Fiber-reinforced ceramic composites for Earth-to-orbit rocket engine turbines

NASA Technical Reports Server (NTRS)

Brockmeyer, Jerry W.; Schnittgrund, Gary D.

1990-01-01

Fiber reinforced ceramic matrix composites (FRCMC) are emerging materials systems that offer potential for use in liquid rocket engines. Advantages of these materials in rocket engine turbomachinery include performance gain due to higher turbine inlet temperature, reduced launch costs, reduced maintenance with associated cost benefits, and reduced weight. This program was initiated to assess the state of FRCMC development and to propose a plan for their implementation into liquid rocket engine turbomachinery. A complete range of FRCMC materials was investigated relative to their development status and feasibility for use in the hot gas path of earth-to-orbit rocket engine turbomachinery. Of the candidate systems, carbon fiber-reinforced silicon carbide (C/SiC) offers the greatest near-term potential. Critical hot gas path components were identified, and the first stage inlet nozzle and turbine rotor of the fuel turbopump for the liquid oxygen/hydrogen Space Transportation Main Engine (STME) were selected for conceptual design and analysis. The critical issues associated with the use of FRCMC were identified. Turbine blades were designed, analyzed and fabricated. The Technology Development Plan, completed as Task 5 of this program, provides a course of action for resolution of these issues.

[Time-evolution study on the cation exchange in the process of reinforcing slip soil by laser-induced breakdown spectroscopy].

PubMed

Liu, Lu-Wen; Zeng, Wei-Li; Zhu, Xiang-Fei; Wu, Jin-Quan; Lin, Zhao-Xiang

2014-03-01

In the present paper, the time evolution study on slip soils treated by different proportions of ionic soil stabilizer (ISS) water solution was conducted by the LIBS system and the relationship between the cation exchange and such engineering properties of reinforcing soil as plasticity index, cohesive force and coefficient of compressibility were analyzed. The results showed that the cation exchange velocity of the proportion of 1:200 ISS reinforcing soil is the fastest among the three proportions (1:100, 1:200 and 1:300) and the modification effect of engineering performance index is quite obvious. These studies provide an experimental basis for the ISS applied to curing project, and monitoring geotechnical engineering performance by LIBS technology also provides a new way of thinking for the curing project monitoring.

Corrosion detection and evolution monitoring in reinforced concrete structures by the use of fiber Bragg grating sensor

NASA Astrophysics Data System (ADS)

Ali-Alvarez, S.; Ferdinand, P.; Magne, S.; Nogueira, R. P.

2013-04-01

Corrosion of reinforced bar (rebar) in concrete structures represents a major issue in civil engineering works, being its detection and evolution a challenge for the applied research. In this work, we present a new methodology to corrosion detection in reinforced concrete structures, by combining Fiber Bragg Grating (FBG) sensors with the electrochemical and physical properties of rebar in a simplified assembly. Tests in electrolytic solutions and concrete were performed for pitting and general corrosion. The proposed Structural Health Monitoring (SHM) methodology constitutes a direct corrosion measurement potentially useful to implement or improve Condition-Based Maintenance (CBM) program for civil engineering concrete structures.

Improving System Engineering Excellence at NASA's Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Takada, Pamela Wallace; Newton, Steve; Gholston, Sampson; Thomas, Dale (Technical Monitor)

2001-01-01

NASA's Marshall Space Flight Center (MSFC) management feels that sound system engineering practices are essential for successful project management, NASA studies have concluded that recent project failures could be attributed in part to inadequate systems engineering. A recent survey of MSFC project managers and system engineers' resulted in the recognition of a need for training in Systems Engineering Practices, particularly as they relate to MSFC projects. In response to this survey, an internal pilot short-course was developed to reinforce accepted practices for system engineering at MSFC. The desire of the MSFC management is to begin with in-house training and offer additional educational opportunities to reinforce sound system engineering principles to the more than 800 professionals who are involved with system engineering and project management. A Systems Engineering Development Plan (SEDP) has been developed to address the longer-term systems engineering development needs of MSFC. This paper describes the survey conducted and the training course that was developed in response to that survey.

77 FR 34073 - Value Engineering

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-08

... OFFICE OF MANAGEMENT AND BUDGET Office of Federal Procurement Policy Value Engineering AGENCY... Office of Management and Budget Circular No. A-131, ``Value Engineering''. SUMMARY: The Office of Federal...- 131, Value Engineering, to update and reinforce policies associated with the consideration and use of...

Numerical modeling of interaction of the aircraft engine with concrete protective structures

NASA Astrophysics Data System (ADS)

Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.

2018-01-01

The paper presents numerical modeling results considering interaction of Boeing 747 aircraft engine with nuclear power station protective shell. Protective shell has been given as a reinforced concrete structure with complex scheme of reinforcement. The engine has been simulated by cylinder projectile made from titanium alloy. The interaction velocity has comprised 180 m/s. The simulation is three-dimensional solved by finite element method using the author’s own software package EFES. Fracture and fragmentation of materials have been considered in calculations. Program software has been assessed to be used in calculation of multiple-contact objectives.

78 FR 78399 - Value Engineering

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-26

... OFFICE OF MANAGEMENT AND BUDGET Office of Federal Procurement Policy Value Engineering AGENCY... to Office of Management and Budget Circular No. A-131, ``Value Engineering''. SUMMARY: The Office of... revisions to OMB Circular A-131, Value Engineering, to update and reinforce policies associated with the...

Inorganic Polymer Matrix Composite Strength Related to Interface Condition

PubMed Central

Radford, Donald W.; Grabher, Andrew; Bridge, John

2009-01-01

Resin transfer molding of an inorganic polymer binder was successfully demonstrated in the preparation of ceramic fiber reinforced engine exhaust valves. Unfortunately, in the preliminary processing trials, the resulting composite valves were too brittle for in-engine evaluation. To address this limited toughness, the effectiveness of a modified fiber-matrix interface is investigated through the use of carbon as a model material fiber coating. After sequential heat treatments composites molded from uncoated and carbon-coated fibers are compared using room temperature 3-point bend testing. Carbon-coated Nextel fiber reinforced geopolymer composites demonstrated a 50% improvement in strength, versus that of the uncoated fiber reinforced composites, after the 250 °C postcure.

Geosynthetic Reinforced Soil Integrated Bridge System, Synthesis Report

DOT National Transportation Integrated Search

2011-01-01

This report is the second in a two-part series to provide engineers with the necessary background knowledge of Geosynthetic Reinforced Soil (GRS) technology and its fundamental characteristics as an alternative to other construction methods. It suppl...

Strength and stiffness of reinforced rectangular columns under biaxially eccentric thrust.

DOT National Transportation Integrated Search

1976-01-01

Compression tests on nine reinforced concrete rectangular columns subjected to : constant thrust and biaxially eccentric moments were conducted at the off-campus : research facility of The University of Texas, The Civil Engineering Structures : Labor...

Finite element modeling and analysis of reinforced-concrete bridge.

DOT National Transportation Integrated Search

2000-09-01

Despite its long history, the finite element method continues to be the predominant strategy employed by engineers to conduct structural analysis. A reliable method is needed for analyzing structures made of reinforced concrete, a complex but common ...

Women's Reasons for Leaving the Engineering Field.

PubMed

Fouad, Nadya A; Chang, Wen-Hsin; Wan, Min; Singh, Romila

2017-01-01

Among the different Science, Technology, Engineering, and Math fields, engineering continues to have one of the highest rates of attrition (Hewlett et al., 2008). The turnover rate for women engineers from engineering fields is even higher than for men (Frehill, 2010). Despite increased efforts from researchers, there are still large gaps in our understanding of the reasons that women leave engineering. This study aims to address this gap by examining the reasons why women leave engineering. Specifically, we analyze the reasons for departure given by national sample of 1,464 women engineers who left the profession after having worked in the engineering field. We applied a person-environment fit theoretical lens, in particular, the Theory of Work Adjustment (TWA) (Dawis and Lofquist, 1984) to understand and categorize the reasons for leaving the engineering field. According to the TWA, occupations have different "reinforcer patterns," reflected in six occupational values, and a mismatch between the reinforcers provided by the work environment and individuals' needs may trigger departure from the environment. Given the paucity of literature in this area, we posed research questions to explore the reinforcer pattern of values implicated in women's decisions to leave the engineering field. We used qualitative analyses to understand, categorize, and code the 1,863 statements that offered a glimpse into the myriad reasons that women offered in describing their decisions to leave the engineering profession. Our results revealed the top three sets of reasons underlying women's decision to leave the jobs and engineering field were related to: first, poor and/or inequitable compensation, poor working conditions, inflexible and demanding work environment that made work-family balance difficult; second, unmet achievement needs that reflected a dissatisfaction with effective utilization of their math and science skills, and third, unmet needs with regard to lack of recognition at work and adequate opportunities for advancement. Implications of these results for future research as well as the design of effective intervention programs aimed at women engineers' retention and engagement in engineering are discussed.

Advanced rotary engine components utilizing fiber reinforced Mg castings

NASA Technical Reports Server (NTRS)

Goddard, D.; Whitman, W.; Pumphrey, R.; Lee, C.-M.

1986-01-01

Under a two-phase program sponsored by NASA, the technology for producing advanced rotary engine components utilizing graphite fiber-reinforced magnesium alloy casting is being developed. In Phase I, the successful casting of a simulated intermediate housing was demonstrated. In Phase II, the goal is to produce an operating rotor housing. The effort involves generation of a material property data base, optimization of parameters, and development of wear- and corrosion-resistant cast surfaces and surface coatings. Results to date are described.

Three-Dimensional Material Properties of Composites with S2-Glass Fibers or Ductile Hybrid Fabric

DTIC Science & Technology

2013-01-13

RDECOM-TARDEC 6501 E. Eleven Mile Rd. Warren, MI 48397-5000 ABSTRACT Material properties were determined for fiber - reinforced polymers (FRPs) with...Research Development and Engineering Center (TARDEC) funded a research project to determine the mechanical properties of seven fiber reinforced ...Approved for public release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT Material properties were determined for fiber - reinforced

Orthorhombic Titanium Matrix Composite Subjected to Simulated Engine Mission Cycles

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.

1997-01-01

Titanium matrix composites (TMC's) are commonly made up of a titanium alloy matrix reinforced by silicon carbide fibers that are oriented parallel to the loading axis. These composites can provide high strength at lower densities than monolithic titanium alloys and superalloys in selected gas turbine engine applications. The use of TMC rings with unidirectional SiC fibers as reinforcing rings within compressor rotors could significantly reduce the weight of these components. In service, these TMC reinforcing rings would be subjected to complex service mission loading cycles, including fatigue and dwell excursions. Orthorhombic titanium aluminide alloys are of particular interest for such TMC applications because their tensile and creep strengths are high in comparison to those of other titanium alloys. The objective of this investigation was to assess, in simulated mission tests at the NASA Lewis Research Center, the durability of a SiC (SCS-6)/Ti-22Al-23Nb (at.%) TMC for compressor ring applications, in cooperation with the Allison Engine Company.

Design Guide for glass fiber reinforced metal pressure vessel

NASA Technical Reports Server (NTRS)

Landes, R. E.

1973-01-01

Design Guide has been prepared for pressure vessel engineers concerned with specific glass fiber reinforced metal tank design or general tank tradeoff study. Design philosophy, general equations, and curves are provided for safelife design of tanks operating under anticipated space shuttle service conditions.

9. Photocopy of Reinforced Concrete Details drawing (from the BPA ...

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

9. Photocopy of Reinforced Concrete Details drawing (from the BPA Engineering Vault, Drawing C13-J2-342-D1, Sheet 6, 13 March 1939) - Bonneville Power Administration South Bank Substation, I-84, South of Bonneville Dam Powerhouse, Bonneville, Multnomah County, OR

Reinforced Portland cement porous scaffolds for load-bearing bone tissue engineering applications.

PubMed

Higuita-Castro, Natalia; Gallego-Perez, Daniel; Pelaez-Vargas, Alejandro; García Quiroz, Felipe; Posada, Olga M; López, Luis E; Sarassa, Carlos A; Agudelo-Florez, Piedad; Monteiro, Fernando J; Litsky, Alan S; Hansford, Derek J

2012-02-01

Modified Portland cement porous scaffolds with suitable characteristics for load-bearing bone tissue engineering applications were manufactured by combining the particulate leaching and foaming methods. Non-crosslinked polydimethylsiloxane was evaluated as a potential reinforcing material. The scaffolds presented average porosities between 70 and 80% with mean pore sizes ranging from 300 μm up to 5.0 mm. Non-reinforced scaffolds presented compressive strengths and elastic modulus values of 2.6 and 245 MPa, respectively, whereas reinforced scaffolds exhibited 4.2 and 443 MPa, respectively, an increase of ∼62 and 80%. Portland cement scaffolds supported human osteoblast-like cell adhesion, spreading, and propagation (t = 1-28 days). Cell metabolism and alkaline phosphatase activity were found to be enhanced at longer culture intervals (t ≥ 14 days). These results suggest the possibility of obtaining strong and biocompatible scaffolds for bone repair applications from inexpensive, yet technologically advanced materials such as Portland cement. Copyright © 2011 Wiley Periodicals, Inc.

Bioinspired, Graphene/Al2O3 Doubly Reinforced Aluminum Composites with High Strength and Toughness.

PubMed

Zhang, Yunya; Li, Xiaodong

2017-11-08

Nacre, commonly referred to as nature's armor, has served as a blueprint for engineering stronger and tougher bioinspired materials. Nature organizes a brick-and-mortar-like architecture in nacre, with hard bricks of aragonite sandwiched with soft biopolymer layers. However, cloning nacre's entire reinforcing mechanisms in engineered materials remains a challenge. In this study, we employed hybrid graphene/Al 2 O 3 platelets with surface nanointerlocks as hard bricks for primary load bearer and mechanical interlocking, along with aluminum laminates as soft mortar for load distribution and energy dissipation, to replicate nacre's architecture and reinforcing effects in aluminum composites. Compared with aluminum, the bioinspired, graphene/Al 2 O 3 doubly reinforced aluminum composite demonstrated an exceptional, joint improvement in hardness (210%), strength (223%), stiffness (78%), and toughness (30%), which are even superior over nacre. This design strategy and model material system should guide the synthesis of bioinspired materials to achieve exceptionally high strength and toughness.

Fighting Corrosion

NASA Technical Reports Server (NTRS)

2004-01-01

Reinforced concrete structures such as bridges, parking decks, and balconies are designed to have a service life of over 50 years. All too often, however, many structures fall short of this goal, requiring expensive repairs and protection work earlier than anticipated. The corrosion of reinforced steel within the concrete infrastructure is a major cause for this premature deterioration. Such corrosion is a particularly dangerous problem for the facilities at NASA s Kennedy Space Center. Located near the Atlantic Ocean in Florida, Kennedy is based in one of the most corrosive-prone areas in the world. In order to protect its launch support structures, highways, pipelines, and other steel-reinforced concrete structures, Kennedy engineers developed the Galvanic Liquid Applied Coating System. The system utilizes an inorganic coating material that slows or stops the corrosion of reinforced steel members inside concrete structures. Early tests determined that the coating meets the criteria of the National Association of Corrosion Engineers for complete protection of steel rebar embedded in concrete. Testing is being continued at the Kennedy's Materials Science Beach Corrosion Test Site.

1. Photocopy of engineering drawing (original in the Office of ...

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

1. Photocopy of engineering drawing (original in the Office of the Cuyahoga County Engineer)--1907 NORTH ROCKY RIVER BRIDGE--PROPOSED DESIGN--REINFORCED CONCRETE: AN ALTERNATIVE DESIGN FOR THE DETROIT AVENUE CROSSING - Rocky River Bridge, Spanning Beaver Dam River, Rocky River, Cuyahoga County, OH

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.

Design of reinforcement welding machine within steel framework for marine engineering

NASA Astrophysics Data System (ADS)

Wang, Gang; Wu, Jin

2017-04-01

In this project, a design scheme that reinforcement welding machine is added within the steel framework is proposed according to the double-side welding technology for box-beam structure in marine engineering. Then the design and development of circuit and transmission mechanism for new welding equipment are completed as well with one sample machine being made. Moreover, the trial running is finished finally. Main technical parameters of the equipment are: the working stroke: ≥1500mm, the welding speed: 8˜15cm/min and the welding sheet thickness: ≥20mm.

Reducing the Surface Performance Requirements of a Primary Mirror by Adding a Deformable Mirror in its Optical Path

DTIC Science & Technology

2015-12-01

carbon fiber reinforced polymer (CFRP) mirrors been proposed for use in future imaging satellites. Compared to traditional glass -based mirrors, CFRP...SUBJECT TERMS carbon fiber reinforced polymer mirror, adaptive optics, deformable mirror, surface figure error 15. NUMBER OF PAGES 79 16. PRICE CODE...Department of Mechanical and Aerospace Engineering iv THIS PAGE INTENTIONALLY LEFT BLANK v ABSTRACT In recent years, carbon fiber reinforced

Development of advanced grid stiffened (AGS) fiber reinforced polymer (FRP) tube-encased concrete columns : [technical summary].

DOT National Transportation Integrated Search

2013-03-01

In recent years, the use of fi ber reinforced polymer (FRP) tube-encased concrete columns for new construction and rebuilding : of engineering structures has increased. The purpose in FRP tube-encased concrete columns is to replace the steel rebar by...

Application of fiber-reinforced bismaleimide materials to aircraft nacelle structures

NASA Technical Reports Server (NTRS)

Peros, Vasilios; Ruth, John; Trawinski, David

1992-01-01

Existing aircraft engine nacelle structures employ advanced composite materials to reduce weight and thereby increase overall performance. Use of advanced composite materials on existing aircraft nacelle structures includes fiber-reinforced epoxy structures and has typically been limited to regions furthest away from the hot engine core. Portions of the nacelle structure that are closer to the engine require materials with a higher temperature capability. In these portions, existing nacelle structures employ aluminum sandwich construction and skin/stringer construction. The aluminum structure is composed of many detail parts and assemblies and is usually protected by some form of ablative, insulator, or metallic thermal shield. A one-piece composite inner cowl for a new-generation engine nacelle structure has been designed using fiber-reinforced bismaleimide (BMI) materials and honeycomb core in a sandwich construction. The new composite design has many advantages over the existing aluminum structure. Multiple details were integrated into the one-piece composite design, thereby significantly reducing the number of detail parts and fasteners. The use of lightweight materials and the reduction of the number of joints result in a significant weight reduction over the aluminum design; manufacturing labor and the overall number of tools required have also been reduced. Several significant technical issues were addressed in the development of a BMI composite design. Technical evaluation of the available BMI systems led to the selection of a toughened BMI material which was resistant to microcracking under thermal cyclic loading and enhanced the damage tolerance of the structure. Technical evaluation of the degradation of BMI materials in contact with aluminum and other metals validated methods for isolation of the various materials. Graphite-reinforced BMI in contact with aluminum and some steels was found to degrade in salt spray testing. Isolation techniques such as those used for graphite-reinforced epoxy structures were shown to provide adequate protection. The springback and producibility of large BMI structures were evaluated by manufacturing prototype hardware which had the full-scale cross section of the one-piece composite structure.

Women’s Reasons for Leaving the Engineering Field

PubMed Central

Fouad, Nadya A.; Chang, Wen-Hsin; Wan, Min; Singh, Romila

2017-01-01

Among the different Science, Technology, Engineering, and Math fields, engineering continues to have one of the highest rates of attrition (Hewlett et al., 2008). The turnover rate for women engineers from engineering fields is even higher than for men (Frehill, 2010). Despite increased efforts from researchers, there are still large gaps in our understanding of the reasons that women leave engineering. This study aims to address this gap by examining the reasons why women leave engineering. Specifically, we analyze the reasons for departure given by national sample of 1,464 women engineers who left the profession after having worked in the engineering field. We applied a person-environment fit theoretical lens, in particular, the Theory of Work Adjustment (TWA) (Dawis and Lofquist, 1984) to understand and categorize the reasons for leaving the engineering field. According to the TWA, occupations have different “reinforcer patterns,” reflected in six occupational values, and a mismatch between the reinforcers provided by the work environment and individuals’ needs may trigger departure from the environment. Given the paucity of literature in this area, we posed research questions to explore the reinforcer pattern of values implicated in women’s decisions to leave the engineering field. We used qualitative analyses to understand, categorize, and code the 1,863 statements that offered a glimpse into the myriad reasons that women offered in describing their decisions to leave the engineering profession. Our results revealed the top three sets of reasons underlying women’s decision to leave the jobs and engineering field were related to: first, poor and/or inequitable compensation, poor working conditions, inflexible and demanding work environment that made work-family balance difficult; second, unmet achievement needs that reflected a dissatisfaction with effective utilization of their math and science skills, and third, unmet needs with regard to lack of recognition at work and adequate opportunities for advancement. Implications of these results for future research as well as the design of effective intervention programs aimed at women engineers’ retention and engagement in engineering are discussed. PMID:28713295

Carbon nanotubes reinforced chitosan films: mechanical properties and cell response of a novel biomaterial for cardiovascular tissue engineering.

PubMed

Kroustalli, A; Zisimopoulou, A E; Koch, S; Rongen, L; Deligianni, D; Diamantouros, S; Athanassiou, G; Kokozidou, M; Mavrilas, D; Jockenhoevel, S

2013-12-01

Carbon nanotubes have been proposed as fillers to reinforce polymeric biomaterials for the strengthening of their structural integrity to achieve better biomechanical properties. In this study, a new polymeric composite material was introduced by incorporating various low concentrations of multiwalled carbon nanotubes (MWCNTs) into chitosan (CS), aiming at achieving a novel composite biomaterial with superior mechanical and biological properties compared to neat CS, in order to be used in cardiovascular tissue engineering applications. Both mechanical and biological characteristics in contact with the two relevant cell types (endothelial cells and vascular myofibroblasts) were studied. Regarding the mechanical behavior of MWCNT reinforced CS (MWCNT/CS), 5 and 10 % concentrations of MWCNTs enhanced the mechanical behavior of CS, with that of 5 % exhibiting a superior mechanical strength compared to 10 % concentration and neat CS. Regarding biological properties, MWCNT/CS best supported proliferation of endothelial and myofibroblast cells, MWCNTs and MWCNT/CS caused no apoptosis and were not toxic of the examined cell types. Conclusively, the new material could be suitable for tissue engineering (TE) and particularly for cardiovascular TE applications.

Teaching Reinforcement of Stochastic Behavior Using Monte Carlo Simulation.

ERIC Educational Resources Information Center

Fox, William P.; And Others

1996-01-01

Explains a proposed block of instruction that would give students in industrial engineering, operations research, systems engineering, and applied mathematics the basic understanding required to begin more advanced courses in simulation theory or applications. (DDR)

Missouri S&T formula electric racing.

DOT National Transportation Integrated Search

2014-05-01

The Formula Electric racing team will promote Missouri S&Ts engineering excellence by successfully competing against other top : engineering universities in the US and around the world. Students on the team will have the opportunity to reinforce t...

Experimental Investigation on Thermal Physical Properties of an Advanced Glass Fiber Composite Material

NASA Astrophysics Data System (ADS)

Guangfa, Gao; Yongchi, Li; Zheng, Jing; Shujie, Yuan

Fiber reinforced composite materials were applied widely in aircraft and space vehicles engineering. Aimed to an advanced glass fiber reinforced composite material, a series of experiments for measuring thermal physical properties of this material were conducted, and the corresponding performance curves were obtained through statistic analyzing. The experimental results showed good consistency. And then the thermal physical parameters such as thermal expansion coefficient, engineering specific heat and sublimation heat were solved and calculated. This investigation provides an important foundation for the further research on the heat resistance and thermodynamic performance of this material.

Overview of ORNL/NRC programs addressing durability of concrete structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naus, D.J.; Oland, C.B.

1994-06-01

The role of reinforced concrete relative to its applications as either safety-related structures in nuclear power or engineered barriers of low-level radioactive waste disposal facilities is described. Factors that can affect the long-term durability of reinforced concrete are identified. Overviews are presented of the Structural Aging Program, which is addressing the aging management of safety-related concrete structures in nuclear power plants, and the Permeability Test Methods and Data Program, which is identifying pertinent data and information for use in performance assessments of engineered barriers for low-level radioactive waste disposal.

Development of Improved Environmental Resistant Organic-Reinforced Materials Systems

DTIC Science & Technology

1975-11-01

Advanced composites , graphite and boron reinforced laminates, moisture resistance, environmental resistance, organic matrix composites . 20. ABSTRACT...in November 1975 for publication. Efforts at TOD were conducted within the Advanced Composites Engineering Departmfntrunde; L technical...weight makes^organic matrix advanced composites hardware extremely attractive for today s modern Air Force weapons systems. Accordingly, such

An Australian Study of Generic Competencies Required by Engineers

ERIC Educational Resources Information Center

Male, S. A.; Bush, M. B.; Chapman, E. S.

2011-01-01

Engineering curricula have expanded in recent decades. In addition to science and technical engineering, they now include several non-technical competencies. This is a trend reinforced by programme accreditation. The authors take the viewpoint that it is important to ensure that graduates have the competencies they will require for their work. The…

The raft foundation reinforcement construction technology of Hongyun Building B tower

NASA Astrophysics Data System (ADS)

Liu, Yu; Yin, Suhua; Wu, Yanli; Zhao, Ying

2017-08-01

The foundation of Hongyun building B tower is made of raft board foundation which is 3300mm in the thickness include four kinds of reinforcement Φ32, Φ28, Φ12 and 12 steel grade two, in respective. It is researched that the raft foundation mass concrete construction technology is expatiated from temperature and cracks of the raft foundation and the temperature control and monitoring of the concrete base slab construction and concrete curing. According to the characteristics with large volume and thickness of the engineering of raft foundation, the construction of the reinforced force was calculated and the quality control measures were used to the reinforcement binding and connection, so it is success that Hongyun Building B tower raft foundation reinforced construction.

Engineering on the straight and narrow: the mechanics of nanofibrous assemblies for fiber-reinforced tissue regeneration.

PubMed

Mauck, Robert L; Baker, Brendon M; Nerurkar, Nandan L; Burdick, Jason A; Li, Wan-Ju; Tuan, Rocky S; Elliott, Dawn M

2009-06-01

Tissue engineering of fibrous tissues of the musculoskeletal system represents a considerable challenge because of the complex architecture and mechanical properties of the component structures. Natural healing processes in these dense tissues are limited as a result of the mechanically challenging environment of the damaged tissue and the hypocellularity and avascular nature of the extracellular matrix. When healing does occur, the ordered structure of the native tissue is replaced with a disorganized fibrous scar with inferior mechanical properties, engendering sites that are prone to re-injury. To address the engineering of such tissues, we and others have adopted a structurally motivated approach based on organized nanofibrous assemblies. These scaffolds are composed of ultrafine polymeric fibers that can be fabricated in such a way to recreate the structural anisotropy typical of fiber-reinforced tissues. This straight-and-narrow topography not only provides tailored mechanical properties, but also serves as a 3D biomimetic micropattern for directed tissue formation. This review describes the underlying technology of nanofiber production and focuses specifically on the mechanical evaluation and theoretical modeling of these structures as it relates to native tissue structure and function. Applying the same mechanical framework for understanding native and engineered fiber-reinforced tissues provides a functional method for evaluating the utility and maturation of these unique engineered constructs. We further describe several case examples where these principles have been put to test, and discuss the remaining challenges and opportunities in forwarding this technology toward clinical implementation.

Engineering on the Straight and Narrow: The Mechanics of Nanofibrous Assemblies for Fiber-Reinforced Tissue Regeneration

PubMed Central

Baker, Brendon M.; Nerurkar, Nandan L.; Burdick, Jason A.; Li, Wan-Ju; Tuan, Rocky S.; Elliott, Dawn M.

2009-01-01

Tissue engineering of fibrous tissues of the musculoskeletal system represents a considerable challenge because of the complex architecture and mechanical properties of the component structures. Natural healing processes in these dense tissues are limited as a result of the mechanically challenging environment of the damaged tissue and the hypocellularity and avascular nature of the extracellular matrix. When healing does occur, the ordered structure of the native tissue is replaced with a disorganized fibrous scar with inferior mechanical properties, engendering sites that are prone to re-injury. To address the engineering of such tissues, we and others have adopted a structurally motivated approach based on organized nanofibrous assemblies. These scaffolds are composed of ultrafine polymeric fibers that can be fabricated in such a way to recreate the structural anisotropy typical of fiber-reinforced tissues. This straight-and-narrow topography not only provides tailored mechanical properties, but also serves as a 3D biomimetic micropattern for directed tissue formation. This review describes the underlying technology of nanofiber production and focuses specifically on the mechanical evaluation and theoretical modeling of these structures as it relates to native tissue structure and function. Applying the same mechanical framework for understanding native and engineered fiber-reinforced tissues provides a functional method for evaluating the utility and maturation of these unique engineered constructs. We further describe several case examples where these principles have been put to test, and discuss the remaining challenges and opportunities in forwarding this technology toward clinical implementation. PMID:19207040

Carbon Fiber Reinforced Carbon Composite Valve for an Internal Combustion Engine

NASA Technical Reports Server (NTRS)

Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

1999-01-01

A carbon fiber reinforced carbon composite valve for internal combustion engines and the like formed of continuous carbon fibers throughout the valve's stem and head is disclosed. The valve includes braided carbon fiber material over axially aligned unidirectional carbon fibers forming a valve stem; the braided and unidirectional carbon fibers being broomed out at one end of the valve stem forming the shape of the valve head; the valve-shaped structure being densified and rigidized with a matrix of carbon containing discontinuous carbon fibers: and the finished valve being treated to resist oxidation. Also disclosed is a carbon matrix plug containing continuous and discontinuous carbon fibers and forming a net-shape valve head acting as a mandrel over which the unidirectional and braided carbon fibers are formed according to textile processes. Also disclosed are various preform valves and processes for making finished and preform carbon fiber reinforced carbon composite valves.

Interim Report on the Investigation of the Fresh Properties of Synthetic Fiber-Reinforced Concrete for the Richardson Landing Casting Field

DTIC Science & Technology

2017-04-01

nation’s toughest engineering and environmental challenges. ERDC develops innovative solutions in civil and military engineering , geospatial sciences... civil engineer , Concrete and Materials Branch CEERD-GM-C Kirk Walker 601.634.3237 Kirk.E.Walker@usace.army.mil Engineering technician, Concrete...2017 Approved for public release; distribution is unlimited. The U.S. Army Engineer Research and Development Center (ERDC) solves the

Development of Specifications for Engineered Cementitious Composites for Use in Bridge Deck Overlays

DOT National Transportation Integrated Search

2016-02-01

Engineered cementitious composite (ECC) material is a high strength, fiber-reinforced, ductile mortar mixture that can exhibit tensile strains of up to 5%. ECC has a dense matrix, giving the material exceptional durability characteristics. The durabi...

Liquid rocket engine fluid-cooled combustion chambers

NASA Technical Reports Server (NTRS)

1972-01-01

A monograph on the design and development of fluid cooled combustion chambers for liquid propellant rocket engines is presented. The subjects discussed are (1) regenerative cooling, (2) transpiration cooling, (3) film cooling, (4) structural analysis, (5) chamber reinforcement, and (6) operational problems.

Recent development in blast performance of fiber-reinforced concrete

NASA Astrophysics Data System (ADS)

Hajek, R.; Foglar, M.; Kohoutkova, A.

2017-09-01

The paper presents an overview of the recent development in blast performance of fiber reinforced concrete. The paper builds on more than ten years’ history of the research in this field by the team of the Department of Concrete and Masonry Structures of the Faculty of Civil Engineering of the Czech Technical University in Prague.

Leveraging Quiz-Based Multiple-Prize Web Tournaments for Reinforcing Routine Mathematical Skills

ERIC Educational Resources Information Center

Gonzalez-Tablas, Ana I.; de Fuentes, Jose M.; Hernandez-Ardieta, Jorge L.; Ramos, Benjamin

2013-01-01

In Higher Education Engineering studies, there exists the need of engaging students in performing drill and practice activities with the goal of reinforcing routine mathematical skills. The usual optionality of these tasks entails the risk of students not fulfilling them in an effective way. Although competitive approaches are not a trend in…

77 FR 65840 - Section 610 Reviews of Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-31

... and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements; NESHAP: Reinforced Plastic... Requirements (Heavy-Duty 610 Review); NESHAP: Reinforced Plastic Composites Production (Plastics 610 Review...-0313 (for the Heavy-Duty 610 Review), Docket ID No. EPA-HQ- OAR-2012-0816 (for the Plastics 610 Review...

Smart timber bridge on geosynthetic reinforced soil (GRS) abutments

Treesearch

Adam Senalik; James P. Wacker; Travis K. Hosteng; John Hermanson

2017-01-01

Recently, Buchanan County, Iowa, has cooperated with the U.S. Federal Highway Administration (FHWA), USDA Forest Service, Forest Products Laboratory (FPL), and Iowa State University’s Bridge Engineering Center (ISU–BEC) to initiate a project involving the construction and monitoring of a glued-laminated (glulam) timber superstructure on geosynthetic reinforced soil (...

Lincoln Advanced Science and Engineering Reinforcement

DTIC Science & Technology

1989-01-01

Chamblee Physics Lincoln University Kelvin Clark Physics Lincoln University Dwayne Cole Mechanical Engineering Howard University Francis Countiss Physics...Mathematics Lincoln University Spencer Lane Mechanical Engineering Howard University Edward Lawerence Physics Lincoln University Cyd Hall Actuarial Science...Pittsburgh Lloyd Hammond Ph.D., Bio-Chemistry Purdue University Timothy Moore M.S., Psychology Howard University * completedI During 1988, three (3

Value engineering and cost effectiveness of various fiber reinforced polymer (FRP) repair systems.

DOT National Transportation Integrated Search

2006-06-01

Seventeen 40 year old C-Channel type prestressed concrete bridge girders and one impact damaged AASHTO : Type II prestressed concrete girder were tested under static and fatigue loading to determine the cost-effectiveness : and value engineering aspe...

Carbon Fiber Reinforced Carbon Composites Rotary Valves for Internal Combustion Engines

NASA Technical Reports Server (NTRS)

Northam, G. Burton (Inventor); Ransone, Philip O. (Inventor); Rivers, H. Kevin (Inventor)

1999-01-01

Carbon fiber reinforced carbon composite rotary, sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or warp-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties, do not present the sealing and lubrication problems that have prevented rotary, sleeve, and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

Higher-Order Theory for Functionally Graded Materials

NASA Technical Reports Server (NTRS)

Aboudi, J.; Pindera, M. J.; Arnold, Steven M.

2001-01-01

Functionally graded materials (FGM's) are a new generation of engineered materials wherein the microstructural details are spatially varied through nonuniform distribution of the reinforcement phase(s). Engineers accomplish this by using reinforcements with different properties, sizes, and shapes, as well as by interchanging the roles of the reinforcement and matrix phases in a continuous manner (ref. 1). The result is a microstructure that produces continuously or discretely changing thermal and mechanical properties at the macroscopic or continuum scale. This new concept of engineering the material's microstructure marks the beginning of a revolution both in the materials science and mechanics of materials areas since it allows one, for the first time, to fully integrate the material and structural considerations into the final design of structural components. Functionally graded materials are ideal candidates for applications involving severe thermal gradients, ranging from thermal structures in advanced aircraft and aerospace engines to computer circuit boards. Owing to the many variables that control the design of functionally graded microstructures, full exploitation of the FGM's potential requires the development of appropriate modeling strategies for their response to combined thermomechanical loads. Previously, most computational strategies for the response of FGM's did not explicitly couple the material's heterogeneous microstructure with the structural global analysis. Rather, local effective or macroscopic properties at a given point within the FGM were first obtained through homogenization based on a chosen micromechanics scheme and then subsequently used in a global thermomechanical analysis.

Fiber-reinforced plastic composites. Possibilities and limitations of applications as machine-construction materials

NASA Technical Reports Server (NTRS)

Ophey, Lothar

1988-01-01

The use of fiber-reinforced composite structural materials in engineering applications is discussed in a survey of currently available technology and future prospects. The ongoing rapid growth in the use of these materials is described, and the criteria to be applied in selecting base materials, lamination schemes, fasteners, and processing methods are examined in detail and illustrated with graphs, diagrams, flow charts, and drawings. A description of a sample application (comparing the properties of steel, CFRP, SiC-reinforced Al, CFRP/steel, and CFRP/Al automobile piston rods) is included.

Ethical considerations for a better collaboration between architects and structural engineers: design of buildings with reinforced concrete frame systems in earthquake zones.

PubMed

Hurol, Yonca

2014-06-01

Architects design building structures, although structural design is the profession of structural engineers. Thus, it is better for architects and structural engineers to collaborate starting from the initial phases of the architectural design. However, this is not very common because of the contradictory design processes and value systems held within the two professions. This article provides a platform upon which architects and structural engineers can resolve the value conflicts between them by analysing phases of the structural design of reinforced concrete frame systems in architecture, the criteria of the structural design for each phase and determining the conflicting values for each criterion. The results shown in the article demonstrate that the architectural design of structures is a complex process, which is based on contradictory values and value systems. Finally, the article suggests to architects and structural engineers to use Value Sensitive Design and to choose an appropriate team leader in order to resolve the unethical conflict between them and to avoid any unreasonable decision making.

An experiment on the use of disposable plastics as a reinforcement in concrete beams

NASA Technical Reports Server (NTRS)

Chowdhury, Mostafiz R.

1992-01-01

Illustrated here is the concept of reinforced concrete structures by the use of computer simulation and an inexpensive hands-on design experiment. The students in our construction management program use disposable plastic as a reinforcement to demonstrate their understanding of reinforced concrete and prestressed concrete beams. The plastics used for such an experiment vary from plastic bottles to steel reinforced auto tires. This experiment will show the extent to which plastic reinforcement increases the strength of a concrete beam. The procedure of using such throw-away plastics in an experiment to explain the interaction between the reinforcement material and concrete, and a comparison of the test results for using different types of waste plastics are discussed. A computer analysis to simulate the structural response is used to compare the test results and to understand the analytical background of reinforced concrete design. This interaction of using computers to analyze structures and to relate the output results with real experimentation is found to be a very useful method for teaching a math-based analytical subject to our non-engineering students.

Fiber reinforced sandy slopes under groundwater return flow

USDA-ARS?s Scientific Manuscript database

The instability of natural hillslopes, riverbanks and engineered embankments due to seepage has been a major concern. In an effort to prevent failures, tension resisting synthetic fibers may be an effective additive to increase the mechanical properties of engineered soils. In this study, triaxial c...

Chemical Engineering Data Analysis Made Easy with DataFit

ERIC Educational Resources Information Center

Brenner, James R.

2006-01-01

The outline for half of a one-credit-hour course in analysis of chemical engineering data is presented, along with a range of typical problems encountered later on in the chemical engineering curriculum that can be used to reinforce the data analysis skills learned in the course. This mini course allows students to be exposed to a variety of ChE…

Tensile properties of nicalon fiber-reinforced carbon following aerospace turbine engine testing

NASA Astrophysics Data System (ADS)

Pierce, J. L.; Zawada, L. P.; Srinivasan, R.

2003-06-01

The durability of coated Nicalon silicon carbide fiber-reinforced carbon (SiC/C) as the flap and seal exhaust nozzle components in a military aerospace turbine engine was studied. Test specimens machined from both a flap and a seal component were tested for residual strength following extended ground engine testing on a General Electric F414 afterburning turbofan engine. Although small amounts of damage to the protective exterior coating were identified on each component following engine testing, the tensile strengths were equal to the as-fabricated tensile strength of the material. Differences in strength between the two components and variability within the data sets could be traced back to the fabrication process using witness coupon test data from the manufacturer. It was also observed that test specimens machined transversely across the flap and seal components were stronger than those machined along the length. The excellent retained strength of the coated SiC/C material after extended exposure to the severe environment in the afterburner exhaust section of an aerospace turbofan engine has resulted in this material being selected as the baseline material for the F414 exhaust nozzle system.

Technology Base Enhancement Program. Metal Matrix Composites

DTIC Science & Technology

1993-08-30

efficiency, improved structural reliability, and reduced maintenance when compared to carbon fiber reinforced composites . Aerospace engines (in particular...different materials. The composite consists of a metal matrix reinforced with particulates, flakes, whiskers,3 continuous fibers , filaments, wires, or...graphite and carbon to metals. They come in three general forms: particulates (or particles) with a length to diameter ratio of about 1; chopped fibers or

Machine Learning Control For Highly Reconfigurable High-Order Systems

DTIC Science & Technology

2015-01-02

develop and flight test a Reinforcement Learning based approach for autonomous tracking of ground targets using a fixed wing Unmanned...Reinforcement Learning - based algorithms are developed for learning agents’ time dependent dynamics while also learning to control them. Three algorithms...to a wide range of engineering- based problems . Implementation of these solutions, however, is often complicated by the hysteretic, non-linear,

Weaving multi-layer fabrics for reinforcement of engineering components

NASA Technical Reports Server (NTRS)

Hill, B. J.; Mcilhagger, R.; Mclaughlin, P.

1993-01-01

The performance of interlinked, multi-layer fabrics and near net shape preforms for engineering applications, woven on a 48 shaft dobby loom using glass, aramid, and carbon continuous filament yarns is assessed. The interlinking was formed using the warp yarns. Two basic types of structure were used. The first used a single warp beam and hence each of the warp yarns followed a similar path to form four layer interlinked reinforcements and preforms. In the second two warp beams were used, one for the interlinking yarns which pass from the top to the bottom layer through-the-thickness of the fabric and vice versa, and the other to provide 'straight' yarns in the body of the structure to carry the axial loading. Fabrics up to 15mm in thickness were constructed with varying amounts of through-the-thickness reinforcement. Tapered T and I sections were also woven, with the shaping produced by progressive removal of ends during construction. These fabrics and preforms were impregnated with resin and cured to form composite samples for testing. Using these two basic types of construction, the influence of reinforcement construction and the proportion and type of interlinking yarn on the performance of the composite was assessed.

Characterization and processing of heat treated aluminium matrix composite

NASA Astrophysics Data System (ADS)

Doifode, Yogesh; Kulkarni, S. G.

2018-05-01

The present study is carried out to determine density and porosity of Aluminium bagasse ash reinforced composite produced by powder metallurgy method. Bagasse ash is used as reinforcement material having high silica and alumina contents and varied from 5 weight % to 40 weight%. The manufactured composite is heat treated, the main objective of heat treatment is to prepare the material structurally and physically fit for engineering application. The results showed that the density decreases with percentage increase in reinforcement of bagasse ash from 2.6618 gm/cm3 to 1.9830 gm/cm3 with the minimum value at 40 weight% bagasse ash without heat treatment whereas after heat treatment density of composite increases due filling up of voids and porous holes. Heat treatment processing is the key to this improvement, with the T6 heat treated composite to convene the reduced porosity of composite. Consequently aluminium metal matrix composite combines the strength of the reinforcement to achieve a combination of desirable properties not available in any single material. It may observe that porosity in case of powder metallurgy samples showed more porosity portions compare to the casting samples. In order to achieve optimality in structure and properties of Bagasse ash-reinforcement heat treatment techniques have evolved. Generally, the ceramic reinforcements increase the density of the base alloy during fabrication of composites. However, the addition of lightweight reinforcements reduces the density of the hybrid composites. The results also showed that, the density varies from to with minimum value at 40 wt. % BA. The results of the statistical analysis showed that there are significant differences among the means of each property of the composites at various levels of BA replacement .It was concluded that bagasse ash can be used as reinforcement and the produced composites have low density and heat treatment reduces porosity which could be used in automobile industry for the production of engine parts.

Inquiry-Based Pre-Engineering Activities for K-4 Students

ERIC Educational Resources Information Center

Perrin, Michele

2004-01-01

This paper uses inquiry-based learning to introduce primary students to the concepts and terminology found in four introductory engineering courses: Differential Equations, Circuit Analysis, Thermodynamics, and Dynamics. Simple electronic sensors coupled with everyday objects, such as a troll doll, demonstrate and reinforce the physical principles…

An engineering approach for the application of textile composites to a structural component

NASA Technical Reports Server (NTRS)

Baldwin, Jack W.; Gracias, Brian K.; Clark, Steven R.

1993-01-01

An engineering approach for the application of textile composites to a structural component is addressed. The main objective is to improve impact resistance of composite blades by using some form of 3-D reinforcement. Project goals, results, and conclusions are discussed.

Carbon Fiber Reinforced Carbon Composite Rotary Valve for an Internal Combustion Engine

NASA Technical Reports Server (NTRS)

Northam, G.Burton (Inventor); Ransone, Philip O. (Inventor); Rivers, H. Kevin (Inventor)

2000-01-01

Carbon fiber reinforced carbon composite rotary sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or wrap-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties do not present the sealing and lubrication problems that have prevented rotary sleeve and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

Design of rapid hardening engineered cementitious composites for sustainable construction

NASA Astrophysics Data System (ADS)

Marushchak, Uliana; Sanytsky, Myroslav; Sydor, Nazar

2017-12-01

This paper deals with design of environmentally friendly Rapid Hardening Engineered Cementitious Composite (RHECC) nanomodified with ultrafine mineral additives, polycarboxylate ether based superplasticizer, calcium hydrosilicate nanoparticles and dispersal reinforced by fibers. The incremental coefficient of surface activity was proposed in order to estimation of ultrafine supplementary materials (fly ash, methakaolin, microsilica) efficiency. A characterization of RHECC's compressive and flexural properties at different ages is reported in this paper. Early compressive strength of ECC is 45-50 MPa, standard strength - 84-95 MPa and parameter Rc2/Rc28 - 65-70%. The microstructure of the cement matrix and RHECC was investigated. The use of ultrafine mineral supplementary materials provides reinforcement of structure on micro- and nanoscale level (cementing matrix) due to formation of sub-microreinforcing hydrate phase as AFt- and C-S-H phases in unclinker part of cement matrix, resulting in the phenomena of "self-reinforcement" on the microstructure level. Designed RHECC may be regarded as lower brittle since the crack resistance coefficient is higher comparison to conventional fine grain concrete.

Compressive Properties of Metal Matrix Syntactic Foams in Free and Constrained Compression

NASA Astrophysics Data System (ADS)

Orbulov, Imre Norbert; Májlinger, Kornél

2014-06-01

Metal matrix syntactic foam (MMSF) blocks were produced by an inert gas-assisted pressure infiltration technique. MMSFs are advanced hollow sphere reinforced-composite materials having promising application in the fields of aviation, transport, and automotive engineering, as well as in civil engineering. The produced blocks were investigated in free and constrained compression modes, and besides the characteristic mechanical properties, their deformation mechanisms and failure modes were studied. In the tests, the chemical composition of the matrix material, the size of the reinforcing ceramic hollow spheres, the applied heat treatment, and the compression mode were considered as investigation parameters. The monitored mechanical properties were the compressive strength, the fracture strain, the structural stiffness, the fracture energy, and the overall absorbed energy. These characteristics were strongly influenced by the test parameters. By the proper selection of the matrix and the reinforcement and by proper design, the mechanical properties of the MMSFs can be effectively tailored for specific and given applications.

Perspectives Of Employment Of Pultruded FRP Structural Elements In Seismic Engineering Field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russo, Salvatore; Silvestri, Mirko

2008-07-08

Today the employment of FRP material in structural engineering is in common use, with excellent results in term of applications especially as reinforcement of existing structures. This success is related to the very reduced weight of FRP material, to its performance in term of strength and durability and thanks to the easy use in technical application. There is a modern way to use this material disguised as structural pultruded element (with weight equal to 1600-1800 kg/m{sup 3}) in new constructions, local reinforcements and in other seismic applications. Actually the international technical and scientific literature in form of draft, recommendations andmore » researches on this topic is very rich also taking into account Italian contribution. Some interesting applications of all FRP structures in seismic engineering field are showed in this research in real terms and in form of capability.« less

Low Velocity Impact Behavior of Glass Filled Fiber-Reinforced Thermoplastic Engine Components

PubMed Central

Mouti, Zakaria; Westwood, Keith; Kayvantash, Kambiz; Njuguna, James

2010-01-01

This paper concerns automotive parts located underneath the engine and in particular the engine oil pan. Classically made of stamped steel or cast aluminum, new developments have allowed the manufacture oil pans with polyamide 66 reinforced by 35% weight of short glass fiber. However, polyamides have some limitations and the most significant is their response to localized impact loading. The nature of the impact considered here is of a typical stone collected from the road and projected into the oil pan.  Low velocity impact investigations were carried out using a gas gun and drop weight tower.  The study shows that the design of the oil pan has a significant contribution in the shock absorption. In addition to the material properties, the geometry and the ribbing both cleverly combined, increase the impact resistance of the component significantly. Areas of oil pan design improvement have been identified and conclusions drawn.

Research on the Application of GRC Material in Exhibition Decoration Engineering

NASA Astrophysics Data System (ADS)

Cai, Yan

2018-03-01

Glass fiber reinforced cement (GRC) is a kind of new building material which is based on cement and take the alkali resistant glass fiber as reinforcing material. It is mainly used in building decoration project and it has many advantages like environmental protection, economical, practical modeling and others. This paper mainly studies the concrete application of GRC material in exhibition building decoration project.

Ballistic impact velocity response of carbon fibre reinforced aluminium alloy laminates for aero-engine

NASA Astrophysics Data System (ADS)

Mohammed, I.; Abu Talib, A. R.; Sultan, M. T. H.; Saadon, S.

2017-12-01

Aerospace and other industries use fibre metal laminate composites extensively due to their high specific strength, stiffness and fire resistance, in addition to their capability to be tailored into different forms for specific purposes. The behaviours of such composites under impact loading is another factor to be considered due to the impacts that occur in take-off, landing, during maintenance and operations. The aim of the study is to determine the specific perforation energy and impact strength of the fibre metal laminates of different layering pattern of carbon fibre reinforced aluminium alloy and hybrid laminate composites of carbon fibre and natural fibres (kenaf and flax). The composites are fabricated using the hand lay-up method in a mould with high bonding polymer matrix and compressed by a compression machine, cured at room temperature for one day and post cure in an oven for three hours. The impact tests are conducted using a gun tunnel system with a flat cylindrical bullet fired using a helium gas at a distance of 14 inches to the target. Impact and residual velocity of the projectile are recorded by high speed video camera. Specific perforation energy of carbon fibre reinforced aluminium alloy (CF+AA) for both before and after fire test are higher than the specific perforation energy of the other composites considered before and after fire test respectively. CF +AA before fire test is 55.18% greater than after. The same thing applies to impact strength of the composites where CF +AA before the fire test has the highest percentage of 11.7%, 50.0% and 32.98% as respectively compared to carbon fibre reinforced aluminium alloy (CARALL), carbon fibre reinforced flax aluminium alloy (CAFRALL) and carbon fibre reinforced kenaf aluminium alloy (CAKRALL), and likewise for the composites after fire test. The considered composites in this test can be used in the designated fire zone of an aircraft engine to protect external debris from penetrating the engine shield due to higher values of impact strength and specific perforation energy as highlighted by the test results.

Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors

PubMed Central

Montanini, Roberto; Recupero, Antonino; De Domenico, Fabrizio; Freni, Fabrizio

2016-01-01

Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data. PMID:27669251

Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors.

PubMed

Montanini, Roberto; Recupero, Antonino; De Domenico, Fabrizio; Freni, Fabrizio

2016-09-22

Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data.

Cigarettes, social reinforcement, and culture: a commentary on "Tobacco as a social currency: cigarette gifting and sharing in China".

