Science.gov

Sample records for copper-clad fr-4 laminates

  1. The effect of lead content and surface roughness on wetting and spreading of low-lead and no-lead solders on copper-clad FR-4 laminates

    SciTech Connect

    Stevenson, J.O.; Roberts, J.L.; Davidson, R.N.; Yost, F.G.; Hosking, F.M.

    1997-02-01

    Environmental and health concerns pertaining to lead have encouraged research into low-lead alloys for electronic soldering. The development of solder alloys containing lower amounts of lead than Sn/Pb eutectic (37 wt.% lead), but possessing similar properties, is an industry-wide goal. To determine the wettability of low-lead solders, 21 alloys each of Sn/Ag and Sn/Cu eutectic (containing 0 to 10 wt.% lead and/or indium) were tested on as-received copper-clad FR-4. Contact angles for the alloys ranged from 12.5 to 38.9{degrees} and area of spread measurements ranged from 5.2 to 17.3 mm{sup 2} compared with 5 to 150 and {approximately}19 mm{sup 2}, respectively, for Sn/Pb eutectic. Alloys with 8 to 10 wt.% lead showed contact angles and areas of spread similar to Sn/Pb eutectic under similar conditions. The best results on the as-received substrates, compared to the Sn/Pb eutectic, were obtained from the Sn/Ag eutectic with 10 wt.% lead. The very low-lead (less than 10 wt.% lead) and lead-free alloys, however, failed to achieve the performance level of eutectic Sn/Pb solders. A desire to improve the spreading of very low-lead and lead-free solders provided the impetus for these efforts to produce {open_quotes}engineered{close_quotes} rough surfaces. In an attempt to improve the wettability and spreading behavior of very low-lead and lead-free alloys, the very low-lead and lead-free members of the Sn/Ag system were tested on roughened copper-clad FR-4. Every alloy in the test suite demonstrated improvement in area of spread on the roughened substrates. The best results on the roughened substrates, compared to the Sn/Pb eutectic, were obtained from the Sn/Ag eutectic with 8 wt.% lead. The effects of surface roughness on the wettability and flow behavior of solder alloys has provided insight into surface morphologies that lead to improved solderability.

  2. Thermally Stable Siloxane Hybrid Matrix with Low Dielectric Loss for Copper-Clad Laminates for High-Frequency Applications.

    PubMed

    Kim, Yong Ho; Lim, Young-Woo; Kim, Yun Hyeok; Bae, Byeong-Soo

    2016-04-01

    We report vinyl-phenyl siloxane hybrid material (VPH) that can be used as a matrix for copper-clad laminates (CCLs) for high-frequency applications. The CCLs, with a VPH matrix fabricated via radical polymerization of resin blend consisting of sol-gel-derived linear vinyl oligosiloxane and bulky siloxane monomer, phenyltris(trimethylsiloxy)silane, achieve low dielectric constant (Dk) and dissipation factor (Df). The CCLs with the VPH matrix exhibit excellent dielectric performance (Dk = 2.75, Df = 0.0015 at 1 GHz) with stability in wide frequency range (1 MHz to 10 GHz) and at high temperature (up to 275 °C). Also, the VPH shows good flame resistance without any additives. These results suggest the potential of the VPH for use in high-speed IC boards. PMID:26982015

  3. A study of adhesion at the E-glass/FR4 interface

    SciTech Connect

    Kent, M.S.; Baca, P.; McNarama, W.F.; Jones, G.; Fein, D.; Wright, W.; Domeier, L.; Wu, W.L.; Wong, A.

    1995-11-01

    The majority of printed circuit boards are copper clad laminates composed of fiberglass cloth impregnated with FR4 epoxy. An important factor affecting the reliability of these assemblies is the integrity of the epoxy/glass fiber interface. The goal of this work is to investigate mechanisms for the loss of adhesive strength between E-glass and FR4 epoxy upon humidity and temperature conditioning. In this paper the authors discuss the distribution of moisture between the interface region and the bulk epoxy examined by neutron reflection, and the relationship of this data to adhesive strength.

  4. Interfacial microstructure and properties of copper clad steel produced using friction stir welding versus gas metal arc welding

    SciTech Connect

    Shen, Z.; Chen, Y.; Haghshenas, M.; Nguyen, T.; Galloway, J.; Gerlich, A.P.

    2015-06-15

    A preliminary study compares the feasibility and microstructures of pure copper claddings produced on a pressure vessel A516 Gr. 70 steel plate, using friction stir welding versus gas metal arc welding. A combination of optical and scanning electron microscopy is used to characterize the grain structures in both the copper cladding and heat affected zone in the steel near the fusion line. The friction stir welding technique produces copper cladding with a grain size of around 25 μm, and no evidence of liquid copper penetration into the steel. The gas metal arc welding of copper cladding exhibits grain sizes over 1 mm, and with surface microcracks as well as penetration of liquid copper up to 50 μm into the steel substrate. Transmission electron microscopy reveals that metallurgical bonding is produced in both processes. Increased diffusion of Mn and Si into the copper cladding occurs when using gas metal arc welding, although some nano-pores were detected in the FSW joint interface. - Highlights: • Cladding of steel with pure copper is possible using either FSW or GMAW. • The FSW yielded a finer grain structure in the copper, with no evidence of cracking. • The FSW joint contains some evidence of nano-pores at the interface of the steel/copper. • Copper cladding by GMAW contained surface cracks attributed to high thermal stresses. • The steel adjacent to the fusion line maintained a hardness value below 248 HV.

  5. Design of handwriting drawing board based on common copper clad laminate

    NASA Astrophysics Data System (ADS)

    Wang, Hongyuan; Gao, Wenzhi; Wang, Yuan

    2015-02-01

    Handwriting drawing board is not only a subject which can be used to write and draw, but also a method to measure and process weak signals. This design adopts 8051 single chip microprocessor as the main controller. It applies a constant-current source[1][2] to copper plate and collects the voltage value according to the resistance divider effect. Then it amplifies the signal with low-noise and high-precision amplifier[3] AD620 which is placed in the low impedance and anti-interference pen. It converts analog signal to digital signal by an 11-channel, 12-bit A/D converter TLC2543. Adoption of average filtering algorithm can effectively improve the measuring accuracy, reduce the error and make the collected voltage signal more stable. The accurate position can be detected by scanning the horizontal and vertical ordinates with the analog switch via the internal bridge of module L298 which can change the direction of X-Y axis signal scan. DM12864 is used as man-machine interface and this hominization design is convenient for man-machine communication. This collecting system has high accuracy, high stability and strong anti-interference capability. It's easy to control and has very large development space in the future.

  6. Initial corrosion behavior of a copper-clad plate in typical outdoor atmospheric environments

    NASA Astrophysics Data System (ADS)

    Yi, Pan; Xiao, Kui; Ding, Kangkang; Yan, Lidan; Dong, Chaofang; Li, Xiaogang

    2016-01-01

    A copper-clad printed circuit board (PCB-Cu) was subjected to long-term exposure test under typical Chinese atmospheric environments to study corrosion failure mechanisms. The corrosion behavior was investigated by analyzing electrochemical impedance, scanning Kelvin probes, stereo and scanning electron microscopes, and energy-dispersive spectra. Results showed that the initial surface potential was unevenly distributed. The outdoor PCB-Cu samples suffered severe corrosion caused by dust particles, contaminated media, and microorganisms after long-term atmospheric exposure. The initial localized corrosion was exacerbated and progressed to general corrosion for samples in Turpan, Beijing, and Wuhan under prolonged exposure, whereas PCB-Cu in Xishuangbanna was only slightly corroded. The tendency for electrochemical migration (ECM) of PCB-Cu was relatively low when applied with a bias voltage of 12 V. ECM was only observed in the PCB-Cu samples in Beijing. Contaminated medium and high humidity synergistically affected ECM corrosion in PCB-Cu materials. [Figure not available: see fulltext.

  7. Numerical simulation of temperature field in horizontal core-filling continuous casting for copper cladding aluminum rods

    NASA Astrophysics Data System (ADS)

    Su, Ya-jun; Liu, Xin-hua; Wu, Yong-fu; Huang, Hai-you; Xie, Jian-xin

    2013-07-01

    The steady-state temperature field of horizontal core-filling continuous casting (HCFC) for producing copper cladding aluminum rods was simulated by finite element method to investigate the effects of key processing parameters on the positions of solid-liquid interfaces (SLIs) of copper and aluminum. It is found that mandrel tube length and mean withdrawing speed have significant effects on the SLI positions of both copper and aluminum. Aluminum casting temperature ( T Al) (1003-1123 K) and secondary cooling water flux (600-900 L·h-1) have little effect on the SLI of copper but cause the SLI of aluminum to move 2-4 mm. When T Al is in a range of 1043-1123 K, the liquid aluminum can fill continuously into the pre-solidified copper tube. Based on the numerical simulation, reasonable processing parameters were determined.

  8. Effects of Processing Parameters on the Fabrication of Copper Cladding Aluminum Rods by Horizontal Core-Filling Continuous Casting

    NASA Astrophysics Data System (ADS)

    Su, Ya-Jun; Liu, Xin-Hua; Huang, Hai-You; Wu, Chun-Jing; Liu, Xue-Feng; Xie, Jian-Xin

    2011-02-01

    Copper cladding aluminum (CCA) rods with a diameter of 30 mm and a sheath thickness of 3 mm were fabricated by horizontal core-filling continuous casting (HCFC) technology. The effects of key processing parameters, such as the length of the mandrel tube of composite mold, aluminum casting temperature, flux of the secondary cooling water, and mean withdrawing speed were optimized based on some quality criteria, including the uniformity of the sheath thickness, integrality of the rods, and thickness of the interface. The causes of internal flaws formation of CCA rods were also discussed. The results showed that the continuity of the liquid aluminum core-filling process and the interface reaction control between solid copper and liquid aluminum were two key problems that strongly affected the stability of the casting process and the product quality. Our research indicated that for the CCA rod with the previously mentioned size, the optimal length of mandrel tube was 210 mm. A shorter mandrel tube allowed of easier erosion at the interface, which led to a nonuniform sheath thickness. Conversely, it tended to result in a discontinuous filling process of liquid aluminum, which causes shrinkage or cold shuts. The optimal casting temperatures of copper and aluminum were 1503 K (1230 °C) and 1043 K to 1123 K (770 °C to 850 °C), respectively. When the casting temperature of aluminum was below 1043 K (770 °C), the casting process would be discontinuous, resulting in shrinkages or cold shuts. Nevertheless, when the casting temperature of aluminum was higher than 1123 K (850 °C), a severe interface reaction between solid copper and liquid aluminum would occur. The proper flux of the secondary cooling water and the mean withdrawing speed were determined as 600 to 800 L/h and 60 to 87 mm/min, respectively. In the previously mentioned proper ranges of processing parameters, the interfacial shear strengths of CCA rods were 40.5 to 67.9 MPa.

  9. Interfacial Microstructure and Bonding Strength of Copper Cladding Aluminum Rods Fabricated by Horizontal Core-Filling Continuous Casting

    NASA Astrophysics Data System (ADS)

    Su, Ya-Jun; Liu, Xin-Hua; Huang, Hai-You; Liu, Xue-Feng; Xie, Jian-Xin

    2011-12-01

    Copper cladding aluminum (CCA) rods with a diameter of 30 mm and a sheath thickness of 3 mm were fabricated by horizontal core-filling continuous casting (HCFC) technology. The microstructure and morphology, distribution of chemical components, and phase composition of the interface between Cu and Al were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), and energy dispersive spectrometer (EDS). The formation mechanism of the interface and the effects of key processing parameters, e.g., aluminum casting temperature, secondary cooling intensity, and mean withdrawing speed on the interfacial microstructure and bonding strength were investigated. The results show that the CCA rod has a multilayered interface, which is composed of three sublayers—sublayer I is Cu9Al4 layer, sublayer II is CuAl2 layer, and sublayer III is composed of α-Al/CuAl2 pseudo eutectic. The thickness of sublayer III, which occupies 92 to 99 pct of the total thickness of the interface, is much larger than the thicknesses of sublayers I and II. However, the interfacial bonding strength is dominated by the thicknesses of sublayers I and II; i.e., the bonding strength decreases with the rise of the thicknesses of sublayers I and II. When raising the aluminum casting temperature, the total thickness of the interface increases while the thicknesses of sublayers I and II decrease and the bonding strength increases. Either augmenting the secondary cooling intensity or increasing the mean withdrawing speed results in the decrease in both total thickness of the interface and the thicknesses of sublayers I and II, and an increase in the interfacial bonding strength. The CCA rod with the largest interfacial bonding strength of 67.9 ± 0.5 MPa was fabricated under such processing parameters as copper casting temperature 1503 K (1230 °C), aluminum casting temperature 1063 K (790 °C), primary cooling water flux 600 L/h, secondary cooling water flux 700 L/h, and

  10. Invertebrate lamins

    SciTech Connect

    Melcer, Shai; Gruenbaum, Yosef . E-mail: gru@vms.huji.ac.il; Krohne, Georg . E-mail: krohne@biozentrum.uni-wuerzburg.de

    2007-06-10

    Lamins are the main component of the nuclear lamina and considered to be the ancestors of all intermediate filament proteins. They are localized mainly at the nuclear periphery where they form protein complexes with integral proteins of the nuclear inner membrane, transcriptional regulators, histones and chromatin modifiers. Studying lamins in invertebrate species has unique advantages including the smaller number of lamin genes in the invertebrate genomes and powerful genetic analyses in Caenorhabditis elegans and Drosophila melanogaster. These simpler nuclear lamina systems allow direct analyses of their structure and functions. Here we give an overview of recent advances in the field of invertebrate nuclear lamins with special emphasis on their evolution, assembly and functions.

  11. Photoresist laminate

    DOEpatents

    Andrade, A.D.; Galbraith, L.K.

    1979-10-01

    The disclosure relates to a laminated negative dry-film photoresist for the production of thick, as well as thin, patterns with vertical sidewalls. Uniform depthwise exposure in a photoresist layer is effected by the use of an ultraviolet filtering top layer.

  12. Laminate article

    DOEpatents

    Williams, Robert K.; Paranthaman, Mariappan; Chirayil, Thomas G.; Lee, Dominic F.; Goyal, Amit; Feenstra, Roeland

    2002-01-01

    A laminate article comprises a substrate and a biaxially textured (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer over the substrate, wherein 0laminate article can include a layer of YBCO over the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. A layer of CeO.sub.2 between the YBCO layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer can also be include. Further included can be a layer of YSZ between the CeO.sub.2 layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. The substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  13. Hybrid composite laminate structures

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Lark, R. F. (Inventor)

    1977-01-01

    An invention which relates to laminate structures and specifically to essentially anisotropic fiber composite laminates is described. Metal foils are selectively disposed within the laminate to produce increased resistance to high velocity impact, fracture, surface erosion, and other stresses within the laminate.

  14. Lamins as cancer biomarkers.

    PubMed

    Foster, Clare R; Przyborski, Stefan A; Wilson, Robert G; Hutchison, Christopher J

    2010-02-01

    Lamins are multifunctional proteins that are often aberrantly expressed or localized in tumours. Here, we endeavour to assess their uses as cancer biomarkers: to diagnose tumours, analyse cancer characteristics and predict patient survival. It appears that the nature of lamin function in cancer is very complex. Lamin expression can be variable between and even within cancer subtypes, which limits their uses as diagnostic biomarkers. Expression of A-type lamins is a marker of differentiated tumour cells and has been shown to be a marker of good or poor patient survival depending on tumour subtype. Further research into the functions of lamins in cancer cells and the mechanisms that determine its patterns of expression may provide more potential uses of lamins as cancer biomarkers. PMID:20074078

  15. Honeycomb-laminate composite structure

    NASA Technical Reports Server (NTRS)

    Gilwee, W. J., Jr.; Parker, J. A. (Inventor)

    1977-01-01

    A honeycomb-laminate composite structure was comprised of: (1) a cellular core of a polyquinoxaline foam in a honeycomb structure, and (2) a layer of a noncombustible fibrous material impregnated with a polyimide resin laminated on the cellular core. A process for producing the honeycomb-laminate composite structure and articles containing the honeycomb-laminate composite structure is described.

  16. Laminate armor and related methods

    SciTech Connect

    Chu, Henry S; Lillo, Thomas M; Zagula, Thomas M

    2013-02-26

    Laminate armor and methods of manufacturing laminate armor. Specifically, laminate armor plates comprising a commercially pure titanium layer and a titanium alloy layer bonded to the commercially pure titanium outer layer are disclosed, wherein an average thickness of the titanium alloy inner layer is about four times an average thickness of the commercially pure titanium outer layer. In use, the titanium alloy layer is positioned facing an area to be protected. Additionally, roll-bonding methods for manufacturing laminate armor plates are disclosed.

  17. Laminated BEAM loops

    NASA Astrophysics Data System (ADS)

    Danisch, Lee A.

    1996-10-01

    BEAM sensors include treated loops of optical fiber that modulate optical throughput with great sensitivity and linearity, in response to curvature of the loop out of its plane. This paper describes BEAM sensors that have two loops treated in opposed fashion, hermetically sealed in flexible laminations. The sensors include an integrated optoelectronics package that extracts curvature information from the treated portion of the loops while rejecting common mode errors. The laminated structure is used to sense various parameters including displacement, force, pressure, flow, and acceleration.

  18. 78 FR 19007 - Certain Products Having Laminated Packaging, Laminated Packaging, and Components Thereof...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-28

    ... COMMISSION Certain Products Having Laminated Packaging, Laminated Packaging, and Components Thereof.... 1337, on behalf of Lamina Packaging Innovations LLC of Longview, Texas. An amended complaint was filed... importation of certain products having laminated packaging, laminated packaging, and components thereof...

  19. 78 FR 13083 - Products Having Laminated Packaging, Laminated Packaging, and Components Thereof; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-26

    ... COMMISSION Products Having Laminated Packaging, Laminated Packaging, and Components Thereof; Notice of... Commission has received a complaint entitled Products Having Laminated ] Packaging, Laminated Packaging, and... filed on behalf of Lamina Packaging Innovations LLC on February 20, 2013. The complaint...

  20. Laminated piezoelectric transformer

    NASA Technical Reports Server (NTRS)

    Vazquez Carazo, Alfredo (Inventor)

    2006-01-01

    A laminated piezoelectric transformer is provided using the longitudinal vibration modes for step-up voltage conversion applications. The input portions are polarized to deform in a longitudinal plane and are bonded to an output portion. The deformation of the input portions is mechanically coupled to the output portion, which deforms in the same longitudinal direction relative to the input portion. The output portion is polarized in the thickness direction relative its electrodes, and piezoelectrically generates a stepped-up output voltage.

  1. Thermally stable laminating resins

    NASA Technical Reports Server (NTRS)

    Jones, R. J.; Vaughan, R. W.; Burns, E. A.

    1972-01-01

    Improved thermally stable laminating resins were developed based on the addition-type pyrolytic polymerization. Detailed monomer and polymer synthesis and characterization studies identified formulations which facilitate press molding processing and autoclave fabrication of glass and graphite fiber reinforced composites. A specific resin formulation, termed P10P was utilized to prepare a Courtaulds HMS reinforced simulated airfoil demonstration part by an autoclave molding process.

  2. An overview of laminate materials with enhanced dielectric properties

    NASA Astrophysics Data System (ADS)

    Mumby, Stephen J.

    1989-03-01

    This report focuses on laminate materials (resins and reinforcements) having potential applications in the manufacture of multi-layer printed wiring boards (PWBs) that are required to efficiently transmit high-speed digital pulses. It is intended to be a primer and a reference for selection of candidate materials for such high-performance PWBs. Included are dielectric and physical properties, and where available chemical composition and/or structure, commercial availability, compatibility with typical PWB processing schemes and approximate relative cost. Recommendations are made as to the most viable candidate materials for this type of PWB application, based on a comparison of electrical and physical properties together with processing and cost considerations. The cyanate ester resin system appears promising. Such a resin may be reinforced with regular E-glass, or the more newly available S-glass, to produce a laminate useful for intermediate performance applications. For more demanding applications the E-glass will have to be replaced by a material of much lower relative permittivity. The expanded-PTFE reinforced laminates from W. L. Gore appear to be a good choice for these applications. The processing of the Gore materials can be expected to deviate from that used with FR-4 type materials, but is likely to be less problematic than laminates comprised of a fluorinated resin. Processing is a key obstacle to the implementation of any of the new materials herein. If implementation is to be successful, programs must be established to develop and optimize processing procedures. Cost will remain an important issue. However, the higher cost of the new materials may be justified in high-end products by the performance they deliver.

  3. Symmetric Composite Laminate Stress Analysis

    NASA Technical Reports Server (NTRS)

    Wang, T.; Smolinski, K. F.; Gellin, S.

    1985-01-01

    It is demonstrated that COSMIC/NASTRAN may be used to analyze plate and shell structures made of symmetric composite laminates. Although general composite laminates cannot be analyzed using NASTRAN, the theoretical development presented herein indicates that the integrated constitutive laws of a symmetric composite laminate resemble those of a homogeneous anisotropic plate, which can be analyzed using NASTRAN. A detailed analysis procedure is presented, as well as an illustrative example.

  4. Solar cell module lamination process

    DOEpatents

    Carey, Paul G.; Thompson, Jesse B.; Aceves, Randy C.

    2002-01-01

    A solar cell module lamination process using fluoropolymers to provide protection from adverse environmental conditions and thus enable more extended use of solar cells, particularly in space applications. A laminate of fluoropolymer material provides a hermetically sealed solar cell module structure that is flexible and very durable. The laminate is virtually chemically inert, highly transmissive in the visible spectrum, dimensionally stable at temperatures up to about 200.degree. C. highly abrasion resistant, and exhibits very little ultra-violet degradation.

  5. Beach lamination: Nature and origin

    USGS Publications Warehouse

    Clifton, H.E.

    1969-01-01

    A distinctive two-fold sedimentation unit characterizes lamination in the upper swash zone of beaches. Within the unit a fine and/or a heavy mineral rich layer at the base grades upward into a coarser and/or a heavy mineral poor layer at the top. This distinctive type of lamination results from grain segregation within bed flow during wave backwash. ?? 1969.

  6. Holographic nondestructive testing of laminates

    NASA Technical Reports Server (NTRS)

    Stuckenberg, F. H.

    1973-01-01

    Very small differences in laminate thickness result in interference fringes in holograph image. These indicate presence of unbonded area. Theoretical knowledge of membrane deflection may be used in conjunction with reduced number of pretest experiments to determine number of optical fringes that should appear for given laminate.

  7. Self-Healing Laminate System

    NASA Technical Reports Server (NTRS)

    Beiermann, Brett A. (Inventor); Keller, Michael W. (Inventor); White, Scott R. (Inventor); Sottos, Nancy R. (Inventor)

    2016-01-01

    A laminate material may include a first flexible layer, and a self-healing composite layer in contact with the first flexible layer. The composite layer includes an elastomer matrix, a plurality of first capsules including a polymerizer, and a corresponding activator for the polymerizer. The laminate material may self-heal when subjected to a puncture or a tear.

  8. Lamin B receptor

    PubMed Central

    Olins, Ada L; Rhodes, Gale; Welch, David B Mark; Zwerger, Monika

    2010-01-01

    Lamin B receptor (LBR) is an integral membrane protein of the interphase nuclear envelope (NE). The N-terminal end resides in the nucleoplasm, binding to lamin B and heterochromatin, with the interactions disrupted during mitosis. The C-terminal end resides within the inner nuclear membrane, retreating with the ER away from condensing chromosomes during mitotic NE breakdown. Some of these properties are interpretable in terms of our current structural knowledge of LBR, but many of the structural features remain unknown. LBR apparently has an evolutionary history which brought together at least two ancient conserved structural domains (i.e., Tudor and sterol reductase). This convergence may have occurred with the emergence of the chordates and echinoderms. It is not clear what survival values have maintained LBR structure during evolution. But it seems likely that roles in post-mitotic nuclear reformation, interphase NE growth and compartmentalization of nuclear architecture might have provided some evolutionary advantage to preservation of the LBR gene. PMID:21327105

  9. Vacuum lamination of photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Burger, D. R.

    1982-01-01

    Vacuum lamination of terrestrial photovoltaic modules is a new high volume process requiring new equipment and newly develop materials. Equipment development, materials research, and some research in related fields and testing methods are discussed.

  10. Internal Stresses in Laminated Construction

    NASA Technical Reports Server (NTRS)

    Heim, A L; Knauss, A C; Seutter, Louis

    1923-01-01

    This report reviews the procedure employed in an investigation of the sources and influence of internal stresses in laminated construction, and discusses the influence of shrinkage and swelling stresses caused by atmospheric conditions upon the tensile strength across grain in laminated construction with special reference to airplane propellers. The investigation covered three sources of internal stress, namely, the combination of plain-sawed and quarter-sawed material in the same construction, the gluing together of laminations of different moisture contents, and the gluing together of laminations of different densities. Glued specimens and free specimens, made up under various manufacturing conditions, were subjected to various climatic changes inducing internal stresses and then were tested.

  11. Laminated electromagnetic pump stator core

    DOEpatents

    Fanning, A.W.

    1995-08-08

    A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference. This pump is used in nuclear fission reactors. 19 figs.

  12. Laminated electromagnetic pump stator core

    DOEpatents

    Fanning, Alan W.

    1995-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference.

  13. Interphase phosphorylation of lamin A.

    PubMed

    Kochin, Vitaly; Shimi, Takeshi; Torvaldson, Elin; Adam, Stephen A; Goldman, Anne; Pack, Chan-Gi; Melo-Cardenas, Johanna; Imanishi, Susumu Y; Goldman, Robert D; Eriksson, John E

    2014-06-15

    Nuclear lamins form the major structural elements that comprise the nuclear lamina. Loss of nuclear structural integrity has been implicated as a key factor in the lamin A/C gene mutations that cause laminopathies, whereas the normal regulation of lamin A assembly and organization in interphase cells is still undefined. We assumed phosphorylation to be a major determinant, identifying 20 prime interphase phosphorylation sites, of which eight were high-turnover sites. We examined the roles of these latter sites by site-directed mutagenesis, followed by detailed microscopic analysis - including fluorescence recovery after photobleaching, fluorescence correlation spectroscopy and nuclear extraction techniques. The results reveal three phosphorylation regions, each with dominant sites, together controlling lamin A structure and dynamics. Interestingly, two of these interphase sites are hyper-phosphorylated in mitotic cells and one of these sites is within the sequence that is missing in progerin of the Hutchinson-Gilford progeria syndrome. We present a model where different phosphorylation combinations yield markedly different effects on the assembly, subunit turnover and the mobility of lamin A between, and within, the lamina, the nucleoplasm and the cytoplasm of interphase cells. PMID:24741066

  14. Lamin A, farnesylation and aging.

    PubMed

    Reddy, Sita; Comai, Lucio

    2012-01-01

    Lamin A is a component of the nuclear envelope that is synthesized as a precursor prelamin A molecule and then processed into mature lamin A through sequential steps of posttranslational modifications and proteolytic cleavages. Remarkably, over 400 distinct point mutations have been so far identified throughout the LMNA gene, which result in the development of at least ten distinct human disorders, collectively known as laminopathies, among which is the premature aging disease Hutchinson-Gilford progeria syndrome (HGPS). The majority of HGPS cases are associated with a single point mutation in the LMNA gene that causes the production of a permanently farnesylated mutant lamin A protein termed progerin. The mechanism by which progerin leads to premature aging and the classical HGPS disease phenotype as well as the relationship between this disorder and the onset of analogous symptoms during the lifespan of a normal individual are not well understood. Yet, recent studies have provided critical insights on the cellular processes that are affected by accumulation of progerin and have suggested that cellular alterations in the lamin A processing pathway leading to the accumulation of farnesylated prelamin A intermediates may play a role in the aging process in the general population. In this review we provide a short background on lamin A and its maturation pathway and discuss the current knowledge of how progerin or alterations in the prelamin A processing pathway are thought to influence cell function and contribute to human aging. PMID:21871450

  15. Lamin A, farnesylation and aging

    SciTech Connect

    Reddy, Sita; Comai, Lucio

    2012-01-01

    Lamin A is a component of the nuclear envelope that is synthesized as a precursor prelamin A molecule and then processed into mature lamin A through sequential steps of posttranslational modifications and proteolytic cleavages. Remarkably, over 400 distinct point mutations have been so far identified throughout the LMNA gene, which result in the development of at least ten distinct human disorders, collectively known as laminopathies, among which is the premature aging disease Hutchinson-Gilford progeria syndrome (HGPS). The majority of HGPS cases are associated with a single point mutation in the LMNA gene that causes the production of a permanently farnesylated mutant lamin A protein termed progerin. The mechanism by which progerin leads to premature aging and the classical HGPS disease phenotype as well as the relationship between this disorder and the onset of analogous symptoms during the lifespan of a normal individual are not well understood. Yet, recent studies have provided critical insights on the cellular processes that are affected by accumulation of progerin and have suggested that cellular alterations in the lamin A processing pathway leading to the accumulation of farnesylated prelamin A intermediates may play a role in the aging process in the general population. In this review we provide a short background on lamin A and its maturation pathway and discuss the current knowledge of how progerin or alterations in the prelamin A processing pathway are thought to influence cell function and contribute to human aging.

