the differences between different formulations, element stiffnesses are explicitly calculated and compared.

  14. A Periosteum-Inspired 3D Hydrogel-Bioceramic Composite for Enhanced Bone Regeneration .

    PubMed

    Chun, Yong Yao; Wang, Jun Kit; Tan, Nguan Soon; Chan, Peggy Puk Yik; Tan, Timothy Thatt Yang; Choong, Cleo

    2016-02-01

    A 3D injectable hydrogel-bioceramic composite consisting of gelatin-3-(4-hydroxyphenyl) propionic acid (Gtn-HPA) and carboxymethyl cellulose-tyramine (CMC-Tyr), incorporated with fish scale-derived calcium phosphate (CaP), is developed for bone applications. The hydrogel-bioceramic composite has significantly improved the elastic modulus compared to the non-filled hydrogel, of which the addition of 10 w/v% CaP showed zero order fluorescein isothiocyanate (FITC)-dextran release profile and a significantly higher proliferation rate of encapsulated cells. All the samples promote the nucleation and growth of CaP minerals when exposed to 1× SBF. Overall, the hydrogel-bioceramic composite with 10 w/v% CaP can potentially be used as a periosteum-mimicking membrane to facilitate bone regeneration.

  15. Calcium phosphate/microgel composites for 3D powderbed printing of ceramic materials.

    PubMed

    Birkholz, Mandy-Nicole; Agrawal, Garima; Bergmann, Christian; Schröder, Ricarda; Lechner, Sebastian J; Pich, Andrij; Fischer, Horst

    2016-06-01

    Composites of microgels and calcium phosphates are promising as drug delivery systems and basic components for bone substitute implants. In this study, we synthesized novel composite materials consisting of pure β-tricalcium phosphate and stimuli-responsive poly(N-vinylcaprolactam-co-acetoacetoxyethyl methacrylate-co-vinylimidazole) microgels. The chemical composition, thermal properties and morphology for obtained composites were extensively characterized by Fourier transform infrared, X-ray photoelectron spectroscopy, IGAsorp moisture sorption analyzer, thermogravimetric analysis, granulometric analysis, ESEM, energy dispersive X-ray spectroscopy and TEM. Mechanical properties of the composites were evaluated by ball-on-three-balls test to determine the biaxial strength. Furthermore, initial 3D powderbed-based printing tests were conducted with spray-dried composites and diluted 2-propanol as a binder to evaluate a new binding concept for β-tricalcium phosphate-based granulates. The printed ceramic bodies were characterized before and after a sintering step by ESEM. The hypothesis that the microgels act as polymer adhesive agents by efficient chemical interactions with the β-tricalcium phosphate particles was confirmed. The obtained composites can be used for the development of new scaffolds.

  16. Fracture, failure and compression behaviour of a 3D interconnected carbon aerogel (Aerographite) epoxy composite

    DOE PAGES

    Chandrasekaran, S.; Liebig, W. V.; Mecklenberg, M.; ...

    2015-11-04

    Aerographite (AG) is a mechanically robust, lightweight synthetic cellular material, which consists of a 3D interconnected network of tubular carbon [1]. The presence of open channels in AG aids to infiltrate them with polymer matrices, thereby yielding an electrical conducting and lightweight composite. Aerographite produced with densities in the range of 7–15 mg/cm3 was infiltrated with a low viscous epoxy resin by means of vacuum infiltration technique. Detailed morphological and structural investigations on synthesized AG and AG/epoxy composite were performed by scanning electron microscopic techniques. Our present study investigates the fracture and failure of AG/epoxy composites and its energy absorptionmore » capacity under compression. The composites displayed an extended plateau region when uni-axially compressed, which led to an increase in energy absorption of ~133% per unit volume for 1.5 wt% of AG, when compared to pure epoxy. Preliminary results on fracture toughness showed an enhancement of ~19% in KIC for AG/epoxy composites with 0.45 wt% of AG. Furthermore, our observations of fractured surfaces under scanning electron microscope gives evidence of pull-out of arms of AG tetrapod, interface and inter-graphite failure as the dominating mechanism for the toughness improvement in these composites. These observations were consistent with the results obtained from photoelasticity experiments on a thin film AG/epoxy model composite.« less

  17. Fracture, failure and compression behaviour of a 3D interconnected carbon aerogel (Aerographite) epoxy composite

    SciTech Connect

    Chandrasekaran, S.; Liebig, W. V.; Mecklenberg, M.; Fiedler, B.; Smazna, D.; Adelung, R.; Schulte, K.

    2015-11-04

    Aerographite (AG) is a mechanically robust, lightweight synthetic cellular material, which consists of a 3D interconnected network of tubular carbon [1]. The presence of open channels in AG aids to infiltrate them with polymer matrices, thereby yielding an electrical conducting and lightweight composite. Aerographite produced with densities in the range of 7–15 mg/cm3 was infiltrated with a low viscous epoxy resin by means of vacuum infiltration technique. Detailed morphological and structural investigations on synthesized AG and AG/epoxy composite were performed by scanning electron microscopic techniques. Our present study investigates the fracture and failure of AG/epoxy composites and its energy absorption capacity under compression. The composites displayed an extended plateau region when uni-axially compressed, which led to an increase in energy absorption of ~133% per unit volume for 1.5 wt% of AG, when compared to pure epoxy. Preliminary results on fracture toughness showed an enhancement of ~19% in KIC for AG/epoxy composites with 0.45 wt% of AG. Furthermore, our observations of fractured surfaces under scanning electron microscope gives evidence of pull-out of arms of AG tetrapod, interface and inter-graphite failure as the dominating mechanism for the toughness improvement in these composites. These observations were consistent with the results obtained from photoelasticity experiments on a thin film AG/epoxy model composite.

  18. Multi scale analysis by acoustic emission of damage mechanisms in natural fibre woven fabrics/epoxy composites.

    NASA Astrophysics Data System (ADS)

    Bonnafous, C.; Touchard, F.; Chocinski-Arnault, L.

    2010-06-01

    This paper proposes to develop an experimental program to characterize the type and the development of damage in composite with complex microstructure. A multi-scale analysis by acoustic emission has been developed and applied to hemp fibre woven fabrics/epoxy composite. The experimental program consists of tensile tests performed on single yarn, neat epoxy resin and composite materials to identify their AE amplitude signatures. A statistical analysis of AE amplitude signals has been realised and correlated with microscopic observations. Results have enabled to identify three types of damage in composites and their associated AE amplitudes: matrix cracking, interfacial debonding and reinforcement damage and fracture. Tracking of these damage mechanisms in hemp/epoxy composites has been performed to show the process of damage development in natural fibre reinforced composites.

  19. 3D-Printed Multidrug-Eluting Stent from Graphene-Nanoplatelet-Doped Biodegradable Polymer Composite.

    PubMed

    Misra, Santosh K; Ostadhossein, Fatemeh; Babu, Ramya; Kus, Joseph; Tankasala, Divya; Sutrisno, Andre; Walsh, Kathleen A; Bromfield, Corinne R; Pan, Dipanjan

    2017-03-21

    Patients with percutaneous coronary intervention generally receive either bare metal stents or drug-eluting stents to restore the normal blood flow. However, due to the lack of stent production with an individual patient in mind, the same level of effectiveness may not be possible in treating two different clinical scenarios. This study introduces for the first time the feasibility of a patient-specific stenting process constructed from direct 3D segmentation of medical images using direct 3D printing of biodegradable polymer-graphene composite with dual drug incorporation. A biodegradable polymer-carbon composite is prepared doped with graphene nanoplatelets to achieve controlled release of combinatorics as anticoagulation and antirestenosis agents. This study develops a technology prototyped for personalized stenting. An in silico analysis is performed to optimize the stent design for printing and its prediction of sustainability under force exerted by coronary artery or blood flow. A holistic approach covering in silico to in situ-in vivo establishes the structural integrity of the polymer composite, its mechanical properties, drug loading and release control, prototyping, functional activity, safety, and feasibility of placement in coronary artery of swine.

  20. Electromagnetic and absorbing property of CIPs/resin composite using the 3D forming process

    NASA Astrophysics Data System (ADS)

    Xu, Yonggang; Liang, Zichang; Wang, Xiaobing; Yuan, Liming; Li, Xinghao

    2016-08-01

    The absorbing composite filled with the flaky carbonyl iron particles (CIPs) were prepared using a three-dimensional (3D) forming process, in which the forming powder was fabricated using a milling process. The surface morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer, and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 4-18 GHz. With the variable thickness was set, the reflection loss (RL) was simulated to analyze the absorbing property of the composite. The results showed that the forming powder was uniformly dispersed in the absorber, and the saturation magnetization and the grain structure of the CIPs in the forming powder nearly did not change in the milling process. With the same volume content CIPs added, the average permittivity and the imaginary permeability of the samples added the powder was smaller than the directly mixing sample due to the aggregation effect. The RL results showed that the absorbing composites using the 3D forming process with thickness 6 or 8 mm had an better absorbing property (minimum RL -13.58 and -21.85 dB) in 4-18 GHz.

  1. Fatigue resistance of unnotched and post impact(+/- 30 deg/0 deg) 3-D braided composites

    NASA Technical Reports Server (NTRS)

    Portanova, Marc A.

    1994-01-01

    The fatigue resistance of a multiaxial braided (3-D) graphite/expoxy composite in both unnotched and post impacted conditions has been evaluated. The material tested is a (+/- 30/0 deg) multiaxial braid constructed from AS4/12K tow graphite fibers and British Petroleum E905L epoxy resin. These materials were braided as dry preforms and the epoxy was added using a resin transfer molding process (RTM). The unnotched and post-impact specimens were tested in compression-compression fatigue at 10 Hz with a stress ratio of R=10. The unnotched tension-tension fatigue specimens were tested at S Hz with a stress ration of R=0.1. Damage initiation and growth was documented through the application of radiography and ultrasonic through transmission (C-scans). Visible inspection of surface and edge damage was also noted to describe the initiation and progression of damage in these materials. The mechanisms leading to damage initiation were established and failure modes were determined. Stiffness and strength degradation were measured as a function of applied cycles. These 3-D braided composite results were compared to strain levels currently used to design primary structure in commercial aircraft composite components made from prepreg tape and autoclave cured.

  2. 3D printing of composite tissue with complex shape applied to ear regeneration.

    PubMed

    Lee, Jung-Seob; Hong, Jung Min; Jung, Jin Woo; Shim, Jin-Hyung; Oh, Jeong-Hoon; Cho, Dong-Woo

    2014-06-01

    In the ear reconstruction field, tissue engineering enabling the regeneration of the ear's own tissue has been considered to be a promising technology. However, the ear is known to be difficult to regenerate using traditional methods due to its complex shape and composition. In this study, we used three-dimensional (3D) printing technology including a sacrificial layer process to regenerate both the auricular cartilage and fat tissue. The main part was printed with poly-caprolactone (PCL) and cell-laden hydrogel. At the same time, poly-ethylene-glycol (PEG) was also deposited as a sacrificial layer to support the main structure. After complete fabrication, PEG can be easily removed in aqueous solutions, and the procedure for removing PEG has no effect on the cell viability. For fabricating composite tissue, chondrocytes and adipocytes differentiated from adipose-derived stromal cells were encapsulated in hydrogel to dispense into the cartilage and fat regions, respectively, of ear-shaped structures. Finally, we fabricated the composite structure for feasibility testing, satisfying expectations for both the geometry and anatomy of the native ear. We also carried out in vitro assays for evaluating the chondrogenesis and adipogenesis of the cell-printed structure. As a result, the possibility of ear regeneration using 3D printing technology which allowed tissue formation from the separately printed chondrocytes and adipocytes was demonstrated.

  3. Individual versus collective fibroblast spreading and migration: regulation by matrix composition in 3D culture.

    PubMed

    Miron-Mendoza, Miguel; Lin, Xihui; Ma, Lisha; Ririe, Peter; Petroll, W Matthew

    2012-06-01

    Extracellular matrix (ECM) supplies both physical and chemical signals to cells and provides a substrate through which fibroblasts migrate during wound repair. To directly assess how ECM composition regulates this process, we used a nested 3D matrix model in which cell-populated collagen buttons were embedded in cell-free collagen or fibrin matrices. Time-lapse microscopy was used to record the dynamic pattern of cell migration into the outer matrices, and 3D confocal imaging was used to assess cell connectivity and cytoskeletal organization. Corneal fibroblasts stimulated with PDGF migrated more rapidly into collagen as compared to fibrin. In addition, the pattern of fibroblast migration into fibrin and collagen ECMs was strikingly different. Corneal fibroblasts migrating into collagen matrices developed dendritic processes and moved independently, whereas cells migrating into fibrin matrices had a more fusiform morphology and formed an interconnected meshwork. A similar pattern was observed when using dermal fibroblasts, suggesting that this response is not unique to corneal cells. We next cultured corneal fibroblasts within and on top of standard collagen and fibrin matrices to assess the impact of ECM composition on the cell spreading response. Similar differences in cell morphology and connectivity were observed – cells remained separated on collagen but coalesced into clusters on fibrin. Cadherin was localized to junctions between interconnected cells, whereas fibronectin was present both between cells and at the tips of extending cell processes. Cells on fibrin matrices also developed more prominent stress fibers than those on collagen matrices. Importantly, these spreading and migration patterns were consistently observed on both rigid and compliant substrates, thus differences in ECM mechanical stiffness were not the underlying cause. Overall, these results demonstrate for the first time that ECM protein composition alone (collagen vs. fibrin) can induce

  4. 3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration.

    PubMed

    Inzana, Jason A; Olvera, Diana; Fuller, Seth M; Kelly, James P; Graeve, Olivia A; Schwarz, Edward M; Kates, Stephen L; Awad, Hani A

    2014-04-01

    Low temperature 3D printing of calcium phosphate scaffolds holds great promise for fabricating synthetic bone graft substitutes with enhanced performance over traditional techniques. Many design parameters, such as the binder solution properties, have yet to be optimized to ensure maximal biocompatibility and osteoconductivity with sufficient mechanical properties. This study tailored the phosphoric acid-based binder solution concentration to 8.75 wt% to maximize cytocompatibility and mechanical strength, with a supplementation of Tween 80 to improve printing. To further enhance the formulation, collagen was dissolved into the binder solution to fabricate collagen-calcium phosphate composites. Reducing the viscosity and surface tension through a physiologic heat treatment and Tween 80, respectively, enabled reliable thermal inkjet printing of the collagen solutions. Supplementing the binder solution with 1-2 wt% collagen significantly improved maximum flexural strength and cell viability. To assess the bone healing performance, we implanted 3D printed scaffolds into a critically sized murine femoral defect for 9 weeks. The implants were confirmed to be osteoconductive, with new bone growth incorporating the degrading scaffold materials. In conclusion, this study demonstrates optimization of material parameters for 3D printed calcium phosphate scaffolds and enhancement of material properties by volumetric collagen incorporation via inkjet printing.

  5. 3D Printing of Composite Calcium Phosphate and Collagen Scaffolds for Bone Regeneration

    PubMed Central

    Inzana, Jason A.; Olvera, Diana; Fuller, Seth M.; Kelly, James P.; Graeve, Olivia A.; Schwarz, Edward M.; Kates, Stephen L.; Awad, Hani A.

    2014-01-01

    Low temperature 3D printing of calcium phosphate scaffolds holds great promise for fabricating synthetic bone graft substitutes with enhanced performance over traditional techniques. Many design parameters, such as the binder solution properties, have yet to be optimized to ensure maximal biocompatibility and osteoconductivity with sufficient mechanical properties. This study tailored the phosphoric acid-based binder solution concentration to 8.75 wt% to maximize cytocompatibility and mechanical strength, with a supplementation of Tween 80 to improve printing. To further enhance the formulation, collagen was dissolved into the binder solution to fabricate collagen-calcium phosphate composites. Reducing the viscosity and surface tension through a physiologic heat treatment and Tween 80, respectively, enabled reliable thermal inkjet printing of the collagen solutions. Supplementing the binder solution with 1–2 wt% collagen significantly improved maximum flexural strength and cell viability. To assess the bone healing performance, we implanted 3D printed scaffolds into a critically sized murine femoral defect for 9 weeks. The implants were confirmed to be osteoconductive, with new bone growth incorporating the degrading scaffold materials. In conclusion, this study demonstrates optimization of material parameters for 3D printed calcium phosphate scaffolds and enhancement of material properties by volumetric collagen incorporation via inkjet printing. PMID:24529628

  6. Evaluation of a non-woven fabric coated with a chitosan bi-layer composite for wound dressing.

    PubMed

    Liu, Bai-Shuan; Yao, Chun-Hsu; Fang, Shr-Shin

    2008-05-13

    This study presents a novel design of an easily stripped bi-layer composite that consists of an upper layer of a soybean protein non-woven fabric coated with a lower layer, a genipin-crosslinked chitosan film, as a wound dressing material. This study examines the in vitro properties of the genipin-crosslinked chitosan film and the bi-layer composite. Furthermore, in vivo experiments are conducted to study wounds treated with the composite in a rat model. Experimental results show that the degree of crosslinking and the in vitro degradation rate of the genipin-crosslinked chitosan films can be controlled by varying the genipin contents. In addition, the genipin contents should exceed 0.025 wt.-% of the chitosan-based material if complete crosslinking reactions between genipin and chitosan molecules are required. Water contact angle analysis shows that the genipin-crosslinked chitosan film is not highly hydrophilic; therefore, the genipin-crosslinked chitosan layer is not entangled with the soybean protein non-woven fabric, which forms an easily stripped interface layer between them. Furthermore, this new wound dressing material provides adequate moisture, thereby minimizing the risk of wound dehydration, and exhibits good mechanical properties. The in vivo histological assessment results reveal that epithelialization and reconstruction of the wound are achieved by covering the wound with the composite, and the composite is easily stripped from the wound surface without damaging newly regenerated tissue.

  7. Fatigue damage characterization of braided and woven fiber reinforced polymer matrix composites at room and elevated temperatures

    NASA Astrophysics Data System (ADS)

    Montesano, John

    The use of polymer matrix composites (PMC) for manufacturing primary load-bearing structural components has significantly increased in many industrial applications. Specifically in the aerospace industry, PMCs are also being considered for elevated temperature applications. Current aerospace-grade composite components subjected to fatigue loading are over-designed due to insufficient understanding of the material failure processes, and due to the lack of available generic fatigue prediction models. A comprehensive literature survey reveals that there are few fatigue studies conducted on woven and braided fabric reinforced PMC materials, and even fewer at elevated temperatures. It is therefore the objective of this study to characterize and subsequently model the elevated temperature fatigue behaviour of a triaxial braided PMC, and to investigate the elevated temperature fatigue properties of two additional woven PMCs. An extensive experimental program is conducted using a unique test protocol on the braided and woven composites, which consists of static and fatigue testing at various test temperatures. The development of mechanically-induced damage is monitored using a combination of non-destructive techniques which included infrared thermography, fiber optic sensors and edge replication. The observed microscopic damage development is quantified and correlated to the exhibited macroscopic material behaviour at all test temperatures. The fiber-dominated PMC materials considered in this study did not exhibit notable time- or temperature-dependent static properties. However, fatigue tests reveal that the local damage development is in fact notably influenced by temperature. The elevated temperature environment increases the toughness of the thermosetting polymers, which results in consistently slower fatigue crack propagation rates for the respective composite materials. This has a direct impact on the stiffness degradation rate and the fatigue lives for the braided

  8. Failure Locus of 3D Four-Directional Braided Composites Under Biaxial Loading

    NASA Astrophysics Data System (ADS)

    Wang, Baolai; Fang, Guodong; Liang, Jun; Wang, Zhenqing

    2012-06-01

    The failure locus of 3D braided four-directional composites under complex loadings, such as tension-shear, compression-shear and tension-tension, can be obtained by micromechanical computation model. A finite element model of representative volume cell (RVC) of the braided composites, explicitly taking into account the braid yarn and matrix, is chosen to analyze the mechanical response. The failure mechanisms of the braided composites observed in experiment can be reproduced by the numerical computation in which the mesoscopic damage models of the braid yarn and matrix are developed. Several failure points of the braided composites under the biaxial loadings can be obtained when different stress ratios are imposed upon the RVC. In comparison with the Tsai-Wu and Tsai-Hahn criteria, the numerical failure loci of the braided composites except the tension-tension results are in good agreement with those results. It can be pointed out that the failure loci of the braided composites can be obtained by the numerical fitting of a large number of the failure points which are calculated by the numerical model.

  9. Development of Stitched, Braided and Woven Composite Structures in the ACT Program and at Langley Research Center

    NASA Technical Reports Server (NTRS)

    Dow, Marvin B.; Dexter, H. Benson

    1997-01-01

    Summary results are presented from the research conducted on woven, braided, knitted and stitched (textile) composites at the Langley Research Center and under the NASA Advanced Composites Technology (ACT) Program in the period from 1985 to 1997. The report also includes an annotated bibliography of 270 U.S. publications on textile composites (with their abstracts). Two major research areas are discussed: (1) the general research in textile composites performed throughout the period under the direction of the Langley Research Center and (2) the development of textile composite aircraft structures by industry under the NASA ACT Program. The annotated bibliography is organized in three subsections: (1) general textiles R&D under the auspices of Langley, (2) ACT Program development of textile structural components, and (3) textiles research by individuals and organizations not associated with the ACT Program. An author index is provided for the reports and documents.

  10. Spatial Distribution of Yarns and Mechanical Properties in 3D Braided Tubular Composites

    NASA Astrophysics Data System (ADS)

    Wang, Y. Q.; Wang, A. S. D.

    1997-03-01

    This paper outlines a method which links the following analytically simulated events in sequence: (1) braiding of a 3D preform of tubular cross-section characterized by a set of braiding parameters defining the braiding setup and braiding steps; (2) geometric description of the yarn topology in the braided preform in explicit terms of a set of topological parameters defined by the preform shape and the braiding parameters; (3) description of the exact yarn distribution after preform consolidation with a binding matrix the values of the topological parameters are related to the exterior dimensions and surface features of the consolidated preform; and (4) forecasting the mechanical properties in the final composite via a suitable micromechanics model that takes into account the spatial yarn distribution in the composite and properties of the constituents.

  11. Higher Order Finite Element Methods for Compositional Simulation in 3D Multiphase Multicomponent Flow

    NASA Astrophysics Data System (ADS)

    Shahraeeni, E.; Firoozabadi, A.

    2012-12-01

    We present a 3D model for fully compositional multi-phase multi-component flow in porous media with species transfer between the phases. Phase properties are modeled with the Peng-Robinson equation of state. Because phase properties may exhibit strong discontinuities, we approximate the mass transport update by the means of discontinuous Galerkin method. Pressure and velocity fields are continuous across the whole domain of solution, which is guaranteed by using the mixed hybrid finite element method. Complexity of the flow necessitates the use of either very fine mesh or higher-order schemes. The use of higher-order finite element methods significantly reduces numerical dispersion and grid orientation effects that plague traditional finite difference methods. We have shown that in 3D the convergence rate of our scheme is twice as first order method and the CPU time may improve up to three orders of magnitude for the same level of accuracy. Our numerical model facilitates accurate simulation of delicate feature of compositional flow like fingering and CO2 injection in complex reservoirs for a broad range of applications, including CO2 sequestration in finite aquifer and water flooded reservoirs with transfer of all species between the phases.

  12. A Micromechanical Unit Cell Model of 2 × 2 Twill Woven Fabric Textile Composite for Multi Scale Analysis

    NASA Astrophysics Data System (ADS)

    Dixit, A.; Mali, H. S.; Misra, R. K.

    2014-04-01

    Woven fabric based composite materials are being considered for potential structural applications in automotive and aircraft industries due to their better out of plane strength, stiffness and toughness properties than ordinary composite laminates. This paper presents the micromechanical unit cell model of 2 × 2 twill woven fabric textile composite for the estimation of in-plane elastic properties. Modelling of unit cell and its analysis for this new model is developed by using open source coded tool TexGen and finite element software, ABAQUS® respectively. The predicted values are in good agreement with the experimental results reported in literature. To ascertain the effectiveness of the developed model parametric studies have also been conducted on the predicted elastic properties in order to investigate the effects of various geometric parameters such as yarn spacing, fabric thickness, yarn width and fibre volume fraction. The scope of altering weave pattern and yarn characteristics is facilitated in this developed model. Further this model can be implemented for the multi-scale micro/macro-mechanical analysis for the calculation of strength and stiffness of laminates structure made of 2 × 2 twill composite.

  13. 3D Simulation of the Growth of Alloy Semiconductor Quantum Dots Considering Morphological and Compositional Coupling

    NASA Astrophysics Data System (ADS)

    Guo, Junyan; Zhang, Yong-Wei; Narayanaswamy, Sridhar

    2012-02-01

    Fabrication of quantum dots (QDs) with high density may be realized by self-assembly via heteroepitaxial growth of thin films. Since the electronic and optoelectronic properties of QDs are sensitive to size, morphology, strain and especially composition, it is of great importance to control their composition profiles and morphology, and engineer the strain in them. Since the growth is a dynamic process, which carries out via surface diffusion driven primarily by strain relaxation and entropy change due to chemical intermixing, a strong coupling between morphological and composition evolutions during this process leads to a rather complex dynamics, which has not been fully understood. In this work, a 3-D finite element model is developed, which is capable of modeling the formation, self-assembly and coarsening of hetero-epitaxial alloy islands by considering the coupling of morphological and compositional evolution. Several interesting experimental observations, such as fast coarsening kinetics; asymmetries in composition profile and island shape; lateral motion of alloy islands have been observed in our simulations. Our model predictions have painted a rather complete picture for the entire dynamic evolution during the growth of nanoscale heteroepitaxial islands.

  14. Combining 3D optical imaging and dual energy absorptiometry to measure three compositional components.

    PubMed

    Malkov, Serghei; Shepherd, John

    2014-02-17

    We report on the design of the technique combining 3D optical imaging and dual-energy absorptiometry body scanning to estimate local body area compositions of three compartments. Dual-energy attenuation and body shape measures are used together to solve for the three compositional tissue thicknesses: water, lipid, and protein. We designed phantoms with tissue-like properties as our reference standards for calibration purposes. The calibration was created by fitting phantom values using non-linear regression of quadratic and truncated polynomials. Dual-energy measurements were performed on tissue-mimicking phantoms using a bone densitometer unit. The phantoms were made of materials shown to have similar x-ray attenuation properties of the biological compositional compartments. The components for the solid phantom were tested and their high energy/low energy attenuation ratios are in good correspondent to water, lipid, and protein for the densitometer x-ray region. The three-dimensional body shape was reconstructed from the depth maps generated by Microsoft Kinect for Windows. We used open-source Point Cloud Library and freeware software to produce dense point clouds. Accuracy and precision of compositional and thickness measures were calculated. The error contributions due to two modalities were estimated. The preliminary phantom composition and shape measurements are found to demonstrate the feasibility of the method proposed.

  15. Combining 3D optical imaging and dual energy absorptiometry to measure three compositional components

    PubMed Central

    Malkov, Serghei; Shepherd, John

    2014-01-01

    We report on the design of the technique combining 3D optical imaging and dual-energy absorptiometry body scanning to estimate local body area compositions of three compartments. Dual-energy attenuation and body shape measures are used together to solve for the three compositional tissue thicknesses: water, lipid, and protein. We designed phantoms with tissue-like properties as our reference standards for calibration purposes. The calibration was created by fitting phantom values using non-linear regression of quadratic and truncated polynomials. Dual-energy measurements were performed on tissue-mimicking phantoms using a bone densitometer unit. The phantoms were made of materials shown to have similar x-ray attenuation properties of the biological compositional compartments. The components for the solid phantom were tested and their high energy/low energy attenuation ratios are in good correspondent to water, lipid, and protein for the densitometer x-ray region. The three-dimensional body shape was reconstructed from the depth maps generated by Microsoft Kinect for Windows. We used open-source Point Cloud Library and freeware software to produce dense point clouds. Accuracy and precision of compositional and thickness measures were calculated. The error contributions due to two modalities were estimated. The preliminary phantom composition and shape measurements are found to demonstrate the feasibility of the method proposed. PMID:25083118

  16. Combining 3D optical imaging and dual energy absorptiometry to measure three compositional components

    NASA Astrophysics Data System (ADS)

    Malkov, Serghei; Shepherd, John

    2014-02-01

    We report on the design of the technique combining 3D optical imaging and dual-energy absorptiometry body scanning to estimate local body area compositions of three compartments. Dual-energy attenuation and body shape measures are used together to solve for the three compositional tissue thicknesses: water, lipid, and protein. We designed phantoms with tissue-like properties as our reference standards for calibration purposes. The calibration was created by fitting phantom values using non-linear regression of quadratic and truncated polynomials. Dual-energy measurements were performed on tissue-mimicking phantoms using a bone densitometer unit. The phantoms were made of materials shown to have similar x-ray attenuation properties of the biological compositional compartments. The components for the solid phantom were tested and their high energy/low energy attenuation ratios are in good correspondent to water, lipid, and protein for the densitometer x-ray region. The three-dimensional body shape was reconstructed from the depth maps generated by Microsoft Kinect for Windows. We used open-source Point Cloud Library and freeware software to produce dense point clouds. Accuracy and precision of compositional and thickness measures were calculated. The error contributions due to two modalities were estimated. The preliminary phantom composition and shape measurements are found to demonstrate the feasibility of the method proposed.

  17. Numerical Investigation of T-joints with 3D Four Directional Braided Composite Fillers Under Tensile Loading

    NASA Astrophysics Data System (ADS)

    Li, Xiao-kang; Liu, Zhen-guo; Hu, Long; Wang, Yi-bo; Lei, Bing; Huang, Xiang

    2017-02-01

    Numerical studied on T-joints with three-dimensional four directional (3D4D) braided composite fillers was presented in this article. Compared with conventional unidirectional prepreg fillers, the 3D braided composite fillers have excellent ability to prevent crack from penetrating trigone fillers, which constantly occurred in the conventional fillers. Meanwhile, the 3D braided composite fillers had higher fiber volume fraction and eliminated the fiber folding problem in unidirectional prepreg fillers. The braiding technology and mechanical performance of 3D4D braided fillers were studied. The numerical model of carbon fiber T-joints with 3D4D braided composite fillers was built by finite element analysis software. The damage formation, extension and failing process of T-joints with 3D4D braided fillers under tensile load were investigated. Further investigation was extended to the effect of 3D4D braided fillers with different braiding angles on mechanical behavior of the T-joints. The study results revealed that the filling area was the weakest part of the T-joints where the damage first appeared and the crack then rapidly spread to the glue film around the filling area and the interface between over-laminate and soleplate. The 3D4D braided fillers were undamaged and the braiding angle change induced a little effect on the bearing capacity of T-joints.

  18. A High-Resolution 3D Weather Radar, MSG, and Lightning Sensor Observation Composite

    NASA Astrophysics Data System (ADS)

    Diederich, Malte; Senf, Fabian; Wapler, Kathrin; Simmer, Clemens

    2013-04-01

    Within the research group 'Object-based Analysis and SEamless prediction' (OASE) of the Hans Ertel Centre for Weather Research programme (HerZ), a data composite containing weather radar, lightning sensor, and Meteosat Second Generation observations is being developed for the use in object-based weather analysis and nowcasting. At present, a 3D merging scheme combines measurements of the Bonn and Jülich dual polarimetric weather radar systems (data provided by the TR32 and TERENO projects) into a 3-dimensional polar-stereographic volume grid, with 500 meters horizontal, and 250 meters vertical resolution. The merging takes into account and compensates for various observational error sources, such as attenuation through hydrometeors, beam blockage through topography and buildings, minimum detectable signal as a function of noise threshold, non-hydrometeor echos like insects, and interference from other radar systems. In addition to this, the effect of convection during the radar 5-minute volume scan pattern is mitigated through calculation of advection vectors from subsequent scans and their use for advection correction when projecting the measurements into space for any desired timestamp. The Meteosat Second Generation rapid scan service provides a scan in 12 spectral visual and infrared wavelengths every 5 minutes over Germany and Europe. These scans, together with the derived microphysical cloud parameters, are projected into the same polar stereographic grid used for the radar data. Lightning counts from the LINET lightning sensor network are also provided for every 2D grid pixel. The combined 3D radar and 2D MSG/LINET data is stored in a fully documented netCDF file for every 5 minute interval, and is made ready for tracking and object based weather analysis. At the moment, the 3D data only covers the Bonn and Jülich area, but the algorithms are planed to be adapted to the newly conceived DWD polarimetric C-Band 5 minute interval volume scan strategy. An

  19. A Shell/3D Modeling Technique for the Analyses of Delaminated Composite Laminates

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; OBrien, T. Kevin

    2001-01-01

    A shell/3D modeling technique was developed for which a local three-dimensional solid finite element model is used only in the immediate vicinity of the delamination front. The goal was to combine the accuracy of the full three-dimensional solution with the computational efficiency of a plate or shell finite element model. Multi-point constraints provided a kinematically compatible interface between the local three-dimensional model and the global structural model which has been meshed with plate or shell finite elements. Double Cantilever Beam (DCB), End Notched Flexure (ENF), and Single Leg Bending (SLB) specimens were modeled using the shell/3D technique to study the feasibility for pure mode I (DCB), mode II (ENF) and mixed mode I/II (SLB) cases. Mixed mode strain energy release rate distributions were computed across the width of the specimens using the virtual crack closure technique. Specimens with a unidirectional layup and with a multidirectional layup where the delamination is located between two non-zero degree plies were simulated. For a local three-dimensional model, extending to a minimum of about three specimen thicknesses on either side of the delamination front, the results were in good agreement with mixed mode strain energy release rates obtained from computations where the entire specimen had been modeled with solid elements. For large built-up composite structures modeled with plate elements, the shell/3D modeling technique offers a great potential for reducing the model size, since only a relatively small section in the vicinity of the delamination front needs to be modeled with solid elements.

  20. Analysis of Composite Panel-Stiffener Debonding Using a Shell/3D Modeling Technique

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; Ratcliffe, James; Minguet, Pierre J.

    2007-01-01

    Interlaminar fracture mechanics has proven useful for characterizing the onset of delaminations in composites and has been used successfully primarily to investigate onset in fracture toughness specimens and laboratory size coupon type specimens. Future acceptance of the methodology by industry and certification authorities, however, requires the successful demonstration of the methodology on the structural level. For this purpose, a panel was selected that is reinforced with stiffeners. Shear loading causes the panel to buckle, and the resulting out-of-plane deformations initiate skin/stiffener separation at the location of an embedded defect. A small section of the stiffener foot, web and noodle as well as the panel skin in the vicinity of the delamination front were modeled with a local 3D solid model. Across the width of the stiffener foot, the mixedmode strain energy release rates were calculated using the virtual crack closure technique. A failure index was calculated by correlating the results with a mixed-mode failure criterion of the graphite/epoxy material. Computed failure indices were compared to corresponding results where the entire web was modeled with shell elements and only a small section of the stiffener foot and panel were modeled locally with solid elements. Including the stiffener web in the local 3D solid model increased the computed failure index. Further including the noodle and transition radius in the local 3D solid model changed the local distribution across the width. The magnitude of the failure index decreased with increasing transition radius and noodle area. For the transition radii modeled, the material properties used for the noodle area had a negligible effect on the results. The results of this study are intended to be used as a guide for conducting finite element and fracture mechanics analyses of delamination and debonding in complex structures such as integrally stiffened panels.

  1. Correlative Nanoscale 3D Imaging of Structure and Composition in Extended Objects

    PubMed Central

    Xu, Feng; Helfen, Lukas; Suhonen, Heikki; Elgrabli, Dan; Bayat, Sam; Reischig, Péter; Baumbach, Tilo; Cloetens, Peter

    2012-01-01

    Structure and composition at the nanoscale determine the behavior of biological systems and engineered materials. The drive to understand and control this behavior has placed strong demands on developing methods for high resolution imaging. In general, the improvement of three-dimensional (3D) resolution is accomplished by tightening constraints: reduced manageable specimen sizes, decreasing analyzable volumes, degrading contrasts, and increasing sample preparation efforts. Aiming to overcome these limitations, we present a non-destructive and multiple-contrast imaging technique, using principles of X-ray laminography, thus generalizing tomography towards laterally extended objects. We retain advantages that are usually restricted to 2D microscopic imaging, such as scanning of large areas and subsequent zooming-in towards a region of interest at the highest possible resolution. Our technique permits correlating the 3D structure and the elemental distribution yielding a high sensitivity to variations of the electron density via coherent imaging and to local trace element quantification through X-ray fluorescence. We demonstrate the method by imaging a lithographic nanostructure and an aluminum alloy. Analyzing a biological system, we visualize in lung tissue the subcellular response to toxic stress after exposure to nanotubes. We show that most of the nanotubes are trapped inside alveolar macrophages, while a small portion of the nanotubes has crossed the barrier to the cellular space of the alveolar wall. In general, our method is non-destructive and can be combined with different sample environmental or loading conditions. We therefore anticipate that correlative X-ray nano-laminography will enable a variety of in situ and in operando 3D studies. PMID:23185554

  2. Finite Element Analysis of Warp-Reinforced 2.5D Woven Composites Based on a Meso-Scale Voxel Model under Compression Loading

    NASA Astrophysics Data System (ADS)

    Zhang, Diantang; Chen, Li; Wang, Yanjie; Sun, Ying; Jia, Na; Qian, Kun

    2016-11-01

    A study is conducted with the aim of developing meso-scale voxel-based model for evaluating the compressive behaviors of warp-reinforced 2.5D woven composites. The real microstructure of warp-reinforced 2.5D woven composites is established. For the validation of this model, a series of axial (warp direction) and transverse (weft direction) compressive tests are conducted. The results show that under axial and transverse compressive loading, the calculated max stress and the final damage morphology agree well with the experimental results. Moreover, it is found that the axial compressive strength is mainly dependent on the high-crimp blinder warp, while the transverse compressive strength is significantly influenced by the warp/weft interlaced regions. It is expected that such a numerical investigation will provide useful information for understanding the strength and failure characteristic of 2.5D woven composites.

  3. Smart three-dimensional lightweight structure triggered from a thin composite sheet via 3D printing technique

    PubMed Central

    Zhang, Quan; Zhang, Kai; Hu, Gengkai

    2016-01-01

    Complex fabrication process and expensive materials have restricted the development of smart three-dimensional (3D) lightweight structures, which are expected to possess self-shaping, self-folding and self-unfolding performances. Here we present a simple approach to fabricate smart lightweight structures by triggering shape transformation from thin printed composite sheets. The release of the internal strain in printed polymer materials enables the printed composite sheet to keep flat under heating and transform into a designed 3D configuration when cooled down to room temperature. The 3D lightweight structure can be switched between flat and 3D configuration under appropriate thermal stimuli. Our work exploits uniform internal strain in printed materials as a controllable tool to fabricate smart 3D lightweight structures, opening an avenue for possible applications in engineering fields. PMID:26926357

  4. Smart three-dimensional lightweight structure triggered from a thin composite sheet via 3D printing technique

    NASA Astrophysics Data System (ADS)

    Zhang, Quan; Zhang, Kai; Hu, Gengkai

    2016-02-01

    Complex fabrication process and expensive materials have restricted the development of smart three-dimensional (3D) lightweight structures, which are expected to possess self-shaping, self-folding and self-unfolding performances. Here we present a simple approach to fabricate smart lightweight structures by triggering shape transformation from thin printed composite sheets. The release of the internal strain in printed polymer materials enables the printed composite sheet to keep flat under heating and transform into a designed 3D configuration when cooled down to room temperature. The 3D lightweight structure can be switched between flat and 3D configuration under appropriate thermal stimuli. Our work exploits uniform internal strain in printed materials as a controllable tool to fabricate smart 3D lightweight structures, opening an avenue for possible applications in engineering fields.