PubMed

Ding, Ding; Hovell, Melbourne F

2012-03-01

As Rich and Xiao suggested, cigarette sharing and gifting play an important role in China's smoking epidemic. Understanding the cultural roots, history, and impacts of such practices should be emphasized in tobacco control efforts. "Tobacco as a social currency" is a consequence of the tobacco industry usurping traditional values and cultural customs to make cigarette gifting acceptable, desirable, and socially reinforcing. The cigarettes-social reinforcement link created by the tobacco industry can be broken by deglamorizing smoking and cigarette gifting and by reinforcing alternative healthful behaviors. A behavioral ecological perspective, with an emphasis of understanding and engineering cultures, should guide future health promotion efforts to reduce smoking and other risk practices in China.

Questioning Power: Deframing the STEM Discourse

ERIC Educational Resources Information Center

Weinstein, Matthew; Blades, David; Gleason, Shannon C.

2016-01-01

Internationally, STEM has become a slogan for organizing new discourses and practices in science education. In the form of a three-act play, we argue that STEM as social engineering orients and organizes school science education curriculum development in directions of scientific innovation and engineering that reinforce and legitimize a neoliberal…

Geotextile reinforced bridge approach embankment : Lake River Bridge : Malin Highway , Klamath County, Oregon : construction report.

DOT National Transportation Integrated Search

1993-03-01

The transition from the roadway to the deck of a rigidly supported bridge is of concern to engineers and the travelling public. It is a common occurrence to feel a discontinuity between the roadway and bridge structure. Bridge engineers have tried to...

Fine modeling of reinforced thermoplastic filament winding container

NASA Astrophysics Data System (ADS)

Duan, Chenghong; Huang, Jinhao; Wu, Liang; Luo, Xiangpeng

2018-05-01

Reinforced thermoplastic containers has been widely used because of its corrosion-resistant, fatigue-resistant features. The characteristics of the liner and wound layer material and the different winding methods lead to the fact that the model obtained according to the ordinary pressure vessel modeling method does not reflect the actual situation of the reinforced thermoplastic container. In this paper, the thickness of stratified winding was calculated based on the principle of constant fiber total volume and equal cross-sectional area. ANSYS ACP module was used to refine the full winding container and provide a reference for engineering simulation solution.

The Effect of Different Shape and Perforated rHDPE in Concrete Structures on Flexural Strength

NASA Astrophysics Data System (ADS)

Yuhazri, MY; Hafiz, KM; Myia, YZA; Jia, CP; Sihombing, H.; Sapuan, SM; Badarulzaman, NA

2017-10-01

This research was carried out to develop a reinforcing structure from recycled HDPE plastic lubricant containers to be embedded in concrete structure. Different forms and shapes of recycled HDPE plastic are designed as reinforcement incorporate with cement. In this study, the reinforcing structure was prepared by washing, cutting, dimensioning and joining of the waste HDPE containers (direct technique without treatment on plastic surface). Then, the rHDPE reinforced concrete was produced by casting based on standard of procedure in civil engineering technique. Eight different shapes of rHDPE in concrete structure were used to determine the concrete’s ability in terms of flexural strength. Embedded round shape in solid and perforated of rHDPE in concrete system drastically improved flexural strength at 17.78 % and 13.79 %. The result would seem that the concrete with reinforcing rHDPE structure exhibits a more gradual or flexible properties than concrete beams without reinforcement that has the properties of fragile.

Engineering bioartificial tracheal tissue using hybrid fibroblast-mesenchymal stem cell cultures in collagen hydrogels.

PubMed

Naito, Hiroshi; Tojo, Takashi; Kimura, Michitaka; Dohi, Yoshiko; Zimmermann, Wolfram-Hubertus; Eschenhagen, Thomas; Taniguchi, Shigeki

2011-02-01

We aimed at providing the first in vitro and in vivo proof-of-concept for a novel tracheal tissue engineering technology. We hypothesized that bioartificial trachea (BT) could be generated from fibroblast and collagen hydrogels, mechanically supported by osteogenically-induced mesenchymal stem cells (MSC) in ring-shaped 3D-hydrogel cultures, and applied in an experimental model of rat trachea injury. Tube-shaped tissue was constructed from mixtures of rat fibroblasts and collagen in custom-made casting molds. The tissue was characterized histologically and mechanically. Ring-shaped tissue was constructed from mixtures of rat MSCs and collagen and fused to the tissue-engineered tubes to function as reinforcement. Stiffness of the biological reinforcement was enhanced by induction of osteogeneic differentiation in MSCs. Osteogenic differentiation was evaluated by assessment of osteocalcin (OC) secretion, quantification of calcium (Ca) deposit, and mechanical testing. Finally, BT was implanted to bridge a surgically-induced tracheal defect. A three-layer tubular tissue structure composed of an interconnected network of fibroblasts was constructed. Tissue collapse was prevented by the placement of MSC-containing ring-shaped tissue reinforcement around the tubular constructs. Osteogenic induction resulted in high OC secretion, high Ca deposit, and enhanced construct stiffness. Ultimately, when BT was implanted, recipient rats were able to breathe spontaneously.

Thermal and mechanical behaviour of sub micron sized fly ash reinforced polyester resin composite

NASA Astrophysics Data System (ADS)

Nantha Kumar, P.; Rajadurai, A.; Muthuramalingam, T.

2018-04-01

The utilization of particles reinforced resin matrix composites is being increased owing to its lower density and high strength to weight ratio. In the present study, an attempt has been made to synthesize fly ash particles reinforced polyester resin composite for engine cowling application. The thermal stability and mechanical behaviours such as hardness and flexural strength of the composite with 2, 3 and 4 weight % of reinforcement is studied and analyzed. The thermo gravimetric analysis indicates that the higher addition of reinforcement increases the decomposition temperature due to its refractory nature. It is also observed that the hardness increases with higher filler addition owing to the resistance of FA particles towards penetration. The flexural strength is found to increase up to the addition of 3% of FA particles, whereas the polyester resin composite prepared with 4% FA particles addition is observed to have low flexural strength owing to agglomeration of particles.

Study of the internal confinement of concrete reinforced (in civil engineering) with woven reinforcement

NASA Astrophysics Data System (ADS)

Dalal, M.; Goumairi, O.; El Malik, A.

2017-10-01

Concrete is generally the most used material in the field of construction. Despite its extensive use in structures, it represents some drawbacks related to its properties including its low tensile strength and low ductility. To solve this problem, the use of steel reinforcement in concrete structures is possible. Another possibility is the introduction of different types of continuous fibre / staple in the concrete, such as steel fibres or synthetic fibres, to obtain ″Concretes bundles″. Many types of fibre concrete, which have been developed and for many of them, the gain provided by the fibre was rather low and no significant improvement in tensile strength was really reaching. By cons, the ductility was higher than that of ordinary concrete. The objective of this study is to examine concrete reinforcement by inserting reinforcements woven polyester. These are either woven bidirectional (2D) or three-dimensional woven (3D). So we will report the properties of each type of reinforcement and the influence of the method of weaving on the strength reinforcements and on the strength of concrete in which they are incorporated. Such influence should contribute to improving the sustainability and enhancement of reinforcement

Large strain variable stiffness composites for shear deformations with applications to morphing aircraft skins

NASA Astrophysics Data System (ADS)

McKnight, G. P.; Henry, C. P.

2008-03-01

Morphing or reconfigurable structures potentially allow for previously unattainable vehicle performance by permitting several optimized structures to be achieved using a single platform. The key to enabling this technology in applications such as aircraft wings, nozzles, and control surfaces, are new engineered materials which can achieve the necessary deformations but limit losses in parasitic actuation mass and structural efficiency (stiffness/weight). These materials should exhibit precise control of deformation properties and provide high stiffness when exercised through large deformations. In this work, we build upon previous efforts in segmented reinforcement variable stiffness composites employing shape memory polymers to create prototype hybrid composite materials that combine the benefits of cellular materials with those of discontinuous reinforcement composites. These composites help overcome two key challenges for shearing wing skins: the resistance to out of plane buckling from actuation induced shear deformation, and resistance to membrane deflections resulting from distributed aerodynamic pressure loading. We designed, fabricated, and tested composite materials intended for shear deformation and address out of plane deflections in variable area wing skins. Our designs are based on the kinematic engineering of reinforcement platelets such that desired microstructural kinematics is achieved through prescribed boundary conditions. We achieve this kinematic control by etching sheets of metallic reinforcement into regular patterns of platelets and connecting ligaments. This kinematic engineering allows optimization of materials properties for a known deformation pathway. We use mechanical analysis and full field photogrammetry to relate local scale kinematics and strains to global deformations for both axial tension loading and shear loading with a pinned-diamond type fixture. The Poisson ratio of the kinematically engineered composite is ~3x higher than prototypical orthotropic variable stiffness composites. This design allows us to create composite materials that have high stiffness in the cold state below SMP T g (4-14GPa) and yet achieve large composite shear strains (5-20%) in the hot state (above SMP T g).

Ceramic composites for rocket engine turbines

NASA Technical Reports Server (NTRS)

Herbell, Thomas P.; Eckel, Andrew J.

1991-01-01

The use of ceramic materials in the hot section of the fuel turbopump of advanced reusable rocket engines promises increased performance and payload capability, improved component life and economics, and greater design flexibility. Severe thermal transients present during operation of the Space Shuttle Main Engine (SSME), push metallic components to the limit of their capabilities. Future engine requirements might be even more severe. In phase one of this two-phase program, performance benefits were quantified and continuous fiber reinforced ceramic matrix composite components demonstrated a potential to survive the hostile environment of an advanced rocket engine turbopump.

Ceramic composites for rocket engine turbines

NASA Technical Reports Server (NTRS)

Herbell, Thomas P.; Eckel, Andrew J.

1991-01-01

The use of ceramic materials in the hot section of the fuel turbopump of advanced reusable rocket engines promises increased performance and payload capability, improved component life and economics, and greater design flexibility. Severe thermal transients present during operation of the Space Shuttle Main Engine (SSME), push metallic components to the limit of their capabilities. Future engine requirements might be even more severe. In phase one of this two-phase program, performance benefits were quantified and continuous fiber reinforced ceramic matrix composite components demonstrated a potential to survive the hostile environment of an advaced rocket engine turbopump.

3D Bioprinting of Developmentally Inspired Templates for Whole Bone Organ Engineering.

PubMed

Daly, Andrew C; Cunniffe, Gráinne M; Sathy, Binulal N; Jeon, Oju; Alsberg, Eben; Kelly, Daniel J

2016-09-01

The ability to print defined patterns of cells and extracellular-matrix components in three dimensions has enabled the engineering of simple biological tissues; however, bioprinting functional solid organs is beyond the capabilities of current biofabrication technologies. An alternative approach would be to bioprint the developmental precursor to an adult organ, using this engineered rudiment as a template for subsequent organogenesis in vivo. This study demonstrates that developmentally inspired hypertrophic cartilage templates can be engineered in vitro using stem cells within a supporting gamma-irradiated alginate bioink incorporating Arg-Gly-Asp adhesion peptides. Furthermore, these soft tissue templates can be reinforced with a network of printed polycaprolactone fibers, resulting in a ≈350 fold increase in construct compressive modulus providing the necessary stiffness to implant such immature cartilaginous rudiments into load bearing locations. As a proof-of-principal, multiple-tool biofabrication is used to engineer a mechanically reinforced cartilaginous template mimicking the geometry of a vertebral body, which in vivo supported the development of a vascularized bone organ containing trabecular-like endochondral bone with a supporting marrow structure. Such developmental engineering approaches could be applied to the biofabrication of other solid organs by bioprinting precursors that have the capacity to mature into their adult counterparts over time in vivo. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Friction and wear performance of some thermoplastic polymers and polymer composites against unsaturated polyester

NASA Astrophysics Data System (ADS)

Unal, H.; Mimaroglu, A.; Arda, T.

2006-09-01

Wear experiments have been carried out with a range of unfilled and filled engineering thermoplastic polymers sliding against a 15% glass fibre reinforced unsaturated polyester polymer under 20, 40 and 60 N loads and 0.5 m/s sliding speed. Pin materials used in this experimental investigation are polyamide 66 (PA 66), poly-ether-ether-ketone (PEEK) and aliphatic polyketone (APK), glass fibre reinforced polyamide 46 (PA 46 + 30% GFR), glass fibre reinforced polytetrafluoroethylene (PTFE + 17% GFR), glass fibre reinforced poly-ether-ether-ketone (PEEK + 20% GFR), glass fibre reinforced poly-phylene-sulfide (PPS + 30% GFR), polytetrafluoroethylene filled polyamide 66 (PA 66 + 10% PTFE) and bronze filled pofytetrafluoroethylene (PTFE + 25% bronze) engineering polymers. The disc material is a 15% glass fibre reinforced unsaturated polyester thermoset polymer produced by Bulk Moulding Compound (BMC). Sliding wear tests were carried out on a pin-on-disc apparatus under 0.5 m/s sliding speed and load values of 20, 40 and 60 N. The results showed that the highest specific wear rate is for PPS + 30% GFR with a value of 1 × 10 -11 m 2/N and the lowest wear rate is for PTFE + 17% GFR with a value of 9.41 × 10 -15 m 2/N. For the materials and test conditions of this investigation, apart from polyamide 66 and PA 46 + 30% GFR polymers, the coefficient of friction and specific wear rates are not significantly affected by the change in load value. For polyamide 66 and PA 46 + 30% GFR polymers the coefficient of friction and specific wear rates vary linearly with the variation in load values.

Erosion Control at TRESTLE. An Engineering Study, CE 551.

DTIC Science & Technology

1984-05-01

Stabilenka is a polyester fabric. This polymer T40 was specifically selected because its inherent fiber properties make it highly conducive to 50...of prewet ~water be varied up to approximately 0.1 gal. per so. yd. The prewet water should be applied before the fiber glass reinforcing in one...the second application) with the fiber glass reinforcing placed between applications. All these test sections should be photographed monthly to

Corrosion/Degradation Monitoring Technology for Composite Materials used to Extend Building Service Life

DTIC Science & Technology

2014-07-01

for patching concrete structures that have corroded reinforcing steel , but the Army largely avoids structural composite repair applications because...J. Dunmire (OUSD(AT&L)), Bernie Rodriguez (IMPW-FM), and Valerie D. Hines (DAIM-ODF). The work was performed by the Engineering and Materials...buildings in the Army inventory often have se- verely corroded reinforcing steel that necessitates structural upgrades for conformance to current safety

Compressive Membrane Capability Estimates in Laterally Edge Restrained Reinforced Concrete One-Way Slabs

DTIC Science & Technology

1999-05-01

by THE UNITED STATES ARMY, I DEPARTMENT OF CIVIL AND MECHANICAL ENGINEERINGI UNITED STATES MILITARY ACADEMY and DEPARTMENT OF CIVIL AND ENVIRONMENTAL ...SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING I MONITORING AG-ENCY REPORT NUMBER Department of Civil and Environmental ...LATERALLY EDGE RESTRAINED REINFORCED CONCRETE ONE-WAY SLABS Ronald Wayne Welch, Ph.D. Department of Civil and Environmental Engineering University of

Predictive Models for Dynamic Brittle Fracture and Damage at High-velocity Impact in Multilayered Targets

DTIC Science & Technology

2016-11-01

layered glass/PC systems,Functionally Graded Materials (FGMs), polycrystalline AlON, and fiber-reinforced composite (FRC) materials. For the first time we...multi-layered glass/PC systems,Functionally Graded Materials (FGMs), polycrystalline AlON, and fiber-reinforced composite (FRC) materials. For the... Composite Lamina with Peridynamics, International Journal for Multiscale Computational Engineering, (12 2011): 0. doi: Florin Bobaru, Youn Doh Ha

Tuning Material and Component Properties to Reduce Weight and Increase Blastworthiness of a Notional V-Hull Structure

DTIC Science & Technology

2015-04-24

for designing blast-resistant structures [16]. The failure mechanisms in unidirectional fiber -reinforced composites of delamination, fiber -matrix...Batra, R.C., and Hassan, N.M., “Blast resistance of unidirectional fiber reinforced composites ,” Composites Part B: Engineering, 2008 18. Liu, X...feature a lighter weight structure, because this enables faster transport, higher mobility, greater fuel conservation, higher payload capacity, and

Reinforced nanohydroxyapatite/polyamide66 scaffolds by chitosan coating for bone tissue engineering.

PubMed

Huang, Di; Zuo, Yi; Zou, Qin; Wang, Yanying; Gao, Shibo; Wang, Xiaoyan; Liu, Haohuai; Li, Yubao

2012-01-01

High porosity of scaffold is always accompanied by poor mechanical property; the aim of this study was to enhance the strength and modulus of the highly porous scaffold of nanohydroxyapatite/polyamide66 (n-HA/PA66) by coating chitosan (CS) and to investigate the effect of CS content on the scaffold physical properties and cytological properties. The results show that CS coating can reinforce the scaffold effectively. The compress modulus and strength of the CS coated n-HA/PA66 scaffolds are improved to 32.71 and 2.38 MPa, respectively, being about six times and five times of those of the uncoated scaffolds. Meanwhile, the scaffolds still exhibit a highly interconnected porous structure and the porosity is approximate about 78%, slightly lower than the value (84%) of uncoated scaffold. The cytological properties of scaffolds were also studied in vitro by cocultured with osteoblast-like MG63 cells. The cytological experiments demonstrate that the reinforced scaffolds display favorable cytocompatibility and have no significant difference with the uncoated n-HA/PA66 scaffolds. The CS reinforced n-HA/PA66 scaffolds can meet the basic mechanical requirement of bone tissue engineering scaffold, presenting a potential for biomedical application in bone reconstruction and repair. Copyright © 2011 Wiley Periodicals, Inc.

The Secrets to Increasing Females in Technology

ERIC Educational Resources Information Center

Shanahan, Betty

2006-01-01

The assumption that technology and engineering is for boys is reinforced by the reality of the severe under-representation of women as both practitioners and teachers of engineering and technology. The secret to increasing the number of females in technology is not to "fix" the girls but to make the technology classroom and profession more…

A comprehensive study on the fabrication and properties of biocomposites of poly(lactic acid)/ceramics for bone tissue engineering.

PubMed

Tajbakhsh, Saeid; Hajiali, Faezeh

2017-01-01

The fabrication of a suitable scaffold material is one of the major challenges for bone tissue engineering. Poly(lactic acid) (PLA) is one of the most favorable matrix materials in bone tissue engineering owing to its biocompatibility and biodegradability. However, PLA suffers from some shortcomings including low degradation rate, low cell adhesion caused by its hydrophobic property, and inflammatory reactions in vivo due to its degradation product, lactic acid. Therefore, the incorporation of bioactive reinforcements is considered as a powerful method to improve the properties of PLA. This review presents a comprehensive study on recent advances in the synthesis of PLA-based biocomposites containing ceramic reinforcements, including various methods of production and the evaluation of the scaffolds in terms of porosity, mechanical properties, in vitro and in vivo biocompatibility and bioactivity for bone tissue engineering applications. The production routes range from traditional approaches such as the use of porogens to provide porosity in the scaffolds to novel methods such as solid free-form techniques. Copyright © 2016 Elsevier B.V. All rights reserved.

Laser-assisted nanoceramics reinforced polymer scaffolds for tissue engineering: additional heating and stem cells behavior

NASA Astrophysics Data System (ADS)

Shishkovsky, Igor; Scherbakov, Vladimir; Volchkov, Vladislav; Volova, Larisa

2018-02-01

The conditions of selective laser melting (SLM) of tissue engineering scaffolds affect cell response and must be engineered to support cell adhesion, proliferation, and differentiation. In the present study, the influence of additional heating during SLM process on stem cell viability near biopolymer matrix reinforced by nanoceramics additives was carried out. We used the biocompatible and bioresorbable polymers (polyetheretherketone /PEEK/ and polycaprolactone /PCL/) as a matrix and nano-oxide ceramics - TiO2, Al2O3, ZrO2, FexOy and/or hydroxyapatite as a basis of the additives. The rate of pure PEEK and PCL bio-resorption and in mixtures with nano oxides on the matrix was studied by the method of mass loss on bacteria of hydroxylase and enzyme complex. The stem cellular morphology, proliferative MMSC activity, and adhesion of the 2D and 3D nanocomposite matrices were the subjects of comparison. Medical potential of the SLS/M-fabricated nano-oxide ceramics after additional heating as the basis for tissue engineering scaffolds and cell targeting systems were discussed.

Characterization of Thermal Behavior of Epoxy Composites Reinforced with Curaua Fibers by Differential Scanning Calorimetry

NASA Astrophysics Data System (ADS)

Barcelos, Mariana A.; Ribeiro, Carolina Gomes D.; Ferreira, Jordana; Vieira, Janaina da S.; Margem, Frederico M.; Monteiro, Sergio N.

Epoxy composites reinforced with natural lignocellulosic fibers have, in recent times, been gaining attention in engineering areas as lighter and cheaper alternatives for traditional composites such as the "fiberglass". The curaua fiber is the one strongest today being considered as reinforcement of composites for automobile interior parts. In fact, several studies are currently being dedicated to curaua fiber composites since physical and mechanical properties are required for practical uses. In this work, the thermal behavior of epoxy composites reinforced with up to 30 % in volume of curaua fibers was investigated by differential scanning calorimetry, DSC. The results showed endothermic and exothermic events associated with water release and possible molecular chain amorphous transformation. Comparison with similar composites permitted to propose mechanism that explains this DSC thermal behavior.

Carbon Fiber Reinforced Ceramic Composites for Propulsion Applications

NASA Technical Reports Server (NTRS)

Freedman, Marc (Technical Monitor); Shivakumar, Kunigal N.

2003-01-01

Fiber reinforced ceramic composites are materials of choice for gas turbine engines because of their high thermal efficiency, thrust/weight ratio, and operating temperatures. However, the successful introduction of ceramic composites to hot structures is limited because of excessive cost of manufacturing, reproducibility, nonuniformity, and reliability. Intense research is going on around the world to address some of these issues. The proposed effort is to develop a comprehensive status report of the technology on processing, testing, failure mechanics, and environmental durability of carbon fiber reinforced ceramic composites through extensive literature study, vendor and end-user survey, visits to facilities doing this type of work, and interviews. Then develop a cooperative research plan between NASA GRC and NCA&T (Center for Composite Materials Research) for processing, testing, environmental protection, and evaluation of fiber reinforced ceramic composites.

Geopolymer concrete for structural use: Recent findings and limitations

NASA Astrophysics Data System (ADS)

Nuruddin, M. F.; Malkawi, A. B.; Fauzi, A.; Mohammed, B. S.; Almattarneh, H. M.

2016-06-01

Geopolymer binders offer a possible solution for several problems that facing the current cement industry. These binders exhibit similar or better engineering properties compared to cement and can utilize several types of waste materials. This paper presents the recent research progress regarding the structural behaviour of reinforced geopolymer concrete members including beams, columns and slabs. The reported results showed that the structural behaviour of the reinforced geopolymer concrete members is similar to the known behaviour of the ordinary reinforced concrete members. In addition, the currently available standards have been conservatively used for analysis and designing of reinforced geopolymer concrete structures. On the other hand, the main hurdles facing the spread of geopolymer concrete was the absence of standards and the concerns about the long-term properties. Other issues included the safety, cost and liability.

Seismic Behavior and Retrofit of Concrete Columns of Old R.C. Buildings Reinforced With Plain Bars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marefat, M. S.; Arani, K. Karbasi; Shirazi, S. M. Hassanzadeh

2008-07-08

Seismic rehabilitation of old buildings has been a major challenge in recent years. The first step in seismic rehabilitation is evaluation of the existing capacity and the seismic behaviour. For investigation of the seismic behaviour of RC members of a real old building in Iran which has been designed and constructed by European engineers in 1940, three half-scale column specimens reinforced with plain bars have been tested. The tests indicate significant differences between the responses of specimens reinforced by plain bars relative to those reinforced by deformed bars. A regular pattern of cracking and a relatively brittle behaviour was observedmore » while a relatively large residual strength appeared after sudden drop of initial strength and stiffness due to slip of longitudinal bars.« less

Experimental Study on Vacuum Dynamic Consolidation Treatment of Soft Soil Foundation

NASA Astrophysics Data System (ADS)

Fu-lai, Ni; Xin, Wen; Xiao-bin, Zhang; Wei, Li

2017-11-01

In view of the deficiency of the saturated silt clay foundation reinforced by the dynamic consolidation method, combination the project of soft foundation treatment test area in Tangshan, the reaserch analysed indexes, included groundwater level, pore water pressure, settlement about soil layer and so on, by use of field tests and indoor geotechnical tests, The results showed that the whole reinforcement effect with vacuum dynamic compaction method to blow fill foundation is obvious, due to the result of vacuum precipitation, generally, the excess pore water pressure can be dissipated by 90% above in 2 days around and the effective compaction coefficient can reached more than 0.9,the research work in soft foundation treatment engineering provide a new method and thought to similar engineering.

Nondestructive evaluation of concrete structures by nonstationary thermal wave imaging

NASA Astrophysics Data System (ADS)

Mulaveesala, Ravibabu; Panda, Soma Sekhara Balaji; Mude, Rupla Naik; Amarnath, Muniyappa

2012-06-01

Reinforced concrete structures (RCS) have potential application in civil engineering and with the advent of nuclear engineering RCS to be capable enough to withstanding a variety of adverse environmental conditions. However, failures/loss of durability of designed structures due to premature reinforcement corrosion of rebar is a major constrain. Growing concern of safety of structure due to pre-mature deterioration has led to a great demand for development of non-destructive and non-contact testing techniques for monitoring and assessing health of RCS. This paper presents an experimental investigation of rebar corrosion by non-stationary thermal wave imaging. Experimental results have been proven, proposed approach is an effective technique for identification of corrosion in rebar in the concrete samples.

Mechanical-physical experimental tests on lime mortars and bricks reinforced with hemp

NASA Astrophysics Data System (ADS)

Formisano, Antonio; Dessı, Enzo; Landolfo, Raffaele

2017-11-01

Hemp is an agricultural product used for various applications. In the Civil Engineering field, only a limited use of this natural material, called the "green pig" since exploitation of all its constituent parts is allowed, has been done. For this reason, in the paper an experimental activity on lime mortars and bricks reinforced with hemp components has been performed. Compression and bending tests have been carried out on specimens manufactured with hemp shives and fibres, respectively. The achieved results have shown that hemp products change the failure modes from brittle to ductile, leaving basically unaltered the strength capacity of reinforced specimens with respect to unreinforced ones.

Towards Large-Scale, Non-Destructive Inspection of Concrete Bridges

NASA Astrophysics Data System (ADS)

Mahmoud, A.; Shah, A. H.; Popplewell, N.

2005-04-01

It is estimated that the rehabilitation of deteriorating engineering infrastructure in the harsh North American environment could cost billions of dollars. Bridges are key infrastructure components for surface transportation. Steel-free and fibre-reinforced concrete is used increasingly nowadays to circumvent the vulnerability of steel rebar to corrosion. Existing steel-free and fibre-reinforced bridges may experience extensive surface-breaking cracks that need to be characterized without incurring further damage. In the present study, a method that uses Lamb elastic wave propagation to non-destructively characterize cracks in plain as well as fibre-reinforced concrete is investigated both numerically and experimentally. Numerical and experimental data are corroborated with good agreement.

Experimental Investigation of Fibre Reinforced Composite Materials Under Impact Load

NASA Astrophysics Data System (ADS)

Koppula, Sravani; Kaviti, Ajay kumar; Namala, Kiran kumar

2018-03-01

Composite materials are extensively used in various engineering applications. They have very high flexibility design which allows prescribe tailoring of material properties by lamination of composite fibres with reinforcement of resin to it. Complex failure condition prevail in the composite materials under the action of impact loads, major modes of failure in composite may include matrix cracking, fibre matrix, fibre breakage, de-bonding or de- lamination between composite plies. This paper describes the mechanical properties of glass fibre reinforced composite material under impact loading conditions through experimental setup. Experimental tests are performed according to ASTM standards using impact testing machines like Charpy test, computerized universal testing machine.

Evidence-based practice implementation in community mental health settings: the relative importance of key domains of implementation activity.

PubMed

Torrey, William C; Bond, Gary R; McHugo, Gregory J; Swain, Karin

2012-09-01

Implementation research has examined practice prioritization, implementation leadership, workforce development, workflow re-engineering, and practice reinforcement, but not addressed their relative importance as implementation drivers. This study investigated domains of implementation activities and correlated them to implementation success during a large national evidence-based practice implementation project. Implementation success was correlated with active leadership strategically devoted to redesigning the flow of work and reinforcing implementation through measurement and feedback. Relative attention to workforce development was negatively correlated with implementation. Active leaders should focus on redesigning the flow of work to support the implementation and on reinforcing program improvements.

Functionally Graded Shape Memory Alloy Composites Optimized for Passive Vibration Control

DTIC Science & Technology

2006-11-20

Nitinol , it is anticipated that the wire can only experience an incomplete hysteresis. 2.1. SMA wires in sleeves continuously bonded to the plate...Gilheany, J. 1995. Control of the natural frequencies of nitinol -reinforced composite beams, Journal of Sound and Vibrations, Vol. 185, 171-185. 3 Ro...J., and Baz, A., 1995. Nitinol -reinforced plates: Part III, Dynamic characteristics, Composites Engineering, Vol. 5, 91-106. 4 Epps, J and Chandra

Computational Analysis of Effect of Transient Fluid Force on Composite Structures

DTIC Science & Technology

2013-12-01

as they well represent an E-glass fiber reinforced composite frequently used in research and industrial applications. The fluid domain was sized...provide unique perspectives on peak stress ratios . The two models both share increased structural rigidity. The cylinder is reinforced by... Poisson ratio of 0.3 and Young’s modulus of 20 GPa were added to the transient structural engineering data cell (Figure 69). 78 Figure 69. E-Glass

16. 'Concrete Bridge Over Salt River, Port Kenyon, Humboldt County, ...

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

16. 'Concrete Bridge Over Salt River, Port Kenyon, Humboldt County, California, A.J. Logan, County Surveyor, H.J. Brunnier, Consulting Engineer, March 7, 1919,' showing detail of floor beam at central pier, half section of cantilever slab at end of bridge, floor beam end panels, slab reinforcing, plan of slab reinforcing, diagram of slab bars, typical floor girder. - Salt River Bridge, Spanning Salt River at Dillon Road, Ferndale, Humboldt County, CA

A Brief Research Review for Improvement Methods the Wettability between Ceramic Reinforcement Particulate and Aluminium Matrix Composites

NASA Astrophysics Data System (ADS)

Razzaq, Alaa Mohammed; Majid, Dayang Laila Abang Abdul; Ishak, M. R.; B, Uday M.

2017-05-01

The development of new methods for addition fine ceramic powders to Al aluminium alloy melts, which would lead to more uniform distribution and effective incorporation of the reinforcement particles into the aluminium matrix alloy. Recently the materials engineering research has moved to composite materials from monolithic, adapting to the global need for lightweight, low cost, quality, and high performance advanced materials. Among the different methods, stir casting is one of the simplest ways of making aluminium matrix composites. However, it suffers from poor distribution and combination of the reinforcement ceramic particles in the metal matrix. These problems become significantly effect to reduce reinforcement size, more agglomeration and tendency with less wettability for the ceramic particles in the melt process. Many researchers have carried out different studies on the wettability between the metal matrix and dispersion phase, which includes added wettability agents, fluxes, preheating the reinforcement particles, coating the reinforcement particles, and use composting techniques. The enhancement of wettability of ceramic particles by the molten matrix alloy and the reinforcement particles distribution improvement in the solidified matrix is the main objective for many studies that will be discussed in this paper.

Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

PubMed Central

Wang, Z.; Georgarakis, K.; Nakayama, K. S.; Li, Y.; Tsarkov, A. A.; Xie, G.; Dudina, D.; Louzguine-Luzgin, D. V.; Yavari, A. R.

2016-01-01

Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses. PMID:27067824

A State-of-the-Art Review on Soil Reinforcement Technology Using Natural Plant Fiber Materials: Past Findings, Present Trends and Future Directions.

PubMed

Gowthaman, Sivakumar; Nakashima, Kazunori; Kawasaki, Satoru

2018-04-04

Incorporating sustainable materials into geotechnical applications increases day by day due to the consideration of impacts on healthy geo-environment and future generations. The environmental issues associated with conventional synthetic materials such as cement, plastic-composites, steel and ashes necessitate alternative approaches in geotechnical engineering. Recently, natural fiber materials in place of synthetic material have gained momentum as an emulating soil-reinforcement technique in sustainable geotechnics. However, the natural fibers are innately different from such synthetic material whereas behavior of fiber-reinforced soil is influenced not only by physical-mechanical properties but also by biochemical properties. In the present review, the applicability of natural plant fibers as oriented distributed fiber-reinforced soil (ODFS) and randomly distributed fiber-reinforced soil (RDFS) are extensively discussed and emphasized the inspiration of RDFS based on the emerging trend. Review also attempts to explore the importance of biochemical composition of natural-fibers on the performance in subsoil reinforced conditions. The treatment methods which enhances the behavior and lifetime of fibers, are also presented. While outlining the current potential of fiber reinforcement technology, some key research gaps have been highlighted at their importance. Finally, the review briefly documents the future direction of the fiber reinforcement technology by associating bio-mediated technological line.

A State-of-the-Art Review on Soil Reinforcement Technology Using Natural Plant Fiber Materials: Past Findings, Present Trends and Future Directions

PubMed Central

Gowthaman, Sivakumar; Nakashima, Kazunori; Kawasaki, Satoru

2018-01-01

Incorporating sustainable materials into geotechnical applications increases day by day due to the consideration of impacts on healthy geo-environment and future generations. The environmental issues associated with conventional synthetic materials such as cement, plastic-composites, steel and ashes necessitate alternative approaches in geotechnical engineering. Recently, natural fiber materials in place of synthetic material have gained momentum as an emulating soil-reinforcement technique in sustainable geotechnics. However, the natural fibers are innately different from such synthetic material whereas behavior of fiber-reinforced soil is influenced not only by physical-mechanical properties but also by biochemical properties. In the present review, the applicability of natural plant fibers as oriented distributed fiber-reinforced soil (ODFS) and randomly distributed fiber-reinforced soil (RDFS) are extensively discussed and emphasized the inspiration of RDFS based on the emerging trend. Review also attempts to explore the importance of biochemical composition of natural-fibers on the performance in subsoil reinforced conditions. The treatment methods which enhances the behavior and lifetime of fibers, are also presented. While outlining the current potential of fiber reinforcement technology, some key research gaps have been highlighted at their importance. Finally, the review briefly documents the future direction of the fiber reinforcement technology by associating bio-mediated technological line. PMID:29617285

Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application. Phase 1 summary report: Shear web design development

NASA Technical Reports Server (NTRS)

Laakso, J. H.; Zimmerman, D. K.

1972-01-01

An advanced composite shear web design concept was developed for the Space Shuttle orbiter main engine thrust beam structure. Various web concepts were synthesized by a computer-aided adaptive random search procedure. A practical concept is identified having a titanium-clad + or - 45 deg boron/epoxy web plate with vertical boron/epoxy reinforced aluminum stiffeners. The boron-epoxy laminate contributes to the strength and stiffness efficiency of the basic web section. The titanium-cladding functions to protect the polymeric laminate parts from damaging environments and is chem-milled to provide reinforcement in selected areas. Detailed design drawings are presented for both boron/epoxy reinforced and all-metal shear webs. The weight saving offered is 24% relative to all-metal construction at an attractive cost per pound of weight saved, based on the detailed designs. Small scale element tests substantiate the boron/epoxy reinforced design details in critical areas. The results show that the titanium-cladding reliably reinforces the web laminate in critical edge load transfer and stiffener fastener hole areas.

Structural Behavior of Concrete Beams Reinforced with Basalt Fiber Reinforced Polymer (BFRP) Bars

NASA Astrophysics Data System (ADS)

Ovitigala, Thilan

The main challenge for civil engineers is to provide sustainable, environmentally friendly and financially feasible structures to the society. Finding new materials such as fiber reinforced polymer (FRP) material that can fulfill the above requirements is a must. FRP material was expensive and it was limited to niche markets such as space shuttles and air industry in the 1960s. Over the time, it became cheaper and spread to other industries such as sporting goods in the 1980-1990, and then towards the infrastructure industry. Design and construction guidelines are available for carbon fiber reinforced polymer (CFRP), aramid fiber reinforced polymer (AFRP) and glass fiber reinforced polymer (GFRP) and they are currently used in structural applications. Since FRP is linear elastic brittle material, design guidelines for the steel reinforcement are not valid for FRP materials. Corrosion of steel reinforcement affects the durability of the concrete structures. FRP reinforcement is identified as an alternative to steel reinforcement in corrosive environments. Although basalt fiber reinforced polymer (BFRP) has many advantages over other FRP materials, but limited studies have been done. These studies didn't include larger BFRP bar diameters that are mostly used in practice. Therefore, larger beam sizes with larger BFRP reinforcement bar diameters are needed to investigate the flexural and shear behavior of BFRP reinforced concrete beams. Also, shear behavior of BFRP reinforced concrete beams was not yet studied. Experimental testing of mechanical properties and bond strength of BFRP bars and flexural and shear behavior of BFRP reinforced concrete beams are needed to include BFRP reinforcement bars in the design codes. This study mainly focuses on the use of BFRP bars as internal reinforcement. The test results of the mechanical properties of BFRP reinforcement bars, the bond strength of BFRP reinforcement bars, and the flexural and shear behavior of concrete beams reinforced with BFRP reinforcement bars are presented and verified with other research studies, existing design codes and guidelines provided for other FRP bars. Based on the experimental testing results, analytical equations were developed and existing equations were modified to predict the actual structural behavior of FRP bar reinforced concrete beams with reasonable accuracy.

An Analysis of Insulated Concrete Forms for use in Sustainable Military Construction

DTIC Science & Technology

2014-03-27

CONSTRUCTION THESIS Presented to the Faculty Department of Systems and Engineering Management Graduate School of Engineering and Management...which fit together and are filled with reinforced concrete to construct the exterior wall systems of a building. By design, this material provides a...Forms with Rebar .............................................................. 12 Figure 3. Cut outs of ICF wall systems

Mechanical characterization of glass fiber (woven roving/chopped strand mat E-glass fiber) reinforced polyester composites

NASA Astrophysics Data System (ADS)

Bhaskar, V. Vijaya; Srinivas, Kolla

2017-07-01

Polymer reinforced composites have been replacing most of the engineering material and their applications become more and more day by day. Polymer composites have been analyzing from past thirty five years for their betterment for adapting more applications. This paper aims at the mechanical properties of polyester reinforced with glass fiber composites. The glass fiber is reinforced with polyester in two forms viz Woven Rovings (WRG) and Chopped Strand Mat (CSMG) E-glass fibers. The composites are fabricated by hand lay-up technique and the composites are cut as per ASTM Standard sizes for corresponding tests like flexural, compression and impact tests, so that flexural strength, compression strength, impact strength and inter laminar shear stress(ILSS) of polymer matrix composites are analyzed. From the tests and further calculations, the polyester composites reinforced with Chopped Strand Mat glass fiber have shown better performance against flexural load, compression load and impact load than that of Woven Roving glass fiber.

Calculation of load-bearing capacity of prestressed reinforced concrete trusses by the finite element method

NASA Astrophysics Data System (ADS)

Agapov, Vladimir; Golovanov, Roman; Aidemirov, Kurban

2017-10-01

The technique of calculation of prestressed reinforced concrete trusses with taking into account geometrical and physical nonlinearity is considered. As a tool for solving the problem, the finite element method has been chosen. Basic design equations and methods for their solution are given. It is assumed that there are both a prestressed and nonprestressed reinforcement in the bars of the trusses. The prestress is modeled by setting the temperature effect on the reinforcement. The ways of taking into account the physical and geometrical nonlinearity for bars of reinforced concrete trusses are considered. An example of the analysis of a flat truss is given and the behavior of the truss on various stages of its loading up to destruction is analyzed. A program for the analysis of flat and spatial concrete trusses taking into account the nonlinear deformation is developed. The program is adapted to the computational complex PRINS. As a part of this complex it is available to a wide range of engineering, scientific and technical workers

Combined effect of high curing temperature and crack width on chloride migration in reinforced concrete beams

NASA Astrophysics Data System (ADS)

Elkedrouci, L.; Diao, B.; Pang, S.; Li, Y.

2018-03-01

Deterioration of reinforced concrete structures is a serious concern in the construction engineering, largely due to chloride induced corrosion of reinforcement. Chloride penetration is markedly influenced by one or several major factors at the same time such as cuing in combination with different crack widths which have spectacular effect on reinforced concrete structures. This research presents the results of an experimental investigation involving reinforced concrete beams with three different crack widths ranging from 0 to 0.2mm, curing temperatures of 20°C or 40°C and water-to-cement of 0.5. Chloride content profiles were determined under non-steady state diffusion at 20°C. Based on the obtained results, higher chloride content was obtained under condition of high curing temperature in combination with large crack more than 0.1mm and there are no significant differences between narrow crack width (less than 0.1 mm) and beams without crack (0 mm).

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, the media record workers on the job preparing the orbiter Atlantis for Return to Flight. Both local and national reporters representing print and TV networks were invited to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

NASA Image and Video Library

2003-09-26

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, the media record workers on the job preparing the orbiter Atlantis for Return to Flight. Both local and national reporters representing print and TV networks were invited to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

Permanent Seismically Induced Displacement of Rock-Founded Structures Computed by the Newmark Program

DTIC Science & Technology

2009-02-01

solved, great care is exercised by the seismic engineer to size the mesh so that moderate to high wave frequencies are not artificially excluded in...buttressing effect of a reinforced concrete slab (Figure 1.7) is represented in this simplified dynamic model by the user-specified force Presist...retaining wall that is buttressed by an invert spill- way slab (which is a reinforced concrete slab), exemplify a category of Corps retaining walls that may

Differentiation of osteoclast precursors on gellan gum-based spongy-like hydrogels for bone tissue engineering.

PubMed

Maia, F Raquel; Musson, David S; Naot, Dorit; da Silva, Lucilia P; Bastos, Ana R; Costa, João B; Oliveira, Joaquim M; Correlo, Vitor M; Reis, Rui L; Cornish, Jillian

2018-03-16

Bone tissue engineering with cell-scaffold constructs has been attracting a lot of attention, in particular as a tool for the efficient guiding of new tissue formation. However, the majority of the current strategies used to evaluate novel biomaterials focus on osteoblasts and bone formation, while osteoclasts are often overlooked. Consequently, there is limited knowledge on the interaction between osteoclasts and biomaterials. In this study, the ability of spongy-like gellan gum and hydroxyapatite-reinforced gellan gum hydrogels to support osteoclastogenesis was investigated in vitro. First, the spongy-like gellan gum and hydroxyapatite-reinforced gellan gum hydrogels were characterized in terms of microstructure, water uptake and mechanical properties. Then, bone marrow cells isolated from the long bones of mice and cultured in spongy-like hydrogels were treated with 1,25-dihydroxyvitamin D3 to promote osteoclastogenesis. It was shown that the addition of HAp to spongy-like gellan gum hydrogels enables the formation of larger pores and thicker walls, promoting an increase in stiffness. Hydroxyapatite-reinforced spongy-like gellan gum hydrogels support the formation of the aggregates of tartrate-resistant acid phosphatase-stained cells and the expression of genes encoding DC-STAMP and Cathepsin K, suggesting the differentiation of bone marrow cells into pre-osteoclasts. The hydroxyapatite-reinforced spongy-like gellan gum hydrogels developed in this work show promise for future use in bone tissue scaffolding applications.

Fibre Concrete 2017

NASA Astrophysics Data System (ADS)

2017-09-01

9th international conference on fibre reinforced concretes (FRC), textile reinforced concretes (TRC) and ultra-high performance concretes (UHPC) Preface The Fibre Concrete Conference series is held biennially to provide a platform to share knowledge on fibre reinforced concretes, textile concretes and ultra-high performance concretes regarding material properties and behaviour, technology procedures, topics of long-term behaviour, creep, durability; sustainable aspects of concrete including utilisation of waste materials in concrete production and recycling of concrete. The tradition of Fibre Concrete Conferences started in eighties of the last century. Nowadays the conference is organized by the Department of Concrete and Masonry Structures of the Czech Technical University in Prague, Faculty of Civil Engineering. The 9th International Conference Fibre Concrete 2017 had 109 participants from 27 countries all over the world. 55 papers were presented including keynote lectures of Professor Bažant, Professor Bartoš and Dr. Broukalová. The conference program covered wide range of topics from scientific research to practical applications. The presented contributions related to performance and behaviour of cement based composites, their long-term behaviour and durability, sustainable aspects, advanced analyses of structures from these composites and successful applications. This conference was organized also to honour Professor Zděnek P. Bažant on the occasion of his jubilee and to appreciate his merits and discoveries in the field of fibre reinforced composites, structural mechanics and engineering.

Allergic contact dermatitis from a nonbisphenol A epoxy in a graphite fiber reinforced epoxy laminate.

PubMed

Mathias, C G

1987-09-01

An employee of the Composites Division of an aircraft engine manufacturing firm developed dermatitis associated with the handling of a graphite fiber reinforced epoxy laminate (epoxy prepreg). Patch test investigation demonstrated that the responsible causal agent was the nonbisphenol A epoxy binder, 4-glycidyloxy-N, N-diglycidylaniline. A patch test with bisphenol A epoxy from a standard patch test screening series was negative. Subsequent interviews with employees of the Composites Division suggested that a relative lack of awareness of the cutaneous hazards of fiber reinforced epoxy laminates, compared with liquid epoxy resin systems, may be an important risk factor for allergic sensitization to these composite materials.

The application of cast SiC/Al to rotary engine components

NASA Technical Reports Server (NTRS)

Stoller, H. M.; Carluccio, J. R.; Norman, J. P.

1986-01-01

A silicon carbide reinforced aluminum (SiC/Al) material fabricated by Dural Aluminum Composites Corporation was tested for various components of rotary engines. Properties investigated included hardness, high temperature strength, wear resistance, fatigue resistance, thermal conductivity, and expansion. SiC/Al appears to be a viable candidate for cast rotors, and may be applicable to other components, primarily housings.

Access and Success for African American Engineers and Computer Scientists: A Case Study of Two Predominantly White Public Research Universities

ERIC Educational Resources Information Center

Newman, Christopher Bufford

2011-01-01

Over the past decade, three rationales have emerged for emphasizing the reinforcement of the United States' science, technology, engineering, and mathematics (STEM) pipeline. The first rationale pertains to U.S. global competitiveness, the second revolves around the benefits of a diverse workforce, and the third argument points to social justice…

Measuring the Silver Composition of Nanocolloids by Inductively Coupled Plasma-Optical Emission Spectroscopy: A Laboratory Experiment for Chemistry and Engineering Students

ERIC Educational Resources Information Center

Brittle, Seth W.; Baker, Joshua D.; Dorney, Kevin M.; Dagher, Jessica M.; Ebrahimian, Tala; Higgins, Steven R.; Pavel Sizemore, Ioana E.

2015-01-01

The increased worldwide exploitation of nanomaterials has reinforced the importance of introducing nanoscale aspects into the undergraduate and graduate curriculum. To meet this need, a novel nano-laboratory module was developed and successfully performed by science and engineering students. The main goal of the experiment was to accurately…

Reinforced chitosan-based heart valve scaffold and utility of bone marrow-derived mesenchymal stem cells for cardiovascular tissue engineering

NASA Astrophysics Data System (ADS)

Albanna, Mohammad Zaki

Recent research has demonstrated a strong correlation between the differentiation profile of mesenchymal stem cells (MSCs) and scaffold stiffness. Chitosan is being widely studied for tissue engineering applications due to its biocompatibility and biodegradability. However, its use in load-bearing applications is limited due to moderate to low mechanical properties. In this study, we investigated the effectiveness of a fiber reinforcement method for enhancing the mechanical properties of chitosan scaffolds. Chitosan fibers were fabricated using a solution extrusion and neutralization method and incorporated into porous chitosan scaffolds. The effects of different fiber/scaffold mass ratios, fiber mechanical properties and fiber lengths on scaffold mechanical properties were studied. The results showed that incorporating fibers improved scaffold strength and stiffness in proportion to the fiber/scaffold mass ratio. A fiber-reinforced heart valve leaflet scaffold achieved strength values comparable to the radial values of human pulmonary and aortic valves. Additionally, the effects of shorter fibers (2 mm) were found to be up to 3-fold greater than longer fibers (10 mm). Despite this reduction in fiber mechanical properties caused by heparin crosslinking, the heparin-modified fibers still improved the mechanical properties of the reinforced scaffolds, but to a lesser extent than the unmodified fibers. The results demonstrate that chitosan fiber-reinforcement can be used to generate tissue-matching mechanical properties in porous chitosan scaffolds and that fiber length and mechanical properties are important parameters in defining the degree of mechanical improvement. We further studied various chemical and physical treatments to improve the mechanical properties of chitosan fibers. With combination of chemical and physical treatments, fiber stiffness improved 40fold compared to unmodified fibers. We also isolated ovine bone marrow-derived MSCs and evaluated their utility for cardiovascular tissue engineering applications. Moreover, we evaluated the effect of various glycosaminoglycans (GAGs) on MSCs morphology and proliferation. Lastly, we studied the effect of stiffness of mechanically improved chitosan fibers on MSCs viability, attachment and proliferation. Results showed that MSCs proliferation improved in proportion to fiber stiffness.

Performance of Hydrophobisation Techniques in Case of Reinforced Concrete Structures

NASA Astrophysics Data System (ADS)

Błaszczyński, Tomasz; Osesek, Mateusz; Gwozdowski, Błażej; Ilski, Mirosław

2017-10-01

Concrete is, unchangeably, one of the most frequently applied building materials, also in the case of bridges, overpasses or viaducts. Along with the aging of such structures, the degradation of concrete, which may accelerate the corrosion of reinforcing steel and drastically decrease the load-bearing capacity of the structure, becomes an important issue. The paper analyzes the possibilities of using deep hydrophobisation in repairing reinforced concrete engineering structures. The benefits of properly securing reinforced concrete structures from the damaging effects of UV radiation, the influence of harmful gases, or progression of chlorine induced corrosion have been presented, especially in regards to bridge structures. The need to calculate the costs of carrying out investments along with the expected costs of maintaining such structures, as well as the high share of costs connected with logistics, has also been indicated in the total costs of repair works.

Analytical Modeling for Mechanical Strength Prediction with Raman Spectroscopy and Fractured Surface Morphology of Novel Coconut Shell Powder Reinforced: Epoxy Composites

NASA Astrophysics Data System (ADS)

Singh, Savita; Singh, Alok; Sharma, Sudhir Kumar

2017-06-01

In this paper, an analytical modeling and prediction of tensile and flexural strength of three dimensional micro-scaled novel coconut shell powder (CSP) reinforced epoxy polymer composites have been reported. The novel CSP has a specific mixing ratio of different coconut shell particle size. A comparison is made between obtained experimental strength and modified Guth model. The result shows a strong evidence for non-validation of modified Guth model for strength prediction. Consequently, a constitutive modeled equation named Singh model has been developed to predict the tensile and flexural strength of this novel CSP reinforced epoxy composite. Moreover, high resolution Raman spectrum shows that 40 % CSP reinforced epoxy composite has high dielectric constant to become an alternative material for capacitance whereas fractured surface morphology revealed that a strong bonding between novel CSP and epoxy polymer for the application as light weight composite materials in engineering.

Synthesis and Characterization of Multi Wall Carbon Nanotubes (MWCNT) Reinforced Sintered Magnesium Matrix Composites

NASA Astrophysics Data System (ADS)

Vijaya Bhaskar, S.; Rajmohan, T.; Palanikumar, K.; Bharath Ganesh Kumar, B.