  16. Thermoelastic analysis of laminated plates. I - Symmetric specially orthotropic laminates

    SciTech Connect

    Wu, C.H.; Tauchert, T.R.

    1980-04-01

    Thermally induced deformations and stress resultants in symmetric laminated plates are analyzed. The method of M. Levy is used to study the transverse bending of a specially orthotropic laminate having two simply supported edges and subject to a temperature distribution that does not vary in a direction parallel to the simple supports. A solution is also obtained for the problem of in-plane stretching of the plate middle surface caused by a general three-dimensional temperature field. As an illustrative example, the thermoelastic response of a unidirectionally fiber-reinforced plate to a temperature variation that is linear in the thickness direction is computed.

  17. Both lamin A and lamin C mutations cause lamina instability as well as loss of internal nuclear lamin organization

    SciTech Connect

    Broers, Jos L.V. . E-mail: jos.broers@molcelb.unimaas.nl; Kuijpers, H.J.H.; Oestlund, C.; Worman, H.J.; Endert, J.; Ramaekers, F.C.S.

    2005-04-01

    We have applied the fluorescence loss of intensity after photobleaching (FLIP) technique to study the molecular dynamics and organization of nuclear lamin proteins in cell lines stably transfected with green fluorescent protein (GFP)-tagged A-type lamin cDNA. Normal lamin A and C proteins show abundant decoration of the inner layer of the nuclear membrane, the nuclear lamina, and a generally diffuse localization in the nuclear interior. Bleaching studies revealed that, while the GFP-tagged lamins in the lamina were virtually immobile, the intranuclear fraction of these molecules was partially mobile. Intranuclear lamin C was significantly more mobile than intranuclear lamina A. In search of a structural cause for the variety of inherited diseases caused by A-type lamin mutations, we have studied the molecular organization of GFP-tagged lamin A and lamin C mutants R453W and R386K, found in Emery-Dreifuss muscular dystrophy (EDMD), and lamin A and lamin C mutant R482W, found in patients with Dunnigan-type familial partial lipodystrophy (FPLD). In all mutants, a prominent increase in lamin mobility was observed, indicating loss of structural stability of lamin polymers, both at the perinuclear lamina and in the intranuclear lamin organization. While the lamin rod domain mutant showed overall increased mobility, the tail domain mutants showed mainly intranuclear destabilization, possibly as a result of loss of interaction with chromatin. Decreased stability of lamin mutant polymers was confirmed by flow cytometric analyses and immunoblotting of nuclear extracts. Our findings suggest a loss of function of A-type lamin mutant proteins in the organization of intranuclear chromatin and predict the loss of gene regulatory function in laminopathies.

  18. FR4-based electromagnetic energy harvester for wireless sensor nodes

    NASA Astrophysics Data System (ADS)

    Hatipoglu, G.; Ürey, H.

    2010-01-01

    Electromagnetic (EM) energy harvesting seems to be one of the most promising ways to power wireless sensors in a wireless sensor network. In this paper, FR4, the most commonly used PCB material, is utilized as a mechanical vibrating structure for EM energy harvesting for body-worn sensors and intelligent tire sensors, which involve impact loadings. FR4 can be a better material for such applications compared to silicon MEMS devices due to lower stiffness and broadband response. In order to demonstrate FR4 performance and broadband response, three moving magnet type EM generator designs are developed and investigated throughout the paper. A velocity-damped harvester simulation model is first developed, including a detailed magnetic model and the magnetic damping effects. The numerical results agree well with the experimental results. Human running acceleration at the hip area that is obtained experimentally is simulated in order to demonstrate system performance, which results in a scavenged power of about 40 µW with 15 m s-2 acceleration input. The designed FR4 energy scavengers with mechanical stoppers implemented are particularly well suited for nearly periodic and non-sinusoidal high- g excitations with rich harmonic content. For the intelligent tire applications, a special compact FR4 scavenger is designed that is able to withstand large shocks and vibrations due to mechanical shock stoppers built into the structure. Using our design, 0.4 mW power across a load resistance at off-resonance operation is obtained in shaker experiments. In the actual operation, the tangential accelerations as a result of the tire-road contact are estimated to supply power around 1 mW with our design, which is sufficient for powering wireless tire sensors. The normalized power density (NPD) of the designed actuators compares favorably with most actuators reported in the literature.

  19. Impedances of Laminated Vacuum Chambers

    SciTech Connect

    Burov, A.; Lebedev, V.; /Fermilab

    2011-06-22

    First publications on impedance of laminated vacuum chambers are related to early 70s: those are of S. C. Snowdon [1] and of A. G. Ruggiero [2]; fifteen years later, a revision paper of R. Gluckstern appeared [3]. All the publications were presented as Fermilab preprints, and there is no surprise in that: the Fermilab Booster has its laminated magnets open to the beam. Being in a reasonable mutual agreement, these publications were all devoted to the longitudinal impedance of round vacuum chambers. The transverse impedance and the flat geometry case were addressed in more recent paper of K. Y. Ng [4]. The latest calculations of A. Macridin et al. [5] revealed some disagreement with Ref. [4]; this fact stimulated us to get our own results on that matter. Longitudinal and transverse impendances are derived for round and flat laminated vacuum chambers. Results of this paper agree with Ref. [5].

  20. Lamin-Binding Proteins in Caenorhabditis elegans.

    PubMed

    Dobrzynska, Agnieszka; Askjaer, Peter; Gruenbaum, Yosef

    2016-01-01

    The nuclear lamina, composed of lamins and numerous lamin-associated proteins, is required for mechanical stability, mechanosensing, chromatin organization, developmental gene regulation, mRNA transcription, DNA replication, nuclear assembly, and nuclear positioning. Mutations in lamins or lamin-binding proteins cause at least 18 distinct human diseases that affect specific tissues such as muscle, adipose, bone, nerve, or skin, and range from muscular dystrophies to lipodystrophy, peripheral neuropathy, or accelerated aging. Caenorhabditis elegans has unique advantages in studying lamin-binding proteins. These advantages include the low complexity of genes encoding lamin and lamin-binding proteins, advanced transgenic techniques, simple application of RNA interference, sophisticated genetic strategies, and a large collection of mutant lines. This chapter provides detailed and comprehensive protocols for the genetic and phenotypic analysis of lamin-binding proteins in C. elegans. PMID:26778571

  1. Basic mechanics of laminated composite plates

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.

    1994-01-01

    The mechanics of laminated composite materials is presented in a clear manner with only essential derivations included. The constitutive equations in all of their forms are developed and then summarized in a separate section. The effects of hygrothermal effects are included. The prediction of the engineering constants for a laminate are derived. Strength of laminated composites is not covered.

  2. PCB glass-fibre laminates: Thermal conductivity measurements and their effect on simulation

    NASA Astrophysics Data System (ADS)

    Sarvar, F.; Poole, N. J.; Witting, P. A.

    1990-12-01

    Accurate values of thermal conductivity are required for the simulation of temperature phenomena in electronic circuits. This paper presents the results of measurements carried out to determine the thermal conductivity along and normal to the plane of fibre glass laminates used in the manufacture of printed circuit boards. It has been found that the reinforced fibre-glass substrates used in PCBs are strongly anisotropic with the conductivity normal to the boards being much smaller than tangential to it. The test samples were type FR4 epoxy/glass laminates. An experiment has been designed which determines the thermal conductivity in-the-plane of the laminates by matching the measured temperature distribution along a heated specimen with a finite difference solution. An electrically heated Lees’ disc apparatus is also used to measure the thermal conductivity of these boards in a direction normal to their plane. The samples tested yielded values of 0.343 W/mK and 1.059 W/mK for thermal conductivity through and along the plane of the boards, respectively.

  3. Multilayer printed wiring board lamination

    SciTech Connect

    Lula, J.W.

    1980-06-01

    The relationship of delamination resistance of multilayer PWBs made from GF material to manufacturing process variables was investigated. A unique quantitative test method developed during this project shows that delamination resistance is highly sensitive to material conditioning, to innerlayer surface treatment, and to post-lamination storage conditions, but is relatively insensitive to cure cycle variations.

  4. Steady state response of unsymmetrically laminated plates

    SciTech Connect

    Hosokawa, Kenji; Kawashima, Katsuya; Sakata, Toshiyuki

    1995-11-01

    A numerical approach for analyzing the forced vibration problem of a symmetrically laminated FRP (fiber reinforced plastic) composite plate was proposed by the authors. In the present paper, this approach is modified for application to an unsymmetrically laminated FRP composite plate. Numerical calculations are carried out for the clamped antisymmetrically laminated rectangular and elliptical plates which are a kind of unsymmetrically laminated plate. Then,, the effects of the lamina material and the fiber orientation angle on the steady state response are discussed. Furthermore, it is investigated that what structural damping factor is most influenced on the steady state response of an antisymmetrically laminated plate.

  5. Vacuum multilayer lamination of printed wiring boards

    NASA Astrophysics Data System (ADS)

    Wilkus, J. W.

    1992-11-01

    This experiment investigates vacuum multilayer lamination of rigid/flex, epoxy glass, polyimide glass, and polyimide quartz printed wiring boards. The effectiveness of the vacuum in removing entrapped air during the lamination cycle is demonstrated. The results of the experiment have also shown that vacuum lamination of epoxy glass multilayers improves the delamination resistance. Thus, epoxy glass multilayers that have been vacuum laminated will be able to withstand soldering temperatures longer without delaminating. Also, the experiment shows that vacuum multilayer lamination does not significantly change thickness, layer-to-layer registration, glass transition temperature, dielectric spacing between conductors, electrical resistance following thermal shock test, and other critical printed wiring board properties.

  6. Microstress prediction in composite laminate

    NASA Astrophysics Data System (ADS)

    Hutapea, Parsaoran

    2000-10-01

    The objective of this research is to develop a macroscopic theory, which can provide the connection between macromechanics and micromechanics in characterizing the micro-stress of composite laminates near edges and holes. The micropolar theory, a class of higher-order elasticity theory, of composite laminate mechanics is implemented in a well-known Pipes-Pagano free edge boundary problem. The micropolar homogenization method to determine the micropolar anisotropic effective elastic moduli is presented. A displacement-based finite element method based on micropolar theory in anisotropic solids is developed in analyzing composite laminates. The effects of fiber volume fraction and cell size on the normal stress along the artificial interface of the composite laminate are also investigated. The stress response based on micropolar theory is compared with those deduced from the micromechanics and classical elasticity theory. Special attention of the investigation focuses on the stress fields near the free edge where the high macrostress gradient occurs. The normal stresses along the artificial interface and especially, the microstress along the fiber/matrix interface on the critical cell near the free edge where the high macrostress gradient detected are the focus of this investigation. These microstresses are expected to dominate the failure initiation process in composite laminate. The implementation of micropolar analysis on the prediction of microstress of the critical cell near the free edge is found to be in very good agreement with "exact" microstress solutions. It is demonstrated that the micropolar theory is able to capture the microstress correctly from the homogenized solutions.

  7. Lamin in inflammation and aging.

    PubMed

    Tran, Joseph R; Chen, Haiyang; Zheng, Xiaobin; Zheng, Yixian

    2016-06-01

    Aging is characterized by a progressive loss of tissue function and an increased susceptibility to injury and disease. Many age-associated pathologies manifest an inflammatory component, and this has led to the speculation that aging is at least in part caused by some form of inflammation. However, whether or not inflammation is truly a cause of aging, or is a consequence of the aging process is unknown. Recent work using Drosophila has uncovered a mechanism where the progressive loss of lamin-B in the fat body upon aging triggers systemic inflammation. This inflammatory response perturbs the local immune response of the neighboring gut tissue and leads to hyperplasia. Here, we will discuss the literature connecting lamins to aging and inflammation. PMID:27023494

  8. Specific contribution of lamin A and lamin C in the development of laminopathies

    SciTech Connect

    Sylvius, Nicolas Hathaway, Andrea; Boudreau, Emilie; Gupta, Pallavi; Labib, Sarah; Bolongo, Pierrette M.; Rippstein, Peter; McBride, Heidi; Bilinska, Zofia T.; Tesson, Frederique

    2008-08-01

    Mutations in the lamin A/C gene are involved in multiple human disorders for which the pathophysiological mechanisms are partially understood. Conflicting results prevail regarding the organization of lamin A and C mutants within the nuclear envelope (NE) and on the interactions of each lamin to its counterpart. We over-expressed various lamin A and C mutants both independently and together in COS7 cells. When expressed alone, lamin A with cardiac/muscular disorder mutations forms abnormal aggregates inside the NE and not inside the nucleoplasm. Conversely, the equivalent lamin C organizes as intranucleoplasmic aggregates that never connect to the NE as opposed to wild type lamin C. Interestingly, the lamin C molecules present within these aggregates exhibit an abnormal increased mobility. When co-expressed, the complex formed by lamin A/C aggregates in the NE. Lamin A and C mutants for lipodystrophy behave similarly to the wild type. These findings reveal that lamins A and C may be differentially affected depending on the mutation. This results in multiple possible physiological consequences which likely contribute in the phenotypic variability of laminopathies. The inability of lamin C mutants to join the nuclear rim in the absence of lamin A is a potential pathophysiological mechanism for laminopathies.

  9. Postbuckling of laminated anisotropic panels

    NASA Technical Reports Server (NTRS)

    Jeffrey, Glenda L.

    1987-01-01

    A two-part study of the buckling and postbuckling of laminated anisotropic plates with bending-extensional coupling is presented. The first part involves the development and application of a modified Rayleigh-Ritz analysis technique. Modifications made to the classical technique can be grouped into three areas. First, known symmetries of anisotropic panels are exploited in the selection of approximation functions. Second, a reduced basis technique based on these same symmetries is applied in the linear range. Finally, geometric boundary conditions are enforced via an exterior penalty function approach, rather than relying on choice of approximation functions to satisfy these boundary conditions. Numerical results are presented for both the linear and nonlinear range, with additional studies made to determine the effect of variation in penalty parameter and number of basis vectors. In the second part, six panels possessing anisotropy and bending-extensional coupling are tested. Detailed comparisons are made between experiment and finite element results in order to gain insight into the postbuckling and failure characteristics of such panels. The panels are constructed using two different lamination sequences, and panels with three different aspect ratios were constructed for each lamination sequence.

  10. Mammalian telomeres and their partnership with lamins

    PubMed Central

    Burla, Romina; La Torre, Mattia; Saggio, Isabella

    2016-01-01

    ABSTRACT Chromosome ends are complex structures, which require a panel of factors for their elongation, replication, and protection. We describe here the mechanics of mammalian telomeres, dynamics and maintainance in relation to lamins. Multiple biochemical connections, including association of telomeres to the nuclear envelope and matrix, of telomeric proteins to lamins, and of lamin-associated proteins to chromosome ends, underline the interplay between lamins and telomeres. Paths toward senescence, such as defective telomere replication, altered heterochromatin organization, and impaired DNA repair, are common to lamins' and telomeres' dysfunction. The convergence of phenotypes can be interpreted through a model of dynamic, lamin-controlled functional platforms dedicated to the function of telomeres as fragile sites. The features of telomeropathies and laminopathies, and of animal models underline further overlapping aspects, including the alteration of stem cell compartments. We expect that future studies of basic biology and on aging will benefit from the analysis of this telomere-lamina interplay. PMID:27116558

  11. Laminate delamination due to thermal gradients

    SciTech Connect

    Hutchinson, J.W.; Lu, T.J.

    1995-10-01

    Flaw-induced delamination of orthotropic laminates subject to through-thickness temperature gradients is analyzed. A crack-like flaw impedes heat flow through the laminate, producing thermal stresses and crack tip stress intensities. The focus is on delamination cracks which propagate under steady-state conditions. The steady-state analysis becomes accurate for a crack whose length is about one laminate thickness. Moreover, the analysis provides realistic fail-safe criteria for excluding delamination.

  12. Geometrically nonlinear analysis of laminated elastic structures

    NASA Technical Reports Server (NTRS)

    Reddy, J. N.

    1984-01-01

    Laminated composite plates and shells that can be used to model automobile bodies, aircraft wings and fuselages, and pressure vessels among many other were analyzed. The finite element method, a numerical technique for engineering analysis of structures, is used to model the geometry and approximate the solution. Various alternative formulations for analyzing laminated plates and shells are developed and their finite element models are tested for accuracy and economy in computation. These include the shear deformation laminate theory and degenerated 3-D elasticity theory for laminates.

  13. Lamins at the crossroads of mechanosignaling

    PubMed Central

    Osmanagic-Myers, Selma; Dechat, Thomas

    2015-01-01

    The intermediate filament proteins, A- and B-type lamins, form the nuclear lamina scaffold adjacent to the inner nuclear membrane. B-type lamins confer elasticity, while A-type lamins lend viscosity and stiffness to nuclei. Lamins also contribute to chromatin regulation and various signaling pathways affecting gene expression. The mechanical roles of lamins and their functions in gene regulation are often viewed as independent activities, but recent findings suggest a highly cross-linked and interdependent regulation of these different functions, particularly in mechanosignaling. In this newly emerging concept, lamins act as a “mechanostat” that senses forces from outside and responds to tension by reinforcing the cytoskeleton and the extracellular matrix. A-type lamins, emerin, and the linker of the nucleoskeleton and cytoskeleton (LINC) complex directly transmit forces from the extracellular matrix into the nucleus. These mechanical forces lead to changes in the molecular structure, modification, and assembly state of A-type lamins. This in turn activates a tension-induced “inside-out signaling” through which the nucleus feeds back to the cytoskeleton and the extracellular matrix to balance outside and inside forces. These functions regulate differentiation and may be impaired in lamin-linked diseases, leading to cellular phenotypes, particularly in mechanical load-bearing tissues. PMID:25644599

  14. Symmetries in laminated composite plates

    NASA Technical Reports Server (NTRS)

    Noor, A. K.

    1976-01-01

    The different types of symmetry exhibited by laminated anisotropic fibrous composite plates are identified and contrasted with the symmetries of isotropic and homogeneous orthotropic plates. The effects of variations in the fiber orientation and the stacking sequence of the layers on the symmetries exhibited by composite plates are discussed. Both the linear and geometrically nonlinear responses of the plates are considered. A simple procedure is presented for exploiting the symmetries in the finite element analysis. Examples are given of square, skew and polygonal plates where use of symmetry concepts can significantly reduce the scope and cost of analysis.

  15. Impact damage in composite laminates

    NASA Technical Reports Server (NTRS)

    Grady, Joseph E.

    1988-01-01

    Damage tolerance requirements have become an important consideration in the design and fabrication of composite structural components for modern aircraft. The ability of a component to contain a flaw of a given size without serious loss of its structural integrity is of prime concern. Composite laminates are particularly susceptible to damage caused by transverse impact loading. The ongoing program described is aimed at developing experimental and analytical methods that can be used to assess damage tolerance capabilities in composite structures subjected to impulsive loading. Some significant results of this work and the methodology used to obtain them are outlined.

  16. Silicone modified resins for graphite fiber laminates

    NASA Technical Reports Server (NTRS)

    Frost, L. W.; Bower, G. M.

    1980-01-01

    Six silicone modified resins were selected for evaluation in unidirectional filament wound graphite laminates. Neat samples of these resins had 1,000 C char residues of 6-63%. The highest flexural values measured for the laminates were a strength of 1,220 MPa and a modulus of 105 GPa. The highest interlaminar shear strength was 72 MPa.

  17. Wettability of graphene-laminated micropillar structures

    NASA Astrophysics Data System (ADS)

    Bong, Jihye; Seo, Keumyoung; Park, Ji-Hoon; Ahn, Joung Real; Ju, Sanghyun

    2014-12-01

    The wetting control of graphene is of great interest for electronic, mechanical, architectural, and bionic applications. In this study, the wettability of graphene-laminated micropillar structures was manipulated by changing the height of graphene-laminated structures and employing the trichlorosilane (HDF-S)-based self-assembly monolayer. Graphene-laminated micropillar structures with HDF-S exhibited higher hydrophobicity (contact angle of 129.5°) than pristine graphene thin film (78.8°), pristine graphene-laminated micropillar structures (97.5°), and HDF-S self-assembled graphene thin film (98.5°). Wetting states of the graphene-laminated micropillar structure with HDF-S was also examined by using a urea solution, which flowed across the surface without leaving any residues.

  18. Universality of the frequency spectrum of laminates

    NASA Astrophysics Data System (ADS)

    Shmuel, Gal; Band, Ram

    2016-07-01

    We show that the frequency spectrum of two-component elastic laminates admits a universal structure, independent of the geometry of the periodic-cell and the specific physical properties. The compactness of the structure enables us to rigorously derive the maximal width, the expected width, and the density of the band-gaps - ranges of frequencies at which waves cannot propagate. In particular, we find that the density of these band-gaps is a universal property of classes of laminates. Rules for tailoring laminates according to desired spectrum properties thereby follow. We show that the frequency spectrum of various finitely deformed laminates are also endowed with the same compact structure. Finally, we explain how our results generalize for laminates with an arbitrary number of components, based on the form of their dispersion relation.

  19. Stationary turbine component with laminated skin

    DOEpatents

    James, Allister W.

    2012-08-14

    A stationary turbine engine component, such as a turbine vane, includes a internal spar and an external skin. The internal spar is made of a plurality of spar laminates, and the external skin is made of a plurality of skin laminates. The plurality of skin laminates interlockingly engage the plurality of spar laminates such that the external skin is located and held in place. This arrangement allows alternative high temperature materials to be used on turbine engine components in areas where their properties are needed without having to make the entire component out of such material. Thus, the manufacturing difficulties associated with making an entire component of such a material and the attendant high costs are avoided. The skin laminates can be made of advanced generation single crystal superalloys, intermetallics and refractory alloys.

  20. Wettability of graphene-laminated micropillar structures

    SciTech Connect

    Bong, Jihye; Seo, Keumyoung; Ju, Sanghyun E-mail: shju@kgu.ac.kr; Park, Ji-Hoon; Ahn, Joung Real E-mail: shju@kgu.ac.kr

    2014-12-21

    The wetting control of graphene is of great interest for electronic, mechanical, architectural, and bionic applications. In this study, the wettability of graphene-laminated micropillar structures was manipulated by changing the height of graphene-laminated structures and employing the trichlorosilane (HDF-S)-based self-assembly monolayer. Graphene-laminated micropillar structures with HDF-S exhibited higher hydrophobicity (contact angle of 129.5°) than pristine graphene thin film (78.8°), pristine graphene-laminated micropillar structures (97.5°), and HDF-S self-assembled graphene thin film (98.5°). Wetting states of the graphene-laminated micropillar structure with HDF-S was also examined by using a urea solution, which flowed across the surface without leaving any residues.

  1. Critical current of laminated and non-laminated BSCCO superconducting composite tape under bending strain

    NASA Astrophysics Data System (ADS)

    Matsubayashi, H.; Mukai, Y.; Arai, T.; Shin, J. K.; Ochiai, S.; Okuda, H.; Osamura, K.; Otto, A.; Malozemoff, A.

    2009-10-01

    It has been reported that, when the (Bi,Pb) 2Sr 2Ca 2Cu 3O x (hereafter noted as BSCCO)/Ag/Ag-alloy tape is laminated with stainless steel, the tensile strain tolerance of critical current is much improved. In this study, using the non-laminated and laminated BSCCO composite tapes fabricated at American Superconductor Corporation, the influences of lamination on the critical current and its distribution under bending strain were studied. The analysis of the measured variation of average critical current with bending strain based on the damage evolution model revealed that the laminated stainless steel acts to suppress the fracture of the BSCCO filaments. The experimentally observed high critical current retention of the laminated tape up to high bending strain was accounted for by the suppression of fracture of BSCCO filaments stated above and enhancement of the compressive residual strain in the filaments. The distributions of local critical current in non-laminated and laminated composite tape were described well by the three-parameter Weibull distribution function within the bending strain lower than 1.1%. The coefficient of variation of distribution of critical current of the laminated tape was similar to that of the non-laminated one under the same strain distribution in the core.

  2. Direct Composite Laminate Veneers: Three Case Reports

    PubMed Central

    Korkut, Bora; Yanıkoğlu, Funda; Günday, Mahir

    2013-01-01

    Re-establishing a patient’s lost dental esthetic appearance is one of the most important topics for contemporary dentistry. New treatment materials and methods have been coming on the scene, day by day, in order to achieve such an aim. Most dentists prefer more conservative and aesthetic approaches, such as direct and indirect laminate veneer restorations, instead of full-ceramic crowns for anteriors where aesthetics is really important. Laminate veneers are restorations which are envisioned to correct existing abnormalities, esthetic deficiencies and discolo-rations. Laminate veneer restorations may be processed in two different ways: direct or indirect. Direct laminate veneers have no need to be prepared in the laboratory and are based on the principle of application of a composite material directly to the prepared tooth surface in the dental clinic. Indirect laminate veneers may be produced from composite materials or ceramics, which are cemented to the tooth with an adhesive resin. In this case report, direct composite laminate veneer technique used for three patients with esthetic problems related to fractures, discolorations and an old prolapsed restoration, is described and six-month follow-ups are discussed. As a conclusion, direct laminate veneer restorations may be a treatment option for patients with the esthetic problems of anterior teeth in cases similar to those reported here. PMID:23875090

  3. Indentation law for composite laminates

    NASA Technical Reports Server (NTRS)

    Yang, S. H.

    1981-01-01

    Static indentation tests are described for glass/epoxy and graphite/epoxy composite laminates with steel balls as the indentor. Beam specimens clamped at various spans were used for the tests. Loading, unloading, and reloading data were obtained and fitted into power laws. Results show that: (1) contact behavior is not appreciably affected by the span; (2) loading and reloading curves seem to follow the 1.5 power law; and (3) unloading curves are described quite well by a 2.5 power law. In addition, values were determined for the critical indentation, alpha sub cr which can be used to predict permanent indentations in unloading. Since alpha sub cr only depends on composite material properties, only the loading and an unloading curve are needed to establish the complete loading-unloading-reloading behavior.

  4. Damage of hybrid composite laminates

    NASA Astrophysics Data System (ADS)

    Haery, Haleh A.; Kim, Ho Sung

    2013-08-01

    Hybrid laminates consisting of woven glass fabric/epoxy composite plies and woven carbon fabric/epoxy composite plies are studied for fatigue damage and residual strength. A theoretical framework based on the systems approach is proposed as a guide to deal with the complexity involving uncertainties and a large number of variables in the hybrid composite system. A relative damage sensitivity factor expression was developed for quantitative comparisons between non-hybrid and hybrid composites. Hypotheses derived from the theoretical framework were tested and verified. The first hypothesis was that the difference between two different sets of properties produces shear stress in interface between carbon fibre reinforced plastics (CRP) and glass fibre reinforced plastics (GRP), and eventually become a source for CRP/GRP interfacial delamination or longitudinal cracking. The second hypothesis was that inter-fibre bundle delamination occurs more severely to CRP sub-system than GRP sub-system.