  5. Smart three-dimensional lightweight structure triggered from a thin composite sheet via 3D printing technique.

    PubMed

    Zhang, Quan; Zhang, Kai; Hu, Gengkai

    2016-02-29

    Complex fabrication process and expensive materials have restricted the development of smart three-dimensional (3D) lightweight structures, which are expected to possess self-shaping, self-folding and self-unfolding performances. Here we present a simple approach to fabricate smart lightweight structures by triggering shape transformation from thin printed composite sheets. The release of the internal strain in printed polymer materials enables the printed composite sheet to keep flat under heating and transform into a designed 3D configuration when cooled down to room temperature. The 3D lightweight structure can be switched between flat and 3D configuration under appropriate thermal stimuli. Our work exploits uniform internal strain in printed materials as a controllable tool to fabricate smart 3D lightweight structures, opening an avenue for possible applications in engineering fields.

  6. Strengthening of 3D Printed Fused Deposition Manufactured Parts Using the Fill Compositing Technique

    PubMed Central

    Belter, Joseph T.; Dollar, Aaron M.

    2015-01-01

    In this paper, we present a technique for increasing the strength of thermoplastic fused deposition manufactured printed parts while retaining the benefits of the process such as ease, speed of implementation, and complex part geometries. By carefully placing voids in the printed parts and filling them with high-strength resins, we can improve the overall part strength and stiffness by up to 45% and 25%, respectively. We discuss the process parameters necessary to use this strengthening technique and the theoretically possible strength improvements to bending beam members. We then show three-point bend testing data comparing solid printed ABS samples with those strengthened through the fill compositing process, as well as examples of 3D printed parts used in real-world applications. PMID:25880807

  7. Towards automated 3D finite element modeling of direct fiber reinforced composite dental bridge.

    PubMed

    Li, Wei; Swain, Michael V; Li, Qing; Steven, Grant P

    2005-07-01

    An automated 3D finite element (FE) modeling procedure for direct fiber reinforced dental bridge is established on the basis of computer tomography (CT) scan data. The model presented herein represents a two-unit anterior cantilever bridge that includes a maxillary right incisor as an abutment and a maxillary left incisor as a cantilever pontic bonded by adhesive and reinforced fibers. The study aims at gathering fundamental knowledge for design optimization of this type of innovative composite dental bridges. To promote the automatic level of numerical analysis and computational design of new dental biomaterials, this report pays particular attention to the mathematical modeling, mesh generation, and validation of numerical models. To assess the numerical accuracy and to validate the model established, a convergence test and experimental verification are also presented.

  8. Strengthening of 3D printed fused deposition manufactured parts using the fill compositing technique.

    PubMed

    Belter, Joseph T; Dollar, Aaron M

    2015-01-01

    In this paper, we present a technique for increasing the strength of thermoplastic fused deposition manufactured printed parts while retaining the benefits of the process such as ease, speed of implementation, and complex part geometries. By carefully placing voids in the printed parts and filling them with high-strength resins, we can improve the overall part strength and stiffness by up to 45% and 25%, respectively. We discuss the process parameters necessary to use this strengthening technique and the theoretically possible strength improvements to bending beam members. We then show three-point bend testing data comparing solid printed ABS samples with those strengthened through the fill compositing process, as well as examples of 3D printed parts used in real-world applications.

  9. Analysis of Composite Panel-Stiffener Debonding Using a Shell/3D Modeling Technique

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; Minguet, Pierre J.

    2006-01-01

    Interlaminar fracture mechanics has proven useful for characterizing the onset of delaminations in composites and has been used with limited success primarily to investigate onset in fracture toughness specimens and laboratory size coupon type specimens. Future acceptance of the methodology by industry and certification authorities however, requires the successful demonstration of the methodology on structural level. For this purpose a panel was selected that was reinforced with stringers. Shear loading cases the panel to buckle and the resulting out-of-plane deformations initiate skin/stringer separation at the location of an embedded defect. For finite element analysis, the panel and surrounding load fixture were modeled with shell element. A small section of the stringer foot and the panel in the vicinity of the embedded defect were modeled with a local 3D solid model. A failure index was calculated by correlating computed mixed-mode failure criterion of the graphite/epoxy material.

  10. Advanced 3D textile composites reinforcements meso F.E analyses based on X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Naouar, Naim; Vidal-Salle, Emmanuelle; Boisse, Philippe

    2016-10-01

    Meso-FE modelling of 3D textile composites is a powerful tool, which can help determine mechanical properties and permeability of the reinforcements or composites. The quality of the meso FE analyses depends on the quality of the initial model. A direct method based on X-ray tomography imaging is introduced to determine finite element models based on the real geometry of 3D composite reinforcements. The method is particularly suitable regarding 3D textile reinforcements for which internal geometries are numerous and complex. The approach used for the separation of the yarns in different directions is specialized because the fibres flow in three-dimensional space. An analysis of the image's texture is performed. A hyperelastic model developed for fibre bundles is used for the simulation of the deformation of the 3D reinforcement.

  11. Study of strength properties of ceramic composites with soft filler based on 3D computer simulation

    NASA Astrophysics Data System (ADS)

    Smolin, Alexey Yu.; Smolin, Igor Yu.; Smolina, Irina Yu.

    2016-11-01

    The movable cellular automaton method which is a computational method of particle mechanics is applied to simulating uniaxial compression of 3D specimens of a ceramic composite. Soft inclusions were considered explicitly by changing the sort (properties) of automata selected randomly from the original fcc packing. The distribution of inclusions in space, their size, and the total fraction were varied. For each value of inclusion fraction, there were generated several representative specimens with individual pore position in space. The resulting magnitudes of the elastic modulus and strength of the specimens were scattered and well described by the Weibull distribution. We showed that to reveal the dependence of the elastic and strength properties of the composite on the inclusion fraction it is much better to consider the mathematical expectation of the corresponding Weibull distribution, rather than the average of the values for the specimens of the same inclusion fraction. It is shown that the relation between the mechanical properties of material and its inclusion fraction depends significantly on the material structure. Namely, percolation transition from isolated inclusions to interconnected clusters of inclusions strongly manifests itself in the dependence of strength on the fraction of inclusions. Thus, the curve of strength versus inclusion fraction fits different equations for a different kind of structure.

  12. Multi-contrast 3D X-ray imaging of porous and composite materials

    SciTech Connect

    Sarapata, Adrian; Herzen, Julia; Ruiz-Yaniz, Maite; Zanette, Irene; Rack, Alexander; Pfeiffer, Franz

    2015-04-13

    Grating-based X-ray computed tomography allows for simultaneous and nondestructive determination of the full X-ray complex index of refraction and the scattering coefficient distribution inside an object in three dimensions. Its multi-contrast capabilities combined with a high resolution of a few micrometers make it a suitable tool for assessing multiple phases inside porous and composite materials such as concrete. Here, we present quantitative results of a proof-of-principle experiment performed on a concrete sample. Thanks to the complementarity of the contrast channels, more concrete phases could be distinguished than in conventional attenuation-based imaging. The phase-contrast reconstruction shows high contrast between the hardened cement paste and the aggregates and thus allows easy 3D segmentation. Thanks to the dark-field image, micro-cracks inside the coarse aggregates are visible. We believe that these results are extremely interesting in the field of porous and composite materials studies because of unique information provided by grating interferometry in a non-destructive way.

  13. Precise 3D printing of micro/nanostructures using highly conductive carbon nanotube-thiol-acrylate composites

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Xiong, W.; Jiang, L. J.; Zhou, Y. S.; Lu, Y. F.

    2016-04-01

    Two-photon polymerization (TPP) is of increasing interest due to its unique combination of truly three-dimensional (3D) fabrication capability and ultrahigh spatial resolution of ~40 nm. However, the stringent requirements of non-linear resins seriously limit the material functionality of 3D printing via TPP. Precise fabrication of 3D micro/nanostructures with multi-functionalities such as high electrical conductivity and mechanical strength is still a long-standing challenge. In this work, TPP fabrication of arbitrary 3D micro/nanostructures using multi-walled carbon nanotube (MWNT)-thiolacrylate (MTA) composite resins has been developed. Up to 0.2 wt% MWNTs have been incorporated into thiol-acrylate resins to form highly stable and uniform composite photoresists without obvious degradation for one week at room temperature. Various functional 3D micro/nanostructures including woodpiles, micro-coils, spiral-like photonic crystals, suspended micro-bridges, micro-gears and complex micro-cars have been successfully fabricated. The MTA composite resin offers significant enhancements in electrical conductivity and mechanical strength, and on the same time, preserving high optical transmittance and flexibility. Tightly controlled alignment of MWNTs and the strong anisotropy effect were confirmed. Microelectronic devices including capacitors and resistors made of the MTA composite polymer were demonstrated. The 3D micro/nanofabrication using the MTA composite resins enables the precise 3D printing of micro/nanostructures of high electrical conductivity and mechanical strength, which is expected to lead a wide range of device applications, including micro/nano-electromechanical systems (MEMS/NEMS), integrated photonics and 3D electronics.

  14. A facile one-step process for 3D N-doped noncovalent functionalization PS/rGO composites

    NASA Astrophysics Data System (ADS)

    Huang, Weiqi; Wang, Hua; Su, Zheng; Tian, Konghu; Ye, Xianzhu; Bao, Chao; Guo, Yulan; He, Jing; Tian, Xingyou

    2017-03-01

    This work reports a simple, versatile and facile one-step process to prepare the three-dimensional (3D) N-doped noncovalent functionalization polystyrene/reduced graphene oxide (PS/rGO) composites. In this, N, N-dimethylformamide (DMF) acts as the solvent, reducing agent, and more importantly, the N-doping agent. Various measurements have been carried out to characterize the structure and morphology of PS/rGO composites, in particular for the excellent electrical conductivity of PS/rGO composites compared with virgin PS, which was attributed to the 3D pores structure and the N-doping. With regards to the unique properties of graphene, the 3D framework structure and the N-doping, this composite material has great potential properties such as electro-magnetic interference shielding effectiveness (EMI) to be explored.

  15. Evaluation of micro-damage accumulation in holed plain-woven CFRP composite under fatigue loading

    NASA Astrophysics Data System (ADS)

    Ying, Jia; Nishikawa, Masaaki; Hojo, Masaki

    2014-03-01

    Fluorescence method was used to detect the micro-damage caused by fatigue in a plain-woven carbon fiber reinforced polymer (CFRP). Fluorescence measurement is a method which estimates micro-damage by measuring fluorescent intensity change inside materials. The principle is, larger micro-damage means larger plastic strain, thus more space in that damaged spot which allows more fluorescent dyes coming in the material. By detecting fluorescent intensity in CFRP layer by layer using confocal laser microscopy, micro-damage can be estimated. Results show that there's a good relationship between micro-damage and fluorescent intensity gradient.

  16. Low-velocity impact behavior of woven jute/poly(lactic acid) composites

    NASA Astrophysics Data System (ADS)

    Russo, Pietro; Simeoli, Giorgio; Papa, Ilaria; Acierno, Domenico; Lopresto, Valentina; Langella, Antonio

    2016-05-01

    Biocomposite laminates based on poly(lactic acid) (PLA) and woven jute fabric were obtained by film stacking and compression molding techniques. Sample laminates were systematically characterized by impact tests with a falling dart at impact energies equal to 5, 10 and 20 J. Tests showed that, investigated PLA/jute fabric plates suffer only barely visible damages at the first two levels of impact energy while they result to be perforated at 20 J as highlighted by photographic images taken on low and back side of impacted surfaces.

  17. Production Principles and Technological Development of Novel Woven Spacer Preforms and Integrated Stiffener Structures

    NASA Astrophysics Data System (ADS)

    Torun, Ahmet R.; Mountasir, Adil; Hoffmann, Gerald; Cherif, Chokri

    2013-06-01

    3D textile preforms offer a high potential to increase mechanical properties of composites and/or decrease manufacturing costs. Within the scope of this study, production principles were developed for complex spacer preforms and integrated stiffeners. These principles were applied through technological further development of the well-known face-to-face and terry weaving techniques. Various woven preforms were produced with Glass fibre/Polypropylene (GF/PP) Commingled yarns, however, the technology is suitable for any type of reinforcement yarns. U-shaped woven spacer preform was consolidated into a sandwich composite component for lightweight applications.

  18. Constituent Effects on the Stress-Strain Behavior of Woven Melt-Infiltrated SiC Composites

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Eldridge, Jeff I.; Levine, Stanley (Technical Monitor)

    2001-01-01

    The stress-strain behavior of 2D woven SiC fiber reinforced, melt-infiltrated SiC matrix composites with BN interphases were studied for composites fabricated with different fiber tow ends per unit length, different composite thickness, and different numbers of plies. In general, the stress-strain behavior, i.e., the 'knee' in the curve and the final slope of the stress-strain curve, was controlled by the volume fraction of fibers. Some of the composites exhibited debonding and sliding in between the interphase and the matrix rather than the more common debonding and sliding interface between the fiber and the interphase. Composites that exhibited this 'outside debonding' interface, in general, had lower elastic moduli and higher ultimate strains as well as longer pull-out lengths compared to the 'inside debonding' interface composites. Stress-strain curves were modeled where matrix crack formation as a function of stress was approximated from the acoustic emission activity and the measured crack density from the failed specimens. Interfacial shear strength measurements from individual fiber push-in tests were in good agreement with the interfacial shear strength values used to model the stress-strain curves.

  19. 3D composites based on the blends of chitosan and collagen with the addition of hyaluronic acid.

    PubMed

    Sionkowska, Alina; Kaczmarek, Beata; Lewandowska, Katarzyna; Grabska, Sylwia; Pokrywczyńska, Marta; Kloskowski, Tomasz; Drewa, Tomasz

    2016-08-01

    3D porous composites based on blends of chitosan, collagen and hyaluronic acid were obtained through the lyophilization process. Mechanical properties, swelling behavior and thermal stability of the blends were studied. Moreover, SEM images were taken and the structure of the blends was studied. Biological properties of the materials obtained were investigated by analyzing of proliferation rate of fibroblast cells incubated with biomaterial extract using MTT assay (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide). The results showed that the properties of 3D composites based on the blends of chitosan and collagen were altered after the addition 1%, 2% and 5% of hyaluronic acid. Mechanical properties and thermal stability of chitosan/collagen blends were improved in the presence of hyaluronic acid in the composite. New 3D materials based on the blends of chitosan, collagen and hyaluronic acid were non-toxic and did not significantly affect cell morphology.

  20. Visualizing nanoscale 3D compositional fluctuation of lithium in advanced lithium-ion battery cathodes

    SciTech Connect

    Devaraj, Arun; Gu, Meng; Colby, Robert J.; Yan, Pengfei; Wang, Chong M.; Zheng, Jianming; Xiao, Jie; Genc, Arda; Zhang, Jiguang; Belharouak, Ilias; Wang, Dapeng; Amine, Khalil; Thevuthasan, Suntharampillai

    2015-08-14

    The distribution and concentration of lithium in Li-ion battery cathodes at different stages of cycling is a pivotal factor in determining battery performance. Non-uniform distribution of the transition metal cations has been shown to affect cathode performance; however, the Li is notoriously challenging to characterize with typical high-spatial-resolution imaging techniques. Here, for the first time, laser–assisted atom probe tomography is applied to two advanced Li-ion battery oxide cathode materials—layered Li1.2Ni0.2Mn0.6O2 and spinel LiNi0.5Mn1.5O4—to unambiguously map the three dimensional (3D) distribution of Li at sub-nanometer spatial resolution and correlate it with the distribution of the transition metal cations (M) and the oxygen. The as-fabricated layered Li1.2Ni0.2Mn0.6O2 is shown to have Li-rich Li2MO3 phase regions and Li-depleted Li(Ni0.5Mn0.5)O2 regions while in the cycled layered Li1.2Ni0.2Mn0.6O2 an overall loss of Li and presence of Ni rich regions, Mn rich regions and Li rich regions are shown in addition to providing the first direct evidence for Li loss on cycling of layered LNMO cathodes. The spinel LiNi0.5Mn1.5O4 cathode is shown to have a uniform distribution of all cations. These results were additionally validated by correlating with energy dispersive spectroscopy mapping of these nanoparticles in a scanning transmission electron microscope. Thus, we have opened the door for probing the nanoscale compositional fluctuations in crucial Li-ion battery cathode materials at an unprecedented spatial resolution of sub-nanometer scale in 3D which can provide critical information for understanding capacity decay mechanisms in these advanced cathode materials.

  1. Visualizing nanoscale 3D compositional fluctuation of lithium in advanced lithium-ion battery cathodes

    DOE PAGES

    Devaraj, Arun; Gu, Meng; Colby, Robert J.; ...

    2015-08-14

    The distribution and concentration of lithium in Li-ion battery cathodes at different stages of cycling is a pivotal factor in determining battery performance. Non-uniform distribution of the transition metal cations has been shown to affect cathode performance; however, the Li is notoriously challenging to characterize with typical high-spatial-resolution imaging techniques. Here, for the first time, laser–assisted atom probe tomography is applied to two advanced Li-ion battery oxide cathode materials—layered Li1.2Ni0.2Mn0.6O2 and spinel LiNi0.5Mn1.5O4—to unambiguously map the three dimensional (3D) distribution of Li at sub-nanometer spatial resolution and correlate it with the distribution of the transition metal cations (M) and themore » oxygen. The as-fabricated layered Li1.2Ni0.2Mn0.6O2 is shown to have Li-rich Li2MO3 phase regions and Li-depleted Li(Ni0.5Mn0.5)O2 regions while in the cycled layered Li1.2Ni0.2Mn0.6O2 an overall loss of Li and presence of Ni rich regions, Mn rich regions and Li rich regions are shown in addition to providing the first direct evidence for Li loss on cycling of layered LNMO cathodes. The spinel LiNi0.5Mn1.5O4 cathode is shown to have a uniform distribution of all cations. These results were additionally validated by correlating with energy dispersive spectroscopy mapping of these nanoparticles in a scanning transmission electron microscope. Thus, we have opened the door for probing the nanoscale compositional fluctuations in crucial Li-ion battery cathode materials at an unprecedented spatial resolution of sub-nanometer scale in 3D which can provide critical information for understanding capacity decay mechanisms in these advanced cathode materials.« less

  2. Combination of thermal extrusion printing and ultrafast laser fabrication for the manufacturing of 3D composite scaffolds

    NASA Astrophysics Data System (ADS)

    Balčiūnas, Evaldas; Lukoševičius, Laurynas; Mackevičiūtė, Dovilė; Rekštytė, Sima; Rutkūnas, Vygandas; Paipulas, Domas; Stankevičiūtė, Karolina; Baltriukienė, Daiva; Bukelskienė, Virginija; Piskarskas, Algis P.; Malinauskas, Mangirdas

    2014-03-01

    We present a novel approach to manufacturing 3D microstructured composite scaffolds for tissue engineering applications. A thermal extrusion 3D printer - a simple, low-cost tabletop device enabling rapid materialization of CAD models in plastics - was used to produce cm-scale microporous scaffolds out of polylactic acid (PLA). The fabricated objects were subsequently immersed in a photosensitive monomer solution and direct laser writing technique (DLW) was used to refine its inner structure by fabricating a fine mesh inside the previously produced scaffold. In addition, a composite material structure out of four different materials fabricated via DLW is presented. This technique, empowered by ultrafast lasers allows 3D structuring with high spatial resolution in a great variety of photosensitive materials. A composite scaffold made of distinct materials and periodicities is acquired after the development process used to wash out non-linked monomers. Another way to modify the 3D printed PLA surfaces was also demonstrated - ablation with femtosecond laser beam. Structure geometry on macro- to micro- scales could be finely tuned by combining these fabrication techniques. Such artificial 3D substrates could be used for cell growth or as biocompatible-biodegradable implants. To our best knowledge, this is the first experimental demonstration showing the creation of composite 3D scaffolds using convenient 3D printing combined with DLW. This combination of distinct material processing techniques enables rapid fabrication of diverse functional micro-featured and integrated devices. Hopefully, the proposed approach will find numerous applications in the field of tissue engineering, as well as in microelectromechanical systems, microfluidics, microoptics and others.

  3. In-Plane Shear Testing of Medium and High Modulus Woven Graphite Fiber Reinforced/Polyimide Composites

    NASA Technical Reports Server (NTRS)

    Gentz, M.; Armentrout, D.; Rupnowski, P.; Kumosa, L.; Shin, E.; Sutter, J. K.; Kumosa, M.

    2004-01-01

    Iosipescu shear tests were performed at room temperature and at 316 C (600 F) o woven composites with either M40J or M60J graphite fibers and PMR-II-50 polyimide resin matrix. The composites were tested as supplied and after thermo-cycling, with the thermo-cycled composites being tested under dry and wet conditions. Acoustic emission (AE) was monitored during the room and high temperature Iosipescu experiments. The shear stresses at the maximum loads and the shear stresses at the significant onset of AE were determined for the composites as function of temperature and conditioning. The combined effects of thermo-cycling and moisture on the strength and stiffness properties of the composites were evaluated. It was determined that the room and high temperature shear stresses at the maximum loads were unaffected by conditioning. However, at room temperature the significant onset of AE was affected by conditioning; the thermal conditioned wet specimens showed the highest shear stress at the onset of AE followed by thermal-conditioned and then as received specimens. Also, at igh temperature the significant onset of AE occurred in some specimens after the maximum load due to the viscoelastoplastic nature of the matrix material.

  4. Notch Sensitivity of Woven Ceramic Matrix Composites Under Tensile Loading: An Experimental, Analytical, and Finite Element Study

    NASA Technical Reports Server (NTRS)

    Haque, A.; Ahmed, L.; Ware, T.; Jeelani, S.; Verrilli, Michael J. (Technical Monitor)

    2001-01-01

    The stress concentrations associated with circular notches and subjected to uniform tensile loading in woven ceramic matrix composites (CMCs) have been investigated for high-efficient turbine engine applications. The CMC's were composed of Nicalon silicon carbide woven fabric in SiNC matrix manufactured through polymer impregnation process (PIP). Several combinations of hole diameter/plate width ratios and ply orientations were considered in this study. In the first part, the stress concentrations were calculated measuring strain distributions surrounding the hole using strain gages at different locations of the specimens during the initial portion of the stress-strain curve before any microdamage developed. The stress concentration was also calculated analytically using Lekhnitskii's solution for orthotropic plates. A finite-width correction factor for anisotropic and orthotropic composite plate was considered. The stress distributions surrounding the circular hole of a CMC's plate were further studied using finite element analysis. Both solid and shell elements were considered. The experimental results were compared with both the analytical and finite element solutions. Extensive optical and scanning electron microscopic examinations were carried out for identifying the fracture behavior and failure mechanisms of both the notched and notched specimens. The stress concentration factors (SCF) determined by analytical method overpredicted the experimental results. But the numerical solution underpredicted the experimental SCF. Stress concentration factors are shown to increase with enlarged hole size and the effects of ply orientations on stress concentration factors are observed to be negligible. In all the cases, the crack initiated at the notch edge and propagated along the width towards the edge of the specimens.

  5. Intermediate Temperature Stress Rupture of Woven SiC Fiber, BN Interphase, SiC Matrix Composites in Air

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Levine, Stanley (Technical Monitor)

    2000-01-01

    Tensile stress-rupture experiments were performed on woven Hi-Nicalon reinforced SiC matrix composites with BN interphases in air. Modal acoustic emission (AE) was used to monitor the damage accumulation in the composites during the tests and microstructural analysis was performed to determine the amount of matrix cracking that occurred for each sample. Fiber fractograph), was also performed for individual fiber failures at the specimen fracture surface to determine the strengths at which fibers failed. The rupture strengths were significantly worse than what would have been expected front the inherent degradation of the fibers themselves when subjected to similar rupture conditions. At higher applied stresses the rate of rupture "?as larger than at lower applied stresses. It was observed that the change in rupture rate corresponded to the onset of through-thickness cracking in the composites themselves. The primary cause of the sen,ere degradation was the ease with which fibers would bond to one another at their closest separation distances, less than 100 nanometers, when exposed to the environment. The near fiber-to-fiber contact in the woven tows enabled premature fiber failure over large areas of matrix cracks due to the stress-concentrations created b), fibers bonded to one another after one or a few fibers fail. i.e. the loss of global load sharing. An@, improvement in fiber-to-fiber separation of this composite system should result in improved stress- rupture properties. A model was den,eloped in order to predict the rupture life-time for these composites based on the probabilistic nature of indin,idual fiber failure at temperature. the matrix cracking state during the rupture test, and the rate of oxidation into a matrix crack. Also incorporated into the model were estimates of the stress-concentration that would occur between the outer rim of fibers in a load-bearing bundle and the unbridged region of a matrix crack after Xia et al. For the lower stresses

  6. Modeling of chemical vapor infiltration for ceramic composites reinforced with layered, woven fabrics

    NASA Technical Reports Server (NTRS)

    Chung, Gui-Yung; Mccoy, Benjamin J.

    1991-01-01

    A homogeneous model is developed for the chemical vapor infiltration by one-dimensional diffusion into a system of layered plies consisting of woven tows containing bundles of filaments. The model predictions of the amount of deposition and the porosity of the sample as a function of time are compared with the predictions of a recent nonhomogeneous model with aligned holes formed by the weave. The nonhomogeneous model allows for diffusion through the aligned holes, into the spaces between plies, and into the gaps around filaments; i.e., three diffusion equations apply. Relative to the nonhomogeneous results, the homogeneous model underestimates the amount of deposition, since the absence of holes and spaces allows earlier occlusion of gaps around filaments and restricts the vapor infiltration.

  7. Comparison of Elevated Temperature Tensile Properties and Fatigue Behavior of Two Variants of a Woven SiC/SiC Composite

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Brewer, David N.; Sreeramesh, Kalluri

    2005-01-01

    Tensile properties (elastic modulus, proportional limit strength, in-plane tensile strength, and strain at failure) of two variants of a woven SiC/SiC composite, manufactured during two separate time periods (9/99 and 1/01), were determined at 1038 and 1204 C by conducting tensile tests on specimens machined from plates. Continuous cycling fatigue tests (R = 0.05) and 20 cpm) were also conducted at the same two temperatures on specimens from both composites. In this study, average tensile properties, 95% confidence intervals associated with the tensile properties, and geometric mean fatigue lives of both composite materials are compared. The observed similarities and differences in the tensile properties are highlighted and an attempt is made to understand the relationship, if any, between the tensile properties and the fatigue behaviors of the two woven composites.

  8. Synthesis of a 3D graphite microball using a microfluidic droplet generator and its polymer composite with core-shell structure.

    PubMed

    Han, Dong Ju; Jung, Jae Hwan; Choi, Jong Seob; Kim, Yong Tae; Seo, Tae Seok

    2013-10-21

    Spherical 3D graphite microballs (3D GMs) and their nanohybrids (3D GM-Fe3O4 nanoparticles) were synthesized by using a microfluidic droplet generator and a thermal evaporation-induced capillary compression method. Using the 3D GM-Fe3O4 nanoparticle as a support for polymerization, 3D GM-polypyrrole composites were produced with a unique core-shell structure.

  9. Low-Velocity Impact Response and Finite Element Analysis of Four-Step 3-D Braided Composites

    NASA Astrophysics Data System (ADS)

    Sun, Baozhong; Zhang, Yan; Gu, Bohong

    2013-08-01

    The low-velocity impact characters of 3-D braided carbon/epoxy composites were investigated from experimental and finite element simulation approaches. The quasi-static tests were carried out at a constant velocity of 2 mm/min on MTS 810.23 material tester system to obtain the indentation load-displacement curves and indentation damages. The low-velocity tests were conducted at the velocities from 1 m/s to 6 m/s (corresponding to the impact energy from 3.22 J to 116 J) on Instron Dynatup 9250 impact tester. The peak force, energy for peak force, time to peak force, and total energy absorption were obtained to determine the impact responses of 3-D braided composites. A unit cell model was established according to the microstructure of 3-D braided composites to derive the constitutive equation. Based on the model, a user-defined material subroutine (VUMAT) has been compiled by FORTRAN and connected with commercial finite element code ABAQUS/Explicit to calculate the impact damage. The unit cell model successfully predicted the impact response of 3-D braided composites. Furthermore, the stress wave propagation and failure mechanisms have been revealed from the finite element simulation results and ultimate damage morphologies of specimens.

  10. Theoretical and experimental study of generation mechanisms for laser ultrasound in woven graphite/epoxy composites with translaminar stitching

    NASA Astrophysics Data System (ADS)

    Friedman, Adam Daniel

    The aerospace industry is beginning to use advanced composite materials for primary load bearing structures and their failure mechanisms must be better understood to predict their behavior in service. The Combined Loads Tests (COLTS) facility is being constructed at the NASA Langley Research Center to characterize these failure mechanisms. Laser based ultrasonic NDE can monitor the samples during dynamic loading without interfering with the structural tests. However, the constraints of implementing laser ultrasound in a structures laboratory reduces the efficiency of the technique. The system has to be ``eye-safe'' because many people will be present during the structural tests. Consequently, laser light has to be delivered through fiber optics and a significant amount of light is lost. Also, the nature of the composite materials makes laser ultrasonic inspection difficult. The composites of interest are formed from woven layers that are stitched through the laminate thickness and bound in a resin matrix. These materials attenuate ultrasound strongly and exhibit a high degree of scattering. Generation mechanisms in laser based ultrasound must be better understood to improve generation efficiency and consequently improve the signal-to-noise ratio. Although some experimental and theoretical studies have been conducted to characterize generation mechanisms, more extensive work is needed for composite materials. Specifically, we are concerned with generation mechanisms in thick, stitched composite structures. We describe a theoretical and experimental investigation of laser generated ultrasound in complex composite materials. We first develop a mathematical model describing the thermoelastic generation of ultrasound in a general anisotropic material. We then present a wide range of experimental data investigating the effects of laser and material parameters on the generated ultrasound. We specifically consider the relationship between laser pulse width, laser

  11. Protein adsorption resistant surface on polymer composite based on 2D- and 3D-controlled grafting of phospholipid moieties

    NASA Astrophysics Data System (ADS)

    Hoshi, Toru; Matsuno, Ryosuke; Sawaguchi, Takashi; Konno, Tomohiro; Takai, Madoka; Ishihara, Kazuhiko

    2008-11-01

    To prepare the biocompatible surface, a phosphorylcholine (PC) group was introduced on this hydroxyl group generated by surface hydrolysis on the polymer composite composed of polyethylene (PE) and poly (vinyl acetate) (PVAc) prepared by supercritical carbon dioxide. Two different procedures such as two-dimensional (2D) modification and three-dimensional (3D) modification were applied to obtain the steady biocompatible surface. 2D modification was that PC groups were directly anchored on the surface of the polymer composite. 3D modification was that phospholipid polymer was grafted from the surface of the polymer composite by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC). The surfaces were characterized by X-ray photoelectron spectroscopy, dynamic water contact angle measurements, and atomic force microscope. The effects of the poly(MPC) chain length on the protein adsorption resistivity were investigated. The protein adsorption on the polymer composite surface with PC groups modified by 2D or 3D modification was significantly reduced as compared with that on the unmodified PE. Further, the amount of protein adsorbed on the 3D modified surface that is poly(MPC)-grafted surface decreased with an increase in the chain length of the poly(MPC). The surface with an arbitrary structure and the characteristic can be constructed by using 2D and 3D modification. We conclude that the polymer composites of PE/PVAc with PC groups on the surface are useful for fabricating biomedical devices due to their good mechanical and surface properties.

  12. Controlled surface topography regulates collective 3D migration by epithelial-mesenchymal composite embryonic tissues.

    PubMed

    Song, Jiho; Shawky, Joseph H; Kim, YongTae; Hazar, Melis; LeDuc, Philip R; Sitti, Metin; Davidson, Lance A

    2015-07-01

    Cells in tissues encounter a range of physical cues as they migrate. Probing single cell and collective migratory responses to physically defined three-dimensional (3D) microenvironments and the factors that modulate those responses are critical to understanding how tissue migration is regulated during development, regeneration, and cancer. One key physical factor that regulates cell migration is topography. Most studies on surface topography and cell mechanics have been carried out with single migratory cells, yet little is known about the spreading and motility response of 3D complex multi-cellular tissues to topographical cues. Here, we examine the response to complex topographical cues of microsurgically isolated tissue explants composed of epithelial and mesenchymal cell layers from naturally 3D organized embryos of the aquatic frog Xenopus laevis. We control topography using fabricated micropost arrays (MPAs) and investigate the collective 3D migration of these multi-cellular systems in these MPAs. We find that the topography regulates both collective and individual cell migration and that dense MPAs reduce but do not eliminate tissue spreading. By modulating cell size through the cell cycle inhibitor Mitomycin C or the spacing of the MPAs we uncover how 3D topographical cues disrupt collective cell migration. We find surface topography can direct both single cell motility and tissue spreading, altering tissue-scale processes that enable efficient conversion of single cell motility into collective movement.

  13. Modeling the Transverse Thermal Conductivity of 2-D SiCf/SiC Composites Made with Woven Fabric

    SciTech Connect

    Youngblood, Gerald E.; Senor, David J.; Jones, Russell H.

    2004-06-30

    The hierarchical two-layer (H2L) model was developed to describe the effective transverse thermal conductivity, Keff, of a 2D-SiCf/SiC composite made from stacked and infiltrated woven fabric layers in terms of constituent properties and microstructural and architectural variables. The H2L model includes the expected effects of fiber-matrix interfacial conductance as well as the effects of high fiber packing fractions within individual tows and the non-uniform nature of 2D-fabric layers that usually include a significant amount of interlayer porosity. Previously, H2L model predictions were compared to measured values of Keff for two versions of DuPont 2D-Hi NicalonÔ/PyC/ICVI-SiC composite, one with a “thin” (0.110 μm) and the other with a “thick” (1.040 μm) pyrocarbon (PyC) fiber coating, and for a 2D-TyrannoÔ SA/”thin” PyC/FCVI-SIC composite made by ORNL. In this study, H2L model predictions are compared to measured Keff-values for a 2D-SiCf/SiC composite made by GE Power Systems (formerly DuPont Lanxide) using the ICVI-process with Hi-NicalonÔ type S fabric. The values of Keff determined for the composite made with the Hi-NicalonÔ type S fabric were significantly greater than Keff-values determined for the composites made with either the Hi-NicalonÔor the TyrannoÔ SA fabrics. Differences in Keff-values were expected for using different fiber types, but major differences also were due to observed microstructural variations between the systems, and as predicted by the H2L model.

  14. Freestanding nanocellulose-composite fibre reinforced 3D polypyrrole electrodes for energy storage applications

    NASA Astrophysics Data System (ADS)

    Wang, Zhaohui; Tammela, Petter; Zhang, Peng; Huo, Jinxing; Ericson, Fredric; Strømme, Maria; Nyholm, Leif

    2014-10-01

    It is demonstrated that 3D nanostructured polypyrrole (3D PPy) nanocomposites can be reinforced with PPy covered nanocellulose (PPy@nanocellulose) fibres to yield freestanding, mechanically strong and porosity optimised electrodes with large surface areas. Such PPy@nanocellulose reinforced 3D PPy materials can be employed as free-standing paper-like electrodes in symmetric energy storage devices exhibiting cell capacitances of 46 F g-1, corresponding to specific electrode capacitances of up to ~185 F g-1 based on the weight of the electrode, and 5.5 F cm-2 at a current density of 2 mA cm-2. After 3000 charge/discharge cycles at 30 mA cm-2, the reinforced 3D PPy electrode material also showed a cell capacitance corresponding to 92% of that initially obtained. The present findings open up new possibilities for the fabrication of high performance, low-cost and environmentally friendly energy-storage devices based on nanostructured paper-like materials.It is demonstrated that 3D nanostructured polypyrrole (3D PPy) nanocomposites can be reinforced with PPy covered nanocellulose (PPy@nanocellulose) fibres to yield freestanding, mechanically strong and porosity optimised electrodes with large surface areas. Such PPy@nanocellulose reinforced 3D PPy materials can be employed as free-standing paper-like electrodes in symmetric energy storage devices exhibiting cell capacitances of 46 F g-1, corresponding to specific electrode capacitances of up to ~185 F g-1 based on the weight of the electrode, and 5.5 F cm-2 at a current density of 2 mA cm-2. After 3000 charge/discharge cycles at 30 mA cm-2, the reinforced 3D PPy electrode material also showed a cell capacitance corresponding to 92% of that initially obtained. The present findings open up new possibilities for the fabrication of high performance, low-cost and environmentally friendly energy-storage devices based on nanostructured paper-like materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c

  15. Composite lithium metal anode by melt infusion of lithium into a 3D conducting scaffold with lithiophilic coating

    PubMed Central

    Liang, Zheng; Lin, Dingchang; Zhao, Jie; Lu, Zhenda; Liu, Yayuan; Liu, Chong; Lu, Yingying; Wang, Haotian; Yan, Kai; Tao, Xinyong; Cui, Yi

    2016-01-01

    Lithium metal-based battery is considered one of the best energy storage systems due to its high theoretical capacity and lowest anode potential of all. However, dendritic growth and virtually relative infinity volume change during long-term cycling often lead to severe safety hazards and catastrophic failure. Here, a stable lithium–scaffold composite electrode is developed by lithium melt infusion into a 3D porous carbon matrix with “lithiophilic” coating. Lithium is uniformly entrapped on the matrix surface and in the 3D structure. The resulting composite electrode possesses a high conductive surface area and excellent structural stability upon galvanostatic cycling. We showed stable cycling of this composite electrode with small Li plating/stripping overpotential (<90 mV) at a high current density of 3 mA/cm2 over 80 cycles. PMID:26929378

  16. Freestanding nanocellulose-composite fibre reinforced 3D polypyrrole electrodes for energy storage applications.

    PubMed

    Wang, Zhaohui; Tammela, Petter; Zhang, Peng; Huo, Jinxing; Ericson, Fredric; Strømme, Maria; Nyholm, Leif

    2014-11-07

    It is demonstrated that 3D nanostructured polypyrrole (3D PPy) nanocomposites can be reinforced with PPy covered nanocellulose (PPy@nanocellulose) fibres to yield freestanding, mechanically strong and porosity optimised electrodes with large surface areas. Such PPy@nanocellulose reinforced 3D PPy materials can be employed as free-standing paper-like electrodes in symmetric energy storage devices exhibiting cell capacitances of 46 F g(-1), corresponding to specific electrode capacitances of up to ∼185 F g(-1) based on the weight of the electrode, and 5.5 F cm(-2) at a current density of 2 mA cm(-2). After 3000 charge/discharge cycles at 30 mA cm(-2), the reinforced 3D PPy electrode material also showed a cell capacitance corresponding to 92% of that initially obtained. The present findings open up new possibilities for the fabrication of high performance, low-cost and environmentally friendly energy-storage devices based on nanostructured paper-like materials.