2016-04-01

Metal matrix composites (MMCs) reinforced with ceramic nano particles (less than 100 nm), termed as metal matrix nano composites (MMNCs), can overcome those disadvantages associated with the conventional MMCs. MMCs containing carbon nanotubes are being developed and projected for diverse applications in various fields of engineering like automotive, avionic, electronic and bio-medical sectors. The present investigation deals with the synthesis and characterization of hybrid magnesium matrix reinforced with various different wt% (0-0.45) of multi wall carbon nano tubes (MWCNT) and micro SiC particles prepared through powder metallurgy route. Microstructure and mechanical properties such as micro hardness and density of the composites were examined. Microstructure of MMNCs have been investigated by scanning electron microscope, X-ray diffraction and energy dispersive X-ray spectroscopy (EDS) for better observation of dispersion of reinforcement. The results indicated that the increase in wt% of MWCNT improves the mechanical properties of the composite.

Friction and Wear Behavior of Carbon Fabric-Reinforced Epoxy Composites

NASA Astrophysics Data System (ADS)

Şahin, Y.; De Baets, Patrick

2017-12-01

Besides intrinsic material properties, weight/energy savings and wear performance play an important role in the selection of materials for any engineering application. The tribological behavior of carbon fabric-reinforced epoxy composites produced by molding technique was investigated using a reciprocating pin-on-plate configuration. It was shown that the wear rate considerably decreased (by a factor of approx. 8) with the introduction of the reinforcing carbon fabric into the epoxy matrix. It was observed that the wear rate of the tested composites increased with an increase in normal load. Moreover, the coefficient of friction for epoxy/steel and composites/steel tribo-pairs was also determined and decreased with increasing load. By means of scanning electron microscopy of the wear tracks, different wear mechanisms such as matrix wear, matrix fatigue and cracking, matrix debris formation for neat epoxy together with fabric/fiber thinning, fabric breakage and fabric/matrix debonding for the reinforced epoxy could be distinguished.

Cost Effectiveness of Precast Reinforced Concrete Roof Slabs

NASA Astrophysics Data System (ADS)

Parskiy, N. D.; Molodtsov, M. V.; Molodtsova, V. E.

2017-11-01

Engineers always seek to free interior space from intermediate supporting elements. Nowadays plants, being at the forefront of technology, produce a new generation of exclusive patented prefabricated reinforced concrete elements with a high load-bearing capacity, excellent heat resistance characteristics combined with the aesthetics and beauty. It is a system of Seagull Gabbiano prestressed roof slabs for the spans of 12m - 40m. The article shows the advantages of the Seagull slabs over conventional precast reinforced concrete and metal roof trusses. It also gives the analysis of the technical and economic indices of design and construction of a building with the Seagull slabs depending on the size of spans to cover. The use of structural systems with increased spans allows for the modern buildings and structures of prefabricated reinforced concrete with enhanced functionality and aesthetics alongside with a wide range of planning solutions.

Reinforcement of timber beams with carbon fibers reinforced plastics

NASA Astrophysics Data System (ADS)

Gugutsidze, G.; Draškovič, F.

2010-06-01

Wood is a polymeric material with many valuable features and which also lacks some negative features. In order to keep up with high construction rates and the minimization of negative effects, wood has become one of the most valuable materials in modern engineering. But the use of timber material economically is also an actual problem in order to protect the environment and improve natural surroundings. A panel of scientists is interested in solving these problems and in creating rational structures, where timber can be used efficiently. These constructions are as follows: glue-laminated (gluelam), composed and reinforced wooden constructions. Composed and reinforced wooden constructions are examined less, but according to researches already carried out, it is clear that significant work can be accomplished in creating rational, highly effective and economic timber constructions. The paper deals with research on the formation of composed fiber-reinforced beams (CFRP) made of timber and provide evidence of their effectiveness. The aim of the paper is to investigate cross-bending of CFRP-reinforced gluelaminated timber beams. According to the results we were able to determine the additional effectiveness of reinforcement with CFRP (which depends on the CFRP material's quality, quantity and module of elasticity) on the mechanical features of timber and a whole beam.

Strengthening steel bridge girders using CFRP.

DOT National Transportation Integrated Search

2010-06-01

While traditional retrofitting methods for steel bridge girders could be time consuming and uneconomical, an alternative repair method is suggested using Carbon Fiber Reinforced Polymers (CFRP) laminate strips, providing engineers with a competitive ...

Probabilistic design of fibre concrete structures

NASA Astrophysics Data System (ADS)

Pukl, R.; Novák, D.; Sajdlová, T.; Lehký, D.; Červenka, J.; Červenka, V.

2017-09-01

Advanced computer simulation is recently well-established methodology for evaluation of resistance of concrete engineering structures. The nonlinear finite element analysis enables to realistically predict structural damage, peak load, failure, post-peak response, development of cracks in concrete, yielding of reinforcement, concrete crushing or shear failure. The nonlinear material models can cover various types of concrete and reinforced concrete: ordinary concrete, plain or reinforced, without or with prestressing, fibre concrete, (ultra) high performance concrete, lightweight concrete, etc. Advanced material models taking into account fibre concrete properties such as shape of tensile softening branch, high toughness and ductility are described in the paper. Since the variability of the fibre concrete material properties is rather high, the probabilistic analysis seems to be the most appropriate format for structural design and evaluation of structural performance, reliability and safety. The presented combination of the nonlinear analysis with advanced probabilistic methods allows evaluation of structural safety characterized by failure probability or by reliability index respectively. Authors offer a methodology and computer tools for realistic safety assessment of concrete structures; the utilized approach is based on randomization of the nonlinear finite element analysis of the structural model. Uncertainty of the material properties or their randomness obtained from material tests are accounted in the random distribution. Furthermore, degradation of the reinforced concrete materials such as carbonation of concrete, corrosion of reinforcement, etc. can be accounted in order to analyze life-cycle structural performance and to enable prediction of the structural reliability and safety in time development. The results can serve as a rational basis for design of fibre concrete engineering structures based on advanced nonlinear computer analysis. The presented methodology is illustrated on results from two probabilistic studies with different types of concrete structures related to practical applications and made from various materials (with the parameters obtained from real material tests).

Environmental durability of graphite.

DOT National Transportation Integrated Search

2002-01-01

The increasing acceptance and incorporation of fiber-reinforced polymer matrix composites (PMCs) as engineering construction materials have led many to look to the infrastructure as an application for these versatile materials. One such system is pul...

ODOT research news : summer quarter 2002.

DOT National Transportation Integrated Search

2002-01-01

The newsletter includes: : 1) High School Student Apprentices with Research; : 2) Summer Work for Engineering Student; : 3) WASHTO-X is Underway; : 4) Shear Capacity Assessment of Corrosion-Damaged, Reinforced Concrete Beams; : 5) Railroad Crossing I...

Engineering fabrics in transportation construction

NASA Astrophysics Data System (ADS)

Herman, S. C.

1983-11-01

The following areas are discussed: treatments for reduction of reflective cracking of asphalt overlays on jointed-concrete pavements in Georgia; laboratory testing of fabric interlayers for asphalt concrete paving: interim report; reflection cracking models: review and laboratory evaluation of engineering fabrics; optimum-depth method for design of fabric-reinforced unsurfaced roads; dynamic test to predict field behavior of filter fabrics used in pavement subdrains; mechanism of geotextile performance in soil-fabric systems for drainage and erosion control; permeability tests of selected filter fabrics for use with a loess-derived alluvium; geotextile filter criteria; use of fabrics for improving the placement of till on peat foundation; geotextile earth-reinforced retaining wall tests: Glenwood Canyon, Colorado; New York State Department of Transportation's experience and guidelines for use of geotextiles; evaluation of two geotextile installations in excess of a decade old; and, long-term in situ properties of geotextiles.

Development of ricehusk ash reinforced bismaleimide toughened epoxy nanocomposites.

NASA Astrophysics Data System (ADS)

K, Kanimozhi; Sethuraman, K.; V, Selvaraj; Alagar, Muthukaruppan

2014-09-01

Abstract Recent past decades have witnessed remarkable advances in composites with potential applications in biomedical devices, aerospace, textiles, civil engineering, energy, electronic engineering, and household products. Thermoset polymer composites have further enhanced and broadened the area of applications of composites. In the present work epoxy-BMI toughened-silica hybrid (RHA/DGEBA-BMI) was prepared using bismaleimide as toughener, bisphenol-A as matrix and a silica precursor derived from rice husk ash as reinforcement with glycidoxypropyltrimethoxysilane as coupling agent. Differential scanning calorimetry, electron microscopy, thermogravimetric analysis, and goniometry were used to characterize RHA/DGEBA-BMI composites developed in the present work. Tensile, impact and flexural strength, tensile and flexural modulus, hardness, dielectric properties were also studied and discussed. The hybrid nanocomposites possess the higher values of the glass transition temperature (Tg) and mechanical properties than those of neat epoxy matrix.

Development of ricehusk ash reinforced bismaleimide toughened epoxy nanocomposites

PubMed Central

Kanimozhi, K.; Sethuraman, K.; Selvaraj, V.; Alagar, M.

2014-01-01

Recent past decades have witnessed remarkable advances in composites with potential applications in biomedical devices, aerospace, textiles, civil engineering, energy, electronic engineering, and household products. Thermoset polymer composites have further enhanced and broadened the area of applications of composites. In the present work epoxy-BMI toughened-silica hybrid (RHA/DGEBA-BMI) was prepared using bismaleimide as toughener, bisphenol-A as matrix and a silica precursor derived from rice husk ash as reinforcement with glycidoxypropyltrimethoxysilane as coupling agent. Differential scanning calorimetry, electron microscopy, thermogravimetric analysis, and goniometry were used to characterize RHA/DGEBA-BMI composites developed in the present work. Tensile, impact and flexural strength, tensile and flexural modulus, hardness, dielectric properties were also studied and discussed. The hybrid nanocomposites possess the higher values of the glass transition temperature (Tg) and mechanical properties than those of neat epoxy matrix. PMID:25279372

An Analysis of First Year Engineering Students' Satisfaction with a Support Distance Learning Program in Mathematics

ERIC Educational Resources Information Center

Matzakos, Nikolaos M.; Kalogiannakis, Michail

2018-01-01

An online support distance-learning program in Mathematics was developed to aid first year engineering students for their transition from the secondary to the tertiary education in order to reinforce deficiencies they may have in mathematical knowledge. The aim of the present study is to examine, firstly, to what extent the attendance of such a…

Impact resonance method for damage detection in RC beams strengthened with composites

NASA Astrophysics Data System (ADS)

Gheorghiu, Catalin; Rhazi, Jamal E.; Labossiere, Pierre

2005-05-01

There are numerous successful applications of fibre-reinforced composites for strengthening the civil engineering infrastructure. Most of these repairs are being continuously or intermittently monitored for assessing their effectiveness and safety. The impact resonance method (IRM), a non-destructive technique, utilized in civil engineering exclusively for determining the dynamic concrete properties, could be a valuable and viable damage detection tool for structural elements. The IRM gives useful information about the dynamic characteristics of rectangular and circular concrete members such as beams and columns. In this experimental program, a 1.2-m-long reinforced concrete beam strengthened with a carbon fibre-reinforced polymer (CFRP) plate has been employed. The CFRP-strengthened beam has been loaded in fatigue for two million cycles at 3 Hz. The load amplitude was from 15 to 35% of the anticipated yielding load of the beam. Throughout fatigue testing the cycling was stopped for IRM measurements to be taken. The obtained data provided information about changes in modal properties such as natural frequencies of vibration. These results have shown the successful use of the IRM for detecting fatigue damage in concrete members strengthened with composites.

Wear performance of garnet aluminium composites at high contact pressure

NASA Astrophysics Data System (ADS)

Sharma, Anju; Arora, Rama; Kumar, Suresh; Singh, Gurmel; Pandey, O. P.

2016-05-01

To satisfy the needs of the engineering sector, researchers and material scientists in this area adopted the development of composites with tailor made properties to enhance efficiency and cost savings in the manufacturing sector. The technology of the mineral industry is shaping the supply and demand of minerals derived materials. The composites are best classified as high performance materials have high strength-to-weight ratios, and require controlled manufacturing environments for optimum performance. Natural mineral garnet was used as the reinforcement of composite because of satisfactory mechanical properties as well as an attractive ecological alternative to others ceramics. For this purpose, samples have been prepared with different sizesof the garnet reinforcement using the mechanical stirring method to achieve the homogeneously dispersed strengthening phase. A systematic study of the effect of high contact pressure on the sliding wear behaviour of garnet reinforced LM13 alloy composites is presented in this paper. The SEM analysis of the worn samples and debris reveals the clues about the wear mechanism. The drastic improvement in the wear resistance of the composites at high contact pressure shows the high potential of the material to be used in engineering applications.

Magnesia-Based Cements: A Journey of 150 Years, and Cements for the Future?

PubMed

Walling, Sam A; Provis, John L

2016-04-13

This review examines the detailed chemical insights that have been generated through 150 years of work worldwide on magnesium-based inorganic cements, with a focus on both scientific and patent literature. Magnesium carbonate, phosphate, silicate-hydrate, and oxysalt (both chloride and sulfate) cements are all assessed. Many such cements are ideally suited to specialist applications in precast construction, road repair, and other fields including nuclear waste immobilization. The majority of MgO-based cements are more costly to produce than Portland cement because of the relatively high cost of reactive sources of MgO and do not have a sufficiently high internal pH to passivate mild steel reinforcing bars. This precludes MgO-based cements from providing a large-scale replacement for Portland cement in the production of steel-reinforced concretes for civil engineering applications, despite the potential for CO2 emissions reductions offered by some such systems. Nonetheless, in uses that do not require steel reinforcement, and in locations where the MgO can be sourced at a competitive price, a detailed understanding of these systems enables their specification, design, and selection as advanced engineering materials with a strongly defined chemical basis.

Numerical analysis of dynamic behavior of pre-stressed shape memory alloy concrete beam-column joints

NASA Astrophysics Data System (ADS)

Yan, S.; Xiao, Z. F.; Lin, M. Y.; Niu, J.

2018-04-01

Beam-column joints are important parts of a main frame structure. Mechanical properties of beam-column joints have a great influence on dynamic performances of the frame structure. Shape memory alloy (SMA) as a new type of intelligent metal materials has wide applications in civil engineering. The paper aims at proposing a novel beam-column joint reinforced with pre-stressed SMA tendons to increase its dynamic performance. Based on the finite element analysis (FEA) software ABAQUS, a numerical simulation for 6 beam-column scaled models considering different SMA reinforcement ratios and pre-stress levels was performed, focusing on bearing capacities, energy-dissipation and self-centering capacities, etc. These models were numerically tested under a pseudo-static load on the beam end, companying a constant vertical compressive load on the top of the column. The numerical results show that the proposed SMA-reinforced joint has a significantly increased bearing capacity and a good self-centering capability after unloading even though the energy-dissipation capacity becomes smaller due the less residual deformation. The concept and mechanism of the novel joint can be used as an important reference for civil engineering applications.

Simultaneous vibration control and energy harvesting using actor-critic based reinforcement learning

NASA Astrophysics Data System (ADS)

Loong, Cheng Ning; Chang, C. C.; Dimitrakopoulos, Elias G.

2018-03-01

Mitigating excessive vibration of civil engineering structures using various types of devices has been a conspicuous research topic in the past few decades. Some devices, such as electromagnetic transducers, which have a capability of exerting control forces while simultaneously harvesting energy, have been proposed recently. These devices make possible a self-regenerative system that can semi-actively mitigate structural vibration without the need of external energy. Integrating mechanical, electrical components, and control algorithms, these devices open up a new research domain that needs to be addressed. In this study, the feasibility of using an actor-critic based reinforcement learning control algorithm for simultaneous vibration control and energy harvesting for a civil engineering structure is investigated. The actor-critic based reinforcement learning control algorithm is a real-time, model-free adaptive technique that can adjust the controller parameters based on observations and reward signals without knowing the system characteristics. It is suitable for the control of a partially known nonlinear system with uncertain parameters. The feasibility of implementing this algorithm on a building structure equipped with an electromagnetic damper will be investigated in this study. Issues related to the modelling of learning algorithm, initialization and convergence will be presented and discussed.

Evaluation of creative problem-solving abilities in undergraduate structural engineers through interdisciplinary problem-based learning

NASA Astrophysics Data System (ADS)

McCrum, Daniel Patrick

2017-11-01

For a structural engineer, effective communication and interaction with architects cannot be underestimated as a key skill to success throughout their professional career. Structural engineers and architects have to share a common language and understanding of each other in order to achieve the most desirable architectural and structural designs. This interaction and engagement develops during their professional career but needs to be nurtured during their undergraduate studies. The objective of this paper is to present the strategies employed to engage higher order thinking in structural engineering students in order to help them solve complex problem-based learning (PBL) design scenarios presented by architecture students. The strategies employed were applied in the experimental setting of an undergraduate module in structural engineering at Queen's University Belfast in the UK. The strategies employed were active learning to engage with content knowledge, the use of physical conceptual structural models to reinforce key concepts and finally, reinforcing the need for hand sketching of ideas to promote higher order problem-solving. The strategies employed were evaluated through student survey, student feedback and module facilitator (this author) reflection. The strategies were qualitatively perceived by the tutor and quantitatively evaluated by students in a cross-sectional study to help interaction with the architecture students, aid interdisciplinary learning and help students creatively solve problems (through higher order thinking). The students clearly enjoyed this module and in particular interacting with structural engineering tutors and students from another discipline.

Basalt fiber reinforced porous aggregates-geopolymer based cellular material

NASA Astrophysics Data System (ADS)

Luo, Xin; Xu, Jin-Yu; Li, Weimin

2015-09-01

Basalt fiber reinforced porous aggregates-geopolymer based cellular material (BFRPGCM) was prepared. The stress-strain curve has been worked out. The ideal energy-absorbing efficiency has been analyzed and the application prospect has been explored. The results show the following: fiber reinforced cellular material has successively sized pore structures; the stress-strain curve has two stages: elastic stage and yielding plateau stage; the greatest value of the ideal energy-absorbing efficiency of BFRPGCM is 89.11%, which suggests BFRPGCM has excellent energy-absorbing property. Thus, it can be seen that BFRPGCM is easy and simple to make, has high plasticity, low density and excellent energy-absorbing features. So, BFRPGCM is a promising energy-absorbing material used especially in civil defense engineering.

Adaptive Crack Modeling with Interface Solid Elements for Plain and Fiber Reinforced Concrete Structures.

PubMed

Zhan, Yijian; Meschke, Günther

2017-07-08

The effective analysis of the nonlinear behavior of cement-based engineering structures not only demands physically-reliable models, but also computationally-efficient algorithms. Based on a continuum interface element formulation that is suitable to capture complex cracking phenomena in concrete materials and structures, an adaptive mesh processing technique is proposed for computational simulations of plain and fiber-reinforced concrete structures to progressively disintegrate the initial finite element mesh and to add degenerated solid elements into the interfacial gaps. In comparison with the implementation where the entire mesh is processed prior to the computation, the proposed adaptive cracking model allows simulating the failure behavior of plain and fiber-reinforced concrete structures with remarkably reduced computational expense.

Adaptive Crack Modeling with Interface Solid Elements for Plain and Fiber Reinforced Concrete Structures

PubMed Central

Zhan, Yijian

2017-01-01

The effective analysis of the nonlinear behavior of cement-based engineering structures not only demands physically-reliable models, but also computationally-efficient algorithms. Based on a continuum interface element formulation that is suitable to capture complex cracking phenomena in concrete materials and structures, an adaptive mesh processing technique is proposed for computational simulations of plain and fiber-reinforced concrete structures to progressively disintegrate the initial finite element mesh and to add degenerated solid elements into the interfacial gaps. In comparison with the implementation where the entire mesh is processed prior to the computation, the proposed adaptive cracking model allows simulating the failure behavior of plain and fiber-reinforced concrete structures with remarkably reduced computational expense. PMID:28773130

Evaluation of low-cost aluminum composites for aircraft engine structural applications

NASA Technical Reports Server (NTRS)

Mcdanels, D. L.; Signorelli, R. A.

1983-01-01

Panels of discontinuous SiC composites, with several aluminum matrices, were fabricated and evaluated. Modulus, yield strength and tensile strength results indicated that the properties of composites containing SiC whisker, nodule or particulate reinforcements were similar. The modulus of the composites was controlled by the volume percentage of the SiC reinforcement content, while the strength and ductility were controlled by both the reinforcement content and the matrix alloy. The feasibility of fabricating structural shapes by both wire performs and direct casting was demonstrated for Al2O3/Al composites. The feasibility of fabricating high performance composites into structural shapes by low pressure hot molding was demonstrated for B4C-coated B/Al composites.

Lincoln Advanced Science and Engineering Reinforcement (LASER) program

NASA Technical Reports Server (NTRS)

Williams, Willie E.

1989-01-01

Lincoln University, under the Lincoln Advanced Science and Engineering Reinforcement (LASER) Program, has identified and successfully recruited over 100 students for majors in technical fields. To date, over 70 percent of these students have completed or will complete technical degrees in engineering, physics, chemistry, and computer science. Of those completing the undergraduate degree, over 40 percent have gone on to graduate and professional schools. This success is attributable to well planned approaches to student recruitment, training, personal motivation, retention, and program staff. Very closely coupled to the above factors is a focus designed to achieve excellence in program services and student performance. Future contributions by the LASER Program to the pool of technical minority graduates will have a significant impact. This is already evident from the success of the students that began the first year of the program. With program plans to refine many of the already successful techniques, follow-on activities are expected to make even greater contributions to the availability of technically trained minorities. For example, undergraduate research exposure, broadened summer, and co-op work experiences will be enhanced.

Fiber reinforced superalloys for rocket engines

NASA Technical Reports Server (NTRS)

Petrasek, Donald W.; Stephens, Joseph R.

1989-01-01

High pressure turbopumps for advanced reusable liquid propellant rocket engines such as that for the Space Shuttle Main Engine (SSME) require turbine blade materials that operate under extreme conditions of temperature, hydrogen environment, high-cycle fatigue loading, thermal fatigue and thermal shock. Such requirements tax the capabilities of current blade materials. Based on projections of properties for tungsten fiber reinforced superalloy (FRS) composites, it was concluded that FRS turbine blades offer the potential of a several fold increase in life and over a 200 C increase in temperature capability over the current SSME blade material. FRS composites were evaluated with respect to mechanical property requirements for SSME blade applications. Compared to the current blade material, the thermal shock resistance of FRS materials is excellent, two to nine times better, and their thermal fatigue resistance is equal to or higher than the current blade material. FRS materials had excellent low and high-cycle fatigue strengths, and thermal shock-induced surface microcracks had no influence on their fatigue strength. The material also exhibited negligible embrittlement when exposed to a hydrogen environment.

Fiber reinforced superalloys for rocket engines

NASA Technical Reports Server (NTRS)

Petrasek, Donald W.; Stephens, Joseph R.

1988-01-01

High-pressure turbopumps for advanced reusable liquid-propellant rocket engines such as that for the Space Shuttle Main Engine (SSME) require turbine blade materials that operate under extreme conditions of temperature, hydrogen environment, high-cycle fatigue loading, thermal fatigue and thermal shock. Such requirements tax the capabilities of current blade materials. Based on projections of properties for tungsten fiber reinforced superalloy (FRS) composites, it was concluded that FRS turbine blades offer the potential of a several-fold increase in life and over a 200C increase in temperature capability over current SSME blade material. FRS composites were evaluated with respect to mechanical property requirements for SSME blade applications. Compared to the current blade material, the thermal shock resistance of FRS materials is excellent, two to nine times better, and their thermal fatigue resistance is equal to or higher than the current blade material. FRS materials had excellent low and high-cycle fatigue strengths, and thermal shock-induced surface microcracks had no influence on their fatigue strength. The material also exhibited negligible embrittlement when exposed to a hydrogen environment.

A Combustion Laboratory for Undergraduates.

ERIC Educational Resources Information Center

Peters, James E.

1985-01-01

Describes a combustion laboratory facility and experiments for a senior-level (undergraduate) course in mechanical engineering. The experiment reinforces basic thermodynamic concepts and provides many students with their first opportunity to work with a combustion system. (DH)

Development of hand-held thermographic inspection technologies.

DOT National Transportation Integrated Search

2009-08-01

Subsurface deterioration in concrete structures presents a significant challenge for inspection and maintenance engineers. Cracking, delaminations and spalling that can occur as a result of corrosion of embedded reinforcing steel can lead to pot hole...

MC-1 Engine Valves, Lessons Learned

NASA Technical Reports Server (NTRS)

Laszar, John

2003-01-01

Many lessons were learned during the development of the valves for the MC-1 engine. The purpose of this report is to focus on a variety of issues related to the engine valves and convey the lessons learned. This paper will not delve into detailed technical analysis of the components. None of the lessons learned are new or surprising, but simply reinforce the importance of addressing the details of the design early, at the component level. The Marshall Space Flight Center (MSFC), Huntsville, Alabama developed the MC-1 engine, a LOX / FW-1, 60,000 pound thrust engine. This engine was developed under the Low Cost Boost Technology office at MSFC and proved to be a very successful project for the MSFC Propulsion team and the various subcontractors working the development of the engine and its components.

9. Credit JPL. Photographic copy of drawing, engineering drawing showing ...

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

9. Credit JPL. Photographic copy of drawing, engineering drawing showing structure of Test Stand 'A' (Building 4202/E-3) and its relationship to the Monitor Building or blockhouse (Building 4203/E-4) when a reinforced concrete machinery room was added to the west side of Test Stand 'A' in 1955. California Institute of Technology, Jet Propulsion Laboratory, Plant Engineering 'Electrical Layout - Muroc, Test Stand & Refrigeration Equipment Room,' drawing no. E3/7-0, April 6, 1955. - Jet Propulsion Laboratory Edwards Facility, Test Stand A, Edwards Air Force Base, Boron, Kern County, CA

Engineering Provision of Assault Crossing of Rivers,

DTIC Science & Technology

1983-01-21

in the first place, in the missile and nuclear weapons warfare sharply they increased frontage and the depth of troop dispositions in the defense...modern missile and nuclear weapons warfare the medium * and wide rivers, reinforced by mine fields and decomposition of water-engineering and other...PMP and transport motor pool PVD -20. The existing pontoon trains make it possible to mechanize labor-consuming fitters work, to the minimum to bring

Summary of Research 1997, Department of Mechanical Engineering.

DTIC Science & Technology

1999-01-01

Maintenance for Diesel Engines 49 Control Architectures and Non-Linear Controllers for Unmanned Underwater Vehicles 38 Creep of Fiber Reinforced Metal...Technology Demonstration (ATD) 50 Development of Delphi Visual Performance Model 25 Diffraction Methods for the Accurate Measurement of Structure Factors...literature. If this could be done, a U.S. version of ORACLE (to be called DELPHI ) could be developed and used. The result has been the development of a

The automotive application of discontinuously reinforced TiB-Ti composites

NASA Astrophysics Data System (ADS)

Saito, Takashi

2004-05-01

In 1998, Toyota Motor Corporation adopted intake valves and exhaust valves made of titanium-based alloys for the engine of its Altezza. Both valves were manufactured via a newly developed cost-effective powder metallurgy process. The exhaust valve is made of a newly developed titanium metal-matrix composite (MMC). The valve has achieved sufficient durability and reliability with a manufacturing cost acceptable for the mass-produced automobile engine components.

Abstracts, 21st Annual Meeting Society of Engineering Science, Inc., October 15, 16 and 17, 1984.

DTIC Science & Technology

1984-01-01

ANALYSIS OF ADHESIVE JOINTS IN FIBER REINFORCED COMPOSITES by C. Burger*, D. Mallik **, A. Voloshin* and S. Mahadevan* *Department of Engineering Science...N. 33 (15A,44)Halkus, D.S. 301 ( 16 PM6) Olaosebikan, L. 89,95 (15PM2) Mallik , D. 356 (17AH2) Olhoff, N. 456,459 (l7PM4)Malone, J.B. 128 (15PM5

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

NASA Image and Video Library

2003-09-26

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

Return to Flight Resource Reel 1 of 2

NASA Technical Reports Server (NTRS)

2005-01-01

A video presentation detailing the tests performed on the Space Shuttle Discovery in preparation for its return to flight is shown. The tests include: 1) Reinforced Carbon-Carbon (RCC) Impact Test Article; 2) RCC Foam Impact Testing; 3) Thermal Protection System (TPS) Ice Impact Testing featuring Justin Kerr, Project Engineer; 4) Wing Leading Edge Wireless Sensors featuring Karl Kiefer, President and CEO of Invocon, and Kevin Champaigne of Invocon; 5) TPS Repair Testing KC-135 Zero-G Environment featuring Soichi Noguchi, Mission Specialist; 6) TPS Extravehicular Activity Tool Demonstration; 7) TPS Repair Testing Vacuum Glove box; 8) TPS Repair Testing Human Thermal Vacuum Chamber; 9) TPS Reentry Testing Atmospheric Reentry Materials and Structures Evaluation Facility; 10) TPS Alternative Repair Concept; 11) Lora Bailey Lead Engineer for EVA Tools; 12) Reinforced Carbon-Carbon ATK Thiokol Plug Repair Animation; 13) 3-Percent Model Build-Up; and 14) Wind Tunnel Testing RCC Aging Research Ballistic Testing.

On the Theory and Numerical Simulation of Cohesive Crack Propagation with Application to Fiber-Reinforced Composites

NASA Technical Reports Server (NTRS)

Rudraraju, Siva Shankar; Garikipati, Krishna; Waas, Anthony M.; Bednarcyk, Brett A.

2013-01-01

The phenomenon of crack propagation is among the predominant modes of failure in many natural and engineering structures, often leading to severe loss of structural integrity and catastrophic failure. Thus, the ability to understand and a priori simulate the evolution of this failure mode has been one of the cornerstones of applied mechanics and structural engineering and is broadly referred to as "fracture mechanics." The work reported herein focuses on extending this understanding, in the context of through-thickness crack propagation in cohesive materials, through the development of a continuum-level multiscale numerical framework, which represents cracks as displacement discontinuities across a surface of zero measure. This report presents the relevant theory, mathematical framework, numerical modeling, and experimental investigations of through-thickness crack propagation in fiber-reinforced composites using the Variational Multiscale Cohesive Method (VMCM) developed by the authors.

Development and fabrication of high strength alloy fibers for use in metal-metal matrix composites

NASA Technical Reports Server (NTRS)

King, G. W.; Petrasek, D. W.

1979-01-01

Metal fiber reinforced superalloys are being considered for construction of critical components in turbine engines that operate at high temperature. The problems involved in fabricating refractory metal alloys into wire form in such a manner as to maximize their strength properties without developing excessive structural defects are described. The fundamental principles underlying the development of such alloy fibers are also briefly discussed. The progress made to date in developing tungsten, tantalum and columbium base alloys for fiber reinforcement is reported and future prospects for alloy fiber development considered.

Composite Material Application to Liquid Rocket Engines

NASA Technical Reports Server (NTRS)

Judd, D. C.

1982-01-01

The substitution of reinforced plastic composite (RPC) materials for metal was studied. The major objectives were to: (1) determine the extent to which composite materials can be beneficially used in liquid rocket engines; (2) identify additional technology requirements; and (3) determine those areas which have the greatest potential for return. Weight savings, fabrication costs, performance, life, and maintainability factors were considered. Two baseline designs, representative of Earth to orbit and orbit to orbit engine systems, were selected. Weight savings are found to be possible for selected components with the substitution of materials for metal. Various technology needs are identified before RPC material can be used in rocket engine applications.

Development of a CFRP Engine Thrust Frame for the Next Generation Launchers

NASA Astrophysics Data System (ADS)

Fatemi, Javad; van der Bas, Finn; Cruijssen, Henk

2012-07-01

This paper addresses the activities related to the development of technologies for a composite Engine Thrust Frame (ETF) for the next generation launchers. In particular, the design and analyses of a full Carbon Fibre Reinforced Plastic (CFRP) engine thrust frame are presented in more detail. The ETF concept is composed of three main parts, i.e. an aluminium top-ring which connects the ETF to the upper-stage tank, a CFRP cone, and a CFRP cone-cap which connects the Vinci engine to the ETF. The main challenging requirements for development of a CFRP ETF are recalled. The ETF concept and its mechanical performances are assessed.

Particle-Based Geometric and Mechanical Modelling of Woven Technical Textiles and Reinforcements for Composites

NASA Astrophysics Data System (ADS)

Samadi, Reza

Technical textiles are increasingly being engineered and used in challenging applications, in areas such as safety, biomedical devices, architecture and others, where they must meet stringent demands including excellent and predictable load bearing capabilities. They also form the bases for one of the most widespread group of composite materials, fibre reinforced polymer-matrix composites (PMCs), which comprise materials made of stiff and strong fibres generally available in textile form and selected for their structural potential, combined with a polymer matrix that gives parts their shape. Manufacturing processes for PMCs and technical textiles, as well as parts and advanced textile structures must be engineered, ideally through simulation, and therefore diverse properties of the textiles, textile reinforcements and PMC materials must be available for predictive simulation. Knowing the detailed geometry of technical textiles is essential to predicting accurately the processing and performance properties of textiles and PMC parts. In turn, the geometry taken by a textile or a reinforcement textile is linked in an intricate manner to its constitutive behaviour. This thesis proposes, investigates and validates a general numerical tool for the integrated and comprehensive analysis of textile geometry and constitutive behaviour as required toward engineering applications featuring technical textiles and textile reinforcements. The tool shall be general with regards to the textiles modelled and the loading cases applied. Specifically, the work aims at fulfilling the following objectives: 1) developing and implementing dedicated simulation software for modelling textiles subjected to various load cases; 2) providing, through simulation, geometric descriptions for different textiles subjected to different load cases namely compaction, relaxation and shear; 3) predicting the constitutive behaviour of the textiles undergoing said load cases; 4) identifying parameters affecting the textile geometry and constitutive behaviour under evolving loading; 5) validating simulation results with experimental trials; and 6) demonstrating the applicability of the simulation procedure to textile reinforcements featuring large numbers of small fibres as used in PMCs. As a starting point, the effects of reinforcement configuration on the in-plane permeability of textile reinforcements, through-thickness thermal conductivity of PMCs and in-plane stiffness of unidirectional and bidirectional PMCs were quantified systematically and correlated with specific geometric parameters. Variability was quantified for each property at a constant fibre volume fraction. It was observed that variability differed strongly between properties; as such, the simulated behaviour can be related to variability levels seen in experimental measurements. The effects of the geometry of textile reinforcements on the aforementioned processing and performance properties of the textiles and PMCs made from these textiles was demonstrated and validated, but only for simple cases as thorough and credible geometric models were not available at the onset of this work. Outcomes of this work were published in a peer-reviewed journal [101]. Through this thesis it was demonstrated that predicting changes in textile geometry prior and during loading is feasible using the proposed particle-based modelling method. The particle-based modelling method relies on discrete mechanics and offers an alternative to more traditional methods based on continuum mechanics. Specifically it alleviates issues caused by large strains and management of intricate, evolving contact present in finite element simulations. The particle-based modelling method enables credible, intricate modelling of the geometry of textiles at the mesoscopic scale as well as faithful mechanical modelling under load. Changes to textile geometry and configuration due to the normal compaction pressure, stress relaxation, in-plane shear and other types of loads were successfully predicted.

Mechanical enhancement and in vitro biocompatibility of nanofibrous collagen-chitosan scaffolds for tissue engineering.

PubMed

Zou, Fengjuan; Li, Runrun; Jiang, Jianjun; Mo, Xiumei; Gu, Guofeng; Guo, Zhongwu; Chen, Zonggang

2017-12-01

The collagen-chitosan complex with a three-dimensional nanofiber structure was fabricated to mimic native ECM for tissue repair and biomedical applications. Though the three-dimensional hierarchical fibrous structures of collagen-chitosan composites could provide more adequate stimulus to facilitate cell adhesion, migrate and proliferation, and thus have the potential as tissue engineering scaffolding, there are still limitations in their applications due to the insufficient mechanical properties of natural materials. Because poly (vinyl alcohol) (PVA) and thermoplastic polyurethane (TPU) as biocompatible synthetic polymers can offer excellent mechanical properties, they were introduced into the collagen-chitosan composites to fabricate the mixed collagen/chitosan/PVA fibers and a sandwich structure (collagen/chitosan-TPU-collagen/chitosan) of nanofiber in order to enhance the mechanical properties of the nanofibrous collagen-chitosan scaffold. The results showed that the tensile behavior of materials was enhanced to different degrees with the difference of collagen content in the fibers. Besides the Young's modulus had no obvious changes, both the break strength and the break elongation of materials were heightened after reinforced by PVA. For the collagen-chitosan nanofiber reinforced by TPU, both the break strength and the Young's modulus of materials were heightened in different degrees with the variety of collagen content in the fibers despite the decrease of the break elongation of materials to some extent. In vitro cell test demonstrated that the materials could provide adequate environment for cell adhesion and proliferation. All these indicated that the reinforced collagen-chitosan nanofiber could be as potential scaffold for tissue engineering according to the different mechanical requirements in clinic.

Evaluation of mechanical properties of hybrid fiber (hemp, jute, kevlar) reinforced composites

NASA Astrophysics Data System (ADS)

Suresha, K. V.; Shivanand, H. K.; Amith, A.; Vidyasagar, H. N.

2018-04-01

In today's world composites play wide role in all the engineering fields. The reinforcement of composites decides the properties of the material. Natural fiber composites compared to synthetic fiber possesses poor mechanical properties. The solution for this problem is to use combination of natural fiber and synthetic fiber. Hybridization helps to improve the overall mechanical properties of the material. In this study, hybrid reinforced composites of Hemp fabric/Kevlar fabric/Epoxy and Jute fabric/ Kevlar fabric/Epoxy composites are fabricated using Simple hand layup technique followed by Vacuum bagging process. Appropriate test methods as per standards and guidelines are followed to analyze mechanical behavior of the composites. The mechanical characteristics like tensile, compression and flexural properties of the hybrid reinforced composites are tested as per the ASTM standards by series of tensile test; compression test and three point bending tests were conducted on the hybrid composites. A quantitative relationship between the Hemp fabric/Kevlar fabric/Epoxy and Jute/ Kevlar fabric/Epoxy has been established with constant thickness.

Energy-momentum conserving higher-order time integration of nonlinear dynamics of finite elastic fiber-reinforced continua

NASA Astrophysics Data System (ADS)

Erler, Norbert; Groß, Michael

2015-05-01

Since many years the relevance of fibre-reinforced polymers is steadily increasing in fields of engineering, especially in aircraft and automotive industry. Due to the high strength in fibre direction, but the possibility of lightweight construction, these composites replace more and more traditional materials as metals. Fibre-reinforced polymers are often manufactured from glass or carbon fibres as attachment parts or from steel or nylon cord as force transmission parts. Attachment parts are mostly subjected to small strains, but force transmission parts usually suffer large deformations in at least one direction. Here, a geometrically nonlinear formulation is necessary. Typical examples are helicopter rotor blades, where the fibres have the function to stabilize the structure in order to counteract large centrifugal forces. For long-run analyses of rotor blade deformations, we have to apply numerically stable time integrators for anisotropic materials. This paper presents higher-order accurate and numerically stable time stepping schemes for nonlinear elastic fibre-reinforced continua with anisotropic stress behaviour.

NiAl-base composite containing high volume fraction of AlN for advanced engines

NASA Technical Reports Server (NTRS)

Hebsur, Mohan (Inventor); Whittenbeger, John D. (Inventor); Lowell, Carl F. (Inventor)

1994-01-01

A particulate reinforced NiAl-AlN composite alloy has a NiAl matrix and greater than about 13 volume percent fine particles of AlN within the matrix. The particles preferably have a diameter from about 15 nanometers to about 50 nanometers. The particulate reinforced NiAl-AlN composite alloy may be prepared by cryomilling prealloyed NiAl in liquid nitrogen using grinding media having a diameter of from about 2 to 6 mm at an impeller speed of from about 450 RPM to about 800 RPM. The cryomilling may be done for a duration of from about 4 hours to about 20 hours to obtain a cryomilled powder. The cryomilled powder may be consolidated to form the particulate reinforced NiAl-AlN composite alloy. The particulate reinforced alloy can further include a toughening alloy. The toughening alloy may include NiCrAlY, FeCrAlY, and FeAl.

Nial-base composite containing high volume fraction of AlN for advanced engines

NASA Technical Reports Server (NTRS)

Hebsur, Mohan G. (Inventor); Whittenberger, John D. (Inventor); Lowell, Carl E. (Inventor)

1997-01-01

A particulate reinforced NiAl-AlN composite alloy has a NiAl matrix and greater than about 13 volume percent fine particles of AlN within the matrix. The particles preferably have a diameter from about 15 nanometers to about 50 nanometers. The particulate reinforced NiAl-AlN composite alloy may be prepared by cryomilling prealloyed NiAl in liquid nitrogen using grinding media having a diameter of from about 2 mm to about 6 mm at an impeller speed of from about 450 RPM to about 800 RPM. The cryomilling may be done for a duration of from about 4 hours to about 20 hours to obtain a cryomilled powder. The cryomilled powder may be consolidated to form the particulate reinforced NiAl-AlN composite alloy. The particulate reinforced alloy can further include a toughening alloy. The toughening alloy may include NiCrAlY, FeCrAY and FeAl.

Seismic response of reinforced concrete frames at different damage levels

NASA Astrophysics Data System (ADS)

Morales-González, Merangeli; Vidot-Vega, Aidcer L.

2017-03-01

Performance-based seismic engineering is focused on the definition of limit states to represent different levels of damage, which can be described by material strains, drifts, displacements or even changes in dissipating properties and stiffness of the structure. This study presents a research plan to evaluate the behavior of reinforced concrete (RC) moment resistant frames at different performance levels established by the ASCE 41-06 seismic rehabilitation code. Sixteen RC plane moment frames with different span-to-depth ratios and three 3D RC frames were analyzed to evaluate their seismic behavior at different damage levels established by the ASCE 41-06. For each span-to-depth ratio, four different beam longitudinal reinforcement steel ratios were used that varied from 0.85 to 2.5% for the 2D frames. Nonlinear time history analyses of the frames were performed using scaled ground motions. The impact of different span-to-depth and reinforcement ratios on the damage levels was evaluated. Material strains, rotations and seismic hysteretic energy changes at different damage levels were studied.

Preparation and Reinforcement of Dual-Porous Biocompatible Cellulose Scaffolds for Tissue Engineering.

PubMed

Pircher, Nicole; Fischhuber, David; Carbajal, Leticia; Strauß, Christine; Nedelec, Jean-Marie; Kasper, Cornelia; Rosenau, Thomas; Liebner, Falk

2015-09-01

1Biocompatible cellulose-based aerogels composed of nanoporous struts, which embed interconnected voids of controlled micron-size, have been prepared employing temporary templates of fused porogens, reinforcement by interpenetrating PMMA networks and supercritical carbon dioxide drying. Different combinations of cellulose solvent (Ca(SCN) 2 /H 2 O/LiCl or [EMIm][OAc]/DMSO) and anti-solvent (EtOH), porogen type (paraffin wax or PMMA spheres) and porogen size (various fractions in the range of 100-500 μm) as well as intensity of PMMA reinforcement have been investigated to tailor the materials for cell scaffolding applications. All aerogels exhibited an open and dual porosity (micronporosity >100 μm and nanoporosity extending to the low micrometer range). Mechanical properties of the dual-porous aerogels under compressive stress were considerably improved by introduction of interpenetrating PMMA networks. The effect of the reinforcing polymer on attachment, spreading, and proliferation of NIH 3T3 fibroblast cells, cultivated on selected dual-porous aerogels to pre-evaluate their biocompatibility was similarly positive.

Inspection guide for column splice regions affected by premature concrete deterioration.

DOT National Transportation Integrated Search

2016-07-01

This guideline aims to help bridge inspectors and engineers in identifying and assessing the : capability of reinforced concrete column splice regions affected by varying degrees of premature : concrete deterioration due to alkali-silica reaction (AS...

Sustainability of transportation structures using composite materials to support trade and growth.

DOT National Transportation Integrated Search

2014-06-01

Corrosion-induced deterioration of steel rebar is one of the main reasons for repair and rehabilitation programs : for conventional steel-reinforced concrete bridge decks. According to the National Association of Corrosion Engineers : (NACE), of all ...

Macrophytes: ecosystem engineers in UK urban rivers

NASA Astrophysics Data System (ADS)

Gibbs, H.; Gurnell, A.; Heppell, K.; Spencer, K.

2012-04-01

Macrophytes act as ecosystem engineers within river channels in that they have the ability to cause geomorphological and ecological change. They induce reductions in flow velocity and associated sediment accumulation, and their system of underground roots and rhizomes also reinforces the accumulated sediment reducing sediment erosion and resuspension and creating habitats. As sediments, particularly finer-grained, store contaminants including metals, this engineering means that in the specific context of urban rivers where sediments are more likely to be contaminated, macrophytes trap and hold contaminated sediments creating a potentially important sink of metals. However, depending on the ability for the macrophyte to reinforce the sediment and reduce erosion and resuspension, there is the potential for the sink to turn in to a source and metals to be released in to the overlying water. This research therefore looks at the ecosystem engineering ability of common macrophytes in UK urban rivers by looking at: (i) the effect upon flow velocity and sediment accumulation of Sparganium erectum (branched bur-reed); (ii) the sediment reinforcement ability of both S. erectum, Typha latifolia (bulrush) and Phalaris arundinacea (reed canary grass); and, (iii) the storage of metals within the sediment, overlying water and the macrophytes. Research was undertaken on the River Blackwater, an urban river in Surrey, UK which has extensive macrophyte growth. Flow velocity measurements and fine sediment depths were recorded both within and outside of dense stands of S. erectum. The uprooting resistance (as an indicator of sediment reinforcement) was measured for three species: S. erectum, T. latifolia and P. arundinacea. Additionally, some preliminary sampling was undertaken of the sediment, overlying water and the macrophytes to determine metal storage. Lower flow velocities and greater volumes of fine sediment were recorded within the stands of S. erectum as opposed to the adjacent areas of open channel with minimal macrophyte growth. Uprooting resistances were considerable and differences were found both between species and over the annual growth cycle. T. latifolia showed the greatest uprooting resistance and P. arundinacea the lowest uprooting resistance. Maximum uprooting resistance for all species was in June. The sampled sediments were found to be a store of metals. For all macrophyte species, the below-ground tissues (roots and rhizomes) generally had greater metal concentrations than above-ground tissues (stem and leafs). The results from this research will help inform the use of macrophytes in the management of sediment-contaminated urban rivers.

Damage Precursor Investigation of Fiber-Reinforced Composite Materials Under Fatigue Loads

DTIC Science & Technology

2013-09-01

19.21, 215713. Thostenson, E. T.; Chou, T.‐W. Carbon Nanotube Networks: Sensing of Distributed Strain and Damage for Life Prediction and Self Healing ...composite structural life and the goal of the proposed research program to develop self -responsive engineered composites. Over 80%‒90% of the life of a...composite material. It is also envisaged to investigate and develop self -responsive engineered composite materials that provide an accurate health

Laser engineered net shaping of quasi-continuous network microstructural TiB reinforced titanium matrix bulk composites: Microstructure and wear performance

NASA Astrophysics Data System (ADS)

Hu, Yingbin; Ning, Fuda; Wang, Hui; Cong, Weilong; Zhao, Bo

2018-02-01

Titanium (Ti) and its alloys have been successfully applied to the aeronautical and biomedical industries. However, their poor tribological properties restrict their fields of applications under severe wear conditions. Facing to these challenges, this study investigated TiB reinforced Ti matrix composites (TiB-TMCs), fabricated by in-situ laser engineered net shaping (LENS) process, through analyzing parts quality, microstructure formation mechanisms, microstructure characterizations, and workpiece wear performance. At high B content areas (original B particle locations), reaction between Ti and B particles took place, generating flower-like microstructure. At low B content areas, eutectic TiB nanofibers contacted with each other with the formation of crosslinking microstructure. The crosslinking microstructural TiB aggregated and connected at the boundaries of Ti grains, forming a three-dimensional quasi-continuous network microstructure. The results show that compared with commercially pure Ti bulk parts, the TiB-TMCs exhibited superior wear performance (i.e. indentation wear resistance and friction wear resistance) due to the present of TiB reinforcement and the innovative microstructures formed inside TiB-TMCs. In addition, the qualities of the fabricated parts were improved with fewer interior defects by optimizing laser power, thus rendering better wear performance.

Anomaly detection of microstructural defects in continuous fiber reinforced composites

NASA Astrophysics Data System (ADS)

Bricker, Stephen; Simmons, J. P.; Przybyla, Craig; Hardie, Russell

2015-03-01

Ceramic matrix composites (CMC) with continuous fiber reinforcements have the potential to enable the next generation of high speed hypersonic vehicles and/or significant improvements in gas turbine engine performance due to their exhibited toughness when subjected to high mechanical loads at extreme temperatures (2200F+). Reinforced fiber composites (RFC) provide increased fracture toughness, crack growth resistance, and strength, though little is known about how stochastic variation and imperfections in the material effect material properties. In this work, tools are developed for quantifying anomalies within the microstructure at several scales. The detection and characterization of anomalous microstructure is a critical step in linking production techniques to properties, as well as in accurate material simulation and property prediction for the integrated computation materials engineering (ICME) of RFC based components. It is desired to find statistical outliers for any number of material characteristics such as fibers, fiber coatings, and pores. Here, fiber orientation, or `velocity', and `velocity' gradient are developed and examined for anomalous behavior. Categorizing anomalous behavior in the CMC is approached by multivariate Gaussian mixture modeling. A Gaussian mixture is employed to estimate the probability density function (PDF) of the features in question, and anomalies are classified by their likelihood of belonging to the statistical normal behavior for that feature.

Study on the measures of tunnels side-crossing bridge based on sheltering effects of isolation piles

NASA Astrophysics Data System (ADS)

Tang, Jian; Liu, Jun yan; Liu, Yan

2017-08-01

Based on the transit line 3, we studied the effect of the bridge piles crossed closely from the side by the shield tunnel. Using the three-dimensional finite element numerical analysis software Midas GTS/NX, we analyzed the effect of shield tunnel on pile deformation, statistics are obtained that under the condition of pile, subgrade reinforcement and ground changes. The calculation results show that in the condition of reinforcement, the new tunnel shield crossing through the pile caused longitudinal disturbance of the tunnel surrounding strata along the tunnel, where the soil over the area is within a certain range of pile and settlement deformation of surface subsidence occurs, changing the surface roughly to the shape of “V”. The maximum value appears above the shield tunnel and the value is high. In combination with engineering geology, hydrogeology and environment factors, this paper adopted isolation pile reinforcement to the pile, and the simulated results show that, pile settlement was significantly reduced under the condition of pile reinforcement. The calculation results show the rationality of the reinforcement scheme to a certain extent, which provides a theoretical basis for the similar tunnel.

Liquid Metal Infiltration Processing of Metallic Composites: A Critical Review

NASA Astrophysics Data System (ADS)

Sree Manu, K. M.; Ajay Raag, L.; Rajan, T. P. D.; Gupta, Manoj; Pai, B. C.

2016-10-01

Metal matrix composites (MMC) are one of the advanced materials widely used for aerospace, automotive, defense, and general engineering applications. MMC can be tailored to have superior properties such as enhanced high-temperature performance, high specific strength and stiffness, increased wear resistance, better thermal and mechanical fatigue, and creep resistance than those of unreinforced alloys. To fabricate such composites with ideal properties, the processing technique has to ensure high volume fraction of reinforcement incorporation, uniform distribution of the reinforcement, and acceptable adhesion between the matrix and the reinforcing phase without unwanted interfacial reactions which degrades the mechanical properties. A number of processing techniques such as stir casting/vortex method, powder metallurgy, infiltration, casting etc. have been developed to synthesize MMC employing a variety of alloy and the reinforcement's combinations. Among these, infiltration process is widely used for making MMC with high volume fraction of reinforcements and offers many more advantages compared to other conventional manufacturing processes. The present paper critically reviews the various infiltration techniques used for making the MMC, their process parameters, characteristics, and selected studies carried out worldwide and by authors on the development of metal ceramic composites by squeeze infiltration process.