  5. Systematic identification of pathological lamin A interactors

    PubMed Central

    Dittmer, Travis A.; Sahni, Nidhi; Kubben, Nard; Hill, David E.; Vidal, Marc; Burgess, Rebecca C.; Roukos, Vassilis; Misteli, Tom

    2014-01-01

    Laminopathies are a collection of phenotypically diverse diseases that include muscular dystrophies, cardiomyopathies, lipodystrophies, and premature aging syndromes. Laminopathies are caused by >300 distinct mutations in the LMNA gene, which encodes the nuclear intermediate filament proteins lamin A and C, two major architectural elements of the mammalian cell nucleus. The genotype–phenotype relationship and the basis for the pronounced tissue specificity of laminopathies are poorly understood. Here we seek to identify on a global scale lamin A–binding partners whose interaction is affected by disease-relevant LMNA mutations. In a screen of a human genome–wide ORFeome library, we identified and validated 337 lamin A–binding proteins. Testing them against 89 known lamin A disease mutations identified 50 disease-associated interactors. Association of progerin, the lamin A isoform responsible for the premature aging disorder Hutchinson–Gilford progeria syndrome, with its partners was largely mediated by farnesylation. Mapping of the interaction sites on lamin A identified the immunoglobulin G (IgG)–like domain as an interaction hotspot and demonstrated that lamin A variants, which destabilize the Ig-like domain, affect protein–protein interactions more globally than mutations of surface residues. Analysis of a set of LMNA mutations in a single residue, which result in three phenotypically distinct diseases, identified disease-specific interactors. The results represent a systematic map of disease-relevant lamin A interactors and suggest loss of tissue-specific lamin A interactions as a mechanism for the tissue-specific appearance of laminopathic phenotypes. PMID:24623722

  6. Systematic identification of pathological lamin A interactors.

    PubMed

    Dittmer, Travis A; Sahni, Nidhi; Kubben, Nard; Hill, David E; Vidal, Marc; Burgess, Rebecca C; Roukos, Vassilis; Misteli, Tom

    2014-05-01

    Laminopathies are a collection of phenotypically diverse diseases that include muscular dystrophies, cardiomyopathies, lipodystrophies, and premature aging syndromes. Laminopathies are caused by >300 distinct mutations in the LMNA gene, which encodes the nuclear intermediate filament proteins lamin A and C, two major architectural elements of the mammalian cell nucleus. The genotype-phenotype relationship and the basis for the pronounced tissue specificity of laminopathies are poorly understood. Here we seek to identify on a global scale lamin A-binding partners whose interaction is affected by disease-relevant LMNA mutations. In a screen of a human genome-wide ORFeome library, we identified and validated 337 lamin A-binding proteins. Testing them against 89 known lamin A disease mutations identified 50 disease-associated interactors. Association of progerin, the lamin A isoform responsible for the premature aging disorder Hutchinson-Gilford progeria syndrome, with its partners was largely mediated by farnesylation. Mapping of the interaction sites on lamin A identified the immunoglobulin G (IgG)-like domain as an interaction hotspot and demonstrated that lamin A variants, which destabilize the Ig-like domain, affect protein-protein interactions more globally than mutations of surface residues. Analysis of a set of LMNA mutations in a single residue, which result in three phenotypically distinct diseases, identified disease-specific interactors. The results represent a systematic map of disease-relevant lamin A interactors and suggest loss of tissue-specific lamin A interactions as a mechanism for the tissue-specific appearance of laminopathic phenotypes. PMID:24623722

  7. Flat laminated microbial mat communities

    NASA Astrophysics Data System (ADS)

    Franks, Jonathan; Stolz, John F.

    2009-10-01

    Flat laminated microbial mats are complex microbial ecosystems that inhabit a wide range of environments (e.g., caves, iron springs, thermal springs and pools, salt marshes, hypersaline ponds and lagoons, methane and petroleum seeps, sea mounts, deep sea vents, arctic dry valleys). Their community structure is defined by physical (e.g., light quantity and quality, temperature, density and pressure) and chemical (e.g., oxygen, oxidation/reduction potential, salinity, pH, available electron acceptors and donors, chemical species) parameters as well as species interactions. The main primary producers may be photoautotrophs (e.g., cyanobacteria, purple phototrophs, green phototrophs) or chemolithoautophs (e.g., colorless sulfur oxidizing bacteria). Anaerobic phototrophy may predominate in organic rich environments that support high rates of respiration. These communities are dynamic systems exhibiting both spatial and temporal heterogeneity. They are characterized by steep gradients with microenvironments on the submillimeter scale. Diel oscillations in the physical-chemical profile (e.g., oxygen, hydrogen sulfide, pH) and species distribution are typical for phototroph-dominated communities. Flat laminated microbial mats are often sites of robust biogeochemical cycling. In addition to well-established modes of metabolism for phototrophy (oxygenic and non-oxygenic), respiration (both aerobic and anaerobic), and fermentation, novel energetic pathways have been discovered (e.g., nitrate reduction couple to the oxidation of ammonia, sulfur, or arsenite). The application of culture-independent techniques (e.g., 16S rRNA clonal libraries, metagenomics), continue to expand our understanding of species composition and metabolic functions of these complex ecosystems.

  8. Severe laminitis in multiple zoo species.

    PubMed

    Wiedner, Ellen; Holland, Jeff; Trupkiewicz, John; Uzal, Francisco

    2014-01-01

    A 10-year record review from a zoological institution in the western USA identified four cases of severe laminitis resulting in rotation and protrusion of the third phalanx through the sole. Laminitis is reported in a Masai giraffe (Giraffa camelopardalis tippelskirchi), a Sichuan takin (Budorcas taxicolor tibetana), a greater Malayan chevrotain (Tragulus napu) and a giant eland (Taurotragus derbianus). This is the first report of severe laminitis with pedal bone rotation and protrusion in multiple species of non-domestic hoofstock, and the first report of this disease in three of these species (takin, chevrotain, and giant eland). PMID:24730432

  9. Probabilistic methods for the calculation of laminate properties

    SciTech Connect

    Mcmanus, H.L. )

    1993-06-01

    A method for calculating the properties of advanced composite laminates, including their variations due to known variations in the properties of the individual plies and the laminate geometry, is presented. The method is useful for understanding scatter in the measured properties of composite laminates. This scatter is particularly important in the design of ultra-low coefficient of thermal expansion (CTE) laminates. Such laminates are designed with a theoretically zero CTE, but in practice have a distribution of nonzero CTEs. Information useful for designing ultra-low expansion laminates is discussed. A practical limit on how close to zero the CTE of a laminate can be assumed to be is found. 10 refs.

  10. Free edge effects in laminated composites

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.

    1989-01-01

    The fundamental mechanics of free-edge effects in laminated fiber-reinforced composites is examined, reviewing the results of recent experimental and analytical investigations. The derivation of the governing equations for the basic problem is outlined, including the equilibrium and mismatch conditions and the elasticity formulation, and experimental data on axial displacement and shear strain in angle-ply laminates are summarized. Numerical predictions of free-edge deformation and interlaminar and through-thickness stress distributions are presented for cross-ply, angle-ply, and quasi-isotropic laminates, and the mechanisms of edge damage and failure in angle-ply laminates are briefly characterized. Extensive diagrams, drawings, graphs, and photographs are provided.

  11. Method for fabricating laminated uranium composites

    DOEpatents

    Chapman, L.R.

    1983-08-03

    The present invention is directed to a process for fabricating laminated composites of uranium or uranium alloys and at least one other metal or alloy. The laminated composites are fabricated by forming a casting of the molten uranium with the other metal or alloy which is selectively positioned in the casting and then hot-rolling the casting into a laminated plate in or around which the casting components are metallurgically bonded to one another to form the composite. The process of the present invention provides strong metallurgical bonds between the laminate components primarily since the bond disrupting surface oxides on the uranium or uranium alloy float to the surface of the casting to effectively remove the oxides from the bonding surfaces of the components.

  12. Behaviour of Mechanically Laminated CLT Members

    NASA Astrophysics Data System (ADS)

    Kuklík, P.; Velebil, L.

    2015-11-01

    Cross laminated timber (CLT) is one of the structural building systems based on the lamination of multiple layers, where each layer is oriented perpendicularly to each other. Recent requirements are placed to develop an alternative process based on the mechanical lamination of the layers, which is of particular interest to our research group at the University Centre for Energy Efficient Buildings. The goal is to develop and verify the behaviour of mechanically laminated CLT wall panels exposed to shear stresses in the plane. The shear resistance of mechanically jointed CLT is ensured by connecting the layers by screws. The paper deals with the experimental analysis focused on the determination of the torsional stiffness and the slip modulus of crossing areas for different numbers of orthogonally connected layers. The results of the experiments were compared with the current analytical model.

  13. Development of a laminate fatigue analysis

    NASA Technical Reports Server (NTRS)

    Roderick, G. L.; Obrien, T. K.; Whitcomb, J. D.

    1980-01-01

    A fatigue analysis technique developed to predict damage growth in notched laminates is described. Features of the analysis include: criteria to relate matrix failure to cyclic stresses in and between plies; correlation of delamination growth with strain-release rate; and in-plane shear modulus change is related to cyclic shear stresses. A simplified finite element model is used to determine stresses in laminates that contain matrix damage. Failure criteria are integrated with the finite element model to form the fatigue analysis.

  14. Lamin B1 and lamin B2 are long-lived proteins with distinct functions in retinal development.

    PubMed

    Razafsky, David; Ward, Candace; Potter, Chloe; Zhu, Wanqiu; Xue, Yunlu; Kefalov, Vladimir J; Fong, Loren G; Young, Stephen G; Hodzic, Didier

    2016-06-15

    Lamin B1 and lamin B2 are essential building blocks of the nuclear lamina, a filamentous meshwork lining the nucleoplasmic side of the inner nuclear membrane. Deficiencies in lamin B1 and lamin B2 impair neurodevelopment, but distinct functions for the two proteins in the development and homeostasis of the CNS have been elusive. Here we show that embryonic depletion of lamin B1 in retinal progenitors and postmitotic neurons affects nuclear integrity, leads to the collapse of the laminB2 meshwork, impairs neuronal survival, and markedly reduces the cellularity of adult retinas. In stark contrast, a deficiency of lamin B2 in the embryonic retina has no obvious effect on lamin B1 localization or nuclear integrity in embryonic retinas, suggesting that lamin B1, but not lamin B2, is strictly required for nucleokinesis during embryonic neurogenesis. However, the absence of lamin B2 prevents proper lamination of adult retinal neurons, impairs synaptogenesis, and reduces cone photoreceptor survival. We also show that lamin B1 and lamin B2 are extremely long-lived proteins in rod and cone photoreceptors. OF interest, a complete absence of both proteins during postnatal life has little or no effect on the survival and function of cone photoreceptors. PMID:27075175

  15. Lamin B1 and lamin B2 are long-lived proteins with distinct functions in retinal development

    PubMed Central

    Razafsky, David; Ward, Candace; Potter, Chloe; Zhu, Wanqiu; Xue, Yunlu; Kefalov, Vladimir J.; Fong, Loren G.; Young, Stephen G.; Hodzic, Didier

    2016-01-01

    Lamin B1 and lamin B2 are essential building blocks of the nuclear lamina, a filamentous meshwork lining the nucleoplasmic side of the inner nuclear membrane. Deficiencies in lamin B1 and lamin B2 impair neurodevelopment, but distinct functions for the two proteins in the development and homeostasis of the CNS have been elusive. Here we show that embryonic depletion of lamin B1 in retinal progenitors and postmitotic neurons affects nuclear integrity, leads to the collapse of the laminB2 meshwork, impairs neuronal survival, and markedly reduces the cellularity of adult retinas. In stark contrast, a deficiency of lamin B2 in the embryonic retina has no obvious effect on lamin B1 localization or nuclear integrity in embryonic retinas, suggesting that lamin B1, but not lamin B2, is strictly required for nucleokinesis during embryonic neurogenesis. However, the absence of lamin B2 prevents proper lamination of adult retinal neurons, impairs synaptogenesis, and reduces cone photoreceptor survival. We also show that lamin B1 and lamin B2 are extremely long-lived proteins in rod and cone photoreceptors. OF interest, a complete absence of both proteins during postnatal life has little or no effect on the survival and function of cone photoreceptors. PMID:27075175

  16. Lamination residual stresses in fiber composites

    NASA Technical Reports Server (NTRS)

    Daniel, I. M.; Liber, T.

    1975-01-01

    An experimental investigation was conducted to determine the magnitude of lamination residual stresses in angle-ply composites and to evaluate their effects on composite structural integrity. The materials investigated were boron/epoxy, boron/polyimide, graphite/low modulus epoxy, graphite/high modulus epoxy, graphite/polyimide and s-glass/epoxy. These materials were fully characterized. Static properties of laminates were also determined. Experimental techniques using embedded strain gages were developed and used to measure residual strains during curing. The extent of relaxation of lamination residual stresses was investigated. It was concluded that the degree of such relaxation is low. The behavior of angle-ply laminates subjected to thermal cycling, tensile load cycling, and combined thermal cycling with tensile load was investigated. In most cases these cycling programs did not have any measurable influence on residual strength and stiffness of the laminates. In the tensile load cycling tests, the graphite/polyimide shows the highest endurance with 10 million cycle runouts at loads up to 90 percent of the static strength.

  17. Mechanical Behavior of Fabric-Film Laminates

    NASA Technical Reports Server (NTRS)

    Said, Magdi S.

    1999-01-01

    Inflatable structures are gaining wide support in planetary scientific missions as well as commercial applications. For such applications a new class of materials made of laminating thin homogenous films to lightweight fabrics are being considered us structura1 gas envelops. The emerging composite materials are a result of recent advances in the manufacturing cf 1ightweight, high strength fibers, fabrics and scrims. The lamination of these load-carrying members with the proper gas barrier film results in wide range of materials suitable for various loading and environmental conditions. Polyester - based woven fabrics laminated to thin homogeneus film of polyester (Maylar) is an example of this class. This fabric/ film laminate is being considered for the development a material suitable for building large gas envelopes for use in the NASA Ultra Long Duration Balloon Program (ULDB). Compared to commercial homogeneus films, the material provides relatively high strength to weight ratio as well as better resistance to crack and tear propagation. The purpose of this papers is to introduce the mechanical behavior of this class of multi-layers composite and to highlight some of the concerns observed during the characterization of these laminate composites.

  18. Evaluation of Behaviours of Laminated Glass

    NASA Astrophysics Data System (ADS)

    Sable, L.; Japins, G.; Kalnins, K.

    2015-11-01

    Visual appearance of building facades and other load bearing structures, which now are part of modern architecture, is the reason why it is important to investigate in more detail the reliability of laminated glass for civil structures. Laminated glass in particular has become one of the trendy materials, for example Apple© stores have both load carrying capacity and transparent appearance. Glass has high mechanical strength and relatively medium density, however, the risk of sudden brittle failure like concrete or other ceramics determine relatively high conservatism in design practice of glass structures. This should be changed as consumer requirements evolve calling for a safe and reliable design methodology and corresponding building standards. A design methodology for glass and glass laminates should be urgently developed and included as a chapter in Eurocode. This paper presents initial experimental investigation of behaviour of simple glass sheets and laminated glass samples in 4-point bending test. The aim of the current research is to investigate laminated glass characteristic values and to verify the obtained experimental results with finite element method for glass and EVA material in line with future European Structural Design of Glass Components code.

  19. On thermal edge effects in composite laminates

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.

    1976-01-01

    Results are presented for a finite-element investigation of the combined influence of edge effects due to mechanical and thermal mismatch in composite laminates with free edges. Laminates of unidirectional boron/epoxy symmetrically bonded to sheets of aluminum and titanium were studied. It is shown that interlaminar thermal stresses may be more significant than the interlaminar stresses due to loading only. In addition, the stresses due to thermal mismatch may be of the same sign as those due to Poisson's mismatch or they may be of opposite sign depending upon material properties, stacking sequence, and direction of loading. The paper concludes with a brief discussion of thermal stresses in all-composite laminates.

  20. Damage initiation and propagation in metal laminates

    SciTech Connect

    Riddle, R.A.; Lesuer, D.R.; Syn, C.K.

    1996-07-26

    The metal laminates proposed here for aircraft structures are Al alloy interlayers between Al alloy based metal matrix composite (MMC) plates reinforced with Si carbide particles. Properties to be tailored for jet engine fan containment and wing and auxiliary support structures include the important property fracture toughness. A method was developed for simulating and predicting crack initiation/growth using finite element analysis and fracture mechanics. An important key in predicting the failure is the tie- break slideline with prescribed (chosen based on J Integral calculations) effective plastic strain to failure in elements along the slideline. More development of the method is needed, particularly in its correlation with experimental data from various fracture toughness and strength tests of metal laminates. Results show that delamination at the interface of the ductile interlayer and MMC material can add significantly to the energy required to propagate a crack through a metal laminate. 11 figs, 7 refs.

  1. Nonlinear effects on composite laminate thermal expansion

    NASA Technical Reports Server (NTRS)

    Hashin, Z.; Rosen, B. W.; Pipes, R. B.

    1979-01-01

    Analyses of Graphite/Polyimide laminates shown that the thermomechanical strains cannot be separated into mechanical strain and free thermal expansion strain. Elastic properties and thermal expansion coefficients of unidirectional Graphite/Polyimide specimens were measured as a function of temperature to provide inputs for the analysis. The + or - 45 degrees symmetric Graphite/Polyimide laminates were tested to obtain free thermal expansion coefficients and thermal expansion coefficients under various uniaxial loads. The experimental results demonstrated the effects predicted by the analysis, namely dependence of thermal expansion coefficients on load, and anisotropy of thermal expansion under load. The significance of time dependence on thermal expansion was demonstrated by comparison of measured laminate free expansion coefficients with and without 15 day delay at intermediate temperature.

  2. Plated lamination structures for integrated magnetic devices

    DOEpatents

    Webb, Bucknell C.

    2014-06-17

    Semiconductor integrated magnetic devices such as inductors, transformers, etc., having laminated magnetic-insulator stack structures are provided, wherein the laminated magnetic-insulator stack structures are formed using electroplating techniques. For example, an integrated laminated magnetic device includes a multilayer stack structure having alternating magnetic and insulating layers formed on a substrate, wherein each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by an insulating layer, and a local shorting structure to electrically connect each magnetic layer in the multilayer stack structure to an underlying magnetic layer in the multilayer stack structure to facilitate electroplating of the magnetic layers using an underlying conductive layer (magnetic or seed layer) in the stack as an electrical cathode/anode for each electroplated magnetic layer in the stack structure.

  3. Preliminary evaluation of hybrid titanium composite laminates

    NASA Technical Reports Server (NTRS)

    Miller, J. L.; Progar, D. J.; Johnson, W. S.; St.clair, T. L.

    1994-01-01

    In this study, the mechanical response of hybrid titanium composite laminates (HTCL) was evaluated at room and elevated temperatures. Also, the use of an elastic-plastic laminate analysis program for predicting the tensile response from constituent properties was verified. The improvement in mechanical properties achieved by the laminates was assessed by comparing the results of static strength and constant amplitude fatigue tests to those for monolithic titanium sheet. Two HTCL were fabricated with different fiber volume fractions, resin layer thicknesses, and resins. One panel was thicker and was more poorly bonded in comparison to other. Consequently, the former had a lower tensile strength, while fewer cracks grew in this panel and at a slower rate. Both panels showed an improvement in fatigue life of almost two orders of magnitude. The model predictions were also in good agreement with the experimental results for both HTCL panels.

  4. Silicone modified resins for graphite fiber laminates

    NASA Technical Reports Server (NTRS)

    Frost, L. W.; Bower, G. M.

    1979-01-01

    The development of silicon modified resins for graphite fiber laminates which will prevent the dispersal of graphite fibers when the composites are burned is discussed. Eighty-five silicone modified resins were synthesized and evaluated including unsaturated polyesters, thermosetting methacrylates, epoxies, polyimides, and phenolics. Neat resins were judged in terms of Si content, homogeneity, hardness, Char formation, and thermal stability. Char formation was estimated by thermogravimetry to 1,000 C in air and in N2. Thermal stability was evaluated by isothermal weight loss measurements for 200 hrs in air at three temperatures. Four silicone modified epoxies were selected for evaluation in unidirectional filament wound graphite laminates. Neat samples of these resins had 1,000 C char residues of 25 to 50%. The highest flexural values measured for the laminates were a strength of 140 kpsi and a modulus of 10 Mpsi. The highest interlaminar shear strength was 5.3 kpsi.

  5. Development of tough, moisture resistant laminating resins

    NASA Technical Reports Server (NTRS)

    Brand, R. A.; Harrison, E. S.

    1982-01-01

    Tough, moisture resistant laminating resins for employment with graphite fibers were developed. The new laminating resins exhibited cost, handleability and processing characteristics equivalent to 394K (250 F) curing epoxies. The laminating resins were based on bisphenol A dicyanate and monofunctional cyanates with hydrophobic substituents. These resins sorb only small quantities of moisture at equilibrium (0.5% or less) with minimal glass transition temperature depression and represent an improvement over epoxies which sorb around 2% moisture at equilibrium. Toughening was accomplished by the precipitation of small diameter particles of butadiene nitrile rubber throughout the resin matrix. The rubber domains act as microcrack termini and energy dissipation sites, allowing increased stress accommodation prior to catastrophic failure. A unique blend of amine terminated butadiene nitrile elastomer (MW 2,000) and a high nitrile content butadiene nitrile rubber yielded the desired resin morphology.

  6. Structural reliability analysis of laminated CMC components

    NASA Technical Reports Server (NTRS)

    Duffy, Stephen F.; Palko, Joseph L.; Gyekenyesi, John P.

    1991-01-01

    For laminated ceramic matrix composite (CMC) materials to realize their full potential in aerospace applications, design methods and protocols are a necessity. The time independent failure response of these materials is focussed on and a reliability analysis is presented associated with the initiation of matrix cracking. A public domain computer algorithm is highlighted that was coupled with the laminate analysis of a finite element code and which serves as a design aid to analyze structural components made from laminated CMC materials. Issues relevant to the effect of the size of the component are discussed, and a parameter estimation procedure is presented. The estimation procedure allows three parameters to be calculated from a failure population that has an underlying Weibull distribution.

  7. Stochastic damage evolution in textile laminates

    NASA Technical Reports Server (NTRS)

    Dzenis, Yuris A.; Bogdanovich, Alexander E.; Pastore, Christopher M.

    1993-01-01

    A probabilistic model utilizing random material characteristics to predict damage evolution in textile laminates is presented. Model is based on a division of each ply into two sublaminas consisting of cells. The probability of cell failure is calculated using stochastic function theory and maximal strain failure criterion. Three modes of failure, i.e. fiber breakage, matrix failure in transverse direction, as well as matrix or interface shear cracking, are taken into account. Computed failure probabilities are utilized in reducing cell stiffness based on the mesovolume concept. A numerical algorithm is developed predicting the damage evolution and deformation history of textile laminates. Effect of scatter of fiber orientation on cell properties is discussed. Weave influence on damage accumulation is illustrated with the help of an example of a Kevlar/epoxy laminate.

  8. Elastic constants of layers in isotropic laminates.

    PubMed

    Heyliger, Paul R; Ledbetter, Hassel; Kim, Sudook; Reimanis, Ivar

    2003-11-01

    The individual laminae elastic constants in multilayer laminates composed of dissimilar isotropic layers were determined using ultrasonic-resonance spectroscopy and the linear theory of elasticity. Ultrasonic resonance allows one to measure the free-vibration response spectrum of a traction-free solid under periodic vibration. These frequencies depend on pointwise density, laminate dimensions, layer thickness, and layer elastic constants. Given a material with known mass but unknown constitution, this method allows one to extract the elastic constants and density of the constituent layers. This is accomplished by measuring the frequencies and then minimizing the differences between these and those calculated using the theory of elasticity for layered media to select the constants that best replicate the frequency-response spectrum. This approach is applied to a three-layer, unsymmetric laminate of WpCu, and very good agreement is found with the elastic constants of the two constituent materials. PMID:14649998

  9. Adhesives for laminating polyimide insulated flat conductor cable

    NASA Technical Reports Server (NTRS)

    Montermoso, J. C.; Saxton, T. R.; Taylor, R. L.

    1967-01-01

    Polymer adhesive laminates polyimide-film flat conductor cable. It is obtained by reacting an appropriate diamine with a dianhydride. The adhesive has also been used in the lamination of copper to copper for the preparation of multilayer circuit boards.

  10. Fracture behavior of laminated discontinuously reinforced aluminum material

    SciTech Connect

    Osman, T.M. |; Lewandowski, J.J.; Lesuer, D.R.; Syn, C.K.; Hunt, W.H. Jr

    1994-05-01

    Laminated metallic composites are being developed for applications which require high specific stiffness and fracture resistance. Recent work with laminated discontinuously reinforced aluminum (DRA) materials has demonstrated the potential for marked improvements in stable crack growth resistance via extrinsic toughening. The purpose of this work is to compare the fracture mechanisms and fracture resistance of laminated DRA materials to unlaminated DRA materials. In particular, the production of extensive stable crack growth and the associated improvement in damage tolerance in DRA laminates is documented.

  11. Reliability analysis of continuous fiber composite laminates

    NASA Technical Reports Server (NTRS)

    Thomas, David J.; Wetherhold, Robert C.

    1991-01-01

    This paper describes two methods, the maximum distortion energy (MDE) and the principle of independent action (PIA), developed for the analysis of the reliability of a single continuous composite lamina. It is shown that, for the typical laminated plate structure, the individual lamina reliabilities can be combined in order to produce the upper and the lower bounds of reliability for the laminate, similar in nature to the bounds on properties produced from variational elastic methods. These limits were derived for both the interactive and the model failure considerations. Analytical expressions were also derived for the sensitivity of the reliability limits with respect to changes in the Weibull parameters and in loading conditions.

  12. Composite laminate free edge reinforcement concepts

    NASA Technical Reports Server (NTRS)

    Howard, W. E.; Gossard, T., Jr.; Jones, R. M.

    1985-01-01

    The presence of a free edge in a laminated composite structure can result in delamination of the composite under certain loading conditions. Linear finite element analysis predicts large or even singular interlaminar stresses near the free edge. Edge reinforcements which will reduce these interlaminar stresses, prevent or delay the onset of delaminations, and thereby increase the strength and life of the structure were studied. Finite element models are used to analyze reinforced laminates which were subsequently fabricated and loaded to failure in order to verify the analysis results.

  13. Ultrasonic transducer with laminated coupling wedge

    DOEpatents

    Karplus, Henry H. B.

    1976-08-03

    An ultrasonic transducer capable of use in a high-temperature environment incorporates a laminated metal coupling wedge including a reflecting edge shaped as a double sloping roof and a transducer crystal backed by a laminated metal sound absorber disposed so as to direct sound waves through the coupling wedge and into a work piece, reflections from the interface between the coupling wedge and the work piece passing to the reflecting edge. Preferably the angle of inclination of the two halves of the reflecting edge are different.

  14. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    SciTech Connect

    Allan, Shawn M; Baranova, Inessa; Poley, Joseph; Reis, Henrique

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North

  15. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    SciTech Connect

    Allan, Shawn M.

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North

  16. Multi-layer laminate structure and manufacturing method

    SciTech Connect

    Keenihan, James R.; Cleereman, Robert J.; Eurich, Gerald; Graham, Andrew T.; Langmaid, Joe A.

    2013-01-29

    The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

  17. Multi-layer laminate structure and manufacturing method

    DOEpatents

    Keenihan, James R.; Cleereman, Robert J.; Eurich, Gerald; Graham, Andrew T.; Langmaid, Joe A.

    2012-04-24

    The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

  18. Reliability analysis of continuous fiber composite laminates

    NASA Technical Reports Server (NTRS)

    Thomas, David J.; Wetherhold, Robert C.

    1990-01-01

    A composite lamina may be viewed as a homogeneous solid whose directional strengths are random variables. Calculation of the lamina reliability under a multi-axial stress state can be approached by either assuming that the strengths act separately (modal or independent action), or that they interact through a quadratic interaction criterion. The independent action reliability may be calculated in closed form, while interactive criteria require simulations; there is currently insufficient data to make a final determination of preference between them. Using independent action for illustration purposes, the lamina reliability may be plotted in either stress space or in a non-dimensional representation. For the typical laminated plate structure, the individual lamina reliabilities may be combined in order to produce formal upper and lower bounds of reliability for the laminate, similar in nature to the bounds on properties produced from variational elastic methods. These bounds are illustrated for a (0/plus or minus 15)sub s Graphite/Epoxy (GR/EP) laminate. And addition, simple physically plausible phenomenological rules are proposed for redistribution of load after a lamina has failed. These rules are illustrated by application to (0/plus or minus 15)sub s and (90/plus or minus 45/0)sub s GR/EP laminates and results are compared with respect to the proposed bounds.

  19. Doped LZO buffer layers for laminated conductors

    DOEpatents

    Paranthaman, Mariappan Parans [Knoxville, TN; Schoop, Urs [Westborough, MA; Goyal, Amit [Knoxville, TN; Thieme, Cornelis Leo Hans [Westborough, MA; Verebelyi, Darren T [Oxford, MA; Rupich, Martin W [Framingham, MA

    2010-03-23

    A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the substrate, the biaxially textured buffer layer comprising LZO and a dopant for mitigating metal diffusion through the LZO, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.

  20. Laminated insulators having heat dissipation means

    DOEpatents

    Niemann, R.C.; Mataya, K.F.; Gonczy, J.D.

    1980-04-24

    A laminated body is provided with heat dissipation capabilities. The insulator body is formed by dielectric layers interleaved with heat conductive layers, and bonded by an adhesive to form a composite structure. The heat conductive layers include provision for connection to an external thermal circuit.

  1. Compression failure of angle-ply laminates

    NASA Technical Reports Server (NTRS)

    Peel, Larry D.; Hyer, Michael W.; Shuart, Mark J.