  17. Using a magnetite/thermoplastic composite in 3D printing of direct replacements for commercially available flow sensors

    NASA Astrophysics Data System (ADS)

    Leigh, S. J.; Purssell, C. P.; Billson, D. R.; Hutchins, D. A.

    2014-09-01

    Flow sensing is an essential technique required for a wide range of application environments ranging from liquid dispensing to utility monitoring. A number of different methodologies and deployment strategies have been devised to cover the diverse range of potential application areas. The ability to easily create new bespoke sensors for new applications is therefore of natural interest. Fused deposition modelling is a 3D printing technology based upon the fabrication of 3D structures in a layer-by-layer fashion using extruded strands of molten thermoplastic. The technology was developed in the late 1980s but has only recently come to more wide-scale attention outside of specialist applications and rapid prototyping due to the advent of low-cost 3D printing platforms such as the RepRap. Due to the relatively low-cost of the printers and feedstock materials, these printers are ideal candidates for wide-scale installation as localized manufacturing platforms to quickly produce replacement parts when components fail. One of the current limitations with the technology is the availability of functional printing materials to facilitate production of complex functional 3D objects and devices beyond mere concept prototypes. This paper presents the formulation of a simple magnetite nanoparticle-loaded thermoplastic composite and its incorporation into a 3D printed flow-sensor in order to mimic the function of a commercially available flow-sensing device. Using the multi-material printing capability of the 3D printer allows a much smaller amount of functional material to be used in comparison to the commercial flow sensor by only placing the material where it is specifically required. Analysis of the printed sensor also revealed a much more linear response to increasing flow rate of water showing that 3D printed devices have the potential to at least perform as well as a conventionally produced sensor.

  18. The Effect of Temperature and Nanoclay on the Low Velocity and Ballistic Behavior of Woven Glass-Fiber Reinforced Composites

    NASA Astrophysics Data System (ADS)

    Patrin, Lauren

    The objective of this research was to study the effect of nanoclay and temperature on the behavior of woven glass-fabric reinforced epoxy composite under low velocity and ballistic impacts. The materials used in manufacturing the composite were S2 (6181) glass-fibers, epoxy resin (EPON 828), hardener (Epikure 3230), nanoclay and Heloxy 61 modifier. The nanoclay addition was 0%, 1%, 3% and 5% by weight, with respect to the resin. All specimens were manufactured at the City College facilities using vacuum infusion. Tensile tests were conducted to characterize the material and obtain the Young's modulus, ultimate stress, failure strain, Poisson's ratio, shear modulus and shear strength and their variation with nanoclay percentage and temperature. The tests were conducted at room temperature (21°C/70°F), -54°C (-65°F), -20°C (-4°F), 49°C (120°F) and 71°C (160°F). Next composite specimens with 0%, 1%, 3% and 5% nanoclay by weight, with respect to the resin, were subjected to low velocity impact at the previously specified temperatures to determine dynamic force, displacement and energy correlations. The extent of damage was studied using the ultrasound technique. Then ballistic tests were conducted on the nanoclay infused specimens at room temperature to obtain the ballistic limit (V50) and the damage behavior of the composite. The dynamic finite element analysis (FEA) software LS-DYNA was used to model and simulate the results of low velocity impact tests. Good agreement was obtained between experimental and numerical (FEA) results. Analytical analyses were undertaken to compare the results from the tensile experiments. The finite element analysis (FEA) allowed for further analytical comparison of the results. The FEA platform used was LS-DYNA due to its proficient dynamic and damage capabilities in composite materials. The FEA was used to model and simulate the low velocity impacts and compare the results to experiments.

  19. Modeling of Damage Initiation and Progression in a SiC/SiC Woven Ceramic Matrix Composite

    NASA Technical Reports Server (NTRS)

    Mital, Subodh K.; Goldberg, Robert K.; Bonacuse, Peter J.

    2012-01-01

    The goal of an ongoing project at NASA Glenn is to investigate the effects of the complex microstructure of a woven ceramic matrix composite and its variability on the effective properties and the durability of the material. Detailed analysis of these complex microstructures may provide clues for the material scientists who `design the material? or to structural analysts and designers who `design with the material? regarding damage initiation and damage propagation. A model material system, specifically a five-harness satin weave architecture CVI SiC/SiC composite composed of Sylramic-iBN fibers and a SiC matrix, has been analyzed. Specimens of the material were serially sectioned and polished to capture the detailed images of fiber tows, matrix and porosity. Open source analysis tools were used to isolate various constituents and finite elements models were then generated from simplified models of those images. Detailed finite element analyses were performed that examine how the variability in the local microstructure affected the macroscopic behavior as well as the local damage initiation and progression. Results indicate that the locations where damage initiated and propagated is linked to specific microstructural features.

  20. The notched strength and unstable fracture criterion in plain woven glass/epoxy composites with a crack for transport

    SciTech Connect

    Ishihara, T.; Kim, J.K.; Kim, D.S.

    1995-10-01

    The fracture behavior of plain woven glass/epoxy composite plates with a notch is investigated under static tensile loading. It is shown in this paper that the characteristic length associated with the point stress criterion depends on the crack length. To predict the notched tensile strength, the point stress criterion proposed by Whitney and Nuismer (1974) are modified. The condition of unstable crack growth in the presence of a pre-existing flaw (machined notch) is examined by means of the maximum stress intensity factor K{sub max} using maximum load P{sub max}. The values of K{sub max} evaluated from energy release rate G{sub max} (the compliance method) and the standard expression normally used for isotropic materials (the isotropic method) indicate a wide difference. Therefore, in regard to anisotropy and heterogeneity of the composite materials studied, the modified shape correction factor f* (a/w) is obtained, K{sub max} evaluated by the compliance method a little or insignificantly depends on the initial crack length a, the specimen thickness B, the crack angle 0 and the specimen geometry.

  1. Cell-laden 3D bioprinting hydrogel matrix depending on different compositions for soft tissue engineering: Characterization and evaluation.

    PubMed

    Park, Jisun; Lee, Sang Jin; Chung, Solchan; Lee, Jun Hee; Kim, Wan Doo; Lee, Jae Young; Park, Su A

    2017-02-01

    Cell-printing techniques that can construct three-dimensional (3D) structures with biocompatible materials and cells are of great interest for various biomedical applications, such as tissue engineering and drug-screening studies. For successful cell-printing with cells, bioinks are critical for both the processability of printing and the viability of printed cells. However, the influence of composition on 3D bio-printing with cells has not been well explored. In this study, we investigated different compositions of alginate bioinks by varying the concentrations of high molecular weight alginate (High Alg) and low molecular weight alginate (Low Alg). Bioinks of 3wt% alginate containing High Alg alone or a 1:2 (Low Alg:High Alg) composite allowed for the construction of 3D scaffolds with good processability and shapes. Cell-printing with fibroblasts and in vitro culture studies revealed good viability and growth of the printed cells after up to 7days of culture. Bioinks prepared with High and Low Alg at a 2:1 ratio exhibited better cell growth compared with those of other compositions. This study progresses the design and applications of alginate-based bioinks for cell-printing platforms in soft tissue engineering.

  2. Contrast Enhancement of MicroCT Scans to Aid 3D Modelling of Carbon Fibre Fabric Composites

    NASA Astrophysics Data System (ADS)

    Djukic, Luke P.; Pearce, Garth M.; Herszberg, Israel; Bannister, Michael K.; Mollenhauer, David H.

    2013-12-01

    This paper presents a methodology for volume capture and rendering of plain weave and multi-layer fabric meso-architectures within a consolidated, cured laminate. Micro X-ray Computed Tomography (MicroCT) is an excellent tool for the non-destructive visualisation of material microstructures however the contrast between tows and resin is poor for carbon fibre composites. Firstly, this paper demonstrates techniques to improve the contrast of the microCT images by introducing higher density materials such as gold, iodine and glass into the fabric. Two approaches were demonstrated to be effective for enhancing the differentiation between the tows in the reconstructed microCT visualisations. Secondly, a method of generating three-dimensional volume models of woven composites using microCT scan data is discussed. The process of generating a model is explained from initial manufacture with the aid of an example plain weave fabric. These methods are to be used in the finite element modelling of three-dimensional fabric preforms in future work.

  3. 3D printing PLGA: a quantitative examination of the effects of polymer composition and printing parameters on print resolution.

    PubMed

    Guo, Ting; Holzberg, Timothy R; Lim, Casey G; Gao, Feng; Gargava, Ankit; Trachtenberg, Jordan E; Mikos, Antonios G; Fisher, John P

    2017-04-12

    In the past few decades, 3D printing has played a significant role in fabricating scaffolds with consistent, complex structure that meet patient-specific needs in future clinical applications. Although many studies have contributed to this emerging field of additive manufacturing, which includes material development and computer-aided scaffold design, current quantitative analyses do not correlate material properties, printing parameters, and printing outcomes to a great extent. A model that correlates these properties has tremendous potential to standardize 3D printing for tissue engineering and biomaterial science. In this study, we printed poly(lactic-co-glycolic acid) (PLGA) utilizing a direct melt extrusion technique without additional ingredients. We investigated PLGA with various lactic acid:glycolic acid (LA:GA) molecular weight ratios and end caps to demonstrate the dependence of the extrusion process on the polymer composition. Micro-computed tomography was then used to evaluate printed scaffolds containing different LA:GA ratios, composed of different fiber patterns, and processed under different printing conditions. We built a statistical model to reveal the correlation and predominant factors that determine printing precision. Our model showed a strong linear relationship between the actual and predicted precision under different combinations of printing conditions and material compositions. This quantitative examination establishes a significant foreground to 3D print biomaterials following a systematic fabrication procedure. Additionally, our proposed statistical models can be applied to couple specific biomaterials and 3D printing applications for patient implants with particular requirements.

  4. An Update on Design Tools for Optimization of CMC 3D Fiber Architectures

    NASA Technical Reports Server (NTRS)

    Lang, J.; DiCarlo, J.

    2012-01-01

    Objective: Describe and up-date progress for NASA's efforts to develop 3D architectural design tools for CMC in general and for SIC/SiC composites in particular. Describe past and current sequential work efforts aimed at: Understanding key fiber and tow physical characteristics in conventional 2D and 3D woven architectures as revealed by microstructures in the literature. Developing an Excel program for down-selecting and predicting key geometric properties and resulting key fiber-controlled properties for various conventional 3D architectures. Developing a software tool for accurately visualizing all the key geometric details of conventional 3D architectures. Validating tools by visualizing and predicting the Internal geometry and key mechanical properties of a NASA SIC/SIC panel with a 3D orthogonal architecture. Applying the predictive and visualization tools toward advanced 3D orthogonal SiC/SIC composites, and combining them into a user-friendly software program.

  5. Understanding Plasticity and Fracture in Aluminum Alloys and their Composites by 3D X-ray Synchrotron Tomography and Microdiffraction

    NASA Astrophysics Data System (ADS)

    Hruby, Peter

    Aluminum alloys and their composites are attractive materials for applications requiring high strength-to-weight ratios and reasonable cost. Many of these applications, such as those in the aerospace industry, undergo fatigue loading. An understanding of the microstructural damage that occurs in these materials is critical in assessing their fatigue resistance. Two distinct experimental studies were performed to further the understanding of fatigue damage mechanisms in aluminum alloys and their composites, specifically fracture and plasticity. Fatigue resistance of metal matrix composites (MMCs) depends on many aspects of composite microstructure. Fatigue crack growth behavior is particularly dependent on the reinforcement characteristics and matrix microstructure. The goal of this work was to obtain a fundamental understanding of fatigue crack growth behavior in SiC particle-reinforced 2080 Al alloy composites. In situ X-ray synchrotron tomography was performed on two samples at low (R=0.1) and at high (R=0.6) R-ratios. The resulting reconstructed images were used to obtain three-dimensional (3D) rendering of the particles and fatigue crack. Behaviors of the particles and crack, as well as their interaction, were analyzed and quantified. Four-dimensional (4D) visual representations were constructed to aid in the overall understanding of damage evolution. During fatigue crack growth in ductile materials, a plastic zone is created in the region surrounding the crack tip. Knowledge of the plastic zone is important for the understanding of fatigue crack formation as well as subsequent growth behavior. The goal of this work was to quantify the 3D size and shape of the plastic zone in 7075 Al alloys. X-ray synchrotron tomography and Laue microdiffraction were used to non-destructively characterize the volume surrounding a fatigue crack tip. The precise 3D crack profile was segmented from the reconstructed tomography data. Depth-resolved Laue patterns were obtained using

  6. Intermediate Temperature Stress Rupture of a Woven Hi-Nicalon, BN-Interphase, SiC Matric Composite in Air

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Hurst, Janet; Brewer, David

    1999-01-01

    Woven Hi-Nicalon (TM) reinforced melt-infiltrated SiC matrix composites were tested under tensile stress-rupture conditions in air at intermediate temperatures. A comprehensive examination of the damage state and the fiber properties at failure was performed. Modal acoustic emission analysis was used to monitor damage during the experiment. Extensive microscopy of the composite fracture surfaces and the individual fiber fracture surfaces was used to determine the mechanisms leading to ultimate failure. The rupture properties of these composites were significantly worse than expected compared to the fiber properties under similar conditions. This was due to the oxidation of the BN interphase. Oxidation occurred through the matrix cracks that intersected the surface or edge of a tensile bar. These oxidation reactions resulted in minor degradation to fiber strength and strong bonding of the fibers to one another at regions of near fiber-to-fiber contact. It was found that two regimes for rupture exist for this material: a high stress regime where rupture occurs at a fast rate and a low stress regime where rupture occurs at a slower rate. For the high stress regime, the matrix damage state consisted of through thickness cracks. The average fracture strength of fibers that were pulled-out (the final fibers to break before ultimate failure) was controlled by the slow-crack growth rupture criterion in the literature for individual Hi-Nicalon (TM) fibers. For the low stress regime, the matrix damage state consisted of microcracks which grew during the rupture test. The average fracture strength of fibers that were pulled-out in this regime was the same as the average fracture strength of individual fibers pulled out in as-produced composites tested at room temperature.

  7. Optimizing Photo-Encapsulation Viability of Heart Valve Cell Types in 3D Printable Composite Hydrogels.

    PubMed

    Kang, Laura Hockaday; Armstrong, Patrick A; Lee, Lauren Julia; Duan, Bin; Kang, Kevin Heeyong; Butcher, Jonathan Talbot

    2017-02-01

    Photocrosslinking hydrogel technologies are attractive for the biofabrication of cardiovascular soft tissues, but 3D printing success is dependent on multiple variables. In this study we systematically test variables associated with photocrosslinking hydrogels (photoinitiator type, photoinitiator concentration, and light intensity) for their effects on encapsulated cells in an extrusion 3D printable mixture of methacrylated gelatin/poly-ethylene glycol diacrylate/alginate (MEGEL/PEGDA3350/alginate). The fabrication conditions that produced desired hydrogel mechanical properties were compared against those that optimize aortic valve or mesenchymal stem cell viability. In the 3D hydrogel culture environment and fabrication setting studied, Irgacure can increase hydrogel stiffness with a lower proportional decrease in encapsulated cell viability compared to VA086. Human adipose derived mesenchymal stem cells (HADMSC) survived increasing photoinitiator concentrations in photo-encapsulation conditions better than aortic valve interstitial cells (HAVIC) and aortic valve sinus smooth muscle cells (HASSMC). Within the range of photo-encapsulation fabrication conditions tested with MEGEL/PEGDA/alginate (0.25-1.0% w/v VA086, 0.025-0.1% w/v Irgacure 2959, and 365 nm light intensity 2-136 mW/cm(2)), the highest viabilities achieved were 95, 93, and 93% live for HASSMC, HAVIC, and HADMSC respectively. These results identify parameter combinations that optimize cell viability during 3D printing for multiple cell types. These results also indicate that general oxidative stress is higher in photocrosslinking conditions that induce lower cell viability. However, suppressing this increase in intracellular oxidative stress did not improve cell viability, which suggests that other stress mechanisms also contribute.

  8. Self-Assembly of 3-D Multifunctional Ceramic Composites for Photonics and Sensors

    DTIC Science & Technology

    2011-05-02

    discoveries supported by our earlier MURI work. Specific applications include new IR photonic crystal based filters for multispectral imaging, optical ...Johnson, A. J. Baca, J. A. Rogers, J. A. Lewis and P. V. Braun: Multidimensional Architectures for Functional Optical Devices, Advanced Materials, 22...P.V. Braun, “Templated Growth of and Optical Emission from Single Crystal GaAs 3D Photonic Crystals,” SPIE Photonics West, January 2010

  9. Graphene-based 3D composite hydrogel by anchoring Co3O4 nanoparticles with enhanced electrochemical properties.

    PubMed

    Yuan, Jingjing; Zhu, Junwu; Bi, Huiping; Meng, Xiaoqian; Liang, Shiming; Zhang, Lili; Wang, Xin

    2013-08-21

    Three-dimensional (3D) graphene-based composite materials have attracted increasing attention, owing to their specific surface area, high conductivity and electronic interactions. Here, we report a convenient route to fabricate a 3D Co3O4/Graphene Hydrogel (CGH) composite as an electrode material for supercapacitors. Utilizing the gelation of a graphene oxide dispersion enables the anchoring of Co3O4 nanoparticles on the graphene sheet surfaces and formation of the hydrogel simultaneously. Remarkably, the spherical Co3O4 particles can serve as spacers to keep the neighboring graphene sheets separated. The CGH exhibits a high specific capacitance (Cs) of 757.5 F g(-1) at a current density of 0.5 A g(-1), indicating its potential application as an electrode material for supercapacitors.

  10. A study on the influence of process parameters on the Mechanical Properties of 3D printed ABS composite

    NASA Astrophysics Data System (ADS)

    Jaya Christiyan, K. G.; Chandrasekhar, U.; Venkateswarlu, K.

    2016-02-01

    Additive Manufacturing (AM) technologies have been emerged as a fabrication method to obtain engineering components within a short span of time. Desktop 3D printing, also referred as additive layer manufacturing technology is one of the powerful method of rapid prototyping (RP) technique that fabricates three dimensional engineering components. In this method, 3D digital CAD data is converted directly to a product. In the present investigation, ABS + hydrous magnesium silicate composite was considered as the starting material. Mechanical properties of ABS + hydrous magnesium silicate composite material were evaluated. ASTM D638 and ASTM D760 standards were followed for carrying out tensile and flexural tests, respectively. Samples with different layer thickness and printing speed were prepared. Based on the experimental results, it is suggested that low printing speed, and low layer thickness has resulted maximum tensile and flexural strength, as compared to all the other process parameters samples.

  11. Ice-Templated Assembly Strategy to Construct 3D Boron Nitride Nanosheet Networks in Polymer Composites for Thermal Conductivity Improvement.

    PubMed

    Zeng, Xiaoliang; Yao, Yimin; Gong, Zhengyu; Wang, Fangfang; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2015-12-01

    Owing to the growing heat removal issue of modern electronic devices, polymer composites with high thermal conductivity have drawn much attention in the past few years. However, a traditional method to enhance the thermal conductivity of the polymers by addition of inorganic fillers usually creates composite with not only limited thermal conductivity but also other detrimental effects due to large amount of fillers required. Here, novel polymer composites are reported by first constructing 3D boron nitride nanosheets (3D-BNNS) network using ice-templated approach and then infiltrating them with epoxy matrix. The obtained polymer composites exhibit a high thermal conductivity (2.85 W m(-1) K(-1)), a low thermal expansion coefficient (24-32 ppm K(-1)), and an increased glass transition temperature (T(g)) at relatively low BNNSs loading (9.29 vol%). These results demonstrate that this approach opens a new avenue for design and preparation of polymer composites with high thermal conductivity. The polymer composites are potentially useful in advanced electronic packaging techniques, namely, thermal interface materials, underfill materials, molding compounds, and organic substrates.

  12. Characterizing microscale aluminum composite layer properties on silicon solar cells with hybrid 3D scanning force measurements.

    PubMed

    Bae, Sung-Kuk; Choi, Beomjoon; Chung, Haseung; Shin, Seungwon; Song, Hee-eun; Seo, Jung Hwan

    2016-03-07

    This article presents a novel technique to estimate the mechanical properties of the aluminum composite layer on silicon solar cells by using a hybrid 3-dimensional laser scanning force measurement (3-D LSFM) system. The 3-D LSFM system measures the material properties of sub-layers constituting a solar cell. This measurement is critical for realizing high-efficient ultra-thin solar cells. The screen-printed aluminum layer, which significantly affects the bowing phenomenon, is separated from the complete solar cell by removing the silicon (Si) layer with deep reactive ion etching. An elastic modulus of ~15.1 GPa and a yield strength of ~35.0 MPa for the aluminum (Al) composite layer were obtained by the 3-D LSFM system. In experiments performed for 6-inch Si solar cells, the bowing distances decreased from 12.02 to 1.18 mm while the Si layer thicknesses increased from 90 to 190 μm. These results are in excellent agreement with the theoretical predictions for ultra-thin Si thickness (90 μm) based on the obtained Al composite layer properties.

  13. Characterizing microscale aluminum composite layer properties on silicon solar cells with hybrid 3D scanning force measurements

    NASA Astrophysics Data System (ADS)

    Bae, Sung-Kuk; Choi, Beomjoon; Chung, Haseung; Shin, Seungwon; Song, Hee-Eun; Seo, Jung Hwan

    2016-03-01

    This article presents a novel technique to estimate the mechanical properties of the aluminum composite layer on silicon solar cells by using a hybrid 3-dimensional laser scanning force measurement (3-D LSFM) system. The 3-D LSFM system measures the material properties of sub-layers constituting a solar cell. This measurement is critical for realizing high-efficient ultra-thin solar cells. The screen-printed aluminum layer, which significantly affects the bowing phenomenon, is separated from the complete solar cell by removing the silicon (Si) layer with deep reactive ion etching. An elastic modulus of ~15.1 GPa and a yield strength of ~35.0 MPa for the aluminum (Al) composite layer were obtained by the 3-D LSFM system. In experiments performed for 6-inch Si solar cells, the bowing distances decreased from 12.02 to 1.18 mm while the Si layer thicknesses increased from 90 to 190 μm. These results are in excellent agreement with the theoretical predictions for ultra-thin Si thickness (90 μm) based on the obtained Al composite layer properties.

  14. Characterizing microscale aluminum composite layer properties on silicon solar cells with hybrid 3D scanning force measurements

    PubMed Central

    Bae, Sung-Kuk; Choi, Beomjoon; Chung, Haseung; Shin, Seungwon; Song, Hee-eun; Seo, Jung Hwan

    2016-01-01

    This article presents a novel technique to estimate the mechanical properties of the aluminum composite layer on silicon solar cells by using a hybrid 3-dimensional laser scanning force measurement (3-D LSFM) system. The 3-D LSFM system measures the material properties of sub-layers constituting a solar cell. This measurement is critical for realizing high-efficient ultra-thin solar cells. The screen-printed aluminum layer, which significantly affects the bowing phenomenon, is separated from the complete solar cell by removing the silicon (Si) layer with deep reactive ion etching. An elastic modulus of ~15.1 GPa and a yield strength of ~35.0 MPa for the aluminum (Al) composite layer were obtained by the 3-D LSFM system. In experiments performed for 6-inch Si solar cells, the bowing distances decreased from 12.02 to 1.18 mm while the Si layer thicknesses increased from 90 to 190 μm. These results are in excellent agreement with the theoretical predictions for ultra-thin Si thickness (90 μm) based on the obtained Al composite layer properties. PMID:26948248

  15. Estimating the composition of hydrates from a 3D seismic dataset near Penghu Canyon on Chinese passive margin offshore Taiwan

    NASA Astrophysics Data System (ADS)

    Chi, Wu-Cheng

    2016-04-01

    A bottom-simulating reflector (BSR), representing the base of the gas hydrate stability zone, can be used to estimate geothermal gradients under seafloor. However, to derive temperature estimates at the BSR, the correct hydrate composition is needed to calculate the phase boundary. Here we applied the method by Minshull and Keddie to constrain the hydrate composition and the pore fluid salinity. We used a 3D seismic dataset offshore SW Taiwan to test the method. Different from previous studies, we have considered the effects of 3D topographic effects using finite element modelling and also depth-dependent thermal conductivity. Using a pore water salinity of 2% at the BSR depth as found from the nearby core samples, we successfully used 99% methane and 1% ethane gas hydrate phase boundary to derive a sub-bottom depth vs. temperature plot which is consistent with the seafloor temperature from in-situ measurements. The results are also consistent with geochemical analyses of the pore fluids. The derived regional geothermal gradient is 40.1oC/km, which is similar to 40oC/km used in the 3D finite element modelling used in this study. This study is among the first documented successful use of Minshull and Keddie's method to constrain seafloor gas hydrate composition.

  16. Multifunctional graphene woven fabrics

    PubMed Central

    Li, Xiao; Sun, Pengzhan; Fan, Lili; Zhu, Miao; Wang, Kunlin; Zhong, Minlin; Wei, Jinquan; Wu, Dehai; Cheng, Yao; Zhu, Hongwei

    2012-01-01

    Tailoring and assembling graphene into functional macrostructures with well-defined configuration are key for many promising applications. We report on a graphene-based woven fabric (GWF) prepared by interlacing two sets of graphene micron-ribbons where the ribbons pass each other essentially at right angles. By using a woven copper mesh as the template, the GWF grown from chemical vapour deposition retains the network configuration of the copper mesh. Embedded into polymer matrices, it has significant flexibility and strength gains compared with CVD grown graphene films. The GWFs display both good dimensional stability in both the warp and the weft directions and the combination of film transparency and conductivity could be optimized by tuning the ribbon packing density. The GWF creates a platform to integrate a large variety of applications, e.g., composites, strain sensors and solar cells, by taking advantages of the special structure and properties of graphene. PMID:22563524

  17. Effect of Sericin on Mechanical Behavior of Composite Material Reinforced by Silk Woven Fabric

    NASA Astrophysics Data System (ADS)

    Kimura, Teruo; Ino, Haruhiro; Hanada, Koji; Katori, Sigetaka

    Recent, attention has been given to shift from glass fibers and carbon fibers to natural fibers for FRP composites for the goal of protecting the environment. This paper concerned with the application of silk fabric for composite materials. Polypropylene (PP) was used for the matrix material and the silk fabric composites were molded using a compression molding method. Especially, the effect of sericin on mechanical behaviors of composite materials was discussed. Good adhesion between silk and PP was obtained by removing the sericin existing around the fibroin. The tensile modulus of composite decreased with decreasing the sericin because of the flexibility of silk fibers without sericin. In particular, the higher Izod impact value was obtained for the composites containing the silk fibers without sericin.

  18. Experimental Investigation of the Interface Behavior of Balanced and Unbalanced E-Glass/Polyester Woven Fabric Composite Laminates

    NASA Astrophysics Data System (ADS)

    Triki, E.; Zouari, B.; Jarraya, A.; Dammak, F.

    2013-12-01

    The aim of this work is to study the influence of weave structure on the crack growth behavior of thick E-glass/polyester woven fabric composites laminates. Two different types of laminates were fabricated: (i) balanced: plain weave (taffetas T)/chopped strand mat weave (M) [T/M]6 and (ii) unbalanced: 4-hardness satin weave (S)/chopped strand mat weave [S/M]7. In order to accurately predict damage criticality in such structures, mixed mode fracture toughness data is required. So, the experiments were conducted using standards delamination tests under mixed mode loading and pure mode loading. These tests were carried out in mode II using End Load Split (ELS) tests and in mixed-mode I+II by Mixed Mode Flexure (MMF) tests under static conditions. The test methodology used for the experiments will be presented. The experimental results have been expressed in terms of total strain energy release rate and R-curves. The fracture toughness results show that the T/M interface is more resistant to delamination than the S/M interface.

  19. Numerical simulating and experimental study on the woven carbon fiber-reinforced composite laminates under low-velocity impact

    NASA Astrophysics Data System (ADS)

    Liu, Hanyang; Tang, Zhanwen; Pan, Lingying; Zhao, Weidong; Sun, Baogang; Jiang, Wenge

    2016-05-01

    Impact damage has been identified as a critical form of the defects that constantly threatened the reliability of composite structures, such as those used in the aerospace structures and systems. Low energy impacts can introduce barely visible damage and cause the degradation of structural stiffness, furthermore, the flaws caused by low-velocity impact are so dangerous that they can give rise to the further extended delaminations. In order to improve the reliability and load carrying capacity of composite laminates under low-velocity impact, in this paper, the numerical simulatings and experimental studies on the woven fiber-reinforced composite laminates under low-velocity impact with impact energy 16.7J were discussed. The low velocity impact experiment was carried out through drop-weight system as the reason of inertia effect. A numerical progressive damage model was provided, in which the damages of fiber, matrix and interlamina were considered by VUMT subroutine in ABAQUS, to determine the damage modes. The Hashin failure criteria were improved to cover the failure modes of fiber failure in the directions of warp/weft and delaminations. The results of Finite Element Analysis (FEA) were compared with the experimental results of nondestructive examination including the results of ultrasonic C-scan, cross-section stereomicroscope and contact force - time history curves. It is found that the response of laminates under low-velocity impact could be divided into stages with different damage. Before the max-deformation of the laminates occurring, the matrix cracking, fiber breakage and delaminations were simulated during the impactor dropping. During the releasing and rebounding period, matrix cracking and delaminations areas kept increasing in the laminates because of the stress releasing of laminates. Finally, the simulating results showed the good agreements with the results of experiment.

  20. Measuring and modeling the thermal conductivities of three-dimensionally woven fabric composites

    NASA Astrophysics Data System (ADS)

    Schuster, J.; Heider, D.; Sharp, K.; Glowania, M.

    2009-03-01

    The effect of a three-dimensional fiber reinforcement on the out-of-plane thermal conductivity of composite materials is investigated. Composite preforms with different fibers in the thickness direction were fabricated. After in fusion by using a vacuum-assisted resin transfer molding process, their through-thickness thermal conductivities were evaluated. The measured thermal conductivities showed a significant increase compared with those of a typical laminated composite. Although the through-thickness thermal conductivity of the samples increased with through-thickness fiber volume fraction, its values did not match those predicted by the simple rule of mixtures. By using finite-element models to better under stand the behavior of the composite material, improvements in an existing analytical model were performed to predict the effective thermal conductivity as a function of material properties and in-contact thermal properties of the composite.

  1. Advanced Li-Ion Hybrid Supercapacitors Based on 3D Graphene-Foam Composites.

    PubMed

    Liu, Wenwen; Li, Jingde; Feng, Kun; Sy, Abel; Liu, Yangshuai; Lim, Lucas; Lui, Gregory; Tjandra, Ricky; Rasenthiram, Lathankan; Chiu, Gordon; Yu, Aiping

    2016-10-05

    Li-ion hybrid supercapacitors (LIHSs) have recently attracted increasing attention as a new and promising energy storage device. However, it is still a great challenge to construct novel LIHSs with high-performance due to the majority of battery-type anodes retaining the sluggish kinetics of Li-ion storage and most capacitor-type cathodes with low specific capacitance. To solve this problem, 3D graphene-wrapped MoO3 nanobelt foam with the unique porous network structure has been designed and prepared as anode material, which delivers high capacity, improved rate performance, and enhanced cycle stability. First-principles calculation reveals that the combination of graphene dramatically reduces the diffusion energy barrier of Li(+) adsorbed on the surface of MoO3 nanobelt, thus improving its electrochemical performance. Furthermore, 3D graphene-wrapped polyaniline nanotube foam derived carbon is employed as a new type of capacitor-type cathode, demonstrating high specific capacitance, good rate performance, and long cycle stability. Benefiting from these two graphene foam-enhanced materials, the constructed LIHSs show a wide operating voltage range (3.8 V), a long stable cycle life (90% capacity retention after 3000 cycles), a high energy density (128.3 Wh·kg(-1)), and a high power density (13.5 kW·kg(-1)). These encouraging performances indicate that the obtained LIHSs may have promising prospect as next-generation energy-storage devices.

  2. Superior Mechanical Properties of Epoxy Composites Reinforced by 3D Interconnected Graphene Skeleton.

    PubMed

    Ni, Ya; Chen, Lei; Teng, Kunyue; Shi, Jie; Qian, Xiaoming; Xu, Zhiwei; Tian, Xu; Hu, Chuansheng; Ma, Meijun

    2015-06-03

    Epoxy-based composites reinforced by three-dimensional graphene skeleton (3DGS) were fabricated in resin transfer molding method with respect to the difficulty in good dispersion and arrangement of graphene sheets in composites by directly mixing graphene and epoxy. 3DGS was synthesized in the process of self-assembly and reduction with poly(amidoamine) dendrimers. In the formation of 3DGS, graphene sheets were in good dispersion and ordered state, which resulted in exceptional mechanical properties and thermal stability for epoxy composites. For 3DGS/epoxy composites, the tensile and compressive strengths significantly increased by 120.9% and 148.3%, respectively, as well as the glass transition temperature, which increased by a notable 19 °C, unlike the thermal exfoliation graphene/epoxy composites via direct-mixing route, which increased by only 0.20 wt % content of fillers. Relative to the graphene/epoxy composites in direct-mixing method mentioned in literature, the increase in tensile and compressive strengths of 3DGS/epoxy composites was at least twofold and sevenfold, respectively. It can be expected that 3DGS, which comes from preforming graphene sheets orderly and dispersedly, would replace graphene nanosheets in polymer nanocomposite reinforcement and endow composites with unique structure and some unexpected performance.

  3. Mechanical behavior of polyester-based woven jute/glass hybrid composites

    NASA Astrophysics Data System (ADS)

    Ahsan, Q.; Tanju, S.

    2012-06-01

    In polymer composite fabrication system, hybridization of jute fibers with synthetic fibers is one of the techniques adopted to overcome some of the limitations (poor mechanical properties and moisture resistance) that have been identified for jute fiber reinforced composites. In the present study, the effect of hybridization on mechanical properties of jute and glass mat reinforced polyester composites has been evaluated experimentally. The composites were made of glass mat, jute mat and varying layers of jute and glass mat in the polyester matrix by applying hand lay-up technique at room temperature (250C). The values of mechanical properties obtained from tensile, flexural and interlaminar shear strength (ILSS) tests show significant improvement with the increase of glass fiber content in hybrid composites. But the positive contribution from glass mat in increasing of ILSS of composite is limited to some extent and the optimum ILSS is achieved when glass-jute incorporated in composite as 50-50 weight basis. SEM images were used to study the modes of fracture, fiber-matrix adhesion, and jute-glass layer adhesion. The fracture surfaces resulted from different tests clearly show that cracks propagate throughout the polyester matrix by tearing the jute mat and delaminating the glass mat.

  4. Repairable Woven Carbon Fiber Composites with Full Recyclability Enabled by Malleable Polyimine Networks.

    PubMed

    Taynton, Philip; Ni, Huagang; Zhu, Chengpu; Yu, Kai; Loob, Samuel; Jin, Yinghua; Qi, H Jerry; Zhang, Wei

    2016-04-20

    Carbon-fiber reinforced composites are prepared using catalyst-free malleable polyimine networks as binders. An energy neutral closed-loop recycling process has been developed, enabling recovery of 100% of the imine components and carbon fibers in their original form. Polyimine films made using >21% recycled content exhibit no loss of mechanical performance, therefore indicating all of the thermoset composite material can be recycled and reused for the same purpose.

  5. Mars Mission Research Center: Research in 3-D braiding

    SciTech Connect

    Reid, R.L.; El-Shiekh, A.

    1995-06-01

    Textile reinforcements are a growing area in the field of composite materials. At the Mars Mission Research Center`s 3-D braiding laboratory researchers are investigating methods of machine automation and new structural geometries. Advances in machine automation are leading to increased production rates and higher quality products. The development of the 6-step process creates a fabric that incorporates the x-y-z structure within a 4-step braid. Physical testing of braided composites includes traditional static test methods as well as bearing, thread strength, and damage tolerance. With the recent acquisition of a 288 carrier 2-D braider, researchers are conducting more comparison studies between composites reinforced with 3-D structures and those made of 2-D fabrics (uniaxial, woven, and 2-D braids).

  6. Comparative Studies on the Mechanical Properties of Nonwoven- and Woven-Flax-Fiber-Reinforced Poly(Butylene Adipate-Co-Terephthalate)-Based Composite Laminates

    NASA Astrophysics Data System (ADS)

    Phongam, N.; Dangtungee, R.; Siengchin, S.

    2015-03-01

    Textile biocomposites made from woven- and nonwoven-flax-fiber-reinforced poly(butylene adipate-co-terephthalate) (PBAT) were prepared by compression molding using the film stacking method, and their tensile strength and stiffness, flexural strength and modulus, and impact strength were determined experimentally. The PBAT-based composites were subjected to water absorption tests. The mechanical properties of pure PBAT and the textile composites were compared, and the influence of flax weave styles on the properties were evaluated. The biocomposite reinforced with 4 × 4-plain weave fibers showed the highest strength and stiffness compared with those of the other textile biocomposites and pure PBAT.

  7. Ballistic impact behaviour of woven fabric composite: Finite element analysis and experiments

    NASA Astrophysics Data System (ADS)

    Phadnis, V. A.; Pandya, K. S.; Naik, N. K.; Roy, A.; Silberschmidt, V. V.

    2013-07-01

    A mechanical behaviour of plain-weave E-glass fabric/epoxy laminate composite plate exposed to ballistic impact is studied using a finite-element (FE) code Abaqus/Explicit. A ply-level FE model is developed, where a fabric-reinforced ply is modelled as a homogeneous orthotropic elastic material with potential to sustain progressive stiffness degradation due to fiber/matrix cracking, and plastic deformation under shear loading. The model is implemented as a VUMAT user subroutine. Ballistic experiments were carried out to validate the FE model. A parametric study for varying panel thickness is performed to compare impact resistance of the studied composite.

  8. Multi-scale Characterisation of the 3D Microstructure of a Thermally-Shocked Bulk Metallic Glass Matrix Composite

    PubMed Central

    Zhang, Wei; Bodey, Andrew J.; Sui, Tan; Kockelmann, Winfried; Rau, Christoph; Korsunsky, Alexander M.; Mi, Jiawei

    2016-01-01

    Bulk metallic glass matrix composites (BMGMCs) are a new class of metal alloys which have significantly increased ductility and impact toughness, resulting from the ductile crystalline phases distributed uniformly within the amorphous matrix. However, the 3D structures and their morphologies of such composite at nano and micrometre scale have never been reported before. We have used high density electric currents to thermally shock a Zr-Ti based BMGMC to different temperatures, and used X-ray microtomography, FIB-SEM nanotomography and neutron diffraction to reveal the morphologies, compositions, volume fractions and thermal stabilities of the nano and microstructures. Understanding of these is essential for optimizing the design of BMGMCs and developing viable manufacturing methods. PMID:26725519

  9. Multi-scale Characterisation of the 3D Microstructure of a Thermally-Shocked Bulk Metallic Glass Matrix Composite

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Bodey, Andrew J.; Sui, Tan; Kockelmann, Winfried; Rau, Christoph; Korsunsky, Alexander M.; Mi, Jiawei

    2016-01-01

    Bulk metallic glass matrix composites (BMGMCs) are a new class of metal alloys which have significantly increased ductility and impact toughness, resulting from the ductile crystalline phases distributed uniformly within the amorphous matrix. However, the 3D structures and their morphologies of such composite at nano and micrometre scale have never been reported before. We have used high density electric currents to thermally shock a Zr-Ti based BMGMC to different temperatures, and used X-ray microtomography, FIB-SEM nanotomography and neutron diffraction to reveal the morphologies, compositions, volume fractions and thermal stabilities of the nano and microstructures. Understanding of these is essential for optimizing the design of BMGMCs and developing viable manufacturing methods.