Performance of geogrid reinforced ballast under dynamic loading.

DOT National Transportation Integrated Search

2012-07-01

Railroad ballast consists of open graded crushed stone used as a bed for railroad track to provide stability. Over time, : ballast degrades and loses its strength. Fouling of ballast with fines has been a major issue of railway engineering. In this :...

The effect of load history on reinforced concrete bridge column behavior : [summary].

DOT National Transportation Integrated Search

2012-08-01

To satisfy the aims of performance based design, levels of damage which interrupt the serviceability of the : structure or require more invasive repair techniques must be related to engineering criteria. In this report, the : influence of displacemen...

The effect of load history on reinforced concrete bridge column behavior.

DOT National Transportation Integrated Search

2012-08-01

To satisfy the aims of performance based design, levels of damage which interrupt the serviceability of the : structure or require more invasive repair techniques must be related to engineering criteria. In this report, the : influence of displacemen...

Health monitoring of reinforced concrete structures based on PZT admittance signal

NASA Astrophysics Data System (ADS)

Wang, Dansheng; Zhu, Hongping; Shen, Danyan; Ge, Dongdong

2009-07-01

Reinforced concrete (RC) structure is one of most familiar engineering structure styles in the civil engineering community, which often suffer crack damage during their service life because of some factors such as overloading, excessive use, and bad environmental conditions. Thus early detection of crack damage is of special concern for RC structures. Piezoelectric materials have direct and converse piezoelectric effects and can serve as actuators or sensors. A health monitoring method based on PZT admittance signals is addressed in this paper, which use the electromechanical coupling property of piezoelectric materials. An experimental study on health monitoring of a RC beam is implemented based on the PZT admittance signals. In this experiment, the electrical admittances of distributed PZT sheets are measured when the host beams are suffering from variable loads. From the obtained PZT admittance curves one can find that the presence of incipient crack can be captured and the cracking load of the RC beam can also generally determined. By the experimental study it is concluded that the health monitoring technique is quite effective and sensitive for RC structures, which indicates its favorable application foreground in civil engineering field.

Low Frequency Electrical and Magnetic Methods for Non-Destructive Analysis of Fiber Dispersion in Fiber Reinforced Cementitious Composites: An Overview

PubMed Central

Faifer, Marco; Ferrara, Liberato; Ottoboni, Roberto; Toscani, Sergio

2013-01-01

Non-destructive analysis of fiber dispersion in structural elements made of Fiber Reinforced Concrete (FRC) and Fiber Reinforced Cementitious Composites (FRCCs) plays a significant role in the framework of quality control and performance prediction. In this paper, the research activity of the authors in the aforementioned field all over the last lustrum will be reviewed. A method based on the measurement of the inductance of a probe to be placed on the specimen will be presented and its progressive development will be described. Obtained correlation with actual fiber dispersion, as checked by means of destructive methods, as well as with the mechanical performance of the composite will also be presented, in an attempt to address the significance of the method from an engineering application perspective. PMID:23337334

A Study on 3-Body Abrasive Wear Behaviour of Aluminium 8011 / Graphite Metal Matrix Composite

NASA Astrophysics Data System (ADS)

Latha Shankar, B.; Anil, K. C.; Patil, Rahul

2016-09-01

Metals and alloys have found their vital role in many applications like structural, corrosive, tribological, etc., in engineering environment. The alloys/composites having high strength to low weight ratio have gained attention of many researchers recently. In this work, graphite reinforced Aluminium 8011 metal matrix composite was prepared by conventional stir casting route, by varying the weight % of reinforcement. Uniform distribution of Graphite in matrix alloy was confirmed by optical micrographs. Prepared composite specimens were subjected to 3-body abrasive testing by varying applied load and time, the silica particles of 400 grit size were used as abrasive particles. It was observed that with the increase of weight% of Graphite the wear resistance of composite was also increasing and on comparison it was found that reinforced composite gives good wear resistance than base alloy.

Mathematical modeling of the stress-strain state of the outlet guide vane made of various materials

NASA Astrophysics Data System (ADS)

Grinev, M. A.; Anoshkin, A. N.; Pisarev, P. V.; Zuiko, V. Yu.; Shipunov, G. S.

2016-11-01

The present work is devoted to the detailed stress-strain analysis of the composite outlet guide vane (OGV) for aircraft engines with a special focus on areas with twisted layers where the initiation of high interlaminar stresses is most expected. Various polymer composite materials and reinforcing schemes are researched. The technological scheme of laying-out of anisotropic plies and the fastening method are taken into account in the model. The numerical simulation is carried out by the finite element method (FEM) with the ANSYS Workbench software. It is shown that interlaminar shear stresses are most dangerous. It is found that balanced carbon fiber reinforced plastic (CFRP) with the [0°/±45°] reinforcing scheme allows us to provide the double strength margin under working loads for the developed OGV.

Low frequency electrical and magnetic methods for non-destructive analysis of fiber dispersion in fiber reinforced cementitious composites: an overview.

PubMed

Faifer, Marco; Ferrara, Liberato; Ottoboni, Roberto; Toscani, Sergio

2013-01-21

Non-destructive analysis of fiber dispersion in structural elements made of Fiber Reinforced Concrete (FRC) and Fiber Reinforced Cementitious Composites (FRCCs) plays a significant role in the framework of quality control and performance prediction. In this paper, the research activity of the authors in the aforementioned field all over the last lustrum will be reviewed. A method based on the measurement of the inductance of a probe to be placed on the specimen will be presented and its progressive development will be described. Obtained correlation with actual fiber dispersion, as checked by means of destructive methods, as well as with the mechanical performance of the composite will also be presented, in an attempt to address the significance of the method from an engineering application perspective.

Flow Navigation by Smart Microswimmers via Reinforcement Learning

NASA Astrophysics Data System (ADS)

Colabrese, Simona; Biferale, Luca; Celani, Antonio; Gustavsson, Kristian

2017-11-01

We have numerically modeled active particles which are able to acquire some limited knowledge of the fluid environment from simple mechanical cues and exert a control on their preferred steering direction. We show that those swimmers can learn effective strategies just by experience, using a reinforcement learning algorithm. As an example, we focus on smart gravitactic swimmers. These are active particles whose task is to reach the highest altitude within some time horizon, exploiting the underlying flow whenever possible. The reinforcement learning algorithm allows particles to learn effective strategies even in difficult situations when, in the absence of control, they would end up being trapped by flow structures. These strategies are highly nontrivial and cannot be easily guessed in advance. This work paves the way towards the engineering of smart microswimmers that solve difficult navigation problems. ERC AdG NewTURB 339032.

Challenges in the Verification of Reinforcement Learning Algorithms

NASA Technical Reports Server (NTRS)

Van Wesel, Perry; Goodloe, Alwyn E.

2017-01-01

Machine learning (ML) is increasingly being applied to a wide array of domains from search engines to autonomous vehicles. These algorithms, however, are notoriously complex and hard to verify. This work looks at the assumptions underlying machine learning algorithms as well as some of the challenges in trying to verify ML algorithms. Furthermore, we focus on the specific challenges of verifying reinforcement learning algorithms. These are highlighted using a specific example. Ultimately, we do not offer a solution to the complex problem of ML verification, but point out possible approaches for verification and interesting research opportunities.

Functionally graded bio-ceramic reinforced PVA hydrogel composites for knee joint artificial cartilages

NASA Astrophysics Data System (ADS)

Kumar, G. C. Mohan

2018-04-01

Research progress in materials science for bio-based materials for cartilage repair or supportive to host tissue has become a fashionable, worldwide. Few efforts in biomedical engineering has attempted in the development of newer biomaterials successfully. Bio ceramics, a class of materials been used in particulate form as a reinforcement with polymers those ensure its biocompatibility. Every artificial biomedical system has to meet the minimum in Vitro requirements for successful application. Equally the biological behavior of normal and diseased tissues is also essential to understand the artificial systems to human body.

A Stress Analysis of Circular Cylindrical Shell Intersections, Including the Influences of Reinforcement, Cyclic Plasticity and Fatigue.

DTIC Science & Technology

1980-12-01

Professor Paul M. Naghdi National Academy of Sciences University of California National Research Council Department of Mechanical Engineering Ship Hull...Angeles, California 90024 Department of Mechanical Engineering Washington, D.C. 20064 Professor Burt Paul University of Pennsylvania Dr. Samuel B...78u4 74 -6 19 Universities (Con’t) Universities (Con’t) Dr. V. K. Varadan Professor V. H. Neubert Ohio State University Research Foundation Pennsylvania

8. EXTERIOR VIEW OF BALTIMORE FAN HOUSE LOOKING NORTHEAST The ...

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

8. EXTERIOR VIEW OF BALTIMORE FAN HOUSE LOOKING NORTHEAST The engine room and south airway are in the foreground. The brick walls covering the fan housing and brick upshaft chimney are in the background. The engine room, fan housing, and airways are covered with reinforced concrete roofing. In the left foreground is an airlock leading into the airway. - Dorrance Colliery Fan Complex, South side of Susquehanna River at Route 115 & Riechard Street, Wilkes-Barre, Luzerne County, PA

Ceramic Parts for Turbines

NASA Technical Reports Server (NTRS)

Jones, R. D.; Carpenter, Harry W.; Tellier, Jim; Rollins, Clark; Stormo, Jerry

1987-01-01

Abilities of ceramics to serve as turbine blades, stator vanes, and other elements in hot-gas flow of rocket engines discussed in report. Ceramics prime candidates, because of resistance to heat, low density, and tolerance of hostile environments. Ceramics considered in report are silicon nitride, silicon carbide, and new generation of such ceramic composites as transformation-toughened zirconia and alumina and particulate- or whisker-reinforced matrices. Report predicts properly designed ceramic components viable in advanced high-temperature rocket engines and recommends future work.

High Temperature Chemistry at NASA: Hot Topics

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.

2014-01-01

High Temperature issues in aircraft engines Hot section: Ni and Co based Superalloys Oxidation and Corrosion (Durability) at high temperatures. Thermal protection system (TPS) and RCC (Reinforced Carbon-Carbon) on the Space Shuttle Orbiter. High temperatures in other worlds: Planets close to their stars.

Repairing/strengthening of bridges with post-tensioned FRP strands and performance evaluation.

DOT National Transportation Integrated Search

2008-06-01

The proposed project is to take advantage of some new developments in bridge engineering to apply fiber reinforced polymers (FRP) post-tensioning strands on a selected structure. The use of externally post-tensioned FRP strands to repair/strengthen b...

Revolution in airplane construction? Grob G110: The first modern fiber glass composition airplane shortly before its maiden flight

NASA Technical Reports Server (NTRS)

Dorpinghaus, R.

1982-01-01

A single engine two passenger airplane, constructed completely from fiber reinforced plastic materials is introduced. The cockpit, controls, wing profile, and landing gear are discussed. Development of the airframe is also presented.

Estimating the residual axial load capacity of flexure-dominated reinforced concrete bridge columns.

DOT National Transportation Integrated Search

2014-08-01

Extreme events such as earthquakes have the potential to damage hundreds, if not thousands, of bridges on a : transportation network. Following an earthquake, the damaged bridges are inspected by engineers sequentially to : decide whether or not to c...

All-round joining method with carbon fiber reinforced interface

NASA Astrophysics Data System (ADS)

Miwa, Noriyoshi; Tanaka, Kazunori; Kamiya, Yoshiko; Nishi, Yoshitake

2008-08-01

Carbon fiber reinforced polymer (CFRP) has been recently applied to not only wing, but also fan blades of turbo fan engines. To prevent impact force, leading edge of titanium was often mounted on the CFRP fan blades with adhesive force. In order to enhance the joining strength, a joining method with carbon fiber reinforced interface has been developed. By using nickel-coated carbon fibers, a joining sample with carbon fiber-reinforced interface between CFRP and CFRM has been successfully developed. The joining sample with nickel-coated carbon fiber interface exhibits the high tensile strength, which was about 10 times higher than that with conventional adhesion. On the other hand, Al-welding methods to steel, Cu and Ti with carbon fiber reinforced interface have been successfully developed to lighten the parts of machines of racing car and airplane. Carbon fibers in felt are covered with metals to protect the interfacial reaction. The first step of the welding method is that the Al coated felt is contacted and wrapped with molten aluminum solidified under gravity pressure, whereas the second step is that the felt with double layer of Ni and Al is contacted and wrapped with molten steel (Cu or Ti) solidified under gravity pressure. Tensile strength of Al-Fe (Cu or Ti) welded sample with carbon fiber reinforced interface is higher than those of Al-Fe (Cu or Ti) welded sample.

Advanced rocket propulsion

NASA Technical Reports Server (NTRS)

Obrien, Charles J.

1993-01-01

Existing NASA research contracts are supporting development of advanced reinforced polymer and metal matrix composites for use in liquid rocket engines of the future. Advanced rocket propulsion concepts, such as modular platelet engines, dual-fuel dual-expander engines, and variable mixture ratio engines, require advanced materials and structures to reduce overall vehicle weight as well as address specific propulsion system problems related to elevated operating temperatures, new engine components, and unique operating processes. High performance propulsion systems with improved manufacturability and maintainability are needed for single stage to orbit vehicles and other high performance mission applications. One way to satisfy these needs is to develop a small engine which can be clustered in modules to provide required levels of total thrust. This approach should reduce development schedule and cost requirements by lowering hardware lead times and permitting the use of existing test facilities. Modular engines should also reduce operational costs associated with maintenance and parts inventories.

ISSLS prize winner: integrating theoretical and experimental methods for functional tissue engineering of the annulus fibrosus.

PubMed

Nerurkar, Nandan L; Mauck, Robert L; Elliott, Dawn M

2008-12-01

Integrating theoretical and experimental approaches for annulus fibrosus (AF) functional tissue engineering. Apply a hyperelastic constitutive model to characterize the evolution of engineered AF via scalar model parameters. Validate the model and predict the response of engineered constructs to physiologic loading scenarios. There is need for a tissue engineered replacement for degenerate AF. When evaluating engineered replacements for load-bearing tissues, it is necessary to evaluate mechanical function with respect to the native tissue, including nonlinearity and anisotropy. Aligned nanofibrous poly-epsilon-caprolactone scaffolds with prescribed fiber angles were seeded with bovine AF cells and analyzed over 8 weeks, using experimental (mechanical testing, biochemistry, histology) and theoretical methods (a hyperelastic fiber-reinforced constitutive model). The linear region modulus for phi = 0 degrees constructs increased by approximately 25 MPa, and for phi = 90 degrees by approximately 2 MPa from 1 day to 8 weeks in culture. Infiltration and proliferation of AF cells into the scaffold and abundant deposition of s-GAG and aligned collagen was observed. The constitutive model had excellent fits to experimental data to yield matrix and fiber parameters that increased with time in culture. Correlations were observed between biochemical measures and model parameters. The model was successfully validated and used to simulate time-varying responses of engineered AF under shear and biaxial loading. AF cells seeded on nanofibrous scaffolds elaborated an organized, anisotropic AF-like extracellular matrix, resulting in improved mechanical properties. A hyperelastic fiber-reinforced constitutive model characterized the functional evolution of engineered AF constructs, and was used to simulate physiologically relevant loading configurations. Model predictions demonstrated that fibers resist shear even when the shearing direction does not coincide with the fiber direction. Further, the model suggested that the native AF fiber architecture is uniquely designed to support shear stresses encountered under multiple loading configurations.

Use of fiber reinforced concrete for concrete pavement slab replacement : [summary].

DOT National Transportation Integrated Search

2014-03-01

Replacing cracked concrete in roadways requires : lanes to be closed and traff c disrupted. One way : to reduce road closure time is to reduce concrete : curing time. To accelerate curing time, pavement : engineers mix a very low water-cement ratio w...

Featherweight Challenge

ERIC Educational Resources Information Center

Love, Tyler S.; Ryan, Larry

2012-01-01

As science, technology education, and engineering programs suffer budget cuts, educators continue to seek cost-effective activities that engage students and reinforce standards. The featherweight challenge is a hands-on activity that challenges students to continually refine their design while not breaking the budget. This activity uses one of the…

Compatibility of potential reinforcing ceramics with Ni and Fe aluminides

NASA Technical Reports Server (NTRS)

Clark, William A. T.; Moser, Jeffrey A.

1991-01-01

There is a great deal of interest in the possible utilization of intermetallic compounds in advanced high temperature gas turbine engines. These compounds exhibit a variety of promising properties, including reasonable strength, high melting points, relatively low densities, and good corrosion resistance. However, in general, they also show limited ductilities and toughness, and less than optimum creep strengths at elevated temperatures. In addition, in applications involving advanced gas turbine engines, it is often necessary for candidate materials to have large elastic moduli. The present study is part of a program whose objective is to identify a high temperature fiber reinforced composite. The approach adopted was to fabricate laboratory samples of the combinations of materials considered by Misra, in order to determine the extent to which the thermodynamic calculations can predict phase stability. As many of the ceramic phases considered are not currently available in fiber form, they were added as particulates to the alloy matrices. The ways in which the materials were produced and evaluated are described.

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (hands extended) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

NASA Image and Video Library

2003-09-26

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (hands extended) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (facing camera) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

NASA Image and Video Library

2003-09-26

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (facing camera) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (left) talks to a phalanx of media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

NASA Image and Video Library

2003-09-26

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (left) talks to a phalanx of media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (right) talks to the media in the Orbiter Processing Facility . The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

NASA Image and Video Library

2003-09-26

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (right) talks to the media in the Orbiter Processing Facility . The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

KENNEDY SPACE CENTER, FLA. - The media gather around NASA Vehicle Manager Scott Thurston (white shirt, right) who talks about some of the work being done on the orbiter Atlantis as it is being prepared for Return to Flight in the Orbiter Processing Facility. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

NASA Image and Video Library

2003-09-26

KENNEDY SPACE CENTER, FLA. - The media gather around NASA Vehicle Manager Scott Thurston (white shirt, right) who talks about some of the work being done on the orbiter Atlantis as it is being prepared for Return to Flight in the Orbiter Processing Facility. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

Cyclic hot firing results of tungsten-wire-reinforced, copper-lined thrust chambers

NASA Technical Reports Server (NTRS)

Kazaroff, John M.; Jankovsky, Robert S.

1990-01-01

An advanced thrust liner material for potential long life reusable rocket engines is described. This liner material was produced with the intent of improving the reusable life of high pressure thrust chambers by strengthening the chamber in the hoop direction, thus avoiding the longitudinal cracking due to low cycle fatigue that is observed in conventional homogeneous copper chambers, but yet not reducing the high thermal conductivity that is essential when operating with high heat fluxes. The liner material produced was a tungsten wire reinforced copper composite. Incorporating this composite into two hydrogen-oxygen test rocket chambers was done so that its performance as a reusable liner material could be evaluated. Testing results showed that both chambers failed prematurely, but the crack sites were perpendicular to the normal direction of cracking indicating a degree of success in containing the tremendous thermal strain associated with high temperature rocket engines. The failures, in all cases, were associated with drilled instrumentation ports and no other damages or deformations were found elsewhere in the composite liners.

Development and application of new composite grouting material for sealing groundwater inflow and reinforcing wall rock in deep mine.

PubMed

Jinpeng, Zhang; Limin, Liu; Futao, Zhang; Junzhi, Cao

2018-04-04

With cement, bentonite, water glass, J85 accelerator, retarder and water as raw materials, a new composite grouting material used to seal groundwater inflow and reinforce wall rock in deep fractured rock mass was developed in this paper. Based on the reaction mechanism of raw material, the pumpable time, stone rate, initial setting time, plastic strength and unconfined compressive strength of multi-group proportion grouts were tested by orthogonal experiment. Then, the optimum proportion of composite grouting material was selected and applied to the grouting engineering for sealing groundwater inflow and reinforcing wall rock in mine shaft lining. The results show the mixing proportion of the maximum pumpable time, maximum stone rate and minimum initial setting time of grout are A K4 B K1 C K4 D K2 , A K3 B K1 C K1 D K4 and A K3 B K3 C K4 D K1 , respectively. The mixing proportion of the maximum plastic strength and unconfined compressive strength of grouts concretion bodies are A K1 B K1 C K1 D K3 and A K1 B K1 C K1 D K1 , respectively. Balanced the above 5 indicators overall and determined the optimum proportion of grouts: bentonite-cement ratio of 1.0, water-solid ratio of 3.5, accelerator content of 2.9% and retarder content of 1.45%. This new composite grouting material had good effect on the grouting engineering for sealing groundwater inflow and reinforcing wall rock in deep fractured rock mass.

Fatigue and post-fatigue performance of Fabry-Perot FOS installed on CFRP-strengthened RC-beams

NASA Astrophysics Data System (ADS)

Gheorghiu, Catalin; Labossiere, Pierre; Proulx, Jean

2004-07-01

There is a growing need for built-in monitoring systems for civil engineering infrastructures, due to problems such as increasing traffic loads and rising costs of maintenance and repair. Fibre optic sensors (FOS), capable of reading various parameters are promising candidates for life-long health monitoring of these structures. However, since FOS have only been introduced recently into the field of structural monitoring, their acceptance and widespread implementation will be conditioned by their durability under severe climatic and loading conditions. This paper reports on the performance of strain extrinsic FOS attached to carbon fibre reinforced polymer (CFRP) plates used to strengthen concrete structures. The specimens tested in this project are reinforced concrete (RC) beams with an additional external CFRP reinforcement. The FOS-instrumented beams were first subjected to fatigue loading for various numbers of cycles and load amplitudes. Then, they were tested monotonically to failure under four-point-bending. The test results provide an insight on the fatigue and post-fatigue behaviour of FOS used for monitoring reinforced concrete structures.

Self-healing in single and multiple fiber(s) reinforced polymer composites

NASA Astrophysics Data System (ADS)

Woldesenbet, E.

2010-06-01

You Polymer composites have been attractive medium to introduce the autonomic healing concept into modern day engineering materials. To date, there has been significant research in self-healing polymeric materials including several studies specifically in fiber reinforced polymers. Even though several methods have been suggested in autonomic healing materials, the concept of repair by bleeding of enclosed functional agents has garnered wide attention by the scientific community. A self-healing fiber reinforced polymer composite has been developed. Tensile tests are carried out on specimens that are fabricated by using the following components: hollow and solid glass fibers, healing agent, catalysts, multi-walled carbon nanotubes, and a polymer resin matrix. The test results have demonstrated that single fiber polymer composites and multiple fiber reinforced polymer matrix composites with healing agents and catalysts have provided 90.7% and 76.55% restoration of the original tensile strength, respectively. Incorporation of functionalized multi-walled carbon nanotubes in the healing medium of the single fiber polymer composite has provided additional efficiency. Healing is found to be localized, allowing multiple healing in the presence of several cracks.

A Monitoring Method Based on FBG for Concrete Corrosion Cracking

PubMed Central

Mao, Jianghong; Xu, Fangyuan; Gao, Qian; Liu, Shenglin; Jin, Weiliang; Xu, Yidong

2016-01-01

Corrosion cracking of reinforced concrete caused by chloride salt is one of the main determinants of structure durability. Monitoring the entire process of concrete corrosion cracking is critical for assessing the remaining life of the structure and determining if maintenance is needed. Fiber Bragg Grating (FBG) sensing technology is extensively developed in photoelectric monitoring technology and has been used on many projects. FBG can detect the quasi-distribution of strain and temperature under corrosive environments, and thus it is suitable for monitoring reinforced concrete cracking. According to the mechanical principle that corrosion expansion is responsible for the reinforced concrete cracking, a package design of reinforced concrete cracking sensors based on FBG was proposed and investigated in this study. The corresponding relationship between the grating wavelength and strain was calibrated by an equal strength beam test. The effectiveness of the proposed method was verified by an electrically accelerated corrosion experiment. The fiber grating sensing technology was able to track the corrosion expansion and corrosion cracking in real time and provided data to inform decision-making for the maintenance and management of the engineering structure. PMID:27428972

A Monitoring Method Based on FBG for Concrete Corrosion Cracking.

PubMed

Mao, Jianghong; Xu, Fangyuan; Gao, Qian; Liu, Shenglin; Jin, Weiliang; Xu, Yidong

2016-07-14

Corrosion cracking of reinforced concrete caused by chloride salt is one of the main determinants of structure durability. Monitoring the entire process of concrete corrosion cracking is critical for assessing the remaining life of the structure and determining if maintenance is needed. Fiber Bragg Grating (FBG) sensing technology is extensively developed in photoelectric monitoring technology and has been used on many projects. FBG can detect the quasi-distribution of strain and temperature under corrosive environments, and thus it is suitable for monitoring reinforced concrete cracking. According to the mechanical principle that corrosion expansion is responsible for the reinforced concrete cracking, a package design of reinforced concrete cracking sensors based on FBG was proposed and investigated in this study. The corresponding relationship between the grating wavelength and strain was calibrated by an equal strength beam test. The effectiveness of the proposed method was verified by an electrically accelerated corrosion experiment. The fiber grating sensing technology was able to track the corrosion expansion and corrosion cracking in real time and provided data to inform decision-making for the maintenance and management of the engineering structure.

An Experimental Evaluation of Mechanical Properties of Hybrid Reinforcements

NASA Astrophysics Data System (ADS)

Sai Kumar, A.; Ganesan, G.; Karthikeyan, K.

2017-07-01

This paper presents the mechanical properties of unidirectional hybrid reinforcements formed from continuous fibres impregnated with a fibre binding material which are used for reinforcing the concrete. Recently FRP (Fibre Reinforced Polymer) manufacturers and suppliers have been increased all over the world because of the superior performance of FRP products in the construction industry. Its non-corrosive nature has turned the attention of many researchers to make several studies on different type of FRP products. Through a vast research, several standards also have been formulated. In this regard a new combination of FRP materials is tried in this paper and its properties have been derived. Carbon fibre and glass fibres fuse in this study to form a new hybrid rebar. The design properties such as tensile strength, tensile modulus, and compressive strength have been studied as per ASTM standards and it has been identified that the Hybrid rebar show a superior performance in comparison with GFRP (Glass FRP) and Steel rebars. This extraordinary performance of hybrid composite material increases the extensive engineering applications such as transport industry, aeronautics, naval, automotive industries.

Preparation and Reinforcement of Dual‐Porous Biocompatible Cellulose Scaffolds for Tissue Engineering

PubMed Central

Pircher, Nicole; Fischhuber, David; Carbajal, Leticia; Strauß, Christine; Nedelec, Jean‐Marie; Kasper, Cornelia; Rosenau, Thomas

2015-01-01

1 Biocompatible cellulose‐based aerogels composed of nanoporous struts, which embed interconnected voids of controlled micron‐size, have been prepared employing temporary templates of fused porogens, reinforcement by interpenetrating PMMA networks and supercritical carbon dioxide drying. Different combinations of cellulose solvent (Ca(SCN)2/H2O/LiCl or [EMIm][OAc]/DMSO) and anti‐solvent (EtOH), porogen type (paraffin wax or PMMA spheres) and porogen size (various fractions in the range of 100–500 μm) as well as intensity of PMMA reinforcement have been investigated to tailor the materials for cell scaffolding applications. All aerogels exhibited an open and dual porosity (micronporosity >100 μm and nanoporosity extending to the low micrometer range). Mechanical properties of the dual‐porous aerogels under compressive stress were considerably improved by introduction of interpenetrating PMMA networks. The effect of the reinforcing polymer on attachment, spreading, and proliferation of NIH 3T3 fibroblast cells, cultivated on selected dual‐porous aerogels to pre‐evaluate their biocompatibility was similarly positive. PMID:26941565

Airfield construction (3rd revised and enlarged edition)

NASA Astrophysics Data System (ADS)

Goretskii, Leonid I.; Boguslavskii, Adol'f. M.; Serebrenikov, Vadim A.; Barzdo, V. I.; Leshchitskaia, T. P.; Polosin-Nikitin, S. M.

The principal engineering aspects of airfield construction are discussed. In particular, attention is given to the fundamental principles and organizational aspects of airfield construction; excavation work and airfield layout; construction of drainage systems; foundations and pavements; and quality control and safety engineering. The discussion also covers the operation of various support plants, including concrete production and mixing, production of asphalt-concrete mixtures and organic binders, production of structural steel and reinforced concrete components, and operation of stone quarries and gravel pits.

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

PubMed

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

2016-07-01

Ceramic/polymer composite equipped with 3D interlocking skeleton (3D IL) is developed through a simple freeze-casting method, exhibiting exceptionally light weight, high strength, toughness, and shock resistance. Long-range crack energy dissipation enabled by 3D interlocking structure is considered as the primary reinforcing mechanism for such superior properties. The smart composite design strategy should hold a place in developing future structural engineering materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hot Extrusion of A356 Aluminum Metal Matrix Composite with Carbon Nanotube/Al2O3 Hybrid Reinforcement

NASA Astrophysics Data System (ADS)

Kim, H. H.; Babu, J. S. S.; Kang, C. G.

2014-05-01

Over the years, the attention of material scientists and engineers has shifted from conventional composite materials to nanocomposite materials for the development of light weight and high-performance devices. Since the discovery of carbon nanotubes (CNTs), many researchers have tried to fabricate metal matrix composites (MMCs) with CNT reinforcements. However, CNTs exhibit low dispersibility in metal melts owing to their poor wettability and large surface-to-volume ratio. The use of an array of short fibers or hybrid reinforcements in a preform could overcome this problem and enhance the dispersion of CNTs in the matrix. In this study, multi-walled CNT/Al2O3 preform-based aluminum hybrid composites were fabricated using the infiltration method. Then, the composites were extruded to evaluate changes in its mechanical properties. In addition, the dispersion of reinforcements was investigated using a hardness test. The required extrusion pressure of hybrid MMCs increased as the Al2O3/CNT fraction increased. The deformation resistance of hybrid material was over two times that of the original A356 aluminum alloy material due to strengthening by the Al2O3/CNTs reinforcements. In addition, an unusual trend was detected; primary transition was induced by the hybrid reinforcements, as can be observed in the pressure-displacement curve. Increasing temperature of the material can help increase formability. In particular, temperatures under 623 K (350 °C) and over-incorporating reinforcements (Al2O3 20 pct, CNTs 3 pct) are not recommended owing to a significant increase in the brittleness of the hybrid material.

A new type of smart basalt fiber-reinforced polymer bars as both reinforcements and sensors for civil engineering application

NASA Astrophysics Data System (ADS)

Tang, Yongsheng; Wu, Zhishen; Yang, Caiqian; Wu, Gang; Shen, Sheng

2010-11-01

In this paper, a new type of smart basalt fiber-reinforced polymer (BFRP) bar is developed and their sensing performance is investigated by using the Brillouin scattering-based distributed fiber optic sensing technique. The industrial manufacturing process is first addressed, followed by an experimental study on the strain, temperature and fundamental mechanical properties of the BFRP bars. The results confirm the superior sensing properties, in particular the measuring accuracy, repeatability and linearity through comparing with bare optical fibers. Results on the mechanical properties show stable elastic modulus and high ultimate strength. Therefore, the smart BFRP bar has potential applications for long-term structural health monitoring (SHM) as embedded sensors as well as strengthening and upgrading structures. Moreover the coefficient of thermal expansion for smart BFRP bars is similar to the value for concrete.

Two-dimensional magnesium oxide nanosheets reinforced epoxy nanocomposites for enhanced fracture toughness

NASA Astrophysics Data System (ADS)

Balguri, Praveen Kumar; Harris Samuel, D. G.; Guruvishnu, T.; Aditya, D. B.; Mahadevan, S. M.; Thumu, Udayabhaskararao

2018-01-01

Metal oxide nanoparticles have been used as excellent reinforcements to enhance mechanical properties of polymers, natural composites, and ceramics. To date, a major portion of metal oxides used as nanofillers is three dimensional spherical nanoparticles. In the last decade, two-dimensional (2D) materials such as graphene have been widely investigated to improve the mechanical and electrical properties of polymer materials. In this paper, 2D Magnesium oxide (MgO) nanosheets reinforced epoxy composites (0.1, 0.2 and 0.4 wt%) are fabricated and studied for their ability to resist the propagation of preexisting flaw by conducting fracture toughness test for K IC, critical stress intensity factor. This property is an important mechanical property for designing applications in various engineering technologies. Our results show that the MgO with 0.2 wt% is the optimized level to improve the fracture toughness of the epoxy polymer by 47%.

Dependence of equivalent thermal conductivity coefficients of single-wall carbon nanotubes on their chirality

NASA Astrophysics Data System (ADS)

Zarubin, V. S.; Sergeeva, E. S.

2018-04-01

Composite materials (composites) composed of a matrix and reinforcing components are currently widely used as structural materials for various engineering devices designed to operate under extreme thermal and mechanical loads. By modifying a composite with structure-sensitive inclusions such as single-wall carbon nanotubes, one can significantly improve the thermomechanical properties of the resulting material. The paper presents relationships obtained for the equivalent thermal conductivity coefficients of single-wall carbon nanotubes versus their chirality using a simulation model developed to simulate the heat transfer process through thermal conductivity in a transversely isotropic environment. With these coefficients, one can conventionally substitute a single-wall carbon nanotube with a continuous anisotropic fiber, thus allowing one to estimate the thermal properties of composites reinforced with objects of this sort by using the well-known models developed for fibered composites. The results presented here can be used to estimate the thermal properties of carbon nanotube-reinforced composites.

Quantifying Uncertainties in the Thermo-Mechanical Properties of Particulate Reinforced Composites

NASA Technical Reports Server (NTRS)

Mital, Subodh K.; Murthy, Pappu L. N.

1999-01-01

The present paper reports results from a computational simulation of probabilistic particulate reinforced composite behavior. The approach consists use of simplified micromechanics of particulate reinforced composites together with a Fast Probability Integration (FPI) technique. Sample results are presented for a Al/SiC(sub p)(silicon carbide particles in aluminum matrix) composite. The probability density functions for composite moduli, thermal expansion coefficient and thermal conductivities along with their sensitivity factors are computed. The effect of different assumed distributions and the effect of reducing scatter in constituent properties on the thermal expansion coefficient are also evaluated. The variations in the constituent properties that directly effect these composite properties are accounted for by assumed probabilistic distributions. The results show that the present technique provides valuable information about the scatter in composite properties and sensitivity factors, which are useful to test or design engineers.

Hierarchical, multilayered cell walls reinforced by recycled silk cocoons enhance the structural integrity of honeybee combs

PubMed Central

Zhang, Kai; Duan, Huiling; Karihaloo, Bhushan L.; Wang, Jianxiang

2010-01-01

We reveal the sophisticated and hierarchical structure of honeybee combs and measure the elastic properties of fresh and old natural honeycombs at different scales by optical microscope, environmental scanning electron microscope, nano/microindentation, and by tension and shear tests. We demonstrate that the comb walls are continuously strengthened and stiffened without becoming fragile by the addition of thin wax layers reinforced by recycled silk cocoons reminiscent of modern fiber-reinforced composite laminates. This is done to increase its margin of safety against collapse due to a temperature increase. Artificial engineering honeycombs mimic only the macroscopic geometry of natural honeycombs, but have yet to achieve the microstructural sophistication of their natural counterparts. The natural honeycombs serve as a prototype of truly biomimetic cellular materials with hitherto unattainable improvement in stiffness, strength, toughness, and thermal stability. PMID:20439765

AC and DC electrical properties of graphene nanoplatelets reinforced epoxy syntactic foam

NASA Astrophysics Data System (ADS)

Zegeye, Ephraim; Wicker, Scott; Woldesenbet, Eyassu

2018-04-01

Benefits of employing graphene nanopletlates (GNPLs) in composite structures include mechanical as well as multifunctional properties. Understanding the impedance behavior of GNPLs reinforced syntactic foams may open new applications for syntactic foam composites. In this work, GNPLs reinforced syntactic foams were fabricated and tested for DC and AC electrical properties. Four sets of syntactic foam samples containing 0, 0.1, 0.3, and 0.5 vol% of GNPLs were fabricated and tested. Significant increase in conductivity of syntactic foams due to the addition of GNPLs was noted. AC impedance measurements indicated that the GNPLs syntactic foams become frequency dependent as the volume fraction of GNPLs increases. With addition of GNPLs, the characteristic of the syntactic foams are also observed to transition from dominant capacitive to dominant resistive behavior. This work was carried out at Southern University, Mechanical Engineering Department, Baton Rouge, LA 70802, United States of America.

Crack Identification in CFRP Laminated Beams Using Multi-Resolution Modal Teager–Kaiser Energy under Noisy Environments

PubMed Central

Xu, Wei; Cao, Maosen; Ding, Keqin; Radzieński, Maciej; Ostachowicz, Wiesław

2017-01-01

Carbon fiber reinforced polymer laminates are increasingly used in the aerospace and civil engineering fields. Identifying cracks in carbon fiber reinforced polymer laminated beam components is of considerable significance for ensuring the integrity and safety of the whole structures. With the development of high-resolution measurement technologies, mode-shape-based crack identification in such laminated beam components has become an active research focus. Despite its sensitivity to cracks, however, this method is susceptible to noise. To address this deficiency, this study proposes a new concept of multi-resolution modal Teager–Kaiser energy, which is the Teager–Kaiser energy of a mode shape represented in multi-resolution, for identifying cracks in carbon fiber reinforced polymer laminated beams. The efficacy of this concept is analytically demonstrated by identifying cracks in Timoshenko beams with general boundary conditions; and its applicability is validated by diagnosing cracks in a carbon fiber reinforced polymer laminated beam, whose mode shapes are precisely acquired via non-contact measurement using a scanning laser vibrometer. The analytical and experimental results show that multi-resolution modal Teager–Kaiser energy is capable of designating the presence and location of cracks in these beams under noisy environments. This proposed method holds promise for developing crack identification systems for carbon fiber reinforced polymer laminates. PMID:28773016

Experimental Investigations on the Pull-Out Behavior of Tire Strips Reinforced Sands.

PubMed

Li, Li-Hua; Chen, Yan-Jun; Ferreira, Pedro Miguel Vaz; Liu, Yong; Xiao, Heng-Lin

2017-06-27

Waste tires have excellent mechanical performance and have been used as reinforcing material in geotechnical engineering; however, their interface properties are poorly understood. To further our knowledge, this paper examines the pull-out characteristics of waste tire strips in a compacted sand, together with uniaxial and biaxial geogrids also tested under the same conditions. The analysis of the results shows that the interlocking effect and pull-out resistance between the tire strip and the sand is very strong and significantly higher than that of the geogrids. In the early stages of the pull-out test, the resistance is mainly provided by the front portion of the embedded tire strips, as the pull-out test continues, more and more of the areas towards the end of the tire strips are mobilized, showing a progressive failure mechanism. The deformations are proportional to the frictional resistance between the tire-sand interface, and increase as the normal stresses increase. Tire strips of different wear intensities were tested and presented different pull-out resistances; however, the pull-out resistance mobilization patterns were generally similar. The pull-out resistance values obtained show that rubber reinforcement can provide much higher pull-out forces than the geogrid reinforcements tested here, showing that waste tires are an excellent alternative as a reinforcing system, regardless of the environmental advantages.

Durability Characteristics Analysis of Plastic Worm Wheel with Glass Fiber Reinforced Polyamide.

PubMed

Kim, Gun-Hee; Lee, Jeong-Won; Seo, Tae-Il

2013-05-10

Plastic worm wheel is widely used in the vehicle manufacturing field because it is favorable for weight lightening, vibration and noise reduction, as well as corrosion resistance. However, it is very difficult for general plastics to secure the mechanical properties that are required for vehicle gears. If the plastic resin is reinforced by glass fiber in the fabrication process of plastic worm wheel, it is possible to achieve the mechanical properties of metallic material levels. In this study, the mechanical characteristic analysis of the glass-reinforced plastic worm wheel, according to the contents of glass fiber, is performed by analytic and experimental methods. In the case of the glass fiber-reinforced resin, the orientation and contents of glass fibers can influence the mechanical properties. For the characteristic prediction of plastic worm wheel, computer-aided engineering (CAE) analysis processes such as structural and injection molding analysis were executed with the polyamide resin reinforcement glass fiber (25 wt %, 50 wt %). The injection mold for fabricating the prototype plastic worm wheel was designed and made to reflect the CAE analysis results. Finally, the durability of prototype plastic worm wheel fabricated by the injection molding process was evaluated by the experimental method and the characteristics according to the glass fiber contents.

Durability Characteristics Analysis of Plastic Worm Wheel with Glass Fiber Reinforced Polyamide

PubMed Central

Kim, Gun-Hee; Lee, Jeong-Won; Seo, Tae-Il

2013-01-01

Plastic worm wheel is widely used in the vehicle manufacturing field because it is favorable for weight lightening, vibration and noise reduction, as well as corrosion resistance. However, it is very difficult for general plastics to secure the mechanical properties that are required for vehicle gears. If the plastic resin is reinforced by glass fiber in the fabrication process of plastic worm wheel, it is possible to achieve the mechanical properties of metallic material levels. In this study, the mechanical characteristic analysis of the glass-reinforced plastic worm wheel, according to the contents of glass fiber, is performed by analytic and experimental methods. In the case of the glass fiber-reinforced resin, the orientation and contents of glass fibers can influence the mechanical properties. For the characteristic prediction of plastic worm wheel, computer-aided engineering (CAE) analysis processes such as structural and injection molding analysis were executed with the polyamide resin reinforcement glass fiber (25 wt %, 50 wt %). The injection mold for fabricating the prototype plastic worm wheel was designed and made to reflect the CAE analysis results. Finally, the durability of prototype plastic worm wheel fabricated by the injection molding process was evaluated by the experimental method and the characteristics according to the glass fiber contents. PMID:28809248

Fabrication of ceramic substrate-reinforced and free forms

NASA Technical Reports Server (NTRS)

Quentmeyer, R. J.; Mcdonald, G.; Hendricks, R. C.

1985-01-01

Components fabricated of, or coated with, ceramics have lower parasitic cooling requirements. Techniques are discussed for fabricating thin-shell ceramic components and ceramic coatings for applications in rocket or jet engine environments. Thin ceramic shells with complex geometric forms involving convolutions and reentrant surfaces were fabricated by mandrel removal. Mandrel removal was combined with electroplating or plasma spraying and isostatic pressing to form a metal support for the ceramic. Rocket engine thrust chambers coated with 0.08 mm (3 mil) of ZrO2-8Y2O3 had no failures and a tenfold increase in engine life. Some measured mechanical properties of the plasma-sprayed ceramic are presented.

High-Temperature Polymer Composites Tested for Hypersonic Rocket Combustor Backup Structure

NASA Technical Reports Server (NTRS)

Sutter, James K.; Shin, E. Eugene; Thesken, John C.; Fink, Jeffrey E.

2005-01-01

Significant component weight reductions are required to achieve the aggressive thrust-toweight goals for the Rocket Based Combined Cycle (RBCC) third-generation, reusable liquid propellant rocket engine, which is one possible engine for a future single-stage-toorbit vehicle. A collaboration between the NASA Glenn Research Center and Boeing Rocketdyne was formed under the Higher Operating Temperature Propulsion Components (HOTPC) program and, currently, the Ultra-Efficient Engine Technology (UEET) Project to develop carbon-fiber-reinforced high-temperature polymer matrix composites (HTPMCs). This program focused primarily on the combustor backup structure to replace all metallic support components with a much lighter polymer-matrixcomposite- (PMC-) titanium honeycomb sandwich structure.

Behavior of fiber reinforced sandy slopes under seepage

USDA-ARS?s Scientific Manuscript database

Seepage flow is a major contributor to instability of natural hill slopes, river banks and engineered embankments. In order to increase the factor of safety, an emerging technology involves the inclusion of synthetic fibers in the soil. The addition of tension resisting fibers has a favorable effec...

Processing of fibre suspensions at ultra-high consistencies

Treesearch

Daniel F. Caulfield; Rodney E. Jacobson

2004-01-01

Typically the paper physicist considers pulp suspensions greater than 0.5% consistency as high consistency. In our research on cellulose fibre- reinforced engineering plastics we have had to develop a two-step method for the processing of fibers suspensions at ultrahigh consistencies (consistencies greater than 30%).

Damage-Tolerant, Affordable Composite Engine Cases Designed and Fabricated

NASA Technical Reports Server (NTRS)

Hopkins, Dale A.; Roberts, Gary D.; Pereira, J. Michael; Bowman, Cheryl L.

2005-01-01

An integrated team of NASA personnel, Government contractors, industry partners, and university staff have developed an innovative new technology for commercial fan cases that will substantially influence the safety and efficiency of future turbine engines. This effective team, under the direction of the NASA Glenn Research Center and with the support of the Federal Aviation Administration, has matured a new class of carbon/polymer composites and demonstrated a 30- to 50-percent improvement in specific containment capacity (blade fragment kinetic energy/containment system weight). As the heaviest engine component, the engine case/containment system greatly affects both the safety and efficiency of aircraft engines. The ballistic impact research team has developed unique test facilities and methods for screening numerous candidate material systems to replace the traditional heavy, metallic engine cases. This research has culminated in the selection of a polymer matrix composite reinforced with triaxially braided carbon fibers and technology demonstration through the fabrication of prototype engine cases for three major commercial engine manufacturing companies.

Antifriction basalt-plastics based on polypropylene

NASA Astrophysics Data System (ADS)

Bashtannik, P. I.; Ovcharenko, V. G.

1997-05-01

A study is made of the dependence of the mechanical and friction-engineering properties of polypropylene reinforced with basalt fibers on the viscosity of the polymer matrix. It is established that the main factors that determine the mechanical properties of the plastics are the quality of impregnation of the fibers by the binder and the residual length of the reinforcing filler in the composite after extrusion and injection molding. The material that was developed has a low friction coefficient and low rate of wear within a relatively brood range of friction conditions. The basalt-plastics can be used in the rubbing parts of machines and mechanisms subjected to dry friction.

Modeling delamination of FRP laminates under low velocity impact

NASA Astrophysics Data System (ADS)

Jiang, Z.; Wen, H. M.; Ren, S. L.

2017-09-01

Fiber reinforced plastic laminates (FRP) have been increasingly used in various engineering such as aeronautics, astronautics, transportation, naval architecture and their impact response and failure are a major concern in academic community. A new numerical model is suggested for fiber reinforced plastic composites. The model considers that FRP laminates has been constituted by unidirectional laminated plates with adhesive layers. A modified adhesive layer damage model that considering strain rate effects is incorporated into the ABAQUS / EXPLICIT finite element program by the user-defined material subroutine VUMAT. It transpires that the present model predicted delamination is in good agreement with the experimental results for low velocity impact.

FEM Analysis of Glass/Epoxy Composite Based Industrial Safety Helmet

NASA Astrophysics Data System (ADS)

Ram, Khushi; Bajpai, Pramendra Kumar

2017-08-01

Recently, the use of fiber reinforced polymer in every field of engineering (automobile, industry and aerospace) and medical has increased due to its distinctive mechanical properties. The fiber based polymer composites are more popular because these have high strength, light in weight, low cost and easily available. In the present work, the finite element analysis (FEA) of glass/epoxy composite based industrial safety helmet has been performed using solid-works simulation software. The modeling results show that glass fiber reinforced epoxy composite can be used as a material for fabrication of industrial safety helmet which has good mechanical properties than the existing helmet material.

Bond characteristics of steel fiber and deformed reinforcing steel bar embedded in steel fiber reinforced self-compacting concrete (SFRSCC)

NASA Astrophysics Data System (ADS)

Aslani, Farhad; Nejadi, Shami

2012-09-01

Steel fiber reinforced self-compacting concrete (SFRSCC) is a relatively new composite material which congregates the benefits of the self-compacting concrete (SCC) technology with the profits derived from the fiber addition to a brittle cementitious matrix. Steel fibers improve many of the properties of SCC elements including tensile strength, ductility, toughness, energy absorption capacity, fracture toughness and cracking. Although the available research regarding the influence of steel fibers on the properties of SFRSCC is limited, this paper investigates the bond characteristics between steel fiber and SCC firstly. Based on the available experimental results, the current analytical steel fiber pullout model (Dubey 1999) is modified by considering the different SCC properties and different fiber types (smooth, hooked) and inclination. In order to take into account the effect of fiber inclination in the pullout model, apparent shear strengths ( τ ( app)) and slip coefficient ( β) are incorporated to express the variation of pullout peak load and the augmentation of peak slip as the inclined angle increases. These variables are expressed as functions of the inclined angle ( ϕ). Furthurmore, steel-concrete composite floors, reinforced concrete floors supported by columns or walls and floors on an elastic foundations belong to the category of structural elements in which the conventional steel reinforcement can be partially replaced by the use of steel fibers. When discussing deformation capacity of structural elements or civil engineering structures manufactured using SFRSCC, one must be able to describe thoroughly both the behavior of the concrete matrix reinforced with steel fibers and the interaction between this composite matrix and discrete steel reinforcement of the conventional type. However, even though the knowledge on bond behavior is essential for evaluating the overall behavior of structural components containing reinforcement and steel fibers, information is hardly available in this area. In this study, bond characteristics of deformed reinforcing steel bars embedded in SFRSCC is investigated secondly.

Structural Performance’s Optimally Analysing and Implementing Based on ANSYS Technology

NASA Astrophysics Data System (ADS)

Han, Na; Wang, Xuquan; Yue, Haifang; Sun, Jiandong; Wu, Yongchun

2017-06-01

Computer-aided Engineering (CAE) is a hotspot both in academic field and in modern engineering practice. Analysis System(ANSYS) simulation software for its excellent performance become outstanding one in CAE family, it is committed to the innovation of engineering simulation to help users to shorten the design process, improve product innovation and performance. Aimed to explore a structural performance’s optimally analyzing model for engineering enterprises, this paper introduced CAE and its development, analyzed the necessity for structural optimal analysis as well as the framework of structural optimal analysis on ANSYS Technology, used ANSYS to implement a reinforced concrete slab structural performance’s optimal analysis, which was display the chart of displacement vector and the chart of stress intensity. Finally, this paper compared ANSYS software simulation results with the measured results,expounded that ANSYS is indispensable engineering calculation tools.

Active Learning in Engineering Education: a (re)introduction

NASA Astrophysics Data System (ADS)

Lima, Rui M.; Andersson, Pernille Hammar; Saalman, Elisabeth

2017-01-01

The informal network 'Active Learning in Engineering Education' (ALE) has been promoting Active Learning since 2001. ALE creates opportunity for practitioners and researchers of engineering education to collaboratively learn how to foster learning of engineering students. The activities in ALE are centred on the vision that learners construct their knowledge based on meaningful activities and knowledge. In 2014, the steering committee of the ALE network reinforced the need to discuss the meaning of Active Learning and that was the base for this proposal for a special issue. More than 40 submissions were reviewed by the European Journal of Engineering Education community and this theme issue ended up with eight contributions, which are different both in their research and Active Learning approaches. These different Active Learning approaches are aligned with the different approaches that can be increasingly found in indexed journals.

Self-lubricating Al-WS2 composites for efficient and greener tribological parts.