    1991-01-01

    The present work deals with modes and mechanisms of failure in compression of angle-ply laminates. Experimental results were obtained from 42 angle-ply IM7/8551-7a specimens with a lay-up of ((plus or minus theta)/(plus or minus theta)) sub 6s where theta, the off-axis angle, ranged from 0 degrees to 90 degrees. The results showed four failure modes, these modes being a function of off-axis angle. Failure modes include fiber compression, inplane transverse tension, inplane shear, and inplane transverse compression. Excessive interlaminar shear strain was also considered as an important mode of failure. At low off-axis angles, experimentally observed values were considerably lower than published strengths. It was determined that laminate imperfections in the form of layer waviness could be a major factor in reducing compression strength. Previously developed linear buckling and geometrically nonlinear theories were used, with modifications and enhancements, to examine the influence of layer waviness on compression response. The wavy layer is described by a wave amplitude and a wave length. Linear elastic stress-strain response is assumed. The geometrically nonlinear theory, in conjunction with the maximum stress failure criterion, was used to predict compression failure and failure modes for the angle-ply laminates. A range of wave length and amplitudes were used. It was found that for 0 less than or equal to theta less than or equal to 15 degrees failure was most likely due to fiber compression. For 15 degrees less than theta less than or equal to 35 degrees, failure was most likely due to inplane transverse tension. For 35 degrees less than theta less than or equal to 70 degrees, failure was most likely due to inplane shear. For theta less than 70 degrees, failure was most likely due to inplane transverse compression. The fiber compression and transverse tension failure modes depended more heavily on wave length than on wave amplitude. Thus using a single

  2. Edge effects in angle-ply composite laminates

    NASA Technical Reports Server (NTRS)

    Hsu, P. W.; Herakovich, C. T.

    1977-01-01

    This paper presents the results of a zeroth-order solution for edge effects in angle-ply composite laminates obtained using perturbation techniques and a limiting free body approach. The general solution for edge effects in laminates of arbitrary angle ply is applied to the special case of a (+ or - 45)s graphite/epoxy laminate. Interlaminar stress distributions are obtained as a function of the laminate thickness-to-width ratio and compared to finite difference results. The solution predicts stable, continuous stress distributions, determines finite maximum tensile interlaminar normal stress and provides mathematical evidence for singular interlaminar shear stresses in (+ or - 45) graphite/epoxy laminates.

  3. Fatigue damage development of various CFRP-laminates

    NASA Technical Reports Server (NTRS)

    Schulte, K.; Baron, CH.

    1988-01-01

    The chronic strength and fatigue behavior of a woven carbon-fiber reinforced laminate in a balanced eight-shaft satin weave style was compared to nonwoven laminates with an equivalent cross-ply layup. Half the fibers were arranged in the direction of the load and the other half perpendicular to it. Two types of nonwoven laminates consisting of continuous fibers and aligned discontinuous fibers, both produced from carbon fiber prepregs, were studied. The cross-ply laminate with continuous fiber showed the best characteristics with regard to both static strength and fatigue. The similarities and differences in damage mechanisms in the laminates are described.

  4. Nonlinear laminate analysis for metal matrix fiber composites

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1981-01-01

    A nonlinear laminate analysis is described for predicting the mechanical behavior (stress-strain relationships) of angle-ply laminates in which the matrix is strained nonlinearly by both the residual stress and the mechanical load and in which additional nonlinearities are induced due to progressive fiber fractures and ply relative rotations. The nonlinear laminate analysis is based on linear composite mechanics and a piece-wise linear laminate analysis to handle the nonlinear responses. Results obtained by using this nonlinear analysis on boron-fiber/aluminum-matrix angle-ply laminates agree well with experimental data. The results shown illustrate the in situ ply stress-strain behavior and synergistic strength enhancement.

  5. Nonlinear laminate analysis for metal matrix fiber composites

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1981-01-01

    A nonlinear laminate analysis is described for predicting the mechanical behavior (stress-strain relationships) of angleplied laminates in which the matrix is strained nonlinearly by both the residual stress and the mechanical load and in which additional nonlinearities are induced due to progressive fiber fractures and ply relative rotations. The nonlinear laminate analysis (NLA) is based on linear composite mechanics and a piece wise linear laminate analysis to handle the nonlinear responses. Results obtained by using this nonlinear analysis on boron fiber/aluminum matrix angleplied laminates agree well with experimental data. The results shown illustrate the in situ ply stress-strain behavior and synergistic strength enhancement.

  6. Progressive delamination in polymer matrix composite laminates: A new approach

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Murthy, P. L. N.; Minnetyan, L.

    1992-01-01

    A new approach independent of stress intensity factors and fracture toughness parameters has been developed and is described for the computational simulation of progressive delamination in polymer matrix composite laminates. The damage stages are quantified based on physics via composite mechanics while the degradation of the laminate behavior is quantified via the finite element method. The approach accounts for all types of composite behavior, laminate configuration, load conditions, and delamination processes starting from damage initiation, to unstable propagation, and to laminate fracture. Results of laminate fracture in composite beams, panels, plates, and shells are presented to demonstrate the effectiveness and versatility of this new approach.

  7. Determining Shear Stress Distribution in a Laminate

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.

    2010-01-01

    A "simplified shear solution" method approximates the through-thickness shear stress distribution within a composite laminate based on an extension of laminated beam theory. The method does not consider the solution of a particular boundary value problem; rather, it requires only knowledge of the global shear loading, geometry, and material properties of the laminate or panel. It is thus analogous to lamination theory in that ply-level stresses can be efficiently determined from global load resultants at a given location in a structure and used to evaluate the margin of safety on a ply-by-ply basis. The simplified shear solution stress distribution is zero at free surfaces, continuous at ply boundaries, and integrates to the applied shear load. The method has been incorporated within the HyperSizer commercial structural sizing software to improve its predictive capability for designing composite structures. The HyperSizer structural sizing software is used extensively by NASA to design composite structures. In the case of through-thickness shear loading on panels, HyperSizer previously included a basic, industry-standard, method for approximating the resulting shear stress distribution in sandwich panels. However, no such method was employed for solid laminate panels. The purpose of the innovation is to provide an approximation of the through-thickness shear stresses in a solid laminate given the through-thickness shear loads (Qx and Qy) on the panel. The method was needed for implementation within the HyperSizer structural sizing software so that the approximated ply-level shear stresses could be utilized in a failure theory to assess the adequacy of a panel design. The simplified shear solution method was developed based on extending and generalizing bi-material beam theory to plate-like structures. It is assumed that the through-thickness shear stresses arise due to local bending of the laminate induced by the through-thickness shear load, and by imposing

  8. Tensile stress-strain behavior of boron/aluminum laminates

    NASA Technical Reports Server (NTRS)

    Sova, J. A.; Poe, C. C., Jr.

    1978-01-01

    The tensile stress-strain behavior of five types of boron/aluminum laminates was investigated. Longitudinal and transverse stress-strain curves were obtained for monotonic loading to failure and for three cycles of loading to successively higher load levels. The laminate strengths predicted by assuming that the zero deg plies failed first correlated well with the experimental results. The stress-strain curves for all the boron/aluminum laminates were nonlinear except at very small strains. Within the small linear regions, elastic constants calculated from laminate theory corresponded to those obtained experimentally to within 10 to 20 percent. A limited amount of cyclic loading did not affect the ultimate strength and strain for the boron/aluminum laminates. The laminates, however, exhibited a permanent strain on unloading. The Ramberg-Osgood equation was fitted to the stress-strain curves to obtain average curves for the various laminates.

  9. Ultrasonic monitoring of asymmetric carbon fibre reinforced aluminum laminates

    NASA Astrophysics Data System (ADS)

    Zhao, Junqing; Yang, Fan; Wang, Rongguo

    2013-08-01

    Asymmetric carbon fibre reinforced aluminum alloy laminates was manufactured for the purpose with repeat tensile test, which will be applied in composite pressure vessel. Ultrasonic C scan and A scan approach are used to evaluate the damage of the asymmetric CFRP-Al (carbon fibre reinforced aluminum alloy) laminates. Nondestructive detection is carried out for the CFRP-Al laminates before and after tensile test. Comparison results and pulse echo analysis show that when subjected to repeat tensile test with 70% elastic limit strain load of the CFRP laminates, the interface debonding between CFRP and Al will not occur but the delamination within CFRP laminates becomes the main damage of the asymmetric CFRP-Al laminates. This investigation indicated that combined ultrasonic C scan and A scan is available for damage evaluation of fibre metal laminates.

  10. Novel Remanufacturing Process of Recycled Polytetrafluoroethylene(PTFE)/GF Laminate

    NASA Astrophysics Data System (ADS)

    Xi, Z.; Ghita, O. R.; Johnston, P.; Evans, K. E.

    2011-01-01

    Currently, the PTFE/GF laminate and PTFE PCB manufacturers are under considerable pressure to address the recycling issues due to Waste Electrical and Electronic Equipment (WEEE) Directive, shortage of landfill capacity and cost of disposal. This study is proposing a novel manufacture method for reuse of the mechanical ground PTFE/Glass fibre (GF) laminate and production of the first reconstitute PTFE/GF laminate. The reconstitute PTFE/GF laminate proposed here consists of a layer of recycled sub-sheet, additional layers of PTFE and PTFE coated glass cloth, also covered by copper foils. The reconstitute PTFE/GF laminate showed good dielectric properties. Therefore, there is potential to use the mechanical ground PTFE/GF laminate powder to produce reconstitute PTFE/GF laminate, for use in high frequencies PCB applications.

  11. A study of adhesion at the E-glass/FR4 interface

    SciTech Connect

    Kent, M.S.; Baca, P.; McNamara, W.F.

    1995-12-31

    The goal of this work is to investigate mechanisms for the loss of adhesive strength between E-glass and FR4 epoxy upon-humidity and temperature conditioning. In this paper we discuss the distribution of moisture between the interface region and the bulk epoxy examined by neutron reflection, and the relationship of this data to adhesive strength.

  12. Micromechanical Modeling of Impact Damage Mechanisms in Unidirectional Composite Laminates

    NASA Astrophysics Data System (ADS)

    Meng, Qinghua; Wang, Zhenqing

    2016-05-01

    Composite laminates are susceptible to the transverse impact loads resulting in significant damage such as matrix cracking, fiber breakage and delamination. In this paper, a micromechanical model is developed to predict the impact damage of composite laminates based on microstructure and various failure models of laminates. The fiber and matrix are represented by the isotropic and elastic-plastic solid, and their impact failure behaviors are modeled based on shear damage model. The delaminaton failure is modeling by the interface element controlled by cohesive damage model. Impact damage mechanisms of laminate are analyzed by using the micromechanical model proposed. In addition, the effects of impact energy and laminated type on impact damage behavior of laminates are investigated. Due to the damage of the surrounding matrix near the impact point caused by the fiber deformation, the surface damage area of laminate is larger than the area of ​​impact projectile. The shape of the damage area is roughly rectangle or elliptical with the major axis extending parallel to the fiber direction in the surface layer of laminate. The alternating laminated type with two fiber directions is more propitious to improve the impact resistance of laminates.

  13. Thermal stresses in thick laminated composite shells

    NASA Technical Reports Server (NTRS)

    Yuan, F. G.

    1993-01-01

    The paper provides an analytical formulation to investigate the thermomechanical behavior of thick composite shells subjected to a temperature distribution which varies arbitrarily in the radial direction. For illustrative purposes, shells under uniform temperature change are presented. It is found that thermal twist would occur even for symmetric laminated shells. Under uniform temperature rise, results for off-axis graphite/epoxy shells show that extensional-shear coupling can cause tensile radial stress throughout the shell and tensile hoop stress in the inner region. Laminated graphite/epoxy shells can exhibit negative effective thermal expansion coefficients in the longitudinal and transverse directions. Finally, the stacking sequence has a strong influence on the thermal stress distributions.

  14. Transverse shear stiffness of laminated anisotropic shells

    NASA Technical Reports Server (NTRS)

    Cohen, G. A.

    1978-01-01

    Equations are derived for the transverse shear stiffness of laminated anisotropic shells. Without making assumptions for thickness distribution for either transverse shear stresses or strains, constitutive equations for the transverse shear deformation theory of anisotropic heterogeneous shells are found. The equations are based on Taylor series expansions about a generic point for stress resultants and couples, identically satisfying plate equilibrium equations. These equations are used to find statically correct expressions for in-surface stresses, transverse shear stresses, and the area density of transverse shear strain energy, in terms of transverse shear stress resultants and redundants. The application of Castigliano's theorem of least work minimizes shear strain energy with respect to the redundants. Examples are presented for several laminated walls. Good agreement is found between the results and those of exact three-dimensional elasticity solutions for the cylindrical bending of a plate.

  15. Indirect laminate veneer: a conservative novel approach.

    PubMed

    Prajapati, Paranjay; Sethuraman, Rajesh; Naveen, Y G; Patel, Jayanti R

    2013-01-01

    Various treatment options and materials are available for restoration of an endodontically treated tooth. Laminate veneer is conservative treatment usually employed for aesthetic correction or improvement. The indirect composite is available in a wide range of shades and specific characterisation is easily performed chair side in the operatory area, which makes it a quick procedure and time saving for both the patient and the dentist. The physical properties and optical properties are good enough to use it as indirect restorative material, so in this particular case it was the material of choice for fabrication of laminate veneer on anterior tooth. In this case, the endodontically treated tooth with a fractured incisal edge was restored with indirect composite material. PMID:23975914

  16. Investigating Delamination Migration in Composite Tape Laminates

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.; DeCarvalho, Nelson V.

    2014-01-01

    A modification to a recently developed test specimen designed to investigate migration of a delamination between neighboring ply interfaces in tape laminates is presented. The specimen is a cross-ply laminated beam consisting of 40 plies with a polytetrafluoroethylene insert spanning part way along its length. The insert is located between a lower 0-degree ply (specimen length direction) and a stack of four 90-degree plies (specimen width direction). The modification involved a stacking sequence that promotes stable delamination growth prior to migration, and included a relocation of the insert from the specimen midplane to the interface between plies 14 and 15. Specimens were clamped at both ends onto a rigid baseplate and loaded on their upper surface via a piano hinge assembly, resulting in a predominantly flexural loading condition. Tests were conducted with the load-application point positioned at various locations along a specimen's span. This position affected the sequence of damage events during a test.

  17. Laminated grid and web magnetic cores

    DOEpatents

    Sefko, John; Pavlik, Norman M.

    1984-01-01

    A laminated magnetic core characterized by an electromagnetic core having core legs which comprise elongated apertures and edge notches disposed transversely to the longitudinal axis of the legs, such as high reluctance cores with linear magnetization characteristics for high voltage shunt reactors. In one embodiment the apertures include compact bodies of microlaminations for more flexibility and control in adjusting permeability and/or core reluctance.

  18. Nondimensional impact models for composite laminates

    NASA Technical Reports Server (NTRS)

    Sankar, B. V.; Nguyen, P. T.; Ku, C.

    1990-01-01

    The equations governing the problem of low-velocity impact of a simply supported rectangular laminated plate are nondimensionalized such that the problem is defined in terms of five dimensionless parameters. A parametric study using the Graeco-Latin Factorial Plan is performed. Semi-empirical formulas for maximum impact force, impact duration, and maximum back surface strains are obtained. It is found that some of the simple impact models provide the bounds for the case of impact on a finite extent plate.

  19. Process Yields Strong, Void-Free Laminates

    NASA Technical Reports Server (NTRS)

    Bryant, L. E.; Covington, E. W., III; Dale, W. J.; Hall, E. T., Jr; Justice, J. E.; Taylor, E. C.; Wilson, M. L.

    1983-01-01

    Need for lightweight materials as structural components for future space transportation systems stimulated development of systematic method for manufacturing a polyimide/graphite composite. Laminates manufactured by process are void-free, exhibit excellent thermo-oxidative stability up to 315 degrees C (600 degrees F) and are 40 percent lighter than aluminum. Process is precise, repeatable, and ideally suited for researchers and small-lot producers of composite materials.

  20. Triangular Element For Analyzing Elasticity Of Laminates

    NASA Technical Reports Server (NTRS)

    Martin, C. Wayne; Lung, S. F.; Gupta, K. K.

    1991-01-01

    Flat triangular element developed for use in finite-element analyses of stress and strain in laminated plates made of such materials as plywood or advanced fiber/epoxy composite materials. Has multiple layers, each of which can have different isotropic or orthotropic elastic properties. Many such elements used in finite-element mesh to calculate stiffness of plate. Formulation of element straight-forward, and calculation of its stiffness matrix simple and fast.

  1. Distributed dynamic load on composite laminates

    NASA Astrophysics Data System (ADS)

    Langella, A.; Lopresto, V.; Caprino, G.

    2016-05-01

    An experimental activity conducted in order to assess the impact behavior at room and low temperature of carbon fibre in vinylester resin laminates used in the shipbuilding industry, was reported. The conditions which reproduce the impact of a hull at low temperature with a solid body suspended in the water was reproduced. A test equipment was designed and realized to reproduce the real material behaviour in water to obtain a load distribution on the entire surface of the specimen. The results were obtained impacting the laminates placed between the cilyndrical steel impactor and a bag containing water. A falling weight machine, equipped with an instrumented steel impactor and a thermal chamber, was adopted for the experimental tests. The impact behaviour in hostile environments was compared to the behaviour at room temperature and the data obtained under distributed load conditions were compared with the results from concentrated loads: a completely different behaviour was observed between the two different loading conditions in terms of load-displacement curve. The effect of the impact on the laminates has been related with the delaminations, evaluated by ultrasonic scanning, and the indentation.

  2. Characteristics of laminates with delamination control strips

    NASA Technical Reports Server (NTRS)

    Sun, C. T.; Goering, J. C.; Alper, J. M.; Gause, L. W.

    1992-01-01

    Tough resin is needed to resist delamination crack propagation. However, modulus often has to be compromised because it is difficult to retain both high modulus and toughness in a matrix material. A potential solution is to use a hybrid system in which tough resin strips are included within a conventional matrix composite. By adjusting the spacing of the tough resin strips, maximum delamination size can be controlled. Experimental results for impact damage and subsequent damage propagation in laminates containing tough resin strips are reported. Plain adhesive strips and fiber-reinforced tough resin composite strips were used in constructing the hybrid laminates. Test results indicated that size of delamination inflicted by impact was confined between the tough resin strips. As a result, significantly increased residual compressive strength was obtained. Impacted laminates containing tough resin strips were also fatigue tested. It was found that these strips reduced the growth of the impact damage area relative to the growth seen in coupons with no tough resin strips. Damage growth from an open hole under tension fatigue was evaluated using both tough resin strips and glass fiber reinforced tough resin strips. Unreinforced tough resin strips retarded delamination growth from the open hole, but did not stop matrix cracks growing in the fiber direction. Fiber reinforced tough resin strips did not contain axial delamination growth from the open hole. However, they did act as crack arresters, stopping the through-the-thickness tension crack originating from the hole.

  3. Modeling Composite Laminate Crushing for Crash Analysis

    NASA Technical Reports Server (NTRS)

    Fleming, David C.; Jones, Lisa (Technical Monitor)

    2002-01-01

    Crash modeling of composite structures remains limited in application and has not been effectively demonstrated as a predictive tool. While the global response of composite structures may be well modeled, when composite structures act as energy-absorbing members through direct laminate crushing the modeling accuracy is greatly reduced. The most efficient composite energy absorbing structures, in terms of energy absorbed per unit mass, are those that absorb energy through a complex progressive crushing response in which fiber and matrix fractures on a small scale dominate the behavior. Such failure modes simultaneously include delamination of plies, failure of the matrix to produce fiber bundles, and subsequent failure of fiber bundles either in bending or in shear. In addition, the response may include the significant action of friction, both internally (between delaminated plies or fiber bundles) or externally (between the laminate and the crushing surface). A figure shows the crushing damage observed in a fiberglass composite tube specimen, illustrating the complexity of the response. To achieve a finite element model of such complex behavior is an extremely challenging problem. A practical crushing model based on detailed modeling of the physical mechanisms of crushing behavior is not expected in the foreseeable future. The present research describes attempts to model composite crushing behavior using a novel hybrid modeling procedure. Experimental testing is done is support of the modeling efforts, and a test specimen is developed to provide data for validating laminate crushing models.

  4. Hygrothermal stability of laminated CFRP composite mirrors

    NASA Astrophysics Data System (ADS)

    Pryor, Mark K.

    2000-07-01

    This paper is intended to address accuracy issues associated with hygrothermal stability of ultra-lightweight composite mirror structures. Hygrothermal stability of a mirror is ultimately defined as its optical performance when subjected to temperature or moisture variations. Stability is dictated by a combination of material behavior and geometric configuration. Ideally, an isotropic material could be used that is lightweight, has high stiffness, and has no response to temperature or moisture variances. This type of material would therefore be independent of geometry. Quasi-isotropic laminated CFRP composite materials offer most of these characteristics, but are transversely isotropic with near zero hygrothermal response in the plane of the laminate and a relatively high response through the thickness. Typically, mirrors made from laminated material consist of a thin curved shell supported by an array of ribs. Interference problems arise at the rib/shell interface resulting in a `print-through' effect by the ribs. Also, adhesive used to bond the ribs to the shell pull the shell causing additional `print-through'. Additional sources of instabilities result from material variances, processing, and assembly. These multiple sources of instabilities superimpose onto each other resulting in the structures overall hygrothermal stability.

  5. Superconductivity in Ca-doped graphene laminates

    NASA Astrophysics Data System (ADS)

    Chapman, J.; Su, Y.; Howard, C. A.; Kundys, D.; Grigorenko, A. N.; Guinea, F.; Geim, A. K.; Grigorieva, I. V.; Nair, R. R.

    2016-03-01

    Despite graphene’s long list of exceptional electronic properties and many theoretical predictions regarding the possibility of superconductivity in graphene, its direct and unambiguous experimental observation has not been achieved. We searched for superconductivity in weakly interacting, metal decorated graphene crystals assembled into so-called graphene laminates, consisting of well separated and electronically decoupled graphene crystallites. We report robust superconductivity in all Ca-doped graphene laminates. They become superconducting at temperatures (Tc) between ≈4 and ≈6 K, with Tc’s strongly dependent on the confinement of the Ca layer and the induced charge carrier concentration in graphene. We find that Ca is the only dopant that induces superconductivity in graphene laminates above 1.8 K among several dopants used in our experiments, such as potassium, caesium and lithium. By revealing the tunability of the superconducting response through doping and confinement of the metal layer, our work shows that achieving superconductivity in free-standing, metal decorated monolayer graphene is conditional on an optimum confinement of the metal layer and sufficient doping, thereby bringing its experimental realization within grasp.

  6. Laminate articles on biaxially textured metal substrates

    DOEpatents

    Beach, David B.; Morrell, Jonathan S.; Paranthaman, Mariappan; Chirayil, Thomas; Specht, Eliot D.; Goyal, Amit

    2003-12-16

    A laminate article comprises a substrate and a biaxially textured (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer over the substrate, wherein 0laminate article can include a layer of YBCO over the (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer. A layer of CeO.sub.2 between the YBCO layer and the (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer can also be include. Further included can be a layer of YSZ between the CeO.sub.2 layer and the (R.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer. The substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  7. Superconductivity in Ca-doped graphene laminates

    PubMed Central

    Chapman, J.; Su, Y.; Howard, C. A.; Kundys, D.; Grigorenko, A. N.; Guinea, F.; Geim, A. K.; Grigorieva, I. V.; Nair, R. R.

    2016-01-01

    Despite graphene’s long list of exceptional electronic properties and many theoretical predictions regarding the possibility of superconductivity in graphene, its direct and unambiguous experimental observation has not been achieved. We searched for superconductivity in weakly interacting, metal decorated graphene crystals assembled into so-called graphene laminates, consisting of well separated and electronically decoupled graphene crystallites. We report robust superconductivity in all Ca-doped graphene laminates. They become superconducting at temperatures (Tc) between ≈4 and ≈6 K, with Tc’s strongly dependent on the confinement of the Ca layer and the induced charge carrier concentration in graphene. We find that Ca is the only dopant that induces superconductivity in graphene laminates above 1.8 K among several dopants used in our experiments, such as potassium, caesium and lithium. By revealing the tunability of the superconducting response through doping and confinement of the metal layer, our work shows that achieving superconductivity in free-standing, metal decorated monolayer graphene is conditional on an optimum confinement of the metal layer and sufficient doping, thereby bringing its experimental realization within grasp. PMID:26979564

  8. Characteristics of laminates with delamination control strips

    SciTech Connect

    Sun, C.T.; Goering, J.C.; Alper, J.M.; Gause, L.W.

    1992-09-01

    Tough resin is needed to resist delamination crack propagation. However, modulus often has to be compromised because it is difficult to retain both high modulus and toughness in a matrix material. A potential solution is to use a hybrid system in which tough resin strips are included within a conventional matrix composite. By adjusting the spacing of the tough resin strips, maximum delamination size can be controlled. Experimental results for impact damage and subsequent damage propagation in laminates containing tough resin strips are reported. Plain adhesive strips and fiber-reinforced tough resin composite strips were used in constructing the hybrid laminates. Test results indicated that size of delamination inflicted by impact was confined between the tough resin strips. As a result, significantly increased residual compressive strength was obtained. Impacted laminates containing tough resin strips were also fatigue tested. It was found that these strips reduced the growth of the impact damage area relative to the growth seen in coupons with no tough resin strips. Damage growth from an open hole under tension fatigue was evaluated using both tough resin strips and glass fiber reinforced tough resin strips. Unreinforced tough resin strips retarded delamination growth from the open hole, but did not stop matrix cracks growing in the fiber direction. Fiber reinforced tough resin strips did not contain axial delamination growth from the open hole. However, they did act as crack arresters, stopping the through-the-thickness tension crack originating from the hole.

  9. Superconductivity in Ca-doped graphene laminates.

    PubMed

    Chapman, J; Su, Y; Howard, C A; Kundys, D; Grigorenko, A N; Guinea, F; Geim, A K; Grigorieva, I V; Nair, R R

    2016-01-01

    Despite graphene's long list of exceptional electronic properties and many theoretical predictions regarding the possibility of superconductivity in graphene, its direct and unambiguous experimental observation has not been achieved. We searched for superconductivity in weakly interacting, metal decorated graphene crystals assembled into so-called graphene laminates, consisting of well separated and electronically decoupled graphene crystallites. We report robust superconductivity in all Ca-doped graphene laminates. They become superconducting at temperatures (Tc) between ≈4 and ≈6 K, with Tc's strongly dependent on the confinement of the Ca layer and the induced charge carrier concentration in graphene. We find that Ca is the only dopant that induces superconductivity in graphene laminates above 1.8 K among several dopants used in our experiments, such as potassium, caesium and lithium. By revealing the tunability of the superconducting response through doping and confinement of the metal layer, our work shows that achieving superconductivity in free-standing, metal decorated monolayer graphene is conditional on an optimum confinement of the metal layer and sufficient doping, thereby bringing its experimental realization within grasp. PMID:26979564

  10. The tail domain of lamin B1 is more strongly modulated by divalent cations than lamin A

    PubMed Central

    Ganesh, Sairaam; Qin, Zhao; Spagnol, Stephen T; Biegler, Matthew T; Coffey, Kelli A; Kalinowski, Agnieszka; Buehler, Markus J; Dahl, Kris Noel

    2015-01-01

    The nucleoskeleton contains mainly nuclear intermediate filaments made of lamin proteins. Lamins provide nuclear structure and also play a role in various nuclear processes including signal transduction, transcription regulation and chromatin organization. The disparate functions of lamins may be related to the intrinsic disorder of the tail domains, which allows for altered and promiscuous binding. Here, we show modulation of lamin tail domain structures in the presence of divalent cations. We utilize changes in fluorescence of tryptophan residues within the Ig-fold flanked by disordered regions to experimentally measure protein thermodynamics. Using spectroscopy experiments and molecular dynamics simulations, we show that the tail domain of lamin B1 shows enhanced association with both Ca2+ and Mg2+ compared to the tail domain of lamin A. Binding curves show a similar KD between protein and ion (250–300 μM) for both proteins with both ions. However, we observe a maximum binding of ions to lamin B1 tail domain which is 2–3 times greater than that for lamin A tail domain by both experiment and simulation. Using simulations, we show that divalent ion association alters the Ig-fold by pinning flanking regions. With cells in culture, we observe altered lamin B1 organization in the presence of excess Mg2+ more so than for lamin A. We suggest that the differential sensitivity to divalent cations contributes to the vastly different functionalities and binding of the 2 proteins. PMID:25807068

  11. Lamin A is not synthesized as a larger precursor polypeptide.

    PubMed

    Lebel, S; Raymond, Y

    1987-12-16

    Isolation of rat liver nuclei in the presence of N-ethylmaleimide (NEM) led to the recovery in the final nuclear matrix of a higher molecular weight form of lamin A. The 2 kDa larger form was identified as lamin A by isoelectric point determination, recognition by an anti-lamin A and C monoclonal antibody and peptide mapping using V8 protease and N-chlorosuccinimide. The 2 kDa extension was tentatively localized to the carboxy-terminus of lamin A. Pulse-chase labeling and immunoprecipitation studies using baby hamster kidney cells showed that lysis of the cells in the presence of NEM allowed the recovery of a stable higher molecular weight form of lamin A. We conclude from these results that NEM prevented the degradation of the native form of lamin A previously thought to represent a higher molecular weight transient precursor form. PMID:3426582

  12. Homogenized Creep Behavior of CFRP Laminates at High Temperature

    NASA Astrophysics Data System (ADS)

    Fukuta, Y.; Matsuda, T.; Kawai, M.