  10. Versatile Method for Producing 2D and 3D Conductive Biomaterial Composites Using Sequential Chemical and Electrochemical Polymerization.

    PubMed

    Severt, Sean Y; Ostrovsky-Snider, Nicholas A; Leger, Janelle M; Murphy, Amanda R

    2015-11-18

    Flexible and conductive biocompatible materials are attractive candidates for a wide range of biomedical applications including implantable electrodes, tissue engineering, and controlled drug delivery. Here, we demonstrate that chemical and electrochemical polymerization techniques can be combined to create highly versatile silk-conducting polymer (silk-CP) composites with enhanced conductivity and electrochemical stability. Interpenetrating silk-CP composites were first generated via in situ deposition of polypyrrole during chemical polymerization of pyrrole. These composites were sufficiently conductive to serve as working electrodes for electropolymerization, which allowed an additional layer of CP to be deposited on the surface. This sequential method was applied to both 2D films and 3D sponge-like silk scaffolds, producing conductive materials with biomimetic architectures. Overall, this two-step technique expanded the range of available polymers and dopants suitable for the synthesis of mechanically robust, biocompatible, and highly conductive silk-based materials.

  11. 3D finite element modelling of guided wave scattering at delaminations in composites

    NASA Astrophysics Data System (ADS)

    Murat, Bibi Intan Suraya; Fromme, Paul

    2016-02-01

    Carbon fiber laminate composites are increasingly used for aerospace structures as they offer a number of advantages including a good strength to weight ratio. However, impact during the operation and servicing of the aircraft can lead to barely visible and difficult to detect damage. Depending on the severity of the impact, delaminations can occur, reducing the load carrying capacity of the structure. Efficient nondestructive testing of composite panels can be achieved using guided ultrasonic waves propagating along the structure. The guided wave (A0 Lamb wave mode) scattering at delaminations was modeled using full three-dimensional Finite Element (FE) simulations. The influence of the delamination size was systematically investigated from a parameter study. A significant influence of the delamination width on the guided wave scattering was found, especially on the angular dependency of the scattered guided wave amplitude. The sensitivity of guided ultrasonic waves for the detection of delamination damage in composite panels is discussed.

  12. The high velocity impact loading on symmetrical and woven hybrid composite laminates

    NASA Astrophysics Data System (ADS)

    Jin, Martin; Richardson, Mel; Zhang, Zhong Yi

    2007-07-01

    Space structures use fibre composite materials, due to their lightweight. This paper examines the impact response of symmetrical and hybrid composite laminates. Special attention is given to the stacking sequences used. The experimental study of structures has always provided a major contribution to our understanding. Even with the formidable growth in the use and capacity of computing power the need for experimental measurement is as compelling as ever. The design of hybrid composite structures is complicated by the number of design variables and the interaction of the constituents is the composite system. Since it is desirable to experimentally test the design and it is not practical to test a full scale model, the structural/material similitude concept is used to create a small scale model with a similar structural response. In the current study, experimental investigations were carried out to determine the response of four different combinations of hybrid laminates to low-velocity impact loading using an instrumented impact testing machine. Hybrid laminates were fabricated with twill weave carbon fabric and plain weave S2-glass fabric using vacuum assisted resin molding process with SC-15 epoxy resin system. Response of carbon/epoxy and glass/epoxy laminates was also investigated to compare with that of hybrid samples. Square laminates of size 100 mm and nominal thickness of 3 mm were subjected to low-velocity impact loading at four energy levels of 10, 20, 30 and 40 J. Results of the study indicate that there is considerable improvement in the load carrying capability of hybrid composites as compared to carbon/epoxy laminates with slight reduction in stiffness.

  13. Recipe for High Moment Materials with Rare-earth and 3d Transition Metal Composites

    NASA Astrophysics Data System (ADS)

    Autieri, Carmine; Kumar, P. Anil; Walecki, Dirk; Webers, Samira; Gubbins, Mark A.; Wende, Heiko; Sanyal, Biplab

    2016-07-01

    Materials with high volume magnetization are perpetually needed for the generation of sufficiently large magnetic fields by writer pole of magnetic hard disks, especially for achieving increased areal density in storage media. In search of suitable materials combinations for this purpose, we have employed density functional theory to predict the magnetic coupling between iron and gadolinium layers separated by one to several monolayers of 3d transition metals (Sc-Zn). We demonstrate that it is possible to find ferromagnetic coupling for many of them and in particular for the early transition metals giving rise to high moment. Cr and Mn are the only elements able to produce a significant ferromagnetic coupling for thicker spacer layers. We also present experimental results on two trilayer systems Fe/Sc/Gd and Fe/Mn/Gd. From the experiments, we confirm a ferromagnetic coupling between Fe and Gd across a 3 monolayers Sc spacer or a Mn spacer thicker than 1 monolayer. In addition, we observe a peculiar dependence of Fe/Gd magnetic coupling on the Mn spacer thickness.

  14. Recipe for High Moment Materials with Rare-earth and 3d Transition Metal Composites

    PubMed Central

    Autieri, Carmine; Kumar, P. Anil; Walecki, Dirk; Webers, Samira; Gubbins, Mark A.; Wende, Heiko; Sanyal, Biplab

    2016-01-01

    Materials with high volume magnetization are perpetually needed for the generation of sufficiently large magnetic fields by writer pole of magnetic hard disks, especially for achieving increased areal density in storage media. In search of suitable materials combinations for this purpose, we have employed density functional theory to predict the magnetic coupling between iron and gadolinium layers separated by one to several monolayers of 3d transition metals (Sc-Zn). We demonstrate that it is possible to find ferromagnetic coupling for many of them and in particular for the early transition metals giving rise to high moment. Cr and Mn are the only elements able to produce a significant ferromagnetic coupling for thicker spacer layers. We also present experimental results on two trilayer systems Fe/Sc/Gd and Fe/Mn/Gd. From the experiments, we confirm a ferromagnetic coupling between Fe and Gd across a 3 monolayers Sc spacer or a Mn spacer thicker than 1 monolayer. In addition, we observe a peculiar dependence of Fe/Gd magnetic coupling on the Mn spacer thickness. PMID:27381456

  15. LiFePO4 - 3D carbon nanofiber composites as cathode materials for Li-ions batteries

    NASA Astrophysics Data System (ADS)

    Dimesso, L.; Spanheimer, C.; Jaegermann, W.; Zhang, Y.; Yarin, A. L.

    2012-03-01

    The characterization of carbon nanofiber 3D nonwovens, prepared by electrospinning process, coated with olivine structured lithium iron phosphate is reported. The LiFePO4 as cathode material for lithium ion batteries was prepared by a Pechini-assisted reversed polyol process. The coating has been successfully performed on carbon nanofiber 3D nonwovens by soaking in aqueous solution containing lithium, iron salts and phosphates at 70 °C for 2-4 h. After drying-out, the composites were annealed at 600 °C for 5 h under nitrogen. The surface investigation of the prepared composites showed a uniform coating of the carbon nonwoven nanofibers as well as the formation of cauliflower-like crystalline structures which are uniformly distributed all over the surface area of the carbon nanofibers. The electrochemical measurements on the composites showed good performances delivering a discharge specific capacity of 156 mAhg- 1 at a discharging rate of C/25 and 152 mAhg- 1 at a discharging rate of C/10 at room temperature.

  16. Fatigue resistance of unnotched and post impact(+/- 30 deg/0 deg) 3-D braided composites. Final report

    SciTech Connect

    Portanova, M.A.

    1994-01-01

    The fatigue resistance of a multiaxial braided (3-D) graphite/expoxy composite in both unnotched and post impacted conditions has been evaluated. The material tested is a (+/- 30/0 deg) multiaxial braid constructed from AS4/12K tow graphite fibers and British Petroleum E905L epoxy resin. These materials were braided as dry preforms and the epoxy was added using a resin transfer molding process (RTM). The unnotched and post-impact specimens were tested in compression-compression fatigue at 10 Hz with a stress ratio of R=10. The unnotched tension-tension fatigue specimens were tested at S Hz with a stress ration of R=0.1. Damage initiation and growth was documented through the application of radiography and ultrasonic through transmission (C-scans). Visible inspection of surface and edge damage was also noted to describe the initiation and progression of damage in these materials. The mechanisms leading to damage initiation were established and failure modes were determined. Stiffness and strength degradation were measured as a function of applied cycles. These 3-D braided composite results were compared to strain levels currently used to design primary structure in commercial aircraft composite components made from prepreg tape and autoclave cured.

  17. Tri-color composite volume H-PDLC grating and its application to 3D color autostereoscopic display.

    PubMed

    Wang, Kangni; Zheng, Jihong; Gao, Hui; Lu, Feiyue; Sun, Lijia; Yin, Stuart; Zhuang, Songlin

    2015-11-30

    A tri-color composite volume holographic polymer dispersed liquid crystal (H-PDLC) grating and its application to 3-dimensional (3D) color autostereoscopic display are reported in this paper. The composite volume H-PDLC grating consists of three different period volume H-PDLC sub-gratings. The longer period diffracts red light, the medium period diffracts the green light, and the shorter period diffracts the blue light. To record three different period gratings simultaneously, two photoinitiators are employed. The first initiator consists of methylene blue and p-toluenesulfonic acid and the second initiator is composed of Rose Bengal and N-phenyglycine. In this case, the holographic recording medium is sensitive to entire visible wavelengths, including red, green, and blue so that the tri-color composite grating can be written simultaneously by harnessing three different color laser beams. In the experiment, the red beam comes from a He-Ne laser with an output wavelength of 632.8 nm, the green beam comes from a Verdi solid state laser with an output wavelength of 532 nm, and the blue beam comes from a He-Cd laser with an output wavelength of 441.6 nm. The experimental results show that diffraction efficiencies corresponding to red, green, and blue colors are 57%, 75% and 33%, respectively. Although this diffraction efficiency is not perfect, it is high enough to demonstrate the effect of 3D color autostereoscopic display.

  18. The effect of shock wave impingement on thin, woven glass fiber reinforced, polymer composite plates

    NASA Astrophysics Data System (ADS)

    Jahnke, Douglas M.

    High-performance fiber-reinforced polymer (FRP) composites have been increasingly used in many applications over the last 30 years. Their high specific stiffness, specific strength, and energy absorption capacity have made them attractive as replacements for traditional materials. While the dynamic response of homogeneous or monolithic materials has been well documented, the response of FRP composites is still under investigation. Knowledge of the response of FRP composites under this type of loading is essential to evaluating its performance as a structural or protective material. While such information starts to be slowly available, the effects of dynamic thermomechanical extremes such as shock wave loading on the FRP composites is relatively unknown. The challenge then is to develop a consistent laboratory methodology that allows investigations of the interactions between a FRP composite and a shock wave and eventually testing of such materials for performance evaluations under shock loading. Measuring the deformation of test specimens caused by shock wave impingement of different intensities was basic to understanding the gross effects on the FRP composites. In early tests, displacement across the diameter of the test specimen was measured after the end of the test giving a static measurement of the permanent deformation. To allow meaningful comparisons between disparate materials subject to different shock wave intensities a method of weighting and normalizing the was developed. The complexity of setting up and running a shock wave test limited the number tests could be performed, so while the results aren't statically robust, the trends observed are useful in comparing or choosing among different materials. A Time-Resolved Catadioptric Stereo Digital Image Correlation (TRC-SDIC) technique was developed which provide a non-contact, full-field method of measuring deformation over the time span from the impingement of the shock wave including the maximum

  19. A comprehensive study of woven carbon fiber-reinforced nylon 6 composites

    NASA Astrophysics Data System (ADS)

    Pillay, Selvum

    Liquid molding of thermoset composites has become very popular in all industry sectors, including aerospace, automotive, mass transit, and sporting goods, but the cost of materials and processing has limited the use to high-end applications. Thermoplastic composites are relatively cheap; however, the use has been limited to components with short fiber reinforcing. The high melt viscosity and short processing window precludes their use in the liquid molding of large structures and applications with continuous fiber reinforcement. The current research addresses the processing parameters, methodology, and limitations of vacuum assisted resin transfer molding (VARTM) of carbon fabric-reinforced, thermoplastic polyamide 6 (PA6). The material used is casting grade PA6. The process developed for using VARTM to produce carbon fabric-reinforced PA6 composites is explained in detail. The effects of infusion temperature and flow distance on the fiber weight fraction and crystallinity of the PA6 resin are presented. The degree of conversion from monomer to polymer was determined. Microscopic studies to show the wet-out of the fibers at the filament level are also presented. Tensile, flexural, short beam shear strength (SBSS), and low-velocity impact test results are presented and compared to a equivalent thermoset matrix composite. The rubber toughened epoxy system (SC-15) was chosen for the comparative study because the system has been especially developed to overcome the brittle nature of epoxy composites. The environmental effects of moisture and ultraviolet (UV) radiation on the carbon/nylon 6 composite were investigated. The samples were immersed in boiling water for 100 hr, and mechanical tests were conducted. Results showed that moisture causes plasticization of the matrix and attacks the fiber matrix interface. This leads to deterioration of the mechanical properties. The samples were also exposed to UV for up to 600 hr, and post exposure tests were conducted. The

  20. 3D modelling of squeeze flow of unidirectional and fabric composite inserts

    NASA Astrophysics Data System (ADS)

    Ghnatios, Chady; Abisset-Chavanne, Emmanuelle; Chinesta, Francisco; Keunings, Roland

    2016-10-01

    The enhanced design flexibility provided to the thermo-forming of thermoplastic materials arises from the use of both continuous and discontinuous thermoplastic prepregs. Discontinuous prepregs are patches used to locally strengthen the part. In this paper, we propose a new modelling approach for suspensions involving composite patches that uses theoretical concepts related to discontinuous fibres suspensions, transversally isotropic fluids and extended dumbbell models.

  1. Microstructure of 3D-Printed Polymer Composites Investigated by Small-Angle Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Kang, Tae Hui; Compton, Brett G.; Heller, William T.; Urban, Voker S.; Duty, Chad E.; Do, Changwoo

    Polymer composites printed from the large scale printer at Manufacturing Demonstration Facility at Oak Ridge National Laboratory have been investigated by small-angle neutron scattering (SANS). For the Acrylonitrile Butadiene Styrene (ABS)/Carbon Fiber (CF) composites, the microstructure of polymer domains and the alignment of CF have been characterized across the layer from the printed piece. CF shows strong anisotropic alignment along the printing direction due to the flow of polymer melt at the nozzle. Order parameter of the anisotropy which ranges from -0.11 to -0.06 exhibits strong correlation with the position within the layer: stronger alignment near the layer interface. It is also confirmed that the existence of CF reduces the polymer domain correlation length significantly and reinforces the mechanical strength of the polymer composites. For the Epoxy/nano-clay platelet composites, the effect of processing condition, nozzle size, and the addition of the another filler, Silicon Carbide (SC), have been investigated by SANS. Nano-clay platelet shows strong anisotropic alignment along the printing direction as well. Order parameter of the anisotropy varies according to nozzle size and presence of the SC, and difference disappears at high Q region. Scientific User Facilities Division and Materials Sciences and Energy Division, Office of Basic Energy Sciences, U.S. Department of Energy.

  2. Effects of Nesting on Compression-Loaded 2-D Woven Textile Composites

    NASA Technical Reports Server (NTRS)

    Adams, Daniel OHare; Breiling, Kurtis B.; Verhulst, Mark A.

    1995-01-01

    Layer nesting was investigated in five harness satin weave textile composite laminates under static compression loading. Two carbon/epoxy material systems, AS4/3501-6 and IM7/8551-7A were considered. Laminates were fabricated with three idealized nesting cases: stacked, split-span and diagonal. Similar compression strength reductions due to the effects of idealized nesting were identified for each material. The diagonal nesting geometry produced the largest reduction in static strength when compared to the compression strength of a conventional textile composite. All three nesting cases produced reductions in strength and ultimate strain due to the effects of idealized nesting. Finite element results showed consistent strength reduction trends for the idealized nesting cases, however the magnitudes of compressive strengths were overpredicted.

  3. Characterization of E-glass/polyester woven fabric composite laminates and tubes

    SciTech Connect

    Guess, T.R.; Reedy, E.D. Jr.; Stavig, M.E.

    1995-12-01

    This report describes an experimental study that supported the LDRD program ``A General Approach for Analyzing Composite Structures``. The LDRD was a tightly coupled analytical / experimental effort to develop models for predicting post-yield progressive failure in E-glass fabric/polyester composites subjected to a variety of loading conditions. Elastic properties, fracture toughness parameters, and failure responses were measured on flat laminates, rings and tubes to support the development and validation of material and structural models. Test procedures and results are presented for laminates tested in tension, compression, flexure, short beam shear, double cantilever beam Mode I fracture toughness, and end notched flexure Mode II fracture toughness. Structural responses, including failure, of rings loaded in diametral compression and tubes tested in axial compression, are also documented.

  4. Measurement and Prediction of Effective Thermal Conductivity for Woven Fabric Composites

    NASA Astrophysics Data System (ADS)

    Goo, Nam Seo; Woo, Kyeongsik

    The current paper deals with the measurement and prediction of thermal conductivities for plain weave fabric composites. An experimental apparatus was setup to measure the temperature gradients from which the thermal conductivities were obtained. The thermal conductivities were also calculated using finite element analyses for plain weave unit cell models and then compared with experimental results. In addition, the effect of a phase shift and the fiber volume fraction in the tow on the thermal conductivities was addressed.

  5. A micromechanical model for the failure and damage assessment of woven composites

    NASA Astrophysics Data System (ADS)

    Abdelrahman, Wael Gamal Eldin

    A micromechanical model is advanced in order to study the stress transfer and associated damage and failure in classes of conventional and textile type fibrous composites. Unidirectionally reinforced matrix with straight and undulated fibers define the repeating constructing cell for conventional and textile composites, respectively. Starting with the case of straight reinforcement, we approximate and model the actual discrete composite as a concentric cylindrical system. For axisymmetric loading, and upon adopting some appropriate restrictions on the radial behavior of some field quantities, an elasticity-based procedure reduces the two-dimensional field equations, which hold in both fiber and matrix components together with the appropriate interface, symmetry and boundary conditions, to a quasi-one-dimensional system. This analysis is further extended to cases involving undulated fibers. Based upon local directions (slopes) of the undulated fibers, the linear transformation is used to obtain local stress distributions along the undulated fibers. The total stress field is found to be combinations of these local stresses and the inherent contributions obtained from the transformations of the normal loads along the undulated directions in the absence of reinforcement. This simple system retains total account of the system's physics and presents itself in the form of coupled partial differential equations in the longitudinal displacements and stresses of both the fiber and matrix components. According to this model, damage is simulated in the form of stress free boundary conditions. Perpetuation of damage is based upon the maximum normal stress criterion. The adverse effect of such damage on the stiffness properties of the composite is predicted. Results show the favorable effect of undulation in decreasing the rate of property degradation with increasing damage. The model is quite general and has been applied to several situations. These include response to static

  6. Experimental and Numerical Analysis of Damage in Woven GFRP Composites Under Large-deflection Bending

    NASA Astrophysics Data System (ADS)

    Ullah, Himayat; Harland, Andy R.; Silberschmidt, Vadim V.

    2012-10-01

    Textile-reinforced composites such as glass fibre-reinforced polymer (GFRP) used in sports products can be exposed to different in-service conditions such as large bending deformation and multiple impacts. Such loading conditions cause high local stresses and strains, which result in multiple modes of damage and fracture in composite laminates due to their inherent heterogeneity and non-trivial microstructure. In this paper, various damage modes in GFRP laminates are studied using experimental material characterisation, non-destructive micro-structural damage evaluation and numerical simulations. Experimental tests are carried out to characterise the behaviour of these materials under large-deflection bending. To obtain in-plane shear properties of laminates, tensile tests are performed using a full-field strain-measurement digital image correlation technique. X-ray micro computed tomography (Micro CT) is used to investigate internal material damage modes - delamination and cracking. Two-dimensional finite element (FE) models are implemented in the commercial code Abaqus to study the deformation behaviour and damage in GFRP. In these models, multiple layers of bilinear cohesive-zone elements are employed to study the onset and progression of inter-ply delamination and intra-ply fabric fracture of composite laminate, based on the X-ray Micro CT study. The developed numerical models are capable to simulate these features with their mechanisms as well as subsequent mode coupling observed in tests and Micro CT scanning. The obtained results of simulations are in agreement with experimental data.

  7. A nondestructive experimental study on damage progression in woven glass-epoxy composites

    NASA Astrophysics Data System (ADS)

    Pollock, Patrick; Yu, Lingyu; Guo, Siming; Sutton, Michael

    2011-04-01

    The purpose of this study is to develop a better understanding of the damage progression in composite materials undergoing tension loading, while pushing the boundaries on measurements to identify material damage. Several SHM methods are used to detect the types of damage that are observed in each test. A Digital Image Correlation system is used to measure the surface strain throughout the test and also the residual strain after each loading cycle. The residual strain is used as an indicator for the presence of damage in the structure. Piezoelectric wafer active sensors (PWAS) are bonded to the composite material and are used to detect damage using Electromechanical Impedance Spectroscopy (EMIS). The EMIS method analyzes the changes in the structural resonances and anti-resonances. The Electrochemical Impedance Spectroscopy (ECIS) method is also used to detect damage. This method uses the impedance of the structure to determine the state of the structure. As the damage progresses in the composite, the impedance across the thickness will change.

  8. Recycling of woven carbon-fibre-reinforced polymer composites using supercritical water.

    PubMed

    Knight, Chase C; Zeng, Changchun; Zhang, Chuck; Wang, Ben

    2012-01-01

    Over the past few years, there has been great deal of interest in recycling carbon-fibre-reinforced polymer composites. One method that has shown promising results involves the use of supercritical fluids to achieve separation between matrix and fibres by effectively degrading the resin into lower molecular weight compounds. In addition, the solvents used are environmentally benign and can also be recovered and reused. In this study, supercritical water with 0.05 M KOH as the catalyst was used for the recycling of an aerospace-grade high-performance epoxy carbon fibre composite (Hexcel 8552/IM7). The morphology of the reclaimed fibres was observed by scanning electron microscopy, and the tensile properties of the fibres were measured by single filament testing. The effects of processing time on the resin elimination efficiency and fibre property retention were investigated. With the process developed in this research, as much as 99.2 wt% resin elimination was achieved, resulting in the recovery of clean, undamaged fibres. The reclaimed fibres retained the original tensile strength. The feasibility of recycling multiple layer composites was also explored.

  9. 3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties

    PubMed Central

    Lewicki, James P.; Rodriguez, Jennifer N.; Zhu, Cheng; Worsley, Marcus A.; Wu, Amanda S.; Kanarska, Yuliya; Horn, John D.; Duoss, Eric B.; Ortega, Jason M.; Elmer, William; Hensleigh, Ryan; Fellini, Ryan A.; King, Michael J.

    2017-01-01

    Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignment within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Furthermore, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response. PMID:28262669

  10. 3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties

    NASA Astrophysics Data System (ADS)

    Lewicki, James P.; Rodriguez, Jennifer N.; Zhu, Cheng; Worsley, Marcus A.; Wu, Amanda S.; Kanarska, Yuliya; Horn, John D.; Duoss, Eric B.; Ortega, Jason M.; Elmer, William; Hensleigh, Ryan; Fellini, Ryan A.; King, Michael J.

    2017-03-01

    Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignment within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Furthermore, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response.

  11. 3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties.

    PubMed

    Lewicki, James P; Rodriguez, Jennifer N; Zhu, Cheng; Worsley, Marcus A; Wu, Amanda S; Kanarska, Yuliya; Horn, John D; Duoss, Eric B; Ortega, Jason M; Elmer, William; Hensleigh, Ryan; Fellini, Ryan A; King, Michael J

    2017-03-06

    Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignment within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Furthermore, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response.

  12. Tensile Stress Rupture Behavior of a Woven Ceramic Matrix Composite in Humid Environments at Intermediate Temperature

    DTIC Science & Technology

    2005-03-01

    for Structural Ceramic Matrix Composites.” Proceedings of CIMTEC ’02, Florence, Italy (2002). 29. L.P. Zawada . Senior Materials Research...Washington D.C., 1998 and 2000. 31. L.P. Zawada . Senior Materials Research Engineer, Air Force Research Laboratory, Materials and Manufacturing...STP 1309, Eds. M.G. Jenkins, S.T. Gonczy, E. Lara-Curzio, N.E. Ashbaugh, and L.P. Zawada (1997). 43. H.T. Lin, P.F. Becher, and P.F. Tortorelli

  13. A mapping of an ensemble of mitochondrial sequences for various organisms into 3D space based on the word composition.

    PubMed

    Aita, Takuyo; Nishigaki, Koichi

    2012-11-01

    To visualize a bird's-eye view of an ensemble of mitochondrial genome sequences for various species, we recently developed a novel method of mapping a biological sequence ensemble into Three-Dimensional (3D) vector space. First, we represented a biological sequence of a species s by a word-composition vector x(s), where its length [absolute value]x(s)[absolute value] represents the sequence length, and its unit vector x(s)/[absolute value]x(s)[absolute value] represents the relative composition of the K-tuple words through the sequence and the size of the dimension, N=4(K), is the number of all possible words with the length of K. Second, we mapped the vector x(s) to the 3D position vector y(s), based on the two following simple principles: (1) [absolute value]y(s)[absolute value]=[absolute value]x(s)[absolute value] and (2) the angle between y(s) and y(t) maximally correlates with the angle between x(s) and x(t). The mitochondrial genome sequences for 311 species, including 177 Animalia, 85 Fungi and 49 Green plants, were mapped into 3D space by using K=7. The mapping was successful because the angles between vectors before and after the mapping highly correlated with each other (correlation coefficients were 0.92-0.97). Interestingly, the Animalia kingdom is distributed along a single arc belt (just like the Milky Way on a Celestial Globe), and the Fungi and Green plant kingdoms are distributed in a similar arc belt. These two arc belts intersect at their respective middle regions and form a cross structure just like a jet aircraft fuselage and its wings. This new mapping method will allow researchers to intuitively interpret the visual information presented in the maps in a highly effective manner.

  14. 77 FR 32938 - Narrow Woven Ribbons With Woven Selvedge From Taiwan: Preliminary Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-04

    ... the manufacture of typewriter or printer ribbons; (5) Narrow woven labels and apparel tapes, cut-to... States, 337 F.3d 1373, 1382-83 (Fed. Cir. 2003) (Nippon). We preliminarily find that Hubschercorp did not... respect to this company. See Nippon, 337 F.3d at 1382-83. Selection of the AFA Rate Section 776(b) of...

  15. In-process 3D laser measurement to control the fiber tape-laying for composite production

    NASA Astrophysics Data System (ADS)

    Schmitt, Robert; Mersmann, Christoph; Damm, Björn

    2010-05-01

    Metrology is the key to an economically feasible production of fiber-reinforced composites in the field of automated tape laying, applying a novel laser light-section sensor system (LLSS) to measure process quality and feed back the results to close control loops of the production system. The developed method derives 3D measurements from height profiles through an in-process surface scan by the integrated LLSS. Gaps, overlaps, misalignment and defects of the composite tapes are detected during their lay-up and consolidation by comparing the measurement results with a CAD/CAM model of the lay-up. The height profiles are processed with a novel algorithm based on a non-linear least-square fitting to a set of sigmoid functions to ensure sub-pixel accuracy.

  16. Fabrication of porous 3D flower-like Ag/ZnO heterostructure composites with enhanced photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Liang, Yimai; Guo, Na; Li, Linlin; Li, Ruiqing; Ji, Guijuan; Gan, Shucai

    2015-03-01

    Porous 3D flower-like Ag/ZnO heterostructural composites were fabricated by hydrothermal and photochemical deposition methods, without using any pore-directing reagents and surfactants. The obtained samples were characterized by XRD, SEM, TEM, XPS, BJH, DRS, and PL spectrum. The experiment results show that the silver nanoparticles successfully load on the surface of assembled ZnO flowers. The TEM and SEM morphologies demonstrated unique porous 3D flower-like structure of Ag/ZnO. Such special structure makes larger surface area and more active sites exposed during the reaction, facilitating the transportation of reactants and products and increasing the reaction rate. The photocatalytic degradation experiments under UV irradiation using Rhodamine B (RhB) as a model dye were executed. The relative results demonstrate that the photocatalytic activity of Ag/ZnO is obviously improved compared with the pure ZnO and the commercial TiO2 (Degussa P25), the AZ-15 sample has the highest photocatalytic activity. The Ag/ZnO heterostructure composites promoted the separation of photo-induced electrons and holes, which was proved by photoluminescence spectra (PL).

  17. 3D Printing of Aniline Tetramer-Grafted-Polyethylenimine and Pluronic F127 Composites for Electroactive Scaffolds.

    PubMed

    Dong, Shi-Lei; Han, Lu; Du, Cai-Xia; Wang, Xiao-Yu; Li, Lu-Hai; Wei, Yen

    2017-02-01

    Electroactive hydrogel scaffolds are fabricated by the 3D-printing technique using composites of 30% Pluronic F127 and aniline tetramer-grafted-polyethylenimine (AT-PEI) copolymers with various contents from 2.5% to 10%. The synthesized AT-PEI copolymers can self-assemble into nanoparticles with the diameter of ≈50 nm and display excellent electroactivity due to AT conjugation. The copolymers are then homogeneously distributed into 30% Pluronic F127 solution by virtue of the thermosensitivity of F127, denoted as F/AT-PEI composites. Macroscopic photographs of latticed scaffolds elucidate their excellent printability of F/AT-PEI hydrogels for the 3D-printing technique. The conductivities of the printed F/AT-PEI scaffolds are all higher than 2.0 × 10(-3) S cm(-1) , which are significantly improved compared with that of F127 scaffold with only 0.94 × 10(-3) S cm(-1) . Thus, the F/AT-PEI scaffolds can be considered as candidates for application in electrical stimulation of tissue regeneration such as repair of muscle and cardiac nerve tissue.

  18. Effects of Microstructural Variability on Thermo-Mechanical Properties of a Woven Ceramic Matrix Composite

    NASA Technical Reports Server (NTRS)

    Goldsmith, Marlana B.; Sankar, Bhavani V.; Haftka, Raphael T.; Goldberg, Robert K.

    2013-01-01

    The objectives of this paper include identifying important architectural parameters that describe the SiC/SiC five-harness satin weave composite and characterizing the statistical distributions and correlations of those parameters from photomicrographs of various cross sections. In addition, realistic artificial cross sections of a 2D representative volume element (RVE) are generated reflecting the variability found in the photomicrographs, which are used to determine the effects of architectural variability on the thermo-mechanical properties. Lastly, preliminary information is obtained on the sensitivity of thermo-mechanical properties to architectural variations. Finite element analysis is used in combination with a response surface and it is shown that the present method is effective in determining the effects of architectural variability on thermo-mechanical properties.

  19. Impact of Material and Architecture Model Parameters on the Failure of Woven Ceramic Matrix Composites (CMCs) via the Multiscale Generalized Method of Cells

    NASA Technical Reports Server (NTRS)

    Liu, Kuang C.; Arnold, Steven M.

    2011-01-01

    It is well known that failure of a material is a locally driven event. In the case of ceramic matrix composites (CMCs), significant variations in the microstructure of the composite exist and their significance on both deformation and life response need to be assessed. Examples of these variations include changes in the fiber tow shape, tow shifting/nesting and voids within and between tows. In the present work, the effects of many of these architectural parameters and material scatter of woven ceramic composite properties at the macroscale (woven RUC) will be studied to assess their sensitivity. The recently developed Multiscale Generalized Method of Cells methodology is used to determine the overall deformation response, proportional elastic limit (first matrix cracking), and failure under tensile loading conditions. The macroscale responses investigated illustrate the effect of architectural and material parameters on a single RUC representing a five harness satin weave fabric. Results shows that the most critical architectural parameter is weave void shape and content with other parameters being less in severity. Variation of the matrix material properties was also studied to illustrate the influence of the material variability on the overall features of the composite stress-strain response.

  20. Properties and modification of porous 3-D collagen/hydroxyapatite composites.

    PubMed

    Sionkowska, A; Kozłowska, J

    2013-01-01

    A freeze drying technique was used to form porous three-dimensional collagen matrixes modified by the addition of a variable amount of nano-hydroxyapatite. For chemical cross-linking EDC/NHS were used. Physical cross-linking was achieved by dehydrothermal treatment. Mechanical properties, morphology, dissolution, porosity, density, enzymatic degradation and swelling properties of materials have been studied after cross-linking. The density of scaffolds and its compressive modulus increased with an increasing amount of hydroxyapatite and collagen concentration in the composite scaffold, while the swelling ratio and porosity decreased. The studied scaffolds dissolved slowly in PBS solution. DHT cross-linked collagen matrices showed a much faster degradation rate after exposure to collagenase than the EDC cross-linked samples.

  1. Developing a confocal acoustic holography microscope for non-invasive 3D temperature and composition measurements.

    PubMed

    Herring, Rodney A; Jacquemin, Peter; Sawicka, Barbara D; Atalick, Stefan

    2009-06-01

    A confocal acoustic holography microscope (CAHM) has been designed, simulated and partially verified experimentally to take holograms for non-invasive, three-dimensional measurements of a specimen's refractive indices from one view point. The designed and simulated prototype CAHM used a frequency of 2.25 MHz and measured sound speed changes of 16 m/s, temperature changes of 5 degrees C and had a spatial resolution of 660 microm. With future improvements utilizing the latest technologies such as two-dimensional array detectors, Micro-Electro-Mechanical Systems (MEMS), and acoustic lenses, resolutions of 1m/s, 0.5 degrees C, and 150 microm are expected. The CAHM is expected to have many useful applications, including non-invasive mass and heat transfer measurements in fluids and materials and as a medical diagnostic tool to non-intrusively visualize compositions and temperatures within the human body.

  2. Particle-Based Geometric and Mechanical Modelling of Woven Technical Textiles and Reinforcements for Composites

    NASA Astrophysics Data System (ADS)

    Samadi, Reza

    Technical textiles are increasingly being engineered and used in challenging applications, in areas such as safety, biomedical devices, architecture and others, where they must meet stringent demands including excellent and predictable load bearing capabilities. They also form the bases for one of the most widespread group of composite materials, fibre reinforced polymer-matrix composites (PMCs), which comprise materials made of stiff and strong fibres generally available in textile form and selected for their structural potential, combined with a polymer matrix that gives parts their shape. Manufacturing processes for PMCs and technical textiles, as well as parts and advanced textile structures must be engineered, ideally through simulation, and therefore diverse properties of the textiles, textile reinforcements and PMC materials must be available for predictive simulation. Knowing the detailed geometry of technical textiles is essential to predicting accurately the processing and performance properties of textiles and PMC parts. In turn, the geometry taken by a textile or a reinforcement textile is linked in an intricate manner to its constitutive behaviour. This thesis proposes, investigates and validates a general numerical tool for the integrated and comprehensive analysis of textile geometry and constitutive behaviour as required toward engineering applications featuring technical textiles and textile reinforcements. The tool shall be general with regards to the textiles modelled and the loading cases applied. Specifically, the work aims at fulfilling the following objectives: 1) developing and implementing dedicated simulation software for modelling textiles subjected to various load cases; 2) providing, through simulation, geometric descriptions for different textiles subjected to different load cases namely compaction, relaxation and shear; 3) predicting the constitutive behaviour of the textiles undergoing said load cases; 4) identifying parameters

  3. Study of the structure of 3-D composites based on carbon nanotubes in bovine serum albumin matrix by X-ray microtomography

    NASA Astrophysics Data System (ADS)

    Ignatov, D.; Zhurbina, N.; Gerasimenko, A.

    2017-01-01

    3-D composites are widely used in tissue engineering. A comprehensive analysis by X-ray microtomography was conducted to study the structure of the 3-D composites. Comprehensive analysis of the structure of the 3-D composites consisted of scanning, image reconstruction of shadow projections, two-dimensional and three-dimensional visualization of the reconstructed images and quantitative analysis of the samples. Experimental samples of composites were formed by laser vaporization of the aqueous dispersion BSA and single-walled (SWCNTs) and multi-layer (MWCNTs) carbon nanotubes. The samples have a homogeneous structure over the entire volume, the percentage of porosity of 3-D composites based on SWCNTs and MWCNTs - 16.44%, 28.31%, respectively. An average pore diameter of 3-D composites based on SWCNTs and MWCNTs - 45 μm 93 μm. 3-D composites based on carbon nanotubes in bovine serum albumin matrix can be used in tissue engineering of bone and cartilage, providing cell proliferation and blood vessel sprouting.

  4. Game Changing Technology: Woven Thermal Protection Systems

    NASA Video Gallery

    New woven composite materials are an advanced space technology that mark a major milestone toward development of the space systems that will enable extending human and robotic presence throughout t...

  5. Failure models for textile composites

    SciTech Connect

    Cox, B.

    1995-08-01

    The goals of this investigation were to: (1) identify mechanisms of failure and determine how the architecture of reinforcing fibers in 3D woven composites controlled stiffness, strength, strain to failure, work of fracture, notch sensitivity, and fatigue life; and (2) to model composite stiffness, strength, and fatigue life. A total of 11 different angle and orthogonal interlock woven composites were examined. Composite properties depended on the weave architecture, the tow size, and the spatial distributions and strength of geometrical flaws. Simple models were developed for elastic properties, strength, and fatigue life. A more complicated stochastic model, called the `Binary Model,` was developed for damage tolerance and ultimate failure. These 3D woven composites possessed an extraordinary combination of strength, damage tolerance, and notch insensitivity.

  6. Failure models for textile composites

    NASA Technical Reports Server (NTRS)

    Cox, Brian

    1995-01-01

    The goals of this investigation were to: (1) identify mechanisms of failure and determine how the architecture of reinforcing fibers in 3D woven composites controlled stiffness, strength, strain to failure, work of fracture, notch sensitivity, and fatigue life; and (2) to model composite stiffness, strength, and fatigue life. A total of 11 different angle and orthogonal interlock woven composites were examined. Composite properties depended on the weave architecture, the tow size, and the spatial distributions and strength of geometrical flaws. Simple models were developed for elastic properties, strength, and fatigue life. A more complicated stochastic model, called the 'Binary Model,' was developed for damage tolerance and ultimate failure. These 3D woven composites possessed an extraordinary combination of strength, damage tolerance, and notch insensitivity.