PubMed

Niste, Vlad Bogdan; Ratoi, Monica; Tanaka, Hiroyoshi; Xu, Fang; Zhu, Yanqiu; Sugimura, Joichi

2017-11-07

Due to their mechanical and physical properties, aluminium alloys possess wide potential in the automotive industry, particularly in hot reciprocating applications such as pistons for diesel and petrol engines. WS 2 particle-reinforced composites could bring further improvements by reducing friction and wear between moving parts. Reducing friction improves efficiency by lowering energy/fuel use, ultimately leading to lower greenhouse gas emissions, while antiwear properties can prolong component life. This study compares for the first time the tribological performance of powder metallurgy-consolidated Al composites reinforced with either IF- or 2H-WS 2 particles, so as to elucidate their mechanism of action in test conditions similar to those encountered in engine applications. The composites were tested in lubricated reciprocating contacts against AISI52100 steel balls and the impact of WS 2 could be seen at both 25 and 100 °C. The reduced friction and wear at ambient temperature is due to the predominantly physical mechanism of action of WS 2 , while the best antiwear performance is measured at elevated (standard operating engine) temperatures that promote the chemical reaction of WS 2 with the aluminium matrix. The investigation focused on studying the wear tracks/scars and the tribofilms generated on the composite and ball with optical profilometry, SEM, XPS and Auger spectroscopy.

Resistance of Plastics to Outdoor Weathering. Glass Filament Wound Epoxies.

DTIC Science & Technology

This report presents results on the aging and natural weathering of filament-wound, glass -reinforced epoxy resin systems for use as engineering...materials for Army rocket motor cases. Specimens (cylinders 9 inches long and 3 inches in diameter, using either E or S glass with various resin systems

Beyond the University to Mass Higher Education

ERIC Educational Resources Information Center

Maclure, Stuart

1973-01-01

"Life-long education," a spin-off mass secondary education, born of egalitarianism in education, reinforced by technological exigences, is a concept that needs close examination for it contains the seed of illiberality just as it offers a means of social engineering and a commitment to an open society. (JH)

Bioactive Cellulose Nanocrystal Reinforced 3D Printable Poly(epsilon-caprolactone) Nanocomposite for Bone Tissue Engineering

NASA Astrophysics Data System (ADS)

Hong, Jung Ki

Polymeric bone scaffolds are a promising tissue engineering approach for the repair of critical-size bone defects. Porous three-dimensional (3D) scaffolds play an essential role as templates to guide new tissue formation. However, there are critical challenges arising from the poor mechanical properties and low bioactivity of bioresorbable polymers, such as poly(a-caprolactone) (PCL) in bone tissue engineering applications. This research investigates the potential use of cellulose nanocrystals (CNCs) as multi-functional additives that enhance the mechanical properties and increase the biomineralization rate of PCL. To this end, an in vitro biomineralization study of both sulfuric acid hydrolyzed- CNCs (SH-CNCs) and surface oxidized-CNCs (SO-CNCs) has been performed in simulated body fluid in order to evaluate the bioactivity of the surface functional groups, sulfate and carboxyl groups, respectively. PCL nanocomposites were prepared with different SO-CNC contents and the chemical/physical properties of the nanocomposites were analyzed. 3D porous scaffolds with fully interconnected pores and well-controlled pore sizes were fabricated from the PCL nanocomposites with a 3D printer. The mechanical stability of the scaffolds were studied using creep test under dry and submersion conditions. Lastly, the biocompatibility of CNCs and 3D printed porous scaffolds were assessed in vitro.. The carboxyl groups on the surface of SO-CNCs provided a significantly improved calcium ion binding ability which could play an important role in the biomineralization (bioactivity) by induction of mineral formation for bone tissue engineering applications. In addition, the mechanical properties of porous PCL nanocomposite scaffolds were pronouncedly reinforced by incorporation of SO-CNCs. Both the compressive modulus and creep resistance of the PCL scaffolds were enhanced either in dry or in submersion conditions at 37 °C. Lastly, the biocompatibility study demonstrated that both the CNCs and material fabrication processes (e.g., PCL nanocomposites and 3D printing) were not toxic to the preosteoblasts (MC3T3 cells). Also, the SO-CNCs showed a positive effect on biomineralization of PCL scaffolds (i.e., accelerated calcium or mineral deposits on the surface of the scaffolds) during in vitro study. Overall, the SO-CNCs could play a critical role in the development of scaffold materials as a potential candidate for reinforcing nanofillers in bone tissue engineering applications.

MoSi2-Base Hybrid Composite Passed Engine Test

NASA Technical Reports Server (NTRS)

Keith, Theo G., Jr.; Hebsur, Mohan

1998-01-01

The intermetallics compound molybdenum disilicide (MoSi2) is an attractive high-temperature structural material for advanced engine applications. It has excellent oxidation resistance, a high melting point, relatively low density, and high thermal conductivity, and it is easily machined. Past research'at the NASA Lewis Research Center has resulted in the development of a hybrid composite consisting of a MoSi2 matrix reinforced with silicon nitride (Si3N4) Particulate and silicon carbide (SiC) fibers. This composite has demonstrated attractive strength, toughness, thermal fatigue, and oxidation resistance, including resistance to "pest" oxidation. These properties attracted the interest of the Office of Naval Research and Pratt & Whitney, and a joint NASA/Navy/Pratt & Whitney effort was developed to continue to mature the MoSi2 Composite technology. A turbine blade outer air seal, which was part of the Integrated High Performance Turbine Engine Technology (IHPTET) program, was chosen as a first component on which to focus. The first tasks of the materials development effort were to develop improved processing methods to reduce costs and to use fine-diameter fibers that enable the manufacturing of complex shapes. Tape-casting methods were developed to fully infiltrate the fine SiC fibers with matrix powders. The resulting composites were hot pressed to 100-percent density. Composites with cross-plied fiber architectures with 30 vol. % hi-nicalon SiC fibers and 30 vol. % nitride particles are now made routinely and demonstrate a good balance of properties. The next task entailed the measurement of a wide variety of mechanical properties to confirm the suitability of this composite in engines. In particular, participants in this effort demonstrated that composites made with Hi-Nicalon fibers had strength and toughness properties equal to or better than those of the composites made with the large-diameter fibers that had been used previously. Another critically important property measured was impact resistance. Aircraft engine components require sufficient toughness to resist manufacturing defects, assembly damage, stress concentrations at notches, and foreign object damage. Engine company designers indicated that impact resistance would have to be measured before they would seriously consider these types of composites. The Charpy V-notch test was chosen to assess impact resistance, and both monolithic and composite versions Of MOSi2 were tested from -300 to 1400 C. The results (see the following graphs) show that nitride-particulate-reinforced MoSi2 exhibited impact resistance higher than that of many monolithic ceramics and intermetallics, and that the fiber-reinforced composites had even higher values, approaching that of cast superalloys.

Think first job! Preferences and expectations of engineering students in a French `Grande Ecole'

NASA Astrophysics Data System (ADS)

Gerwel Proches, Cecile N.; Chelin, Nathalie; Rouvrais, Siegfried

2018-03-01

A career in engineering may be appealing owing to the prospect of a good salary and a dynamic work environment. There may, however, be challenges for students wishing to enter their first job. In engineering education, career preparation courses may be included so as to prepare students adequately for their first job, future careers, and to reinforce career decision-making skills. This study explored the first-job preferences and expectations of engineering students at a generalist French 'Grande Ecole' before their compulsory internship. The study ultimately provided insight into ways in which future engineers may best be equipped for their first jobs. A qualitative research study was employed, using four focus groups to collect data, which was analysed thematically. Key findings indicate the resolute importance that engineering students place on having a challenging job, teamwork, independence, opportunities for development, and a participative style of being managed. The research findings may be of value in order to renew an engineering curriculum with better alignment between students' expectations and industry needs.

Fabrication of ceramic substrate-reinforced and free forms by mandrel plasma spraying metal-ceramic composites

NASA Technical Reports Server (NTRS)

Quentmeyer, R. J.; Mcdonald, G.; Hendricks, R. C.

1985-01-01

Components fabricated of, or coated with, ceramics have lower parasitic cooling requirements. Techniques are discussed for fabricating thin-shell ceramic components and ceramic coatings for applications in rocket or jet engine environments. Thin ceramic shells with complex geometric forms involving convolutions and reentrant surfaces were fabricated by mandrel removal. Mandrel removal was combined with electroplating or plasma spraying and isostatic pressing to form a metal support for the ceramic. Rocket engine thrust chambers coated with 0.08 mm (3 mil) of ZrO2-8Y2O3 had no failures and a tenfold increase in engine life. Some measured mechanical properties of the plasma-sprayed ceramic are presented.

Strain analysis of nanowire interfaces in multiscale composites

NASA Astrophysics Data System (ADS)

Malakooti, Mohammad H.; Zhou, Zhi; Spears, John H.; Shankwitz, Timothy J.; Sodano, Henry A.

2016-04-01

Recently, the reinforcement-matrix interface of fiber reinforced polymers has been modified through grafting nanostructures - particularly carbon nanotubes and ZnO nanowires - on to the fiber surface. This type of interface engineering has made a great impact on the development of multiscale composites that have high stiffness, interfacial strength, toughness, and vibrational damping - qualities that are mutually exclusive to a degree in most raw materials. Although the efficacy of such nanostructured interfaces has been established, the reinforcement mechanisms of these multiscale composites have not been explored. Here, strain transfer across a nanowire interphase is studied in order to gain a heightened understanding of the working principles of physical interface modification and the formation of a functional gradient. This problem is studied using a functionally graded piezoelectric interface composed of vertically aligned lead zirconate titanate nanowires, as their piezoelectric properties can be utilized to precisely control the strain on one side of the interface. The displacement and strain across the nanowire interface is captured using digital image correlation. It is demonstrated that the material gradient created through nanowires cause a smooth strain transfer from reinforcement phase into matrix phase that eliminates the stress concentration between these phases, which have highly mismatched elasticity.

An Innovative Approach to Control Steel Reinforcement Corrosion by Self-Healing.

PubMed

Koleva, Dessi A

2018-02-20

The corrosion of reinforced steel, and subsequent reinforced concrete degradation, is a major concern for infrastructure durability. New materials with specific, tailor-made properties or the establishment of optimum construction regimes are among the many approaches to improving civil structure performance. Ideally, novel materials would carry self-repairing or self-healing capacities, triggered in the event of detrimental influence and/or damage. Controlling or altering a material's behavior at the nano-level would result in traditional materials with radically enhanced properties. Nevertheless, nanotechnology applications are still rare in construction, and would break new ground in engineering practice. An approach to controlling the corrosion-related degradation of reinforced concrete was designed as a synergetic action of electrochemistry, cement chemistry and nanotechnology. This contribution presents the concept of the approach, namely to simultaneously achieve steel corrosion resistance and improved bulk matrix properties. The technical background and challenges for the application of polymeric nanomaterials in the field are briefly outlined in view of this concept, which has the added value of self-healing. The credibility of the approach is discussed with reference to previously reported outcomes, and is illustrated via the results of the steel electrochemical responses and microscopic evaluations of the discussed materials.

Energy-dissipating and self-repairing SMA-ECC composite material system

NASA Astrophysics Data System (ADS)

Li, Xiaopeng; Li, Mo; Song, Gangbing

2015-02-01

Structural component ductility and energy dissipation capacity are crucial factors for achieving reinforced concrete structures more resistant to dynamic loading such as earthquakes. Furthermore, limiting post-event residual damage and deformation allows for immediate re-operation or minimal repairs. These desirable characteristics for structural ‘resilience’, however, present significant challenges due to the brittle nature of concrete, its deformation incompatibility with ductile steel, and the plastic yielding of steel reinforcement. Here, we developed a new composite material system that integrates the unique ductile feature of engineered cementitious composites (ECC) with superelastic shape memory alloy (SMA). In contrast to steel reinforced concrete (RC) and SMA reinforced concrete (SMA-RC), the SMA-ECC beams studied in this research exhibited extraordinary energy dissipation capacity, minimal residual deformation, and full self-recovery of damage under cyclic flexural loading. We found that the tensile strain capacity of ECC, tailored up to 5.5% in this study, allows it to work compatibly with superelastic SMA. Furthermore, the distributed microcracking damage mechanism in ECC is critical for sufficient and reliable recovery of damage upon unloading. This research demonstrates the potential of SMA-ECC for improving resilience of concrete structures under extreme hazard events.

An Innovative Approach to Control Steel Reinforcement Corrosion by Self-Healing

PubMed Central

2018-01-01

The corrosion of reinforced steel, and subsequent reinforced concrete degradation, is a major concern for infrastructure durability. New materials with specific, tailor-made properties or the establishment of optimum construction regimes are among the many approaches to improving civil structure performance. Ideally, novel materials would carry self-repairing or self-healing capacities, triggered in the event of detrimental influence and/or damage. Controlling or altering a material’s behavior at the nano-level would result in traditional materials with radically enhanced properties. Nevertheless, nanotechnology applications are still rare in construction, and would break new ground in engineering practice. An approach to controlling the corrosion-related degradation of reinforced concrete was designed as a synergetic action of electrochemistry, cement chemistry and nanotechnology. This contribution presents the concept of the approach, namely to simultaneously achieve steel corrosion resistance and improved bulk matrix properties. The technical background and challenges for the application of polymeric nanomaterials in the field are briefly outlined in view of this concept, which has the added value of self-healing. The credibility of the approach is discussed with reference to previously reported outcomes, and is illustrated via the results of the steel electrochemical responses and microscopic evaluations of the discussed materials. PMID:29461495

Experimental Investigations on the Pull-Out Behavior of Tire Strips Reinforced Sands

PubMed Central

Li, Li-Hua; Chen, Yan-Jun; Ferreira, Pedro Miguel Vaz; Liu, Yong; Xiao, Heng-Lin

2017-01-01

Waste tires have excellent mechanical performance and have been used as reinforcing material in geotechnical engineering; however, their interface properties are poorly understood. To further our knowledge, this paper examines the pull-out characteristics of waste tire strips in a compacted sand, together with uniaxial and biaxial geogrids also tested under the same conditions. The analysis of the results shows that the interlocking effect and pull-out resistance between the tire strip and the sand is very strong and significantly higher than that of the geogrids. In the early stages of the pull-out test, the resistance is mainly provided by the front portion of the embedded tire strips, as the pull-out test continues, more and more of the areas towards the end of the tire strips are mobilized, showing a progressive failure mechanism. The deformations are proportional to the frictional resistance between the tire-sand interface, and increase as the normal stresses increase. Tire strips of different wear intensities were tested and presented different pull-out resistances; however, the pull-out resistance mobilization patterns were generally similar. The pull-out resistance values obtained show that rubber reinforcement can provide much higher pull-out forces than the geogrid reinforcements tested here, showing that waste tires are an excellent alternative as a reinforcing system, regardless of the environmental advantages. PMID:28773069

Structural health monitoring and damage evaluation for steel confined reinforced concrete column using the acoustic emission technique

NASA Astrophysics Data System (ADS)

Du, Fangzhu; Li, Dongsheng

2018-03-01

As a new kind of composite structures, the using of steel confined reinforced concrete column attract increasing attention in civil engineer. During the damage process, this new structure offers highly complex and invisible failure mechanism due to the combination effects of steel tubes, concrete, and steel rebar. Acoustic emission (AE) technique has been extensively studied in nondestructive testing (NDT) and is currently applied in civil engineering for structural health monitoring (SHM) and damage evaluation. In the present study, damage property and failure evolution of steel confined and unconfined reinforced concrete (RC) columns are investigated under quasi-static loading through (AE) signal. Significantly improved loading capacity and excellent energy dissipation characteristic demonstrated the practicality of that proposed structure. AE monitoring results indicated that the progressive deformation of the test specimens occur in three stages representing different damage conditions. Sentry function compares the logarithm ratio between the stored strain energy (Es) and the released acoustic energy (Ea); explicitly disclose the damage growth and failure mechanism of the test specimens. Other extended AE features including index of damage (ID), and relax ratio are calculated to quantitatively evaluate the damage severity and critical point. Complicated temporal evolution of different AE features confirms the potential importance of integrated analysis of two or more parameters. The proposed multi-indicators analysis is capable of revealing the damage growth and failure mechanism for steel confined RC columns, and providing critical warning information for structure failure.

Laboratory study on subgrade soil stabilization using RBI grade 81

NASA Astrophysics Data System (ADS)

Cynthia, J. Bernadette; Kamalambikai, B.; Prasanna Kumar, R.; Dharini, K.

2017-07-01

The present study investigates the effect of reinforcing the sub grade soils with RBI 81 material. A soil nearby was collected and preliminary tests were conducted to classify the soil and it was found from the results that the sample collected was a poorly graded clay. Subsequently Tests such as Proctor Compaction, CBR, and UCC were conducted to study the various engineering properties of the identified soil. In addition to the above tests were also conducted on the soil by reinforcing with varying percentages of RBI 81. From the analysis of test results it was found that this material (RBI 81) will significantly improve the CBR value of the soil.

Constitutive Models for Design of Sustainable Concrete Structures

NASA Astrophysics Data System (ADS)

Brozovsky, J.; Cajka, R.; Koktan, J.

2018-04-01

The paper deals with numerical models of reinforced concrete which are expected to be useful to enhance design of sustainable reinforced concrete structures. That is, the models which can deliver higher precision of results than the linear elastic models but which are still feasible for engineering practice. Such models can be based on an elastic-plastic material. The paper discusses properties of such models. A material model based of the Chen criteria and the Ohtani hardening model for concrete was selected for further development. There is also given a comparison of behaviour of such model with behaviour of a more complex smeared crack model which is based on principles of fracture mechanics.

Industry to Education Technology Transfer Program. Composite Materials--Personnel Development. Final Report.

ERIC Educational Resources Information Center

Tomezsko, Edward S. J.

A composite materials education program was established to train Boeing Helicopter Company employees in the special processing of new filament-reinforced polymer composite materials. During the personnel development phase of the joint Boeing-Penn State University project, an engineering instructor from Penn State completed a 5-month, full-time…

Powering the Future: A Wind Turbine Design Challenge

ERIC Educational Resources Information Center

Pries, Caitlin Hicks; Hughes, Julie

2011-01-01

Nothing brings out the best in eighth-grade physical science students quite like an engineering challenge. The wind turbine design challenge described in this article has proved to be a favorite among students with its focus on teamwork and creativity and its (almost) sneaky reinforcement of numerous physics concepts. For this activity, pairs of…

Engineering Design Handbook. Discontinuous Fiberglass Reinforced Thermoplastics

DTIC Science & Technology

1981-04-01

Fiberglass Type and Form Glass fibers are...Hall, Ltd. Figure 2-11. Stress vs Volume of Glass Fiber for Nylon and Polypropylene Glass Fiber E glass 12 Mm diam. Fibreglass Ltd Size ref...good dispersion of fiberglass in the end product with pelletized feed stocks. Glass fiber attrition is minimized with the dry blend technique,

Development and Evaluation of Mechatronics Learning System in a Web-Based Environment

ERIC Educational Resources Information Center

Shyr, Wen-Jye

2011-01-01

The development of remote laboratory suitable for the reinforcement of undergraduate level teaching of mechatronics is important. For the reason, a Web-based mechatronics learning system, called the RECOLAB (REmote COntrol LABoratory), for remote learning in engineering education has been developed in this study. The web-based environment is an…

Become a Star: Teaching the Process of Design and Implementation of an Intelligent System

ERIC Educational Resources Information Center

Venables, Anne; Tan, Grace

2005-01-01

Teaching future knowledge engineers, the necessary skills for designing and implementing intelligent software solutions required by business, industry and research today, is a very tall order. These skills are not easily taught in traditional undergraduate computer science lectures; nor are the practical experiences easily reinforced in laboratory…

Students' Assessment of Interactive Distance Experimentation in Nuclear Reactor Physics Laboratory Education

ERIC Educational Resources Information Center

Malkawi, Salaheddin; Al-Araidah, Omar

2013-01-01

Laboratory experiments develop students' skills in dealing with laboratory instruments and physical processes with the objective of reinforcing the understanding of the investigated subject. In nuclear engineering, where research reactors play a vital role in the practical education of students, the high cost and long construction time of research…

Applied STEM Coursework, High School Dropout Rates, and Students with Learning Disabilities

ERIC Educational Resources Information Center

Plasman, Jay Stratte; Gottfried, Michael A.

2018-01-01

Applied science, technology, engineering, and math (STEM) coursetaking is becoming more commonplace in traditional high school settings to help students reinforce their learning in academic STEM courses. Throughout U.S. educational history, vocational education has been a consistent focus for schools to keep students on the school-to-career…

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (right) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System. will be available to discuss the work and answer questions.

NASA Image and Video Library

2003-09-26

KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (right) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System. will be available to discuss the work and answer questions.

Analytical Prediction of the Seismic Response of a Reinforced Concrete Containment Vessel

DOE Office of Scientific and Technical Information (OSTI.GOV)

James, R.J.; Rashid, Y.R.; Cherry, J.L.

Under the sponsorship of the Ministry of International Trade and Industry (MITI) of Japan, the Nuclear Power Engineering Corporation (NUPEC) is investigating the seismic behavior of a Reinforced Concrete Containment Vessel (RCCV) through scale-model testing using the high-performance shaking table at the Tadotsu Engineering Laboratory. A series of tests representing design-level seismic ground motions was initially conducted to gather valuable experimental measurements for use in design verification. Additional tests will be conducted with increasing amplifications of the seismic input until a structural failure of the test model occurs. In a cooperative program with NUPEC, the US Nuclear Regulatory Commission (USNRC),more » through Sandia National Laboratories (SNL), is conducting analytical research on the seismic behavior of RCCV structures. As part of this program, pretest analytical predictions of the model tests are being performed. The dynamic time-history analysis utilizes a highly detailed concrete constitutive model applied to a three-dimensional finite element representation of the test structure. This paper describes the details of the analysis model and provides analysis results.« less

KENNEDY SPACE CENTER, FLA. - Local Central Florida television reporters Phil Robertson (left), with WFTV, and Dan Billow (right), with WESH, tape commentaries after a media tour of the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

NASA Image and Video Library

2003-09-26

KENNEDY SPACE CENTER, FLA. - Local Central Florida television reporters Phil Robertson (left), with WFTV, and Dan Billow (right), with WESH, tape commentaries after a media tour of the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

Recent developments in multi-layer flat knitting technology for waste free production of complex shaped 3D-reinforcing structures for composites

NASA Astrophysics Data System (ADS)

Trümper, W.; Lin, H.; Callin, T.; Bollengier, Q.; Cherif, C.; Krzywinski, S.

2016-07-01

Constantly increasing prices for raw materials and energy as well as the current discourse on the reduction of CO2-emissions places a special emphasis on the advantages of lightweight constructions and its resource conserving production methods. Fibre-reinforced composites are already seeing a number of applications in automobile, energy and mechanical engineering. Future applications within the named areas require greater material and energy efficiency and therefore manufacturing methods for textile preforms and lightweight constructions enabling an optimal arrangement of the reinforcing fibres while in the same time limiting waste to a minimum. One manufacturing method for textile reinforced preforms fulfilling quite many of the named requirements is the multilayer weft knitting technology. Multilayer weft knitted fabrics containing straight reinforcing yarns at least in two directions. The arrangement of these yarns is fixed by the loop yarn. Used yarn material in each knitting row is adaptable e. g. according to the load requirements or for the local integration of sensors. Draping properties of these fabrics can be varied within a great range and through this enabling draping of very complex shaped 3D-preforms without wrinkles from just one uncut fabric. The latest developments at ITM are concentrating on the development of a full production chain considering the 3D-CAD geometry, the load analysis, the generation of machine control programs as well as the development of technology and machines to enable the manufacturing of innovative net shape 3D-multilayer weft knitted fabrics such as complex shaped spacer fabrics and tubular fabrics with biaxial reinforcement.

UCS-PROMOVE: The engineer of the future

NASA Astrophysics Data System (ADS)

Villas-Boas, V.

2010-06-01

The Universidade de Caxias do Sul (UCS) elaborated the cooperative project called 'The engineer of the future', with the objective of promoting science and engineering among high school teachers and students. This project aims to improve the quality of the teaching and to increase the interest of students in technological areas, leading to a future career in engineering. The activities of this project were planned to give meaning and foundation to the teaching-learning process of science and for the application of theory in the solution of real problems, while articulating scientific, economic, environmental, social and political aspects and also to reinforce the important role of engineering in society. Amongst the activities to be offered to high school teachers and students are a specialisation course for teachers based upon new educational methodologies, workshops in different areas of science and technology, a programme entitled 'Encouraging girls in technology, science and engineering', science fairs and visits to the industries of the region. Activities with the engineering instructors of UCS are also being developed in order to help them to incorporate in their classes more effective pedagogical strategies for educating the engineer-to-be.

Applications of Cosmic Ray Muon Radiography

NASA Astrophysics Data System (ADS)

Guardincerri, E.; Durham, J. M.; Morris, C. L.; Rowe, C. A.; Poulson, D. C.; Bacon, J. D.; Plaud-Ramos, K.; Morley, D. J.

2015-12-01

The Dome of Santa Maria del Fiore, Florence Cathedral, was built between 1420 and 1436 by architect Filippo Brunelleschi and it is now cracking under its own weight. Engineering efforts are underway to model the dome's structure and reinforce it against further deterioration. According to some scholars, Brunelleschi might have built reinforcement structures into the dome itself; however, the only confirmed known subsurface reinforcement is a chain of iron and stone around the dome's base. Tomography with cosmic ray muons is a non-destructive imaging method that can be used to image the interior of the wall and therefore ascertain the layout and status of any iron substructure in the dome. We will show the results from a muon tomography measurement of iron hidden in a mockup of the dome's wall performed at Los Alamos National Lab in 2015. The sensitivity of this technique, and the status of this project will be also discussed. At last, we will show results on muon attenuation radiography of larger shallow targets.

Multifunctional Nano-engineered Polymer Surfaces with Enhanced Mechanical Resistance and Superhydrophobicity

NASA Astrophysics Data System (ADS)

Hernández, Jaime J.; Monclús, Miguel A.; Navarro-Baena, Iván; Viela, Felipe; Molina-Aldareguia, Jon M.; Rodríguez, Isabel

2017-03-01

This paper presents a multifunctional polymer surface that provides superhydrophobicity and self-cleaning functions together with an enhancement in mechanical and electrical performance. These functionalities are produced by nanoimprinting high aspect ratio pillar arrays on polymeric matrix incorporating functional reinforcing elements. Two distinct matrix-filler systems are investigated specifically, Carbon Nanotube reinforced Polystyrene (CNT-PS) and Reduced Graphene Oxide reinforced Polyvinylidene Difluoride (RGO-PVDF). Mechanical characterization of the topographies by quantitative nanoindentation and nanoscratch tests are performed to evidence a considerable increase in stiffness, Young’s modulus and critical failure load with respect to the pristine polymers. The improvement on the mechanical properties is rationalized in terms of effective dispersion and penetration of the fillers into the imprinted structures as determined by confocal Raman and SEM studies. In addition, an increase in the degree of crystallization for the PVDF-RGO imprinted nanocomposite possibly accounts for the larger enhancement observed. Improvement of the mechanical ruggedness of functional textured surfaces with appropriate fillers will enable the implementation of multifunctional nanotextured materials in real applications.

Thermal analysis of GFRP-reinforced continuous concrete decks subjected to top fire

NASA Astrophysics Data System (ADS)

Hawileh, Rami A.; Rasheed, Hayder A.

2017-12-01

This paper presents a numerical study that investigates the behavior of continuous concrete decks doubly reinforced with top and bottom glass fiber reinforced polymer (GFRP) bars subjected to top surface fire. A finite element (FE) model is developed and a detailed transient thermal analysis is performed on a continuous concrete bridge deck under the effect of various fire curves. A parametric study is performed to examine the top cover thickness and the critical fire exposure curve needed to fully degrade the top GFRP bars while achieving certain fire ratings for the deck considered. Accordingly, design tables are prepared for each fire curve to guide the engineer to properly size the top concrete cover and maintain the temperature in the GFRP bars below critical design values in order to control the full top GFRP degradation. It is notable to indicate that degradation of top GFRP bars do not pose a collapse hazard but rather a serviceability concern since cracks in the negative moment region widen resulting in simply supported spans.

Nanocellulose reinforced gellan-gum hydrogels as potential biological substitutes for annulus fibrosus tissue regeneration.

PubMed

Pereira, Diana R; Silva-Correia, Joana; Oliveira, Joaquim M; Reis, Rui L; Pandit, Abhay; Biggs, Manus J

2018-04-01

Intervertebral disc (IVD) degeneration is associated with both structural damage and aging related degeneration. Annulus fibrosus (AF) defects such as annular tears, herniation and discectomy require novel tissue engineering strategies to functionally repair AF tissue. An ideal construct will repair the AF by providing physical and biological support, facilitating regeneration. The presented strategy herein proposes a gellan gum-based construct reinforced with cellulose nanocrystals (nCell) as a biological self-gelling AF substitute. Nanocomposite hydrogels were fabricated and characterized with respect to hydrogel swelling capacity, degradation rate in vitro and mechanical properties. Rheological evaluation on the nanocomposites demonstrated the GGMA reinforcement with nCell promoted matrix entanglement with higher scaffold stiffness observed upon ionic crosslinking. Compressive mechanical tests demonstrated compressive modulus values close to those of the human AF tissue. Furthermore, cell culture studies with encapsulated bovine AF cells indicated that nanocomposite constructs promoted cell viability and a physiologically relevant cell morphology for up to fourteen days in vitro. Copyright © 2017 Elsevier Inc. All rights reserved.

The Particle Shape of WC Governing the Fracture Mechanism of Particle Reinforced Iron Matrix Composites.

PubMed

Li, Zulai; Wang, Pengfei; Shan, Quan; Jiang, Yehua; Wei, He; Tan, Jun

2018-06-11

In this work, tungsten carbide particles (WC p , spherical and irregular particles)-reinforced iron matrix composites were manufactured utilizing a liquid sintering technique. The mechanical properties and the fracture mechanism of WC p /iron matrix composites were investigated theoretically and experimentally. The crack schematic diagram and fracture simulation diagram of WC p /iron matrix composites were summarized, indicating that the micro-crack was initiated both from the interface for spherical and irregular WC p /iron matrix composites. However, irregular WC p had a tendency to form spherical WC p . The micro-cracks then expanded to a wide macro-crack at the interface, leading to a final failure of the composites. In comparison with the spherical WC p , the irregular WC p were prone to break due to the stress concentration resulting in being prone to generating brittle cracking. The study on the fracture mechanisms of WC p /iron matrix composites might provide a theoretical guidance for the design and engineering application of particle reinforced composites.

Flow Navigation by Smart Microswimmers via Reinforcement Learning

NASA Astrophysics Data System (ADS)

Colabrese, Simona; Gustavsson, Kristian; Celani, Antonio; Biferale, Luca

2017-04-01

Smart active particles can acquire some limited knowledge of the fluid environment from simple mechanical cues and exert a control on their preferred steering direction. Their goal is to learn the best way to navigate by exploiting the underlying flow whenever possible. As an example, we focus our attention on smart gravitactic swimmers. These are active particles whose task is to reach the highest altitude within some time horizon, given the constraints enforced by fluid mechanics. By means of numerical experiments, we show that swimmers indeed learn nearly optimal strategies just by experience. A reinforcement learning algorithm allows particles to learn effective strategies even in difficult situations when, in the absence of control, they would end up being trapped by flow structures. These strategies are highly nontrivial and cannot be easily guessed in advance. This Letter illustrates the potential of reinforcement learning algorithms to model adaptive behavior in complex flows and paves the way towards the engineering of smart microswimmers that solve difficult navigation problems.

Finite-Element Analysis of Crack Arrest Properties of Fiber Reinforced Composites Application in Semi-Elliptical Cracked Pipelines

NASA Astrophysics Data System (ADS)

Wang, Linyuan; Song, Shulei; Deng, Hongbo; Zhong, Kai

2018-04-01

In nowadays, repair method using fiber reinforced composites as the mainstream pipe repair technology, it can provide security for X100 high-grade steel energy long-distance pipelines in engineering. In this paper, analysis of cracked X100 high-grade steel pipe was conducted, simulation analysis was made on structure of pipes and crack arresters (CAs) to obtain the J-integral value in virtue of ANSYS Workbench finite element software and evaluation on crack arrest effects was done through measured elastic-plastic fracture mechanics parameter J-integral and the crack arrest coefficient K, in a bid to summarize effect laws of composite CAs and size of pipes and cracks for repairing CAs. The results indicate that the K value is correlated with laying angle λ, laying length L2/D1, laying thickness T1/T2of CAs, crack depth c/T1 and crack length a/c, and calculate recommended parameters for repairing fiber reinforced composite CAs in terms of two different crack forms.

Implementation of real-time energy management strategy based on reinforcement learning for hybrid electric vehicles and simulation validation

PubMed Central

Kong, Zehui; Liu, Teng

2017-01-01

To further improve the fuel economy of series hybrid electric tracked vehicles, a reinforcement learning (RL)-based real-time energy management strategy is developed in this paper. In order to utilize the statistical characteristics of online driving schedule effectively, a recursive algorithm for the transition probability matrix (TPM) of power-request is derived. The reinforcement learning (RL) is applied to calculate and update the control policy at regular time, adapting to the varying driving conditions. A facing-forward powertrain model is built in detail, including the engine-generator model, battery model and vehicle dynamical model. The robustness and adaptability of real-time energy management strategy are validated through the comparison with the stationary control strategy based on initial transition probability matrix (TPM) generated from a long naturalistic driving cycle in the simulation. Results indicate that proposed method has better fuel economy than stationary one and is more effective in real-time control. PMID:28671967

Implementation of real-time energy management strategy based on reinforcement learning for hybrid electric vehicles and simulation validation.

PubMed

Kong, Zehui; Zou, Yuan; Liu, Teng

2017-01-01

To further improve the fuel economy of series hybrid electric tracked vehicles, a reinforcement learning (RL)-based real-time energy management strategy is developed in this paper. In order to utilize the statistical characteristics of online driving schedule effectively, a recursive algorithm for the transition probability matrix (TPM) of power-request is derived. The reinforcement learning (RL) is applied to calculate and update the control policy at regular time, adapting to the varying driving conditions. A facing-forward powertrain model is built in detail, including the engine-generator model, battery model and vehicle dynamical model. The robustness and adaptability of real-time energy management strategy are validated through the comparison with the stationary control strategy based on initial transition probability matrix (TPM) generated from a long naturalistic driving cycle in the simulation. Results indicate that proposed method has better fuel economy than stationary one and is more effective in real-time control.

Physically-Induced Cytoskeleton Remodeling of Cells in Three-Dimensional Culture

PubMed Central

Lee, Sheng-Lin; Nekouzadeh, Ali; Butler, Boyd; Pryse, Kenneth M.; McConnaughey, William B.; Nathan, Adam C.; Legant, Wesley R.; Schaefer, Pascal M.; Pless, Robert B.

2012-01-01

Characterizing how cells in three-dimensional (3D) environments or natural tissues respond to biophysical stimuli is a longstanding challenge in biology and tissue engineering. We demonstrate a strategy to monitor morphological and mechanical responses of contractile fibroblasts in a 3D environment. Cells responded to stretch through specific, cell-wide mechanisms involving staged retraction and reinforcement. Retraction responses occurred for all orientations of stress fibers and cellular protrusions relative to the stretch direction, while reinforcement responses, including extension of cellular processes and stress fiber formation, occurred predominantly in the stretch direction. A previously unreported role of F-actin clumps was observed, with clumps possibly acting as F-actin reservoirs for retraction and reinforcement responses during stretch. Responses were consistent with a model of cellular sensitivity to local physical cues. These findings suggest mechanisms for global actin cytoskeleton remodeling in non-muscle cells and provide insight into cellular responses important in pathologies such as fibrosis and hypertension. PMID:23300512

The size effect in corrosion greatly influences the predicted life span of concrete infrastructures.

PubMed

Angst, Ueli M; Elsener, Bernhard

2017-08-01

Forecasting the life of concrete infrastructures in corrosive environments presents a long-standing and socially relevant challenge in science and engineering. Chloride-induced corrosion of reinforcing steel in concrete is the main cause for premature degradation of concrete infrastructures worldwide. Since the middle of the past century, this challenge has been tackled by using a conceptual approach relying on a threshold chloride concentration for corrosion initiation ( C crit ). All state-of-the-art models for forecasting chloride-induced steel corrosion in concrete are based on this concept. We present an experiment that shows that C crit depends strongly on the exposed steel surface area. The smaller the tested specimen is, the higher and the more variable C crit becomes. This size effect in the ability of reinforced concrete to withstand corrosion can be explained by the local conditions at the steel-concrete interface, which exhibit pronounced spatial variability. The size effect has major implications for the future use of the common concept of C crit . It questions the applicability of laboratory results to engineering structures and the reproducibility of typically small-scale laboratory testing. Finally, we show that the weakest link theory is suitable to transform C crit from small to large dimensions, which lays the basis for taking the size effect into account in the science and engineering of forecasting the durability of infrastructures.

The size effect in corrosion greatly influences the predicted life span of concrete infrastructures

PubMed Central

Angst, Ueli M.; Elsener, Bernhard

2017-01-01

Forecasting the life of concrete infrastructures in corrosive environments presents a long-standing and socially relevant challenge in science and engineering. Chloride-induced corrosion of reinforcing steel in concrete is the main cause for premature degradation of concrete infrastructures worldwide. Since the middle of the past century, this challenge has been tackled by using a conceptual approach relying on a threshold chloride concentration for corrosion initiation (Ccrit). All state-of-the-art models for forecasting chloride-induced steel corrosion in concrete are based on this concept. We present an experiment that shows that Ccrit depends strongly on the exposed steel surface area. The smaller the tested specimen is, the higher and the more variable Ccrit becomes. This size effect in the ability of reinforced concrete to withstand corrosion can be explained by the local conditions at the steel-concrete interface, which exhibit pronounced spatial variability. The size effect has major implications for the future use of the common concept of Ccrit. It questions the applicability of laboratory results to engineering structures and the reproducibility of typically small-scale laboratory testing. Finally, we show that the weakest link theory is suitable to transform Ccrit from small to large dimensions, which lays the basis for taking the size effect into account in the science and engineering of forecasting the durability of infrastructures. PMID:28782038

Two-Dimensional Nanostructure- Reinforced Biodegradable Polymeric Nanocomposites for Bone Tissue Engineering

PubMed Central

Lalwani, Gaurav; Henslee, Allan M.; Farshid, Behzad; Lin, Liangjun; Kasper, F. Kurtis; Qin, Yi-Xian; Mikos, Antonios G.; Sitharaman, Balaji

2013-01-01

This study investigates the efficacy of two dimensional (2D) carbon and inorganic nanostructures as reinforcing agents of crosslinked composites of the biodegradable and biocompatible polymer polypropylene fumarate (PPF) as a function of nanostructure concentration. PPF composites were reinforced using various 2D nanostructures: single- and multi-walled graphene oxide nanoribbons (SWGONRs, MWGONRs), graphene oxide nanoplatelets (GONPs), and molybdenum di-sulfite nanoplatelets (MSNPs) at 0.01–0.2 weight% concentrations. Cross-linked PPF was used as the baseline control, and PPF composites reinforced with single- or multi-walled carbon nanotubes (SWCNT, MWCNT) were used as positive controls. Compression and flexural testing show a significant enhancement (i.e., compressive modulus = 35–108%, compressive yield strength = 26–93%, flexural modulus = 15–53%, and flexural yield strength = 101–262% greater than the baseline control) in the mechanical properties of the 2D-reinforced PPF nanocomposites. MSNPs nanocomposites consistently showed the highest values among the experimental or control groups in all the mechanical measurements. In general, the inorganic nanoparticle MSNPs showed a better or equivalent mechanical reinforcement compared to carbon nanomaterials, and 2-D nanostructures (GONP, MSNP) are better reinforcing agents compared to 1-D nanostructures (e.g. SWCNTs). The results also indicate that the extent of mechanical reinforcement is closely dependent on the nanostructure morphology and follows the trend nanoplatelets > nanoribbons > nanotubes. Transmission electron microscopy of the cross-linked nanocomposites indicates good dispersion of nanomaterials in the polymer matrix without the use of a surfactant. The sol-fraction analysis showed significant changes in the polymer cross-linking in the presence of MSNP (0.01–0.2 wt %) and higher loading concentrations of GONP and MWGONR (0.1–0.2 wt%). The analysis of surface area and aspect ratio of the nanostructures taken together with the above results indicates differences in nanostructure architecture (2D vs. 1D nanostructures), as well as the chemical compositions (inorganic vs. carbon nanostructures), number of functional groups, and structural defects for the 2D nanostructures maybe key properties that affect the mechanical properties of 2D nanostructure-reinforced PPF nanocomposites, and the reason for the enhanced mechanical properties compared to the controls. PMID:23405887

Physical Properties of Injection Molded Liquid Crystal Polymers and High Temperature Engineering Polymers

DTIC Science & Technology

1993-03-01

trwponsibl technmcal committee, which you may attend, It you feel that yout comments nave not received a lair hearing you shood Pake yaw views known to...34• Nonuniform part thickness "* Nonuniform cooling From these figures it can be seen that 65% mineral/ " Filler type/level glass-reinforced Fortron® PPS has

Methods of Interoperability: Moodle and WeBWork

ERIC Educational Resources Information Center

Gage, Michael E.

2017-01-01

The first requirement for an online mathematics homework engine\tis to encourage students to practice and reinforce their mathematics skills in ways that are as good or better than traditional paper homework. The use of the computer and the internet should not limit the kind or quality of the mathematics that we teach and, if possible, it should…

Maintenance of Self-Help Skill Training Programs with Non-Professional Personnel Through Incentive Systems.

ERIC Educational Resources Information Center

Patterson, Earl T.; And Others

Along with the broadening scope of behavioral programs at institutional settings has come the need for training non-professional staff to be competent behavior engineers. The two-fold purpose of this study was to explore the effectiveness of a self-scoring feedback system and two differenct schedules of reinforcement in maintaining daily training…

The Virtual Steel Sculpture--Limit State Analyses and Applications of Steel Connections

ERIC Educational Resources Information Center

Chou, Karen C.; Moaveni, Saeed; Sapp, James D.

2017-01-01

The integrity of a structural system depends on the strength of materials, shape of the individual member and the elements used to hold the members together. In most undergraduate civil engineering curricula, a structural steel and/or reinforced concrete design course is required. Usually, the main focus of these courses is on member selection…

YouTube Fridays: Student Led Development of Engineering Estimate Problems

ERIC Educational Resources Information Center

Liberatore, Matthew W.; Vestal, Charles R.; Herring, Andrew M.

2012-01-01

YouTube Fridays devotes a small fraction of class time to student-selected videos related to the course topic, e.g., thermodynamics. The students then write and solve a homework-like problem based on the events in the video. Three recent pilots involving over 300 students have developed a database of videos and questions that reinforce important…

Community, Inquiry, Leadership: Exploring Early Career Opportunities That Support STEM Teacher Growth and Sustainability

ERIC Educational Resources Information Center

Galosy, Jodie A.; Gillespie, Nicole M.

2013-01-01

Much has been written about the need for high-quality science, technology, engineering, and mathematics (STEM) teachers and their role in U.S. educational reform. In this article we provide evidence that beginning science and mathematics teachers need a blend of three mutually reinforcing learning opportunities for growth and sustainability:…

79. ARAIII. Early construction view of GCRE reactor building (ARA608) ...

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

79. ARA-III. Early construction view of GCRE reactor building (ARA-608) showing deep excavation, reinforcing steel, and forms for concrete placement for reactor and other pits. Camera facing southeast. July 22, 1958. Ineel photo no. 58-3466. Photographer: Ken Mansfield. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

17. "Concrete Bridge Over Salt River, Port Kenyon, Humboldt County, ...

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

17. "Concrete Bridge Over Salt River, Port Kenyon, Humboldt County, California, A.J. Logan, County Surveyor, H.J. Brunnier, Consulting Engineer, March 7, 1919," showing plan of bars in top flange, elevation of girder reinforcement, plan of bars in bottom flange - Salt River Bridge, Spanning Salt River at Dillon Road, Ferndale, Humboldt County, CA

Web-Based Interactive Steel Sculpture for the Google Generation

ERIC Educational Resources Information Center

Chou, Karen C.; Moaveni, Saeed

2009-01-01

In almost all the civil engineering programs in the United States, a student is required to take at least one design course in either steel or reinforced concrete. One of the topics covered in an introductory steel design course is the design of connections. Steel connections play important roles in the integrity of a structure, and many…

Joint Interdiction

DTIC Science & Technology

2016-09-09

law enforcement detachment (USCG) LEO law enforcement operations LOC line of communications MACCS Marine air command and control system MAS...enemy command and control [C2], intelligence, fires, reinforcing units, lines of communications [ LOCs ], logistics, and other operational- and tactical...enemy naval, engineering, and personnel resources to the tasks of repairing and recovering damaged equipment, facilities, and LOCs . It can draw the

Free-Operant Field Experiences: Differentially Reinforcing Successive Approximations to Behavior Analysis through a ShaperSpace

ERIC Educational Resources Information Center

Mason, Lee L.; Andrews, Alonzo; Rivera, Christopher J.; Davis, Don

2016-01-01

Over the past few years an increasing number of schools and community organizations have developed transformative learning spaces referred to as "MakerSpaces" for research and training purposes. MakerSpaces are organizations in which members sharing similar interests in science, technology, engineering, and math (STEM) gather to work on…

Engineering Education Development to Enhance Human Skill in DENSO

NASA Astrophysics Data System (ADS)

Isogai, Emiko; Nuka, Takeji

Importance of human skills such as communication or instruction capability to their staff members has recently been highlighted in a workplace, due to decreasing opportunity of face-to-face communication between supervisors and their staff, or Instruction capability through OJT (On the Job Training) . Currently, communication skills are being reinforced mainly through OJT at DENSO. Therefore, as part of supplemental support tools, DENSO has established comprehensive engineers training program on off-JT basis for developing human skills, covering from newly employeed enginners up to managerial class since 2003. This paper describes education activities and reports the results.

Complexity and robustness

PubMed Central

Carlson, J. M.; Doyle, John

2002-01-01

Highly optimized tolerance (HOT) was recently introduced as a conceptual framework to study fundamental aspects of complexity. HOT is motivated primarily by systems from biology and engineering and emphasizes, (i) highly structured, nongeneric, self-dissimilar internal configurations, and (ii) robust yet fragile external behavior. HOT claims these are the most important features of complexity and not accidents of evolution or artifices of engineering design but are inevitably intertwined and mutually reinforcing. In the spirit of this collection, our paper contrasts HOT with alternative perspectives on complexity, drawing on real-world examples and also model systems, particularly those from self-organized criticality. PMID:11875207

WORKERS FABRICATE ROOF SLABS FOR MTR BUILDING AT THE CONSTRUCTION ...

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

WORKERS FABRICATE ROOF SLABS FOR MTR BUILDING AT THE CONSTRUCTION SITE. FORMS WERE MADE OF STEEL. AFTER AN INCH OF CONCRETE HAD BEEN POURED IN THE FORM, A MAT OF REINFORCING STEEL WAS PLACED ON IT. THE REMAINDER OF THE FORM WAS FILLED, AND THE CONCRETE WAS VIBRATED, STRUCK, AND TROWELED. GROOVES AT CORNER WILL HAVE 1/4 INCH RODS WELDED INTO THE EYE OF THE STEEL MAT FOR GROUNDING. INL NEGATIVE NO. 578. Unknown Photographer, 9/1/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

Acoustics: A branch of engineering at the Universidad Austral de Chile (UACh)

NASA Astrophysics Data System (ADS)

Poblete, Victor; Arenas, Jorge P.; Sommerhoff, Jorge

2002-11-01

At the end of the 1960s, the first acousticians graduating at UACh had acquired an education in applied physics and musical arts, since there was no College of Engineering at that time. Initially, they had a (rather modest) four-year undergraduate program, and most of the faculty were not specialized teachers. The graduates from such a program received a sound engineering degree and they were skilled for jobs in the musical industry and sound reinforcement companies. In addition, they worked as sound engineers and producers. Later, because of the scientific, industrial and educational changes in Chile during the 1980s, the higher education system had massive changes that affected all of the undergraduate and graduate programs of the 61 universities in Chile. The UACh College of Engineering was officially founded in 1989. Then, acoustics as an area of expertise was included, widened and developed as an interdisciplinary subject. Currently, the undergraduate program in acoustics at UACh offers a degree in engineering sciences and a 6-year professional studies in Civil Engineering (Acoustics), having two main fields: Sound and Image, and Environment and Industry.

Reinforcement Learning Explains Conditional Cooperation and Its Moody Cousin.

PubMed

Ezaki, Takahiro; Horita, Yutaka; Takezawa, Masanori; Masuda, Naoki

2016-07-01

Direct reciprocity, or repeated interaction, is a main mechanism to sustain cooperation under social dilemmas involving two individuals. For larger groups and networks, which are probably more relevant to understanding and engineering our society, experiments employing repeated multiplayer social dilemma games have suggested that humans often show conditional cooperation behavior and its moody variant. Mechanisms underlying these behaviors largely remain unclear. Here we provide a proximate account for this behavior by showing that individuals adopting a type of reinforcement learning, called aspiration learning, phenomenologically behave as conditional cooperator. By definition, individuals are satisfied if and only if the obtained payoff is larger than a fixed aspiration level. They reinforce actions that have resulted in satisfactory outcomes and anti-reinforce those yielding unsatisfactory outcomes. The results obtained in the present study are general in that they explain extant experimental results obtained for both so-called moody and non-moody conditional cooperation, prisoner's dilemma and public goods games, and well-mixed groups and networks. Different from the previous theory, individuals are assumed to have no access to information about what other individuals are doing such that they cannot explicitly use conditional cooperation rules. In this sense, myopic aspiration learning in which the unconditional propensity of cooperation is modulated in every discrete time step explains conditional behavior of humans. Aspiration learners showing (moody) conditional cooperation obeyed a noisy GRIM-like strategy. This is different from the Pavlov, a reinforcement learning strategy promoting mutual cooperation in two-player situations.

Development of a metal-clad advanced composite shear web design concept

NASA Technical Reports Server (NTRS)

Laakso, J. H.

1974-01-01

An advanced composite web concept was developed for potential application to the Space Shuttle Orbiter main engine thrust structure. The program consisted of design synthesis, analysis, detail design, element testing, and large scale component testing. A concept was sought that offered significant weight saving by the use of Boron/Epoxy (B/E) reinforced titanium plate structure. The desired concept was one that was practical and that utilized metal to efficiently improve structural reliability. The resulting development of a unique titanium-clad B/E shear web design concept is described. Three large scale components were fabricated and tested to demonstrate the performance of the concept: a titanium-clad plus or minus 45 deg B/E web laminate stiffened with vertical B/E reinforced aluminum stiffeners.

Experimental and theoretical study of the operation of longitudinal sidewalls in reinforced concrete superstructures

NASA Astrophysics Data System (ADS)

Bokarev, Sergey; Efimov, Stefan

2017-11-01

In the present article, we report results of a laboratory experimental study of reinforced-concrete superstructure fragments with extended longitudinal boxing sidewalls. The study included laboratory tests and numerical experiments performed using a finite element model of fragments generated in specialized simulation software. The distribution of horizontal pressures over the height of longitudinal boxing sidewalls, the dependence of the bending moment in the root section of the sidewalls on the ballast-bed thickness under sleepers, and some other characteristics were examined. The results of the experimental and theoretical study have shown a good convergence of obtained data to each other and to the data obtained by an improved engineering calculation procedure proposed by the present authors.

Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection.

PubMed

Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

2016-12-16

In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection

PubMed Central

Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

2016-01-01

In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering. PMID:27999245

Homogenization Models for Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Muc, A.; Jamróz, M.

2004-03-01

Two homogenization models for evaluating Young's modulus of nanocomposites reinforced with single-walled and multi-walled carbon nanotubes are presented. The first model is based on a physical description taking into account the interatomic interaction and nanotube geometry. The elementary cell, here a nanotube with a surrounding resin layer, is treated as a homogeneous body — a material continuum. The second model, similar to a phenomenological engineering one, is obtained by combining the law of mixture with the Cox mechanical model. This model describes the stress distribution along stretched short fibers surrounded by a resin matrix. The similarities between composite materials reinforced with short fibers and nanotubes are elucidated. The results obtained are compared with those for classical microcomposites to demonstrate the advantages and disadvantages of both the composite materials.