    In this study, creep behavior of a CFRP laminate subjected to a constant stress is analyzed based on the time-dependent homogenization theory developed by the present authors. The laminate is a unidirectional carbon fiber/epoxy laminate T800H/#3631 manufactured by Toray Industries, Inc. Two kinds of creep analyses are performed. First, 45° off-axis creep deformation of the laminate at high temperature (100°C) is analyzed with three kinds of creep stress levels, respectively. It is shown that the present theory accurately predicts macroscopic creep behavior of the unidirectional CFRP laminate observed in experiments. Then, high temperature creep deformations at a constant creep stress are simulated with seven kinds of off-axis angles, i.e., θ = 0°, 10°, 30°, 45°, 60°, 75°, 90°. It is shown that the laminate has marked in-plane anisotropy with respect to the creep behavior.

  13. Phosphorylation of lamins determine their structural properties and signaling functions

    PubMed Central

    Torvaldson, Elin; Kochin, Vitaly; Eriksson, John E

    2015-01-01

    Lamin A/C is part of the nuclear lamina, a meshwork of intermediate filaments underlying the inner nuclear membrane. The lamin network is anchoring a complex set of structural and linker proteins and is either directly or through partner proteins also associated or interacting with a number of signaling protein and transcription factors. During mitosis the nuclear lamina is dissociated by well established phosphorylation- dependent mechanisms. A-type lamins are, however, also phosphorylated during interphase. A recent study identified 20 interphase phosphorylation sites on lamin A/C and explored their functions related to lamin dynamics; movements, localization and solubility. Here we discuss these findings in the light of lamin functions in health and disease. PMID:25793944

  14. Processing and mechanical characterization of alumina laminates

    NASA Astrophysics Data System (ADS)

    Montgomery, John K.

    2002-08-01

    Single-phase ceramics that combine property gradients or steps in monolithic bodies are sought as alternatives to ceramic composites made of dissimilar materials. This work describes novel processing methods to produce stepped-density (or laminated) alumina single-phase bodies that maintain their mechanical integrity. One arrangement consists of a stiff, dense bulk material with a thin, flaw tolerant, porous exterior layer. Another configuration consists of a lightweight, low-density bulk material with a thin, hard, wear resistant exterior layer. Alumina laminates with strong interfaces have been successfully produced in this work using two different direct-casting processes. Gelcasting is a useful near-net shape processing technique that has been combined with several techniques, such as reaction bonding of aluminum oxide and the use of starch as a fugative filler, to successfully produced stepped-density alumina laminates. The other direct casting process that has been developed in this work is thermoreversible gelcasting (TRG). This is a reversible gelation process that has been used to produce near-net shape dense ceramic bodies. Also, individual layers can be stacked together and heated to produce laminates. Bilayer laminate samples were produced with varied thickness of porous and dense layers. It was shown that due to the difference in modulus and hardness, transverse cracking is found upon Hertzian contact when the dense layer is on the exterior. In the opposite arrangement, compacted damage zones formed in the porous material and no damage occurred in the underlying dense layer. Flaw tolerant behavior of the porous exterior/dense underlayer was examined by measuring biaxial strength as a function of Vickers indentation load. It was found that the thinnest layer of porous material results in the greatest flaw tolerance. Also, higher strength was exhibited at large indentation loads when compared to dense monoliths. The calculated stresses on the surfaces

  15. A peculiar lamin in a peculiar mammal: Expression of lamin LIII in platypus (Ornithorhynchus anatinus).

    PubMed

    Peter, Annette; Khandekar, Shaunak; Deakin, Janine E; Stick, Reimer

    2015-11-01

    Platypus (Ornithorhynchus anatinus) holds a unique phylogenetic position at the base of the mammalian lineage due to an amalgamation of mammalian and sauropsid-like features. Here we describe the set of four lamin genes for platypus. Lamins are major components of the nuclear lamina, which constitutes a main component of the nucleoskeleton and is involved in a wide range of nuclear functions. Vertebrate evolution was accompanied by an increase in the number of lamin genes from a single gene in their closest relatives, the tunicates and cephalochordates, to four genes in the vertebrate lineage. Of the four genes the LIII gene is characterized by the presence of two alternatively spliced CaaX-encoding exons. In amphibians and fish LIII is the major lamin protein in oocytes and early embryos. The LIII gene is conserved throughout the vertebrate lineage, with the notable exception of marsupials and placental mammals, which have lost the LIII gene. Here we show that platypus has retained an LIII gene, albeit with a significantly altered structure and with a radically different expression pattern. The platypus LIII gene contains only a single CaaX-encoding exon and the head domain together with coil 1a and part of coil1b of the platypus LIII protein is replaced by a novel short non-helical N-terminus. It is expressed exclusively in the testis. These features resemble those of male germ cell-specific lamins in placental mammals, in particular those of lamin C2. Our data suggest (i) that the specific functions of LIII, which it fulfills in all other vertebrates, is no longer required in mammals and (ii) once it had been freed from these functions has undergone structural alterations and has adopted a new functionality in monotremes. PMID:26213206

  16. Fracture behavior of thick, laminated graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Harris, C. E.; Morris, D. H.

    1984-01-01

    The effect of laminate thickness on the fracture behavior of laminated graphite epoxy (T300/5208) composites was studied. The predominantly experimental research program included the study of the 0/+ or - 45/90 sub ns and 0/90 sub ns laminates with thickness of 8, 32, 64, 96 and 120 plies and the 0/+ or - 45 sub ns laminate with thickness of 6, 30, 60, 90 and 120 plies. The research concentrated on the measurement of fracture toughness utilizing the center-cracked tension, compact tension and three point bend specimen configurations. The development of subcritical damage at the crack tip was studied nondestructively using enhanced X-ray radiography and destructively using the laminate deply technique. The test results showed fracture toughness to be a function of laminate thickness. The fracture toughness of the 0 + or - 45/90 sub ns and 0/90 sub ns laminates decreased with increasing thickness and asymptotically approached lower bound values of 30 ksi square root of in. (1043 MPa square root of mm and 25 ksi square root of in (869 MPa square root of mm respectively. In contrast to the other two laminates, the fracture toughness of the 0/+ or - 45 sub ns laminate increased sharply with increasing thickness but reached an upper plateau value of 40 ksi square root of in (1390 MPa square root of mm) at 30 plies. Fracture toughness was independent of crack size for both thin and thick laminates for all three laminate types except for the 0/90 sub 2s laminate which spilt extensively. The center cracked tension, three point bend and compact tension specimens gave comparable results.

  17. Energy Saving Glass Lamination via Selective Radio-Frequency Heating

    SciTech Connect

    Shulman, Holly S.; Allan, Shawn M.

    2009-11-11

    This Inventions and Innovations program supported the technical and commercial research and development needed to elevate Ceralink's energy saving process for flat glass lamination from bench scale to a self-supporting technology with significant potential for growth. Radio-frequency heating was any un-explored option for laminating glass prior to this program. With significant commercial success through time and energy savings in the wood, paper, and plastics industries, RF heating was found to have significant promise for the energy intensive glass lamination industry. A major technical goal of the program was to demonstrate RF lamination across a wide range of laminate sizes and materials. This was successfully accomplished, dispelling many skeptics' concerns about the abilities of the technology. Ceralink laminated panels up to 2 ft x 3 ft, with four sets processed simultaneously, in a 3 minute cycle. All major categories of interlayer materials were found to work with RF lamination. In addition to laminating glass, other materials including photovoltaic silicon solar cells, light emitting diodes, metallized glass, plastics (acrylic and polycarbonate), and ceramics (alumina) were found compatible with the RF process. This opens up a wide range of commercial opportunities beyond the initially targeted automotive industry. The dramatic energy savings reported for RF lamination at the bench scale were found to be maintained through the scale up of the process. Even at 2 ft x 3 ft panel sizes, energy savings are estimated to be at least 90% compared to autoclaving or vacuum lamination. With targeted promotion through conference presentations, press releases and internet presence, RF lamination has gained significant attention, drawing large audiences at American Ceramic Society meetings. The commercialization success of the project includes the establishment of a revenue-generating business model for providing process development and demonstrations for potential RF

  18. Tension fatigue analysis and life prediction for composite laminates

    NASA Technical Reports Server (NTRS)

    O'Brien, T. K.; Rigamonti, M.; Zanotti, C.

    1989-01-01

    A methodology is presented for the tension fatigue analysis and life prediction of composite laminates subjected to tension fatigue loading. The methodology incorporates both the generic fracture mechanics characterization of delamination and the assessment of the infuence of damage on laminate fatigue life. Tension fatigue tests were conducted on quasi-isotropic and orthotropic glass epoxy, graphite epoxy, and glass/graphite epoxy hybrid laminates, demonstrating good agreement between measured and predicted lives.

  19. A unified theory for laminated plates

    NASA Astrophysics Data System (ADS)

    Guiamatsia Tafeuvoukeng, Irene

    A literature survey on plate and beam theories show how the advent of the finite element method and the variational method circa 1940 have been a great stimulant for the research in this field. The initial thin plate formulation has been incrementally expanded to treat the isotropic thick plate, the anisotropic single layer, and then laminated plates. It appears however that current formulations still fall into one of two categories: (1) The formulation is tailored for a specific laminate and/or loading case; (2) or the formulation is too complicated to be of practical relevance. In this work a new unifying approach to laminated plate formulation is presented. All laminated plates, including sandwich panels, subjected to any surface load and with any boundary conditions are treated within a single model. In addition, the fundamental behavior of the plate as a two-dimensional structural element is explained. The novel idea is the introduction of fundamental state solutions, which are analytical far field stress and strain solutions of the laminated plate subjected to a set of hierarchical primary loads, the fundamental loads. These loads are carefully selected to form a basis of the load space, and corresponding solutions are superposed to obtain extremely accurate predictions of the three dimensional solution. six,y,z =aklx,y sikl z where i = 1,..., 6; 1=1,...,l max is a substate of the kth fundamental state k=1,2,3,... Typically, a fundamental state solution is expressed as a through-thickness function (z), while the amplitudes of each fundamental load are found from two dimensional finite element solution as a function of in-plane coordinates (x,y). Three major contributions are produced in this work: (1) A complete calibration of the plate as a two-dimensional structure is performed with pure bending and constant shear fundamental states. (2) There are four independent ways to apply a constant shear resultant on a plate, as opposed to one for a beam. This makes

  20. Extrinsic fracture mechanisms in two laminated metal composites

    SciTech Connect

    Lesuer, D.; Syn, C.; Riddle, R.; Sherby, O.

    1994-11-29

    The crack growth behavior and fracture toughness of two laminated metal composites (6090/SiC/25p laminated with 5182 and ultrahigh-carbon steel laminated with brass) have been studied in both ``crack arrester`` and ``crack divider`` orientations. The mechanisms of crack growth were analyzed and extrinsic toughening mechanisms were found to contribute significantly to the toughness. The influence of laminate architecture (layer thickness and component volume function), component material properties and residual stress on these mechanisms and the resulting crack growth resistance are discussed.

  1. Residual stress and crack propagation in laminated composites

    SciTech Connect

    Yttergren, R.M.F.; Zeng, K.; Rowcliffe, D.J.

    1994-12-31

    Residual stress distributions in several laminated ceramic composites were measured by an indentation technique. The material included alumina-zirconia laminated composites, containing strong interfaces, and alumina-porcelain laminated composites with both weak and strong interfaces. The residual stress in these material originates from the mismatch of the thermal properties, differences in elastic properties, and different shrinkage of the laminates during sintering. An experimental technique is presented which gives a direct view of the residual stress state in the materials. Values of residual tensile stress are presented as a function of position relative to the interface in each material.

  2. Cured shape prediction of the bistable hybrid composite laminate

    NASA Astrophysics Data System (ADS)

    Dai, Fu-hong; Zhang, Bo-ming; Du, Shan-yi

    2009-07-01

    A bistable unsymmetric hybrid composite laminate with quite high stiffness and large shape change is presented. Rayleigh-Ritz method is used to predict the cured shape and the predited results agree well with the experimentals. The critical loads switching between different shapes are tested. It shows that the critical load for hybrid composite laminates increases greatly (up to 10 times) compared with the pure fiber reinforced polymer matrix composite laminates. The influence of different geometric and material properites on the bistable shape is discussed. It reveals that the present hybrid bistable laminate is more designable and miscellaneous.

  3. Lamins position the nuclear pores and centrosomes by modulating dynein

    PubMed Central

    Guo, Yuxuan; Zheng, Yixian

    2015-01-01

    Lamins, the type V nuclear intermediate filament proteins, are reported to function in both interphase and mitosis. For example, lamin deletion in various cell types can lead to an uneven distribution of the nuclear pore complexes (NPCs) in the interphase nuclear envelope, whereas deletion of B-type lamins results in spindle orientation defects in mitotic neural progenitor cells. How lamins regulate these functions is unknown. Using mouse cells deleted of different combinations or all lamins, we show that lamins are required to prevent the aggregation of NPCs in the nuclear envelope near centrosomes in late G2 and prophase. This asymmetric NPC distribution in the absence of lamins is caused by dynein forces acting on NPCs via the dynein adaptor BICD2. We further show that asymmetric NPC distribution upon lamin depletion disrupts the distribution of BICD2 and p150 dynactin on the nuclear envelope at prophase, which results in inefficient dynein-driven centrosome separation during prophase. Therefore lamins regulate microtubule-based motor forces in vivo to ensure proper NPC distribution in interphase and centrosome separation in the mitotic prophase. PMID:26246603

  4. Sound transmission into a laminated composite cylindrical shell

    NASA Technical Reports Server (NTRS)

    Koval, L. R.

    1980-01-01

    In the context of the transmission of airborne noise into an aircraft fuselage, a mathematical model is presented for the transmission of an oblique plane sound wave into a laminated composite circular cylindrical shell. Numerical results are obtained for geometry typical of a narrow-bodied jet transport. Results indicate that from the viewpoint of noise attenuation on laminated composite shell does not appear to offer any significant advantage over an aluminum shell. However, the transmission loss of a laminated composite shell is sensitive to the orientation of the fibers and this suggests the possibility of using a laminated composite shell to tailor the noise attenuation characteristics to meet a specific need.

  5. Impact damage resistance of thin stitched carbon/epoxy laminates

    NASA Astrophysics Data System (ADS)

    Francesconi, L.; Aymerich, F.

    2015-07-01

    The study examines the influence of through-thickness stitching on the damage response of thin cross-ply carbon/epoxy laminates subjected to low-velocity impacts. Instrumented impact tests were carried out on unstitched and polyethylene stitched laminates and the resulting damage was assessed in detail by X-radiography analyses. The results of the observations carried out during the experimental analyses are illustrated and discussed to identify the mechanical role played by through-thickness reinforcement and to highlight the influence of the laminate layup on the impact resistance of stitched laminates.

  6. Mapping of lamin A- and progerin-interacting genome regions.

    PubMed

    Kubben, Nard; Adriaens, Michiel; Meuleman, Wouter; Voncken, Jan Willem; van Steensel, Bas; Misteli, Tom

    2012-10-01

    Mutations in the A-type lamins A and C, two major components of the nuclear lamina, cause a large group of phenotypically diverse diseases collectively referred to as laminopathies. These conditions often involve defects in chromatin organization. However, it is unclear whether A-type lamins interact with chromatin in vivo and whether aberrant chromatin-lamin interactions contribute to disease. Here, we have used an unbiased approach to comparatively map genome-wide interactions of gene promoters with lamin A and progerin, the mutated lamin A isoform responsible for the premature aging disorder Hutchinson-Gilford progeria syndrome (HGPS) in mouse cardiac myoytes and embryonic fibroblasts. We find that lamin A-associated genes are predominantly transcriptionally silent and that loss of lamin association leads to the relocation of peripherally localized genes, but not necessarily to their activation. We demonstrate that progerin induces global changes in chromatin organization by enhancing interactions with a specific subset of genes in addition to the identified lamin A-associated genes. These observations demonstrate disease-related changes in higher order genome organization in HGPS and provide novel insights into the role of lamin-chromatin interactions in chromatin organization. PMID:22610065

  7. The Displacement Perspective During Ultimate Failure of Composite Laminates

    NASA Astrophysics Data System (ADS)

    Pal, P.; Bhar, A.

    2013-04-01

    This paper deals with the studies on the state of displacement of symmetric and anti-symmetric angle-ply and cross-ply laminated composite plates during its ultimate failure, subjected to transverse static load. First-order shear deformation theory (FSDT) is employed in conjunction with the finite element approach using eight-noded quadratic isoparametric element. The free vibration analyses of isotropic and laminated composite plates are carried out to ensure the overall validity of the present finite element formulation. The mid surface of the laminate is considered as the reference plane. The principal material directions in different laminae are oriented to produce a laminated structural element capable of resisting loads in several directions. The stiffness of a composite laminate is obtained from the properties of the constituent laminae. The affected stiffness of the failed lamina is discarded completely after the failure of weakest ply. The rigidity matrix of the laminate with remaining laminae is re-established. The re-evaluation process continues until the laminate fails completely. To investigate the displacement behaviour of laminates during the ultimate failure, parametric studies are carried out for different cases by varying the stacking sequences, fiber orientations, layer thicknesses, aspect ratios and the number of layers in the laminate. The comparison of results in terms of non-dimensional natural frequencies and ply-by-ply failure analyses obtained from the present investigation are made with those available in the reported literature.

  8. Mechanical model of blebbing in nuclear lamin meshworks

    PubMed Central

    Funkhouser, Chloe M.; Sknepnek, Rastko; Shimi, Takeshi; Goldman, Anne E.; Goldman, Robert D.; Olvera de la Cruz, Monica

    2013-01-01

    Much of the structural stability of the nucleus comes from meshworks of intermediate filament proteins known as lamins forming the inner layer of the nuclear envelope called the nuclear lamina. These lamin meshworks additionally play a role in gene expression. Abnormalities in nuclear shape are associated with a variety of pathologies, including some forms of cancer and Hutchinson–Gilford Progeria Syndrome, and often include protruding structures termed nuclear blebs. These nuclear blebs are thought to be related to pathological gene expression; however, little is known about how and why blebs form. We have developed a minimal continuum elastic model of a lamin meshwork that we use to investigate which aspects of the meshwork could be responsible for bleb formation. Mammalian lamin meshworks consist of two types of lamin proteins, A type and B type, and it has been reported that nuclear blebs are enriched in A-type lamins. Our model treats each lamin type separately and thus, can assign them different properties. Nuclear blebs have been reported to be located in regions where the fibers in the lamin meshwork have a greater separation, and we find that this greater separation of fibers is an essential characteristic for generating nuclear blebs. The model produces structures with comparable morphologies and distributions of lamin types as real pathological nuclei. Thus, preventing this opening of the meshwork could be a route to prevent bleb formation, which could be used as a potential therapy for the pathologies associated with nuclear blebs. PMID:23401537

  9. 78 FR 48903 - Certain Products Having Laminated Packaging, Laminated Packaging, and Components Thereof...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-12

    ... infringement of certain claims of nine patents. 78 FR 19,007. The subject products are certain laminated... industry requirement.'' 78 FR 19,008. The ALJ conducted a hearing on the domestic-industry issue on May 16... the complainant did not satisfy the economic prong of the domestic industry requirement. On...

  10. Laminated anisotropic reinforced plastic plates and shells

    NASA Technical Reports Server (NTRS)

    Korolev, V. I.

    1981-01-01

    Basic technical theories and engineering calculation equations for anisotropic plates and shells made of rigid reinforced plastics, mainly laminated fiberglass, are presented and discussed. Solutions are given for many problems of design of structural plates and shells, including curved sections and tanks, as well as two chapters on selection of the optimum materials, are given. Accounting for interlayer shearing and transverse separation, which are new engineering properties, are discussed. Application of the results obtained to thin three ply plates and shells wth a light elastic filler is presented and discussed.

  11. Micromechanics of composite laminate compression failures

    NASA Technical Reports Server (NTRS)

    Guynn, E. Gail; Bradley, Walter L.

    1988-01-01

    The purpose of this annual progress report is to summarize the work effort and results accomplished from July 1987 through July 1988 on NASA Research Grant NAG1-659 entitled Micromechanics of Composite Laminate Compressive Failure. The report contains: (1) the objective of the proposed research, (2) the summary of accomplishments, (3) a more extensive review of compression literature, (4) the planned material (and corresponding properties) received to date, (5) the results for three possible specimen geometries, experimental procedures planned, and current status of the experiments, and (6) the work planned for the next contract year.

  12. Strength of composite laminates under biaxial loads

    NASA Astrophysics Data System (ADS)

    Hinton, M. J.; Soden, P. D.; Kaddour, A. S.

    1996-05-01

    Five well known failure criteria and one simple progressive model have been used in conjunction with laminate theory, which allows for nonlinear lamina shear behaviour, to predict the initial and final failure strengths of filament wound composite tubes. The predictions have been compared with experimental leakage and fracture stresses for ±75°, ±55° and ±45° filament wound GRP tubes subjected to a wide range of biaxial stress systems including biaxial compression. In some cases the fracture strengths were a factor of 10 higher than the initial failure predictions. The simple progressive failure theory predictions gave the best agreement with the experimental results.

  13. Long-lasting FR-4 surface hydrophilisation towards commercial PCB passive microfluidics

    NASA Astrophysics Data System (ADS)

    Vasilakis, Nikolaos; Moschou, Despina; Carta, Daniela; Morgan, Hywel; Prodromakis, Themistoklis

    2016-04-01

    Printed circuit boards (PCB) technologies are an attractive system for simple sensing and microfluidic systems. Controlling the surface properties of PCB material is an important part of this technology and to date there has been no study on long-term hydrophilisation stability of these materials. In this work, the effect of different oxygen plasma input power and treatment duration times on the wetting properties of FR-4 surfaces was investigated by sessile droplet contact angle measurements. Super and weakly hydrophilic behaviour was achieved and the retention time of these properties was studied, with the hydrophilic nature being retained for at least 26 days. To demonstrate the applicability of this treatment method, a commercially manufactured microfluidic structure made from a multilayer PCB (3-layer FR-4 stack) was exposed to oxygen plasma at the optimum conditions. The structures could be filled with deionised (DI) water under capillary flow unlike the virgin devices.

  14. Hole-thru-laminate mounting supports for photovoltaic modules

    SciTech Connect

    Wexler, Jason; Botkin, Jonathan; Culligan, Matthew; Detrick, Adam

    2015-02-17

    A mounting support for a photovoltaic module is described. The mounting support includes a pedestal having a surface adaptable to receive a flat side of a photovoltaic module laminate. A hole is disposed in the pedestal, the hole adaptable to receive a bolt or a pin used to couple the pedestal to the flat side of the photovoltaic module laminate.

  15. Stress concentration factors around a circular hole in laminated composites

    NASA Technical Reports Server (NTRS)

    Ueng, C. E. S.

    1976-01-01

    Stress concentration factors around a circular hole in a composite laminate are determined. The specific case investigated is a four layer (-45/45/45/-45 degs) graphite epoxy laminate. The factors are determined experimentally by means of electrical resistance strain gages, and analytically by using a hybrid finite element analysis.

  16. A MEMS lamination technology based on sequential multilayer electrodeposition

    SciTech Connect

    Kim, M; Kim, J; Herrault, F; Schafer, R; Allen, MG

    2013-08-06

    A MEMS lamination technology based on sequential multilayer electrodeposition is presented. The process comprises three main steps: (1) automated sequential electrodeposition of permalloy (Ni80Fe20) structural and copper sacrificial layers to form multilayer structures of significant total thickness; (2) fabrication of polymeric anchor structures through the thickness of the multilayer structures and (3) selective removal of copper. The resulting structure is a set of air-insulated permalloy laminations, the separation of which is sustained by insulating polymeric anchor structures. Individual laminations have precisely controllable thicknesses ranging from 500 nm to 5 mu m, and each lamination layer is electrically isolated from adjacent layers by narrow air gaps of similar scale. In addition to air, interlamination insulators based on polymers are investigated. Interlamination air gaps with very high aspect ratio (>1:100) can be filled with polyvinylalcohol and polydimethylsiloxane. The laminated structures are characterized using scanning electron microscopy and atomic force microscopy to directly examine properties such as the roughness and the thickness uniformity of the layers. In addition, the quality of the electrical insulation between the laminations is evaluated by quantifying the eddy current within the sample as a function of frequency. Fabricated laminations are comprised of uniform, smooth (surface roughness < 100 nm) layers with effective electrical insulation for all layer thicknesses and insulator approaches studied. Such highly laminated structures have potential uses ranging from energy conversion to applications where composite materials with highly anisotropic mechanical or thermal properties are required.

  17. Fabrication of Multi-Ply Birefringent Fibrous Composite Laminates

    NASA Technical Reports Server (NTRS)

    Daniel, I.; Niiro, T.

    1984-01-01

    Fabrication method produces unidirectional, multi-ply, transparent birefringent fibrous composite laminates for use in macromechanical stress analysis conducted by means of anisotropic photoelasticity. New laminates glass-fiber-reinforced plastics for which matrix and fibers have same index of refraction. Method utilized in structural applications of composites.

  18. Buckling of angle-ply laminated circular cylindrical shells

    NASA Technical Reports Server (NTRS)

    Hirano, Y.

    1979-01-01

    This note presents closed-form solutions for axisymmetrical and axially unsymmetrical buckling of angle-ply laminated circular cylindrical shells under axial compression. The axisymmetrical and axially unsymmetrical buckling stress are found to be different from each other, and the best lamination angles which give the highest buckling stress are obtained.

  19. Identification of differential protein interactors of lamin A and progerin.

    PubMed

    Kubben, Nard; Voncken, Jan Willem; Demmers, Jeroen; Calis, Chantal; van Almen, Geert; Pinto, Yigal; Misteli, Tom

    2010-01-01

    The nuclear lamina is an interconnected meshwork of intermediate filament proteins underlying the nuclear envelope. The lamina is an important regulator of nuclear structural integrity as well as nuclear processes, including transcription, DNA replication and chromatin remodeling. The major components of the lamina are A- and B-type lamins. Mutations in lamins impair lamina functions and cause a set of highly tissue-specific diseases collectively referred to as laminopathies. The phenotypic diversity amongst laminopathies is hypothesized to be caused by mutations affecting specific protein interactions, possibly in a tissue-specific manner. Current technologies to identify interaction partners of lamin A and its mutants are hampered by the insoluble nature of lamina components. To overcome the limitations of current technologies, we developed and applied a novel, unbiased approach to identify lamin A-interacting proteins. This approach involves expression of the high-affinity OneSTrEP-tag, precipitation of lamin-protein complexes after reversible protein cross-linking and subsequent protein identification by mass spectrometry. We used this approach to identify in mouse embryonic fibroblasts and cardiac myocyte NklTAg cell lines proteins that interact with lamin A and its mutant isoform progerin, which causes the premature aging disorder Hutchinson-Gilford progeria syndrome (HGPS). We identified a total of 313 lamina-interacting proteins, including several novel lamin A interactors, and we characterize a set of 35 proteins which preferentially interact with lamin A or progerin. PMID:21327095

  20. Self-heating forecasting for thick laminate specimens in fatigue

    NASA Astrophysics Data System (ADS)

    Lahuerta, F.; Westphal, T.; Nijssen, R. P. L.

    2014-12-01

    Thick laminate sections can be found from the tip to the root in most common wind turbine blade designs. Obtaining accurate and reliable design data for thick laminates is subject of investigations, which include experiments on thick laminate coupons. Due to the poor thermal conductivity properties of composites and the material self-heating that occurs during the fatigue loading, high temperature gradients may appear through the laminate thickness. In the case of thick laminates in high load regimes, the core temperature might influence the mechanical properties, leading to premature failures. In the present work a method to forecast the self-heating of thick laminates in fatigue loading is presented. The mechanical loading is related with the laminate self-heating, via the cyclic strain energy and the energy loss ratio. Based on this internal volumetric heat load a thermal model is built and solved to obtain the temperature distribution in the transient state. Based on experimental measurements of the energy loss factor for 10mm thick coupons, the method is described and the resulting predictions are compared with experimental surface temperature measurements on 10 and 30mm UD thick laminate specimens.