  7. Analysis of linear elasticity and non-linearity due to plasticity and material damage in woven and biaxial braided composites

    NASA Astrophysics Data System (ADS)

    Goyal, Deepak

    Textile composites have a wide variety of applications in the aerospace, sports, automobile, marine and medical industries. Due to the availability of a variety of textile architectures and numerous parameters associated with each, optimal design through extensive experimental testing is not practical. Predictive tools are needed to perform virtual experiments of various options. The focus of this research is to develop a better understanding of linear elastic response, plasticity and material damage induced nonlinear behavior and mechanics of load flow in textile composites. Textile composites exhibit multiple scales of complexity. The various textile behaviors are analyzed using a two-scale finite element modeling. A framework to allow use of a wide variety of damage initiation and growth models is proposed. Plasticity induced non-linear behavior of 2x2 braided composites is investigated using a modeling approach based on Hill's yield function for orthotropic materials. The mechanics of load flow in textile composites is demonstrated using special non-standard postprocessing techniques that not only highlight the important details, but also transform the extensive amount of output data into comprehensible modes of behavior. The investigations show that the damage models differ from each other in terms of amount of degradation as well as the properties to be degraded under a particular failure mode. When compared with experimental data, predictions of some models match well for glass/epoxy composite whereas other's match well for carbon/epoxy composites. However, all the models predicted very similar response when damage factors were made similar, which shows that the magnitude of damage factors are very important. Full 3D as well as equivalent tape laminate predictions lie within the range of the experimental data for a wide variety of braided composites with different material systems, which validated the plasticity analysis. Conclusions about the effect of

  8. Woven heat exchanger

    DOEpatents

    Piscitella, Roger R.

    1987-05-05

    In a woven ceramic heat exchanger using the basic tube-in-shell design, each heat exchanger consisting of tube sheets and tube, is woven separately. Individual heat exchangers are assembled in cross-flow configuration. Each heat exchanger is woven from high temperature ceramic fiber, the warp is continuous from tube to tube sheet providing a smooth transition and unitized construction.

  9. Woven heat exchanger

    DOEpatents

    Piscitella, Roger R.

    1987-01-01

    In a woven ceramic heat exchanger using the basic tube-in-shell design, each heat exchanger consisting of tube sheets and tube, is woven separately. Individual heat exchangers are assembled in cross-flow configuration. Each heat exchanger is woven from high temperature ceramic fiber, the warp is continuous from tube to tube sheet providing a smooth transition and unitized construction.

  10. Stress analysis of a rectangular implant in laminated composites using 2-D and 3-D finite elements

    NASA Technical Reports Server (NTRS)

    Chow, Wai T.; Graves, Michael J.

    1992-01-01

    An analysis method using the FEM based on the Hellinger-Reissner variation principle has been developed to determine the 3-D stresses and displacements near a rectangular implant inside a laminated composite material. Three-dimensional elements are employed in regions where the interlaminar stress is considered to be significant; 2-D elements are used in other areas. Uniaxially loaded graphite-epoxy laminates have been analyzed; the implant was modeled as four plies of 3501/6 epoxy located in the middle of the laminate. It is shown that the interlaminar stresses are an order of magnitude lower than the stress representing the applied far-field load. The stress concentration factors of both the interlaminar and in-plane stresses depend on the stacking sequence of the laminate.

  11. 3D multi-observable probabilistic inversion for the compositional and thermal structure of the lithosphere and sublithospheric upper mantle

    NASA Astrophysics Data System (ADS)

    Afonso, J. C.; Fullea, J.; Yang, Y.; Griffin, W. L.; Jones, A. G.; Connolly, J.; Lebedev, S.; O'Reilly, S. Y.

    2011-12-01

    High-resolution imaging and characterization of the thermal and compositional structure of the lithospheric and sublithospheric upper mantle are the basis for understanding the formation and evolution of the lithosphere and the interaction between the crust-mantle and lithosphere-asthenosphere systems. Unfortunately, such imaging and characterization using available geophysical-geochemical methods still present unsolved and technically challenging problems. In this contribution we present a new full-3D multi-observable inversion method particularly designed for high-resolution (regional) thermal and compositional mapping of the lithosphere and sublithospheric upper mantle. Ambient noise tomography, multiple plane wave earthquake tomography, magnetotelluric, thermal, thermodynamic, and potential field modelling are all combined in a single thermodynamic-geophysical framework and appraised within a general probabilistic (Bayesian) formulation. This circumvents the problems of strong non-linearity involved in traditional inversions, provides highly refined seismic information, minimizes the problem of trade-off between temperature and composition in wave speeds, offers critical insights into incompatibilities between traditional stand-alone methods, and takes advantage of a priori local geochemical information. Both synthetic models and preliminary results in real-case examples will be used to discuss the benefits, robustness, and limitations of this method.

  12. Modeling Three-Phase Compositional Flow on Complex 3D Unstructured Grids with Higher-Order Finite Element Methods

    NASA Astrophysics Data System (ADS)

    Moortgat, J.; Firoozabadi, A.

    2013-12-01

    Most problems of interest in hydrogeology and subsurface energy resources involve complex heterogeneous geological formations. Such domains are most naturally represented in numerical reservoir simulations by unstructured computational grids. Finite element methods are a natural choice to describe fluid flow on unstructured meshes, because the governing equations can be readily discretized for any grid-element geometry. In this work, we consider the challenging problem of fully compositional three-phase flow in 3D unstructured grids, discretized by tetrahedra, prisms, or hexahedra, and compare to simulations on 3D structured grids. We employ a combination of mixed hybrid finite element methods to solve for the pressure and flux fields in a fractional flow formulation, and higher-order discontinuous Galerkin methods for the mass transport equations. These methods are well suited to simulate flow in heterogeneous and fractured reservoirs, because they provide a globally continuous pressure and flux field, while allowing for sharp discontinuities in the phase properties, such as compositions and saturations. The increased accuracy from using higher-order methods improves the modeling of highly non-linear flow, such as gravitational and viscous fingering. We present several numerical examples to study convergence rates and the (lack of) sensitivity to gridding/mesh orientation, and mesh quality. These examples consider gravity depletion, water and gas injection in oil saturated subsurface reservoirs with species exchange between up to three fluid phases. The examples demonstrate the wide applicability of our chosen finite element methods in the study of challenging multiphase flow problems in porous, geometrically complex, subsurface media.

  13. Bioconductive 3D nano-composite constructs with tunable elasticity to initiate stem cell growth and induce bone mineralization.

    PubMed

    Sagar, Nitin; Khanna, Kunal; Sardesai, Varda S; Singh, Atul K; Temgire, Mayur; Kalita, Mridula Phukan; Kadam, Sachin S; Soni, Vivek P; Bhartiya, Deepa; Bellare, Jayesh R

    2016-12-01

    Bioactive 3D composites play an important role in advanced biomaterial design to provide molecular coupling and improve integrity with the cellular environment of the native bone. In the present study, a hybrid lyophilized polymer composite blend of anionic charged sodium salt of carboxymethyl chitin and gelatin (CMChNa-GEL) reinforced with nano-rod agglomerated hydroxyapatite (nHA) has been developed with enhanced biocompatibility and tunable elasticity. The scaffolds have an open, uniform and interconnected porous structure with an average pore diameter of 157±30μm and 89.47+0.03% with four dimensional X-ray. The aspect ratio of ellipsoidal pores decrease from 4.4 to 1.2 with increase in gelatin concentration; and from 2.14 to 1.93 with decrease in gelling temperature. The samples were resilient with elastic stain at 1.2MPa of stress also decreased from 0.33 to 0.23 with increase in gelatin concentration. The crosslinker HMDI (hexamethylene diisocyanate) yielded more resilient samples at 1.2MPa in comparison to glutaraldehyde. Increased crosslinking time from 2 to 4h in continuous compression cycle show no improvement in maximum elastic stain of 1.2MPa stress. This surface elasticity of the scaffold enables the capacity of these materials for adherent self renewal and cultivation of the NTERA-2 cL.D1 (NT2/D1), pluripotent embryonal carcinoma cell with biomechanical surface, as is shown here. Proliferation with MG-63, ALP activity and Alizarin red mineralization assay on optimized scaffold demonstrated ***p<0.001 between different time points thus showing its potential for bone healing. In pre-clinical study histological bone response of the scaffold construct displayed improved activity of bone regeneration in comparison to self healing of control groups (sham) up to week 07 after implantation in rabbit tibia critical-size defect. Therefore, this nHA-CMChNa-GEL scaffold composite exhibits inherent and efficient physicochemical, mechanical and biological

  14. Extracellular matrix composition and rigidity regulate invasive behavior and response to PDT in 3D pancreatic tumor models

    NASA Astrophysics Data System (ADS)

    Cramer, Gwendolyn; El-Hamidi, Hamid; Jafari, Seyedehrojin; Jones, Dustin P.; Celli, Jonathan P.

    2016-03-01

    The composition and mechanical compliance of the extracellular matrix (ECM) have been shown to serve as regulators of tumor growth and invasive behavior. These effects may be particularly relevant in tumors of the pancreas, noted for a profound desmoplastic reaction and an abundance of stroma rich in ECM. In view of recent progress in the clinical implementation of photodynamic therapy (PDT) for pancreatic tumors, in this report we examine how ECM composition and rheological properties impact upon invasive behavior and response to PDT in 3D multicellular pancreatic tumor spheroids in ECM environments with characterized rheological properties. Tumor spheroids were cultured initially in attachment-free conditions to form millimeter-sized spheroids that were transplanted into reconstituted ECM microenvironments (Matrigel and Type I Collagen) that were characterized using bulk oscillatory shear rheology. Analysis of growth behavior shows that the soft collagen ECM promoted growth and extensive invasion and this microenvironment was used in subsequent assessment of PDT and chemotherapy response. Evaluation of treatment response revealed that primary tumor nodule growth is inhibited more effectively with PDT, while verteporfin PDT response is significantly enhanced in the ECM-infiltrating populations that are non-responsive to oxaliplatin chemotherapy. This finding is potentially significant, suggesting the potential for PDT to target these clinically problematic invasive populations that are associated with aggressive metastatic progression and chemoresistance. Experiments to further validate and identify the mechanistic basis of this observation are ongoing.

  15. The Synergistic Effects of Matrix Stiffness and Composition on the Response of Chondroprogenitor Cells in a 3D Precondensation Microenvironment.

    PubMed

    Carrion, Bita; Souzanchi, Mohammad F; Wang, Victor T; Tiruchinapally, Gopinath; Shikanov, Ariella; Putnam, Andrew J; Coleman, Rhima M

    2016-05-01

    Improve functional quality of cartilage tissue engineered from stem cells requires a better understanding of the functional evolution of native cartilage tissue. Therefore, a biosynthetic hydrogel was developed containing RGD, hyaluronic acid and/or type-I collagen conjugated to poly(ethylene glycol) acrylate to recapitulate the precondensation microenvironment of the developing limb. Conjugation of any combination of the three ligands did not alter the shear moduli or diffusion properties of the PEG hydrogels; thus, the influence of ligand composition on chondrogenesis could be investigated in the context of varying matrix stiffness. Gene expression of ligand receptors (CD44 and the b1-integrin) as well as markers of condensation (cell clustering and N-cadherin gene expression) and chondrogenesis (Col2a1 gene expression and sGAG production) by chondroprogenitor cells in this system were modulated by both matrix stiffness and ligand composition, with the highest gene expression occurring in softer hydrogels containing all three ligands. Cell proliferation in these 3D matrices for 7 d prior to chondrogenic induction increased the rate of sGAG production in a stiffness-dependent manner. This biosynthetic hydrogel supports the features of early limb-bud condensation and chondrogenesis and is a novel platform in which the influence of the matrix physicochemical properties on these processes can be elucidated.

  16. Modeling of Nonlinear Mechanical Behavior for 3D Needled C/C-SiC Composites Under Tensile Load

    NASA Astrophysics Data System (ADS)

    Xie, Junbo; Fang, Guodong; Chen, Zhen; Liang, Jun

    2016-08-01

    This paper established a macroscopic constitutive model to describe the nonlinear stress-strain behavior of 3D needled C/C-SiC composites under tensile load. Extensive on- and off-axis tensile tests were performed to investigate the macroscopic mechanical behavior and damage characteristics of the composites. The nonlinear mechanical behavior of the material was mainly induced by matrix tensile cracking and fiber/matrix debonding. Permanent deformations and secant modulus degradation were observed in cyclic loading-unloading tests. The nonlinear stress-strain relationship of the material could be described macroscopically by plasticity deformation and stiffness degradation. In the proposed model, we employed a plasticity theory with associated plastic flow rule to describe the evolution of plastic strains. A novel damage variable was also introduced to characterize the stiffness degradation of the material. The damage evolution law was derived from the statistical distribution of material strength. Parameters of the proposed model can be determined from off-axis tensile tests. Stress-strain curves predicted by this model showed reasonable agreement with experimental results.

  17. Mixed-hybrid and vertex-discontinuous-Galerkin finite element modeling of multiphase compositional flow on 3D unstructured grids

    NASA Astrophysics Data System (ADS)

    Moortgat, Joachim; Firoozabadi, Abbas

    2016-06-01

    Problems of interest in hydrogeology and hydrocarbon resources involve complex heterogeneous geological formations. Such domains are most accurately represented in reservoir simulations by unstructured computational grids. Finite element methods accurately describe flow on unstructured meshes with complex geometries, and their flexible formulation allows implementation on different grid types. In this work, we consider for the first time the challenging problem of fully compositional three-phase flow in 3D unstructured grids, discretized by any combination of tetrahedra, prisms, and hexahedra. We employ a mass conserving mixed hybrid finite element (MHFE) method to solve for the pressure and flux fields. The transport equations are approximated with a higher-order vertex-based discontinuous Galerkin (DG) discretization. We show that this approach outperforms a face-based implementation of the same polynomial order. These methods are well suited for heterogeneous and fractured reservoirs, because they provide globally continuous pressure and flux fields, while allowing for sharp discontinuities in compositions and saturations. The higher-order accuracy improves the modeling of strongly non-linear flow, such as gravitational and viscous fingering. We review the literature on unstructured reservoir simulation models, and present many examples that consider gravity depletion, water flooding, and gas injection in oil saturated reservoirs. We study convergence rates, mesh sensitivity, and demonstrate the wide applicability of our chosen finite element methods for challenging multiphase flow problems in geometrically complex subsurface media.

  18. MnO2 nanorods/3D-rGO composite as high performance anode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Liu, Hongdong; Hu, Zhongli; Su, Yongyao; Ruan, Haibo; Hu, Rong; Zhang, Lei

    2017-01-01

    MnO2 nanorods/three-dimensional reduced graphene oxide (3D-rGO) composite has been synthesized by a simple in situ hydrothermal methord. The X-ray diffraction (XRD) pattern of the as-prepared composite reveals tetragonal structure of α-MnO2. Raman spectroscopic and X-ray photoelectron spectroscopy (XPS) of the samples confirm the coexistence of MnO2 and graphene. The Brunauer-Emmett-Teller (BET) analysis shows the large surface area of the composite. The electron microscopy images of the as-synthesized products reveals the MnO2 nanorods are homogeneously grown on 3D-rGO matrix. Electrochemical characterization exhibits the MnO2 nanorods/3D-rGO composite with large reversible capacity (595 mA h g-1 over 60 cycles at 100 mA g-1), high coulombic efficiency (above 99%), excellent rate capability and good cyclic stability. The superior electrochemical performance can be attributed to the turf-like nanostructure of composite, high capacity of MnO2 and superior electrical conductivity of 3D-rGO. It suggests that MnO2 nanorods/3D-rGO composite will be a promising anode material for Li-ion batteries.

  19. Probabilistic Modeling of High-Temperature Material Properties of a 5-Harness 0/90 Sylramic Fiber/ CVI-SiC/ MI-SiC Woven Composite

    NASA Technical Reports Server (NTRS)

    Nagpal, Vinod K.; Tong, Michael; Murthy, P. L. N.; Mital, Subodh

    1998-01-01

    An integrated probabilistic approach has been developed to assess composites for high temperature applications. This approach was used to determine thermal and mechanical properties and their probabilistic distributions of a 5-harness 0/90 Sylramic fiber/CVI-SiC/Mi-SiC woven Ceramic Matrix Composite (CMC) at high temperatures. The purpose of developing this approach was to generate quantitative probabilistic information on this CMC to help complete the evaluation for its potential application for HSCT combustor liner. This approach quantified the influences of uncertainties inherent in constituent properties called primitive variables on selected key response variables of the CMC at 2200 F. The quantitative information is presented in the form of Cumulative Density Functions (CDFs). Probability Density Functions (PDFS) and primitive variable sensitivities on response. Results indicate that the scatters in response variables were reduced by 30-50% when the uncertainties in the primitive variables, which showed the most influence, were reduced by 50%.

  20. Self-Propagating Combustion Triggered Synthesis of 3D Lamellar Graphene/BaFe12O19 Composite and Its Electromagnetic Wave Absorption Properties

    PubMed Central

    Zhao, Tingkai; Ji, Xianglin; Jin, Wenbo; Yang, Wenbo; Peng, Xiarong; Duan, Shichang; Dang, Alei; Li, Hao; Li, Tiehu

    2017-01-01

    The synthesis of 3D lamellar graphene/BaFe12O19 composites was performed by oxidizing graphite and sequentially self-propagating combustion triggered process. The 3D lamellar graphene structures were formed due to the synergistic effect of the tremendous heat induced gasification as well as huge volume expansion. The 3D lamellar graphene/BaFe12O19 composites bearing 30 wt % graphene present the reflection loss peak at −27.23 dB as well as the frequency bandwidth at 2.28 GHz (< −10 dB). The 3D lamellar graphene structures could consume the incident waves through multiple reflection and scattering within the layered structures, prolonging the propagation path of electromagnetic waves in the absorbers. PMID:28336889

  1. Multifunctional hybrid three-dimensionally woven scaffolds for cartilage tissue engineering.

    PubMed

    Moutos, Franklin T; Estes, Bradley T; Guilak, Farshid

    2010-11-10

    The successful replacement of large-scale cartilage defects or osteoarthritic lesions using tissue-engineering approaches will likely require composite biomaterial scaffolds that have biomimetic mechanical properties and can provide cell-instructive cues to control the growth and differentiation of embedded stem or progenitor cells. This study describes a novel method of constructing multifunctional scaffolds for cartilage tissue engineering that can provide both mechanical support and biological stimulation to seeded progenitor cells. 3-D woven PCL scaffolds were infiltrated with a slurry of homogenized CDM of porcine origin, seeded with human ASCs, and cultured for up to 42 d under standard growth conditions. These constructs were compared to scaffolds derived solely from CDM as well as 3-D woven PCL fabric without CDM. While all scaffolds promoted a chondrogenic phenotype of the ASCs, CDM scaffolds showed low compressive and shear moduli and contracted significantly during culture. Fiber-reinforced CDM scaffolds and 3-D woven PCL scaffolds maintained their mechanical properties throughout the culture period, while supporting the accumulation of a cartilaginous extracellular matrix. These findings show that fiber-reinforced hybrid scaffolds can be produced with biomimetic mechanical properties as well as the ability to promote ASC differentiation and chondrogenesis in vitro.

  2. In vitro study of 3D PLGA/n-HAp/β-TCP composite scaffolds with etched oxygen plasma surface modification in bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Roh, Hee-Sang; Jung, Sang-Chul; Kook, Min-Suk; Kim, Byung-Hoon

    2016-12-01

    Three-dimensional (3D) scaffolds have many advantageous properties for bone tissue engineering application, due to its controllable properties such as pore size, structural shape and interconnectivity. In this study, effects on oxygen plasma surface modification and adding of nano-hydroxyapatite (n-HAp) and β-tricalcium phosphate (β-TCP) on the 3D PLGA/n-HAp/β-TCP scaffolds for improving preosteoblast cell (MC3T3-E1) adhesion, proliferation and differentiation were investigated. The 3D PLGA/n-HAp/β-TCP scaffolds were fabricated by 3D Bio-Extruder equipment. The 3D scaffolds were prepared with 0°/90° architecture and pore size of approximately 300 μm. In addition 3D scaffolds surface were etched by oxygen plasma to enhance the hydrophilic property and surface roughness. After oxygen plasma treatment, the surface chemistry and morphology were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. And also hydrophilic property was measured by contact angle. The MC3T3-E1 cell proliferation and differentiation were investigated by MTT assay and ALP activity. In present work, the 3D PLGA/HAp/beta-TCP composite scaffold with suitable structure for the growth of osteoblast cells was successfully fabricated by 3D rapid prototyping technique. The surface hydrophilicity and roughness of 3D scaffold increased by oxygen plasma treatment had a positive effect on cell adhesion, proliferation, and differentiation. Furthermore, the differentiation of MC3T3-E1 cell was significantly enhanced by adding of n-HAp and β-TCP on 3D PLGA scaffold. As a result, combination of bioceramics and oxygen plasma treatment showed a synergistic effect on biocompatibility of 3D scaffolds. This result confirms that this technique was useful tool for improving the biocompatibility in bone tissue engineering application.

  3. Woven TPS Mechanical Property Evaluation

    NASA Technical Reports Server (NTRS)

    Gonzales, Gregory Lewis; Kao, David Jan-Woei; Stackpoole, Margaret M.

    2013-01-01

    Woven Thermal Protection Systems (WTPS) is a relatively new program funded by the Office of the Chief Technologist (OCT). The WTPS approach to producing TPS architectures uses precisely engineered 3-D weaving techniques that allow tailoring material characteristics needed to meet specific mission requirements. A series of mechanical tests were performed to evaluate performance of different weave types, and get a better understanding of failure modes expected in these three-dimensional architectures. These properties will aid in material down selection and guide selection of the appropriate WTPS for a potential mission.

  4. Influence of locational states of submicron fibers added into matrix on mechanical properties of plain-woven Carbon Fiber Composite

    NASA Astrophysics Data System (ADS)

    Kumamoto, Soichiro; Okubo, Kazuya; Fujii, Toru

    2016-01-01

    The aim of this study was to show the influence of locational states of submicron fibers added into epoxy matrix on mechanical properties of modified plane-woven carbon fiber reinforced plastic (CFRP). To change the locational states of submicron fibers, two kinds of fabrication processes were applied in preparing specimen by hand lay-up method. Submicron fibers were simply added into epoxy resin with ethanol after they were stirred by a dispersion process using homogenizer to be located far from the interface between reinforcement and matrix. In contrast, submicron fibers were attached onto the carbon fibers by injecting from a spray nozzle accompanying with ethanol to be located near the interface, after they were tentatively contained in ethanol. The plain-woven CFRP plates were fabricated by hand lay-up method and cured at 80 degree-C for 1 hour and then at 150 degree-C for 3 hours. After curing, the plain-woven CFRP plates were cut into the dimension of specimen. Tensile shear strength and Mode-II fracture toughness of CFRP were determined by tensile lap-shear test and End-notched flexure(ENF) test, respectively. When submicron fibers were located far from the interface between carbon fibers and epoxy resin, tensile shear strength and Mode-II fracture toughness of CFRP were improved 30% and 18% compared with those of unmodified case. The improvement ratio in modified case was rather low (about few percentages) in the case where submicron fibers were located near the interface. The result suggested that crack propagation should be prevented when submicron fibers were existed far from the interface due to the effective stress state around the crack tip.

  5. Survivability of Affordable Aircraft Composite Structures. Volume 1: Overview and Ballistic Impact Testing of Affordable Woven Carbon/Epoxy Composites

    DTIC Science & Technology

    2003-04-01

    Carbon/Epoxy Composites………………………...4 2.1 Introduction……………………………………………………………………………………………4 2.2 VARTM …………………………………..……………………………………………………………7 2.3 High...2.5.3.2 Stitched Laminates………………………………………………………………20 2.6 Effect of Projectile Shape on the Ballistic Perforation of VARTM Carbon/Epoxy Composite...molding processes the cost of production has been drastically reduced. Resin transfer molding ( RTM ) and vacuum assisted resin infusion molding

  6. 3D Progressive Damage Modeling for Laminated Composite Based on Crack Band Theory and Continuum Damage Mechanics

    NASA Technical Reports Server (NTRS)

    Wang, John T.; Pineda, Evan J.; Ranatunga, Vipul; Smeltzer, Stanley S.

    2015-01-01

    A simple continuum damage mechanics (CDM) based 3D progressive damage analysis (PDA) tool for laminated composites was developed and implemented as a user defined material subroutine to link with a commercially available explicit finite element code. This PDA tool uses linear lamina properties from standard tests, predicts damage initiation with an easy-to-implement Hashin-Rotem failure criteria, and in the damage evolution phase, evaluates the degradation of material properties based on the crack band theory and traction-separation cohesive laws. It follows Matzenmiller et al.'s formulation to incorporate the degrading material properties into the damaged stiffness matrix. Since nonlinear shear and matrix stress-strain relations are not implemented, correction factors are used for slowing the reduction of the damaged shear stiffness terms to reflect the effect of these nonlinearities on the laminate strength predictions. This CDM based PDA tool is implemented as a user defined material (VUMAT) to link with the Abaqus/Explicit code. Strength predictions obtained, using this VUMAT, are correlated with test data for a set of notched specimens under tension and compression loads.

  7. 3D Non-destructive Imaging of Punctures in Polyethylene Composite Armor by THz Time Domain Spectroscopy

    NASA Astrophysics Data System (ADS)

    Palka, N.; Panowicz, R.; Ospald, F.; Beigang, R.

    2015-08-01

    An ultra-high molecular weight polyethylene composite sample totally punctured by a projectile was examined by THz TDS raster scanning method in reflection configuration. The scanning results correctly match the distribution of delaminations inside the sample, which was proven with cross-sectional and frontal views after waterjet cutting. For further analysis, a signal-processing algorithm based on the deconvolution method was developed and the modified reference signal was used to reduce disturbances. The complex refractive index of the sample was determined by transmission TDS technique and was later used for the simulation of pulse propagation by the finite difference time domain method. These simulations verified the correctness of the proposed method and showed its constraints. Using the proposed algorithm, the ambiguous raw THz image was converted into a binary 3D image of the sample, which consists only of two areas: sample—polyethylene and delamination—air. As a result, a clear image of the distribution of delaminations with their spatial extent was obtained which can be used for further comparative analysis. The limitation of the proposed method is that parts of the central area of the puncture cannot be analyzed because tilted layers deflect the incident signal.

  8. Bile canaliculi formation and biliary transport in 3D sandwich-cultured hepatocytes in dependence of the extracellular matrix composition.

    PubMed

    Deharde, Daniela; Schneider, Christin; Hiller, Thomas; Fischer, Nicolas; Kegel, Victoria; Lübberstedt, Marc; Freyer, Nora; Hengstler, Jan G; Andersson, Tommy B; Seehofer, Daniel; Pratschke, Johann; Zeilinger, Katrin; Damm, Georg

    2016-10-01

    Primary human hepatocytes (PHH) are still considered as gold standard for investigation of in vitro metabolism and hepatotoxicity in pharmaceutical research. It has been shown that the three-dimensional (3D) cultivation of PHH in a sandwich configuration between two layers of extracellular matrix (ECM) enables the hepatocytes to adhere three dimensionally leading to formation of in vivo like cell-cell contacts and cell-matrix interactions. The aim of the present study was to investigate the influence of different ECM compositions on morphology, cellular arrangement and bile canaliculi formation as well as bile excretion processes in PHH sandwich cultures systematically. Freshly isolated PHH were cultured for 6 days between two ECM layers made of collagen and/or Matrigel in four different combinations. The cultures were investigated by phase contrast microscopy and immunofluorescence analysis with respect to cell-cell connections, repolarization as well as bile canaliculi formation. The influence of the ECM composition on cell activity and viability was measured using the XTT assay and a fluorescent dead or alive assay. Finally, the bile canalicular transport was analyzed by live cell imaging to monitor the secretion and accumulation of the fluorescent substance CDF in bile canaliculi. Using collagen and Matrigel in different compositions in sandwich cultures of hepatocytes, we observed differences in morphology, cellular arrangement and cell activity of PHH in dependence of the ECM composition. Sandwich-cultured hepatocytes with an underlay of collagen seem to represent the best in vivo tissue architecture in terms of formation of trabecular cell arrangement. Cultures overlaid with collagen were characterized by the formation of abundant bile canaliculi, while the bile canaliculi network in hepatocytes cultured on a layer of Matrigel and overlaid with collagen showed the most branched and stable canalicular network. All cultures showed a time-dependent leakage of

  9. Microwave-synthesized freestanding iron-carbon nanotubes on polyester composites of woven Kevlar fibre and silver nanoparticle-decorated graphene

    PubMed Central

    Hazarika, Ankita; Deka, Biplab K.; Kim, DoYoung; Kong, Kyungil; Park, Young-Bin; Park, Hyung Wook

    2017-01-01

    We synthesized Ag nanoparticle-decorated multilayered graphene nanosheets (Ag-graphene) from graphite nanoplatelets and silver nitrate through 90–100 s of microwave exposure, without the use of any mineral acids or harsh reducing agents. Fe nanoparticle-decorated carbon nanotubes (Fe-CNTs) were grown on polypyrrole (PPy) deposited on woven Kevlar fibre (WKF), using ferrocene as a catalyst, under microwave irradiation. Fe-CNTs grown on WKF and Ag-graphene dispersed in polyester resin (PES) were combined to fabricate Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites by vacuum-assisted resin transfer moulding. The combined effect of Fe-CNTs and Ag-graphene in the resulting composites resulted in a remarkable enhancement of tensile properties (a 192.56% increase in strength and 100.64% increase in modulus) as well as impact resistance (a 116.33% increase). The electrical conductivity significantly increased for Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites. The effectiveness of electromagnetic interference shielding, which relies strongly on the Ag-graphene content in the composites, was 25 times higher in Ag-graphene/Fe-CNT/PPy-coated WKF/PES than in neat WKF/PES composites. The current work offers a novel route for fabricating highly promising, cost effective WKF/PES composites through microwave-assisted synthesis of Fe-CNTs and Ag-graphene. PMID:28074877

  10. Microwave-synthesized freestanding iron-carbon nanotubes on polyester composites of woven Kevlar fibre and silver nanoparticle-decorated graphene

    NASA Astrophysics Data System (ADS)

    Hazarika, Ankita; Deka, Biplab K.; Kim, Doyoung; Kong, Kyungil; Park, Young-Bin; Park, Hyung Wook

    2017-01-01

    We synthesized Ag nanoparticle-decorated multilayered graphene nanosheets (Ag-graphene) from graphite nanoplatelets and silver nitrate through 90–100 s of microwave exposure, without the use of any mineral acids or harsh reducing agents. Fe nanoparticle-decorated carbon nanotubes (Fe-CNTs) were grown on polypyrrole (PPy) deposited on woven Kevlar fibre (WKF), using ferrocene as a catalyst, under microwave irradiation. Fe-CNTs grown on WKF and Ag-graphene dispersed in polyester resin (PES) were combined to fabricate Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites by vacuum-assisted resin transfer moulding. The combined effect of Fe-CNTs and Ag-graphene in the resulting composites resulted in a remarkable enhancement of tensile properties (a 192.56% increase in strength and 100.64% increase in modulus) as well as impact resistance (a 116.33% increase). The electrical conductivity significantly increased for Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites. The effectiveness of electromagnetic interference shielding, which relies strongly on the Ag-graphene content in the composites, was 25 times higher in Ag-graphene/Fe-CNT/PPy-coated WKF/PES than in neat WKF/PES composites. The current work offers a novel route for fabricating highly promising, cost effective WKF/PES composites through microwave-assisted synthesis of Fe-CNTs and Ag-graphene.

  11. Microwave-synthesized freestanding iron-carbon nanotubes on polyester composites of woven Kevlar fibre and silver nanoparticle-decorated graphene.

    PubMed

    Hazarika, Ankita; Deka, Biplab K; Kim, DoYoung; Kong, Kyungil; Park, Young-Bin; Park, Hyung Wook

    2017-01-11

    We synthesized Ag nanoparticle-decorated multilayered graphene nanosheets (Ag-graphene) from graphite nanoplatelets and silver nitrate through 90-100 s of microwave exposure, without the use of any mineral acids or harsh reducing agents. Fe nanoparticle-decorated carbon nanotubes (Fe-CNTs) were grown on polypyrrole (PPy) deposited on woven Kevlar fibre (WKF), using ferrocene as a catalyst, under microwave irradiation. Fe-CNTs grown on WKF and Ag-graphene dispersed in polyester resin (PES) were combined to fabricate Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites by vacuum-assisted resin transfer moulding. The combined effect of Fe-CNTs and Ag-graphene in the resulting composites resulted in a remarkable enhancement of tensile properties (a 192.56% increase in strength and 100.64% increase in modulus) as well as impact resistance (a 116.33% increase). The electrical conductivity significantly increased for Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites. The effectiveness of electromagnetic interference shielding, which relies strongly on the Ag-graphene content in the composites, was 25 times higher in Ag-graphene/Fe-CNT/PPy-coated WKF/PES than in neat WKF/PES composites. The current work offers a novel route for fabricating highly promising, cost effective WKF/PES composites through microwave-assisted synthesis of Fe-CNTs and Ag-graphene.

  12. Woven heat exchanger

    DOEpatents

    Piscitella, R.R.

    1984-07-16

    This invention relates to a heat exchanger for waste heat recovery from high temperature industrial exhaust streams. In a woven ceramic heat exchanger using the basic tube-in-shell design, each heat exchanger consisting of tube sheets and tube, is woven separately. Individual heat exchangers are assembled in cross-flow configuration. Each heat exchanger is woven from high temperature ceramic fiber, the warp is continuous from tube to tube sheet providing a smooth transition and unitized construction.

  13. Feasibility Study for Ballet E-Learning: Automatic Composition System for Ballet "Enchainement" with Online 3D Motion Data Archive

    ERIC Educational Resources Information Center

    Umino, Bin; Longstaff, Jeffrey Scott; Soga, Asako

    2009-01-01

    This paper reports on "Web3D dance composer" for ballet e-learning. Elementary "petit allegro" ballet steps were enumerated in collaboration with ballet teachers, digitally acquired through 3D motion capture systems, and categorised into families and sub-families. Digital data was manipulated into virtual reality modelling language (VRML) and fit…

  14. Synthesis and Application of Novel 3D Magnetic Chlorogenic Acid Imprinted Polymers Based on a Graphene-Carbon Nanotube Composite.

    PubMed

    Yan, Liang; Yin, Yuli; Lv, Piaopiao; Zhang, Zhaohui; Wang, Jing; Long, Fang

    2016-04-20

    A novel three-dimensional (3D) magnetic chlorogenic acid (CGA) imprinted polymer (MMIP) was prepared with novel carbon hybrid nanocomposite as the carrier, chlorogenic acid as the template molecule, and methacrylic acid as the functional monomer. The 3D MMIPs were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, vibrating sample magnetometer, and UV spectrometry in detail. The results showed that the imprinted layer was attached successfully on the surface of a 3D magnetic carbon hybrid nanocomposite. The adsorption performance of the 3D MMIPs was investigated, and the results showed that the 3D MMIPs exhibited high adsorption capacity and fast adsorption rate toward CGA with a maximum adsorption capacity of 10.88 mg g(-1). The extraction conditions involving washing solvent, the pH of eluent solvent, elution volume, and desorption time were also investigated in detail. Combined with high-performance liquid chromatography, the 3D MMIPs have been applied to successfully extract CGA from Eucommia leaf extract samples.

  15. 77 FR 47363 - Narrow Woven Ribbons With Woven Selvedge From the People's Republic of China: Preliminary Results...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-08

    ... manufacture of typewriter or printer ribbons; (5) Narrow woven labels and apparel tapes, cut-to-length or cut... separate entities. \\28\\ See Sigma Corp. v. United States, 117 F.3d 1401, 1405-06 (Fed. Cir. 1997... 27296, 27340 (May 19, 1997); see also Nippon Steel Corp. v. United States, 337 F.3d 1373, 1382-83...

  16. Composite System of Graphene Oxide and Polypeptide Thermogel As an Injectable 3D Scaffold for Adipogenic Differentiation of Tonsil-Derived Mesenchymal Stem Cells.

    PubMed

    Patel, Madhumita; Moon, Hyo Jung; Ko, Du Young; Jeong, Byeongmoon

    2016-03-02

    As two-dimensional (2D) nanomaterials, graphene (G) and graphene oxide (GO) have evolved into new platforms for biomedical research as biosensors, imaging agents, and drug delivery carriers. In particular, the unique surface properties of GO can be an important tool in modulating cellular behavior and various biological sequences. Here, we report that a composite system of graphene oxide/polypeptide thermogel (GO/P), prepared by temperature-sensitive sol-to-gel transition of a GO-suspended poly(ethylene glycol)-poly(L-alanine) (PEG-PA) aqueous solution significantly enhances the expression of adipogenic biomarkers, including PPAR-γ, CEBP-α, LPL, AP2, ELOVL3, and HSL, compared to both a pure hydrogel system and a composite system of G/P, graphene-incorporated hydrogel. We prove that insulin, an adipogenic differentiation factor, preferentially adhered to GO, is supplied to the incorporated stem cells in a sustained manner over the three-dimensional (3D) cell culture period. On the other hand, insulin is partially denatured in the presence of G and interferes with the adipogenic differentiation of the stem cells. The study suggests that a 2D/3D composite system is a promising platform as a 3D cell culture matrix, where the surface properties of 2D materials in modulating the fates of the stem cells are effectively transcribed in a 3D culture system.

  17. Bias extension test on an unbalanced woven composite reinforcement: Experiments and modeling via a second-gradient continuum approach

    NASA Astrophysics Data System (ADS)

    Barbagallo, Gabriele; Madeo, Angela; Azehaf, Ismael; Giorgio, Ivan; Morestin, Fabrice; Boisse, Philippe

    2017-01-01

    The classical continuum models used for the woven fabrics do not fully describe the whole set of phenomena that occur during the testing of those materials. This incompleteness is partially due to the absence of energy terms related to some micro-structural properties of the fabric and, in particular, to the bending stiffness of the yarns. To account for the most fundamental microstructure-related deformation mechanisms occurring in unbalanced interlocks, a second-gradient, hyperelastic, initially orthotropic continuum model is proposed. A constitutive expression for the strain energy density is introduced to account for i) in-plane shear deformations, ii) highly different bending stiffnesses in the warp and weft directions and iii) fictive elongations in the warp and weft directions which eventually describe the relative sliding of the yarns. Numerical simulations which are able to reproduce the experimental behavior of unbalanced carbon interlocks subjected to a Bias Extension Test are presented. In particular, the proposed model captures the macroscopic asymmetric S-shaped deformation of the specimen, as well as the main features of the associated deformation patterns of the yarns at the mesoscopic scale.

  18. Synergistic Effects of Temperature, Oxidation and Multicracking Modes on Damage Evolution and Life Prediction of 2D Woven Ceramic-Matrix Composites under Tension-Tension Fatigue Loading

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-11-01

    In this paper, the synergistic effects of temperature, oxidation and multicracking modes on damage evolution and life prediction in 2D woven ceramic-matrix composites (CMCs) have been investigated. The damage parameter of fatigue hysteresis dissipated energy and the interface shear stress were used to monitor the damage evolution inside of CMCs. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface/fiber oxidation model, interface wear model and fibers statistical failure model at elevated temperature, based on the assumption that the fiber strength is subjected to two-parameter Weibull distribution and the load carried by broken and intact fibers satisfy the Global Load Sharing (GLS) criterion. When the broken fibers fraction approaches to the critical value, the composite fatigue fractures. The evolution of fatigue hysteresis dissipated energy, the interface shear stress and broken fibers fraction versus cycle number, and the fatigue life S-N curves of SiC/SiC at 1000, 1200 and 1300 °C in air and steam condition have been predicted. The synergistic effects of temperature, oxidation, fatigue peak stress, and multicracking modes on the evolution of interface shear stress and fatigue hysteresis dissipated energy versus cycle numbers curves have been analyzed.