A thermoplastic polyimidesulfone

NASA Technical Reports Server (NTRS)

St.clair, T. L.; Yamaki, D. A.

1982-01-01

A polymer system has been prepared which has the excellent thermoplastic properties generally associated with polysulfones, and the solvent resistance and thermal stability of aromatic polyimides. This material, with improved processability over the base polyimide, can be processed in the 260-325 C range in such a manner as to yield high quality, tough unfilled moldings; strong, high-temperature-resistant adhesive bonds; and well consolidated, graphite-fiber-reinforced moldings (composities). The unfilled moldings have physical properties that are similar to aromatic polysulfones which demonstrates the potential as an engineering thermoplastic. The adhesive bonds exhibit excellent retention of initial strength levels even after thermal aging for 5000 hours at 232 C. The graphite-fiber-reinforced moldings have mechanical properties which makes this polymer attractive for the fabrication of structural composites.

Composite structural materials. [fiber reinforced composites for aircraft structures

NASA Technical Reports Server (NTRS)

Ansell, G. S.; Loewy, R. G.; Wiberly, S. E.

1981-01-01

Physical properties of fiber reinforced composites; structural concepts and analysis; manufacturing; reliability; and life prediction are subjects of research conducted to determine the long term integrity of composite aircraft structures under conditions pertinent to service use. Progress is reported in (1) characterizing homogeneity in composite materials; (2) developing methods for analyzing composite materials; (3) studying fatigue in composite materials; (4) determining the temperature and moisture effects on the mechanical properties of laminates; (5) numerically analyzing moisture effects; (6) numerically analyzing the micromechanics of composite fracture; (7) constructing the 727 elevator attachment rib; (8) developing the L-1011 engine drag strut (CAPCOMP 2 program); (9) analyzing mechanical joints in composites; (10) developing computer software; and (11) processing science and technology, with emphasis on the sailplane project.

Hydroxyapatite reinforced collagen scaffolds with improved architecture and mechanical properties.

PubMed

Kane, Robert J; Weiss-Bilka, Holly E; Meagher, Matthew J; Liu, Yongxing; Gargac, Joshua A; Niebur, Glen L; Wagner, Diane R; Roeder, Ryan K

2015-04-01

Hydroxyapatite (HA) reinforced collagen scaffolds have shown promise for synthetic bone graft substitutes and tissue engineering scaffolds. Freeze-dried HA-collagen scaffolds are readily fabricated and have exhibited osteogenicity in vivo, but are limited by an inherent scaffold architecture that results in a relatively small pore size and weak mechanical properties. In order to overcome these limitations, HA-collagen scaffolds were prepared by compression molding HA reinforcements and paraffin microspheres within a suspension of concentrated collagen fibrils (∼ 180 mg/mL), cross-linking the collagen matrix, and leaching the paraffin porogen. HA-collagen scaffolds exhibited an architecture with high porosity (85-90%), interconnected pores ∼ 300-400 μm in size, and struts ∼ 3-100 μm in thickness containing 0-80 vol% HA whisker or powder reinforcements. HA reinforcement enabled a compressive modulus of up to ∼ 1 MPa, which was an order of magnitude greater than unreinforced collagen scaffolds. The compressive modulus was also at least one order of magnitude greater than comparable freeze-dried HA-collagen scaffolds and two orders of magnitude greater than absorbable collagen sponges used clinically. Moreover, scaffolds reinforced with up to 60 vol% HA exhibited fully recoverable elastic deformation upon loading to 50% compressive strain for at least 100,000 cycles. Thus, the scaffold mechanical properties were well-suited for surgical handling, fixation, and bearing osteogenic loads during bone regeneration. The scaffold architecture, permeability, and composition were shown to be conducive to the infiltration and differentiation of adipose-derive stromal cells in vitro. Acellular scaffolds were demonstrated to induce angiogenesis and osteogenesis after subcutaneous ectopic implantation by recruiting endogenous cell populations, suggesting that the scaffolds were osteoinductive. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Dispersion fraction enhances cellular growth of carbon nanotube and aluminum oxide reinforced ultrahigh molecular weight polyethylene biocomposites.

PubMed

Patel, Anup Kumar; Balani, Kantesh

2015-01-01

Ultrahigh molecular weight polyethylene (UHMWPE) is widely used as bone-replacement material for articulating surfaces due to its excellent wear resistance and low coefficient of friction. But, the wear debris, generated during abrasion between mating surfaces, leads to aseptic loosening of implants. Thus, various reinforcing agents are generally utilized, which may alter the surface and biological properties of UHMWPE. In the current work, the cellular response of compression molded UHMWPE upon reinforcement of bioactive multiwalled carbon nanotubes (MWCNTs) and bioinert aluminum oxide (Al2O3) is investigated. The phase retention and stability were observed using X-ray diffraction, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The reinforcement of MWCNTs and Al2O3 has shown to alter the wettability (from contact angle of ~88°±2° to ~118°±4°) and surface energy (from ~23.20 to ~17.75 mN/m) of composites with respect to UHMWPE, without eliciting any adverse effect on cytocompatibility for the L929 mouse fibroblast cell line. Interestingly, the cellular growth of the L929 mouse fibroblast cell line is observed to be dominated by the dispersion fraction of surface free energy (SFE). After 48 h of incubation period, a decrease in metabolic activity of MWCNT-Al2O3 reinforced composites is attributed to apatite formation that reduces the dispersion fraction of surface energy. The mineralized apatite during incubation was confirmed and quantified by energy dispersive spectroscopy and X-ray diffraction respectively. Thus, the dispersion fraction of surface free energy can be engineered to play an important role in achieving enhanced metabolic activity of the MWCNT-Al2O3 reinforced UHMWPE biopolymer composites. Copyright © 2014 Elsevier B.V. All rights reserved.

Parameter optimization and evaluation of mechanical and thermal properties of nanographene reinforced Al 6060 surface composite using FSP

NASA Astrophysics Data System (ADS)

Kalyanamanohar, V.; Appalachari, D. Gireesh Chandra

2018-04-01

Friction stir processing (FSP) is emerging as a promising technique for making surface composites. FSP can improve surface properties such as hardness, strength, ductility, corrosion resistance, fatigue life and formability without affecting the bulk properties of the material. The literatures reported that FSP can produces very fine equiaxed and homogeneous grain structure for different Al alloys. Al 6060 is heat treatable alloy which has high thermal and electrical properties than remaining Al alloys. Al 6060 is being used where high rate of heat exchange is needed i.e. engine cylinders, heat exchangers etc. As derived from the carbon materials, like graphene and CNTs dissipates heat rapidly that improves the life of the engine cylinders and heat exchangers. In this work, nanographene is reinforced in the Al 6060 using friction stir processing at different rotational speeds, traverse speeds, and at constant load and tool tilt angle. After processed, the effect of process parameters on microstructure of the surface composite was investigated. The SEM studies shows that the FSP produces very fine and homogenous grain structure and it is observed that smaller grain size structure is obtained at lower traverse speed and higher rotational speeds. Significant improvement in ultimate tensile strength(22.9%) and hardness (22.44%) when compared friction stir processed plate at 1400 rotational speed and 20mm/min traverse speed with base Al 6060 plate. Coefficient of thermal expansion test of nanographene reinforced Al 6060 shows 7.33% decrease in its coefficient of thermal expansion as graphene has tendency to reduce the anisotropic nature.

MWCNTs/P(St-co-GMA) composite nanofibers of engineered interface chemistry for epoxy matrix nanocomposites.

PubMed

Özden-Yenigün, Elif; Menceloğlu, Yusuf Z; Papila, Melih

2012-02-01

Strengthened nanofiber-reinforced epoxy matrix composites are demonstrated by engineering composite electrospun fibers of multi-walled carbon nanotubes (MWCNTs) and reactive P(St-co-GMA). MWCNTs are incorporated into surface-modified, reactive P(St-co-GMA) nanofibers by electrospinning; functionalization of these MWCNT/P(St-co-GMA) composite nanofibers with epoxide moieties facilitates bonding at the interface of the cross-linked fibers and the epoxy matrix, effectively reinforcing and toughening the epoxy resin. Rheological properties are determined and thermodynamic stabilization is demonstrated for MWCNTs in the P(St-co-GMA)-DMF polymer solution. Homogeneity and uniformity of the fiber formation within the electrospun mats are achieved at polymer concentration of 30 wt %. Results show that the MWCNT fraction decreases the polymer solution viscosity, yielding a narrower fiber diameter. The fiber diameter drops from an average of 630 nm to 460 nm, as the MWCNTs wt fraction (1, 1.5, and 2%) is increased. The electrospun nanofibers of the MWCNTs/P(St-co-GMA) composite are also embedded into an epoxy resin to investigate their reinforcing abilities. A significant increase in the mechanical response is observed, up to >20% in flexural modulus, when compared to neat epoxy, despite a very low composite fiber weight fraction (at about 0.2% by a single-layer fibrous mat). The increase is attributed to the combined effect of the two factors the inherent strength of the well-dispersed MWCNTs and the surface chemistry of the electrospun fibers that have been modified with epoxide to enable cross-linking between the polymer matrix and the nanofibers.

Development of a reinforced electrochemically aligned collagen bioscaffold for tendon tissue engineering applications

NASA Astrophysics Data System (ADS)

Uquillas Paredes, Jorge Alfredo

Type-I collagen is a promising biomaterial that can be used to synthesize bioscaffolds as a strategy to regenerate and repair damaged tendons. The existing in vitro prepared collagen bioscaffolds are in the form of gels, foams, or extruded fibers. These bioscaffolds readily present sites for attachment of biological factors and cells; however, they have extremely poor biomechanical properties in comparison to the properties of native tendons. The biomechanical function of type-I collagen bioscaffolds needs to be elevated to the level of natural tissues for this biomaterial to replace mechanically challenged tendons in a functionally meaningful way. The overall goal of this dissertation is to develop a reinforced electrochemically aligned collagenous bioscaffold for applications in tendon tissue engineering. The bioscaffold is synthesized by a unique electrochemical process via isoelectric focusing (IEF) to attain a very high degree of molecular alignment and packing density. This dissertation presents progress made on four aims: A) development of simple and descriptive electrochemical theory via the mathematical model of IEF and the forces acting on collagen alignment under an electric field; B) optimization of the post-alignment PBS treatment step to achieve d- banding pattern in uncrosslinked electrochemically aligned collagen (ELAC) bioscaffolds; C) optimization of the best crosslinking protocol to produce the strongest possible ELAC biomaterial with excellent cellular compatibility; and D) in vivo evaluation of the biocompatibility and biodegradability properties of electronically aligned collagen bioscaffolds. The results of this dissertation provide strong evidence showing that reinforced ELAC bioscaffolds could be used clinically in the future to repair damaged tendons.

Acoustic emission monitoring of concrete columns and beams strengthened with fiber reinforced polymer sheets

NASA Astrophysics Data System (ADS)

Ma, Gao; Li, Hui; Zhou, Wensong; Xian, Guijun

2012-04-01

Acoustic emission (AE) technique is an effective method in the nondestructive testing (NDT) field of civil engineering. During the last two decades, Fiber reinforced polymer (FRP) has been widely used in repairing and strengthening concrete structures. The damage state of FRP strengthened concrete structures has become an important issue during the service period of the structure and it is a meaningful work to use AE technique as a nondestructive method to assess its damage state. The present study reports AE monitoring results of axial compression tests carried on basalt fiber reinforced polymer (BFRP) confined concrete columns and three-point-bending tests carried on BFRP reinforced concrete beams. AE parameters analysis was firstly utilized to give preliminary results of the concrete fracture process of these specimens. It was found that cumulative AE events can reflect the fracture development trend of both BFRP confined concrete columns and BFRP strengthened concrete beams and AE events had an abrupt increase at the point of BFRP breakage. Then the fracture process of BFRP confined concrete columns and BFRP strengthened concrete beams was studied through RA value-average frequency analysis. The RA value-average frequency tendencies of BFRP confined concrete were found different from that of BFRP strengthened concrete beams. The variation tendency of concrete crack patterns during the loading process was revealed.

Liquid Coatings for Reducing Corrosion of Steel in Concrete

NASA Technical Reports Server (NTRS)

MacDowell, Louis G.; Curran, Joseph

2003-01-01

Inorganic coating materials are being developed to slow or stop corrosion of reinforcing steel members inside concrete structures. It is much simpler and easier to use these coating materials than it is to use conventional corrosion-inhibiting systems based on impressed electric currents. Unlike impressed electrical corrosion-inhibiting systems, these coatings do not require continuous consumption of electrical power and maintenance of power-supply equipment. Whereas some conventional systems involve the use of expensive arc-spray equipment to apply the metallic zinc used as the sacrificial anode material, the developmental coatings can be applied by use of ordinary paint sprayers. A coating material of the type under development is formulated as a liquid containing blended metallic particles and/or moisture-attracting compounds. The liquid mixture is sprayed onto a concrete structure. Experiments have shown that even though such a coat resides on the exterior surface, it generates a protective galvanic current that flows to the interior reinforcing steel members. By effectively transferring the corrosion process from the steel reinforcement to the exterior coating, the protective current slows or stops corrosion of the embedded steel. Specific formulations have been found to meet depolarization criteria of the National Association of Corrosion Engineers (NACE) for complete protection of steel reinforcing bars ("rebar") embedded in concrete.

Corrosion and Wear Response of Oxide-Reinforced Nickel Composite Coatings

NASA Astrophysics Data System (ADS)

Tirlapur, Pradeep; Muniprakash, M.; Srivastava, Meenu

2016-07-01

Various grades of fuels are used in automobiles, as a result the engine components are continuously subjected to simultaneous action of corrosion and wear. Ni-SiC composite coating is the most widely investigated and commercialized wear-resistant coating in the automotive industry. However, this coating cannot be used at temperatures above 450 °C due to the tendency of SiC to react with Ni and form brittle silicides. An alternate approach is to use oxide-reinforced coatings. In the present study, zirconia, ZrO2 and, yttria-stabilized zirconia, YSZ-reinforced Ni composite coatings have been developed by electrodeposition method. It was observed from the microhardness studies that there is no significant difference in the values for Ni-SiC and Ni-ZrO2 coatings. The corrosion behavior was evaluated using polarization and electrochemical impedance studies. The studies showed that oxide particle-reinforced Ni coatings possessed better corrosion resistance due to their lower corrosion current density, I corr. Tribo-corrosion studies were carried out to understand the synergistic effect of wear and corrosion on the performance of Ni-based composite coatings in 0.5 M Na2SO4. Among various composite coatings, Ni-YSZ exhibited less material loss thereby showing better tribo-corrosion behavior.

Tungsten Disulfide Nanotubes Reinforced Biodegradable Polymers for Bone Tissue Engineering

PubMed Central

Lalwani, Gaurav; Henslee, Allan M.; Farshid, Behzad; Parmar, Priyanka; Lin, Liangjun; Qin, Yi-Xian; Kasper, F. Kurtis; Mikos, Antonios G.; Sitharaman, Balaji

2013-01-01

In this study, we have investigated the efficacy of inorganic nanotubes as reinforcing agents to improve the mechanical properties of poly(propylene fumarate) (PPF) composites as a function of nanomaterial loading concentration (0.01-0.2 wt%). Tungsten disulfide nanotubes (WSNTs) were used as reinforcing agents in the experimental groups. Single- and multi- walled carbon nanotubes (SWCNTs and MWCNTs) were used as positive controls, and crosslinked PPF composites were used as baseline control. Mechanical testing (compression and three-point bending) shows a significant enhancement (up to 28-190%) in the mechanical properties (compressive modulus, compressive yield strength, flexural modulus, and flexural yield strength) of WSNT reinforced PPF nanocomposites compared to the baseline control. In comparison to positive controls, at various concentrations, significant improvements in the mechanical properties of WSNT nanocomposites were also observed. In general, the inorganic nanotubes (WSNTs) showed a better (up to 127%) or equivalent mechanical reinforcement compared to carbon nanotubes (SWCNTs and MWCNTs). Sol fraction analysis showed significant increases in the crosslinking density of PPF in the presence of WSNTs (0.01-0.2 wt%). Transmission electron microscopy (TEM) analysis on thin sections of crosslinked nanocomposites showed the presence of WSNTs as individual nanotubes in the PPF matrix, whereas SWCNTs and MWCNTs existed as micron sized aggregates. The trend in the surface area of nanostructures obtained by BET surface area analysis was SWCNTs > MWCNTs > WSNTs. The BET surface area analysis, TEM analysis, and sol fraction analysis results taken together suggest that chemical composition (inorganic vs. carbon nanomaterials), presence of functional groups (such as sulfide and oxysulfide), and individual dispersion of the nanomaterials in the polymer matrix (absence of aggregation of the reinforcing agent) are the key parameters affecting the mechanical properties of nanostructure-reinforced PPF composites, and the reason for the observed increases in the mechanical properties compared to the baseline and positive controls. PMID:23727293

Micro-mechanics modelling of smart materials

NASA Astrophysics Data System (ADS)

Shah, Syed Asim Ali

Metal Matrix ceramic-reinforced composites are rapidly becoming strong candidates as structural materials for many high temperature and engineering applications. Metal matrix composites (MMC) combine the ductile properties of the matrix with a brittle phase of the reinforcement, leading to high stiffness and strength with a reduction in structural weight. The main objective of using a metal matrix composite system is to increase service temperature or improve specific mechanical properties of structural components by replacing existing super alloys.The purpose of the study is to investigate, develop and implement second phase reinforcement alloy strengthening empirical model with SiCp reinforced A359 aluminium alloy composites on the particle-matrix interface and the overall mechanical properties of the material.To predict the interfacial fracture strength of aluminium, in the presence of silicon segregation, an empirical model has been modified. This model considers the interfacial energy caused by segregation of impurities at the interface and uses Griffith crack type arguments to predict the formation energies of impurities at the interface. Based on this, model simulations were conducted at nano scale specifically at the interface and the interfacial strengthening behaviour of reinforced aluminium alloy system was expressed in terms of elastic modulus.The numerical model shows success in making prediction possible of trends in relation to segregation and interfacial fracture strength behaviour in SiC particle-reinforced aluminium matrix composites. The simulation models using various micro scale modelling techniques to the aluminum alloy matrix composite, strengthenedwith varying amounts of silicon carbide particulate were done to predict the material state at critical points with properties of Al-SiC which had been heat treated.In this study an algorithm is developed to model a hard ceramic particle in a soft matrix with a clear distinct interface and a strain based relationship has been proposed for the strengthening behaviour of the MMC at the interface rather than stress based, by successfully completing the numerical modelling of particulate reinforced metal matrix composites.

Implementation of a Space Communications Cognitive Engine

NASA Technical Reports Server (NTRS)

Hackett, Timothy M.; Bilen, Sven G.; Ferreira, Paulo Victor R.; Wyglinski, Alexander M.; Reinhart, Richard C.

2017-01-01

Although communications-based cognitive engines have been proposed, very few have been implemented in a full system, especially in a space communications system. In this paper, we detail the implementation of a multi-objective reinforcement-learning algorithm and deep artificial neural networks for the use as a radio-resource-allocation controller. The modular software architecture presented encourages re-use and easy modification for trying different algorithms. Various trade studies involved with the system implementation and integration are discussed. These include the choice of software libraries that provide platform flexibility and promote reusability, choices regarding the deployment of this cognitive engine within a system architecture using the DVB-S2 standard and commercial hardware, and constraints placed on the cognitive engine caused by real-world radio constraints. The implemented radio-resource allocation-management controller was then integrated with the larger spaceground system developed by NASA Glenn Research Center (GRC).

Ablative material testing for low-pressure, low-cost rocket engines

NASA Technical Reports Server (NTRS)

Richter, G. Paul; Smith, Timothy D.

1995-01-01

The results of an experimental evaluation of ablative materials suitable for the production of light weight, low cost rocket engine combustion chambers and nozzles are presented. Ten individual specimens of four different compositions of silica cloth-reinforced phenolic resin materials were evaluated for comparative erosion in a subscale rocket engine combustion chamber. Gaseous hydrogen and gaseous oxygen were used as propellants, operating at a nominal chamber pressure of 1138 kPa (165 psi) and a nominal mixture ratio (O/F) of 3.3. These conditions were used to thermally simulate operation with RP-1 and liquid oxygen, and achieved a specimen throat gas temperature of approximately 2456 K (4420 R). Two high-density composition materials exhibited high erosion resistance, while two low-density compositions exhibited approximately 6-75 times lower average erosion resistance. The results compare favorably with previous testing by NASA and provide adequate data for selection of ablatives for low pressure, low cost rocket engines.

A Center for Extraterrestrial Engineering and Construction (CETEC)

NASA Technical Reports Server (NTRS)

Leigh, Gerald G.

1992-01-01

A group of knowledgeable scientists and engineers in New Mexico has recognized the need for such a testing capability and has proposed a project to evelop an extraterrestrial surface simulation facility. A group of universities, national laboratories, and private industrial firms is proposing to establish a Center for Extraterrestrial Engineering and Construction (CETEC) and to develop large extraterrestrial surface simulation facilities in which this needed testing can be realistically performed. The CETEC is envisioned to be both a center of knowledge and data regarding engineering, construction, mining, and material process operations on extraterrestrial bodies and a set of extraterrestrial surface simulation facilities. The primary CETEC facility is proposed to be a large domed building made of steel reinforced concrete with more than one acre of test floor area covered with several feet of simulated lunar soil and dust. Various aspects of the project are presented in viewgraph form.

PBL and CDIO: complementary models for engineering education development

NASA Astrophysics Data System (ADS)

Edström, Kristina; Kolmos, Anette

2014-09-01

This paper compares two models for reforming engineering education, problem/project-based learning (PBL), and conceive-design-implement-operate (CDIO), identifying and explaining similarities and differences. PBL and CDIO are defined and contrasted in terms of their history, community, definitions, curriculum design, relation to disciplines, engineering projects, and change strategy. The structured comparison is intended as an introduction for learning about any of these models. It also invites reflection to support the understanding and evolution of PBL and CDIO, and indicates specifically what the communities can learn from each other. It is noted that while the two approaches share many underlying values, they only partially overlap as strategies for educational reform. The conclusions are that practitioners have much to learn from each other's experiences through a dialogue between the communities, and that PBL and CDIO can play compatible and mutually reinforcing roles, and thus can be fruitfully combined to reform engineering education.

High-Performance SiC/SiC Ceramic Composite Systems Developed for 1315 C (2400 F) Engine Components

NASA Technical Reports Server (NTRS)

DiCarlo, James A.; Yun, Hee Mann; Morscher, Gregory N.; Bhatt, Ramakrishna T.

2004-01-01

As structural materials for hot-section components in advanced aerospace and land-based gas turbine engines, silicon carbide (SiC) ceramic matrix composites reinforced by high performance SiC fibers offer a variety of performance advantages over current bill-of-materials, such as nickel-based superalloys. These advantages are based on the SiC/SiC composites displaying higher temperature capability for a given structural load, lower density (approximately 30- to 50-percent metal density), and lower thermal expansion. These properties should, in turn, result in many important engine benefits, such as reduced component cooling air requirements, simpler component design, reduced support structure weight, improved fuel efficiency, reduced emissions, higher blade frequencies, reduced blade clearances, and higher thrust. Under the NASA Ultra-Efficient Engine Technology (UEET) Project, much progress has been made at the NASA Glenn Research Center in identifying and optimizing two highperformance SiC/SiC composite systems. The table compares typical properties of oxide/oxide panels and SiC/SiC panels formed by the random stacking of balanced 0 degrees/90 degrees fabric pieces reinforced by the indicated fiber types. The Glenn SiC/SiC systems A and B (shaded area of the table) were reinforced by the Sylramic-iBN SiC fiber, which was produced at Glenn by thermal treatment of the commercial Sylramic SiC fiber (Dow Corning, Midland, MI; ref. 2). The treatment process (1) removes boron from the Sylramic fiber, thereby improving fiber creep, rupture, and oxidation resistance and (2) allows the boron to react with nitrogen to form a thin in situ grown BN coating on the fiber surface, thereby providing an oxidation-resistant buffer layer between contacting fibers in the fabric and the final composite. The fabric stacks for all SiC/SiC panels were provided to GE Power Systems Composites for chemical vapor infiltration of Glenn designed BN fiber coatings and conventional SiC matrices. Composite panels with system B were heat treated at Glenn, and the pores that remained open were filled by silicon melt infiltration (MI). Panels with system A and the other SiC/SiC systems were not heat treated, and remaining open pores in these systems were filled with SiC slurry and silicon MI.

Ceramics for engines

NASA Technical Reports Server (NTRS)

Kiser, James D.; Levine, Stanley R.; Dicarlo, James A.

1987-01-01

Structural ceramics were under nearly continuous development for various heat engine applications since the early 1970s. These efforts were sustained by the properties that ceramics offer in the areas of high-temperature strength, environmental resistance, and low density and the large benefits in system efficiency and performance that can result. The promise of ceramics was not realized because their brittle nature results in high sensitivity to microscopic flaws and catastrophic fracture behavior. This translated into low reliability for ceramic components and thus limited their application in engines. For structural ceramics to successfully make inroads into the terrestrial heat engine market requires further advances in low cost, net shape fabrication of high reliability components, and improvements in properties such as toughness, and strength. These advances will lead to very limited use of ceramics in noncritical applications in aerospace engines. For critical aerospace applications, an additional requirement is that the components display markedly improved toughness and noncatastrophic or graceful fracture. Thus the major emphasis is on fiber-reinforced ceramics.

TexMi: Development of Tissue-Engineered Textile-Reinforced Mitral Valve Prosthesis

PubMed Central

Moreira, Ricardo; Gesche, Valentine N.; Hurtado-Aguilar, Luis G.; Schmitz-Rode, Thomas; Frese, Julia

2014-01-01

Mitral valve regurgitation together with aortic stenosis is the most common valvular heart disease in Europe and North America. Mechanical and biological prostheses available for mitral valve replacement have significant limitations such as the need of a long-term anticoagulation therapy and failure by calcifications. Both types are unable to remodel, self-repair, and adapt to the changing hemodynamic conditions. Moreover, they are mostly designed for the aortic position and do not reproduce the native annular-ventricular continuity, resulting in suboptimal hemodynamics, limited durability, and gradually decreasing ventricular pumping efficiency. A tissue-engineered heart valve specifically designed for the mitral position has the potential to overcome the limitations of the commercially available substitutes. For this purpose, we developed the TexMi, a living textile-reinforced mitral valve, which recapitulates the key elements of the native one: annulus, asymmetric leaflets (anterior and posterior), and chordae tendineae to maintain the native annular-ventricular continuity. The tissue-engineered valve is based on a composite scaffold consisting of the fibrin gel as a cell carrier and a textile tubular structure with the twofold task of defining the gross three-dimensional (3D) geometry of the valve and conferring mechanical stability. The TexMi valves were molded with ovine umbilical vein cells and stimulated under dynamic conditions for 21 days in a custom-made bioreactor. Histological and immunohistological stainings showed remarkable tissue development with abundant aligned collagen fibers and elastin deposition. No cell-mediated tissue contraction occurred. This study presents the proof-of-principle for the realization of a tissue-engineered mitral valve with a simple and reliable injection molding process readily adaptable to the patient's anatomy and pathological situation by producing a patient-specific rapid prototyped mold. PMID:24665896

Reinforcement-learning-based dual-control methodology for complex nonlinear discrete-time systems with application to spark engine EGR operation.

PubMed

Shih, Peter; Kaul, Brian C; Jagannathan, S; Drallmeier, James A

2008-08-01

A novel reinforcement-learning-based dual-control methodology adaptive neural network (NN) controller is developed to deliver a desired tracking performance for a class of complex feedback nonlinear discrete-time systems, which consists of a second-order nonlinear discrete-time system in nonstrict feedback form and an affine nonlinear discrete-time system, in the presence of bounded and unknown disturbances. For example, the exhaust gas recirculation (EGR) operation of a spark ignition (SI) engine is modeled by using such a complex nonlinear discrete-time system. A dual-controller approach is undertaken where primary adaptive critic NN controller is designed for the nonstrict feedback nonlinear discrete-time system whereas the secondary one for the affine nonlinear discrete-time system but the controllers together offer the desired performance. The primary adaptive critic NN controller includes an NN observer for estimating the states and output, an NN critic, and two action NNs for generating virtual control and actual control inputs for the nonstrict feedback nonlinear discrete-time system, whereas an additional critic NN and an action NN are included for the affine nonlinear discrete-time system by assuming the state availability. All NN weights adapt online towards minimization of a certain performance index, utilizing gradient-descent-based rule. Using Lyapunov theory, the uniformly ultimate boundedness (UUB) of the closed-loop tracking error, weight estimates, and observer estimates are shown. The adaptive critic NN controller performance is evaluated on an SI engine operating with high EGR levels where the controller objective is to reduce cyclic dispersion in heat release while minimizing fuel intake. Simulation and experimental results indicate that engine out emissions drop significantly at 20% EGR due to reduction in dispersion in heat release thus verifying the dual-control approach.

A Service Learning Project on Aluminum Recycling--Developing Soft Skills in a Material and Energy Balances Course

ERIC Educational Resources Information Center

West, Christy Wheeler

2017-01-01

This paper describes a project carried out in a sophomore chemical engineering course, in which students studied the energetic differences between refining and recycling aluminum. They worked in teams to prepare a presentation about the importance of aluminum recycling to a lay audience. The project reinforced classroom learning and provided an…

Does Applied STEM Course Taking Link to STEM Outcomes for High School Students with Learning Disabilities?

ERIC Educational Resources Information Center

Gottfried, Michael A.; Sublett, Cameron

2018-01-01

Over the most recent two decades, federal policy has urged high schools to embed applied science, technology, engineering, and mathematics (STEM) courses into the curriculum to reinforce concepts learned in traditional math and science classes as well as to motivate students' interests and long-term pursuits in STEM areas. While prior research has…

The Relationships among High School STEM Learning Experiences and Students' Intent to Declare and Declaration of a STEM Major in College

ERIC Educational Resources Information Center

Bottia, Martha Cecilia; Stearns, Elizabeth; Mickelson, Roslyn Arlin; Moller, Stephanie; Parker, Ashley Dawn

2015-01-01

Background/Context: Schools are integral to augmenting and diversifying the science, technology, engineering, and mathematics (STEM) workforce. This is because K-12 schools can inspire and reinforce students' interest in STEM, in addition to academically preparing them to pursue a STEM career. Previous literature emphasizes the importance of…

State of the Art Reinforcement for Concrete Bridge Decks

DTIC Science & Technology

2009-02-01

Microcomposite Martensitic Ferretic Steel (MMFX 2) • Initial proprietary technology developed at the University of California Berkeley by...Center US Army Corps of Engineers Microcomposite Steel Microcomposite Steels , Packet Lath Martensite Dislocated laths of martensite enveloped by... steel cladding with carbon steel core • Patented “green” process bonds stainless steel to carbon steel • Optimizes stainless steel’s very high

Fibre-reinforced hydrogels for tissue engineering

NASA Astrophysics Data System (ADS)

Waters, Sarah; Byrne, Helen; Chen, Mike; Dias Castilho, Miguel; Kimpton, Laura; Please, Colin; Whiteley, Jonathan

2017-11-01

Tissue engineers aim to grow replacement tissues in vitro to replace those in the body that have been damaged through age, trauma or disease. One approach is to seed cells within a scaffold consisting of an interconnected 3D-printed lattice of polymer fibres, cast in a hydrogel, and subject the construct (cell-seeded scaffold) to an applied load in a bioreactor. A key question is to understand how this applied load is distributed throughout the construct to the mechanosensitive cells. To address this, we exploit the disparate length scales (small inter-fibre spacing compared with construct dimensions). The fibres are treated as a linear elastic material and the hydrogel as a poroelastic material. We employ homogenisation theory to derive equations governing the material properties of a periodic, elastic-poroelastic composite. To validate the mobel, model solutions are compared to experimental data describing the unconfined compression of the fibre-reinforced hydrogels. The model is used to derive the bulk mechanical properties of a cylindrical construct of the composite material for a range of fibre spacings, and the local mechanical environment experienced by cells embedded within the construct is determined. Funded by the European Union Seventh Framework Programme (FP7/2007-2013).

Using a Search Engine-Based Mutually Reinforcing Approach to Assess the Semantic Relatedness of Biomedical Terms

PubMed Central

Hsu, Yi-Yu; Chen, Hung-Yu; Kao, Hung-Yu

2013-01-01

Background Determining the semantic relatedness of two biomedical terms is an important task for many text-mining applications in the biomedical field. Previous studies, such as those using ontology-based and corpus-based approaches, measured semantic relatedness by using information from the structure of biomedical literature, but these methods are limited by the small size of training resources. To increase the size of training datasets, the outputs of search engines have been used extensively to analyze the lexical patterns of biomedical terms. Methodology/Principal Findings In this work, we propose the Mutually Reinforcing Lexical Pattern Ranking (ReLPR) algorithm for learning and exploring the lexical patterns of synonym pairs in biomedical text. ReLPR employs lexical patterns and their pattern containers to assess the semantic relatedness of biomedical terms. By combining sentence structures and the linking activities between containers and lexical patterns, our algorithm can explore the correlation between two biomedical terms. Conclusions/Significance The average correlation coefficient of the ReLPR algorithm was 0.82 for various datasets. The results of the ReLPR algorithm were significantly superior to those of previous methods. PMID:24348899

How Can Nanotechnology Help to Repair the Body? Advances in Cardiac, Skin, Bone, Cartilage and Nerve Tissue Regeneration

PubMed Central

Perán, Macarena; García, María Angel; Lopez-Ruiz, Elena; Jiménez, Gema; Marchal, Juan Antonio

2013-01-01

Nanotechnologists have become involved in regenerative medicine via creation of biomaterials and nanostructures with potential clinical implications. Their aim is to develop systems that can mimic, reinforce or even create in vivo tissue repair strategies. In fact, in the last decade, important advances in the field of tissue engineering, cell therapy and cell delivery have already been achieved. In this review, we will delve into the latest research advances and discuss whether cell and/or tissue repair devices are a possibility. Focusing on the application of nanotechnology in tissue engineering research, this review highlights recent advances in the application of nano-engineered scaffolds designed to replace or restore the followed tissues: (i) skin; (ii) cartilage; (iii) bone; (iv) nerve; and (v) cardiac. PMID:28809213

Meeting the expectation of industry: an integrated approach for the teaching of mechanics and electronics to design students

NASA Astrophysics Data System (ADS)

Bingham, Guy A.; Southee, Darren J.; Page, Tom

2015-07-01

This paper examines the traditional engineering-based provision delivered to Product Design and Technology (B.Sc.) undergraduates at the Loughborough Design School and questions its relevancy against the increasing expectations of industry. The paper reviews final-year design projects to understand the level of transference of engineering-based knowledge into design practice and highlights areas of opportunity for improved teaching and learning. The paper discusses the development and implementation of an integrated approach to the teaching of Mechanics and Electronics to formalise and reinforce the key learning process of transference within the design context. The paper concludes with observations from the delivery of this integrated teaching and offers insights from student and academic perspectives for the further improvement of engineering-based teaching and learning.

Fiber Bragg gratings for civil engineering applications

NASA Astrophysics Data System (ADS)

Maher, Mohamed H.; Tabrizi, Khosrow; Prohaska, John D.; Snitzer, Elias

1996-04-01

Fiber Bragg gratings sensors offer a unique opportunity in civil engineering. They can be configured as a low noise distributed sensor network for measuring mechanical deformations and temperature. They are ideally suited for strain measurements of high modulus structural materials such as steel and concrete. There is considerable interest in the use of these sensors for infrastructural nondestructive testing and there have been several papers on the subject. We present some results of our experiments with fiber Bragg sensors as applied to structural engineering. These include the use of fiber gratings to measure strain behavior of steel, reinforced concrete, and some preliminary results on bituminous materials, such as asphalt concrete. In nondestructive testing using fiber Bragg gratings of structural materials the packaging of the sensors is important and is discussed.

Evaluation of seismic performance of reinforced concrete (RC) buildings under near-field earthquakes

NASA Astrophysics Data System (ADS)

Moniri, Hassan

2017-03-01

Near-field ground motions are significantly severely affected on seismic response of structure compared with far-field ground motions, and the reason is that the near-source forward directivity ground motions contain pulse-long periods. Therefore, the cumulative effects of far-fault records are minor. The damage and collapse of engineering structures observed in the last decades' earthquakes show the potential of damage in existing structures under near-field ground motions. One important subject studied by earthquake engineers as part of a performance-based approach is the determination of demand and collapse capacity under near-field earthquake. Different methods for evaluating seismic structural performance have been suggested along with and as part of the development of performance-based earthquake engineering. This study investigated the results of illustrious characteristics of near-fault ground motions on the seismic response of reinforced concrete (RC) structures, by the use of Incremental Nonlinear Dynamic Analysis (IDA) method. Due to the fact that various ground motions result in different intensity-versus-response plots, this analysis is done again under various ground motions in order to achieve significant statistical averages. The OpenSees software was used to conduct nonlinear structural evaluations. Numerical modelling showed that near-source outcomes cause most of the seismic energy from the rupture to arrive in a single coherent long-period pulse of motion and permanent ground displacements. Finally, a vulnerability of RC building can be evaluated against pulse-like near-fault ground motions effects.

Development of Advanced In-Cylinder Components and Tribological Systems for Low Heat Rejection Diesel Engines

NASA Technical Reports Server (NTRS)

Yonushonis, T. M.; Wiczynski, P. D.; Myers, M. R.; Anderson, D. D.; McDonald, A. C.; Weber, H. G.; Richardson, D. E.; Stafford, R. J.; Naylor, M. G.

1999-01-01

In-cylinder components and tribological system concepts were designed, fabricated and tested at conditions anticipated for a 55% thermal efficiency heavy duty diesel engine for the year 2000 and beyond. A Cummins L10 single cylinder research engine was used to evaluate a spherical joint piston and connecting rod with 19.3 MPa (2800 psi) peak cylinder pressure capability, a thermal fatigue resistant insulated cylinder head, radial combustion seal cylinder liners, a highly compliant steel top compression ring, a variable geometry turbocharger, and a microwave heated particulate trap. Components successfully demonstrated in the final test included spherical joint connecting rod with a fiber reinforced piston, high conformability steel top rings with wear resistant coatings, ceramic exhaust ports with strategic oil cooling and radial combustion seal cylinder liner with cooling jacket transfer fins. A Cummins 6B diesel was used to develop the analytical methods, materials, manufacturing technology and engine components for lighter weight diesel engines without sacrificing performance or durability. A 6B diesel engine was built and tested to calibrate analytical models for the aluminum cylinder head and aluminum block.

Characterization of terahertz waves on foreign materials of composite materials

NASA Astrophysics Data System (ADS)

Im, Kwang-Hee; Kim, Sun-Kyu; Chiou, Chien-Ping; Jung, Jong-An

2018-04-01

Carbon-fiber reinforced plastics (CFRP) are widely utilized due to their comparatively high performance in engineering structures. It is well understood that a nondestructive technique would be very beneficial. A new terahertz radiation has been recognized for its importance in technological applications. Recently, T-ray (terahertz ray) advances in technology and instrumentation have provided a probing field on the electromagnetic spectrum. In carbon composites, the penetration characterization of T-ray waves was fundamentally investigated in order to measure the painting thickness. Also, another study dealt with THz scan images of honeycomb sandwich composite panels using a refractive index (n), an absorption coefficient (α), the electrical conductivity of glass fiber embedded epoxy matrix composites, and carbon fiber reinforced plastics (CFRP) skin. For experiments, a method of detecting FRP composites with impact damage is presented, which utilizes aluminum wires intertwined with woven carbon fibers as they are inserted into the surface of the CFRP honeycomb sandwich panels. Intensive characterization of T-ray for the nondestructive evaluation (NDE) of carbon composite reinforced plastics (CFRP) composites is discussed in relation to the E-field influence with CFRP composite laminates.

Studies on mechanical properties of aluminium 6061 reinforced with titanium and E glass fibre metal matrix hybrid composites

NASA Astrophysics Data System (ADS)

Kumar, B. N. Ravi; Vidyasagar, H. N.; Shivanand, H. K.

2018-04-01

2Development of the mmc with fibers and filler materials as a replacement material for some engineering purpose such as automobiles, aerospace are indispensable. Therefore, the studies related to hybrid mmc's of Al6061 were noted in this paper. In this work, Al6061 reinforced with E glass fibers and micro Titanium particles. Hybrid composites was prepared by very feasible and commercially used technique Stir casting and by varying composition of Al6061, Titanium and E-glass fibre. Experiments were done by varying weight fraction of Titanium (0%, 1%, 3% and 5%) and E glass fibre (0%, 1%, 3% and 5%). Wire EDM were used to prepare the specimens required for tensile and hardness according to standards and tests conducted. The proportion of elements which are present the mmc's are identified by EDAX. Optical microscopy were conducted by SU3500 machine Scanning Electron Microscope and Microstructure shows the distribution of reinforced Ti particles and E glass fibres. The characterization of Al6061 hybrid mmc's is having significant impact on the mechanical properties.

Bisphenyl-Polymer/Carbon-Fiber-Reinforced Composite Compared to Titanium Alloy Bone Implant

PubMed Central

Petersen, Richard C.

2014-01-01

Aerospace/aeronautical thermoset bisphenyl-polymer/carbon-fiber-reinforced composites are considered as new advanced materials to replace metal bone implants. In addition to well-recognized nonpolar chemistry with related bisphenol-polymer estrogenic factors, carbon-fiber-reinforced composites can offer densities and electrical conductivity/resistivity properties close to bone with strengths much higher than metals on a per-weight basis. In vivo bone-marrow tests with Sprague-Dawley rats revealed far-reaching significant osseoconductivity increases from bisphenyl-polymer/carbon-fiber composites when compared to state-of-the-art titanium-6-4 alloy controls. Midtibial percent bone area measured from the implant surface increased when comparing the titanium alloy to the polymer composite from 10.5% to 41.6% at 0.8 mm, P < 10−4, and 19.3% to 77.7% at 0.1 mm, P < 10−8. Carbon-fiber fragments planned to occur in the test designs, instead of producing an inflammation, stimulated bone formation and increased bone integration to the implant. In addition, low-thermal polymer processing allows incorporation of minerals and pharmaceuticals for future major tissue-engineering potential. PMID:25553057

Bisphenyl-Polymer/Carbon-Fiber-Reinforced Composite Compared to Titanium Alloy Bone Implant.

PubMed

Petersen, Richard C

2011-05-03

Aerospace/aeronautical thermoset bisphenyl-polymer/carbon-fiber-reinforced composites are considered as new advanced materials to replace metal bone implants. In addition to well-recognized nonpolar chemistry with related bisphenol-polymer estrogenic factors, carbon-fiber-reinforced composites can offer densities and electrical conductivity/resistivity properties close to bone with strengths much higher than metals on a per-weight basis. In vivo bone-marrow tests with Sprague-Dawley rats revealed far-reaching significant osseoconductivity increases from bisphenyl-polymer/carbon-fiber composites when compared to state-of-the-art titanium-6-4 alloy controls. Midtibial percent bone area measured from the implant surface increased when comparing the titanium alloy to the polymer composite from 10.5% to 41.6% at 0.8 mm, P < 10 -4 , and 19.3% to 77.7% at 0.1 mm, P < 10 -8 . Carbon-fiber fragments planned to occur in the test designs, instead of producing an inflammation, stimulated bone formation and increased bone integration to the implant. In addition, low-thermal polymer processing allows incorporation of minerals and pharmaceuticals for future major tissue-engineering potential.

Evaluation of thermal expansion coefficient of carbon fiber reinforced composites using electronic speckle interferometry.

PubMed

Dong, Chengzhi; Li, Kai; Jiang, Yuxi; Arola, Dwayne; Zhang, Dongsheng

2018-01-08

An optical system for measuring the coefficient of thermal expansion (CTE) of materials has been developed based on electronic speckle interferometry. In this system, the temperature can be varied from -60°C to 180°C with a Peltier device. A specific specimen geometry and an optical arrangement based on the Michelson interferometer are proposed to measure the deformation along two orthogonal axes due to temperature changes. The advantages of the system include its high sensitivity and stability over the whole range of measurement. The experimental setup and approach for estimating the CTE was validated using an Aluminum alloy. Following this validation, the system was applied for characterizing the CTE of carbon fiber reinforced composite (CFRP) laminates. For the unidirectional fiber reinforced composites, the CTE varied with fiber orientation and exhibits anisotropic behavior. By stacking the plies with specific angles and order, the CTE of a specific CFRP was constrained to a low level with minimum variation temperature. The optical system developed in this study can be applied to CTE measurement for engineering and natural materials with high accuracy.

Calculation of reinforced-concrete frame strength under a simultaneous static cross section load and a column lateral impact

NASA Astrophysics Data System (ADS)

Belov, Nikolay; Yugov, Nikolay; Kopanitsa, Dmitry; Kopanitsa, Georgy; Yugov, Alexey; Kaparulin, Sergey; Plyaskin, Andrey; Kalichkina, Anna; Ustinov, Artyom

2016-01-01

When designing buildings with reinforced concrete that are planned to resist dynamic loads it is necessary to calculate this structural behavior under operational static and emergency impact and blast loads. Calculations of the structures under shock-wave loads can be performed by solving dynamic equations that do not consider static loads. Due to this fact the calculation of reinforced concrete frame under a simultaneous static and dynamic load in full 3d settings becomes a very non trivial and resource consuming problem. This problem can be split into two tasks. The first one is a shock-wave problem that can be solved using software package RANET-3, which allows solving the problem using finite elements method adapted for dynamic task. This method calculates strain-stress state of the material and its dynamic destruction, which is considered as growth and consolidation of micro defects under loading. On the second step the results of the first step are taken as input parameters for quasi static calculation of simultaneous static and dynamic load using finite elements method in AMP Civil Engineering-11.

Glass Fiber Reinforced Metal Pressure Vessel Design Guide

NASA Technical Reports Server (NTRS)

Landes, R. E.

1972-01-01

The Engineering Guide presents curves and general equations for safelife design of lightweight glass fiber reinforced (GFR) metal pressure vessels operating under anticipated Space Shuttle service conditions. The high composite vessel weight efficiency is shown to be relatively insensitive to shape, providing increased flexibility to designers establishing spacecraft configurations. Spheres, oblate speroids, and cylinders constructed of GFR Inconel X-750, 2219-T62 aluminum, and cryoformed 301 stainless steel are covered; design parameters and performance efficiencies for each configuration are compared at ambient and cryogenic temperature for an operating pressure range of 690 to 2760 N/sq cm (1000 to 4000 psi). Design variables are presented as a function of metal shell operating to sizing (proof) stress ratios for use with fracture mechanics data generated under a separate task of this program.

A seismic optimization procedure for reinforced concrete framed buildings based on eigenfrequency optimization

NASA Astrophysics Data System (ADS)

Arroyo, Orlando; Gutiérrez, Sergio

2017-07-01

Several seismic optimization methods have been proposed to improve the performance of reinforced concrete framed (RCF) buildings; however, they have not been widely adopted among practising engineers because they require complex nonlinear models and are computationally expensive. This article presents a procedure to improve the seismic performance of RCF buildings based on eigenfrequency optimization, which is effective, simple to implement and efficient. The method is used to optimize a 10-storey regular building, and its effectiveness is demonstrated by nonlinear time history analyses, which show important reductions in storey drifts and lateral displacements compared to a non-optimized building. A second example for an irregular six-storey building demonstrates that the method provides benefits to a wide range of RCF structures and supports the applicability of the proposed method.

A thermoplastic polyimidesulfone. [synthesis of processable and solvent resistant system

NASA Technical Reports Server (NTRS)

St. Clair, T. L.; Yamaki, D. A.

1984-01-01

A polymer system has been prepared which has the excellent thermoplastic properties generally associated with polysulfones, and the solvent resistance and thermal stability of aromatic polyimides. This material, with improved processability over the base polyimide, can be processed in the 260-325 C range in such a manner as to yield high quality, tough unfilled moldings; strong, high-temperature-resistant adhesive bonds; and well consolidated, graphite-fiber-reinforced moldings (composites). The unfilled moldings have physical properties that are similar to aromatic polysulfones which demonstrates the potential as an engineering thermoplastic. The adhesive bonds exhibit excellent retention of initial strength levels even after thermal aging for 5000 hours at 232 C. The graphite-fiber-reinforced moldings have mechanical properties which makes this polymer attractive for the fabrication of structural composites.

Present State of the Art of Composite Fabric Forming: Geometrical and Mechanical Approaches

PubMed Central

Cherouat, Abel; Borouchaki, Houman

2009-01-01

Continuous fibre reinforced composites are now firmly established engineering materials for the manufacture of components in the automotive and aerospace industries. In this respect, composite fabrics provide flexibility in the design manufacture. The ability to define the ply shapes and material orientation has allowed engineers to optimize the composite properties of the parts. The formulation of new numerical models for the simulation of the composite forming processes must allow for reduction in the delay in manufacturing and an optimization of costs in an integrated design approach. We propose two approaches to simulate the deformation of woven fabrics: geometrical and mechanical approaches.

Nondestructive testing of externally reinforced structures for seismic retrofitting using flax fiber reinforced polymer (FFRP) composites

NASA Astrophysics Data System (ADS)

Ibarra-Castanedo, C.; Sfarra, S.; Paoletti, D.; Bendada, A.; Maldague, X.

2013-05-01

Natural fibers constitute an interesting alternative to synthetic fibers, e.g. glass and carbon, for the production of composites due to their environmental and economic advantages. The strength of natural fiber composites is on average lower compared to their synthetic counterparts. Nevertheless, natural fibers such as flax, among other bast fibers (jute, kenaf, ramie and hemp), are serious candidates for seismic retrofitting applications given that their mechanical properties are more suitable for dynamic loads. Strengthening of structures is performed by impregnating flax fiber reinforced polymers (FFRP) fabrics with epoxy resin and applying them to the component of interest, increasing in this way the load and deformation capacities of the building, while preserving its stiffness and dynamic properties. The reinforced areas are however prompt to debonding if the fabrics are not mounted properly. Nondestructive testing is therefore required to verify that the fabric is uniformly installed and that there are no air gaps or foreign materials that could instigate debonding. In this work, the use of active infrared thermography was investigated for the assessment of (1) a laboratory specimen reinforced with FFRP and containing several artificial defects; and (2) an actual FFRP retrofitted masonry wall in the Faculty of Engineering of the University of L'Aquila (Italy) that was seriously affected by the 2009 earthquake. Thermographic data was processed by advanced signal processing techniques, and post-processed by computing the watershed lines to locate suspected areas. Results coming from the academic specimen were compared to digital speckle photography and holographic interferometry images.

Nitrous Oxide/Paraffin Hybrid Rocket Engines

NASA Technical Reports Server (NTRS)

Zubrin, Robert; Snyder, Gary

2010-01-01

Nitrous oxide/paraffin (N2OP) hybrid rocket engines have been invented as alternatives to other rocket engines especially those that burn granular, rubbery solid fuels consisting largely of hydroxyl- terminated polybutadiene (HTPB). Originally intended for use in launching spacecraft, these engines would also be suitable for terrestrial use in rocket-assisted takeoff of small airplanes. The main novel features of these engines are (1) the use of reinforced paraffin as the fuel and (2) the use of nitrous oxide as the oxidizer. Hybrid (solid-fuel/fluid-oxidizer) rocket engines offer advantages of safety and simplicity over fluid-bipropellant (fluid-fuel/fluid-oxidizer) rocket en - gines, but the thrusts of HTPB-based hybrid rocket engines are limited by the low regression rates of the fuel grains. Paraffin used as a solid fuel has a regression rate about 4 times that of HTPB, but pure paraffin fuel grains soften when heated; hence, paraffin fuel grains can, potentially, slump during firing. In a hybrid engine of the present type, the paraffin is molded into a 3-volume-percent graphite sponge or similar carbon matrix, which supports the paraffin against slumping during firing. In addition, because the carbon matrix material burns along with the paraffin, engine performance is not appreciably degraded by use of the matrix.