  1. A Laminated Track for the Inductrack System: Theory and Experiment

    SciTech Connect

    Post, R F; Hoburg, J F

    2004-01-12

    A laminated structure, composed of stacks of thin conducting sheets, has several advantages over a litz-wire ladder as the ''track'' wherein levitating currents are induced by a permanent magnet array on a moving vehicle. Modeling and experimental results for the laminated track are described and evaluated in this paper.

  2. Better Thermal Insulation in Solar-Array Laminators

    NASA Technical Reports Server (NTRS)

    Burger, D. R.; Knox, J. F.

    1984-01-01

    Glass marbles improve temperature control. Modified vacuum laminator for photovoltaic solar arrays includes thermal insulation made of conventional glass marbles. Marbles serve as insulation for temperature control of lamination process at cure temperatures as high as 350 degrees F. Used to replace original insulation made of asbestos cement.

  3. Near-threshold fatigue crack growth in aluminum composite laminates

    SciTech Connect

    Hoffman, P.B.; Gibeling, J.C.

    1995-03-15

    One promising method for improving the mechanical properties of particulate MMCs is to laminate the brittle composite with a more ductile component. A system currently being developed at Lawrence Livermore National Laboratory (LLNL) is a multilayer laminate consisting of alternating layers of AA6090/SiC/25p and more ductile AA5182. In order to further examine the effects of lamination on fatigue crack propagation mechanics and mechanisms, the fatigue crack growth behavior of the aluminum composite laminate developed at LLNL was examined. The laminate and the AA6090/SiC/25p component were studied in the T6 heat treatment condition for subsequent comparison. Fatigue crack surfaces were examined using scanning electron microscopy for further insight into crack growth mechanisms.

  4. The strength of laminated composite materials under repeated impact loading

    NASA Technical Reports Server (NTRS)

    Rotem, Assa

    1988-01-01

    When low velocity and energy impact is exerted on a laminated composite material, in a perpendicular direction to the plane of the laminate, invisible damage may develop. It is shown analytically and experimentally that the invisible damage occurs during the first stage of contact between the impactor and the laminate and is a result of the contact stresses. However, the residual flexural strength changes only slightly, because it depends mainly on the outer layers, and these remain undamaged. Repeated impact intensifies the damage inside the laminate and causes larger bending under equivalent impact load. Finally, when the damage is most severe, even though it is still invisible, the laminate fails because of bending on the tension side. If the repeated impact is halted before final fracture occurs the residual strength and modulus would decrease by a certain amount.

  5. Deposition of laminated shale: A field and experimental study

    NASA Astrophysics Data System (ADS)

    Carey, Daniel L.; Roy, David C.

    1985-03-01

    Intermittently laminated shale of the Jemtland Formation in Maine is characterized by thin lenticular silt segregations interlaced with argillaceous and organic material (including graptolites). This shale is thinly interbedded with nonlaminated shale, siltstone, and thicker turbidite graywacke beds. Experiments suggest that the intermittently laminated shale was deposited by silt/clay-laden currents and may have been part of an upward turbidite progression from parallel-laminated silt (>60% silt), through intermittently laminated mud (40 to 60% silt), to nonlaminated mud (20 to 40% silt). Intermittently laminated mud may be produced from silt/clay flows that are: decelerating at a constant silt content, losing silt at constant velocity; or both decelerating and losing silt.

  6. Matrix cracking in laminated composites under monotonic and cyclic loadings

    NASA Technical Reports Server (NTRS)

    Allen, David H.; Lee, Jong-Won

    1991-01-01

    An analytical model based on the internal state variable (ISV) concept and the strain energy method is proposed for characterizing the monotonic and cyclic response of laminated composites containing matrix cracks. A modified constitution is formulated for angle-ply laminates under general in-plane mechanical loading and constant temperature change. A monotonic matrix cracking criterion is developed for predicting the crack density in cross-ply laminates as a function of the applied laminate axial stress. An initial formulation for a cyclic matrix cracking criterion for cross-ply laminates is also discussed. For the monotonic loading case, a number of experimental data and well-known models are compared with the present study for validating the practical applicability of the ISV approach.

  7. Vibration suppression of composite laminated plate with nonlinear energy sink

    NASA Astrophysics Data System (ADS)

    Zhang, Ye-Wei; Zhang, Hao; Hou, Shuai; Xu, Ke-Fan; Chen, Li-Qun

    2016-06-01

    The composite laminated plate is widely used in supersonic aircraft. So, there are many researches about the vibration suppression of composite laminated plate. In this paper, nonlinear energy sink (NES) as an effective method to suppress vibration is studied. The coupled partial differential governing equations of the composite laminated plate with the nonlinear energy sink (NES) are established by using the Hamilton principle. The fourth-order Galerkin discrete method is used to truncate the partial differential equations, which are solved by numerical integration method. Meanwhile study about the precise effectiveness of the nonlinear energy sink (NES) by discussing the different installation location of the nonlinear energy sink (NES) at the same speed. The results indicate that the nonlinear energy sink (NES) can significantly suppress the severe vibration of the composite laminated plate with speed wind loadings in to protect the composite laminated plate from excessive vibration.

  8. Lamins as mediators of oxidative stress

    SciTech Connect

    Sieprath, Tom; Darwiche, Rabih; De Vos, Winnok H.

    2012-05-18

    Highlights: Black-Right-Pointing-Pointer The nuclear lamina defines structural and functional properties of the cell nucleus. Black-Right-Pointing-Pointer Lamina dysfunction leads to a broad spectrum of laminopathies. Black-Right-Pointing-Pointer Recent data is reviewed connecting laminopathies to oxidative stress. Black-Right-Pointing-Pointer A framework is proposed to explain interactions between lamins and oxidative stress. -- Abstract: The nuclear lamina defines both structural and functional properties of the eukaryotic cell nucleus. Mutations in the LMNA gene, encoding A-type lamins, lead to a broad spectrum of diseases termed laminopathies. While different hypotheses have been postulated to explain disease development, there is still no unified view on the mechanistic basis of laminopathies. Recent observations indicate that laminopathies are often accompanied by altered levels of reactive oxygen species and a higher susceptibility to oxidative stress at the cellular level. In this review, we highlight the role of reactive oxygen species for cell function and disease development in the context of laminopathies and present a framework of non-exclusive mechanisms to explain the reciprocal interactions between a dysfunctional lamina and altered redox homeostasis.

  9. Laminated ceramic components for microfluidic applications

    NASA Astrophysics Data System (ADS)

    Matson, Dean W.; Martin, Peter M.; Bennett, Wendy D.; Stewart, Donald C.; Bonham, Charles C.

    1999-08-01

    Applications for micro fluidic components continue to expand as the benefits resulting from the small volumes and light weight of such devices are recognized. Such benefits are particularly attractive for man-portable and automotive devices where reduction of weight is critical. As applications expand, so too does the need for the development of methods for producing micro fluidic components from unconventional materials (i.e., materials other than silicon). At the Pacific Northwest National Laboratory, we are currently developing processes for producing laminated multilevel ceramic components containing microchannel features that will find applications in micro fluidic chemical processing and energy management systems. Thin layers of green ceramic tape are patterned with micro fluidic flow features using one of a number of cutting processes. The patterned layers are then stacked and laminated with other layers of green tape, ceramic plate, or other materials using a series of processing steps. The resulting monolithic, leak-tight micro fluidic ceramic components are capable of tolerating high temperature or chemically corrosive environments. Fabrication issues associated with the use of the green ceramic tape for this type of application will be discussed, and examples of test components produced using these processes will be presented.

  10. Development of a heterogeneous laminating resin system

    NASA Technical Reports Server (NTRS)

    Biermann, T. F.; Hopper, L. C.

    1985-01-01

    The factors which effect the impact resistance of laminating resin systems and yet retain equivalent performance with the conventional 450 K curing epoxy matrix systems in other areas were studied. Formulation work was conducted on two systems, an all-epoxy and an epoxy/bismaleimide, to gain fundamental information on the effect formulation changes have upon neat resin and composite properties. The all-epoxy work involved formulations with various amounts and combinations of eight different epoxy resins, four different hardeners, fifteen different toughening agents, a filler, and a catalyst. The epoxy/bismaleimide effort improved formulations with various amounts and combinations of nine different resins, four different hardeners, eight different toughening agents, four different catalysts, and a filler. When a formulation appeared to offer the proper combination of properties required for a laminating resin Celion 3K-70P fabric was prepregged. Initial screening tests on composites primarily involved Gardner type impact and measurement of short beam shear strengths under dry and hot/wet conditions.

  11. Free Vibration of Uncertain Unsymmetrically Laminated Beams

    NASA Technical Reports Server (NTRS)

    Kapania, Rakesh K.; Goyal, Vijay K.

    2001-01-01

    Monte Carlo Simulation and Stochastic FEA are used to predict randomness in the free vibration response of thin unsymmetrically laminated beams. For the present study, it is assumed that randomness in the response is only caused by uncertainties in the ply orientations. The ply orientations may become random or uncertain during the manufacturing process. A new 16-dof beam element, based on the first-order shear deformation beam theory, is used to study the stochastic nature of the natural frequencies. Using variational principles, the element stiffness matrix and mass matrix are obtained through analytical integration. Using a random sequence a large data set is generated, containing possible random ply-orientations. This data is assumed to be symmetric. The stochastic-based finite element model for free vibrations predicts the relation between the randomness in fundamental natural frequencies and the randomness in ply-orientation. The sensitivity derivatives are calculated numerically through an exact formulation. The squared fundamental natural frequencies are expressed in terms of deterministic and probabilistic quantities, allowing to determine how sensitive they are to variations in ply angles. The predicted mean-valued fundamental natural frequency squared and the variance of the present model are in good agreement with Monte Carlo Simulation. Results, also, show that variations between plus or minus 5 degrees in ply-angles can affect free vibration response of unsymmetrically and symmetrically laminated beams.

  12. Hygrothermally stable laminated composites with optimal coupling

    NASA Astrophysics Data System (ADS)

    Haynes, Robert Andrew

    This work begins by establishing the necessary and sufficient conditions for hygrothermal stability of composite laminates. An investigation is performed into the range of coupling achievable from within all hygrothermally stable families. The minimum number of plies required to create an asymmetric hygrothermally stable stacking sequence is found to be five. Next, a rigorous and general approach for determining designs corresponding to optimal levels of coupling is established through the use of a constrained optimization procedure. Couplings investigated include extension-twist, bend-twist, extension-bend, shear-twist, and anticlastic. For extension-twist and bend-twist coupling, specimens from five- through ten-ply laminates are manufactured and tested to demonstrate hygrothermal stability and achievable levels of coupling. Nonlinear models and finite element analysis are developed, and predictions are verified through comparison with test results. Sensitivity analyses are performed to demonstrate the robustness of the hygrothermal stability and couplings to deviations in ply angle, typical of manufacturing tolerances. Comparisons are made with current state-of-the-art suboptimal layups, and significant increases in coupling over previously known levels are demonstrated.

  13. Bending analysis of laminated composite box beams

    SciTech Connect

    Tripathy, A.K.; Patel, H.J.; Pang, S.S. . Dept. of Mechanical Engineering)

    1994-01-01

    Box beams are widely used in weight reduction structures such as aircraft wings. The use of composite box beams further reduces the weight factor for such structures with the same deflection and stress as that of isotropic box beams. The difference in the behavior of composite box beam with different fiber orientation, number of plies, and number of stringers also provides a wide range of designing parameters to achieve the required performance for a given problem. A bending analysis has been carried out for the study of deflections and stresses for box beams of different material (isotropic and laminated composites), size, and number of stringers subjected to different kinds of loading conditions. A finite element model has been developed based on the strain energy principle, and the results are compared with an available commercial code COSMOS/M.'' Experiments using aluminum and scotchply composite laminates were conducted to verify the results. An optimal design for size and number of stiffeners for a given loading condition has been achieved. Investigations have also been carried out to find the effect of transverse shear on the span-wise normal stress.

  14. Geometrically nonlinear behavior of piezoelectric laminated plates

    NASA Astrophysics Data System (ADS)

    Rabinovitch, Oded

    2005-08-01

    The geometrically nonlinear behavior of piezo-laminated plates actuated with isotropic or anisotropic piezoelectric layers is analytically investigated. The analytical model is derived using the variational principle of virtual work along with the lamination and plate theories, the von Karman large displacement and moderate rotation kinematic relations, and the anisotropic piezoelectric constitutive laws. A solution strategy that combines the approach of the method of lines, the advantages of the finite element concept, and the variational formulation is developed. This approach yields a set of nonlinear ordinary differential equations with nonlinear boundary conditions, which are solved using the multiple-shooting method. Convergence and verification of the model are examined through comparison with linear and nonlinear results of other approximation methods. The nonlinear response of two active plate structures is investigated numerically. The first plate is actuated in bending using monolithic piezoceramic layers and the second one is actuated in twist using macro-fiber composites. The results quantitatively reveal the complicated in-plane stress state associated with the piezoelectric actuation and the geometrically nonlinear coupling of the in-plane and out-of-plane responses of the plate. The influence of the nonlinear effects ranges from significant stiffening in certain combinations of electrical loads and boundary conditions to amplifications of the induced deflections in others. The paper closes with a summary and conclusions.

  15. Magnetic sheet steel lamination detection, phase 1

    NASA Astrophysics Data System (ADS)

    Carignan, F. J.; Syniuta, W. D.

    1980-08-01

    Research to assess the feasibility of a nondestructive magnetic inspection technique for detecting defective sheet steel is reported. A major problem in the deep drawing and stamping industry is the failure of sheet steel due to laminations which occur when the steel is formed into various shapes or processed further. A continuous nondestructive testing method was developed based upon differences in magnetic properties of acceptable steel and defective steel. The technique assumes an increase in the magnetic hardness of the defect compared to the base material. Experimental results obtained with the artificial flaw demonstrate that it is possible to sense magnetic differences in sheet steel if the differences are large enough. However, as the differences in magnetic hardness diminish, or where thin surface defects or internal laminations occur, detection becomes increasingly difficult. Moreoever, it has not been established that all sheet steel defects are magnetically harder than unflawed material. It was concluded that the technique, which can detect only some flaws and is incapable of detecting many important defects, would be only marginally useful.

  16. Buckling analysis of laminated thin shells in a hot environment

    NASA Technical Reports Server (NTRS)

    Gotsis, Pascal K.; Guptil, James D.

    1993-01-01

    Results are presented of parametric studies to assess the effects of various parameters on the buckling behavior of angle-ply, laminated thin shells in a hot environment. These results were obtained by using a three-dimensional finite element analysis. An angle-ply, laminated thin shell with fiber orientation of (theta/-theta)(sub 2) was subjected to compressive mechanical loads. The laminated thin shell had a cylindrical geometry. The laminate contained T300 graphite fibers embedded in an intermediate-modulus, high-strength (IMHS) matrix. The fiber volume fraction was 55 percent and the moisture content was 2 percent. The residual stresses induced into the laminate structure during the curing were taken into account. Parametric studies were performed to examine the effect on the critical buckling load of the following parameters: cylinder length and thickness, internal hydrostatic pressure, different ply thicknesses, different temperature profiles through the thickness of the structure, and different lay up configurations and fiber volume fractions. In conjunction with these parameters the ply orientation was varied from 0 deg to 90 deg. Seven ply angles were examined: 0 deg, 15 deg, 30 deg, 45 deg, 60 deg, 75 deg, and 90 deg. The results show that the ply angle theta and the laminate thickness had significant effects on the critical buckling load. The fiber volume fraction, the fiber orientations, and the internal hydrostatic pressure had important effects on the critical buckling load. The cylinder length had a moderate influence on the buckling load. The thin shell with (theta/-theta)(sub 2) or (theta/-theta)(sub s) angle-ply laminate had better buckling-load performance than the thin shell with (theta)(sub 4) angle-ply laminate. The temperature profiles through the laminate thickness and various laminates with the different ply thicknesses has insignificant effects on the buckling behavior of the thin shells.

  17. Deficiencies in lamin B1 and lamin B2 cause neurodevelopmental defects and distinct nuclear shape abnormalities in neurons

    PubMed Central

    Coffinier, Catherine; Jung, Hea-Jin; Nobumori, Chika; Chang, Sandy; Tu, Yiping; Barnes, Richard H.; Yoshinaga, Yuko; de Jong, Pieter J.; Vergnes, Laurent; Reue, Karen; Fong, Loren G.; Young, Stephen G.

    2011-01-01

    Neuronal migration is essential for the development of the mammalian brain. Here, we document severe defects in neuronal migration and reduced numbers of neurons in lamin B1–deficient mice. Lamin B1 deficiency resulted in striking abnormalities in the nuclear shape of cortical neurons; many neurons contained a solitary nuclear bleb and exhibited an asymmetric distribution of lamin B2. In contrast, lamin B2 deficiency led to increased numbers of neurons with elongated nuclei. We used conditional alleles for Lmnb1 and Lmnb2 to create forebrain-specific knockout mice. The forebrain-specific Lmnb1- and Lmnb2-knockout models had a small forebrain with disorganized layering of neurons and nuclear shape abnormalities, similar to abnormalities identified in the conventional knockout mice. A more severe phenotype, complete atrophy of the cortex, was observed in forebrain-specific Lmnb1/Lmnb2 double-knockout mice. This study demonstrates that both lamin B1 and lamin B2 are essential for brain development, with lamin B1 being required for the integrity of the nuclear lamina, and lamin B2 being important for resistance to nuclear elongation in neurons. PMID:21976703

  18. Eddy current losses in ferromagnetic laminations

    SciTech Connect

    Serpico, C.; Visone, C.; Mayergoyz, I. D.; Basso, V.; Miano, G.

    2000-05-01

    It is demonstrated through the comparison of analytical, numerical, and experimental results that the existence of excess eddy current losses can be explained by the peculiar nature of the nonlinear diffusion of electromagnetic fields in magnetically nonlinear laminations. The essence of this peculiar nature is that nonlinear diffusion occurs as inward progress of almost rectangular profiles of magnetic flux density of variable height. Approximating actual profiles of magnetic flux density by rectangular ones, the problem of nonlinear diffusion can be treated analytically by using a simple model. The accuracy and the limit of applicability of the rectangular profile model are discussed by comparing its predictions with finite elements numerical solutions of nonlinear diffusion equation as well as with experimental results. (c) 2000 American Institute of Physics.

  19. Reliability analysis of ceramic matrix composite laminates

    NASA Technical Reports Server (NTRS)

    Thomas, David J.; Wetherhold, Robert C.

    1991-01-01

    At a macroscopic level, a composite lamina may be considered as a homogeneous orthotropic solid whose directional strengths are random variables. Incorporation of these random variable strengths into failure models, either interactive or non-interactive, allows for the evaluation of the lamina reliability under a given stress state. Using a non-interactive criterion for demonstration purposes, laminate reliabilities are calculated assuming previously established load sharing rules for the redistribution of load as the failure of laminae occur. The matrix cracking predicted by ACK theory is modeled to allow a loss of stiffness in the fiber direction. The subsequent failure in the fiber direction is controlled by a modified bundle theory. Results using this modified bundle model are compared with previous models which did not permit separate consideration of matrix cracking, as well as to results obtained from experimental data.

  20. Compression failure of angle-ply laminates

    NASA Technical Reports Server (NTRS)

    Peel, L. D.; Hyer, M. W.; Shuart, M. J.

    1992-01-01

    Test results from the compression loading of (+ or - Theta/ - or + Theta)(sub 6s) angle-ply IM7-8551-7a specimens, 0 less than or = Theta less than or = 90 degs, are presented. The observed failure strengths and modes are discussed, and typical stress-strain relations shown. Using classical lamination theory and the maximum stress criterion, an attempt is made to predict failure stress as a function of Theta. This attempt results in poor correlation with test results and thus a more advanced model is used. The model, which is based on a geometrically nonlinear theory, and which was taken from previous work, includes the influence of observed layer waviness. The waviness is described by the wave length and the wave amplitude. The theory is briefly described and results from the theory are correlated with test results. It is shown that by using levels of waviness observed in the specimens, the correlation between predictions and observations is good.

  1. Laminated wave turbulence: Generic algorithms iii

    NASA Astrophysics Data System (ADS)

    Kartashova, Elena; Kartashov, Alexey

    2007-07-01

    Model of laminated wave turbulence allows to study statistical and discrete layers of turbulence in the frame of the same model. Statistical layer is described by Zakharov-Kolmogorov energy spectra in the case of irrational enough dispersion function. Discrete layer is covered by some system(s) of Diophantine equations while their form is determined by wave dispersion function. This presents a very special computational challenge to solve Diophantine equations in many variables, usually 6 to 8, in high degrees, say 16, in integers of order 1016 and more. Generic algorithms for solving this problem in the case of irrational dispersion function have been presented in our previous papers (corresponds to many types of water waves). In this paper, we present a new algorithm for the case of rational dispersion functions (atmospheric planetary waves, drift waves, etc.)

  2. Development of a Heterogeneous Laminating Resin

    NASA Technical Reports Server (NTRS)

    Gosnell, R.

    1984-01-01

    The feasibility of toughening the common types of matrix resins such as Narmco 5208 by utilizing a heterogeneous additive was examined. Some basic concepts and principles in the toughening of matrix resins for advanced composites were studied. The following conclusions were advanced: (1) the use of damage volume as a guide for measurement of impact resistance appears to be a valid determination; (2) short beam shear is a good test to determine the effect of toughening agents on mechanical properties; (3) rubber toughening results in improved laminate impact strength, but with substantial loss in high temperature dry and wet strength; (4) in the all-epoxy systems, the polycarbonate toughening agent seemed to be the most effective, although hot-wet strength is sacrificed; ABS was not as effective; and (5) in general, the toughened all-epoxy systems showed better damage tolerance, but less hot-wet strength; toughened bismaleimides had better hot-wet strength.

  3. Permeability After Impact Testing of Composite Laminates

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.

    2003-01-01

    Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

  4. Permeability After Impact Testing of Composite Laminates

    NASA Technical Reports Server (NTRS)

    Nettles, A.T.; Munafo, Paul (Technical Monitor)

    2002-01-01

    Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

  5. Analysis of "Kiss" Bonds Between Composite Laminates

    NASA Astrophysics Data System (ADS)

    Poveromo, Scott L.; Earthman, James C.

    2014-06-01

    One of the leading challenges to designing lightweight, cost-effective bonded structures is to detect low shear strength "kiss" bonds where no other defects such as voids and cracks exist. To develop a nondestructive testing method that is sensitive to kiss bonds, standards need to be fabricated with known strength values. In the current work, we attempt to create kiss bonds in between carbon fiber composite laminates that have been bonded with epoxy film adhesive and epoxy paste adhesive. Based on ultrasonic testing, when creating true kiss bonds using film adhesives, a complete disbond could not be avoided because of thermally induced stresses during the high-temperature cure. However, further work demonstrated that kiss bonds can be formed using room-temperature curable epoxy paste adhesives by creating an amine blush on the epoxy surface or applying a release agent on the bonding surfaces.

  6. Micromechanics of composite laminate compression failure

    NASA Technical Reports Server (NTRS)

    Guynn, E. Gail; Bradley, Walter L.

    1986-01-01

    The Dugdale analysis for metals loaded in tension was adapted to model the failure of notched composite laminates loaded in compression. Compression testing details, MTS alignment verification, and equipment needs were resolved. Thus far, only 2 ductile material systems, HST7 and F155, were selected for study. A Wild M8 Zoom Stereomicroscope and necessary attachments for video taping and 35 mm pictures were purchased. Currently, this compression test system is fully operational. A specimen is loaded in compression, and load vs shear-crippling zone size is monitored and recorded. Data from initial compression tests indicate that the Dugdale model does not accurately predict the load vs damage zone size relationship of notched composite specimens loaded in compression.

  7. Impact resistance of composite laminated sandwich plates

    NASA Astrophysics Data System (ADS)

    Kim, Chun-Gon; Jun, Eui-Jin

    1992-01-01

    Investigated are the effects of face layup sequence and core density of a sandwich plate on the impact delamination area of the laminated facesheet. The sandwich plate is made of graphite/epoxy faces and Nomex honeycomb core. The size and shape of delamination due to impact at each interply location have been measured by the room temperature deply technique. The shape of the interply delamination under impact is, in general, found to be two-lobed. The shape exhibits very peculiar regularity under various experimental conditions. The quantitative measurement of delamination size has shown that the face layup with small relative orientation between adjacent plies and high density core are desirable in sandwich plates to reduce the impact delamination.

  8. Laminated metals composites fracture and ballistic impact behavior

    SciTech Connect

    Lesuer, D.R.; Syn, C.K.; Sherby, O.D.; Wadsworth, J.

    1998-01-20

    Recent advances in the fracture and ballistic impact response of laminated metal composites (LMCs) are reviewed. The laminate structure can provide significant improvements to these properties relative to the component materials. Typical fracture and ballistic impact properties in LMCs are illustrated for systems containing Al alloys and Al matrix composites. The unique mechanisms operating in a layered structure that contribute to fracture or ballistic impact resistance are discussed. The influence of laminate architecture, component material properties and interface strength on mechanisms and properties are briefly reviewed for these Al-based LMCs.

  9. Notched strength of composite laminates: Predictions and experiments - A review

    NASA Technical Reports Server (NTRS)

    Awerbuch, J.; Madhukar, M. S.

    1985-01-01

    A self-contained review of several semiempirical fracture models for predicting notched strength of composite laminates is presented, based on notched strength data on 70 different laminate configurations of graphite/epoxy, boron/aluminum, and graphite/polyimide. Emphasis is placed on experimental results concerning such failure factors as delamination, splitting, and size of damage zone. Moreover, the fracture model parameters are correlated with the notch sensitivity of composite laminates, and the applicability of the correlations in describing the material notch sensitivity is evaluated. The predictions provided by the different models were found to be identical for all practical purposes.

  10. Accurate stress resultants equations for laminated composite deep thick shells

    SciTech Connect

    Qatu, M.S.

    1995-11-01

    This paper derives accurate equations for the normal and shear force as well as bending and twisting moment resultants for laminated composite deep, thick shells. The stress resultant equations for laminated composite thick shells are shown to be different from those of plates. This is due to the fact the stresses over the thickness of the shell have to be integrated on a trapezoidal-like shell element to obtain the stress resultants. Numerical results are obtained and showed that accurate stress resultants are needed for laminated composite deep thick shells, especially if the curvature is not spherical.

  11. Vibration analysis of rotating thin laminated composite shell of revolution

    SciTech Connect

    Suzuki, K.; Shikanai, G.; Takayama, K.

    1995-11-01

    An exact solution procedure is presented for solving free vibrations of a rotating thin laminated composite shell of revolution having meridionally constant curvature. Based on the classical lamination theory, equations of motion and boundary conditions are obtained from the stationally conditions of the Lagrangian. The equations of motion are solved exactly by using a power series expansion for symmetrically laminated, cross-ply shells. Frequencies and mode shapes of the shells having both ends clamped and both ends freely supported are presented showing their variations with rotating angular velocity, number of laminae and other parameters.

  12. Axisymmetric vibrations of laminated composite conical shells with varying thickness

    SciTech Connect

    Shikanai, G.; Suzuki, K.; Kojima, M.

    1995-11-01

    An exact solution procedure is presented for solving axisymmetric free vibrations of laminated composite conical shells with varying thickness. Based on the classical lamination theory neglecting shear deformation and rotary inertia, equations of motion and boundary conditions are obtained from the stationary conditions of the Lagrangian. The equations of motion are solved exactly by using a power series expansion for symmetrically laminated, cross-ply conical shells. Numerical studies are made for conical shells having both ends clamped to show the effects of the number of laminae, stacking sequences and other parameters upon the frequencies.

  13. An approximate solution for interlaminar stresses in composite laminates

    NASA Technical Reports Server (NTRS)

    Rose, Cheryl A.; Herakovich, Carl T.

    1993-01-01

    An efficient approximate solution for interlaminar stresses in finite width, symmetric and unsymmetric laminated composites subjected to axial and/or bending loads is presented. The solution is based upon statically admissible stress fields which take into consideration local property mismatch effects and global equilibrium requirements. Unknown constants in the assumed stress states are determined through minimization of the laminate complementary energy. Typical results are presented for through-thickness and interlaminar stress distributions for angle-ply and cross-ply laminates subjected to axial loading. It is shown that the present formulation represents an improved, efficient approximate solution for interlaminar stresses.

  14. Analysis of a hybrid-undirectional buffer strip laminate

    NASA Technical Reports Server (NTRS)

    Dharani, L. R.; Goree, J. G.