  19. SU-C-213-05: Evaluation of a Composite Copper-Plastic Material for a 3D Printed Radiation Therapy Bolus

    SciTech Connect

    Vitzthum, L; Ehler, E; Sterling, D; Reynolds, T; Higgins, P; Dusenbery, K

    2015-06-15

    Purpose: To evaluate a novel 3D printed bolus fabricated from a copper-plastic composite as a thin flexible, custom fitting device that can replicate doses achieved with conventional bolus techniques. Methods: Two models of bolus were created on a 3D printer using a composite copper-PLA/PHA. Firstly, boluses were constructed at thicknesses of 0.4, 0.6 and 0.8 mm. Relative dose measurements were performed under the bolus with an Attix Chamber as well as with radiochromic film. Results were compared to superficial Attix Chamber measurements in a water equivalent material to determine the dosimetric water equivalence of the copper-PLA/PHA plastic. Secondly, CT images of a RANDO phantom were used to create a custom fitting bolus across the anterolateral scalp. Surface dose with the bolus placed on the RANDO phantom was measured with radiochromic film at tangential angles with 6, 10, 10 flattening filter free (FFF) and 18 MV photon beams. Results: Mean surface doses for 6, 10, 10FFF and 18 MV were measured as a percent of Dmax for the flat bolus devices of each thickness. The 0.4 mm thickness bolus was determined to be near equivalent to 2.5 mm depth in water for all four energies. Surface doses ranged from 59–63% without bolus and 85–90% with the custom 0.4 mm copper-plastic bolus relative to the prescribed dose for an oblique tangential beam arrangement on the RANDO phantom. Conclusion: Sub-millimeter thickness, 3D printed composite copper-PLA/PHA bolus can provide a build-up effect equivalent to conventional bolus. At this thickness, the 3D printed bolus allows a level of flexure that may provide more patient comfort than current 3D printing materials used in bolus fabrication while still retaining the CT based custom patient shape. Funding provided by an intra-department grant of the University of Minnesota Department of Radiation Oncology.

  20. Effect of GIA models with 3D composite mantle viscosity on GRACE mass balance estimates for Antarctica

    NASA Astrophysics Data System (ADS)

    van der Wal, Wouter; Whitehouse, Pippa L.; Schrama, Ernst J. O.

    2015-03-01

    Seismic data indicate that there are large viscosity variations in the mantle beneath Antarctica. Consideration of such variations would affect predictions of models of Glacial Isostatic Adjustment (GIA), which are used to correct satellite measurements of ice mass change. However, most GIA models used for that purpose have assumed the mantle to be uniformly stratified in terms of viscosity. The goal of this study is to estimate the effect of lateral variations in viscosity on Antarctic mass balance estimates derived from the Gravity Recovery and Climate Experiment (GRACE) data. To this end, recently-developed global GIA models based on lateral variations in mantle temperature are tuned to fit constraints in the northern hemisphere and then compared to GPS-derived uplift rates in Antarctica. We find that these models can provide a better fit to GPS uplift rates in Antarctica than existing GIA models with a radially-varying (1D) rheology. When 3D viscosity models in combination with specific ice loading histories are used to correct GRACE measurements, mass loss in Antarctica is smaller than previously found for the same ice loading histories and their preferred 1D viscosity profiles. The variation in mass balance estimates arising from using different plausible realizations of 3D viscosity amounts to 20 Gt/yr for the ICE-5G ice model and 16 Gt/yr for the W12a ice model; these values are larger than the GRACE measurement error, but smaller than the variation arising from unknown ice history. While there exist 1D Earth models that can reproduce the total mass balance estimates derived using 3D Earth models, the spatial pattern of gravity rates can be significantly affected by 3D viscosity in a way that cannot be reproduced by GIA models with 1D viscosity. As an example, models with 1D viscosity always predict maximum gravity rates in the Ross Sea for the ICE-5G ice model, however, for one of the three preferred 3D models the maximum (for the same ice model) is found

  1. Analysis of Composite Skin-Stiffener Debond Specimens Using a Shell/3D Modeling Technique and Submodeling

    NASA Technical Reports Server (NTRS)

    OBrien, T. Kevin (Technical Monitor); Krueger, Ronald; Minguet, Pierre J.

    2004-01-01

    The application of a shell/3D modeling technique for the simulation of skin/stringer debond in a specimen subjected to tension and three-point bending was studied. The global structure was modeled with shell elements. A local three-dimensional model, extending to about three specimen thicknesses on either side of the delamination front was used to model the details of the damaged section. Computed total strain energy release rates and mixed-mode ratios obtained from shell/3D simulations were in good agreement with results obtained from full solid models. The good correlation of the results demonstrated the effectiveness of the shell/3D modeling technique for the investigation of skin/stiffener separation due to delamination in the adherents. In addition, the application of the submodeling technique for the simulation of skin/stringer debond was also studied. Global models made of shell elements and solid elements were studied. Solid elements were used for local submodels, which extended between three and six specimen thicknesses on either side of the delamination front to model the details of the damaged section. Computed total strain energy release rates and mixed-mode ratios obtained from the simulations using the submodeling technique were not in agreement with results obtained from full solid models.

  2. Mechanical, Electromagnetic, and X-ray Shielding Characterization of a 3D Printable Tungsten-Polycarbonate Polymer Matrix Composite for Space-Based Applications

    NASA Astrophysics Data System (ADS)

    Shemelya, Corey M.; Rivera, Armando; Perez, Angel Torrado; Rocha, Carmen; Liang, Min; Yu, Xiaoju; Kief, Craig; Alexander, David; Stegeman, James; Xin, Hao; Wicker, Ryan B.; MacDonald, Eric; Roberson, David A.

    2015-08-01

    Material-extrusion three-dimensional (3D) printing has recently attracted much interest because of its process flexibility, rapid response to design alterations, and ability to create structures "on-the-go". For this reason, 3D printing has possible applications in rapid creation of space-based devices, for example cube satellites (CubeSat). This work focused on fabrication and characterization of tungsten-doped polycarbonate polymer matrix composites specifically designed for x-ray radiation-shielding applications. The polycarbonate-tungsten polymer composite obtained intentionally utilizes low loading levels to provide x-ray shielding while limiting effects on other properties of the material, for example weight, electromagnetic functionality, and mechanical strength. The fabrication process, from tungsten functionalization to filament extrusion and material characterization, is described, including printability, determination of x-ray attenuation, tensile strength, impact resistance, and gigahertz permittivity, and failure analysis. The proposed materials are uniquely advantageous when implemented in 3D printed structures, because even a small volume fraction of tungsten has been shown to substantially alter the properties of the resulting composite.

  3. Acoustic Emission and Damage Accumulation for Various Woven C/SiC Composites Tested in Tension at Room Temperature

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory; Petko, Jeanne; Kiser, James D.

    2002-01-01

    Modal acoustic emission (AE) has proven to be an excellent technique to monitor damage accumulation in ceramic matrix composites. In this study, AE was used to monitor tensile load-unload-reload hysteresis tests for a variety of C fiber reinforced, Sic matrix composites. C/SiC composites were reinforced with T-300 and IM7 fibers, had C, multilayer, or pseudo-porous C interphases, and had chemical vapor infiltrated Sic or melt-infiltrated SiC matrices. All of the composites exhibited considerable AE during testing. The extent and nature of the AE activity will be analyzed and discussed in light of matrix cracking and the variety of composite constituents. It is hoped that understanding the nature of stress-dependent damage accumulation in these materials can be of use in life-modeling for these types of composites.

  4. Acoustic Emission and Damage Accumulation for Various Woven C/SiC Composites Tested in Tension at Room Temperature

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Petko, Jeanne; Kiser, James D.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Modal acoustic emission (AE) has proven to be an excellent technique to monitor damage accumulation in ceramic matrix composites. In this study, AE was used to monitor tensile load-unload-reload hysteresis tests for a variety of C fiber reinforced, SiC matrix composites. C/SiC composites were reinforced with T300 and IM7 fibers, had C, multilayer, or pseudo-porous C interphases, and had chemical vapor infiltrated SiC or melt-infiltrated SiC matrices. All of the composites exhibited considerable AE during testing. The extent and nature of the AE activity will be analyzed and discussed in light of matrix cracking and the variety of composite constituents. It is hoped that understanding the nature of stress dependent damage accumulation in these materials can be of use in life modeling for these types of composites.

  5. Analysis of Composite Skin-Stiffener Debond Specimens Using Volume Elements and a Shell/3D Modeling Technique

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; Minguet, Pierre J.; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    The debonding of a skin/stringer specimen subjected to tension was studied using three-dimensional volume element modeling and computational fracture mechanics. Mixed mode strain energy release rates were calculated from finite element results using the virtual crack closure technique. The simulations revealed an increase in total energy release rate in the immediate vicinity of the free edges of the specimen. Correlation of the computed mixed-mode strain energy release rates along the delamination front contour with a two-dimensional mixed-mode interlaminar fracture criterion suggested that in spite of peak total energy release rates at the free edge the delamination would not advance at the edges first. The qualitative prediction of the shape of the delamination front was confirmed by X-ray photographs of a specimen taken during testing. The good correlation between prediction based on analysis and experiment demonstrated the efficiency of a mixed-mode failure analysis for the investigation of skin/stiffener separation due to delamination in the adherents. The application of a shell/3D modeling technique for the simulation of skin/stringer debond in a specimen subjected to three-point bending is also demonstrated. The global structure was modeled with shell elements. A local three-dimensional model, extending to about three specimen thicknesses on either side of the delamination front was used to capture the details of the damaged section. Computed total strain energy release rates and mixed-mode ratios obtained from shell/3D simulations were in good agreement with results obtained from full solid models. The good correlations of the results demonstrated the effectiveness of the shell/3D modeling technique for the investigation of skin/stiffener separation due to delamination in the adherents.

  6. Li2S@C composite incorporated into 3D reduced graphene oxide as a cathode material for lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Wang, D. H.; Xie, D.; Yang, T.; Zhong, Y.; Wang, X. L.; Xia, X. H.; Gu, C. D.; Tu, J. P.

    2016-05-01

    Surface conductive engineering on Li2S is critical for construction of advanced cathodes of lithium-sulfur batteries. Herein, we construct a high-performance Li2S-based composite cathode with the help of three-dimensional reduced graphene oxide (3D-rGO) network and outer carbon coating. Typically, the Li2S@C particles are uniformly embedded into 3D-rGO to form a binder-free 3D-rGO-Li2S@C cathode by the combination of a liquid solution-evaporation coating and PVP (Polyvinyl Pyrrolidone) carbonization. The 3D-rGO-Li2S@C cathode exhibits a high initial discharge capacity of 856 mAh g-1 at 0.1C, superior cycling stability with a capacity of 388.4 mAh g-1 after 200 cycles at 1C, corresponding to a low capacity fading rate. It is demonstrated that the outer conductive coating is effective and necessary for electrochemical enhancement of Li2S cathodes by improving electrical conductivity and prohibiting polysulfide from shuttling during cycling.

  7. 3D architecture of a graphene/CoMoO4 composite for asymmetric supercapacitors usable at various temperatures.

    PubMed

    Jiang, Yaru; Zheng, Xin; Yan, Xiaoqin; Li, Yong; Zhao, Xuan; Zhang, Yue

    2017-05-01

    Designing and optimizing the electrode materials and studying the electrochemical performance or cycle life of the supercapacitor under different working conditions are crucial to its practical application. Herein, we proposed a rational design of 3D-graphene/CoMoO4 nanoplates by a facile two-step hydrothermal method. Owing to the high electron transfer rate of graphene and the high activity of the CoMoO4 nanoplates, the three-dimensional electrode architectures achieved remarkable electrochemical performances with high areal specific capacitance (1255.24F/g at 1A/g) and superior cycling stability (91.3% of the original specific capacitance after 3000 cycles at 1A/g). The all-solid-state asymmetric supercapacitor composed of 3D-graphene/CoMoO4 and activated carbon (AC) exhibited a specific capacitance of 109F/g at 0.2A/g and an excellent cycling stability with only 12.1% of the initial specific capacitance off after 3000 cycles at 2A/g. The effects of temperature and charge-discharge current densities on the charge storage capacity of the supercapacitor were also investigated in detail for practical applications.

  8. Hydrothermal synthesis of 3D urchin-like Ag/TiO2/reduced graphene oxide composites and its enhanced photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Liu, Yuhuan; Zhou, Yi; Yang, Luyue; Wang, Yutang; Wu, Yiwei; Li, Chaocheng; Lu, Jun

    2016-09-01

    Innovative 3D urchin-like ternary TiO2 composites, which combine Ag nanoparticles with graphene, have been successfully synthesized through a simple hydrothermal method. This process employed nontoxic and mild dihydrate sodium citrate as a reducing agent. During the hydrothermal process, graphene oxide and AgNO3 were reduced to reduced graphene oxide (RGO) and Ag, respectively. Subsequently, they were grown on the surface of rutile TiO2 with a 3D urchin-like microsphere (1.5 μm). The as-prepared 3D urchin-like composites were characterized by X-ray diffraction, SEM and TEM. These techniques were also employed to ensure the morphology of urchin-like and rutile phase of TiO2. FT-IR, Raman spectroscopy and XPS characterization demonstrated the successful reduction in AgNO3 and graphite oxide to metallic Ag and RGO. The UV-visible spectrum of the ternary composite displayed strong absorption in the visible light region, which was attributed to the efficient electron transport of well-dispersed Ag nanoparticles (20-40 nm) and the formation of Ti-O-C bond between graphene and titania. The synthesized urchin-like ternary composite exhibited enhanced photocatalytic activity (98.7 %) for Rhodamine B degradation. This work provides a very convenient chemical route to the scalable production of Ag/TiO2/RGO ternary composite photocatalyst for potential applications in solving the environmental problems and energy issues. Also, the proposed mechanism underlying the photocatalytic degradation of Rhodamine B dyes was discussed.

  9. The Effects of 3D-Representation Instruction on Composite-Solid Surface-Area Learning for Elementary School Students

    ERIC Educational Resources Information Center

    Sung, Yao-Ting; Shih, Pao-Chen; Chang, Kuo-En

    2015-01-01

    Providing instruction on spatial geometry, specifically how to calculate the surface areas of composite solids, challenges many elementary school teachers. Determining the surface areas of composite solids involves complex calculations and advanced spatial concepts. The goals of this study were to build on students' learning processes for…

  10. Tension-Compression Fatigue Behavior of 2D and 3D Polymer Matrix Composites at Elevated Temperature

    DTIC Science & Technology

    2015-09-21

    performance in elevated temperature environments. High- temperature polymer matrix composites (HTPMCs) are being considered for such applications . However...the polymer matrix in most HTPMCs cannot operate at temperatures required for many aerospace structural applications . Continuous research seeks to...temperature polymer matrix composites (HTPMCs) applications , other polyimide resins replacement are being researched and developed due to the carcinogenic

  11. Influence of resin system on the energy absorption capability and morphological properties of plain woven kenaf composites

    NASA Astrophysics Data System (ADS)

    Salman, S. D.; Leman, Z.; Sultan, M. T. H.; Ishak, M. R.; Cardona, F.

    2015-12-01

    Due to both environmental and technical advantages, natural fibers are being used as reinforcement of polymeric composite in many industries. The flexibility of the most natural fibers is one of the important technical characteristic which allows them to resist impact forces. An investigation was carried out to compare the energy absorption capability of kenaf/PVB film and kenaf/epoxy composites. The hot and cold press techniques were used to fabricate the specimens with 35% kenaf fibre weight fraction. The charpy impact test was performed on forty notched specimens using a pendulum impact tester with different hammer energy. The results showed that the kenaf/PVB film composite has the highest energy absorption, strength and toughness compared with the epoxy composite. At high energy levels, the impact strength and toughness of the kenaf/PVB film was six times of kenaf/epoxy composite. In addition, the scanning electron microscopy was assessed to demonstrate the different failure in fracture surfaces. It was found that the kenaf/PVB film composite failed by fibre fracture while kenaf/epoxy composite failed by a combination of fibre pull-out and fibre fracture as well as crack propagations through the matrix.

  12. Temperature Dependence of Electrical Resistance of Woven Melt-Infiltrated SiCf/SiC Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Appleby, Matthew P.; Morscher, Gregory N.; Zhu, Dongming

    2016-01-01

    Recent studies have successfully shown the use of electrical resistance (ER)measurements to monitor room temperature damage accumulation in SiC fiber reinforced SiC matrix composites (SiCf/SiC) Ceramic Matrix Composites (CMCs). In order to determine the feasibility of resistance monitoring at elevated temperatures, the present work investigates the temperature dependent electrical response of various MI (Melt Infiltrated)-CVI (Chemical Vapor Infiltrated) SiC/SiC composites containing Hi-Nicalon Type S, Tyranno ZMI and SA reinforcing fibers. Test were conducted using a commercially available isothermal testing apparatus as well as a novel, laser-based heating approach developed to more accurately simulate thermomechanical testing of CMCs. Secondly, a post-test inspection technique is demonstrated to show the effect of high-temperature exposure on electrical properties. Analysis was performed to determine the respective contribution of the fiber and matrix to the overall composite conductivity at elevated temperatures. It was concluded that because the silicon-rich matrix material dominates the electrical response at high temperature, ER monitoring would continue to be a feasible method for monitoring stress dependent matrix cracking of melt-infiltrated SiC/SiC composites under high temperature mechanical testing conditions. Finally, the effect of thermal gradients generated during localized heating of tensile coupons on overall electrical response of the composite is determined.

  13. Distinct failure modes in bio-inspired 3D-printed staggered composites under non-aligned loadings

    NASA Astrophysics Data System (ADS)

    Slesarenko, Viacheslav; Kazarinov, Nikita; Rudykh, Stephan

    2017-03-01

    The superior mechanical properties of biological materials originate in their complex hierarchical microstructures, combining stiff and soft constituents at different length scales. In this work, we employ a three-dimensional multi-materials printing to fabricate the bio-inspired staggered composites, and study their mechanical properties and failure mechanisms. We observe that bio-inspired staggered composites with inclined stiff tablets are able to undergo two different failure modes, depending on the inclination angle. We find that such artificial structure demonstrates high toughness only under loading applied at relatively small angle to the tablets stacking direction, while for higher angles the composites fail catastrophically. This aspect of the failure behavior was captured experimentally as well as by means of the finite element analysis. We show that even a relatively simple failure model with a strain energy limiter, can be utilized to qualitatively distinguish these two different modes of failure, occurring in the artificial bio-inspired composites.

  14. Laser-Deposited In Situ TiC-Reinforced Nickel Matrix Composites: 3D Microstructure and Tribological Properties (Postprint)

    DTIC Science & Technology

    2014-04-03

    laser-engineered net shaping TM process. These composites consist of an in situ formed and homogeneously distributed titanium carbide (TiC) phase...distributed primary and eutectic titanium carbide precipitates as well as a graphitic phase encompassing the primary carbides within the nickel...distributed titanium carbide (TiC) phase reinforcing the nickel matrix. Additionally, by tailoring the Ti/C ratio in these composites, an additional

  15. Mechanical and in vitro performance of apatite-wollastonite glass ceramic reinforced hydroxyapatite composite fabricated by 3D-printing.

    PubMed

    Suwanprateeb, J; Sanngam, R; Suvannapruk, W; Panyathanmaporn, T

    2009-06-01

    In situ hydroxyapatite/apatite-wollastonite glass ceramic composite was fabricated by a three dimensional printing (3DP) technique and characterized. It was found that the as-fabricated mean green strength of the composite was 1.27 MPa which was sufficient for general handling. After varying sintering temperatures (1050-1300 degrees C) and times (1-10 h), it was found that sintering at 1300 degrees C for 3 h gave the greatest flexural modulus and strength, 34.10 GPa and 76.82 MPa respectively. This was associated with a decrease in porosity and increase in densification ability of the composite resulting from liquid phase sintering. Bioactivity tested by soaking in simulated body fluid (SBF) and In Vitro toxicity studies showed that 3DP hydroxyapatite/A-W glass ceramic composite was non-toxic and bioactive. A new calcium phosphate layer was observed on the surface of the composite after soaking in SBF for only 1 day while osteoblast cells were able to attach and attain normal morphology on the surface of the composite.

  16. Microstructure and tribological properties of 3D needle-punched C/C-SiC brake composites

    NASA Astrophysics Data System (ADS)

    Xiao, Peng; Li, Zhuan; Xiong, Xiang

    2010-04-01

    Carbon fibre reinforced carbon and silicon carbide dual matrix composites (C/C-SiC) show excellent tribological properties and are promising candidates for advanced friction materials. A pressure infiltration/carbonization combined with liquid silicon infiltration was developed for fabricating C/C-SiC composites. The carbon fabric preform was fabricated with the three-dimensional needling method. In the pressure infiltration process, the carbon fibre reinforced plastic was prepared by infiltration of the fabric preform with the furan resin. Then the carbon fibre reinforced plastic was carbonized which was pyrolysed to form a porous carbon/carbon composites. Finally, the porous carbon/carbon was infiltrated with molten silicon to obtain C/C-SiC composites. The composites exhibit excellent friction behavior, including a good stability of brake, and the average dynamic μ is 0.38 and static μ is 0.50, in combination with the linear wear rate of about 5.6 μm cycle -1. Moreover, the friction surface was covered with friction film which is about 10 μm in thickness. These results show that the C/C-SiC brake composites are promising candidates for advanced brake and clutch systems.

  17. Investigation and modeling of the elastic-plastic fracture behavior of continuous woven fabric-reinforced ceramic composites

    SciTech Connect

    Kahl, W.K.

    1997-03-01

    The paper describes a study which attempted to extrapolate meaningful elastic-plastic fracture toughness data from flexure tests of a chemical vapor-infiltrated SiC/Nicalon fiber-reinforced ceramic matrix composite. Fibers in the fabricated composites were pre-coated with pyrolytic carbon to varying thicknesses. In the tests, crack length was not measured and the study employed an estimate procedure, previously used successfully for ductile metals, to derive J-R curve information. Results are presented in normalized load vs. normalized displacements and comparative J{sub Ic} behavior as a function of fiber precoating thickness.

  18. Research Summary of an Additive Manufacturing Technology for the Fabrication of 3D Composites with Tailored Internal Structure

    NASA Astrophysics Data System (ADS)

    Holmes, Larry R.; Riddick, Jaret C.

    2014-01-01

    A novel additive manufacturing technology is used to create micro-composites, which can be tailored for specific end-use applications. The Field-Aided Laminar Composite (FALCom) process uses specifically focused electric fields to align nano- to micro-sized particles into chain-like structures, which are referred to as pseudo-fibers. These pseudo-fibers are then immediately frozen into place by incident ultraviolet radiation on the photopolymer matrix. The pseudo-fibers are arranged by design, and they are used to create three-dimensional composite structures. Multiple filler materials have been evaluated for use in the FALCom system; however, this report describes aluminum micro-particles that are aligned and oriented in an acrylic photopolymer matrix. A description of the technology and a review of experimental processing are shown, and conclusions, as well as, future work are discussed.

  19. Thermo-mechanical Characterization of Metal/Polymer Composite Filaments and Printing Parameter Study for Fused Deposition Modeling in the 3D Printing Process

    NASA Astrophysics Data System (ADS)

    Hwang, Seyeon; Reyes, Edgar I.; Moon, Kyoung-sik; Rumpf, Raymond C.; Kim, Nam Soo

    2015-03-01

    New metal/polymer composite filaments for fused deposition modeling (FDM) processes were developed in order to observe the thermo-mechanical properties of the new filaments. The acrylonitrile butadiene styrene (ABS) thermoplastic was mixed with copper and iron particles. The percent loading of the metal powder was varied to confirm the effects of metal particles on the thermo-mechanical properties of the filament, such as tensile strength and thermal conductivity. The printing parameters such as temperature and fill density were also varied to see the effects of the parameters on the tensile strength of the final product which was made with the FDM process. As a result of this study, it was confirmed that the tensile strength of the composites is decreased by increasing the loading of metal particles. Additionally, the thermal conductivity of the metal/polymer composite filament was improved by increasing the metal content. It is believed that the metal/polymer filament could be used to print metal and large-scale 3-dimensional (3D) structures without any distortion by the thermal expansion of thermoplastics. The material could also be used in 3D printed circuits and electromagnetic structures for shielding and other applications.

  20. Constructing 3D branched nanowire coated macroporous metal oxide electrodes with homogeneous or heterogeneous compositions for efficient solar cells.

    PubMed

    Wu, Wu-Qiang; Xu, Yang-Fan; Rao, Hua-Shang; Feng, Hao-Lin; Su, Cheng-Yong; Kuang, Dai-Bin

    2014-05-05

    Light-harvesting and charge collection have attracted increasing attention in the domain of photovoltaic cells, and can be facilitated dramatically by appropriate design of a photonic nanostructure. However, the applicability of current light-harvesting photoanode materials with single component and/or morphology (such as, particles, spheres, wires, sheets) is still limited by drawbacks such as insufficient electron-hole separation and/or light-trapping. Herein, we introduce a universal method to prepare hierarchical assembly of macroporous material-nanowire coated homogenous or heterogeneous metal oxide composite electrodes (TiO2 -TiO2 , SnO2 -TiO2 , and Zn2 SnO4 -TiO2 ; homogenous refers to a material in which the nanowire and the macroporous material have the same composition, i.e. both are TiO2 . Heterogeneous refers to a material in which the nanowires and the macroporous material have different compositions). The dye-sensitized solar cell based on a TiO2 -macroporous material-TiO2 -nanowire homogenous composition electrode shows an impressive conversion efficiency of 9.51 %, which is much higher than that of pure macroporous material-based photoelectrodes to date.

  1. Analysis of Ablative Performance of C/C Composite Throat Containing Defects Based on X-ray 3D Reconstruction in a Solid Rocket Motor

    NASA Astrophysics Data System (ADS)

    Hui, Wei-Hua; Bao, Fu-Ting; Wei, Xiang-Geng; Liu, Yang

    2015-12-01

    In this paper, a new measuring method of ablation rate was proposed based on X-ray three-dimensional (3D) reconstruction. The ablation of 4-direction carbon/carbon composite nozzles was investigated in the combustion environment of a solid rocket motor, and the macroscopic ablation and linear recession rate were studied through the X-ray 3D reconstruction method. The results showed that the maximum relative error of the X-ray 3D reconstruction was 0.0576%, which met the minimum accuracy of the ablation analysis; along the nozzle axial direction, from convergence segment, throat to expansion segment, the ablation gradually weakened; in terms of defect ablation, the middle ablation was weak, while the ablation in both sides was more serious. In a word, the proposed reconstruction method based on X-ray about C/C nozzle ablation can construct a clear model of ablative nozzle which characterizes the details about micro-cracks, deposition, pores and surface to analyze ablation, so that this method can create the ablation curve in any surface clearly.

  2. Creep and Fatigue in Inert and Vacuum Environments of Woven Sylramic-iBN Melt-Infiltrated Composites (Preprint)

    DTIC Science & Technology

    2011-07-01

    Morscher, G. N., Tensile stress-rupture of SiCf/SiCm minicomposites with carbon and boron nitride interphases at elevated temperatures in air. J. Am...Martinez-Fernandez and G.N. Morscher, “Room and Elevated Temperature Tensile Properties of Single Tow Hi-Nicalon, Carbon Interphase, CVI SiC Matrix...creep and fatigue tests were performed at 1204 °C in a vacuum environment which showed no evidence of oxidation and superior properties to composites

  3. ECM Composition and Rheology Regulate Growth, Motility, and Response to Photodynamic Therapy in 3D Models of Pancreatic Ductal Adenocarcinoma.

    PubMed

    Cramer, Gwendolyn M; Jones, Dustin P; El-Hamidi, Hamid; Celli, Jonathan P

    2017-01-01

    Pancreatic ductal adenocarcinoma is characterized by prominent stromal involvement, which plays complex roles in regulating tumor growth and therapeutic response. The extracellular matrix (ECM)-rich stroma associated with this disease has been implicated as a barrier to drug penetration, although stromal depletion strategies have had mixed clinical success. It remains less clear how interactions with ECM, acting as a biophysical regulator of phenotype, not only a barrier to drug perfusion, regulate susceptibilities and resistance to specific therapies. In this context, an integrative approach is used to evaluate invasive behavior and motility in rheologically characterized ECM as determinants of chemotherapy and photodynamic therapy (PDT) responses. We show that in 3D cultures with ECM conditions that promote invasive progression, response to PDT is markedly enhanced in the most motile ECM-infiltrating populations, whereas the same cells exhibit chemoresistance. Conversely, drug-resistant sublines with enhanced invasive potential were generated to compare differential treatment response in identical ECM conditions, monitored by particle tracking microrheology measurements of matrix remodeling. In both scenarios, ECM-infiltrating cell populations exhibit increased sensitivity to PDT, whether invasion is consequent to selection of chemoresistance, or whether chemoresistance is correlated with acquisition of invasive behavior. However, while ECM-invading, chemoresistant cells exhibit mesenchymal phenotype, induction of EMT in monolayers without ECM was not sufficient to enhance PDT sensitivity, yet does impart chemoresistance as expected. In addition to containing platform development with broader applicability to inform microenvironment-dependent therapeutics, these results reveal the efficacy of PDT for targeting the most aggressive, chemoresistant, invasive pancreatic ductal adenocarcinoma associated with dismal outcomes for this disease.

  4. Matrix Cracking in 3D Orthogonal Melt-Infiltrated SiC/SiC Composites with Various Z-Fiber Types

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Yun, Hee Mann; DiCarlo, James A.

    2003-01-01

    The occurrence of matrix cracks in melt-infiltrated SiC/SiC composites with a 3D orthogonal architecture was determined at room temperature for specimens tested in tension oriented in the X-direction (parallel to Z-bundle weave direction) and Y-direction (perpendicular to Z-bundle weave direction) and Y-direction (perpendicular to Z-bundle weave direction). The fiber-types were Sylramic and Sylramic-IBN in the X and Y-directions and lower modulus ZMI, T300, and rayon in the Z-direction. Acoustic emission (AE) was used to monitor the matrix cracking activity. For Y-direction composites, the AE data was used to determine the exact (+/- 0.25 mm) location where matrix cracks occurred in the 3D orthogonal architecture. This enabled the determination of the stress-dependent matrix crack distributions for small but repeatable matrix rich 'unidirectional' and the matrix poor 'cross-ply' regions within the architecture. It was found that matrix cracking initiated at very low stresses (approx. 40 MPa) in the 'unidirectional' regions for the largest z-direction fiber tow composites. Decreasing the size of the z-fiber bundle, increased the stress for matrix cracking in the 'unidirectional' regions. Matrix cracking in the 'cross-ply' regions always occurred at higher stresses than in 'unidirectional' regions, and the stress-dependent matrix crack distribution of the 'cross-ply' regions was always over a wider stress-range than the 'unidirectional' regions. For composites tested in the X-direction, a lower elastic modulus and a narrower and lower stress-range for matrix cracking were observed compared to composites tested in the Y-direction.

  5. Reducing Uncertainty in the Distribution of Hydrogeologic Units within Volcanic Composite Units of Pahute Mesa Using High-Resolution 3-D Resistivity Methods, Nevada Test Site, Nevada

    USGS Publications Warehouse

    Rodriguez, Brian D.; Sweetkind, Don; Burton, Bethany L.

    2010-01-01

    The U.S. Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) at their Nevada Site Office (NSO) are addressing groundwater contamination resulting from historical underground nuclear testing through the Environmental Management program and, in particular, the Underground Test Area (UGTA) project. From 1951 to 1992, 828 underground nuclear tests were conducted at the Nevada Test Site (NTS) northwest of Las Vegas (DOE UGTA, 2003). Most of these tests were conducted hundreds of feet above the groundwater table; however, more than 200 of the tests were near, or within, the water table. This underground testing was limited to specific areas of the NTS including Pahute Mesa, Rainier Mesa/Shoshone Mountain, Frenchman Flat, and Yucca Flat. Volcanic composite units make up much of the area within the Pahute Mesa Corrective Action Unit (CAU) at the NTS, Nevada. The extent of many of these volcanic composite units extends throughout and south of the primary areas of past underground testing at Pahute and Rainier Mesas. As situated, these units likely influence the rate and direction of groundwater flow and radionuclide transport. Currently, these units are poorly resolved in terms of their hydrologic properties introducing large uncertainties into current CAU-scale flow and transport models. In 2007, the U.S. Geological Survey (USGS), in cooperation with DOE and NNSA-NSO acquired three-dimensional (3-D) tensor magnetotelluric data at the NTS in Area 20 of Pahute Mesa CAU. A total of 20 magnetotelluric recording stations were established at about 600-m spacing on a 3-D array and were tied to ER20-6 well and other nearby well control (fig. 1). The purpose of this survey was to determine if closely spaced 3-D resistivity measurements can be used to characterize the distribution of shallow (600- to 1,500-m-depth range) devitrified rhyolite lava-flow aquifers (LFA) and zeolitic tuff confining units (TCU) in areas of limited drill hole control on

  6. High velocity impact on different hybrid architectures of 2D laminated and 3D warp interlock fabric composite

    NASA Astrophysics Data System (ADS)

    Provost, B.; Boussu, F.; Coutellier, D.; Vallee, D.; Rondot, F.

    2012-08-01

    For decades, conventional amour shield is mainly oriented on metallic materials which are today well-known. Since the use of non conventional threats as IEDs, performances of those protections are required to be upgraded. The expected improvements that manufacturers are looking for are mainly oriented to the weight reduction which is the key parameter to reduce the fuel consumption, increase the payload, and offer more manoeuvrability to vehicles [1]. However, the difficulty is to reduce as cautiously as possible the total mass of the protection solution while ensuring the safety of the vehicle. One of the possible solutions is to use new combinations of materials, able to be more efficient against new threats and lighter than the traditional steel armour. It is in this context that the combination between some well-known ballistic alloys and textile composite material appear as a high potential solution for armour plated protection. Indeed, used as a backing, textile composite material present some interesting properties such as a very low density compared with steel and good behaviour in term of ballistic efficiency. This study proposes to test and compare the behaviour and efficiency of three different textile composite backings.

  7. Facile construction of 3D graphene/MoS2 composites as advanced electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Sun, Tianhua; Li, Zhangpeng; Liu, Xiaohong; Ma, Limin; Wang, Jinqing; Yang, Shengrong

    2016-11-01

    Flower-like molybdenum disulfide (MoS2) microstructures are synthesized based on three-dimensional graphene (3DG) skeleton via a simple and facile one-step hydrothermal method, aiming at constructing series of novel composite electrode materials of 3DG/MoS2 with high electrochemical performances for supercapacitors. The electrochemical properties of the samples are evaluated by cyclic voltammetry and galvanostatic charge/discharge tests. Specifically, the optimal 3DG/MoS2 composite exhibits remarkable performances with a high specific capacitance of 410 F g-1 at a current density of 1 A g-1 and an excellent cycling stability with ca. 80.3% capacitance retention after 10,000 continuous charge-discharge cycles at a high current density of 2 A g-1, making it adaptive for high-performance supercapacitors. The enhanced electrochemical performances can be ascribed to the combination of 3DG and flower-like MoS2, which provides excellent charge transfer network and electrolyte diffusion channels while effectively prevents the collapse, aggregation and morphology change of active materials during charge-discharge process. The results demonstrate that 3DG/MoS2 composite is one of the attractive electrode materials for supercapacitors.

  8. Testing and simulation of a polypropylene-glass fibre reinforced woven composite on a wide range of strain-rates

    NASA Astrophysics Data System (ADS)

    Martin, A.; Othman, R.; Rozycki, P.

    2012-08-01

    Medium costs composites materials are good candidates to develop lightweight and economical shock absorber for the next generation of cars. In this context we are interested in characterising and modelling of Twintex a long glass fiber reinforced polypropylene. Testing will be carried with a standard tensile rig and an original layout using a crossbow/Hopkinson rig. A special attention is made to compression behaviour identification, often neglected but critical for crash absorber behaviour. The model will be checked on the testing specimen and its validity will be discussed.

  9. Modeling multilayer woven fabrics

    NASA Astrophysics Data System (ADS)

    Åström, J. A.; Mäkinen, J. P.; Timonen, J.

    2001-07-01

    A numerical algorithm for nonlinear elastic relaxation of a multilayer woven fabric is introduced and tested. The equilibrium solutions are compared with real samples. An excellent result is obtained in spite of two simplifications: Bending stiffness of the fibers and friction between the fibers are both neglected. The numerical simulation is very fast and cost efficient in the search for optimal fabrics.

  10. Effect of Interface Control on Mode I Interlaminar Fracture Toughness of Woven C/C Composite Laminates

    NASA Astrophysics Data System (ADS)

    Hojo, Masaki; Yamao, Taketoshi; Tanaka, Mototsugu; Ochiai, Shojiro; Iwashita, Norio; Sawada, Yoshihiro

    Effects of fiber/matrix interface and matrix microstructure on the mode I interlaminar fracture toughness of C/C composite materials were investigated by coating bismaleimide-triazine co-polymer (BT-resin) on the surface of carbon fiber and changing the heat-treatment temperature (HTT). For the case of laminates with HTT of 1600°C (carbonized C/C composites), the initial fracture toughness, GIC, was insensitive to BT-resin coating. Moreover, the fracture toughness during crack propagation, GIR, increased by coating BT-resin. On the other hand, both GIC and GIR decreased with BT-resin coating for the laminates with HTT of 2500°C. While both GIC and GIR are insensitive to HTT for laminates without BT-resin coating, they both decreased by increasing HTT for laminates with BT-resin coating. The difference of the effects of interface control and HTT was discussed on the basis of microscopic mechanism consideration. Comparison between in-plane and interlaminar strength indicated the possibility to optimize the interface control.

  11. Cartilage repair and subchondral bone migration using 3D printing osteochondral composites: a one-year-period study in rabbit trochlea.

    PubMed

    Zhang, Weijie; Lian, Qin; Li, Dichen; Wang, Kunzheng; Hao, Dingjun; Bian, Weiguo; He, Jiankang; Jin, Zhongmin

    2014-01-01

    Increasing evidences show that subchondral bone may play a significant role in the repair or progression of cartilage damage in situ. However, the exact change of subchondral bone during osteochondral repair is still poorly understood. In this paper, biphasic osteochondral composite scaffolds were fabricated by 3D printing technology using PEG hydrogel and β-TCP ceramic and then implanted in rabbit trochlea within a critical size defect model. Animals were euthanized at 1, 2, 4, 8, 16, 24, and 52 weeks after implantation. Histological results showed that hyaline-like cartilage formed along with white smooth surface and invisible margin at 24 weeks postoperatively, typical tidemark formation at 52 weeks. The repaired subchondral bone formed from 16 to 52 weeks in a "flow like" manner from surrounding bone to the defect center gradually. Statistical analysis illustrated that both subchondral bone volume and migration area percentage were highly correlated with the gross appearance Wayne score of repaired cartilage. Therefore, subchondral bone migration is related to cartilage repair for critical size osteochondral defects. Furthermore, the subchondral bone remodeling proceeds in a "flow like" manner and repaired cartilage with tidemark implies that the biphasic PEG/β-TCP composites fabricated by 3D printing provides a feasible strategy for osteochondral tissue engineering application.