Advanced Gas Turbine (AGT) Technology Project

NASA Technical Reports Server (NTRS)

1986-01-01

Engine testing, ceramic component fabrication and evaluation, component performance rig testing, and analytical studies comprised AGT 100 activities during the 1985 year. Ten experimental assemblies (builds) were evaluated using two engines. Accrued operating time was 120 hr of burning and 170 hr total, bringing cumulative total operating time to 395 hr, all devoid of major failures. Tests identified the generator seals as the primary working fluid leakage sources. Power transfer clutch operation was demonstrated. An alpha SiC gasifier rotor engine test resulted in blade tip failures. Recurring case vibration and shaft whip have limited gasifier shaft speeds to 84%. Ceramic components successfully engine tested now include the SiC scroll assembly, Si3N3 turbine rotor, combustor assembly, regenerator disk bulkhead, turbine vanes, piston rings, and couplings. A compressor shroud design change to reduce heat recirculation back to the inlet was executed. Ceramic components activity continues to focus on the development of state-of-the-art material strength characteristics in full-scale engine hardware. Fiber reinforced glass-ceramic composite turbine (inner) backplates were fabricated by Corning Glass Works. The BMAS/III material performed well in engine testing. Backplates of MAS material have not been engine tested.

46 CFR 160.035-5 - Construction of steel motor-propelled lifeboats with and without radio cabin.

Code of Federal Regulations, 2010 CFR

2010-10-01

... reinforced plastic, it shall be made of fire retardant material. The top of the engine box shall be fitted... tanks shall have a thickness of not less than 0.187 inch. The resins used shall be of a fire retardant... cloth shall be used. Tank laminates shall not be constructed exclusively with fibrous glass fabrics. An...

PBF Cooling Tower under construction. Cold water basin is five ...

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

PBF Cooling Tower under construction. Cold water basin is five feet deep. Foundation and basin walls are reinforced concrete. Camera facing west. Pipe openings through wall in front are outlets for return flow of cool water to reactor building. Photographer: John Capek. Date: September 4, 1968. INEEL negative no. 68-3473 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

High temperature composites. Status and future directions

NASA Technical Reports Server (NTRS)

Signorelli, R. A.

1982-01-01

A summary of research investigations of manufacturing methods, fabrication methods, and testing of high temperature composites for use in gas turbine engines is presented. Ceramic/ceramic, ceramic/metal, and metal/metal composites are considered. Directional solidification of superalloys and eutectic alloys, fiber reinforced metal and ceramic composites, ceramic fibers and whiskers, refractory coatings, metal fiber/metal composites, matrix metal selection, and the preparation of test specimens are discussed.

A Novel Method for Producing Light GMT Sheets by a Pneumatic Technique

NASA Astrophysics Data System (ADS)

Dai, H.-L.; Rao, Y.-N.

2015-09-01

A novel method for producing a kind of light glass-mat- reinforced thermoplastic (GMT) sheets by using a pneumatic technique is presented. The tensile and flexural properties of produced light GMT sheets, with various lengths of glass fibers and PP content, were determined experimentally. Results of the experimental investigation show that the light GMT sheets are fully suitable for engineering applications.

PMR polyimide composites for aerospace applications

NASA Technical Reports Server (NTRS)

Serafini, T. T.

1982-01-01

Fiber reinforced PMR polyimides are finding increased acceptance as engineering materials for high performance structural applications. Prepreg materials based on this novel class of highly processable, high temperature resistant polyimides, are commercially available and the PMR concept was incorporated in several industrial applications. The status of PMR polyimides is reviewed. Emphasis is given to the chemistry, processing, and applications of the first generation PMR polyimides known as PMR-15.

Composite materials for the extravehicular mobility unit

NASA Technical Reports Server (NTRS)

Barrera, Enrique V.; Tello, Hector M.

1992-01-01

The extravehicular mobility unit (EMU), commonly known as the astronaut space suit assembly (SSA) and primary life support system (PLSS), has evolved through the years to incorporate new and innovative materials in order to meet the demands of the space environment. The space shuttle program which is seeing an increasing level of extravehicular activity (EVA), also called space walks, along with interest in an EMU for Lunar-Mars missions means even more demanding conditions are being placed on the suit and PLSS. The project for this NASA-ASEE Summer Program was to investigate new materials for these applications. The focus was to emphasize the use of composite materials for every component of the EMU to enhance the properties while reducing the total weight of the EMU. To accomplish this, development of new materials called fullerene reinforced materials (FRM's) was initiated. Fullerenes are carbon molecules which when added to a material significantly reduce the weight of that material. The Faculty Fellow worked directly on the development of the fullerene reinforced materials. A chamber for fullerene production was designed and assembled and first generation samples were processed. He also supervised with the JSC Colleague, a study of composite materials for the EMU conducted by the student participant in the NASA-ASEE Program, Hector Tello a Rice University graduate student, and by a NASA Aerospace Technologist (Materials Engineer) Evelyne Orndoff, in the Systems Engineering Analysis Office (EC7), also a Rice University graduate student. Hector Tello conducted a study on beryllium and Be alloys and initiated a study of carbon and glass reinforced composites for space applications. Evelyne Orndoff compiled an inventory of the materials on the SSA. Ms. Orndoff also reviewed SSA material requirements and cited aspects of the SSA design where composite materials might be further considered. Hector Tello spent part of his time investigating the solar radiation sensitivity of anodic coatings. This project was directed toward the effects of ultra-violet radiation on high emissivity anodic coatings. The work of both Evelyne Orndoff and Hector Tello is of interest to the Engineering Directorate at NASA/JSC and is also directed toward their research as Rice University graduate students.

Study on the fabricating process monitoring of thermoplastic based materials packaged OFBG and their sensing properties

NASA Astrophysics Data System (ADS)

Wang, Chuan; Zhou, Zhi; Zhang, Zhichun; Ou, Jinping

2007-04-01

As common materials or engineering materials, thermoplastic resin based materials can be used not only directly fabricating products but also FRTP(fiber reinforced thermoplastic polymer) materials for other uses. As one kind of FRTP material, GFRPP(glass fiber reinforced polypropylene) has lots of merits, such as: light weight, high strength, high tenacity, high elongation percentage, good durability, reshaping character and no environmental pollution characters. And they also can be conveniently formed hoop rebar in civil engineering. While a new kind of GFRPP-OFBG smart rod which combined GFRPP and OFBG together can be used as not only structure materials but also sensing materials. Meanwhile, PP packaged OFBG strain sensor can be expected for its low modulus, good sensitivity and good durability. Furthermore, it can be used for large strain measuring. In this paper, we have successfully fabricated a new kind of GFRPP-OFBG(Glass Fiber Reinforced Polypropylene-Optic Fiber Bragg Grating) rod by our own thermoplastic pultrusion production line and a new kind of PP packaged OFBG strain sensor by extruding techniques. And we monitored the inner strain and temperature changes with tow OFBG simultaneously of the fabricating process. The results show that: OFBG can truly reflect the strain and temperature changes in both the GFRPP rod and the PP packaged OFBG, these are very useful to modify our processing parameters. And we also find that because of the shrinkage of PP, this new kind of PP packaged OFBG have -13000μɛ storage, and the strain sensing performance is still very well, so which can be used for large strain measuring. Besides these, GFRPP-OFBG smart rod has good sensing performance in strain sensing just like that of FRSP-OFBG rod, the strain sensitivity coefficient is about1.19pm/μɛ. Besides these, the surface of GFRPP-OFBG rods can be handled just as steel bars and also can be bended and reshaped. These are all very useful and very important for the use of FRP materials in civil engineering structures.

Engineering Knowledge and Student Development: An Institutional and Pedagogical Critique of Engineering Education

NASA Astrophysics Data System (ADS)

Tang, Xiaofeng

Educators have recommended the integration of engineering and the liberal arts as a promising educational model to prepare young engineers for global economic, environmental, sociotechnical, and ethical challenges. Drawing upon philosophy of technology, engineering studies, and educational psychology, this dissertation examines diverse visions and strategies for integrating engineering and liberal education and explores their impacts on students' intellectual and moral development. Based on archival research, interviews, and participant observation, the dissertation presents in-depth case studies of three educational initiatives that seek to blend engineering with the humanities, social sciences, and arts: Harvey Mudd College, the Picker Engineering Program at Smith College, and the Programs in Design and Innovation at Rensselaer Polytechnic Institute. The research finds that learning engineering in a liberal arts context increases students' sense of "owning" their education and contributes to their communication, teamwork, and other non-technical professional skills. In addition, opportunities for extensive liberal arts learning in the three cases encourage some students to pursue alternative, less technocentric approaches to engineering. Nevertheless, the case studies suggest that the epistemological differences between the engineering and liberal arts instructors help maintain a technical/social dualism among most students. Furthermore, the dissertation argues a "hidden curriculum," which reinforces the dominant ideology in the engineering profession, persists in the integrated programs and prevents the students from reflecting on the broad social context of engineering and critically examining the assumptions upheld in the engineering profession.

Measurement of ageing effect on chloride diffusion coefficients in cementitious matrices

NASA Astrophysics Data System (ADS)

Andrade, C.; Castellote, M.; d'Andrea, R.

2011-05-01

Most of the low-level nuclear waste disposal facilities are based in engineered multi barrier systems where reinforced concrete is one of the basic materials. The calculation of the time until steel reinforcement depassivation is a need due to the demand of prediction of the service life of concrete structures in radioactive repositories. In doing that, one of the main steps is the transport of chloride ions towards the reinforcement, as one of the most aggressive agents for the rebars in concrete is chloride ions. Ageing of concrete related to chloride penetration leads to significant decrease of the "apparent diffusion" coefficient with time. If this effect is not considered, considerable bias can be introduced when predicting service life of reinforced concrete of repositories. Several effects have been addressed on their influence on the ageing of concrete, including the evolution with time of the concrete pore refinement, the binding of chlorides to the cement phases and to the changes of chloride "surface concentration". These effects have been studied in specimens made with different mixes trying to represent a wide range of mineral addition proportions. The analysis of their evolution with time has shown that the resistivity alone or the joint consideration of resistivity and binding capacity ( Cb/ Cf), are appropriate parameters to appraise the diffusivity ageing. For practical reasons, an accelerated procedure is proposed in order to calculate ageing for short periods of time.

Dynamic shear-lag model for understanding the role of matrix in energy dissipation in fiber-reinforced composites.

PubMed

Liu, Junjie; Zhu, Wenqing; Yu, Zhongliang; Wei, Xiaoding

2018-07-01

Lightweight and high impact performance composite design is a big challenge for scientists and engineers. Inspired from well-known biological materials, e.g., the bones, spider silk, and claws of mantis shrimp, artificial composites have been synthesized for engineering applications. Presently, the design of ballistic resistant composites mainly emphasizes the utilization of light and high-strength fibers, whereas the contribution from matrix materials receives less attention. However, recent ballistic experiments on fiber-reinforced composites challenge our common sense. The use of matrix with "low-grade" properties enhances effectively the impact performance. In this study, we establish a dynamic shear-lag model to explore the energy dissipation through viscous matrix materials in fiber-reinforced composites and the associations of energy dissipation characteristics with the properties and geometries of constituents. The model suggests that an enhancement in energy dissipation before the material integrity is lost can be achieved by tuning the shear modulus and viscosity of a matrix. Furthermore, our model implies that an appropriately designed staggered microstructure, adopted by many natural composites, can repeatedly activate the energy dissipation process and thus improve dramatically the impact performance. This model demonstrates the role of matrix in energy dissipation, and stimulates new advanced material design concepts for ballistic applications. Biological composites found in nature often possess exceptional mechanical properties that man-made materials haven't be able to achieve. For example, it is predicted that a pencil thick spider silk thread can stop a flying Boeing airplane. Here, by proposing a dynamic shear-lag model, we investigate the relationships between the impact performance of a composite with the dimensions and properties of its constituents. Our analysis suggests that the impact performance of fiber-reinforced composites could improve surprisingly with "low-grade" matrix materials, and discontinuities (often regarded as "defects") may play an important role in energy dissipation. Counter-intuitive as it may seem, our work helps understanding the secrets of the outstanding dynamic properties of some biological materials, and inspire novel ideas for man-made composites. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Development and Characterization of SiC)/ MoSi2-Si3N4(p) Hybrid Composites

NASA Technical Reports Server (NTRS)

Hebsur, Mohan G.

1998-01-01

Intermetallic compound MoSi2 has long been known as a high temperature material that has excellent oxidation resistance and electrical/thermal conductivity. Also its low cost, high melting point (2023 C), relatively low density (6.2 g/cu cm versus 9 g/cu cm for current engine materials), and ease of machining, make it an attractive structural material. However, the use of MoSi2 has been hindered due to its poor toughness at low temperatures, poor creep resistance at high temperatures, and accelerated oxidation (also known as 'pest' oxidation) at temperatures between approximately 450 and 550 C. Continuous fiber reinforcing is very effective means of improving both toughness and strength. Unfortunately, MoSi2 has a relatively high coefficient of thermal expansion (CTE) compared to potential reinforcing fibers such as SiC. The large CTE mismatch between the fiber and the matrix resulted in severe matrix cracking during thermal cycling. Addition of about 30 to 50 vol % of Si3N4 particulate to MoSi2 improved resistance to low temperature accelerated oxidation by forming a Si2ON2 protective scale and thereby eliminating catastrophic 'pest failure'. The Si3N4 addition also improved the high temperature creep strength by nearly five orders of magnitude, doubled the room temperature toughness and significantly lowered the CTE of the MoSi2 and eliminated matrix cracking in SCS-6 reinforced composites even after thermal cycling. The SCS-6 fiber reinforcement improved the room temperature fracture toughness by seven times and impact resistance by five times. The composite exhibited excellent strength and toughness improvement up to 1400 C. More recently, tape casting was adopted as the preferred processing of MoSi2-base composites for improved fiber spacing, ability to use small diameter fibers, and for lower cost. Good strength and toughness values were also obtained with fine diameter Hi-Nicalon tow fibers. This hybrid composite remains competitive with ceramic matrix composites as a replacement for Ni-base superalloys in aircraft engine applications.

Designing computer learning environments for engineering and computer science: The scaffolded knowledge integration framework

NASA Astrophysics Data System (ADS)

Linn, Marcia C.

1995-06-01

Designing effective curricula for complex topics and incorporating technological tools is an evolving process. One important way to foster effective design is to synthesize successful practices. This paper describes a framework called scaffolded knowledge integration and illustrates how it guided the design of two successful course enhancements in the field of computer science and engineering. One course enhancement, the LISP Knowledge Integration Environment, improved learning and resulted in more gender-equitable outcomes. The second course enhancement, the spatial reasoning environment, addressed spatial reasoning in an introductory engineering course. This enhancement minimized the importance of prior knowledge of spatial reasoning and helped students develop a more comprehensive repertoire of spatial reasoning strategies. Taken together, the instructional research programs reinforce the value of the scaffolded knowledge integration framework and suggest directions for future curriculum reformers.

Current Status and Recent Research Achievements in SiC/SiC Composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katoh, Yutai; Snead, Lance L.; Henager, Charles H.

2014-12-01

The development and maturation of the silicon carbide fiber-reinforced silicon carbide matrix (SiC/SiC) composite system for fusion applications has seen the evolution from fundamental development and understanding of the material system and its behavior in a hostile irradiation environment to the current effort which essentially is a broad-based program of technology, directed at moving this material class from a laboratory curiosity to an engineering material. This paper lays out the recent international scientific and technological achievements in the development of SiC/SiC composite material technologies for fusion application and will discuss future research directions. It also reviews the materials system inmore » the larger context of progress to maturity as an engineering material for both the larger nuclear community and for general engineering applications.« less

An experimental study on stabilization of Pekan clay using polyethylene and polypropylene

NASA Astrophysics Data System (ADS)

Zukri, Azhani; Nazir, Ramli; Mender, Fatin Nabilah

2017-10-01

Many countries are expressing concern over the growing issues of polyethylene terephthalate (PET) bottles and polypropylene (PP) products made by the household sector. The rapid increase in the generation of plastic waste all around the world is due to the economic development and population growth. PP is the world's second-most widely produced synthetic plastic, after polyethylene. Statistics show that nearly 50% of the municipal solid waste in Malaysia comes from the institutional, industrial, residential, and construction waste. This paper presents the results of an investigation on the utilisation of fibres as products of PET bottles and PP products in order to improve the engineering properties of clay soil in Pekan. The soil samples were taken from Kampung Tanjung Medang, Pekan, Pahang. The basic properties of the clay soil were determined as follows; optimum moisture content: 32.5%, maximum dry density: 13.43 kN/m3, specific gravity: 2.51, liquid limit: 74.67%, plastic limit: 45.98%, and plasticity index: 28.69%. This investigation concentrates on the shear strength of the reinforced clay soils with PET and PP in random orientation. The reinforced soil samples were subjected to unconfined compression test (UCT) to differentiate their shear strength with that of the unreinforced soil. The tests found that the waste fibres (PET and PP) improved the strength properties of the Pekan clayey soils. The unconfined compressive strength (UCS) value increased with the increasing percentage of PET fibre and reached the optimum content at 10% reinforcement, where it showed the highest improvement of 365 kN/m2 from 325 kN/m2 and depleted when the optimum content reached 20% reinforcement. For PP fibre, the reinforced soil showed the highest UCS at 20% reinforcement with the improvement of 367 kN/m2. The study concluded that the PET and PP fibres can be utilised successfully as reinforcement materials for the stabilisation of clayey soils. The use of these waste compounds as alternative materials for clay soil stabilisation is reasonable and cost effective since they are constantly available.

Finite Element Model Characterization Of Nano-Composite Thermal And Environmental Barrier Coatings

NASA Technical Reports Server (NTRS)

Yamada, Yoshiki; Zhu, Dongming

2011-01-01

Thermal and environmental barrier coatings have been applied for protecting Si based ceramic matrix composite components from high temperature environment in advanced gas turbine engines. It has been found that the delamination and lifetime of T/EBC systems generally depend on the initiation and propagation of surface cracks induced by the axial mechanical load in addition to severe thermal loads. In order to prevent T/EBC systems from surface cracking and subsequent delamination due to mechanical and thermal stresses, T/EBC systems reinforced with nano-composite architectures have showed promise to improve mechanical properties and provide a potential crack shielding mechanism such as crack bridging. In this study, a finite element model (FEM) was established to understand the potential beneficial effects of nano-composites systems such as SiC nanotube-reinforced oxide T/EBC systems.

Air Force Civil Engineer, Volume 16, Number 1, 2008

DTIC Science & Technology

2008-01-01

concrete pavements at any U.S. Air...34 OUT-TO-OUT OF CONCRETE 1’-3" TYP #6 REBAR , TYP, OVERLAP 4’ #6 REBAR , SPACED 15" 3" M IN CO VE R DRILL AND EPOXY COAT WITH OIL PRIOR TO CONCRETE ... concrete portion of the job. The entire project was designed with concrete of varying depths, reinforced with #5 rebar on 1-foot centers.

Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Inspection of the Engineering Condition of Underwater Concrete Structures.

DTIC Science & Technology

1989-04-01

corrosion of rebar Spalling of concrete surface IIl Detect hidden and beginning Location of rebar damage Beginning corrosion of rebar ...honeycombs MD Moderate defects: spalling of concrete minor corrosion of exposed rebar rust stains along rebar with or without visible cracking softening of...velocity. . Replenishment of the attacking chemical hgents. h. Higher temperatures. i. Corrosion of reinforcing steel. 46. Note that concrete which

Breaking Free from Myths about Teaching and Learning: Innovation as an Engine for Student Success

ERIC Educational Resources Information Center

Zmuda, Allison

2010-01-01

When you hear students say that what they learn in school doesn't have much to do with life, or that getting the answer right is the most important thing, or that learning is only about getting good grades, what they're doing is reflecting a general set of expectations that are reinforced by schools themselves. Here's a book that boldly contends…

CONSTRUCTION PROGRESS PHOTO OF HOT PILOT PLANT (CP640) LOOKING NORTHWEST ...

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

CONSTRUCTION PROGRESS PHOTO OF HOT PILOT PLANT (CP-640) LOOKING NORTHWEST SHOWING FORMING AND PLACEMENT OF REINFORCING STEEL FOR SOUTH WALLS OF CELLS 1, 3, 4 AND 5 AND WEST WALL FOR CELLS 1 AND 2; CONSTRUCTION 13 PERCENT COMPLETE. INL PHOTO NUMBER NRTS 59-6436. J. Anderson, Photographer, 12/18/1959 - Idaho National Engineering Laboratory, Idaho Chemical Processing Plant, Fuel Reprocessing Complex, Scoville, Butte County, ID

Mobility Research at TARDEC (Briefing Charts)

DTIC Science & Technology

2015-03-10

UWM UIC UWM UWM Gap Collaboration 4 ARC & RIF Fund: $255k+$250K New ANCF shell element Fiber -reinforced composite rubber Validation and benchmark 2013...U.S. ARMY TANK AUTOMOTIVE RESEARCH, DEVELOPMENT AND ENGINEERING CENTER Mobility Research at TARDEC Dr. P. Jayakumar, S. Arepally Analytics 1...t s 5 9 - - - -3 t s 7 98 - - - . . . .t s Drucker-Prager Elasto- Plastic Soil Elastic Soil 6 A Physics-Based High Performance

Coupling of Peridynamics and Finite Element Formulation for Multiscale Simulations

DTIC Science & Technology

2012-10-16

unidirectional fiber - reinforced composites, Computer Methods in Applied Mechanics and Engineering 217 (2012) 247-261. [44] S. A. Silling, M. Epton...numerical testing for different grid widths to horizon ratios , (4) development of an approach to add another material variable in the given approach...partition of unity principle, (3) numerical testing for different grid widths to horizon ratios , (4) development of an approach to add another

PMR polyimides-review and update

NASA Technical Reports Server (NTRS)

Serafini, T. T.; Delvigs, P.; Alston, W. B.

1982-01-01

Fiber reinforced PMR polyimides are finding increased acceptance as engineering materials for high performance structural applications. Prepreg materials based on this novel class of highly processable, high temperature resistant polyimides are commercially available and the PMR concept is used by other investigators. The current status of first and second generation PMR polyimides were reviewed. Emphasis is given to the chemistry, processing and applications of the first generation material known as PMR-15.

Engineering Devices to Treat Epilepsy: A Clinical Perspective

DTIC Science & Technology

2001-10-25

Research over the next three decades reinforced the idea that seizures likely spread through discrete, functional neuronal networks [2]. Over the last...15 years, researchers have demonstrated that it is possible to modulate the activity of functional neuronal networks in animal models of epilepsy by...hypothalamus [5], mamillary bodies [6], cerebellum [7], basal ganglia [8], locus ceruleus [9] and the substantia nigra [10]. At the same time some

Bio-engineering traits of Pinus radiata D.Don

NASA Astrophysics Data System (ADS)

Giadrossich, Filippo; Marden, Michael; Marrosu, Roberto; Schwarz, Massimiliano; Phillips, Chris John; Cohen, Denis; Niedda, Marcello

2017-04-01

Pinus radiata is widely cultivated in New Zealand. Due to steep slopes and intense rainfall, the silviculture of Pinus radiata forests is important to control erosion and slope stability. Bio-engineering traits such as root distribution and root tensile strength are fundamental to understand the effectiveness of Pinus radiata. This information is needed to use the state of the art root reinforcement model (the Root Bundle Model) and the physically-based slope stability model SOSlope. Yet, little is known about root distribution and tensile strength for this specie. We measured soil moisture and carried out 30 field tensile tests on roots of Pinus radiata. We also measured root distribution data from 5 plants, digging arc of circles 0.6 radian around the trees in four opposite directions. We fully excavated the root system of two trees. Using the Root Bundle Model, results of our measurements allow estimation of root reinforcement. With the slope stability model SOSlope, information on the intensity and frequency of harvesting and on the development of weak zones that can be supported by a stand of Pinus radiata in relation to slope stability can be calculated. An added value is that the collected data allow us to make inferences between number and sizes of roots, and growth direction.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Michael E. Lopez-Alegria looks at the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. He and engineers from around the Agency are on a fact-finding tour for improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

NASA Image and Video Library

2003-12-08

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Michael E. Lopez-Alegria looks at the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. He and engineers from around the Agency are on a fact-finding tour for improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

KENNEDY SPACE CENTER, FLA. - - In the Orbiter Processing Facility astronaut Danny Olivas listens to Greg Grantham (left) talking about the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. Behind Olivas are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

NASA Image and Video Library

2003-12-08

KENNEDY SPACE CENTER, FLA. - - In the Orbiter Processing Facility astronaut Danny Olivas listens to Greg Grantham (left) talking about the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. Behind Olivas are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Scott E. Parazynski points to the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. With Parazynski are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

NASA Image and Video Library

2003-12-08

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Scott E. Parazynski points to the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. With Parazynski are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Scott E. Parazynski discusses the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. With him are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

NASA Image and Video Library

2003-12-08

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Scott E. Parazynski discusses the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. With him are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

Improving the performance of solventogenic clostridia by reinforcing the biotin synthetic pathway.

PubMed

Yang, Yunpeng; Lang, Nannan; Yang, Gaohua; Yang, Sheng; Jiang, Weihong; Gu, Yang

2016-05-01

An efficient production process is important for industrial microorganisms. The cellular efficiency of solventogenic clostridia, a group of anaerobes capable of producing a wealth of bulk chemicals and biofuels, must be improved for competitive commercialization. Here, using Clostridium acetobutylicum, a species of solventogenic clostridia, we revealed that the insufficient biosynthesis of biotin, a pivotal coenzyme for many important biological processes, is a major limiting bottleneck in this anaerobe's performance. To address this problem, we strengthened the biotin synthesis of C. acetobutylicum by overexpressing four relevant genes involved in biotin transport and biosynthesis. This strategy led to faster growth and improved the titer and productivity of acetone, butanol and ethanol (ABE solvents) of C. acetobutylicum in both biotin-containing and biotin-free media. Expressionally modulating these four genes by modifying the ribosome binding site further promoted cellular performance, achieving ABE solvent titer and productivity as high as 21.9g/L and 0.30g/L/h, respectively, in biotin-free medium; these values exceeded those of the wild-type strain by over 30%. More importantly, biotin synthesis reinforcement also conferred improved ability of C. acetobutylicum to use hexose and pentose sugars, further demonstrating the potential of this metabolic-engineering strategy in solventogenic clostridia. Copyright © 2016 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Investigation of mechanical properties of hemp/glass fiber reinforced nano clay hybrid composites

NASA Astrophysics Data System (ADS)

Unki, Hanamantappa Ningappa; Shivanand, H. K.; Vidyasagar, H. N.

2018-04-01

Over the last twenty to thirty years composite materials have been used in engineering field. Composite materials possess high strength, high strength to weight ratio due to these facts composite materials are becoming popular among researchers and scientists. The major proportion of engineering materials consists of composite materials. Composite materials are used in vast applications ranging from day-to-day household articles to highly sophisticated applications. In this paper an attempt is made to prepare three different composite materials using e-glass and Hemp. In this present investigation hybrid composite of Hemp, Glass fiber and Nano clay will be prepared by Hand-layup technique. The glass fiber used in this present investigation is E-glass fiber bi-directional: 90˚ orientation. The composite samples will be made in the form of a Laminates. The wt% of nanoclay added in the preparation of sample is 20 gm constant. The fabricated composite Laminate will be cut into corresponding profiles as per ASTM standards for Mechanical Testing. The effect of addition of Nano clay and variation of Hemp/glass fibers will be studied. In the present work, a new Hybrid composite is developed in which Hemp, E glass fibers is reinforced with epoxy resin and with Nano clay.

Shaping the micromechanical behavior of multi-phase composites for bone tissue engineering.

PubMed

Ranganathan, Shivakumar I; Yoon, Diana M; Henslee, Allan M; Nair, Manitha B; Smid, Christine; Kasper, F Kurtis; Tasciotti, Ennio; Mikos, Antonios G; Decuzzi, Paolo; Ferrari, Mauro

2010-09-01

Mechanical stiffness is a fundamental parameter in the rational design of composites for bone tissue engineering in that it affects both the mechanical stability and the osteo-regeneration process at the fracture site. A mathematical model is presented for predicting the effective Young's modulus (E) and shear modulus (G) of a multi-phase biocomposite as a function of the geometry, material properties and volume concentration of each individual phase. It is demonstrated that the shape of the reinforcing particles may dramatically affect the mechanical stiffness: E and G can be maximized by employing particles with large geometrical anisotropy, such as thin platelet-like or long fibrillar-like particles. For a porous poly(propylene fumarate) (60% porosity) scaffold reinforced with silicon particles (10% volume concentration) the Young's (shear) modulus could be increased by more than 10 times by just using thin platelet-like as opposed to classical spherical particles, achieving an effective modulus E approximately 8 GPa (G approximately 3.5 GPa). The mathematical model proposed provides results in good agreement with several experimental test cases and could help in identifying the proper formulation of bone scaffolds, reducing the development time and guiding the experimental testing. 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

TeachEnG: a Teaching Engine for Genomics.

PubMed

Kim, Minji; Kim, Yeonsung; Qian, Lei; Song, Jun S

2017-10-15

Bioinformatics is a rapidly growing field that has emerged from the synergy of computer science, statistics and biology. Given the interdisciplinary nature of bioinformatics, many students from diverse fields struggle with grasping bioinformatic concepts only from classroom lectures. Interactive tools for helping students reinforce their learning would be thus desirable. Here, we present an interactive online educational tool called TeachEnG (acronym for Teaching Engine for Genomics) for reinforcing key concepts in sequence alignment and phylogenetic tree reconstruction. Our instructional games allow students to align sequences by hand, fill out the dynamic programming matrix in the Needleman-Wunsch global sequence alignment algorithm, and reconstruct phylogenetic trees via the maximum parsimony, Unweighted Pair Group Method with Arithmetic mean (UPGMA) and Neighbor-Joining algorithms. With an easily accessible interface and instant visual feedback, TeachEnG will help promote active learning in bioinformatics. TeachEnG is freely available at http://teacheng.illinois.edu. The source code is available from https://github.com/KnowEnG/TeachEnG under the Artistic License 2.0. It is written in JavaScript and compatible with Firefox, Safari, Chrome and Microsoft Edge. songj@illinois.edu. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

* Three-Dimensional Bioprinting of Polycaprolactone Reinforced Gene Activated Bioinks for Bone Tissue Engineering.

PubMed

Cunniffe, Gráinne M; Gonzalez-Fernandez, Tomas; Daly, Andrew; Sathy, Binulal N; Jeon, Oju; Alsberg, Eben; Kelly, Daniel J

2017-09-01

Regeneration of complex bone defects remains a significant clinical challenge. Multi-tool biofabrication has permitted the combination of various biomaterials to create multifaceted composites with tailorable mechanical properties and spatially controlled biological function. In this study we sought to use bioprinting to engineer nonviral gene activated constructs reinforced by polymeric micro-filaments. A gene activated bioink was developed using RGD-γ-irradiated alginate and nano-hydroxyapatite (nHA) complexed to plasmid DNA (pDNA). This ink was combined with bone marrow-derived mesenchymal stem cells (MSCs) and then co-printed with a polycaprolactone supporting mesh to provide mechanical stability to the construct. Reporter genes were first used to demonstrate successful cell transfection using this system, with sustained expression of the transgene detected over 14 days postbioprinting. Delivery of a combination of therapeutic genes encoding for bone morphogenic protein and transforming growth factor promoted robust osteogenesis of encapsulated MSCs in vitro, with enhanced levels of matrix deposition and mineralization observed following the incorporation of therapeutic pDNA. Gene activated MSC-laden constructs were then implanted subcutaneously, directly postfabrication, and were found to support superior levels of vascularization and mineralization compared to cell-free controls. These results validate the use of a gene activated bioink to impart biological functionality to three-dimensional bioprinted constructs.

Design and implementation of a random neural network routing engine.

PubMed

Kocak, T; Seeber, J; Terzioglu, H

2003-01-01

Random neural network (RNN) is an analytically tractable spiked neural network model that has been implemented in software for a wide range of applications for over a decade. This paper presents the hardware implementation of the RNN model. Recently, cognitive packet networks (CPN) is proposed as an alternative packet network architecture where there is no routing table, instead the RNN based reinforcement learning is used to route packets. Particularly, we describe implementation details for the RNN based routing engine of a CPN network processor chip: the smart packet processor (SPP). The SPP is a dual port device that stores, modifies, and interprets the defining characteristics of multiple RNN models. In addition to hardware design improvements over the software implementation such as the dual access memory, output calculation step, and reduced output calculation module, this paper introduces a major modification to the reinforcement learning algorithm used in the original CPN specification such that the number of weight terms are reduced from 2n/sup 2/ to 2n. This not only yields significant memory savings, but it also simplifies the calculations for the steady state probabilities (neuron outputs in RNN). Simulations have been conducted to confirm the proper functionality for the isolated SPP design as well as for the multiple SPP's in a networked environment.

Comparison of Failure Process of Bended Beams Reinforced with Steel Bars and GFRP Bars

NASA Astrophysics Data System (ADS)

Kaszyńska, Maria; Błyszko, Jarosław; Olczyk, Norbert

2017-10-01

The Fibre Reinforced Polymer (FRP) composite rebar has been used in civil engineering structures for several years. It has many characteristics, which not only are equal to those of steel rebar, but significantly surpass them. The composite rebar has high corrosion resistance, electromagnetic neutrality and has much higher tensile strength than steel. Also, because of its low weight and easy processing composite rebar is convenient for shipment and use. Development of architectural concrete technology in past years opens new, interesting perspectives for use of composite rebar. However, implementation of those concretes in structures is often burdened with many issues, especially concerning faulty performance. One of it is rebar’s corrosion, visible on the surface of the element as rusty stains. Even if the structure was properly developed meeting all the requirements for texture, porosity or colour uniformity, and rusty stains can completely destroy the final decorative effect of concrete’s surface. Despite many advantages, the use of composite rebar in reinforced structures creates significant number of new “behaviours” in its different working stages. Structures reinforced with the steel rebar will behave differently than the ones with composite FRP rebar under continuous load, in case of a fire, exposed to aggressive environment or at breaking point. In the latter, significant role plays its linear-elastic behaviour in the whole tensile range till rupture. This means that the FPR rebar does not exhibit plastic deformation and reaches its bearing capacity suddenly without any visible signs. This should be considered during designing stage and included as an additional reduction coefficient. The article presents result of research and analysis of destructive tests performed on concrete beams reinforced with traditional steel rebar and composite rebar made of glass fibre and braided with basaltic (GFRP). Four single-span simply supported beams under static load were tested. Both types of beams were designed to have the same bearing capacity. Beams reinforced with GFRP rebar exhibited much bigger cracking than traditionally reinforced bars. The width of cracks appearing in beams reinforced with GFRP bars was equal or greater than limit values (0.4 mm) even though the ratio of moment of resistance and cracking moment was greater than 3. The composite rebar exhibits many significant advantages over steel rebar, but its rather low Young’s modulus comparing to steel causes exceeded deflection and cracking of bended concrete elements.

Application of Glass Fiber Reinforced Cement in Exhibition Decoration Project

NASA Astrophysics Data System (ADS)

Wang, Yao

2018-02-01

Through the study of GRC material and its application field, the aesthetic characteristics and functional characteristics of GRC materials are demonstrated. The decorative application and technology of GRC material in an art exhibition center are highlighted. The design, application and construction technology of GRC curtain wall and ceiling board in the interior and exterior decoration of art exhibition hall are discussed in detail. The unique advantages of GRC materials in exhibition engineering decoration are fully reflected. In practical design application, the application principle and method are summarized, and an application procedure is formed. The research proves that GRC materials in the art of building decoration engineering has an underrated advantage.

Materials for advanced rocket engine turbopump turbine blades

NASA Technical Reports Server (NTRS)

Chandler, W. T.

1985-01-01

A study program was conducted to identify those materials that will provide the greatest benefits as turbine blades for advanced liquid propellant rocket engine turbines and to prepare technology plans for the development of those materials for use in the 1990 through 1995 period. The candidate materials were selected from six classes of materials: single-crystal (SC) superalloys, oxide dispersion-strengthened (ODS) superalloys, rapid solidification processed (RSP) superalloys, directionally solidified eutectic (DSE) superalloys, fiber-reinforced superalloy (FRS) composites, and ceramics. Properties of materials from the six classes were compiled and evaluated and property improvements were projected approximately 5 years into the future for advanced versions of materials in each of the six classes.

Study and Behaviour of Prefabricated Composite Cladding

NASA Astrophysics Data System (ADS)

Sai Avinash, P.; Thiagarajan, N.; Santhi, A. S.

2017-07-01

The incessant population rise entailed for an expeditious construction at competitive prices that steered the customary path to the light weight structural components. This lead to construction of structural components using ferrocement. The load bearing structural cladding, sizing 3200x900x100 mm, is chosen for the study, which, is analyzed using the software ABAQUS 6.14 in accordance with the IS:875-87 Part1, IS:875-87 Part2, ACI 549R-97, ACI 318R-08 and NZS:3101-06 Part1 standards. The Ferrocement claddings (FCs) are fabricated to a scaled dimension of 400x115x38 mm. The light weight-high strength phenomena are corroborated by incorporating Glass Fibre Reinforced Polymer Laminates (GFRPL) of thickness 6mm, engineered with the aid of hand layup (wet layup) technique wielding epoxy resin, followed by curing under room temperature. The epoxy resin is employed for fastening ferrocement cladding with the Glass fiber reinforced polymer laminate, with the contemporary methodology. The compressive load carrying capacity of the amalgamated assembly, both in presence and absence of Glass Fibre Reinforced polymer laminates (GFRPL) on either side of Ferrocement cladding, has been experimented.

Reinforcement of nylon 6,6/nylon 6,6 grafted nanodiamond composites by in situ reactive extrusion.

PubMed

Choi, Eun-Yeob; Kim, Kiho; Kim, Chang-Keun; Kang, Eunah

2016-11-14

Nanodiamond (ND), an emerging new carbon material, was exploited to reinforce nylon 6,6 (PA66) polymer composites. Surface modified nanodiamonds with acyl chloride end groups were employed to chemically graft into PA66, enhancing the interfacial adhesion and thus the mechanical properties. The ND grafted PA66 (PA66-g-ND) reinforced PA66 composite prepared by in situ reactive extrusion exhibited increased tensile strength and modulus. The tensile strength and modulus of PA66/3 wt.% PA66-g-ND composites were enhanced by 11.6 and 20.8%, respectively when compared to those of the bare PA66 matrix. Even the PA66/pristine ND composites exhibited enhanced mechanical properties. The PA66-g-ND and the homogeneously dispersed PA66-g-ND in PA66 matrix were examined using X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy techniques. The mechanical properties and thermal conductivities of the nanodiamond incorporated PA66 composites were also explored. The enhanced mechanical properties and thermal conductivities of the PA66-g-ND/PA66 composites make them potential materials for new applications as functional engineered thermoplastics.

An Experimental Study on Strengthening of Reinforced Concrete Flexural Members using Steel Wire Mesh

NASA Astrophysics Data System (ADS)

Al Saadi, Hamza Salim Mohammed; Mohandas, Hoby P.; Namasivayam, Aravind

2017-01-01

One of the major challenges and contemporary research in the field of structural engineering is strengthening of existing structural elements using readily available materials in the market. Several investigations were conducted on strengthening of various structural components using traditional and advanced materials. Many researchers tried to enhance the reinforced concrete (RC) beams strength using steel plate, Glass and Carbon Fibre Reinforced Polymers (GFRP & CFRP). For the reason that high weight to the strength ratio and compatibility in strength between FRP composites and steel bars, steel plates and GFRP and CFRP composites are not used for strengthening works practically. Hence, in this present work the suitability of using wire mesh for the purpose of strengthening the RC flexural members is studied by conducting experimental works. New technique of strengthening system using wire mesh with a view to improve sectional properties and subsequently flexural strength of RC beams is adopted in this work. The results for experimental and theoretical analysis were compared and found that good correlation exists between them. The experimental results indicate that RC beams strengthened with steel wire mesh are easy technique for strengthening of existing flexural members.

Retrofitting of Reinforced Concrete Beams using Reactive Powder Concrete (RPC)

NASA Astrophysics Data System (ADS)

Karthik, S.; Sundaravadivelu, Karthik

2017-07-01

Strengthening of existing damaged structures is one of the leading studies in civil engineering. The purpose of retrofitting is to structurally treat the member with an aim to restore the structure to its original strength. The focus of this project is to study the behaviour of damaged Reinforced Concrete beam retrofitted with Reactive Powder Concrete (RPC) Overlay. Reinforced concrete beams of length 1200 mm, width 100 mm and depth 200 mm were casted with M30 grade of concrete in the laboratory and cured for 28 days. One beam is taken as control and are tested under two point loading to find out ultimate load. Remaining beams are subjected to 90 % ultimate load of control beams. The partially damaged beams are retrofitted with Reactive Powder Concrete Overlay at the full tension face of the beam and side overlay depends upon the respectable retrofitting techniques with 10 mm and 20 mm thick layer to find optimum. Materials like steel fibres are added to enhance the ductility by eliminating coarse particle for homogeneity of the structure. Finally, the modes of failure for retrofitted beams are analysed experimentally under two point loading & compared the results with Control beam.

Reinforcement of nylon 6,6/nylon 6,6 grafted nanodiamond composites by in situ reactive extrusion

NASA Astrophysics Data System (ADS)

Choi, Eun-Yeob; Kim, Kiho; Kim, Chang-Keun; Kang, Eunah

2016-11-01

Nanodiamond (ND), an emerging new carbon material, was exploited to reinforce nylon 6,6 (PA66) polymer composites. Surface modified nanodiamonds with acyl chloride end groups were employed to chemically graft into PA66, enhancing the interfacial adhesion and thus the mechanical properties. The ND grafted PA66 (PA66-g-ND) reinforced PA66 composite prepared by in situ reactive extrusion exhibited increased tensile strength and modulus. The tensile strength and modulus of PA66/3 wt.% PA66-g-ND composites were enhanced by 11.6 and 20.8%, respectively when compared to those of the bare PA66 matrix. Even the PA66/pristine ND composites exhibited enhanced mechanical properties. The PA66-g-ND and the homogeneously dispersed PA66-g-ND in PA66 matrix were examined using X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy techniques. The mechanical properties and thermal conductivities of the nanodiamond incorporated PA66 composites were also explored. The enhanced mechanical properties and thermal conductivities of the PA66-g-ND/PA66 composites make them potential materials for new applications as functional engineered thermoplastics.

Reinforcement of nylon 6,6/nylon 6,6 grafted nanodiamond composites by in situ reactive extrusion

PubMed Central

Choi, Eun-Yeob; Kim, Kiho; Kim, Chang-Keun; Kang, Eunah

2016-01-01

Nanodiamond (ND), an emerging new carbon material, was exploited to reinforce nylon 6,6 (PA66) polymer composites. Surface modified nanodiamonds with acyl chloride end groups were employed to chemically graft into PA66, enhancing the interfacial adhesion and thus the mechanical properties. The ND grafted PA66 (PA66-g-ND) reinforced PA66 composite prepared by in situ reactive extrusion exhibited increased tensile strength and modulus. The tensile strength and modulus of PA66/3 wt.% PA66-g-ND composites were enhanced by 11.6 and 20.8%, respectively when compared to those of the bare PA66 matrix. Even the PA66/pristine ND composites exhibited enhanced mechanical properties. The PA66-g-ND and the homogeneously dispersed PA66-g-ND in PA66 matrix were examined using X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy techniques. The mechanical properties and thermal conductivities of the nanodiamond incorporated PA66 composites were also explored. The enhanced mechanical properties and thermal conductivities of the PA66-g-ND/PA66 composites make them potential materials for new applications as functional engineered thermoplastics. PMID:27841314

A Progressive Damage Model for unidirectional Fibre Reinforced Composites with Application to Impact and Penetration Simulation

NASA Astrophysics Data System (ADS)

Kerschbaum, M.; Hopmann, C.

2016-06-01

The computationally efficient simulation of the progressive damage behaviour of continuous fibre reinforced plastics is still a challenging task with currently available computer aided engineering methods. This paper presents an original approach for an energy based continuum damage model which accounts for stress-/strain nonlinearities, transverse and shear stress interaction phenomena, quasi-plastic shear strain components, strain rate effects, regularised damage evolution and consideration of load reversal effects. The physically based modelling approach enables experimental determination of all parameters on ply level to avoid expensive inverse analysis procedures. The modelling strategy, implementation and verification of this model using commercially available explicit finite element software are detailed. The model is then applied to simulate the impact and penetration of carbon fibre reinforced cross-ply specimens with variation of the impact speed. The simulation results show that the presented approach enables a good representation of the force-/displacement curves and especially well agreement with the experimentally observed fracture patterns. In addition, the mesh dependency of the results were assessed for one impact case showing only very little change of the simulation results which emphasises the general applicability of the presented method.

Calculation of reinforced-concrete frame strength under a simultaneous static cross section load and a column lateral impact

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belov, Nikolay, E-mail: n.n.belov@mail.ru; Kopanitsa, Dmitry, E-mail: kopanitsa@mail.ru; Yugov, Alexey, E-mail: yugalex@mail.ru

When designing buildings with reinforced concrete that are planned to resist dynamic loads it is necessary to calculate this structural behavior under operational static and emergency impact and blast loads. Calculations of the structures under shock-wave loads can be performed by solving dynamic equations that do not consider static loads. Due to this fact the calculation of reinforced concrete frame under a simultaneous static and dynamic load in full 3d settings becomes a very non trivial and resource consuming problem. This problem can be split into two tasks. The first one is a shock-wave problem that can be solved usingmore » software package RANET-3, which allows solving the problem using finite elements method adapted for dynamic task. This method calculates strain-stress state of the material and its dynamic destruction, which is considered as growth and consolidation of micro defects under loading. On the second step the results of the first step are taken as input parameters for quasi static calculation of simultaneous static and dynamic load using finite elements method in AMP Civil Engineering-11.« less

Current status and recent research achievements in SiC/SiC composites

NASA Astrophysics Data System (ADS)

Katoh, Y.; Snead, L. L.; Henager, C. H.; Nozawa, T.; Hinoki, T.; Iveković, A.; Novak, S.; Gonzalez de Vicente, S. M.

2014-12-01

The silicon carbide fiber-reinforced silicon carbide matrix (SiC/SiC) composite system for fusion applications has seen a continual evolution from development a fundamental understanding of the material system and its behavior in a hostile irradiation environment to the current effort which is directed at a broad-based program of technology maturation program. In essence, over the past few decades this material system has steadily moved from a laboratory curiosity to an engineering material, both for fusion structural applications and other high performance application such as aerospace. This paper outlines the recent international scientific and technological achievements towards the development of SiC/SiC composite material technologies for fusion application and discusses future research directions. It also reviews the materials system in the larger context of progress to maturity as an engineering material for both the larger nuclear community and broader engineering applications.

Transmission Planning Analysis Tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

2015-06-23

Developed to solve specific problem: Assist transmission planning for regional transfers in interconnected power systems. This work was originated in a study for the U.S. Department of State, to recommend transmission reinforcements for the Central American regional system that interconnects 6 countries. Transmission planning analysis is currently performed by engineers with domainspecific and systemspecific knowledge without a unique methodology. The software codes of this disclosure assists engineers by defining systematic analysis procedures to help identify weak points and make decisions on transmission planning of regional interconnected power systems. Transmission Planning Analysis Tool groups PSS/E results of multiple AC contingency analysismore » and voltage stability analysis and QV analysis of many scenarios of study and arrange them in a systematic way to aid power system planning engineers or transmission operators in effective decision]making process or in the off]line study environment.« less

From the foundation act to the corporate culture of a BME teaching institute.

PubMed

Augustyniak, Ewa; Augustyniak, Piotr

2010-01-01

This paper describes the concept and application of the organizational culture of a BME teaching institute, based on the specificity of biomedical engineering. Selected values and behavioral patterns typical for this profession were endorsed to reinforce the mutual cooperation and understanding of students, university staff and employers as partners in the educational process. Besides of building a professional pride and reputation of the teaching institute, the corporate culture is proved to be useful in imposing of the attitudes required in future career of the biomedical engineer as a partner of a medic in his efforts aimed at the wellness and safety of the patient. Five years since the foundation of the Multidisciplinary School of engineering In Biomedicine we still do not have a quantitative measure of the educational outcome quality, nevertheless the presented idea may be very useful and worth sharing with all BME educators.

Mechanical and low-cycle fatigue behavior of stainless reinforcing steel for earthquake engineering applications

NASA Astrophysics Data System (ADS)

Zhou, Yihui; Ou, Yu-Chen; Lee, George C.; O'Connor, Jerome S.

2010-09-01

Use of stainless reinforcing steel (SRS) in reinforced concrete (RC) structures is a promising solution to corrosion issues. However, for SRS to be used in seismic applications, several mechanical properties need to be investigated. These include specified and actual yield strengths, tensile strengths, uniform elongations and low-cycle fatigue behavior. Three types of SRSs (Talley S24100, Talley 316LN and Talley 2205) were tested and the results are reported in this paper. They were compared with the properties of A706 carbon reinforcing steel (RS), which is typical for seismic applications, and MMFX II, which is a high strength, corrosion resistant RS. Low-cycle fatigue tests of the RS coupons were conducted under strain control with constant amplitude to obtain strain life models of the steels. Test results show that the SRSs have slightly lower moduli of elasticity, higher uniform elongations before necking, and better low-cycle fatigue performance than A706 and MMFX II. All five types of RSs tested satisfy the requirements of the ACI 318 code on the lower limit of the tensile to yield strength ratio. Except Talley 2205, the other four types of RSs investigated meet the ACI 318 requirement that the actual yield strength does not exceed the specified yield strength by more than 18 ksi (124 MPa). Among the three types of SRSs tested, Talley S24100 possesses the highest uniform elongation before necking, and the best low-cycle fatigue performance.

Global Failure Modes in High Temperature Composite Structures

NASA Technical Reports Server (NTRS)

Knauss, W. G.

1998-01-01

Composite materials have been considered for many years as the major advance in the construction of energy efficient aerospace structures. Notable advances have been made in understanding the special design considerations that set composites apart from the usual "isotropic" engineering materials such as the metals. As a result, a number of significant engineering designs have been accomplished. However, one shortcoming of the currently favored composites is their relatively unforgiving behavior with respect to failure (brittleness) under seemingly mild impact conditions and large efforts are underway to rectify that situation, much along the lines of introducing thermoplastic matrix materials. Because of their relatively more pronounced (thermo) viscoelastic behavior these materials respond with "toughness" in fracture situations. From the point of view of applications requiring material strength, this property is highly desirable. This feature impacts several important and distinct engineering problems which have been' considered under this grant and cover the 1) effect of impact damage on structural (buckling) stability of composite panels, the 2) effect of time dependence on the progression of buckling instabilities, and the 3) evolution of damage and fracture at generic thickness discontinuities in structures. The latter topic has serious implications for structural stability problems (buckling failure in reinforced shell structures) as well as failure progression in stringer-reinforced shell structures. This grant has dealt with these issues. Polymer "toughness" is usually associated with uncrosslinked or thermo-plastic polymers. But, by comparison with their thermoset counterparts they tend to exhibit more pronounced time dependent material behavior; also, that time dependence can occur at lower temperatures which places restriction in the high temperature use of these "newer and tougher" materials that are not quite so serious with the thermoset matrix materials. From a structural point of view the implications of this material behavior are potentially severe in that structural failure characteristics are no longer readily observed in short term qualification tests so characteristic for aerospace structures built from typical engineering metals.