    1983-01-01

    A method of analysis capable of predicting accurately the fracture behavior of a unidirectional composite laminate containing symmetrically placed buffer strips is presented. As an example, for a damaged graphite/epoxy laminate, the results demonstrate the manner in which to select the most efficient combination of buffer strip properties necessary to inhibit crack growth. Ultimate failure of the laminate after the arrest can occur under increasing load either by continued crack extension through the buffer strips or the crack can jump the buffer strips. For some typical hybrid materials it is found that a buffer strip spacing to width ratio of about four to one is the most efficient.

  15. Interlaminar stresses in composite laminates: A perturbation analysis

    NASA Technical Reports Server (NTRS)

    Hsu, P. W.; Herakovich, C. T.

    1976-01-01

    A general method of solution for an elastic balanced symmetric composite laminate subject to a uniaxial extension was developed based upon a perturbation analysis of a limiting free body containing an interfacial plane. The solution satisfies more physical requirements and boundary conditions than previous investigations, and predicts smooth continuous interlaminar stresses with no instabilities. It determines the finite maximum intensity for the interlaminar normal stress in all laminates, provides mathematical evidences for the singular stresses in angle-ply laminates, suggests the need for the experimental determination of an important problem parameter, and introduces a viable means for solving related problems of practical interest.

  16. Analysis of a hybrid, unidirectional buffer strip laminate

    NASA Technical Reports Server (NTRS)

    Dharani, L. R.; Goree, J. G.

    1983-01-01

    A method of analysis capable of predicting accurately the fracture behavior of a unidirectional composite laminate containing symmetrically placed buffer strips is presented. As an example, for a damaged graphite/epoxy laminate, the results demonstrate the manner in which to select the most efficient combination of buffer strip properties necessary to inhibit crack growth. Ultimate failure of the laminate after crack arrest can occur under increasing load either by continued crack extension through the buffer strips or the crack can jump the buffer strips. For some typical hybrid materials it is found that a buffer strip spacing-to-width ratio of about four to one is the most efficient.

  17. Multi-Layer Laminated Thin Films for Inflatable Structures

    NASA Technical Reports Server (NTRS)

    Yavrouian, Andre; Plett, Gary; Mannella, Jerami

    2005-01-01

    Special-purpose balloons and other inflatable structures would be constructed as flexible laminates of multiple thin polymeric films interspersed with layers of adhesive, according to a proposal. In the original intended application, the laminate would serve as the envelope of the Titan Aerobot a proposed robotic airship for exploring Titan (one of the moons of Saturn). Potential terrestrial applications for such flexible laminates could include blimps and sails. In the original application, the multi-layered laminate would contain six layers of 0.14-mil (0.0036-mm)-thick Mylar (or equivalent) polyethylene terephthalate film with a layer of adhesive between each layer of Mylar . The overall thickness and areal density of this laminate would be nearly the same as those of 1-mil (0.0254-mm)-thick monolayer polyethylene terephthalate sheet. However, the laminate would offer several advantages over the monolayer sheet, especially with respect to interrelated considerations of flexing properties, formation of pinholes, and difficulty or ease of handling, as discussed next. Most of the damage during flexing of the laminate would be localized in the outermost layers, where the radii of bending in a given bend would be the largest and, hence, the bending stress would be the greatest. The adverse effects of formation of pinholes would be nearly completely mitigated in the laminate because a pinhole in a given layer would not propagate to adjacent layers. Hence, the laminate would tend to remain effective as a barrier to retain gas. Similar arguments can be made regarding cracks: While a crack could form as a result of stress or a defect in the film material, a crack would not propagate into adjacent layers, and the adjacent layer(s) would even arrest propagation of the crack. In the case of the monolayer sheet, surface damage (scratches, dents, permanent folds, pinholes, and the like) caused by handling would constitute or give rise to defects that could propagate through

  18. Prediction of microcracking in composite laminates under thermomechanical loading

    SciTech Connect

    Maddocks, J.R.; Mcmanus, H.L.

    1995-01-01

    Composite laminates used in space structures are exposed to both thermal and mechanical loads. Cracks in the matrix form, changing the laminate thermoelastic properties. An analytical methodology is developed to predict microcrack density in a general laminate exposed to an arbitrary thermomechanical load history. The analysis uses a shear lag stress solution in conjunction with an energy-based cracking criterion. Experimental investigation was used to verify the analysis. Correlation between analysis and experiment is generally excellent. The analysis does not capture machining-induced cracking, or observed delayed crack initiation in a few ply groups, but these errors do not prevent the model from being a useful preliminary design tool.

  19. Improved PMR Polyimides For Heat-Stable Laminates

    NASA Technical Reports Server (NTRS)

    Vannucci, R. D.; Malarik, D. C.; Papadapoulos, D. S.; Waters, John F.

    1994-01-01

    Second-generation PMR-type polyimides (PMR-II polyimides) of enhanced thermo-oxidative stability prepared by substitution of para-aminostyrene (PAS) end caps for nadic-ester (NE) end caps used in prior PMR-II polyimides. Laminates unidirectionally reinforced with graphite fibers and made with PAS-capped resins exhibited thermo-oxidative stabilities significantly greater than those of similar laminates made with NE-capped PMR-II resins. One new laminate exhibited high retention of weight and strength after 1,000 h of exposure to air at 371 degrees C.

  20. Wave propagation in graphite/epoxy laminates due to impact

    NASA Technical Reports Server (NTRS)

    Tan, T. M.; Sun, C. T.

    1982-01-01

    The low velocity impact response of graphite-epoxy laminates is investigated theoretically and experimentally. A nine-node isoparametric finite element in conjunction with an empirical contact law was used for the theoretical investigation. Flat laminates subjected to pendulum impact were used for the experimental investigation. Theoretical results are in good agreement with strain gage experimental data. The collective results of the investigation indicate that the theoretical procedure describes the impact response of the laminate up to about 150 in/sec. impact velocity.

  1. Optimal Synthesis of Hot Composite Laminates with Interphase Layers

    NASA Technical Reports Server (NTRS)

    Rabzak, Christopher; Saravanos, Dimitris A.; Chamis, Christos C.

    1993-01-01

    A method for the optimal grading of a single interphase layer in metal matrix composite laminates for the minimization of residual stresses is described. The capability to simultaneously tailor some fabrication parameters is also incorporated. Applications for unidirectional, cross-ply and quasi-isotropic Graphite/Copper laminates are investigated to assess the potential of interphase layer in reducing matrix residual stresses in various laminate configurations. Simultaneous optimization of interphase and fabrication characteristics appears to be more effective in decreasing residual stresses. The results also indicate that the interphase layer is more effective in lowering residual stresses in unidirectional composites and selectively within individual plies of a laminate. Embedded interphase layers in all the plies did not produce a significant global reduction in residual stresses.

  2. Characterization of delamination onset and growth in a composite laminate

    NASA Technical Reports Server (NTRS)

    Obrien, T. K.

    1981-01-01

    The onset and growth of delaminations in unnotched (+ or - 30/+ or - 30/90/90 bar) sub S graphite epoxy laminates is described quantitatively. These laminates, designed to delaminate at the edges under tensile loads, were tested and analyzed. Delamination growth and stiffness loss were monitored nondestructively. Laminate stiffness decreased linearly with delamination size. The strain energy release rate, G, associated with delamination growth, was calculated from two analyses. A critical G for delamination onset was determined, and then was used to predict the onset of delaminations in (+45 sub n/-45 sub n/o sub n/90 sub n) sub s (n=1,2,3) laminates. A delamination resistance curve (R curve) was developed to characterize the observed stable delamination growth under quasi static loading. A power law correlation between G and delamination growth rates in fatigue was established.

  3. Nonlinear analysis of laminated fibrous composites. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Renieri, G. D.; Herakovich, C. T.

    1976-01-01

    A computerized analysis of the nonlinear behavior of fibrous composite laminates including axial loading, thermal loading, temperature dependent properties, and edge effects is presented. Ramberg-Osgood approximations are used to represent lamina stress-strain behavior and percent retention curves are employed to model the variation of properties with temperature. Balanced, symmetric laminates comprised of either boron/epoxy, graphite/epoxy, or borsic-aluminum are analyzed using a quasi-three-dimensional finite element analysis. Results are presented for the interlaminar stress distributions in cross-ply, angle-ply, and more complex laminates. Nonlinear stress-strain curves for a variety of composite laminates in tension and compression are obtained and compared to other existing theories and experimental results.

  4. Modelling of thick composites using a layerwise laminate theory

    NASA Technical Reports Server (NTRS)

    Robbins, D. H., Jr.; Reddy, J. N.

    1993-01-01

    The layerwise laminate theory of Reddy (1987) is used to develop a layerwise, two-dimensional, displacement-based, finite element model of laminated composite plates that assumes a piecewise continuous distribution of the tranverse strains through the laminate thickness. The resulting layerwise finite element model is capable of computing interlaminar stresses and other localized effects with the same level of accuracy as a conventional 3D finite element model. Although the total number of degrees of freedom are comparable in both models, the layerwise model maintains a 2D-type data structure that provides several advantages over a conventional 3D finite element model, e.g. simplified input data, ease of mesh alteration, and faster element stiffness matrix formulation. Two sample problems are provided to illustrate the accuracy of the present model in computing interlaminar stresses for laminates in bending and extension.

  5. Nuclear lamins during gametogenesis, fertilization and early development

    NASA Technical Reports Server (NTRS)

    Maul, G. G.; Schatten, G.

    1986-01-01

    The distribution of lamins (described by Gerace, 1978, as major proteins of nuclear envelope) during gametogenesis, fertilization, and early development was investigated in germ cells of a mouse (Mus musculus), an echinoderm (Lytechinus variegatus), and the surf clam (Spisula solidissima) was investigated in order to determine whether the differences detected could be correlated with differences in the function of cells in these stages of the germ cells. In order to monitor the behavior of lamins, the gametes and embryos were labeled with antibodies to lamins A, C, and B extracted from autoimmune sera of patients with scleroderma and Lupus erythematosus. Results indicated that lamin B could be identified in nuclear envelopes on only those nuclei where chromatin is attached and where RNA synthesis takes place.

  6. Analysis of a unidirectional, symmetric buffer strip laminate with damage

    NASA Technical Reports Server (NTRS)

    Dharani, L. R.; Goree, J. G.

    1984-01-01

    A method for predicting the fracture behavior of hybrid buffer strip laminates is presented in which the classical shear-lag model is used to represent the shear stress distribution between adjacent fibers. The method is demonstrated by applying it to a notched graphite/epoxy laminate, and the results show clearly the manner in which the most efficient combination of buffer strip properties can be selected in order to arrest the crack. The ultimate failure stress of the laminate is plotted vs the buffer strip width. It is shown that in the case of graphite-epoxy and S-glass epoxy laminates, the optimum buffer strip spacing to width ratio should be about four to one.

  7. Structural and Dielectric Properties of Subnanometric Laminates of Binary Oxides.

    PubMed

    Kahouli, Abdelkader; Lebedev, Oleg; Ben Elbahri, Marwa; Mercey, Bernard; Prellier, Wilfrid; Riedel, Stefan; Czernohorsky, Malte; Lallemand, Florent; Bunel, Catherine; Lüders, Ulrike

    2015-11-25

    Capacitors with a dielectric material consisting of amorphous laminates of Al2O3 and TiO2 with subnanometer individual layer thicknesses can show strongly enhanced capacitance densities compared to the bulk or laminates with nanometer layer thickness. In this study, the structural and dielectric properties of such subnanometer laminates grown on silicon by state-of-the-art atomic layer deposition are investigated with varying electrode materials. The laminates show a dielectric constant reaching 95 combined with a dielectric loss (tan δ) of about 0.2. The differences of the observed dielectric properties in capacitors with varying electrodes indicate that chemical effects at the interface with the TiN electrode play a major role, while the influence of the local roughness of the individual layers is rather limited. PMID:26523935

  8. Laminated rare earth structure and method of making

    DOEpatents

    Senor, David J [West Richland, WA; Johnson, Roger N [Richland, WA; Reid, Bruce D [Pasco, WA; Larson, Sandra [Richland, WA

    2002-07-30

    A laminated structure having two or more layers, wherein at least one layer is a metal substrate and at least one other layer is a coating comprising at least one rare earth element. For structures having more than two layers, the coating and metal substrate layers alternate. In one embodiment of the invention, the structure is a two-layer laminate having a rare earth coating electrospark deposited onto a metal substrate. In another embodiment of the invention, the structure is a three-layer laminate having the rare earth coating electrospark deposited onto a first metal substrate and the coating subsequently abonded to a second metal substrate. The bonding of the coating to the second metal substrate may be accomplished by hot pressing, hot rolling, high deformation rate processing, or combinations thereof. The laminated structure may be used in nuclear components where reactivity control or neutron absorption is desired and in non-nuclear applications such as magnetic and superconducting films.

  9. Calculation of the room-temperature shapes of unsymmetric laminates

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.

    1981-01-01

    A theory explaining the characteristics of the cured shapes of unsymmetric laminates is presented. The theory is based on an extension of classical lamination theory which accounts for geometric nonlinearities. A Rayleigh-Ritz approach to minimizing the total potential energy is used to obtain quantitative information regarding the room temperature shapes of square T300/5208 (0(2)/90(2))T and (0(4)/90(4))T graphite-epoxy laminates. It is shown that, depending on the thickness of the laminate and the length of the side the square, the saddle shape configuration is actually unstable. For values of length and thickness that render the saddle shape unstable, it is shown that two stable cylindrical shapes exist. The predictions of the theory are compared with existing experimental data.

  10. 11. Detail of laminated arch beams, radiators, pews and portion ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Detail of laminated arch beams, radiators, pews and portion of the office to the left of the sanctuary, facing north - Mountain Home Air Force Base, Base Chapel, 350 Willow Street, Cantonment Area, Mountain Home, Elmore County, ID

  11. Laminated metamaterial flat lens at millimeter-wave frequencies.

    PubMed

    Kitayama, Daisuke; Yaita, Makoto; Song, Ho-Jin

    2015-09-01

    A flat and thin shape is obviously advantageous not only in terms of reducing the volume of a device, but also in handling and using it. Particularly, laminating or stacking flat devices is an intuitive and straightforward way of tailoring performance and functions. Here, we experimentally demonstrated a laminated flat lens for millimeter-wave frequencies that is based on split-ring resonators (SRRs) composed of multiple layers with different and/or identical index profiles and that exhibits characteristics that are linear combinations of those of the individual lenses. Since the characteristics of the lenses of each layer are preserved regardless of the neighbouring layers, the desired functionalities can be easily implemented simply by laminating elementary lenses designed already. When we laminated two lenses designed for bending or focusing incoming waves at 120 GHz, we clearly observed that the outgoing waves collimated and bended as desired. PMID:26368436

  12. Tying up loose ends: telomeres, genomic instability and lamins.

    PubMed

    Gonzalo, Susana; Eissenberg, Joel C

    2016-04-01

    On casual inspection, the eukaryotic nucleus is a deceptively simple organelle. Far from being a bag of chromatin, the nucleus is, in some ways, a structural and functional extension of the chromosomes it contains. Recently, interest has intensified in how chromosome compartmentalization and dynamics affect nuclear function. Different studies uncovered functional interactions between chromosomes and the filamentous nuclear meshwork comprised of lamin proteins. Here, we summarize recent research suggesting that telomeres, the capping structures that protect chromosome ends, are stabilized by lamin-binding and that alterations in nuclear lamins lead to defects in telomere compartmentalization, homeostasis and function. Telomere dysfunction contributes to the genomic instability that characterizes aging-related diseases, and might be an important factor in the pathophysiology of lamin-related diseases. PMID:27010504

  13. 10. Detail view of pendant lamps, laminated arch beams and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Detail view of pendant lamps, laminated arch beams and ceiling structure, facing north - Mountain Home Air Force Base, Base Chapel, 350 Willow Street, Cantonment Area, Mountain Home, Elmore County, ID

  14. Solar-Cell Encapsulation by One-Step Lamination

    NASA Technical Reports Server (NTRS)

    Sarbolouki, M. N.

    1983-01-01

    Simple method of potting solar cells reduces encapsulating to one-step lamination process. Simplified process saves time and expense. Potting material is added to two inside faces of solar-cell assembly before they are sandwiched and cured.

  15. Progressive Failure Analysis Methodology for Laminated Composite Structures

    NASA Technical Reports Server (NTRS)

    Sleight, David W.

    1999-01-01

    A progressive failure analysis method has been developed for predicting the failure of laminated composite structures under geometrically nonlinear deformations. The progressive failure analysis uses C(exp 1) shell elements based on classical lamination theory to calculate the in-plane stresses. Several failure criteria, including the maximum strain criterion, Hashin's criterion, and Christensen's criterion, are used to predict the failure mechanisms and several options are available to degrade the material properties after failures. The progressive failure analysis method is implemented in the COMET finite element analysis code and can predict the damage and response of laminated composite structures from initial loading to final failure. The different failure criteria and material degradation methods are compared and assessed by performing analyses of several laminated composite structures. Results from the progressive failure method indicate good correlation with the existing test data except in structural applications where interlaminar stresses are important which may cause failure mechanisms such as debonding or delaminations.

  16. Fatigue of notched fiber composite laminates. Part 1: Analytical model

    NASA Technical Reports Server (NTRS)

    Mclaughlin, P. V., Jr.; Kulkarni, S. V.; Huang, S. N.; Rosen, B. W.

    1975-01-01

    A description is given of a semi-empirical, deterministic analysis for prediction and correlation of fatigue crack growth, residual strength, and fatigue lifetime for fiber composite laminates containing notches (holes). The failure model used for the analysis is based upon composite heterogeneous behavior and experimentally observed failure modes under both static and fatigue loading. The analysis is consistent with the wearout philosophy. Axial cracking and transverse cracking failure modes are treated together in the analysis. Cracking off-axis is handled by making a modification to the axial cracking analysis. The analysis predicts notched laminate failure from unidirectional material fatique properties using constant strain laminate analysis techniques. For multidirectional laminates, it is necessary to know lamina fatique behavior under axial normal stress, transverse normal stress and axial shear stress. Examples of the analysis method are given.

  17. Determination of the technical constants of laminates in oblique directions

    NASA Technical Reports Server (NTRS)

    Vidouse, F.

    1979-01-01

    An off-axis tensile test theory based on Hooke's Law is applied to glass fiber reinforced laminates. A corrective parameter dependent on the characteristics of the strain gauge used is introduced by testing machines set up for isotropic materials. Theoretical results for a variety of strain gauges are compared with those obtained by a finite element method and with experimental results obtained on laminates reinforced with glass.

  18. Laminated microchannel devices, mixing units and method of making same

    DOEpatents

    Bennett, Wendy D [Kennewick, WA; Hammerstrom, Donald J [West Richland, WA; Martin, Peter M [Kennewick, WA; Matson, Dean W [Kennewick, WA

    2002-10-17

    A laminated microchannel device is described in which there is a unit operation process layer that has longitudinal channel. The longitudinal channel is cut completely through the layer in which the unit process operation resides. Both the device structure and method of making the device provide significant advantages in terms of simplicity and efficiency. A static mixing unit that can be incorporated in the laminated microchannel device is also described.

  19. Support Assembly for Composite Laminate Materials During Roll Press Processing

    NASA Technical Reports Server (NTRS)

    Catella, Luke A.

    2011-01-01

    A composite laminate material is supported during the roll press processing thereof by an assembly having: first and second perforated films disposed adjacent to first and second opposing surfaces of a mixture of uncured resin and fibers defining the composite laminate material, a gas permeable encasement surrounding the mixture and the first and second films, a gas impervious envelope sealed about the gas permeable encasement, and first and second rigid plates clamped about the gas impervious envelope.

  20. Fracture analysis of local delaminations in laminated composites

    NASA Technical Reports Server (NTRS)

    Sriram, P.; Armanios, Erian A.

    1988-01-01

    A shear deformation model was developed to analyze local delaminations growing from transverse cracks in 90 degree plies located around the mid plane of symmetric laminates. The predictions of the model agree reasonably with experimental data from T300/934 graphite epoxy laminates. The predicted behavior is such that, in combination with an edge delamination model, the critical loads can be predicted accurately in the range of n from .5 to 8.

  1. Review on antibacterial biocomposites of structural laminated veneer lumber

    PubMed Central

    Chen, Zi-xiang; Lei, Qiong; He, Rui-lin; Zhang, Zhong-feng; Chowdhury, Ahmed Jalal Khan

    2015-01-01

    In this review, the characteristics and applications of structural laminated veneer lumber made from planted forest wood is introduced, and its preparation is explained, including various tree species and slab qualities, treatments for multiple effects and reinforced composites. The relevant factors in the bonding technology and pressing processes as well as the mechanical properties, research direction and application prospects of structural laminated veneer lumber made from planted forest wood are discussed. PMID:26858559

  2. Damage Tolerance of Composite Laminates from an Empirical Perspective

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.

    2009-01-01

    Damage tolerance consists of analysis and experimentation working together. Impact damage is usually of most concern for laminated composites. Once impacted, the residual compression strength is usually of most interest. Other properties may be of more interest than compression (application dependent). A damage tolerance program is application specific (not everyone is building aircraft). The "Building Block Approach" is suggested for damage tolerance. Advantage can be taken of the excellent fatigue resistance of damaged laminates to save time and costs.

  3. Response of automated tow placed laminates to stress concentrations

    NASA Technical Reports Server (NTRS)

    Cairns, Douglas S.; Ilcewicz, Larry B.; Walker, Tom

    1993-01-01

    In this study, the response of laminates with stress concentrations is explored. Automated Tow Placed (ATP, also known as Fiber Placement) laminates are compared to conventional tape layup manufacturing. Previous tensile fracture tests on fiber placed laminates show an improvement in tensile fracture of large notches over 20 percent compared to tape layup laminates. A hierarchial modeling scheme is presented. In this scheme, a global model is developed for laminates with notches. A local model is developed to study the influence of inhomogeneities at the notch tip, which are a consequence of the fiber placement manufacturing technique. In addition, a stacked membrane model was developed to study delaminations and splitting on a ply-by-ply basis. The results indicate that some benefit with respect to tensile fracture (up to 11 percent) can be gained from inhomogeneity alone, but that the most improvement may be obtained with splitting and delaminations which are more severe in the case of fiber placement compared to tape layup. Improvements up to 36 percent were found from the model for fiber placed laminates with damage at the notch tip compared to conventional tape layup.

  4. Transparent, resilient human amniotic membrane laminates for corneal transplantation.

    PubMed

    Hariya, Takehiro; Tanaka, Yuji; Yokokura, Shunji; Nakazawa, Toru

    2016-09-01

    This study evaluated a new technique to toughen and optically clarify human amniotic membrane (AM) tissue, which is naturally thin and clouded, and determined the suitability of the altered tissue for corneal transplantation. The technique created a tissue laminate by repeatedly depositing wet layers of AM and dehydrating them, followed by chemical cross-linking to tighten integration at the layer interfaces and within the layers, thereby improving the physical properties of the laminates by increasing light transmittance and mechanical strength. Interestingly, this improvement only occurred in laminates with at least 4 layers. Cross-linking also improved the resistance of the laminates to collagenase degradation, such as occurs in corneal melting. This study also confirmed that the AM tissue was biocompatible by inserting AM monolayers into the corneal stroma of rabbits, and by performing lamellar keratoplasty in rabbits with cross-linked AM laminates. The laminates were sufficiently thick and resilient to need only one set of sutures, whereas in previously described multi-layer AM transplantation technique, each layer required separate sutures. The current findings are a promising advance in the engineering of novel biomaterials and the alteration of existing tissues for medical use. PMID:27267629

  5. BioID Identification of Lamin-Associated Proteins.

    PubMed

    Mehus, Aaron A; Anderson, Ruthellen H; Roux, Kyle J

    2016-01-01

    A- and B-type lamins support the nuclear envelope, contribute to heterochromatin organization, and regulate a myriad of nuclear processes. The mechanisms by which lamins function in different cell types and the mechanisms by which lamin mutations cause over a dozen human diseases (laminopathies) remain unclear. The identification of proteins associated with lamins is likely to provide fundamental insight into these mechanisms. BioID (proximity-dependent biotin identification) is a unique and powerful method for identifying protein-protein and proximity-based interactions in living cells. BioID utilizes a mutant biotin ligase from bacteria that is fused to a protein of interest (bait). When expressed in living cells and stimulated with excess biotin, this BioID-fusion protein promiscuously biotinylates directly interacting and vicinal endogenous proteins. Following biotin-affinity capture, the biotinylated proteins can be identified using mass spectrometry. BioID thus enables screening for physiologically relevant protein associations that occur over time in living cells. BioID is applicable to insoluble proteins such as lamins that are often refractory to study by other methods and can identify weak and/or transient interactions. We discuss the use of BioID to elucidate novel lamin-interacting proteins and its applications in a broad range of biological systems, and provide detailed protocols to guide new applications. PMID:26778550

  6. The effect of lamination angle on polymer retention

    SciTech Connect

    Gao, H.W.

    1992-09-01

    Polymer retention may be affected by the reservoir geological structure due to lamination of the mineral surfaces. These laminae are very prevalent in Class I reservoirs. To account for the effect of lamination angle on polymer retention, several corefloods with three fired, rectangular, Berea sandstone cores were conducted. The three cores were cut at three different angles, 0, 30, and 90 degrees, with respect to the direction of laminations. A multiple slug retention method was used to determine the retention of a biopolymer in each core. Tracer tests were conducted before and after the biopolymer flow to determine how the retained biopolymer affected the fluid advance. A computed tomography (CT) scanning method was used to monitor the advance of the tracer. All corefloods and tracer tests were conducted at low flow rates similar to that in reservoirs. Coreflood tests revealed that polymer retention, which was mainly caused by mechanical entrapment, was higher in cores that had laminations parallel to the direction of flow than in cores that had crossbed laminae. In cores that had crossbed laminae, polymer retention increased with an increase in the lamination angle. Retained polymer is harmful to the stability of fluid front in cores that have laminations parallel to the direction of flow, but is helpful in cores that have crossbed laminae.

  7. Coupled actin-lamin biopolymer networks and protecting DNA

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Rocklin, D. Zeb; Mao, Xiaoming; Schwarz, J. M.

    The mechanical properties of cells are largely determined by networks of semiflexible biopolymers forming the cytoskeleton. Similarly, the mechanical properties of cell nuclei are also largely determined by networks of semiflexible biopolymers forming the nuclear cytoskeleton. In particular, a network of filamentous lamin sits just inside the inner nuclear membrane to presumably protect the heart of the cell nucleus--the DNA. It has been demonstrated over the past decade that the actin cytoskeletal biopolymer network and the lamin biopolymer network are coupled via a sequence of proteins bridging the outer and inner nuclear membranes, known as the LINC complex. We, therefore, probe the consequences of such a coupling in a model biopolymer network system via numerical simulations to understand the resulting deformations in the lamin network in response to perturbations in the actin cytoskeletal network. We find, for example, that the force transmission across the coupled system can depend sensitively on the concentration of LINC complexes. Such study could have implications for mechanical mechanisms of the regulation of transcription since DNA couples to lamin via lamin-binding domains so that deformations in the lamin network may result in deformations in the DNA.

  8. The assembly of C. elegans lamins into macroscopic fibers.

    PubMed

    Zingerman-Koladko, Irena; Khayat, Maayan; Harapin, Jan; Shoseyov, Oded; Gruenbaum, Yosef; Salman, Ahmad; Medalia, Ohad; Ben-Harush, Kfir

    2016-10-01

    Intermediate filament (IF) proteins are known mainly by their propensity to form viscoelastic filamentous networks within cells. In addition, IF-proteins are essential parts of various biological materials, such as horn and hagfish slime threads, which exhibit a range of mechanical properties from hard to elastic. These properties and their self-assembly nature made IF-proteins attractive building blocks for biomimetic and biological materials in diverse applications. Here we show that a type V IF-protein, the Caenorhabditis elegans nuclear lamin (Ce-lamin), is a promising building block for protein-based fibers. Electron cryo-tomography of vitrified sections enabled us to depict the higher ordered assembly of the Ce-lamin into macroscopic fibers through the creation of paracrystalline fibers, which are prominent in vitro structures of lamins. The lamin fibers respond to tensile force as other IF-protein-based fibers, i.e., hagfish slime threads, and possess unique mechanical properties that may potentially be used in certain applications. The self-assembly nature of lamin proteins into a filamentous structure, which is further assembled into a complex network, can be easily modulated. This knowledge may lead to a better understanding of the relationship in IF-proteins-based fibers and materials, between their hierarchical structures and their mechanical properties. PMID:27341289

  9. Tracer Lamination in the Stratosphere: A Global Climatology

    NASA Technical Reports Server (NTRS)

    Appenzeller, Christof; Holton, James R.