  12. Cartilage Repair and Subchondral Bone Migration Using 3D Printing Osteochondral Composites: A One-Year-Period Study in Rabbit Trochlea

    PubMed Central

    Li, Dichen; Wang, Kunzheng; Hao, Dingjun; Bian, Weiguo; He, Jiankang; Jin, Zhongmin

    2014-01-01

    Increasing evidences show that subchondral bone may play a significant role in the repair or progression of cartilage damage in situ. However, the exact change of subchondral bone during osteochondral repair is still poorly understood. In this paper, biphasic osteochondral composite scaffolds were fabricated by 3D printing technology using PEG hydrogel and β-TCP ceramic and then implanted in rabbit trochlea within a critical size defect model. Animals were euthanized at 1, 2, 4, 8, 16, 24, and 52 weeks after implantation. Histological results showed that hyaline-like cartilage formed along with white smooth surface and invisible margin at 24 weeks postoperatively, typical tidemark formation at 52 weeks. The repaired subchondral bone formed from 16 to 52 weeks in a “flow like” manner from surrounding bone to the defect center gradually. Statistical analysis illustrated that both subchondral bone volume and migration area percentage were highly correlated with the gross appearance Wayne score of repaired cartilage. Therefore, subchondral bone migration is related to cartilage repair for critical size osteochondral defects. Furthermore, the subchondral bone remodeling proceeds in a “flow like” manner and repaired cartilage with tidemark implies that the biphasic PEG/β-TCP composites fabricated by 3D printing provides a feasible strategy for osteochondral tissue engineering application. PMID:25177697

  13. Fabrication of Compositionally and Topographically Complex Robust Tissue Forms by 3D-Electrochemical Compaction of Collagen

    PubMed Central

    Younesi, Mousa; Islam, Anowarul; Kishore, Vipuil; Panit, Stefi; Akkus, Ozan

    2015-01-01

    Collagen solutions are phase-transformed to mechanically robust shell structures with curviplanar topographies using electrochemically induced pH gradients. The process enables rapid layer-by-layer deposition of collagen-rich mixtures over the entire field simultaneously to obtain compositionally diverse multilayered structures. In-plane tensile strength and modulus of the electrocompacted collagen sheet samples were 5200 -fold and 2300 -fold greater than that of uncompacted collagen samples. Out of plane compression tests showed 27 -fold and fold increase in compressive stress and 46 -fold increase in compressive modulus compared to uncompacted collagen sheets. Cells proliferated 4.9 times faster, and cellular area spread was 2.7 times greater on compacted collagen sheets. Electrocompaction also resulted in 2.9 times greater focal adhesion area than on regular collagen hydrogel. The reported improvements in the cell-matrix interactions with electrocompaction would serve to expedite the population of electrocompacted collagen scaffolds by cells. The capacity of the method to fabricate nonlinear curved topographies with compositional heterogeneous layers is demonstrated by sequential deposition of collagenhydroxyapatite layer over a collagen layer. The complex curved topography of the nasal structure is replicated by the electrochemical compaction method. The presented electrochemical compaction process is an enabling modality which holds significant promise for reconstruction of a wide spectrum of topographically complex systems such as joint surfaces, craniofacial defects, ears, nose or urogenital forms. PMID:26069162

  14. In vitro bone formation by mesenchymal stem cells with 3D collagen/β-TCP composite scaffold.

    PubMed

    Todo, Mitsugu; Arahira, Takaaki

    2013-01-01

    Recent years, various kinds of natural polymers and bioceramics has been used to develop porous scaffolds for bone tissue engineering. Among of them, collagen guarantees good biological conditions, and β-tricalcium phosphate (β-TCP) possesses good oseteoconductivity, cellular adhesion, accelerated differentiation and mechanical property. In this study, rat bone marrow mesenchymal stem cells (rMSC) were cultured in β-TCP/collagen composite scaffolds up to 28 days in order to assess the time-dependent behavior of the extracellular matrix formation and the mechanical performance of the scaffold-cell system. The cell number and ALP activity were evaluated using a spectrophotometric plate reader. Gene expression of osteogenesis was analyzed using the real-time PCR reactions. Compression tests were also conducted periodically by using a conventional testing machine to evaluate the elastic modulus. The increasing behaviors of cell number and ALP activity in the composite scaffold were much better than in the collagen scaffold. The gene expression of osteocalcin and collagen type-I in collagen/β-TCP scaffold was higher than that of the collagen scaffold. The compressive modulus also increased up to 28 days. These results clearly showed that the distribution of micro β-TCP particles is very effective to increase the elastic modulus and promote cell growth.

  15. Effect of degree of crosslinking and polymerization of 3D printable polymer/ionic liquid composites on performance of stretchable piezoresistive sensors

    NASA Astrophysics Data System (ADS)

    Lee, Jeongwoo; Faruk Emon, Md Omar; Vatani, Morteza; Choi, Jae-Won

    2017-03-01

    Ionic liquid (IL)/polymer composites (1-ethyl-3-methyl-imidazolium tetrafluoroborate (EMIMBF4)/2-[[(butylamino)carbonyl]oxy]ethyl acrylate (BACOEA)) were fabricated to use as sensing materials for stretchable piezoresistive tactile sensors. The detectability of the IL/polymer composites was enhanced because the ionic transport properties of EMIMBF4 in the composites were improved by the synergic actions between the coordinate sites generated by the local motion of BACOEA chain segments under enough activation energy. The performance of the piezoresistive sensors was investigated with the degree of crosslinking and polymerization of the IL/polymer composites. As the compressive strain was increased, the distance between two electrodes decreased, and the motion of polymer chains and IL occurred, resulting in a decrease in the electrical resistance of the sensors. We have confirmed that the sensitivity of the sensors are affected by the degree of crosslink and polymerization of the IL/polymer composites. In addition, all of the materials (skins, sensing material, and electrode) used in this study are photo-curable, and thus the stretchable piezoresistive tactile sensors can be successfully fabricated by 3D printing.

  16. Test methods for textile composites

    NASA Technical Reports Server (NTRS)

    Minguet, Pierre J.; Fedro, Mark J.; Gunther, Christian K.

    1994-01-01

    Various test methods commonly used for measuring properties of tape laminate composites were evaluated to determine their suitability for the testing of textile composites. Three different types of textile composites were utilized in this investigation: two-dimensional (2-D) triaxial braids, stitched uniweave fabric, and three-dimensional (3-D) interlock woven fabric. Four 2-D braid architectures, five stitched laminates, and six 3-D woven architectures were tested. All preforms used AS4 fibers and were resin-transfer-molded with Shell RSL-1895 epoxy resin. Ten categories of material properties were investigated: tension, open-hole tension, compression, open-hole compression, in-plane shear, filled-hole tension, bolt bearing, interlaminar tension, interlaminar shear, and interlaminar fracture toughness. Different test methods and specimen sizes were considered for each category of test. Strength and stiffness properties obtained with each of these methods are documented in this report for all the material systems mentioned above.

  17. 3-D ultrastructure and collagen composition of healthy and overloaded human tendon: evidence of tenocyte and matrix buckling

    PubMed Central

    Pingel, Jessica; Lu, Yinhui; Starborg, Tobias; Fredberg, Ulrich; Langberg, Henning; Nedergaard, Anders; Weis, MaryAnn; Eyre, David; Kjaer, Michael; Kadler, Karl E

    2014-01-01

    Achilles tendinopathies display focal tissue thickening with pain and ultrasonography changes. Whilst complete rupture might be expected to induce changes in tissue organization and protein composition, little is known about the consequences of non-rupture-associated tendinopathies, especially with regards to changes in the content of collagen type I and III (the major collagens in tendon), and changes in tendon fibroblast (tenocyte) shape and organization of the extracellular matrix (ECM). To gain new insights, we took biopsies from the tendinopathic region and flanking healthy region of Achilles tendons of six individuals with clinically diagnosed tendinopathy who had no evidence of cholesterol, uric acid and amyloid accumulation. Biochemical analyses of collagen III/I ratio were performed on all six individuals, and electron microscope analysis using transmission electron microscopy and serial block face-scanning electron microscopy were made on two individuals. In the tendinopathic regions, compared with the flanking healthy tissue, we observed: (i) an increase in the ratio of collagen III : I proteins; (ii) buckling of the collagen fascicles in the ECM; (iii) buckling of tenocytes and their nuclei; and (iv) an increase in the ratio of small-diameter : large-diameter collagen fibrils. In summary, load-induced non-rupture tendinopathy in humans is associated with localized biochemical changes, a shift from large-to small-diameter fibrils, buckling of the tendon ECM, and buckling of the cells and their nuclei. PMID:24571576

  18. Europeana and 3D

    NASA Astrophysics Data System (ADS)

    Pletinckx, D.

    2011-09-01

    The current 3D hype creates a lot of interest in 3D. People go to 3D movies, but are we ready to use 3D in our homes, in our offices, in our communication? Are we ready to deliver real 3D to a general public and use interactive 3D in a meaningful way to enjoy, learn, communicate? The CARARE project is realising this for the moment in the domain of monuments and archaeology, so that real 3D of archaeological sites and European monuments will be available to the general public by 2012. There are several aspects to this endeavour. First of all is the technical aspect of flawlessly delivering 3D content over all platforms and operating systems, without installing software. We have currently a working solution in PDF, but HTML5 will probably be the future. Secondly, there is still little knowledge on how to create 3D learning objects, 3D tourist information or 3D scholarly communication. We are still in a prototype phase when it comes to integrate 3D objects in physical or virtual museums. Nevertheless, Europeana has a tremendous potential as a multi-facetted virtual museum. Finally, 3D has a large potential to act as a hub of information, linking to related 2D imagery, texts, video, sound. We describe how to create such rich, explorable 3D objects that can be used intuitively by the generic Europeana user and what metadata is needed to support the semantic linking.

  19. Preparation and photo-induced charge transfer of the composites based on 3D structural CdS nanocrystals and MEH-PPV

    SciTech Connect

    Deng, Dan; Shi, Minmin; Chen, Fei; Chen, Lin; Jiang, Xiaoxia; Chen, Hongzheng

    2010-05-15

    We report the synthesis of 3D structural CdS nanocrystals by a simple biomolecule-assisted hydrothermal process. The CdS nanocrystals are composed of many branched nanorods with the diameter of about 50 nm, and the length of about 250 nm. The phase and crystallographic properties are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffractometry (XRD). The composites based on CdS nanocrystals and poly[2-methoxy-5-(2-ethylhexyloxy-p-phenylenevinylene)] (MEH-PPV) have been prepared by spin-coating of the mixture in the common solvent. The optical properties of the composites are investigated using ultraviolet-visible (UV-Vis) absorption and photoluminescence (PL) spectroscopies. A significant fluorescence quenching of MEH-PPV in the composites is observed at high CdS nanocrystals/MEH-PPV ratios, indicating that the photo-induced charge transfer occurred due to the energy level offset between the donor MEH-PPV and the acceptor CdS nanocrystals. The obvious photovoltaic behavior of the solar cell made from this composite further demonstrates the mentioned photo-induced charge transfer process. (author)

  20. Recent developments in multi-layer flat knitting technology for waste free production of complex shaped 3D-reinforcing structures for composites

    NASA Astrophysics Data System (ADS)

    Trümper, W.; Lin, H.; Callin, T.; Bollengier, Q.; Cherif, C.; Krzywinski, S.

    2016-07-01

    Constantly increasing prices for raw materials and energy as well as the current discourse on the reduction of CO2-emissions places a special emphasis on the advantages of lightweight constructions and its resource conserving production methods. Fibre-reinforced composites are already seeing a number of applications in automobile, energy and mechanical engineering. Future applications within the named areas require greater material and energy efficiency and therefore manufacturing methods for textile preforms and lightweight constructions enabling an optimal arrangement of the reinforcing fibres while in the same time limiting waste to a minimum. One manufacturing method for textile reinforced preforms fulfilling quite many of the named requirements is the multilayer weft knitting technology. Multilayer weft knitted fabrics containing straight reinforcing yarns at least in two directions. The arrangement of these yarns is fixed by the loop yarn. Used yarn material in each knitting row is adaptable e. g. according to the load requirements or for the local integration of sensors. Draping properties of these fabrics can be varied within a great range and through this enabling draping of very complex shaped 3D-preforms without wrinkles from just one uncut fabric. The latest developments at ITM are concentrating on the development of a full production chain considering the 3D-CAD geometry, the load analysis, the generation of machine control programs as well as the development of technology and machines to enable the manufacturing of innovative net shape 3D-multilayer weft knitted fabrics such as complex shaped spacer fabrics and tubular fabrics with biaxial reinforcement.

  1. 3D nanospherical CdxZn1-xS/reduced graphene oxide composites with superior photocatalytic activity and photocorrosion resistance

    NASA Astrophysics Data System (ADS)

    Huang, Meina; Yu, Jianhua; Deng, Changshun; Huang, Yingheng; Fan, Minguang; Li, Bin; Tong, Zhangfa; Zhang, Feiyue; Dong, Lihui

    2016-03-01

    Herein, a series of CdxZn1-xS and sulfide/graphene photocatalysts with 3D nanospherical framework have been successfully fabricated by one-pot solvothermal method for the first time. The morphology and structure of samples were confirmed by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray (EDX) spectrometry, N2 adsorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The as-prepared samples exhibit excellent photocatalytic activities and photocorrosion resistance in the degradation of dyes under visible light. The Cd0.5Zn0.5S/rGO sample shows the most efficient in the photodegradation of methyl orange (MO). It takes about 30 min for degradation completely. The enhanced photocatalytic activity is mainly attributed to the slow photon enhancement of the 3D structure, and the heterojunction between the 3D nanospherical Cd0.5Zn0.5S solid solutions and a high quality 2D rGO support, which can greatly promote the separation of light-induced electrons and holes. Moreover, the large SBET and extended light absorption range also play an important role for improving the photocatalytic activity. The high photocatalytic stability is due to the successful inhibition of the photocorrosion of Cd0.5Zn0.5S/rGO by forming heterojunction between CdS and ZnS, and transferring the photogenerated electrons of Cd0.5Zn0.5S to rGO. The present work can provide rational design of graphene-based photocatalysts with large contact interface and strong interaction between the composites for other application.

  2. High Energy Density Asymmetric Supercapacitor Based on NiOOH/Ni3S2/3D Graphene and Fe3O4/Graphene Composite Electrodes

    PubMed Central

    Lin, Tsung-Wu; Dai, Chao-Shuan; Hung, Kuan-Chung

    2014-01-01

    The application of the composite of Ni3S2 nanoparticles and 3D graphene as a novel cathode material for supercapacitors is systematically investigated in this study. It is found that the electrode capacitance increases by up to 111% after the composite electrode is activated by the consecutive cyclic voltammetry scanning in 1 M KOH. Due to the synergistic effect, the capacitance and the diffusion coefficient of electrolyte ions of the activated composite electrode are ca. 3.7 and 6.5 times higher than those of the Ni3S2 electrode, respectively. Furthermore, the activated composite electrode exhibits an ultrahigh specific capacitance of 3296 F/g and great cycling stability at a current density of 16 A/g. To obtain the reasonable matching of cathode/anode electrodes, the composite of Fe3O4 nanoparticles and chemically reduced graphene oxide (Fe3O4/rGO) is synthesized as the anode material. The Fe3O4/rGO electrode exhibits the specific capacitance of 661 F/g at 1 A/g and excellent rate capability. More importantly, an asymmetric supercapacitor fabricated by two different composite electrodes can be operated reversibly between 0 and 1.6 V and obtain a high specific capacitance of 233 F/g at 5 mV/s, which delivers a maximum energy density of 82.5 Wh/kg at a power density of 930 W/kg. PMID:25449978

  3. Fabrication of nano-Fe3O4 3D structure on carbon fibers as a microwave absorber and EMI shielding composite by modified EPD method

    NASA Astrophysics Data System (ADS)

    Gholampoor, Mahdi; Movassagh-Alanagh, Farid; Salimkhani, Hamed

    2017-02-01

    Recently, electromagnetic interference (EMI) shielding materials have absorbed a lot of attention due to a growing need for application in the area of electronic and wireless devices. In this study, a carbon-based EMI shielding composite was fabricated by electrophoretic deposition of Fe3O4 nano-particles on carbon fibers (CFs) as a 3D structure incorporated with an epoxy resin. Co-precipitation method was employed to synthesize Fe3O4 nano-particles. This as-synthesized Fe3O4 nano-powder was then successfully deposited on CFs using a modified multi-step electrophoretic deposition (EPD) method. The results of structural studies showed that the Fe3O4 nano-particles (25 nm) were successfully and uniformly deposited on CFs. The measured magnetic properties of as-synthesized Fe3O4 nano-powder and nano-Fe3O4/CFs composite showed that the saturation magnetization of bare Fe3O4 was decreased from Ms = 72.3 emu/g to Ms = 33.1 emu/g for nano-Fe3O4/CFs composite and also corecivity of Fe3O4 was increased from Hc = 4.9 Oe to Hc = 168 Oe for composite. The results of microwave absorption tests revealed that the reflection loss (RL) of an epoxy-based nano-Fe3O4/CFs composite are significantly influenced by layer thickness. The maximum RL value of -10.21 dB at 10.12 GHz with an effective absorption bandwidth about 2 GHz was obtained for the sample with the thickness of 2 mm. It also exhibited an EMI shielding performance of -23 dB for whole the frequency range of 8.2-12.4 GHz.

  4. Woven TPS - A New Approach to TPS Design and Manufacturing

    NASA Technical Reports Server (NTRS)

    Feldman, Jay; Stackpoole, Mairead; Venkatapathy, Ethiraj

    2012-01-01

    NASA's Office of the Chief Technologist (OCT) Game Changing Division recently funded an effort to advance a Woven TPS (WTPS) concept. WTPS is a new approach to producing TPS materials that uses precisely engineered 3D weaving techniques to customize material characteristics needed to meet specific missions requirements for protecting space vehicles from the intense heating generated during atmospheric entry. Using WTPS, sustainable, scalable, mission-optimized TPS solutions can be achieved with relatively low life cycle costs compared with the high costs and long development schedules currently associated with material development and certification. WTPS leverages the mature state-of-the-art weaving technology that has evolved from the textile industry to design TPS materials with tailorable performance by varying material composition and properties via the controlled placement of fibers within a woven structure. The resulting material can be designed to perform optimally for a wide range of entry conditions encompassing NASAs current and future mission needs. WTPS enables these optimized TPS designs to be translated precisely into mission-specific, manufactured materials that can substantially increase the efficiency, utility, and robustness of heat shield materials compared to the current state-of-the-art material options. By delivering improved heat shield performance and affordability, this technology will impact all future exploration missions, from the robotic in-situ science missions to Mars, Venus and Saturn to the next generation of human missions. WTPS can change the way NASA develops, certifies, and integrates TPS into mission life cycles - instead of being a mission constraint, TPS will become a mission enabler. It is anticipated that WTPS will have direct impact on SMD, HEOMD and OCT and will be of interest for DoD and COTS applications. This presentation will overview the WTPS concept and present some results from initial testing completed.

  5. 3d-3d correspondence revisited

    DOE PAGES

    Chung, Hee -Joong; Dimofte, Tudor; Gukov, Sergei; ...

    2016-04-21

    In fivebrane compactifications on 3-manifolds, we point out the importance of all flat connections in the proper definition of the effective 3d N = 2 theory. The Lagrangians of some theories with the desired properties can be constructed with the help of homological knot invariants that categorify colored Jones polynomials. Higgsing the full 3d theories constructed this way recovers theories found previously by Dimofte-Gaiotto-Gukov. As a result, we also consider the cutting and gluing of 3-manifolds along smooth boundaries and the role played by all flat connections in this operation.

  6. A binary model of textile composites; 1: Formulation

    SciTech Connect

    Cox, B.N.; Carter, W.C. ); Fleck, N.A. . Engineering Dept.)

    1994-10-01

    This paper presents a finite element model of polymer composites with three-dimensional (3D) reinforcement. The model performs Monte Carlo simulations of failure under monotonic and fatigue loading. The formulation of the model is guided by extensive prior experimental observations of 3D woven composites. Special emphasis is placed on realistic representation of the pattern of reinforcing tows, random irregularity in two positioning, randomness of the strengths of constituent elements, and the mechanics of stress redistribution around sites of local failure. The constitutive properties of model elements (or their distributions) are based on micromechanical models of observed failure events. Material properties that are appropriate analyzed by the model are contrasted with those amenable to much simpler models. Some illustrative model simulations are presented. Prescriptions for the calibration of the model for design and reliability applications and details of its performance in simulating the elastic and damaged regimes of 3D woven composites will appear in subsequent papers.

  7. Application of Three Unit-Cells Models on Mechanical Analysis of 3D Five-Directional and Full Five-Directional Braided Composites

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Xu, Xiwu; Chen, Kang

    2013-10-01

    As new lightweight textile material, 3D five directional and full five directional braided composites (5DBC and F5DBC) have tremendous potential applications in the aerospace industry. Before they are used in primary loading-bearing structures, a rational characterization of their mechanical properties is essential. In this paper, three types of unit-cell models corresponding to the interior, surface and corner regions of 5DBC and F5DBC are proposed. By introducing the reasonable boundary conditions, the effective stiffness properties of these two materials are predicted and compared by the three unit-cells models. The detailed mechanical response characteristic of the three unit-cell models is presented and analyzed in various loading cases. Numerical results show good agreement with experiment data, thus validates the proposed simulation method. Moreover, a parametric study is carried out for analyzing the effects of braiding angle and fiber volume fraction on the elastic properties of 5DBC and F5DBC. The obtained results can help designers to optimize the braided composite structures.

  8. 3D and Education

    NASA Astrophysics Data System (ADS)

    Meulien Ohlmann, Odile

    2013-02-01

    Today the industry offers a chain of 3D products. Learning to "read" and to "create in 3D" becomes an issue of education of primary importance. 25 years professional experience in France, the United States and Germany, Odile Meulien set up a personal method of initiation to 3D creation that entails the spatial/temporal experience of the holographic visual. She will present some different tools and techniques used for this learning, their advantages and disadvantages, programs and issues of educational policies, constraints and expectations related to the development of new techniques for 3D imaging. Although the creation of display holograms is very much reduced compared to the creation of the 90ies, the holographic concept is spreading in all scientific, social, and artistic activities of our present time. She will also raise many questions: What means 3D? Is it communication? Is it perception? How the seeing and none seeing is interferes? What else has to be taken in consideration to communicate in 3D? How to handle the non visible relations of moving objects with subjects? Does this transform our model of exchange with others? What kind of interaction this has with our everyday life? Then come more practical questions: How to learn creating 3D visualization, to learn 3D grammar, 3D language, 3D thinking? What for? At what level? In which matter? for whom?

  9. Facile synthesis of novel 3D nanoflower-like CuxO/multilayer graphene composites for room temperature NOx gas sensor application

    NASA Astrophysics Data System (ADS)

    Yang, Ying; Tian, Chungui; Wang, Jingchao; Sun, Li; Shi, Keying; Zhou, Wei; Fu, Honggang

    2014-06-01

    3D nanoflower-like CuxO/multilayer graphene composites (CuMGCs) have been successfully synthesized as a new type of room temperature NOx gas sensor. Firstly, the expanded graphite (EG) was activated by KOH and many moderate functional groups were generated; secondly, Cu(CH3COO)2 and CTAB underwent full infusion into the interlayers of activated EG (aEG) by means of a vacuum-assisted technique and then reacted with the functional groups of aEG accompanied by the exfoliation of aEG via reflux. Eventually, the 3D nanoflower consisting of 5-9 nm CuxO nanoparticles homogeneously grow in situ on aEG. The KOH activation of EG plays a key role in the uniform formation of CuMGCs. When being used as gas sensors for detection of NOx, the CuMGCs achieved a higher response at room temperature than that of the corresponding CuxO. In detail, the CuMGCs show a higher NOx gas sensing performance with low detection limit of 97 ppb, high gas response of 95.1% and short response time of 9.6 s to 97.0 ppm NOx at room temperature. Meanwhile, the CuMGC sensor presents a favorable linearity, good selectivity and stability. The enhancement of the sensing response is mainly attributed to the improved conductivity of the CuMGCs. A series of Mott-Schottky and EIS measurements demonstrated that the CuMGCs have much higher donor densities than CuxO and can easily capture and migrate electrons from the conduction band, resulting in the enhancement of electrical conductivity.3D nanoflower-like CuxO/multilayer graphene composites (CuMGCs) have been successfully synthesized as a new type of room temperature NOx gas sensor. Firstly, the expanded graphite (EG) was activated by KOH and many moderate functional groups were generated; secondly, Cu(CH3COO)2 and CTAB underwent full infusion into the interlayers of activated EG (aEG) by means of a vacuum-assisted technique and then reacted with the functional groups of aEG accompanied by the exfoliation of aEG via reflux. Eventually, the 3D nanoflower

  10. Method of making carbon-carbon composites

    DOEpatents

    Engle, Glen B.

    1993-01-01

    A process for making 2D and 3D carbon-carbon composites having a combined high crystallinity, high strength, high modulus and high thermal and electrical conductivity. High-modulus/high-strength mesophase derived carbon fibers are woven into a suitable cloth. Layers of this easily graphitizible woven cloth are infiltrated with carbon material to form green composites. The carbonized composite is then impregnated several times with pitch by covering the composite with hot pitch under pressure. The composites are given a heat treatment between each impregnant step to crack up the infiltrated carbon and allow additional pitch to enter the microstructure during the next impregnation cycle. The impregnated composites are then given a final heat treatment in the range 2500.degree. to 3100.degree. C. to fully graphitize the fibers and the matrix carbon. The composites are then infiltrated with pyrolytic carbon by chemical vapor deposition in the range 1000.degree. C. to 1300.degree. C. at a reduced. pressure.

  11. Osteocyte density in woven bone.

    PubMed

    Hernandez, C J; Majeska, R J; Schaffler, M B

    2004-11-01

    Woven bone forms rapidly during tissue growth, following injury and in response to certain anabolic stimuli. Functional differences between woven and lamellar bone may be due, in part, to differences in osteocyte density (cells per unit tissue). Woven bone has been estimated to contain four to eight times more osteocytes than lamellar bone, although primary data to support this assertion are limited. Given recent findings implicating osteocytes as regulators of bone remodeling, bone formation and bone volume, such large differences in osteocyte density between woven and lamellar bone may have important consequences. In this study, we compared the density of osteocyte lacunae (lacunae/mm(2) tissue) in rat lamellar bone with that in woven bone formed under several different circumstances. We found that the lacunar density of lamellar cortical bone in the rat (834+/-83 cells/mm2, mean+/-SD) did not differ significantly from that of periosteal woven bone formed via intramembranous osteogenesis, either in response to mechanical loading (921+/-204 cells/mm2) or in the periosteal buttressing region of the fracture callus (1138+/-168 cells/mm2). In contrast, lacunar density of endochondrally derived woven bone in the center (gap) region of fracture callus was nearly 100% greater (1875+/-270 cells/mm2) than in lamellar cortical bone while lacunar density of primary spongiosa of the growth plate was 40% greater (1674+/-228 cells/mm2) than that in lamellar cancellous bone (1189+/-164). These findings demonstrate that lacunar density in woven bone varies depending on skeletal site and developmental history and appears to be elevated in endochondrally derived woven bone adjacent to marrow space. Given the considerable evidence supporting osteocytes as local initiators of bone remodeling, we suggest that woven bone with increased lacunar density may undergo remodeling at an accelerated rate.

  12. 3D Imaging.

    ERIC Educational Resources Information Center

    Hastings, S. K.

    2002-01-01

    Discusses 3 D imaging as it relates to digital representations in virtual library collections. Highlights include X-ray computed tomography (X-ray CT); the National Science Foundation (NSF) Digital Library Initiatives; output peripherals; image retrieval systems, including metadata; and applications of 3 D imaging for libraries and museums. (LRW)

  13. 3-D multiobservable probabilistic inversion for the compositional and thermal structure of the lithosphere and upper mantle: III. Thermochemical tomography in the Western-Central U.S.

    NASA Astrophysics Data System (ADS)

    Afonso, Juan Carlos; Rawlinson, Nicholas; Yang, Yingjie; Schutt, Derek L.; Jones, Alan G.; Fullea, Javier; Griffin, William L.

    2016-10-01

    We apply a novel 3-D multiobservable probabilistic tomography method that we have recently developed and benchmarked, to directly image the thermochemical structure of the Colorado Plateau and surrounding areas by jointly inverting P wave and S wave teleseismic arrival times, Rayleigh wave dispersion data, Bouguer anomalies, satellite-derived gravity gradients, geoid height, absolute (local and dynamic) elevation, and surface heat flow data. The temperature and compositional structures recovered by our inversion reveal a high level of correlation between recent basaltic magmatism and zones of high temperature and low Mg# (i.e., refertilized mantle) in the lithosphere, consistent with independent geochemical data. However, the lithospheric mantle is overall characterized by a highly heterogeneous thermochemical structure, with only some features correlating well with either Proterozoic and/or Cenozoic crustal structures. This suggests that most of the present-day deep lithospheric architecture reflects the superposition of numerous geodynamic events of different scale and nature to those that created major crustal structures. This is consistent with the complex lithosphere-asthenosphere system that we image, which exhibits a variety of multiscale feedback mechanisms (e.g., small-scale convection, magmatic intrusion, delamination, etc.) driving surface processes. Our results also suggest that most of the present-day elevation in the Colorado Plateau and surrounding regions is the result of thermochemical buoyancy sources within the lithosphere, with dynamic effects (from sublithospheric mantle flow) contributing only locally up to ˜15-35%.

  14. Calculation of effective conductivity of 2D and 3D composite materials with anisotropic constituents and different inclusion shapes in Mathematica

    NASA Astrophysics Data System (ADS)

    Gómez-Muñoz, José Luis; Bravo-Castillero, Julián

    2008-08-01

    The study of the effective properties of composite materials with anisotropic constituents and different inclusion shapes has motivated the development of the Mathematica 6.0 package "CompositeMaterials". This package can be used to calculate the effective anisotropic conductivity tensor of two-phase composites. Any fiber cross section, even percolating ones, can be studied in the 2D composites. "Rectangular Prism" and "Ellipsoidal" inclusion shapes with arbitrary orientations can be investigated in the 3D composites. This package combines the Asymptotic Homogenization Method and the Finite Element Method in order to obtain the effective conductivity tensor. The commands and options of the package are illustrated with two sample applications for two- and three-dimensional composites. Program summaryProgram title:CompositeMaterials Catalogue identifier:AEAU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAU_v1_0.html Program obtainable from:CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions:Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.:132 183 No. of bytes in distributed program, including test data, etc.:1 334 908 Distribution format:tar.gz Programming language:Mathematica 6.0 Computer:Any that can run Mathematica 6.0 and where the open-source free C-programs Triangle ( http://www.cs.cmu.edu/ quake/triangle.html) and TetGen ( http://tetgen.berlios.de/) can be compiled and executed. Tested in Intel Pentium computers. Operating system:Any that can run Mathematica 6.0 and where the open-source free C-programs Triangle ( http://www.cs.cmu.edu/ quake/triangle.html) and TetGen ( http://tetgen.berlios.de/) can be compiled and executed. Tested in Windows XP. RAM:Small two-dimensional calculations require less than 100 MB. Large three-dimensional calculations require 500 MB or more. Classification:7.9 External routines:One Mathematica Add-on and

  15. Development of test methods for textile composites

    NASA Technical Reports Server (NTRS)

    Masters, John E.; Ifju, Peter G.; Fedro, Mark J.

    1993-01-01

    NASA's Advanced Composite Technology (ACT) Program was initiated in 1990 with the purpose of developing less costly composite aircraft structures. A number of innovative materials and processes were evaluated as a part of this effort. Chief among them are composite materials reinforced with textile preforms. These new forms of composite materials bring with them potential testing problems. Methods currently in practice were developed over the years for composite materials made from prepreg tape or simple 2-D woven fabrics. A wide variety of 2-D and 3-D braided, woven, stitched, and knit preforms were suggested for application in the ACT program. The applicability of existing test methods to the wide range of emerging materials bears investigation. The overriding concern is that the values measured are accurate representations of the true material response. The ultimate objective of this work is to establish a set of test methods to evaluate the textile composites developed for the ACT Program.

  16. Dielectric investigation of some woven fabrics

    NASA Astrophysics Data System (ADS)

    Cerovic, Dragana D.; Dojcilovic, Jablan R.; Asanovic, Koviljka A.; Mihajlidi, Tatjana A.

    2009-10-01

    In this paper, we have investigated the temperature dependence of dielectric properties (relative dielectric permeabilities and dielectric tangents of losses) for woven fabrics of hemp, jute, flax, cotton, polyester (PES), cotton-PES mixture, and wool. The measurements have been carried out at a temperature range from -50 to 50 °C in the electric periodic field at a frequency 1 MHz in vacuum. For the same specimens, the values of the dielectric properties have also been measured at an air temperature of 21 °C and at relative humidities of 40%, 60%, and 80%. At different frequencies from 80 kHz to 5 MHz, the dielectric properties have been measured at a relative humidity of 40% and at a temperature of 21 °C. An investigation of the dielectric properties of woven fabrics can provide a better understanding of the relation between the dielectric properties of woven fabrics and the different raw material compositions, temperatures, relative air humidities, and frequencies for specimens. Hence, this investigation helps to improve textile material properties.

  17. Woven Thermal Protection System (Woven TPS) for Extreme Entry Environments

    NASA Video Gallery

    The Woven Thermal Protection System (WTPS) project explores an innovative way to design, develop and manufacture a family of ablative TPS materials using weaving technology and testing them in the ...

  18. Ultrasound - A new approach for non-woven scaffolds investigation

    NASA Astrophysics Data System (ADS)

    Khramtsova, E. A.; Morokov, E. S.; Lukanina, K. I.; Grigoriev, T. E.; Petronyuk, Y. S.; Levin, V. M.

    2016-05-01

    In this study we verified the method of impulse acoustic microscopy as a tool for scaffold evaluation in tissue engineering investigation. Cellulose diacetate (CDA) non-woven 3D scaffold was used as a model object. Scanning electron microscopy and optical microscopy were used as reference methods in order to realize feasibility of acoustic microscopy method in a regenerative medicine field. Direct comparison of the different methods was carried out.

  19. Woven fiber optics.

    PubMed

    Schmidt, A C; Courtney-Pratt, J S; Ross, E A

    1975-02-01

    In this paper we describe how the art of weaving can be applied to fiber optics in order to produce precisely controlled reproducible image guides and image dissectors. As examples of the types of device for which woven fiber optics are applicable, we describe a 3:1 interleaver for use with a cathode-ray tube to produce color images, and a high speed alpha numeric output device. The techniques of weaving fiber optics are discussed in sufficient detail in order to allow for further work. Although, in principle, one might be able to weave glass optical fibers, all the work described here made use of plastic optical fibers 0.25 mm in diameter.

  20. In-Plane Cracking Behavior and Ultimate Strength for 2D Woven and Braided Melt-Infiltrated SiC/SiC Composites Tensile Loaded in Off-Axis Fiber Directions

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Yun, Hee Mann; DiCarlo, James A.

    2007-01-01

    The tensile mechanical properties of ceramic matrix composites (CMC) in directions off the primary axes of the reinforcing fibers are important for architectural design of CMC components that are subjected to multi-axial stress states. In this study, 2D-woven melt-infiltrated (MI) SiC/SiC composite panels with balanced fiber content in the 0 degree and 90 degree directions were tensile loaded in-plane in the 0 degree direction and at 45 degree to this direction. In addition, a 2D triaxially-braided MI composite panel with balanced fiber content in the plus or minus 67 degree bias directions and reduced fiber content in the axial direction was tensile loaded perpendicular to the axial direction tows (i.e., 23 degrees from the bias fibers). Stress-strain behavior, acoustic emission, and optical microscopy were used to quantify stress-dependent matrix cracking and ultimate strength in the panels. It was observed that both off-axis loaded panels displayed higher composite onset stresses for through-thickness matrix cracking than the 2D-woven 0/90 panels loaded in the primary 0 degree direction. These improvements for off-axis cracking strength can in part be attributed to higher effective fiber fractions in the loading direction, which in turn reduces internal stresses on critical matrix flaws for a given composite stress. Also for the 0/90 panel loaded in the 45 degree direction, an improved distribution of matrix flaws existed due to the absence of fiber tows perpendicular to the loading direction. In addition, for the +67/0/-67 braided panel, the axial tows perpendicular to the loading direction were not only low in volume fraction, but were also were well separated from one another. Both off-axis oriented panels also showed relatively good ultimate tensile strength when compared to other off-axis oriented composites in the literature, both on an absolute strength basis as well as when normalized by the average fiber strength within the composites. Initial

  1. AE3D

    SciTech Connect

    Spong, Donald A

    2016-06-20

    AE3D solves for the shear Alfven eigenmodes and eigenfrequencies in a torodal magnetic fusion confinement device. The configuration can be either 2D (e.g. tokamak, reversed field pinch) or 3D (e.g. stellarator, helical reversed field pinch, tokamak with ripple). The equations solved are based on a reduced MHD model and sound wave coupling effects are not currently included.

  2. Thermal and Structural Performance of Woven Carbon Cloth For Adaptive Deployable Entry and Placement Technology

    NASA Technical Reports Server (NTRS)

    Arnold, James O.; Peterson, Keith H.; Yount, Bryan C.; Schneider, Nigel; Chavez-Garcia, Jose

    2013-01-01

    Arcjet testing and analysis of a three-dimensional (3D) woven carbon fabric has shown that it can be used as a thermal protection system and as a load bearing structural component for a low ballistic coefficient hypersonic decelerator called ADEPT (Adaptive Deployable Entry and Placement Technology). Results of arcjet tests proved that the 3D woven carbon fabric can withstand flight-like heating while under flight-like biaxial mechanical loads representative of those encountered during shallow entry flight path angles into the atmosphere of Venus. Importantly, the arcjet test results have been used to extend a preliminary material thermal response model based on previous testing of the same 3D woven carbon fabric under uni-axial mechanical loading.

  3. Adhesion and growth of human bone marrow mesenchymal stem cells on precise-geometry 3D organic-inorganic composite scaffolds for bone repair.

    PubMed

    Chatzinikolaidou, Maria; Rekstyte, Sima; Danilevicius, Paulius; Pontikoglou, Charalampos; Papadaki, Helen; Farsari, Maria; Vamvakaki, Maria

    2015-03-01

    Engineering biomaterial scaffolds that promote attachment and growth of mesenchymal stem cells in three dimensions is a crucial parameter for successful bone tissue engineering. Towards this direction, a lot of research effort has focused recently into the development of three-dimensional porous scaffolds, aiming to elicit positive cellular behavior. However, the fabrication of three-dimensional tissue scaffolds with a precise geometry and complex micro- and nano-features, supporting cell in-growth remains a challenge. In this study we report on a positive cellular response of human bone marrow-derived (BM) mesenchymal stem cells (MSCs) onto hybrid material scaffolds consisting of methacryloxypropyl trimethoxysilane, zirconium propoxide, and 2-(dimethylamino)ethyl methacrylate (DMAEMA). First, we use Direct fs Laser Writing, a 3D scaffolding technology to fabricate the complex structures. Subsequently, we investigate the morphology, viability and proliferation of BM-MSCs onto the hybrid scaffolds and examine the cellular response from different donors. Finally, we explore the effect of the materials' chemical composition on cell proliferation, employing three different material surfaces: (i) a hybrid consisting of methacryloxypropyl trimethoxysilane, zirconium propoxide and 50mol% DMAEMA, (ii) a hybrid material comprising methacryloxypropyl trimethoxysilane and zirconium propoxide, and (iii) a purely organic polyDMAEMA. Our results show a strong adhesion of BM-MSCs onto the hybrid material containing 50% DMAEMA from the first 2h after seeding, and up to several days, and a proliferation increase after 14 and 21days, similar to the polystyrene control, independent of cell donor. These findings support the potential use of our proposed cell-material combination in bone tissue engineering.

  4. Electrochemical and bio-sensing platform based on a novel 3D Cu nano-flowers/layered MoS₂ composite.

    PubMed

    Lin, Xiaoyun; Ni, Yongnian; Kokot, Serge

    2016-05-15

    A novel 3D nano-flower-like Cu/multi-layer molybdenum disulfide composite (CuNFs/MoS2) modified glassy carbon electrode (GCE) has been successfully constructed. It was a highly sensitive and selective non-enzymatic hydrogen peroxide (H2O2) and glucose biosensor. The morphology of the obtained CuNFs-MoS2 nano-particles was investigated with the use of a scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). The physicochemical properties of the modified electrode were characterized at each of the construction stages with the use of an electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The new sensor combined the advantages of MoS2 and CuNFs, and exhibited high electro-catalytic activity toward H2O2 and glucose. Quantitative analysis of H2O2 and glucose was carried out with the use of the amperometric i-t method. Linear ranges were obtained between 0.04-1.88 μM and 1.88-35.6 μM for H2O2 and 1-20 μM and 20-70 μM for glucose, and their corresponding limits of detection (LOD) were 0.021 μM and 0.32 μM. This novel sensor was successfully applied for the quantitative analysis of H2O2 in tap water and glucose in human serum samples.

  5. 3-D Seismic Interpretation

    NASA Astrophysics Data System (ADS)

    Moore, Gregory F.

    2009-05-01

    This volume is a brief introduction aimed at those who wish to gain a basic and relatively quick understanding of the interpretation of three-dimensional (3-D) seismic reflection data. The book is well written, clearly illustrated, and easy to follow. Enough elementary mathematics are presented for a basic understanding of seismic methods, but more complex mathematical derivations are avoided. References are listed for readers interested in more advanced explanations. After a brief introduction, the book logically begins with a succinct chapter on modern 3-D seismic data acquisition and processing. Standard 3-D acquisition methods are presented, and an appendix expands on more recent acquisition techniques, such as multiple-azimuth and wide-azimuth acquisition. Although this chapter covers the basics of standard time processing quite well, there is only a single sentence about prestack depth imaging, and anisotropic processing is not mentioned at all, even though both techniques are now becoming standard.

  6. Radiochromic 3D Detectors

    NASA Astrophysics Data System (ADS)

    Oldham, Mark

    2015-01-01

    Radiochromic materials exhibit a colour change when exposed to ionising radiation. Radiochromic film has been used for clinical dosimetry for many years and increasingly so recently, as films of higher sensitivities have become available. The two principle advantages of radiochromic dosimetry include greater tissue equivalence (radiologically) and the lack of requirement for development of the colour change. In a radiochromic material, the colour change arises direct from ionising interactions affecting dye molecules, without requiring any latent chemical, optical or thermal development, with important implications for increased accuracy and convenience. It is only relatively recently however, that 3D radiochromic dosimetry has become possible. In this article we review recent developments and the current state-of-the-art of 3D radiochromic dosimetry, and the potential for a more comprehensive solution for the verification of complex radiation therapy treatments, and 3D dose measurement in general.

  7. Bootstrapping 3D fermions

    DOE PAGES

    Iliesiu, Luca; Kos, Filip; Poland, David; ...

    2016-03-17

    We study the conformal bootstrap for a 4-point function of fermions <ψψψψ> in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge CT. We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N. Finally, we also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.

  8. Bootstrapping 3D fermions

    SciTech Connect

    Iliesiu, Luca; Kos, Filip; Poland, David; Pufu, Silviu S.; Simmons-Duffin, David; Yacoby, Ran

    2016-03-17

    We study the conformal bootstrap for a 4-point function of fermions <ψψψψ> in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge CT. We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N. Finally, we also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.

  9. Stochastic Nonlinear Response of Woven CMCs

    NASA Technical Reports Server (NTRS)

    Kuang, C. Liu; Arnold, Steven M.

    2013-01-01

    It is well known that failure of a material is a locally driven event. In the case of ceramic matrix composites (CMCs), significant variations in the microstructure of the composite exist and their significance on both deformation and life response need to be assessed. Examples of these variations include changes in the fiber tow shape, tow shifting/nesting and voids within and between tows. In the present work, the influence of scale specific architectural features of woven ceramic composite are examined stochastically at both the macroscale (woven repeating unit cell (RUC)) and structural scale (idealized using multiple RUCs). The recently developed MultiScale Generalized Method of Cells methodology is used to determine the overall deformation response, proportional elastic limit (first matrix cracking), and failure under tensile loading conditions and associated probability distribution functions. Prior results showed that the most critical architectural parameter to account for is weave void shape and content with other parameters being less in severity. Current results show that statistically only the post-elastic limit region (secondary hardening modulus and ultimate tensile strength) is impacted by local uncertainties both at the macro and structural level.

  10. Venus in 3D

    NASA Technical Reports Server (NTRS)

    Plaut, Jeffrey J.

    1993-01-01

    Stereographic images of the surface of Venus which enable geologists to reconstruct the details of the planet's evolution are discussed. The 120-meter resolution of these 3D images make it possible to construct digital topographic maps from which precise measurements can be made of the heights, depths, slopes, and volumes of geologic structures.

  11. 3D photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Carson, Jeffrey J. L.; Roumeliotis, Michael; Chaudhary, Govind; Stodilka, Robert Z.; Anastasio, Mark A.

    2010-06-01

    Our group has concentrated on development of a 3D photoacoustic imaging system for biomedical imaging research. The technology employs a sparse parallel detection scheme and specialized reconstruction software to obtain 3D optical images using a single laser pulse. With the technology we have been able to capture 3D movies of translating point targets and rotating line targets. The current limitation of our 3D photoacoustic imaging approach is its inability ability to reconstruct complex objects in the field of view. This is primarily due to the relatively small number of projections used to reconstruct objects. However, in many photoacoustic imaging situations, only a few objects may be present in the field of view and these objects may have very high contrast compared to background. That is, the objects have sparse properties. Therefore, our work had two objectives: (i) to utilize mathematical tools to evaluate 3D photoacoustic imaging performance, and (ii) to test image reconstruction algorithms that prefer sparseness in the reconstructed images. Our approach was to utilize singular value decomposition techniques to study the imaging operator of the system and evaluate the complexity of objects that could potentially be reconstructed. We also compared the performance of two image reconstruction algorithms (algebraic reconstruction and l1-norm techniques) at reconstructing objects of increasing sparseness. We observed that for a 15-element detection scheme, the number of measureable singular vectors representative of the imaging operator was consistent with the demonstrated ability to reconstruct point and line targets in the field of view. We also observed that the l1-norm reconstruction technique, which is known to prefer sparseness in reconstructed images, was superior to the algebraic reconstruction technique. Based on these findings, we concluded (i) that singular value decomposition of the imaging operator provides valuable insight into the capabilities of

  12. Deployable robotic woven wire structures and joints for space applications

    NASA Technical Reports Server (NTRS)

    Shahinpoor, MO; Smith, Bradford

    1991-01-01

    Deployable robotic structures are basically expandable and contractable structures that may be transported or launched to space in a compact form. These structures may then be intelligently deployed by suitable actuators. The deployment may also be done by means of either airbag or spring-loaded typed mechanisms. The actuators may be pneumatic, hydraulic, ball-screw type, or electromagnetic. The means to trigger actuation may be on-board EPROMS, programmable logic controllers (PLCs) that trigger actuation based on some input caused by the placement of the structure in the space environment. The actuation may also be performed remotely by suitable remote triggering devices. Several deployable woven wire structures are examined. These woven wire structures possess a unique form of joint, the woven wire joint, which is capable of moving and changing its position and orientation with respect to the structure itself. Due to the highly dynamic and articulate nature of these joints the 3-D structures built using them are uniquely and highly expandable, deployable, and dynamic. The 3-D structure naturally gives rise to a new generation of deployable three-dimensional spatial structures.

  13. Personnel occupied woven envelope robot

    NASA Technical Reports Server (NTRS)

    Wessling, F. C.

    1986-01-01

    The use of nonmetallic or fabric structures for space application is considered. The following structures are suggested: (1) unpressurized space hangars; (2) extendable tunnels for soft docking; and (3) manned habitat for space stations, storage facilities, and work structures. The uses of the tunnel as a passageway: for personnel and equipment, eliminating extravehicular activity, for access to a control cabin on a space crane and between free flyers and the space station are outlined. The personnal occupied woven envelope robot (POWER) device is shown. The woven envelope (tunnel) acts as part of the boom of a crane. Potential applications of POWER are outlined. Several possible deflection mechanisms and design criteria are determined.

  14. Phase I/II Trial of Autologous Bone Marrow Stem Cell Transplantation with a Three-Dimensional Woven-Fabric Scaffold for Periodontitis

    PubMed Central

    Baba, Shunsuke; Komuro, Akira; Yotsui, Yoritaka; Umeda, Makoto; Shimuzutani, Kimishige; Nakamura, Sayaka

    2016-01-01

    Regenerative medicine is emerging as a promising option, but the potential of autologous stem cells has not been investigated well in clinical settings of periodontal treatment. In this clinical study, we evaluated the safety and efficacy of a new regenerative therapy based on the surgical implantation of autologous mesenchymal stem cells (MSCs) with a biodegradable three-dimensional (3D) woven-fabric composite scaffold and platelet-rich plasma (PRP). Ten patients with periodontitis, who required a surgical procedure for intrabony defects, were enrolled in phase I/II trial. Once MSCs were implanted in each periodontal intrabony defect, the patients were monitored during 36 months for a medical exam including laboratory tests of blood and urine samples, changes in clinical attachment level, pocket depth, and linear bone growth (LBG). All three parameters improved significantly during the entire follow-up period (p < 0.0001), leading to an average LBG of 4.7 mm after 36 months. Clinical mobility measured by Periotest showed a decreasing trend after the surgery. No clinical safety problems attributable to the investigational MSCs were identified. This clinical trial suggests that the stem cell therapy using MSCs-PRP/3D woven-fabric composite scaffold may constitute a novel safe and effective regenerative treatment option for periodontitis. PMID:27990164

  15. Twin Peaks - 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The two hills in the distance, approximately one to two kilometers away, have been dubbed the 'Twin Peaks' and are of great interest to Pathfinder scientists as objects of future study. 3D glasses are necessary to identify surface detail. The white areas on the left hill, called the 'Ski Run' by scientists, may have been formed by hydrologic processes.

    The IMP is a stereo imaging system with color capability provided by 24 selectable filters -- twelve filters per 'eye.

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  16. 3D and beyond

    NASA Astrophysics Data System (ADS)

    Fung, Y. C.

    1995-05-01

    This conference on physiology and function covers a wide range of subjects, including the vasculature and blood flow, the flow of gas, water, and blood in the lung, the neurological structure and function, the modeling, and the motion and mechanics of organs. Many technologies are discussed. I believe that the list would include a robotic photographer, to hold the optical equipment in a precisely controlled way to obtain the images for the user. Why are 3D images needed? They are to achieve certain objectives through measurements of some objects. For example, in order to improve performance in sports or beauty of a person, we measure the form, dimensions, appearance, and movements.

  17. 3D Audio System

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Ames Research Center research into virtual reality led to the development of the Convolvotron, a high speed digital audio processing system that delivers three-dimensional sound over headphones. It consists of a two-card set designed for use with a personal computer. The Convolvotron's primary application is presentation of 3D audio signals over headphones. Four independent sound sources are filtered with large time-varying filters that compensate for motion. The perceived location of the sound remains constant. Possible applications are in air traffic control towers or airplane cockpits, hearing and perception research and virtual reality development.

  18. Quon 3D language for quantum information

    PubMed Central

    Liu, Zhengwei; Wozniakowski, Alex; Jaffe, Arthur M.

    2017-01-01

    We present a 3D topological picture-language for quantum information. Our approach combines charged excitations carried by strings, with topological properties that arise from embedding the strings in the interior of a 3D manifold with boundary. A quon is a composite that acts as a particle. Specifically, a quon is a hemisphere containing a neutral pair of open strings with opposite charge. We interpret multiquons and their transformations in a natural way. We obtain a type of relation, a string–genus “joint relation,” involving both a string and the 3D manifold. We use the joint relation to obtain a topological interpretation of the C∗-Hopf algebra relations, which are widely used in tensor networks. We obtain a 3D representation of the controlled NOT (CNOT) gate that is considerably simpler than earlier work, and a 3D topological protocol for teleportation. PMID:28167790

  19. 3D Surgical Simulation

    PubMed Central

    Cevidanes, Lucia; Tucker, Scott; Styner, Martin; Kim, Hyungmin; Chapuis, Jonas; Reyes, Mauricio; Proffit, William; Turvey, Timothy; Jaskolka, Michael

    2009-01-01

    This paper discusses the development of methods for computer-aided jaw surgery. Computer-aided jaw surgery allows us to incorporate the high level of precision necessary for transferring virtual plans into the operating room. We also present a complete computer-aided surgery (CAS) system developed in close collaboration with surgeons. Surgery planning and simulation include construction of 3D surface models from Cone-beam CT (CBCT), dynamic cephalometry, semi-automatic mirroring, interactive cutting of bone and bony segment repositioning. A virtual setup can be used to manufacture positioning splints for intra-operative guidance. The system provides further intra-operative assistance with the help of a computer display showing jaw positions and 3D positioning guides updated in real-time during the surgical procedure. The CAS system aids in dealing with complex cases with benefits for the patient, with surgical practice, and for orthodontic finishing. Advanced software tools for diagnosis and treatment planning allow preparation of detailed operative plans, osteotomy repositioning, bone reconstructions, surgical resident training and assessing the difficulties of the surgical procedures prior to the surgery. CAS has the potential to make the elaboration of the surgical plan a more flexible process, increase the level of detail and accuracy of the plan, yield higher operative precision and control, and enhance documentation of cases. Supported by NIDCR DE017727, and DE018962 PMID:20816308

  20. Martian terrain - 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    An area of rocky terrain near the landing site of the Sagan Memorial Station can be seen in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. This image is part of a 3D 'monster' panorama of the area surrounding the landing site.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  1. SRM nozzle design breakthroughs with advanced composite materials

    NASA Astrophysics Data System (ADS)

    Berdoyes, Michel

    1993-06-01

    The weight reduction-related performance and cost of the Space Shuttle's Solid Rocket Motor (SRM) units' critical nozzle components are undergoing revolutionary improvements through the use of 3D-woven carbon/carbon and carbon/alumina composite materials. These can be used to fabricate the SRM's nozzle throat nondegradable insulators, thermostructural insulator, and exit cones. Additional developments are noted among nozzle-related structural components for additional rocket propulsion systems, including a three-piece extendible nozzle.

  2. An aerial 3D printing test mission

    NASA Astrophysics Data System (ADS)

    Hirsch, Michael; McGuire, Thomas; Parsons, Michael; Leake, Skye; Straub, Jeremy

    2016-05-01

    This paper provides an overview of an aerial 3D printing technology, its development and its testing. This technology is potentially useful in its own right. In addition, this work advances the development of a related in-space 3D printing technology. A series of aerial 3D printing test missions, used to test the aerial printing technology, are discussed. Through completing these test missions, the design for an in-space 3D printer may be advanced. The current design for the in-space 3D printer involves focusing thermal energy to heat an extrusion head and allow for the extrusion of molten print material. Plastics can be used as well as composites including metal, allowing for the extrusion of conductive material. A variety of experiments will be used to test this initial 3D printer design. High altitude balloons will be used to test the effects of microgravity on 3D printing, as well as parabolic flight tests. Zero pressure balloons can be used to test the effect of long 3D printing missions subjected to low temperatures. Vacuum chambers will be used to test 3D printing in a vacuum environment. The results will be used to adapt a current prototype of an in-space 3D printer. Then, a small scale prototype can be sent into low-Earth orbit as a 3-U cube satellite. With the ability to 3D print in space demonstrated, future missions can launch production hardware through which the sustainability and durability of structures in space will be greatly improved.

  3. Explicit 3-D Hydrodynamic FEM Program

    SciTech Connect

    2000-11-07

    DYNA3D is a nonlinear explicit finite element code for analyzing 3-D structures and solid continuum. The code is vectorized and available on several computer platforms. The element library includes continuum, shell, beam, truss and spring/damper elements to allow maximum flexibility in modeling physical problems. Many materials are available to represent a wide range of material behavior, including elasticity, plasticity, composites, thermal effects and rate dependence. In addition, DYNA3D has a sophisticated contact interface capability, including frictional sliding, single surface contact and automatic contact generation.

  4. Meshing Preprocessor for the Mesoscopic 3D Finite Element Simulation of 2D and Interlock Fabric Deformation

    NASA Astrophysics Data System (ADS)

    Wendling, A.; Daniel, J. L.; Hivet, G.; Vidal-Sallé, E.; Boisse, P.

    2015-12-01

    Numerical simulation is a powerful tool to predict the mechanical behavior and the feasibility of composite parts. Among the available numerical approaches, as far as woven reinforced composites are concerned, 3D finite element simulation at the mesoscopic scale leads to a good compromise between realism and complexity. At this scale, the fibrous reinforcement is modeled by an interlacement of yarns assumed to be homogeneous that have to be accurately represented. Among the numerous issues induced by these simulations, the first one consists in providing a representative meshed geometrical model of the unit cell at the mesoscopic scale. The second one consists in enabling a fast data input in the finite element software (contacts definition, boundary conditions, elements reorientation, etc.) so as to obtain results within reasonable time. Based on parameterized 3D CAD modeling tool of unit-cells of dry fabrics already developed, this paper presents an efficient strategy which permits an automated meshing of the models with 3D hexahedral elements and to accelerate of several orders of magnitude the simulation data input. Finally, the overall modeling strategy is illustrated by examples of finite element simulation of the mechanical behavior of fabrics.

  5. 3D field harmonics

    SciTech Connect

    Caspi, S.; Helm, M.; Laslett, L.J.

    1991-03-30

    We have developed an harmonic representation for the three dimensional field components within the windings of accelerator magnets. The form by which the field is presented is suitable for interfacing with other codes that make use of the 3D field components (particle tracking and stability). The field components can be calculated with high precision and reduced cup time at any location (r,{theta},z) inside the magnet bore. The same conductor geometry which is used to simulate line currents is also used in CAD with modifications more readily available. It is our hope that the format used here for magnetic fields can be used not only as a means of delivering fields but also as a way by which beam dynamics can suggest correction to the conductor geometry. 5 refs., 70 figs.

  6. A Study of Strength Transfer from tow to Textile Composite Using Different Reinforcement Architectures

    NASA Astrophysics Data System (ADS)

    Cristian, Irina; Nauman, Saad; Boussu, Francois; Koncar, Vladan

    2012-06-01

    The paper proposes an experimental and analytical approach of designing composites with the predetermined ultimate strength, reinforced with warp interlock fabrics. In order to better understand the phenomena of transfer of tensile properties from a tow to the composite, intermediate phases of composite manufacturing have also been taken into account and tensile properties of tows taken from the loom and the woven reinforcements have also been tested. Process of transfer of mechanical properties of raw materials to the final product (composite) depends on various structural factors. Here the influence of weave structure, which ultimately influences crimp has been studied. A strength transfer coefficient has been proposed which helps in estimating the influence of architectural parameters on 3D woven composites. 3 woven interlock reinforcements were woven to form composites. The coefficients of strength transfer were calculated for these three variants. The structural parameters were kept the same for these three reinforcements except for the weave structure. In was found that the phenomenon of strength transfer from tow to composite is negatively influenced by the crimp. In general the strength transfer coefficients have higher values for dry reinforcements and afterwards due to resin impregnation the values drop.

  7. Stress-Dependent Matrix Cracking in 2D Woven SiC-Fiber Reinforced Melt-Infiltrated SiC Matrix Composites

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.

    2003-01-01

    The matrix cracking of a variety of SiC/SiC composites has been characterized for a wide range of constituent variation. These composites were fabricated by the 2-dimensional lay-up of 0/90 five-harness satin fabric consisting of Sylramic fiber tows that were then chemical vapor infiltrated (CVI) with BN, CVI with SiC, slurry infiltrated with SiC particles followed by molten infiltration of Si. The composites varied in number of plies, the number of tows per length, thickness, and the size of the tows. This resulted in composites with a fiber volume fraction in the loading direction that ranged from 0.12 to 0.20. Matrix cracking was monitored with modal acoustic emission in order to estimate the stress-dependent distribution of matrix cracks. It was found that the general matrix crack properties of this system could be fairly well characterized by assuming that no matrix cracks originated in the load-bearing fiber, interphase, chemical vapor infiltrated Sic tow-minicomposites, i.e., all matrix cracks originate in the 90 degree tow-minicomposites or the large unreinforced Sic-Si matrix regions. Also, it was determined that the larger tow size composites had a much narrower stress range for matrix cracking compared to the standard tow size composites.

  8. Intraoral 3D scanner

    NASA Astrophysics Data System (ADS)

    Kühmstedt, Peter; Bräuer-Burchardt, Christian; Munkelt, Christoph; Heinze, Matthias; Palme, Martin; Schmidt, Ingo; Hintersehr, Josef; Notni, Gunther

    2007-09-01

    Here a new set-up of a 3D-scanning system for CAD/CAM in dental industry is proposed. The system is designed for direct scanning of the dental preparations within the mouth. The measuring process is based on phase correlation technique in combination with fast fringe projection in a stereo arrangement. The novelty in the approach is characterized by the following features: A phase correlation between the phase values of the images of two cameras is used for the co-ordinate calculation. This works contrary to the usage of only phase values (phasogrammetry) or classical triangulation (phase values and camera image co-ordinate values) for the determination of the co-ordinates. The main advantage of the method is that the absolute value of the phase at each point does not directly determine the coordinate. Thus errors in the determination of the co-ordinates are prevented. Furthermore, using the epipolar geometry of the stereo-like arrangement the phase unwrapping problem of fringe analysis can be solved. The endoscope like measurement system contains one projection and two camera channels for illumination and observation of the object, respectively. The new system has a measurement field of nearly 25mm × 15mm. The user can measure two or three teeth at one time. So the system can by used for scanning of single tooth up to bridges preparations. In the paper the first realization of the intraoral scanner is described.

  9. 'Diamond' in 3-D

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 3-D, microscopic imager mosaic of a target area on a rock called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  10. Prominent rocks - 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Many prominent rocks near the Sagan Memorial Station are featured in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. Wedge is at lower left; Shark, Half-Dome, and Pumpkin are at center. Flat Top, about four inches high, is at lower right. The horizon in the distance is one to two kilometers away.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  11. Woven-Yarn Thermoelectric Textiles.

    PubMed

    Lee, Jae Ah; Aliev, Ali E; Bykova, Julia S; de Andrade, Mônica Jung; Kim, Daeyoung; Sim, Hyeon Jun; Lepró, Xavier; Zakhidov, Anvar A; Lee, Jeong-Bong; Spinks, Geoffrey M; Roth, Siegmar; Kim, Seon Jeong; Baughman, Ray H

    2016-07-01

    The fabrication and characterization of highly flexible textiles are reported. These textiles can harvest thermal energy from temperature gradients in the desirable through-thickness direction. The tiger yarns containing n- and p-type segments are woven to provide textiles containing n-p junctions. A high power output of up to 8.6 W m(-2) is obtained for a temperature difference of 200 °C.

  12. Designing Biomaterials for 3D Printing.

    PubMed

    Guvendiren, Murat; Molde, Joseph; Soares, Rosane M D; Kohn, Joachim

    2016-10-10

    Three-dimensional (3D) printing is becoming an increasingly common technique to fabricate scaffolds and devices for tissue engineering applications. This is due to the potential of 3D printing to provide patient-specific designs, high structural complexity, rapid on-demand fabrication at a low-cost. One of the major bottlenecks that limits the widespread acceptance of 3D printing in biomanufacturing is the lack of diversity in "biomaterial inks". Printability of a biomaterial is determined by the printing technique. Although a wide range of biomaterial inks including polymers, ceramics, hydrogels and composites have been developed, the field is still struggling with processing of these materials into self-supporting devices with tunable mechanics, degradation, and bioactivity. This review aims to highlight the past and recent advances in biomaterial ink development and design considerations moving forward. A brief overview of 3D printing technologies focusing on ink design parameters is also included.

  13. Regoliths in 3-D

    NASA Technical Reports Server (NTRS)

    Grant, John; Cheng, Andrew; Delamere, Allen; Gorevan, Steven; Korotev, Randy; McKay, David; Schmitt, Harrison; Zarnecki, John

    1996-01-01

    A planetary regolith is any layer of fragments, unconsolidated material that may or may not be textually or compositionally altered relative to underlying substrate and occurs on the outer surface of a solar system body. This includes fragmented material from volcanic, sedimentary, and meteoritic infall sources, and derived by any process (e.g. impact and all other endogenic or exogenic processes). Many measurements that can be made from orbit or from Earth-based observations provide information only about the uppermost portions of a regolith and not the underlying substrate(s). Thus an understanding of the formation processes, physical properties, composition, and evolution of planetary regoliths is essential in answering scientific questions posed by the Committee on Planetary and Lunar Exploration (COMPLEX). This paper provides examples of measurements required to answer these critical science questions.

  14. Aerosol-Assisted Heteroassembly of Oxide Nanocrystals and Carbon Nanotubes into 3D Mesoporous Composites for High-Rate Electrochemical Energy Storage.

    PubMed

    Jia, Xilai; Zhu, Xiao; Cheng, Yanhua; Chen, Zheng; Ning, Guoqing; Lu, Yunfeng; Wei, Fei

    2015-07-01

    Nanostructured composites built from ordinary building units have attracted much attention because of their collective properties for critical applications. Herein, we have demonstrated the heteroassembly of carbon nanotubes and oxide nanocrystals using an aerosol spray method to prepare nanostructured mesoporous composites for electrochemical energy storage. The designed composite architectures show high conductivity and hierarchically structured mesopores, which achieve rapid electron and ion transport in electrodes. Therefore, as-synthesized carbon nanotube/TiO2 electrodes exhibit high rate performance through rapid Li(+) intercalation, making them suitable for ultrafast energy storage devices. Moreover, the synthesis process provides a broadly applicable method to achieve the heteroassembly of vast low-dimensional building blocks for many important applications.

  15. Coated woven materials and method of preparation

    DOEpatents

    McCreary, W.J.; Carroll, D.W.

    Coating of woven materials so that not only the outer surfaces are coated has been a problem. Now, a solution to that problem is by coating with materials, with metals or with pyrolytic carbon. Materials are deposited in Chemical Vapor Deposition (CND) reactions using a fluidized bed so that the porosity of the woven materials is retained and the tiny filaments which make up the strands which are woven (including inner as well as outer filaments) are substantially uniformly coated.

  16. Influence of wool and thermo-binder fibers relative fractions on the adhesion of non-woven Alfa fibers reinforced unsaturated polyester hybrid composites

    NASA Astrophysics Data System (ADS)

    Amin Omri, Med; Triki, A.; Ben Hassen, Med; Arous, M.; Bulou, A.

    2016-10-01

    Alfa/wool/thermo-binder fibers hybrid composites were investigated in order to analyze adhesion state. Bearing in mind the chemical structure of wool and thermo-binder fibers, this study revealed a good compatibility between the reinforcement and the matrix. Dielectric measurements revealed the presence of two dielectric relaxations in the composite. The first relaxation was attributed to the α mode relaxation and the second one was associated with the conductivity noted for high temperature. This study allowed the analysis of the interfacial polarization effect using the Havrilliak-Negami model in the electric modulus formalism. The lowness of this relaxation intensity revealed a good adhesion of the fibers in the matrix. Differential Scanning Calorimetry (DSC) showed a slow decrease of the Tg glass transition temperature compared to the matrix, which could be explained by the existence of interactions between the fibers and the matrix. Vibrational analysis, based on FTIR measurements, showed a less hydrophilic character of Alfa fibers owing to a basic dissociation that occurs between the wool fibers and the water molecules associated with Alfa fibers. Furthermore, adhesion mechanism in the composite material was established by covalent and hydrogen bonds. Tensile testing performed on this composite confirmed that such adhesion was improved by increasing the thermo-binder fibers relative fraction.

  17. 3D coral-like nitrogen-sulfur co-doped carbon-sulfur composite for high performance lithium-sulfur batteries

    PubMed Central

    Wu, Feng; Li, Jian; Tian, Yafen; Su, Yuefeng; Wang, Jing; Yang, Wen; Li, Ning; Chen, Shi; Bao, Liying

    2015-01-01

    3D coral-like, nitrogen and sulfur co-doped mesoporous carbon has been synthesized by a facile hydrothermal-nanocasting method to house sulfur for Li–S batteries. The primary doped species (pyridinic-N, pyrrolic-N, thiophenic-S and sulfonic-S) enable this carbon matrix to suppress the diffusion of polysulfides, while the interconnected mesoporous carbon network is favourable for rapid transport of both electrons and lithium ions. Based on the synergistic effect of N, S co-doping and the mesoporous conductive pathway, the as-fabricated C/S cathodes yield excellent cycling stability at a current rate of 4 C (1 C = 1675 mA g−1) with only 0.085% capacity decay per cycle for over 250 cycles and ultra-high rate capability (693 mAh g−1 at 10 C rate). These capabilities have rarely been reported before for Li-S batteries. PMID:26288961

  18. High hardness BaCb-(BxOy/BN) composites with 3D mesh-like fine grain-boundary structure by reactive spark plasma sintering.

    PubMed

    Vasylkiv, Oleg; Borodianska, Hanna; Badica, Petre; Grasso, Salvatore; Sakka, Yoshio; Tok, Alfred; Su, Liap Tat; Bosman, Michael; Ma, Jan

    2012-02-01

    Boron carbide B4C powders were subject to reactive spark plasma sintering (also known as field assisted sintering, pulsed current sintering or plasma assisted sintering) under nitrogen atmosphere. For an optimum hexagonal BN (h-BN) content estimated from X-ray diffraction measurements at approximately 0.4 wt%, the as-prepared BaCb-(BxOy/BN) ceramic shows values of Berkovich and Vickers hardness of 56.7 +/- 3.1 GPa and 39.3 +/- 7.6 GPa, respectively. These values are higher than for the vacuum SPS processed B4C pristine sample and the h-BN -mechanically-added samples. XRD and electronic microscopy data suggest that in the samples produced by reactive SPS in N2 atmosphere, and containing an estimated amount of 0.3-1.5% h-BN, the crystallite size of the boron carbide grains is decreasing with the increasing amount of N2, while for the newly formed lamellar h-BN the crystallite size is almost constant (approximately 30-50 nm). BN is located at the grain boundaries between the boron carbide grains and it is wrapped and intercalated by a thin layer of boron oxide. BxOy/BN forms a fine and continuous 3D mesh-like structure that is a possible reason for good mechanical properties.

  19. Conversion of uniform graphene oxide/polypyrrole composites into functionalized 3D carbon nanosheet frameworks with superior supercapacitive and sodium-ion storage properties

    NASA Astrophysics Data System (ADS)

    Wang, Huanwen; Zhang, Yu; Sun, Wenping; Tan, Hui Teng; Franklin, Joseph B.; Guo, Yuanyuan; Fan, Haosen; Ulaganathan, Mani; Wu, Xing-Long; Luo, Zhong-Zhen; Madhavi, Srinivasan; Yan, Qingyu

    2016-03-01

    Two-dimensional (2D) graphene oxide/polypyrrole (GO/PPy) hybrid materials derived from in-situ polymerization are used as precursors for constructing functionalized three-dimensional (3D) porous nitrogen-doped carbon nanosheet frameworks (FT-PNCNFs) through a one-step activation strategy. In the formation process of FT-PNCNFs, PPY is directly converted into hierarchical porous nitrogen-doped carbon layers, while GO is simultaneously reduced to become electrically conductive. The complementary functions of individual components endow the FT-PNCNFs with excellent properties for both supercapacitors (SCs) and sodium ion batteries (SIBs) applications. When tested in symmetrical SC, the FT-PNCNFs demonstrate superior energy storage behaviour. At an extremely high scan rate of 3000 mV s-1, the cyclic voltammetry (CV) curve retains an inspiring quasi-rectangle shape in KOH solution. Meanwhile, high capacitances (∼247 F g-1 at 10 mV s-1; ∼146 F g-1 at 3000 mV s-1) and good cycling stability (∼95% retention after 8000 cycles) are achieved. In addition, an attractive SIB anode performance could be achieved. The FT-PNCNFs electrode delivers a reversible capacity of 187 mAh g-1 during 160th cycle at 100 mA g-1. Its reversible capacity retains 144 mAh g-1 after extending the number of cycles to 500 at 500 mA g-1.

  20. 78 FR 50377 - Narrow Woven Ribbons With Woven Selvedge From Taiwan: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-19

    ...On May 21, 2013, the Department of Commerce (the Department) published the preliminary results of the second administrative review of the antidumping duty order on narrow woven ribbons with woven selvedge (narrow woven ribbons) from Taiwan. The period of review (POR) is September 1, 2011, through August 31, 2012. We received no comments from interested parties. Therefore, the final results do......

  1. Coated woven materials and method of preparation

    DOEpatents

    McCreary, William J.; Carroll, David W.

    1981-01-01

    Coating of woven materials so that not only the outer surfaces are coated has been a problem. Now, a solution to that problem is the following: Woven materials are coated with materials, for example with metals or with pyrolytic carbon, which materials are deposited in Chemical Vapor Deposition (CVD) reactions using a fluidized bed so that the porosity of the woven material is retained and so that the tiny filaments which make up the strands which are woven (including inner as well as outer filaments) are substantially uniformly coated.

  2. Fabrication and physical testing of graphite composite panels utilizing woven graphite fabric with current and advanced state-of-the-art resin systems

    NASA Technical Reports Server (NTRS)

    Lee, S. C. S.

    1979-01-01

    Three weaves were evaluated; a balanced plain weave, a balanced 8-harness satin weave, and a semiunidirectional crowfoot satin weave. The current state-of-the-art resin system selected was Fiberite's 934 Epoxy; the advanced resin systems evaluated were Phenolic, Phenolic/Novolac, Benzyl and Bismaleimide. The panels were fabricated for testing on NASA/Ames Research Center's Composites Modification Program. Room temperature mechanical tests only were performed by Hitco; the results are presented.

  3. Higher-order compositional modeling of three-phase flow in 3D fractured porous media based on cross-flow equilibrium

    NASA Astrophysics Data System (ADS)

    Moortgat, Joachim; Firoozabadi, Abbas

    2013-10-01

    Numerical simulation of multiphase compositional flow in fractured porous media, when all the species can transfer between the phases, is a real challenge. Despite the broad applications in hydrocarbon reservoir engineering and hydrology, a compositional numerical simulator for three-phase flow in fractured media has not appeared in the literature, to the best of our knowledge. In this work, we present a three-phase fully compositional simulator for fractured media, based on higher-order finite element methods. To achieve computational efficiency, we invoke the cross-flow equilibrium (CFE) concept between discrete fractures and a small neighborhood in the matrix blocks. We adopt the mixed hybrid finite element (MHFE) method to approximate convective Darcy fluxes and the pressure equation. This approach is the most natural choice for flow in fractured media. The mass balance equations are discretized by the discontinuous Galerkin (DG) method, which is perhaps the most efficient approach to capture physical discontinuities in phase properties at the matrix-fracture interfaces and at phase boundaries. In this work, we account for gravity and Fickian diffusion. The modeling of capillary effects is discussed in a separate paper. We present the mathematical framework, using the implicit-pressure-explicit-composition (IMPEC) scheme, which facilitates rigorous thermodynamic stability analyses and the computation of phase behavior effects to account for transfer of species between the phases. A deceptively simple CFL condition is implemented to improve numerical stability and accuracy. We provide six numerical examples at both small and larger scales and in two and three dimensions, to demonstrate powerful features of the formulation.

  4. Computational modeling and impact analysis of textile composite structures

    NASA Astrophysics Data System (ADS)

    Hur, Hae-Kyu

    This study is devoted to the development of an integrated numerical modeling enabling one to investigate the static and the dynamic behaviors and failures of 2-D textile composite as well as 3-D orthogonal woven composite structures weakened by cracks and subjected to static-, impact- and ballistic-type loads. As more complicated modeling about textile composite structures is introduced, some of homogenization schemes, geometrical modeling and crack propagations become more difficult problems to solve. To overcome these problems, this study presents effective mesh-generation schemes, homogenization modeling based on a repeating unit cell and sinusoidal functions, and also a cohesive element to study micro-crack shapes. This proposed research has two: (1) studying behavior of textile composites under static loads, (2) studying dynamic responses of these textile composite structures subjected to the transient/ballistic loading. In the first part, efficient homogenization schemes are suggested to show the influence of textile architectures on mechanical characteristics considering the micro modeling of repeating unit cell. Furthermore, the structures of multi-layered or multi-phase composites combined with different laminar such as a sub-laminate, are considered to find the mechanical characteristics. A simple progressive failure mechanism for the textile composites is also presented. In the second part, this study focuses on three main phenomena to solve the dynamic problems: micro-crack shapes, textile architectures and textile effective moduli. To obtain a good solutions of the dynamic problems, this research attempts to use four approaches: (I) determination of governing equations via a three-level hierarchy: micro-mechanical unit cell analysis, layer-wise analysis accounting for transverse strains and stresses, and structural analysis based on anisotropic plate layers, (II) development of an efficient computational approach enabling one to perform transient

  5. Towards functional 3D-stacked electrospun composite scaffolds of PHBV, silk fibroin and nanohydroxyapatite: Mechanical properties and surface osteogenic differentiation.

    PubMed

    Paşcu, Elena I; Cahill, Paul A; Stokes, Joseph; McGuinness, Garrett B

    2016-04-01

    Bone tissue engineering scaffolds have two challenging functional tasks to fulfil: to encourage cell proliferation, differentiation and matrix synthesis and to provide suitable mechanical stability upon implantation. Composites of biopolymers and bioceramics combine the advantages of both types of materials, resulting in better processability and enhanced mechanical and biological properties through matrix reinforcement. In the present study, novel thick bone composite scaffolds were successfully fabricated using electrospun flat sheets of polyhydroxybutyrate-polyhydroxyvalerate/nanohydroxyapatite/silk fibroin essence (2% nanohydroxyapatite - 2% silk fibroin essence and 5% nanohydroxyapatite - 5% silk fibroin essence, respectively). Their potential asin vitrobone regeneration scaffolds was evaluated using mouse calvarian osteoblast cells (MC3T3-E1), in terms of morphology (scanning electron microscope), cell attachment, cell proliferation, Col type I, osteopontin and bone alkaline phosphatase activity (Quantitative Real Time Polymerase Chain Reaction [qRT-PCR], enzyme-linked immunosorbent assay, immunocytochemistry). Electrospun polyhydroxybutyrate-polyhydroxyvalerate scaffolds were used as reference constructs. The results showed that the compressive and tensile mechanical properties of the scaffolds are dependent on the change in their composit