    1997-01-01

    Vertical soundings of stratospheric ozone often exhibit laminated tracer structures characterized by strong vertical tracer gradients. The change in time of these gradients is used to define a tracer lamination rate. It is shown that this quantity can be calculated by the cross product of the horizontal temperature and horizontal tracer gradients. A climatology based on UARS satellite-borne ozone data and on ozone-like pseudotracer data is presented. Three stratospheric regions with high lamination rates were found: the part of the stratospheric overworld which is influenced by the polar vortex, the part of the lowermost stratosphere which is influenced by the tropopause and a third region in the subtropical lower stratosphere mainly characterized with strong vertical shear. High lamination rates in the stratospheric overworld were absent during summer, whereas in the lowermost stratosphere high lamination rates were found year-round. This is consistent with the occurrence and seasonal variation of the horizontal tracer gradient and vertical shear necessary for tilting the tracer surfaces. During winter, high lamination rates associated with the stratospheric polar vortex are present down to approximately 100 hPa. Several features of the derived climatology are roughly consistent with earlier balloon-borne studies. The patterns in the southern and northern hemisphere are comparable, but details differ as anticipated from a less disturbed and more symmetric southern polar vortex.

  10. Properties of wheat gluten/poly(lactic acid) laminates.

    PubMed

    Cho, Sung-Woo; Gällstedt, Mikael; Hedenqvist, Mikael S

    2010-06-23

    Laminates of compression-molded glycerol-plasticized wheat gluten (WG) films surrounded and supported by poly(lactic acid) (PLA) films have been produced and characterized. The objective was to obtain a fully renewable high gas barrier film with sufficient mechanical integrity to function in, for example, extrusion-coating paper/board applications. It was shown that the lamination made it possible to make films with a broad range of glycerol contents (0-30 wt %) with greater strength than single unsupported WG films. The low plasticizer contents yielded laminates with very good oxygen barrier properties. In addition, whereas the unsupported WG films had an immeasurably high water vapor transmission rate (WVTR), the laminate showed values that were finite and surprisingly, in several cases, also lower than that of PLA. Besides being a mechanical support (as evidenced by bending and tensile data) and a shield between the WG and surrounding moisture, the PLA layer also prevented the loss of the glycerol plasticizer from the WG layer. This was observed after the laminate had been aged on an "absorbing" blotting paper for up to 17 weeks. The interlayer adhesion (peel strength) decreased with decreasing glycerol content and increasing WG film molding temperature (130 degrees C instead of 110 degrees C). The latter effect was probably due to a higher protein aggregation, as revealed by infrared spectroscopy. The lamination temperature (110-140 degrees C) did not, however, have a major effect on the final peel strength. PMID:20504031

  11. Bending Boundary Layers in Laminated-Composite Circular Cylindrical Shells

    NASA Technical Reports Server (NTRS)

    Nemeth, Michael P.; Smeltzer, Stanley S., III

    2000-01-01

    An analytical, parametric study of the attenuation of bending boundary layers or edge effects in balanced and unbalanced, symmetrically and unsymmetrically laminated thin cylindrical shells is presented for nine contemporary material systems. The analysis is based on the linear Sanders-Koiter shell equations and specializations to the Love-Kirchhoff shell equations and Donnell's equations are included. Two nondimensional parameters are identified that characterize and quantify the effects of laminate orthotropy and laminate anisotropy on the bending boundary-layer decay length in a very general and encompassing manner. A substantial number of structural design technology results are presented for a wide range of laminated-composite cylinders. For all the laminate constructions considered, the results show that the differences between results that were obtained with the Sanders-Koiter shell equations, the Love-Kirchhoff shell equations, and Donnell's equations are negligible. The results also show that the effect of anisotropy in the form of coupling between pure bending and twisting has a negligible effect on the size of the bending boundary-layer decay length of the balanced, symmetrically laminated cylinders considered. Moreover, the results show that coupling between the various types of shell anisotropies has a negligible effect on the calculation of the bending boundary-layer decay length in most cases. The results also show that in some cases neglecting the shell anisotropy results in underestimating the bending boundary-layer decay length and in other cases it results in an overestimation.

  12. Higher order finite element analysis of thick composite laminates

    NASA Technical Reports Server (NTRS)

    Goering, J.; Kim, H. J.

    1992-01-01

    A higher order, sub-parametric, laminated, 3D solid finite element was used for the analysis of very thick laminated composite plates. The geometry of this element is defined by four nodes in the X-Y plane which define a prism of material through the thickness of the laminate. There are twenty-four degrees of freedom at each node; translations at the upper and lower surfaces of the laminate in each of the three coordinate directions, and the derivatives of these translations with respect to each coordinate. This choice of degrees of freedom leads to displacement and strain compatibility at the corners. Stacking sequence effects are accounted for by explicitly integrating the strain energy density through the thickness of the element. The laminated solid element was combined with a gap-contact element to analyze thick laminated composite lugs loaded through flexible pins. The resulting model accounts for pin bending effects that produce non-uniform bearing stresses through the thickness of the lug. A thick composite lug experimental test program was performed, and provided data that was used to validate the analytical model. Two lug geometries and three stacking sequences were tested.

  13. B-type lamins in health and disease☆

    PubMed Central

    Hutchison, C.J.

    2014-01-01

    For over two decades, B-type lamins were thought to have roles in fundamental processes including correct assembly of nuclear envelopes, DNA replication, transcription and cell survival. Recent studies have questioned these roles and have instead emphasised the role of these proteins in tissue building and tissue integrity, particularly in tissues devoid of A-type lamins. Other studies have suggested that the expression of B-type lamins in somatic cells influences the rate of entry into states of cellular senescence. In humans duplication of the LMNB1 gene (encoding lamin B1) causes an adult onset neurodegenerative disorder, termed autosomal dominant leukodystrophy, whilst very recently, LMNB1 has been implicated as a susceptibility gene in neural tube defects. This is consistent with studies in mice that reveal a critical role for B-type lamins in neuronal migration and brain development. In this review, I will consider how different model systems have contributed to our understanding of the functions of B-type lamins and which of those functions are critical for human health and disease. PMID:24380701

  14. Three dimensional inelastic finite element analysis of laminated composites

    NASA Technical Reports Server (NTRS)

    Griffin, O. H., Jr.; Kamat, M. P.

    1980-01-01

    Formulations of the inelastic response of laminated composites to thermal and mechanical loading are used as the basis for development of the computer NALCOM (Nonlinear Analysis of Laminated Composites) computer program which uses a fully three dimensional isoparametric finite element with 24 nodes and 72 degrees of freedom. An incremental solution is performed with nonlinearities introduced as pseudoloads computed for initial strains. Equilibrium iteration may be performed at every step. Elastic and elastic-plastic response of boron/epoxy and graphite/epoxy graphite/epoxy and problems of curing 0/90 sub s Gr/Ep laminates with and without circular holes are analyzed. Mechanical loading of + or - 45sub s Gr/Ep laminates is modeled and symmetry conditions which exist in angle-ply laminates are discussed. Results are compared to experiments and other analytical models when possible. All models are seen to agree reasonably well with experimetnal results for off-axis tensile coupons. The laminate analyses show the three dimensional effects which are present near holes and free corners.

  15. Nuclear localization signal deletion mutants of lamin A and progerin reveal insights into lamin A processing and emerin targeting.

    PubMed

    Wu, Di; Flannery, Andrew R; Cai, Helen; Ko, Eunae; Cao, Kan

    2014-01-01

    Lamin A is a major component of the lamina, which creates a dynamic network underneath the nuclear envelope. Mutations in the lamin A gene (LMNA) cause severe genetic disorders, one of which is Hutchinson-Gilford progeria syndrome (HGPS), a disease triggered by a dominant mutant named progerin. Unlike the wild-type lamin A, whose farnesylated C-terminus is excised during post-translational processing, progerin retains its farnesyl tail and accumulates on the nuclear membrane, resulting in abnormal nuclear morphology during interphase. In addition, membrane-associated progerin forms visible cytoplasmic aggregates in mitosis. To examine the potential effects of cytoplasmic progerin, nuclear localization signal (NLS) deleted progerin and lamin A (PGΔNLS and LAΔNLS, respectively) have been constructed. We find that both ΔNLS mutants are farnesylated in the cytosol and associate with a sub-domain of the ER via their farnesyl tails. While the farnesylation on LAΔNLS can be gradually removed, which leads to its subsequent release from the ER into the cytoplasm, PGΔNLS remains permanently farnesylated and membrane-bounded. Moreover, both ΔNLS mutants dominantly affect emerin's nuclear localization. These results reveal new insights into lamin A biogenesis and lamin A-emerin interaction. PMID:24637396

  16. Nuclear localization signal deletion mutants of lamin A and progerin reveal insights into lamin A processing and emerin targeting

    PubMed Central

    Wu, Di; Flannery, Andrew R; Cai, Helen; Ko, Eunae; Cao, Kan

    2014-01-01

    Lamin A is a major component of the lamina, which creates a dynamic network underneath the nuclear envelope. Mutations in the lamin A gene (LMNA) cause severe genetic disorders, one of which is Hutchinson-Gilford progeria syndrome (HGPS), a disease triggered by a dominant mutant named progerin. Unlike the wild-type lamin A, whose farnesylated C-terminus is excised during post-translational processing, progerin retains its farnesyl tail and accumulates on the nuclear membrane, resulting in abnormal nuclear morphology during interphase. In addition, membrane-associated progerin forms visible cytoplasmic aggregates in mitosis. To examine the potential effects of cytoplasmic progerin, nuclear localization signal (NLS) deleted progerin and lamin A (PGΔNLS and LAΔNLS, respectively) have been constructed. We find that both ΔNLS mutants are farnesylated in the cytosol and associate with a sub-domain of the ER via their farnesyl tails. While the farnesylation on LAΔNLS can be gradually removed, which leads to its subsequent release from the ER into the cytoplasm, PGΔNLS remains permanently farnesylated and membrane-bounded. Moreover, both ΔNLS mutants dominantly affect emerin’s nuclear localization. These results reveal new insights into lamin A biogenesis and lamin A-emerin interaction. PMID:24637396

  17. Progressive Fracture of Laminated Composite Stiffened Plate

    NASA Technical Reports Server (NTRS)

    Gotsis, Pascalis K.; Chamis, Christos C.; David, Kostantinos; Abdi, Frank

    2007-01-01

    Laminated fiber-reinforced composite stiffened plate with [0/90/plus or minus 45]s plies made of S-Glass/epoxy are evaluated via computational simulation to study damage and fracture progression. The loads are pressure and temperature which varies from 21 to 65.5 C (case I) and from 143.3 to 21 C (case II). An integrated computer code is used for the simulation of the damage progression. Results show that damage initiation begins at low load level, with matrix cracking at the 0 deg. (bottom and top) plies, fiber fracture at the bottom (0 deg.) ply and interply delamination at the top (0 deg. ) ply. Increasing the applied pressure, the damage growth is expended resulting in fracture through the thickness of the structure. At this stage, 90 percent of the plies damage at applied pressure 15.306 MPa for the case I and 15.036 MPa for the case II. After this stage the cracks propagate rapidly and the structure collapses.

  18. Benefits of oxygen incorporation in atomic laminates

    NASA Astrophysics Data System (ADS)

    Dahlqvist, Martin

    2016-04-01

    Atomic laminates such as MAX phases benefit from the addition of oxygen in many ways, from the formation of a protective oxide surface layer with self-healing capabilities when cracks form to the tuning of anisotropic conductivity. In this paper oxygen incorporation and vacancy formation in M 2AlC (M  =  Ti, V, Cr) MAX phases have been studied using first-principles calculations where the focus is on phase stability and electronic structure for different oxygen and/or vacancy configurations. Oxygen prefers different lattice sites depending on M-element and this can be correlated to the number of available non-bonding M d-electrons. In Ti2AlC, oxygen substitutes carbon while in Cr2AlC it is located interstitially within the Al-layer. I predict that oxygen incorporation in Ti2AlC stabilizes the material, which explains the experimentally observed 12.5 at% oxygen (x  =  0.5) in Ti2Al(C1‑x O x ). In addition, it is also possible to use oxygen to stabilize the hypothetical Zr2AlC and Hf2AlC. Hence, oxygen incorporation may be beneficial in many ways. Not only can it make a material more stable, but it also can act as a reservoir for internal self-healing with shorter diffusion paths.

  19. Energy-efficient steels for motor laminations

    NASA Astrophysics Data System (ADS)

    Werner, F. E.; Jaffee, R. I.

    1992-03-01

    Motors use over 60% of all electricity generated, and their losses exceed 200 × 109 kW.hr/year. A significant part of this loss results from eddy currents and hysteretic processes in the motor laminations. These so- called core losses cost motor users about 3 × 109/year. The metallurgy and economics of using various steels are considered, with emphasis on 5- to 125- hp polyphase induction motors. A lower core loss steel, even though it is more expensive, is economically justified most of the time when the operating costs of motors are considered. Impurities must be minimized, and steels can now be made with the principal impurities being less than 30 ppm. Further reduction of core losses depends on using the best steel processing equipment available, production of a consistently low carbon content so that decarburizing during the final anneal can be eliminated, developing a better understanding of the relation between material properties and performance in motors, and an increased willingness by the motor users to pay more for better motors that are cheaper to own in the long run.

  20. Damage growth in composite laminates with interleaves

    NASA Technical Reports Server (NTRS)

    Goree, James G.

    1987-01-01

    The influence of placing interleaves between fiber reinforced plies in multilayered composite laminates is investigated. The geometry of the composite is idealized as two dimensional, isotropic, linearly elastic media made of a damaged layer bonded between two half planes and separated by thin interleaves of low extensional and shear moduli. The damage in the layer is taken in the form of a symmetric crack perpendicular to the interface and may extend up to the interface. The case of an H-shaped crack in the form of a broken layer with delamination along the interface is also analyzed. The interleaves are modeled as distributed shear and tension springs. Fourier integral transform techniques are used to develop solutions in terms of singular integral equations. An asymptotic analysis of the integral equations based on Muskhelishvili's techniques reveals logarithmically singular axial stresses in the half plane at the crack tips for the broken layer. For the H shaped crack, similar singularities are found to exist in the axial stresses at the interface crack tips in the layer and the half plane. The solution of the equations is found numerically for the stresses and displacements by using the Hadamard's concept of direct differentiation of Cauchy integrals as well as Gaussian integration techniques.

  1. Interface fracture and composite deformation of model laminates

    NASA Astrophysics Data System (ADS)

    Fox, Matthew R.

    Model laminates were studied to improve the understanding of composite mechanical behavior. NiAl/Mo and NiAl/Cr model laminates, with a series of interfaces, were bonded at 1100°C. Reaction layers were present in all laminates, varying in thickness with bonding conditions. Interface fracture strengths and resistances were determined under primarily mode II loading conditions using a novel technique, the asymmetrically-loaded shear (ALS) test, in which one layer of the laminate was loaded in compression, producing a stable interface crack. The NiAl/Mo interface was also fractured in four-point bending. A small amount of plasticity was found to play a role in crack initiation. During steady-state mode II interface fracture of NiAl/Mo model laminates, large-scale slip was observed near the crack tip in the NiAl adjacent to the interface. After testing, the local slope and curvature of the interface were characterized at intervals along the interface and at slip locations to qualitatively describe local stresses present at and just ahead of the crack tip. The greatest percentage of slip occurred where closing forces on the crack tip were below the maximum value and were decreasing with crack growth. A mechanism for crack propagation is presented describing the role of large-scale slip in crack propagation. The mechanical response of structural laminates in 3-D stress states, as would be present in a polycrystalline aggregate composed of lamellar grains, are lacking. In order to understand the response of laminates composed of hard and soft phases, Pb/Zn laminates were prepared and tested in compression with varying lamellar orientation relative to the loading axis. A model describing the mechanical response in a general state assuming elastic-perfectly plastic isotropic layers was developed. For the 90° laminate, a different approach was applied, using the friction hill concepts used in forging analyses. With increasing ratios of cross-sectional radius to layer

  2. Testing and simulation of composite laminates under impact loading

    NASA Astrophysics Data System (ADS)

    Dang, Xinglai

    Owing to their high stiffness-to-weight and high strength-to-weight ratios, fiber-reinforced polymer-matrix composite laminates are excellent materials for high-performance structures. However, their properties in the thickness direction are very poor as they are weakly bonded by polymeric matrices through laminate interfaces. Accordingly, when a composite laminate is subjected to impact loading, high interlaminar stresses along with the low interlaminar strengths could easily result in interlaminar damage such as delamination. This thesis investigated the response of composite laminates under low-velocity impact and presented numerical techniques for impact simulation. To begin with, instrumented drop-weight impacts ranging from subperforation to perforation levels were introduced to composite laminates having various dimensions and thicknesses. Damaged composite laminates were then subjected to compression-after-impact tests for evaluations of residual properties. Experimental results revealed that perforation was an important damage milestone since impact parameters such as peak force, contact duration, maximum deflection and energy absorption, and residual properties such as compressive stiffness, strength and energy absorption all reached critical levels as perforation took place. It was also found that thickness played a more important role than in-plane dimensions in perforation process. In order to understand more about the relationship between laminate thickness and perforation resistance and to present an economical method to improve perforation resistance, thick laminated composite plates and their assembled counterparts were investigated and compared. An energy profile correlating the impact energy and absorbed energy at all energy levels for each type of composite plates investigated was established and found to be able to address the relationship between energy and damage. Experimental results concluded that increasing thickness was more efficient

  3. Tape cast bioactive metal-ceramic laminates for structural application

    NASA Astrophysics Data System (ADS)

    Clupper, Daniel Christopher

    Bioglass 45S5, is a silica based glass which is able to rapidly form strong bonds with bone and soft tissue in vivo. It is used clinically to replace damaged ear ossicles and in dental surgery to help maintain the structural integrity of the jaw bone. The goal of the research was to demonstrate that Bioglass can be toughened by lamination with metallic layers while maintaining bioactivity. Improvement of the mechanical properties of Bioglass 45SS would allow for additional clinical applications, such as fracture fixation plates, or vertebral spacers. Bioglass 45S5 was tape cast and laminated with clinically relevant metals (316L, stainless steel and titanium) as well as copper in an effort to demonstrate that the effective toughness, or area under the load-deflection diagram can be increased significantly through ductile layer lamination. The average strength of monolithic tape cast sintered Bioglass was as high as 150 MPa and the toughness measured approximately 1.0 MPa m1/2. Copper-Bioglass laminates clearly demonstrated the toughening effect of metal layers on tape cast sintered Bioglass 45S5. Steel-Bioglass laminates, although less tough than the copper-Bioglass laminates, showed higher strengths. In vitro bioactivity tests of both titanium and steel Bioglass laminates showed the formation of mature and thick hydroxyapatite layers after 24 hours in Tris buffer solution. Under the standard test conditions, the bioactivity of monolithic tape cast sintered Bioglass increased with increasing sintering temperature. For samples sintered at 1000°C, thick crystalline layers of hydroxyapatite formed within 24 hours in Tris buffer solution. The bioactivity of these samples approached that of amorphous bulk Bioglass. Samples processed at 800°C were able to form thick crystalline hydroxyapatite layer after 24 hours when the test solution volume was increased by eight times.

  4. Crush testing, characterizing, and modeling the crashworthiness of composite laminates

    NASA Astrophysics Data System (ADS)

    Garner, David Michael, Jr.

    Research in the field of crashworthiness of composite materials is presented. A new crush test method was produced to characterize the crush behavior of composite laminates. In addition, a model of the crush behavior and a method for rank ordering the energy absorption capability of various laminates were developed. The new crush test method was used for evaluating the crush behavior of flat carbon/epoxy composite specimens at quasi-static and dynamic rates. The University of Utah crush test fixture was designed to support the flat specimen against catastrophic buckling. A gap, where the specimen is unsupported, allowed unhindered crushing of the specimen. In addition, the specimen's failure modes could be clearly observed during crush testing. Extensive crush testing was conducted wherein the crush force and displacement data were collected to calculate the energy absorption, and high speed video was captured during dynamic testing. Crush tests were also performed over a range of fixture gap heights. The basic failure modes were buckling, crack growth, and fracture. Gap height variations resulted in poorly, properly, and overly constrained specimens. In addition, guidelines for designing a composite laminate for crashworthiness were developed. Modeling of the crush behavior consisted of the delamination and fracture of a single ply or group of like plies during crushing. Delamination crack extension was modeled using the mode I energy release rate, G lc, where an elastica approach was used to obtain the strain energy. Variations in Glc were briefly explored with double cantilever beam tests wherein crack extension occurred along a multidirectional ply interface. The model correctly predicted the failure modes for most of the test cases, and offered insight into how the input parameters affect the model. The ranking method related coefficients of the laminate and sublaminate stiffness matrices, the ply locations within the laminate, and the laminate thickness. The

  5. Dynamic Stability of Uncertain Laminated Beams Under Subtangential Loads

    NASA Technical Reports Server (NTRS)

    Goyal, Vijay K.; Kapania, Rakesh K.; Adelman, Howard (Technical Monitor); Horta, Lucas (Technical Monitor)

    2002-01-01

    Because of the inherent complexity of fiber-reinforced laminated composites, it can be challenging to manufacture composite structures according to their exact design specifications, resulting in unwanted material and geometric uncertainties. In this research, we focus on the deterministic and probabilistic stability analysis of laminated structures subject to subtangential loading, a combination of conservative and nonconservative tangential loads, using the dynamic criterion. Thus a shear-deformable laminated beam element, including warping effects, is derived to study the deterministic and probabilistic response of laminated beams. This twenty-one degrees of freedom element can be used for solving both static and dynamic problems. In the first-order shear deformable model used here we have employed a more accurate method to obtain the transverse shear correction factor. The dynamic version of the principle of virtual work for laminated composites is expressed in its nondimensional form and the element tangent stiffness and mass matrices are obtained using analytical integration The stability is studied by giving the structure a small disturbance about an equilibrium configuration, and observing if the resulting response remains small. In order to study the dynamic behavior by including uncertainties into the problem, three models were developed: Exact Monte Carlo Simulation, Sensitivity Based Monte Carlo Simulation, and Probabilistic FEA. These methods were integrated into the developed finite element analysis. Also, perturbation and sensitivity analysis have been used to study nonconservative problems, as well as to study the stability analysis, using the dynamic criterion.

  6. Increasing ferromagnetic resonance frequency using lamination and shape

    NASA Astrophysics Data System (ADS)

    El-Ghazaly, A.; White, R. M.; Wang, S. X.

    2015-05-01

    The magnetic permeability frequency spectrum is one of the most critical properties for the operation of high frequency magnetic devices in the gigahertz regime. Permeability is fairly constant up to the ferromagnetic resonance (FMR) frequency, at which point the relative permeability drops to unity. Extending FMR to higher frequencies is thus imperative for developing GHz-range magnetic devices. The simulation and experimental investigations presented in this paper demonstrate how stacking layers to form a laminated film increases the FMR frequency by allowing flux closure between layers along the induced easy-axis direction. This flux closure reduces the demagnetization factor along the easy-axis direction by two orders of magnitude. This effect, however, is only observable in patterned films where the shape anisotropy is enough to result in variation of the FMR frequency. Experiments using patterned magnetic cores were performed to illustrate this effect. Through detailed investigation of the permeability spectra of both single layer and laminated CoTaZr magnetic films patterned into 500 μm × L films (where L ranged from 200 μm to 1000 μm), the FMR frequency was extracted and proven to increase as a result of lamination. The degree to which the frequency is boosted by lamination increases exponentially as the length of the film is decreased. Through a combination of lamination and shape demagnetization, the effective anisotropy, which directly relates to FMR frequency, was shown to increase by about 100%.

  7. Fracture behavior of unidirectional boron/aluminum composite laminates

    NASA Technical Reports Server (NTRS)

    Goree, J. G.; Jones, W. F.

    1983-01-01

    An experiment was conducted to verify the results of mathematical models which predict the stresses and displacements of fibers and the amount of damage growth in a center-notched lamina as a function of the applied remote stress and the matrix and fiber material properties. A brittle lacquer coating was used to detect the yielding in the matrix while X-ray techniques were used to determine the number of broken fibers in the laminate. The notched strengths and the amounts of damage found in the specimens agree well with those predicted by the mathematical model. It is shown that the amount of damage and the crack opening displacement does not depend strongly on the number of plies in the laminate for a given notch width. By heat-treating certain laminates to increase the yield stress of the alumina matrix, the effect of different matrix properties on the fracture behavior was investigated. The stronger matrix is shown to weaken the notched laminate by decreasing the amount of matrix damage, thereby making the laminate more notch sensitive.

  8. Tunable characteristics of bending resonance frequency in magnetoelectric laminated composites

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Li, Ping; Wen, Yu-Mei; Zhu, Yong

    2013-07-01

    As the magnetoelectric (ME) effect in piezoelectric/magnetostrictive laminated composites is mediated by mechanical deformation, the ME effect is significantly enhanced in the vicinity of resonance frequency. The bending resonance frequency (fr) of bilayered Terfenol-D/PZT (MP) laminated composites is studied, and our analysis predicts that (i) the bending resonance frequency of an MP laminated composite can be tuned by an applied dc magnetic bias (Hdc) due to the ΔE effect; (ii) the bending resonance frequency of the MP laminated composite can be controlled by incorporating FeCuNbSiB layers with different thicknesses. The experimental results show that with Hdc increasing from 0 Oe (1 Oe=79.5775 A/m) to 700 Oe, the bending resonance frequency can be shifted in a range of 32.68 kHz <= fr <= 33.96 kHz. In addition, with the thickness of the FeCuNbSiB layer increasing from 0 μm to 90 μm, the bending resonance frequency of the MP laminated composite gradually increases from 33.66 kHz to 39.18 kHz. This study offers a method of adjusting the strength of dc magnetic bias or the thicknesses of the FeCuNbSiB layer to tune the bending resonance frequency for ME composite, which plays a guiding role in the ME composite design for real applications.

  9. Bending Boundary Layers in Laminated-Composite Circular Cylindrical Shells

    NASA Technical Reports Server (NTRS)

    Nemeth, Michael P.; Smeltzer, Stanley S., III

    2000-01-01

    A study of the attenuation of bending boundary layers in balanced and unbalanced, symmetrically and unsymmetrically laminated cylindrical shells is presented for nine contemporary material systems. The analysis is based on the linear Sanders-Koiter shell equations and specializations to the Love-Kirchhoff shell equations and Donnell's equations are included. Two nondimensional parameters are identified that characterize the effects of laminate orthotropy and anisotropy on the bending boundary-layer decay length in a very general manner. A substantial number of structural design technology results are presented for a wide range of laminated-composite cylinders. For all laminates considered, the results show that the differences between results obtained with the Sanders-Koiter shell equations, the Love-Kirchhoff shell equations, and Donnell's equations are negligible. The results also show that the effect of anisotropy in the form of coupling between pure bending and twisting has a negligible effect on the size of the bending boundary-layer decay length of the balanced, symmetrically laminated cylinders considered. Moreover, the results show that coupling between the various types of shell anisotropies has a negligible effect on the calculation of the bending boundary-layer decay length in most cases. The results also show that, in some cases, neglecting the shell anisotropy results in underestimating the bending boundary-layer decay length and, in other cases, results in an overestimation.

  10. In vitro evidence for a bacterial pathogenesis of equine laminitis.

    PubMed

    Mungall, B A; Kyaw-Tanner, M; Pollitt, C C

    2001-04-01

    Utilizing an in vitro laminitis explant model, we have investigated how bacterial broth cultures and purified bacterial proteases activate matrix metalloproteinases (MMPs) and alter structural integrity of cultured equine lamellar hoof explants. Four Gram-positive Streptococcus spp. and three Gram-negative bacteria all induced a dose-dependent activation of MMP-2 and MMP-9 and caused lamellar explants to separate. MMP activation was deemed to have occurred if a specific MMP inhibitor, batimastat, blocked MMP activity and prevented lamellar separation. Thermolysin and streptococcal pyrogenic exotoxin B (SpeB) both separated explants dose-dependently but only thermolysin was inhibitable by batimastat or induced MMP activation equivalent to that seen with bacterial broths. Additionally, thermolysin and broth MMP activation appeared to be cell dependent as MMP activation did not occur in isolation. These results suggest the rapid increase in streptococcal species in the caecum and colon observed in parallel with carbohydrate induced equine laminitis may directly cause laminitis via production of exotoxin(s) capable of activating resident MMPs within the lamellar structure. Once activated, these MMPs can degrade key components of the basement membrane (BM) hemidesmosome complex, ultimately separating the BM from the epidermal basal cells resulting in the characteristic laminitis histopathology of hoof lamellae. While many different causative agents have been evaluated in the past, the results of this study provide a unifying aetiological mechanism for the development of carbohydrate induced equine laminitis. PMID:11240100