Mechanical behavior of a cellulose-reinforced scaffold in vascular tissue engineering.

PubMed

Pooyan, Parisa; Tannenbaum, Rina; Garmestani, Hamid

2012-03-01

Scaffolds constitute an essential structural component in tissue engineering of a vascular substitute for small grafts by playing a significant role in integrating the overall tissue constructs. The microstructure and mechanical properties of such scaffolds are important parameters to promote further cellular activities and neo-tissue development. Cellulose nanowhiskers (CNWs), an abundant, biocompatible material, could potentially constitute an acceptable candidate in scaffolding of a tissue-engineered vessel. Inspired by the advantages of cellulose and its derivatives, we have designed a biomaterial comprising CNWs embedded in a matrix of cellulose acetate propionate to fabricate a fully bio-based scaffold. To ensure uniform distribution, CNWs were delicately extracted from a multi-stage process and dispersed in an acetone suspension prior to the composite fabrication. Comparable to carbon nanotubes or kevlar, CNWs impart significant strength and directional rigidity even at 0.2 wt% and almost double that at only 3.0 wt%. To ensure the accuracy of our experimental data and to predict the unusual reinforcing effect of CNWs in a cellulose-based composite, homogenization schemes such as the mean field approach and the percolation technique were also investigated. Based on these comparisons, the tendency of CNWs to interconnect with one another through strong hydrogen bonding confirmed the formation of a three-dimensional rigid percolating network, fact which imparted an excellent mechanical stability to the entire structure at such low filler contents. Hence, our fibrous porous microstructure with improved mechanical properties could introduce a potential scaffold to withstand the physiological pressure and to mimic the profile features of native extracellular matrix in a human vessel. We believe that our nanohybrid design not only could expand the biomedical applications of renewable cellulose-based materials but also could provide a potential scaffold candidate in tissue engineering of small diameter grafts. Copyright © 2011 Elsevier Ltd. All rights reserved.

Aerospace Plane Technology, Research and Development Efforts in Europe

DTIC Science & Technology

1991-07-25

to conventional titanium alloys. Moreover, ti- aluminide has one-half the weight of the material previously used at these high temperatures. Real Gas...for the engine’s blades , turbine blisk (a turbine disk with integral blades ), Page 44 GAO/NSIAID-91-194 Aerospace Plane Technology Chapter 3 European...X-30 fuselage section from silicon carbide-reinforced titanium and manufactured an X-30 fuel tank from a graphite-polyamide composite. Although

NCEL (Naval Civil Engineering Laboratory) Quarterly Abstracts of Technical Documents, 1 April to 30 June 1987.

DTIC Science & Technology

1987-06-30

release; distribution unlimited. 87 8 3075 TABLE OF CONTENTS page TECHNICAL NOTES N-1764 Validation of Nitronic 33 in Reinforced and Prestressed...TECHNICAL WES K- 1764 Validation of Nitrovic 33 In Reeinforced and Prestressed Concrete, Apr 1987, James F. Jenkins (public release) Nitronic 33...prestressing strand are not acceptable. Before Nitronic 33 stainless steel prestressed concrete waterfront structures were constructed, it was necessary to

Recent Advances in the Edge-Function Method 1979-1980

DTIC Science & Technology

1980-07-30

the residuals are within the limits within which an engineer can specify the boundary conditions of the problem, then the corresponding Mathematical ...truncation lvel . The consistent preference shown by the solver routine for verteA functions as opposed to polar functions reinforces the expectations of...Accordingly,each solution zr_.-4_des a Mathematical Model for the given physical problem- R.M.S. values provide a practical criterion for the enai--er to

Advanced Composites for Air and Ground Vehicles

DTIC Science & Technology

2015-08-01

Engineering A, 429: 225–235. [2] Sharma, S. (2010). “Process development issues of glass-carbon hybrid- reinforced polymer composite wind turbine blades...with numerous possibilities including “zero- slip ” behavior, reduced/delayed delaminations under load, and enhanced load-carrying capacities relative to...pads having a Shore-A durometer of 55 and thickness of 3 mm were glued to the loading block to prevent slipping . The loading and support bars were

Environmental Assessment (EA) for the Comprehensive Range Plan (CRP), Melrose Air Force Range (AFR), New Mexico

DTIC Science & Technology

2011-07-01

11,674 sq ft C-130 maintenance hangar with reinforced concrete footings, a foundation and footing slab, a structural steel frame, insulated metal...regional farming output significantly; however, it could potentially have a detrimental effect to the lessee. Environmental Justice – There are no...Facility – Construct a pre-engineered one story steel framed structure including the necessary concrete foundations to support the building.  SOF

A Nonlinear Three-Dimensional Micromechanics Model for Fiber-Reinforced Laminated Composites

DTIC Science & Technology

1993-11-01

Interfacial Properties Employed for the SCS6/Ti-15-3 Composite ......................... 150 11. Constants Employed for the LLFM Predictions of Quasi...Region m Matrix Property or Mean of the Interfacial Stress Distribution ml, m2, m3 Signifies Matrix Region n Normal to Interface r Signifies Equation...usage of the new class of titanium based com- posites in advanced aerospace structures and engines such as are targeted for the advanced tactical fighter

Survey of Laboratories and Implementation of the Federal Defense Laboratory Diversification Program. Annex A. Department of the Army Domestic Technology Transfer

DTIC Science & Technology

1993-11-01

Recover Nitramine (Yxidizers from Solid Propellants Using Liquid Ammonia * Co~ial Engine for Ducted Hybrid , and Gel BI-propu~uion Systems S ltravolet...Surface Optical Testing Device * Electron Beam Driven Negative Ion Source * Method of Manufacturing Hybrid Fber-Reinforced Composite Nozzle Materials...Modeling Software FRED Partner I ty * Class VDrnng Simulation Parow. Academia * Combustion and Tribology Partne. Academia * Hybrid Electric Drive/High

CRAG (Composite Research Advisory Group) Test Methods for the Measurement of the Engineering Properties of Fibre Reinforced Plastics

DTIC Science & Technology

1988-02-01

Environmental effects Method 900 - Background information on environmental effects 78 Method 901 - Method of assessment of diffusivity properties of fibre... environmental conditioning. Strain gauges can sometimes fail during prolonged fatigue testing, and it is therefore prudent to undertake a secondary check...fibre volume fraction of the laminate as described in section 1000. (iv) The environmental history of the specimen prior to test. (v) The environmental

Hybrid Carbon-Glass Fiber/Toughened Epoxy Thick Composite Joints Subject to Drop-Weight and Ballistic Impacts

DTIC Science & Technology

2007-12-01

and thermal properties of composites. Ch. 3 in Fibre Composite Hybrid Materials. Hancox NL (Ed). Applied Science Publishers, London, 1981. 95...Kretsis G. A review of the tensile, compressive, flexural and shear properties of hybrid fibre -reinforced plastics. Composites 1987; 18: 13-23. 96...advanced degrees in engineering. Page 3 3. Technical Background 3.1: Usage of composites in Army ground vehicles The use of high

Polymer-based composites for aerospace: An overview of IMAST results

NASA Astrophysics Data System (ADS)

Milella, Eva; Cammarano, Aniello

2016-05-01

This paper gives an overview of technological results, achieved by IMAST, the Technological Cluster on Engineering of Polymeric Composite Materials and Structures, in the completed Research Projects in the aerospace field. In this sector, the Cluster developed different solutions: lightweight multifunctional fiber-reinforced polymer composites for aeronautic structures, advanced manufacturing processes (for the optimization of energy consumption and waste reduction) and multifunctional components (e.g., thermal, electrical, acoustic and fire resistance).

Long-term Isothermal Aging Effects on Weight Loss, Compression Properties, and Dimensions of T650-35 Fabric-reinforced PMR-15 Composites-data

NASA Technical Reports Server (NTRS)

Bowles, Kenneth J.; Tsuji, Luis; Kamvouris, John; Roberts, Gary D.

2003-01-01

A cooperative program was conducted with the General Electric Aircraft Engines plant in Evendale, Ohio, to study the effects of long-term isothermal aging at elevated temperatures on compression and thermal durability properties of T650 35 fabric-reinforced PMR 15 composites. This degradation study was conducted over an approximate time period of 3 1/2 yr. The aging temperatures were 204, 260, 288, 316, and 343 C. Specimens of different dimensions were evaluated. Specimens with ratios of the cut edge to total surface area of 0.03 to 0.89 were fabricated and aged. The aged and unaged specimens were tested in compression as specified in Test Method for Compressive Properties of Rigid Plastics (ASTM D695M). Thickness changes, degraded surface layer growth, weight loss, and failure modes were monitored and recorded. All property changes were thickness dependent.

Application of Hydrophilic Silanol-Based Chemical Grout for Strengthening Damaged Reinforced Concrete Flexural Members

PubMed Central

Ju, Hyunjin; Lee, Deuck Hang; Cho, Hae-Chang; Kim, Kang Su; Yoon, Seyoon; Seo, Soo-Yeon

2014-01-01

In this study, hydrophilic chemical grout using silanol (HCGS) was adopted to overcome the performance limitations of epoxy materials used for strengthening existing buildings and civil engineering structures. The enhanced material performances of HCGS were introduced, and applied to the section enlargement method, which is one of the typical structural strengthening methods used in practice. To evaluate the excellent structural strengthening performance of the HCGS, structural tests were conducted on reinforced concrete beams, and analyses on the flexural behaviors of test specimens were performed by modified partial interaction theory (PIT). In particular, to improve the constructability of the section enlargement method, an advanced strengthening method was proposed, in which the precast panel was directly attached to the bottom of the damaged structural member by HCGS, and the degree of connection of the test specimens, strengthened by the section enlargement method, were quantitatively evaluated by PIT-based analysis. PMID:28788708

Studies on mechanical properties of graphene based hybrid composites reinforced with kenaf/glass fiber

NASA Astrophysics Data System (ADS)

Kumar, S. C. Ramesh; Shivanand, H. K.; Vidayasagar, H. N.; Nagabhushan, V.

2018-04-01

The polymer composites are developed with natural fibers and fillers as a alternate material for some of the engineering applications in the field of automobiles and domestic purposes are being investigated. The natural fiber composites such as banana, sisal, jute, coir, kenaf and hemp polymer composites appear more effective due to their lightweight, higher specific strength, biodegradable and cost is low. The main objective is to prepare the Kenaf/Glass fiber hybrid composite filled with graphene as nano filler and to investigate the mechanical properties of hybrid composites. The different types of hybrid composites laminates are fabricated without filler, 0.5, 1 & 1.5Wt % of graphene by using kenaf and glass fiber as reinforcing material with epoxy resin. The specimen were prepared as per the ASTM standards and results shows that the mixing of graphene in epoxy resin improves the mechanical properties of hybrid composites.

Effects of different crumb rubber sizes on the flowability and compressive strength of hybrid fibre reinforced ECC

NASA Astrophysics Data System (ADS)

Khed, Veerendrakumar C.; Mohammed, Bashar S.; Fadhil Nuruddin, Muhd

2018-04-01

The different sizes of crumb rubber have been used to investigate the effects on flowability and the compressive strength of the hybrid fibre reinforced engineered cementitious composite. Two sizes of crumb rubber 30 mesh and 1 to 3mm were used in partial replacement with the fine aggregate up to 60%. The experimental study was carried out through mathematical and statistical analysis by response surface methodology (RSM) using the Design Expert software. The response models have been developed and the results were validated by analysis of variance (ANOVA). It was found that finer sized crumb rubber inclusion had produced better workability and higher compressive strength when compared to the larger size and it was concluded that crumb rubber has negative effect on compressive strength and positive effect on workability. The optimization results are found to an approximately good agreement with the experimental results.

Microstructural and Mechanical Aspects of Reinforcement Welds for Lightweight Components Produced by Friction Hydro Pillar Processing

NASA Astrophysics Data System (ADS)

Pinheiro, Gustavo; dos Santos, Jorge; Hort, Norbert; Kainer, Karl Ulrich

The development of new creep resistant and cost effective die casting magnesium alloys such as AE, MRI, MEZ, ACM, AXJ, AJ, WE have emerged as an alternative to fulfil the actual demands in structural relevant applications as engines blocks, gear and converter boxes. However, magnesium components are in most of the cases screwed with aluminium and steel bolts, which lead the screwed joint to lose the preload force due to relaxation. This barrier limits thus the broad use of magnesium within this segment and should somehow find an adequate solution to be implemented and to help overcoming this limitation. In this context Friction Welding (FW) and particularly Friction Hydro Pillar Processing (FHPP), which can be described as a drill and fill process, appears as an alternative to widespread the use of magnesium. In this context, FHPP is intended to be used to locally reinforce mechanical fastened magnesium components.

Structural characterization of high temperature composites

NASA Technical Reports Server (NTRS)

Mandell, J. F.; Grande, D. H.

1991-01-01

Glass, ceramic, and carbon matrix composite materials have emerged in recent years with potential properties and temperature resistance which make them attractive for high temperature applications such as gas turbine engines. At the outset of this study, only flexural tests were available to evaluate brittle matrix composites at temperatures in the 600 to 1000 C range. The results are described of an ongoing effort to develop appropriate tensile, compression, and shear test methods for high temperature use. A tensile test for unidirectional composites was developed and used to evaluate the properties and behavior of ceramic fiber reinforced glass and glass-ceramic matrix composites in air at temperatures up to 1000 C. The results indicate generally efficient fiber reinforcement and tolerance to matrix cracking similar to polymer matrix composites. Limiting properties in these materials may be an inherently very low transverse strain to failure, and high temperature embrittlement due to fiber/matrix interface oxidation.

Thermal Analysis of Reinforced Concrete Tank for Conditioning Wood by FEM Method

NASA Astrophysics Data System (ADS)

Błaszczyński, Tomasz; Babiak, Michał; Wielentejczyk, Przemysław

2017-10-01

The article introduces the analysis of a RC tank for conditioning wood carried out using the FEM (Finite Element Method). A temperature gradient distribution increase resulting from the influence of hot liquid filling the tank was defined. Values of gradients in border sections of the tank walls and the bottom were defined on the basis of the isotherm method. The obtained results were compared with empirical formulas from literature. Strength analyses were also carried out. Additionally, the problematic aspects of elongated monolithic tanks for liquids were introduced, especially regarding large temperature gradients and the means of necessary technical solutions. The use of the FEM method for designing engineering objects is, nowadays, an irreplaceable solution. In the case of the discussed tank, a spatial model of the construction mapping its actual performance was constructed in order to correctly estimate the necessary dimensions of wall and bottom sections, as well as reinforcement.

Application of Hydrophilic Silanol-Based Chemical Grout for Strengthening Damaged Reinforced Concrete Flexural Members.

PubMed

Ju, Hyunjin; Lee, Deuck Hang; Cho, Hae-Chang; Kim, Kang Su; Yoon, Seyoon; Seo, Soo-Yeon

2014-06-23

In this study, hydrophilic chemical grout using silanol (HCGS) was adopted to overcome the performance limitations of epoxy materials used for strengthening existing buildings and civil engineering structures. The enhanced material performances of HCGS were introduced, and applied to the section enlargement method, which is one of the typical structural strengthening methods used in practice. To evaluate the excellent structural strengthening performance of the HCGS, structural tests were conducted on reinforced concrete beams, and analyses on the flexural behaviors of test specimens were performed by modified partial interaction theory (PIT). In particular, to improve the constructability of the section enlargement method, an advanced strengthening method was proposed, in which the precast panel was directly attached to the bottom of the damaged structural member by HCGS, and the degree of connection of the test specimens, strengthened by the section enlargement method, were quantitatively evaluated by PIT-based analysis.

Creep and Stress-strain Behavior After Creep from Sic Fiber Reinforced, Melt-infiltrated Sic Matrix Composites

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Pujar, Vijay

2004-01-01

Silicon carbide fiber (Hi-Nicalon Type S, Nippon Carbon) reinforced silicon carbide matrix composites containing melt-infiltrated Si were subjected to creep at 1315 C for a number of different stress conditions, This study is aimed at understanding the time-dependent creep behavior of CMCs for desired use-conditions, and also more importantly, how the stress-strain response changes as a result of the time-temperature-stress history of the crept material. For the specimens that did not rupture, fast fracture experiments were performed at 1315 C or at room temperature immediately following tensile creep. In many cases, the stress-strain response and the resulting matrix cracking stress of the composite change due to stress-redistribution between composite constituents during tensile creep. The paper will discuss these results and its implications on applications of these materials for turbine engine components.

Feasibility Study for Casting of High Temperature Refractory Superalloy Composites

NASA Technical Reports Server (NTRS)

Lee, Jonathan A.

1998-01-01

Abstract This study investigated the feasibility of using conventional casting technique to fabricate refractory wires reinforced superalloy composites. These composites were being developed for advanced rocket engine turbine blades and other high temperature applications operating up to 2000 F. Several types of refractory metal wires such as W- Th, W-Re, Mo-Hf-C and W-HF-C reinforced waspaloy were experimentally cast and heat treated at 2000 F up to 48 hrs. Scanning electron microscope analysis was conducted in regions adjacent to the wire-matrix interface to determine the reaction zone and chemical compatibility resulting from material interdiffusion. It was concluded that fabrication using conventional casting may be feasible because the wire-matrix reaction zone thickness was comparable to similar composites produced by arc-sprayed monotape with hot isostatic pressing technique, Moreover, it was also found that the chemical compatibility could be improved significantly through a slight modification of the superalloy matrix compositions.

Analysis/design of strip reinforced random composites (strip hybrids)

NASA Technical Reports Server (NTRS)

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

1978-01-01

Advanced analysis methods and composite mechanics were applied to a strip-reinforced random composite square panel with fixed ends to illustrate the use of these methods for the a priori assessment of the composite panel when subjected to complex loading conditions. The panel was assumed to be of E-glass random composite. The strips were assumed to be of three advanced unidirectional composites to cover a range of low, intermediate, and high modulus stiffness. The panels were assumed to be subjected to complex loadings to assess their adequacy as load-carrying members in auto body, aircraft engine nacelle and windmill blade applications. The results show that strip hybrid panels can be several times more structurally efficient than the random composite base materials. Some of the results are presented in graphical form and procedures are described for use of these graphs as guides for preliminary design of strip hybrids.

Programmed Nanomaterial Assemblies in Large Scales: Applications of Synthetic and Genetically- Engineered Peptides to Bridge Nano-Assemblies and Macro-Assemblies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsui, Hiroshi

Work is reported in these areas: Large-scale & reconfigurable 3D structures of precise nanoparticle assemblies in self-assembled collagen peptide grids; Binary QD-Au NP 3D superlattices assembled with collagen-like peptides and energy transfer between QD and Au NP in 3D peptide frameworks; Catalytic peptides discovered by new hydrogel-based combinatorial phage display approach and their enzyme-mimicking 2D assembly; New autonomous motors of metal-organic frameworks (MOFs) powered by reorganization of self-assembled peptides at interfaces; Biomimetic assembly of proteins into microcapsules on oil-in-water droplets with structural reinforcement via biomolecular recognition-based cross-linking of surface peptides; and Biomimetic fabrication of strong freestanding genetically-engineered collagen peptide filmsmore » reinforced by quantum dot joints. We gained the broad knowledge about biomimetic material assembly from nanoscale to microscale ranges by coassembling peptides and NPs via biomolecular recognition. We discovered: Genetically-engineered collagen-like peptides can be self-assembled with Au NPs to generate 3D superlattices in large volumes (> μm{sup 3}); The assembly of the 3D peptide-Au NP superstructures is dynamic and the interparticle distance changes with assembly time as the reconfiguration of structure is triggered by pH change; QDs/NPs can be assembled with the peptide frameworks to generate 3D superlattices and these QDs/NPs can be electronically coupled for the efficient energy transfer; The controlled assembly of catalytic peptides mimicking the catalytic pocket of enzymes can catalyze chemical reactions with high selectivity; and, For the bacteria-mimicking swimmer fabrication, peptide-MOF superlattices can power translational and propellant motions by the reconfiguration of peptide assembly at the MOF-liquid interface.« less

Finite element analyses for seismic shear wall international standard problem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Y.J.; Hofmayer, C.H.

Two identical reinforced concrete (RC) shear walls, which consist of web, flanges and massive top and bottom slabs, were tested up to ultimate failure under earthquake motions at the Nuclear Power Engineering Corporation`s (NUPEC) Tadotsu Engineering Laboratory, Japan. NUPEC provided the dynamic test results to the OECD (Organization for Economic Cooperation and Development), Nuclear Energy Agency (NEA) for use as an International Standard Problem (ISP). The shear walls were intended to be part of a typical reactor building. One of the major objectives of the Seismic Shear Wall ISP (SSWISP) was to evaluate various seismic analysis methods for concrete structuresmore » used for design and seismic margin assessment. It also offered a unique opportunity to assess the state-of-the-art in nonlinear dynamic analysis of reinforced concrete shear wall structures under severe earthquake loadings. As a participant of the SSWISP workshops, Brookhaven National Laboratory (BNL) performed finite element analyses under the sponsorship of the U.S. Nuclear Regulatory Commission (USNRC). Three types of analysis were performed, i.e., monotonic static (push-over), cyclic static and dynamic analyses. Additional monotonic static analyses were performed by two consultants, F. Vecchio of the University of Toronto (UT) and F. Filippou of the University of California at Berkeley (UCB). The analysis results by BNL and the consultants were presented during the second workshop in Yokohama, Japan in 1996. A total of 55 analyses were presented during the workshop by 30 participants from 11 different countries. The major findings on the presented analysis methods, as well as engineering insights regarding the applicability and reliability of the FEM codes are described in detail in this report. 16 refs., 60 figs., 16 tabs.« less

Fiber-optic sensor applications in civil and geotechnical engineering

NASA Astrophysics Data System (ADS)

Habel, Wolfgang R.; Krebber, Katerina

2011-09-01

Different types of fiber-optic sensors based on glass or polymeric fibers are used to evaluate material behavior or to monitor the integrity and long-term stability of load-bearing structure components. Fiber-optic sensors have been established as a new and innovative measurement technology in very different fields, such as material science, civil engineering, light-weight structures, geotechnical areas as well as chemical and high-voltage substations. Very often, mechanical quantities such as deformation, strain or vibration are requested. However, measurement of chemical quantities in materials and structure components, such as pH value in steel reinforced concrete members also provides information about the integrity of concrete structures. A special fiber-optic chemical sensor for monitoring the alkaline state (pH value) of the cementitious matrix in steel-reinforced concrete structures with the purpose of early detection of corrosion-initiating factors is described. The paper presents the use of several fiber-optic sensor technologies in engineering. One example concerns the use of highly resolving concrete-embeddable fiber Fabry-Perot acoustic emission (AE) sensors for the assessment of the bearing behaviour of large concrete piles in existing foundations or during and after its installation. Another example concerns fiber Bragg grating (FBG) sensors attached to anchor steels (micro piles) to measure the strain distribution in loaded soil anchors. Polymer optical fibers (POF) can be — because of their high elasticity and high ultimate strain — well integrated into textiles to monitor their deformation behaviour. Such "intelligent" textiles are capable of monitoring displacement of soil or slopes, critical mechanical deformation in geotechnical structures (dikes, dams, and embankments) as well as in masonry structures during and after earthquakes.

Scenario based seismic hazard assessment and its application to the seismic verification of relevant buildings

NASA Astrophysics Data System (ADS)

Romanelli, Fabio; Vaccari, Franco; Altin, Giorgio; Panza, Giuliano

2016-04-01

The procedure we developed, and applied to a few relevant cases, leads to the seismic verification of a building by: a) use of a scenario based neodeterministic approach (NDSHA) for the calculation of the seismic input, and b) control of the numerical modeling of an existing building, using free vibration measurements of the real structure. The key point of this approach is the strict collaboration, from the seismic input definition to the monitoring of the response of the building in the calculation phase, of the seismologist and the civil engineer. The vibrometry study allows the engineer to adjust the computational model in the direction suggested by the experimental result of a physical measurement. Once the model has been calibrated by vibrometric analysis, one can select in the design spectrum the proper range of periods of interest for the structure. Then, the realistic values of spectral acceleration, which include the appropriate amplification obtained through the modeling of a "scenario" input to be applied to the final model, can be selected. Generally, but not necessarily, the "scenario" spectra lead to higher accelerations than those deduced by taking the spectra from the national codes (i.e. NTC 2008, for Italy). The task of the verifier engineer is to act so that the solution of the verification is conservative and realistic. We show some examples of the application of the procedure to some relevant (e.g. schools) buildings of the Trieste Province. The adoption of the scenario input has given in most of the cases an increase of critical elements that have to be taken into account in the design of reinforcements. However, the higher cost associated with the increase of elements to reinforce is reasonable, especially considering the important reduction of the risk level.

A Route for Polymer Nanocomposites with Engineered Electrical Conductivity and Percolation Threshold

PubMed Central

Kalaitzidou, Kyriaki; Fukushima, Hiroyuki; Drzal, Lawrence T.

2010-01-01

Polymer nanocomposites with engineered electrical properties can be made by tuning the fabrication method, processing conditions and filler’s geometric and physical properties. This work focuses on investigating the effect of filler’s geometry (aspect ratio and shape), intrinsic electrical conductivity, alignment and dispersion within the polymer, and polymer crystallinity, on the percolation threshold and electrical conductivity of polypropylene based nanocomposites. The conductive reinforcements used are exfoliated graphite nanoplatelets, carbon black, vapor grown carbon fibers and polyacrylonitrile carbon fibers. The composites are made using melt mixing followed by injection molding. A coating method is also employed to improve the nanofiller’s dispersion within the polymer and compression molding is used to alter the nanofiller’s alignment.

Experimental study on the connection property of full-scale composite member

NASA Astrophysics Data System (ADS)

Panpan, Cao; Qing, Sun

2018-01-01

The excellent properties of composite result in its increasingly application in electric power construction, however there are less experimental studies on full-scale composite member connection property. Full-scale experiments of the connection property between E-glass fiber/epoxy reinforced polymer member and steel casing in practical engineering have been conducted. Based on the axial compression test of the designed specimens, the failure process and failure characteristics were observed, the load-displacement curves and strain distribution of the specimens were obtained. The finite element analysis was used to get the tensile connection strength of the component. The connection property of the components was analyzed to provide basis of the casing connection of GFRP application in practical engineering.

Advanced Environmental Barrier Coatings Developed for SiC/SiC Composite Vanes

NASA Technical Reports Server (NTRS)

Lee, Kang N.; Fox, Dennis S.; Eldridge, Jeffrey I.; Zhu, Dongming; Bansal, Narottam P.; Miller, Robert A.

2003-01-01

Ceramic components exhibit superior high-temperature strength and durability over conventional component materials in use today, signifying the potential to revolutionize gas turbine engine component technology. Silicon-carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC/SiC CMCs) are prime candidates for the ceramic hotsection components of next-generation gas turbine engines. A key barrier to the realization of SiC/SiC CMC hot-section components is the environmental degradation of SiC/SiC CMCs in combustion environments. This is in the form of surface recession due to the volatilization of silica scale by water vapor. An external environmental barrier coating (EBC) is a logical approach to achieve protection and long-term durability.

Effect of the tapered end of a FRP plate on the interfacial stresses in a strengthened beam used in civil engineering applications

NASA Astrophysics Data System (ADS)

Mahi, B. E.; Benrahou, K. H.; Belakhdar, Kh.; Tounsi, A.; Bedia, E. A. Adda

2014-09-01

The interfacial stresses of a beam strengthened with a FRP plate, which is widely employed in the civil engineering for rehabilitation and retrofitting of conventional structures, is investigated. An important feature of the reinforced beam is significant stress concentrations in the adhesive at the ends of the FRP plate. To reduce these interfacial stresses, a FRP plate with a tapered end is often used. The finite-difference method is utilized in this work to predict the distribution of interfacial stresses in beams strengthened with a FRP plate having a tapered end. Numerical results from the analysis are presented to demonstrate the advantages of using tapers in the design of strengthened beams.

Materials review for improved automotive gas turbine engine. [superalloys, refractory alloys, and ceramics

NASA Technical Reports Server (NTRS)

Belleau, C.; Ehlers, W. L.; Hagen, F. A.

1978-01-01

The potential role of superalloys, refractory alloys, and ceramics in the hottest sections of engines operating with turbine inlet temperatures as high as 1370 C is examined. The convential superalloys, directionally solidified eutectics, oxide dispersion strenghened alloys, and tungsten fiber reinforced superalloys are reviewed and compared on the basis of maximum turbine blade temperature capability. Improved high temperature protective coatings and special fabrication techniques for these advanced alloys are discussed. Chromium, columbium, molybdenum, tantalum, and tungsten alloys are also reviewed. Molbdenum alloys are found to be the most suitable for mass produced turbine wheels. Various forms and fabrication processes for silicon nitride, silicon carbide, and SIALON's are investigated for use in highstress and medium stress high temperature environments.

Encouraging the pursuit of advanced degrees in science and engineering: Top-down and bottom-up methodologies

NASA Technical Reports Server (NTRS)

Maddox, Anthony B.; Smith-Maddox, Renee P.; Penick, Benson E.

1989-01-01

The MassPEP/NASA Graduate Research Development Program (GRDP) whose objective is to encourage Black Americans, Mexican Americans, American Indians, Puerto Ricans, and Pacific Islanders to pursue graduate degrees in science and engineering is described. The GRDP employs a top-down or goal driven methodology through five modules which focus on research, graduate school climate, technical writing, standardized examinations, and electronic networking. These modules are designed to develop and reinforce some of the skills necessary to seriously consider the goal of completing a graduate education. The GRDP is a community-based program which seeks to recruit twenty participants from a pool of Boston-area undergraduates enrolled in engineering and science curriculums and recent graduates with engineering and science degrees. The program emphasizes that with sufficient information, its participants can overcome most of the barriers perceived as preventing them from obtaining graduate science and engineering degrees. Experience has shown that the top-down modules may be complemented by a more bottom-up or event-driven methodology. This approach considers events in the academic and professional experiences of participants in order to develop the personal and leadership skills necessary for graduate school and similar endeavors.

Comportement dynamique d'alliages a memoire de forme et application aux composites-AMF

NASA Astrophysics Data System (ADS)

de Santis, Silvio

Meeting current industrial, governmental and international standards regarding vibration and noise levels is a challenging task facing many engineers. These specifications are present in just about all fields of engineering, from aerospace to marine transportation, from automotive to railway transportation, from computer equipment to industrial working environments. An appropriate use of the remarkable properties of high damping metals (HIDAMETS) and shape memory alloy (SMA) reinforced composites emerges as a possible solution to these problems. Among many obstacles to overcome in developing such a technology, the implementation of reliable and adequate characterization techniques to determine dynamic properties of these materials appears to be of prime importance. The research efforts presented in this thesis are aimed at developing advanced techniques to characterize the dynamic behavior of HIDAMETS and SMA reinforced composites. These characterization results lead to the enhancement of numerical (finite element) and/or analytical methods for the simulation of dynamic responses of structures made of these materials. In particular, the research work has focused on three themes: the numerical and experimental validation of applying a characterization procedure developed for traditional composites to SMA reinforced composites; the development of a test bench for uniaxial hysteresis characterization of HIDAMETS in the medium frequency range; the hysteresis characterization and modeling of manganese copper (MnCu) and nickel titanium samples. The results obtained in the course of these efforts show that the characterization technique developed for traditional composites at the University of Brussels is sufficiently precise to successfully predict natural frequencies of complex SMA reinforced composite structures. Using the characterization to predict structural damping ratios, we observe a bias error in the prediction with respect to experimental results although the relative values between modes are consistent. Regarding the development of the test bench for uniaxial hysteresis characterization of HIDAMETS, results suggest that with the introduction of a few minor enhancements and with particular experimental precautions, the test bench can play an important role in characterizing HIDAMETS dynamic properties at various frequencies and strain amplitudes and in understanding micro mechanical mechanisms responsible for energy dissipation. Finally, uniaxial hysteresis loops and related parameters have been obtained with MnCu and NiTi samples. A material model based on dual kriging interpolation that expresses the tangent stiffness along these hysteresis loops as a function of strain and strain amplitude has also been developed.

Development of Fiber Reinforced Track Pad Materials

DTIC Science & Technology

1986-04-01

Transfer and Vulcanization of Rubber , I.R.I. Monograph, Elsevier, 1971. 12 Bergstrom, E.W., " Wear Resistant Rubber Tank Track Pads," Rock Island Arsenal...Fracture Mechanics to Rubber Articles, Including Tyres ," Phil. Trans. R. Soc. Lond. A299,,189-202 (1981). 10 Gent, Fielding-Russell, Livingston, and...System for Rubber Bonded to Brass-Plated Steel Tyre Cord," NR Technology, vol 11, Part 2, 1980, pp 21-27. 16 Lindley, P.B., Engineering Design with

In Situ Repair of Deteriorated Concrete in Hydraulic Structures: Feasibility Study

DTIC Science & Technology

1987-05-01

because of its severe deterioration. Examination of the structure had revealed extensive cracking in the beams , columns , and walls as well as pockets of...used extensively in hydraulic structures, such as dams, spill- ways, lock chambers, and bridge support columns and piers. The Corps of Engineers...Figure 6. Repair of crack by post reinforcement. lli FORM KEY WITH PRECAST CONCRETE OR MORTAR PLUGS SET IN BITI.MEN, HoLE DRILLED IN STEM OF WALL

PBF Reactor Building (PER620). Camera facing southeast in second basement. ...

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

PBF Reactor Building (PER-620). Camera facing southeast in second basement. Round form and reinforcing steel surround reactor vessel pit, which will be heavily shielded by several feet of concrete. Block-out is for door to sub-pile room. Rectangular form and rebar beyond pit is for canal wall. Photographer: John Capek. Date: March 10, 1967. INEEL negative no. 67-1643 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

9. Photocopy of photograph original print located in collection of ...

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

9. Photocopy of photograph original print located in collection of William H. Caruthers, Jr., Richmond, Virginia, and loaned by Susan A. Harter, Tempe, Arizona. Photographer assumed to be William H. Caruthers, Sr., assistant (construction) engineer for the Ash Avenue Bridge, 1912 VIEW OF ASH AVENUE BRIDGE UNDER CONSTRUCTION, LOOKING NORTH, SHOWING STEEL REINFORCEMENT IN DECK BEFORE PLACEMENT OF CONCRETE - Ash Avenue Bridge, Spanning Salt River at Foot of Ash Avenue, Tempe, Maricopa County, AZ

Extending the Performance of Net Shape Molded Fiber Reinforced Polymer Composite Valves for Use in Internal Combustion Engines

DTIC Science & Technology

2007-06-01

management has been of increasingly significant importance. The combination of conventional materials and heat pipes have been applied in designs to take...chemical heat exchangers 87. In another spacecraft application, a carbon fiber face sheets with aluminum heat pipes embedded in an aluminum honeycomb...core were developed to replace an older all aluminum design. The heat pipes use ammonia as the working fluid. The new design improved thermal performance

Resources: NASA for entrepreneurs

NASA Technical Reports Server (NTRS)

Jannazo, Mary Ann

1988-01-01

The services of NASA's Technology Utilization Program are detailed and highlights of spinoff products in various stages of completion are described. Areas discussed include: Stirling engines for automotive applications, klystron tubes used to reduce power costs at UHF television stations, sports applications of riblet film (e.g., boat racing), reinforced plastic for high-temperature applications, coating technology appropriate for such applications similar to the renovation of the Statue of Liberty, and medical uses of fuel pump technology (e.g., heart pumps).

Enhancing the Biomechanical Performance of Anisotropic Nanofibrous Scaffolds in Tendon Tissue Engineering: Reinforcement with Cellulose Nanocrystals.

PubMed

Domingues, Rui M A; Chiera, Silvia; Gershovich, Pavel; Motta, Antonella; Reis, Rui L; Gomes, Manuela E

2016-06-01

Anisotropically aligned electrospun nanofibrous scaffolds based on natural/synthetic polymer blends have been established as a reasonable compromise between biological and biomechanical performance for tendon tissue engineering (TE) strategies. However, the limited tensile properties of these biomaterials restrict their application in this field due to the load-bearing nature of tendon/ligament tissues. Herein, the use of cellulose nanocrystals (CNCs) as reinforcing nanofillers in aligned electrospun scaffolds based on a natural/synthetic polymer blend matrix, poly-ε-caprolactone/chitosan (PCL/CHT) is reported. The incorporation of small amounts of CNCs (up to 3 wt%) into tendon mimetic nanofiber bundles has a remarkable biomaterial-toughing effect (85% ± 5%, p < 0.0002) and raises the scaffolds mechanical properties to tendon/ligament relevant range (σ = 39.3 ± 1.9 MPa and E = 540.5 ± 83.7 MPa, p < 0.0001). Aligned PCL/CHT/CNC nanocomposite fibrous scaffolds meet not only the mechanical requirements for tendon TE applications but also provide tendon mimetic extracellular matrix (ECM) topographic cues, a key feature for maintaining tendon cell's morphology and behavior. The strategy proposed here may be extended to other anisotropic aligned nanofibrous scaffolds based on natural/synthetic polymer blends and enable the full exploitation of the advantages provided by their tendon mimetic fibrous structures in tendon TE. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-monitoring fiber reinforced polymer strengthening system for civil engineering infrastructures

NASA Astrophysics Data System (ADS)

Jiang, Guoliang; Dawood, Mina; Peters, Kara; Rizkalla, Sami

2008-03-01

Fiber reinforced polymer (FRP) materials are currently used for strengthening civil engineering infrastructures. The strengthening system is dependant on the bond characteristics of the FRP to the external surface of the structure to be effective in resisting the applied loads. This paper presents an innovative self-monitoring FRP strengthening system. The system consists of two components which can be embedded in FRP materials to monitor the global and local behavior of the strengthened structure respectively. The first component of the system is designed to evaluate the applied load acting on a structure based on elongation of the FRP layer along the entire span of the structure. Success of the global system has been demonstrated using a full-scale prestressed concrete bridge girder which was loaded up to failure. The test results indicate that this type of sensor can be used to accurately determine the load prior to failure within 15 percent of the measured value. The second sensor component consists of fiber Bragg grating sensors. The sensors were used to monitor the behavior of steel double-lap shear splices tested under tensile loading up to failure. The measurements were used to identify abnormal structural behavior such as epoxy cracking and FRP debonding. Test results were also compared to numerical values obtained from a three dimensional shear-lag model which was developed to predict the sensor response.

FRP : Strengthened RC Structures

NASA Astrophysics Data System (ADS)

Teng, J. G.; Chen, J. F.; Smith, S. T.; Lam, L.

2002-01-01

The strengthening of reinforced concrete (RC) structures using advanced fibre-reinforced polymer (FRP) composites, and in particular the behaviour of FRP-strengthened RC structures is a topic which has become very popular in recent years. This popularity has arisen due to the need to maintain and upgrade essential infrastructure in all parts of the world, combined with the well-known advantages of FRP composites, such as good corrosion resistance and ease for site handling due to their light weight. The continuous reduction in the material cost of FRP composites has also contributed to their popularity. While a great amount of research now exists in the published literature on this topic, it is scattered in various journals and conference proceedings. This book therefore provides the first ever comprehensive, state-of-the-art summary of the existing research on FRP strengthening of RC structures, with the emphasis being on structural behaviour and strength models. The main topics covered include: Bond behaviour Flexural and shear strengthening of beams Column strengthening Flexural strengthening of slabs. For each area, the methods of strengthening are discussed, followed by a description of behaviour and failure modes and then the presentation of rational design recommendations, for direct use in practical design of FRP strengthening measures. Researchers, practicing engineers, code writers and postgraduate students in structural engineering and construction materials, as well as consulting firms, government departments, professional bodies, contracting firms and FRP material suppliers will find this an invaluable resource.

Effect of addition of plants-derived polyamide 11 elastomer on the mechanical and tribological properties of hemp fiber reinforced polyamide 1010 composites

NASA Astrophysics Data System (ADS)

Mukaida, Jun; Nishitani, Yosuke; Kitano, Takeshi

2015-05-01

For the purpose of developing the new engineering materials such as structural materials and tribomaterials based on all plants-derived materials, the effect of the addition of plant-derived polyamide 11 Elastomer (PA11E) on the mechanical and tribological properties of hemp fiber(HF) reinforced polyamide 1010 (HF/PA1010) composites was investigated. PA1010 and PA11E (except the polyether groups used as soft segment) were made from plant-derived castor oil. Hemp fiber was surface-treated by two types of treatment: alkali treatment by NaOH solution and surface treatment by ureido silane coupling agent. HF/PA1010/PA11E ternary composites were extruded by a twin screw extruder and injection-molded. Their mechanical properties such as tensile, bending, Izod impact and tribological properties by ring-on-plate type sliding wear testing were evaluated. The effect of the addition of PA11E on the mechanical and tribological properties of HF/PA1010 composite differed for each property. Izod impact strength and specific wear rate improved with the addition of PA11E although tensile strength, modulus, and friction coefficient decreased with PA11E. It follows from these results that it may be possible to develop the new engineering materials with sufficient balance between mechanical and tribological properties.

On the properties evolution of engineered surfaces of thin reinforced thermoplastic tapes during consolidation

NASA Astrophysics Data System (ADS)

Leon, Angel; Perez, Marta; Barasinski, Anais; Abisset-Chavanne, Emmanuelle; Chinesta, Francisco

2017-12-01

Advanced thermoplastic composite materials look to add functional properties to the mechanical ones, the latter usually ensured by the continuous fibers involved in the composite preforms. For that purpose the use of reinforced thermoplastic resins are being considered. These resins usually integrate manometric particles, with a variety of shapes (rods, spheres, discs, ...) with enhanced functional properties, ensuring for example the increase of thermal or electrical conductivities. However, even when considering adequate particles distribution and orientation in the preforms, forming processes induced properties cannot be ignored and they are particuarly critical at the ply interfaces level, where the degree of intimate contact must be maximized while ensuring equivalent functional properties to the ones existing in the bulk. One possibility for maximizing the intimate contact and at the same time controlling the induced functional anisotropy consists of designing engineered surfaces consolidated by the combined action of temperature and pressure. The combined effect results in a microscopic flow that induces at its turn the evolution of the position and orientation of the particles, and consequently the evolution of the associated properties, e.g. thermal and electrical conductivities. In the present work we address a simplified modeling framework of the functional properties evolution during the consolidation of unidirectional tapes. It combines the squeeze flow modeling, the flow induced microstructural anisotropy and its impact on the thermal and electrical conductivities.

Effect of stacking sequence on the coefficients of mutual influence of composite laminates

NASA Astrophysics Data System (ADS)

Dupir (Hudișteanu, I.; Țăranu, N.; Axinte, A.

2016-11-01

Fiber reinforced polymeric (FRP) composites are nowadays widely used in engineering applications due to their outstanding features, such as high specific strength and specific stiffness as well as good corrosion resistance. A major advantage of fibrous polymeric composites is that their anisotropy can be controlled through suitable choice of the influencing parameters. The unidirectional fiber reinforced composites provide much higher longitudinal mechanical properties compared to the transverse ones. Therefore, composite laminates are formed by stacking two or more laminas, with different fiber orientations, as to respond to complex states of stresses. These laminates experience the effect of axial-shear coupling, which is caused by applying normal or shear stresses, implying shear or normal strains, respectively. The normal-shear coupling is expressed by the coefficients of mutual influence. They are engineering constants of primary interest for composite laminates, since the mismatch of the material properties between adjacent layers can produce interlaminar stresses and/or plies delamination. The paper presents the variation of the in-plane and flexural coefficients of mutual influence for three types of multi-layered composites, with different stacking sequences. The results are obtained using the Classical Lamination Theory (CLT) and are illustrated graphically in terms of fiber orientations, for asymmetric, antisymmetric and symmetric laminates. Conclusions are formulated on the variation of these coefficients, caused by the stacking sequence.

Adhesion and Interphase Properties of Reinforced Polymeric Composites

NASA Astrophysics Data System (ADS)

Caldwell, Kyle Bernd

Reinforced polymeric composites are an increasingly utilized material with a wide range of applications. Fiber reinforced polymeric composites, in particular, possess impressive mechanical properties at a fraction of the weight of many other building materials. There will always, however, be a demand for producing lighter, stiffer, and stronger materials. Understanding the mechanism of adhesion and ways to engineer the reinforcement-matrix interphase can lead to the development of new materials with improved mechanical properties, and even impart additional functionality such as electrical conductivity. The performance of reinforced polymeric composites is critically dependent upon the adhesion between the reinforcement and the surrounding polymer. The relative adhesion between a filler and a thermoplastic matrix can be predicted using calculable thermodynamic quantities such as the Gibbs free energy of mixing. A recent model, COSMO-SAC, is capable of predicting the adhesion between organo-silane treated glass surfaces and several thermoplastic materials. COSMO-SAC uses information based on the charge distribution of a molecule's surface to calculate many thermodynamic properties. Density functional theory calculations, which are relative inexpensive computations, generate the information necessary to perform the COSMO-SAC analysis and can be performed on any given molecule. The flexibility of the COSMO-SAC model is one of the main advantages it possesses over other methods for calculating thermodynamic quantities. In many cases the adhesion between a reinforcing fiber and the surrounding matrix may be improved by incorporating interphase modifiers in the vicinity of the fiber surface. The modifiers can improve the fracture toughness and modulus of the interphase, which may improve the stress transfer from the matrix to the fiber. In addition, the interphase modifiers may improve the mechanical interlock between the fiber surface and the bulk polymer, leading to improved adhesion. In recent years, the use of so called "migrating agents" have been used to self-assemble nanoparticle reinforced fiber-matrix interphases in thermosetting resin systems. The inclusion of a modest amount of thermoplastic migrating agent can lead to the formation of a self-assembled interphase, without causing aggregation of nanoparticles in the bulk phase. Formulations containing excess migrating agent, however, can induce aggregation in the bulk of increasing severity with increasing migrating agent concentration. Several techniques were used to study the mechanism by which the migrating agents operate including, scanning electron microscopy, and in situ fluorescence microscopy. The self-assembly mechanism by which migrating agents operate is described well by depletion forces, which are depend on the geometry of the approaching objects, as well as the migrating agent molecular weight and concentration.

A Regeneratively Cooled Thrust Chamber For The Fastrac Engine

NASA Technical Reports Server (NTRS)

Brown, Kendall K.; Sparks, Dave; Woodcock, Gordon

2000-01-01

Abstract This paper presents the development of a low-cost, regeneratively-cooled thrust chamber for the Fastrac engine. The chamber was fabricated using hydraformed copper tubing to form the coolant jacket and wrapped with a fiber reinforced polymer composite Material to form a structural jacket. The thrust chamber design and fabrication approach was based upon Space America. Inc.'s 12,000 lb regeneratively-cooled LOX/kerosene rocket engine. Fabrication of regeneratively cooled thrust chambers by tubewall construction dates back to the early US ballistic missile programs. The most significant innovations in this design was the development of a low-cost process for fabrication from copper tubing (nickel alloy was the usual practice) and use of graphite composite overwrap as the pressure containment, which yields an easily fabricated, lightweight pressure jacket around the copper tubes A regeneratively-cooled reusable thrust chamber can benefit the Fastrac engine program by allowing more efficient (cost and scheduler testing). A proof-of-concept test article has been fabricated and will he tested at Marshall Space Flight Center in the late Summer or Fall of 2000.

Ultrasound elastography to determine the layered mechanical properties of articular cartilage and the importance of such structural characteristics under load.

PubMed

McCredie, Alexandra J; Stride, Eleanor; Saffari, Nader

2009-01-01

Articular cartilage is an important load bearing surface in joints. Prone to damage and with limited self-repair ability, it is of interest to tissue engineers. Tissue implant design requires full mechanical characterisation of healthy native tissue. A layered organisation of reinforcing collagen fibrils exists in healthy articular cartilage and is believed to be important for correct tissue function. However, the effect of this on the local depth-dependent elasticity is poorly characterised. In this study, quasi-static ultrasound elastography is used both to compare the depth-dependent elastic properties of cartilage structures with two different fibril arrangements and to monitor changes in the elastic properties of engineered samples during development. Results show global and local elastic properties of the native tissues and highlight the differences caused by fibril architecture. At increasing culture periods, results from the engineered tissue demonstrate an increase in elastic stiffness and the time taken to reach equilibrium under a quasi-static displacement. The study suggests suitability of ultrasound elastography for design and monitoring engineered articular cartilage.

High-Temperature, Lightweight, Self-Healing Ceramic Composites for Aircraft Engine Applications

NASA Technical Reports Server (NTRS)

Raj, Sai V.; Bhatt, Ramkrishna

2013-01-01

The use of reliable, high-temperature, lightweight materials in the manufacture of aircraft engines is expected to result in lower fossil and biofuel consumption, thereby leading to cost savings and lower carbon emissions due to air travel. Although nickel-based superalloy blades and vanes have been successfully used in aircraft engines for several decades, there has been an increased effort to develop high-temperature, lightweight, creep-resistant substitute materials under various NASA programs over the last two decades. As a result, there has been a great deal of interest in developing SiC/SiC ceramic matrix composites (CMCs) due to their higher damage tolerance compared to monolithic ceramics. Current-generation SiC/SiC ceramic matrix composites rely almost entirely on the SiC fibers to carry the load, owing to the premature cracking of the matrix during loading. Thus, the high-temperature usefulness of these CMCs falls well below their theoretical capabilities. The objective of this work is to develop a new class of high-temperature, lightweight, self-healing, SiC fiber-reinforced, engineered matrix ceramic composites.

Investigation of the fuel feed line failures on the Space Shuttle main engine

NASA Technical Reports Server (NTRS)

Larson, E. W.

1980-01-01

The Space Shuttle Main Engine (SSME) development program experienced two similar appearing fuel feed line failures during the shutdown portion of two engine tests. Failure investigations into each incident showed that a few cycles of high-amplitude transient strain occurring during the start and cutoff portions of each test could have either accumulated damage and led to a fatigue failure after 46 tests, or caused rupture in a low-strength weld joint. The cause of the high strain was traced to a period of unsteady flow separation during the start and cutoff of each test coincident with the oblique shock approaching the nozzle exit. Since elimination of the flow separation was impractical, the steps taken to allow engine development and flight preparations to continue were: (1) establish the safe operating life of the nozzle, (2) reinforce all low-strength welds, and (3) eliminate the use of thin-wall fuel feed lines. In parallel, the feed line was redesigned and fabrication was initiated on units to be incorporated into the development program.

Behaviour of human mesenchymal stem cells on a polyelectrolyte-modified HEMA hydrogel for silk-based ligament tissue engineering.

PubMed

Bosetti, M; Boccafoschi, F; Calarco, A; Leigheb, M; Gatti, S; Piffanelli, V; Peluso, G; Cannas, M

2008-01-01

The aim of this study was to design a functional bio-engineered material to be used as scaffold for autologous mesenchymal stem cells in ligament tissue engineering. Polyelectrolyte modified HEMA hydrogel (HEMA-co-METAC), applied as coating on silk fibroin fibres, has been formulated in order to take advantage of the biocompatibility of the polyelectrolyte by increasing its mechanical properties with silk fibres. Human bone marrow mesenchymal stem cells behaviour on such reinforced polyelectrolyte has been studied by evaluating cell morphology, cell number, attachment, spreading and proliferation together with collagen matrix production and its mRNA expression. Silk fibroin fibres matrices with HEMA-co-METAC coating exhibited acceptable mechanical behaviour compared to the natural ligament, good human mesenchymal stem cell adhesion and with mRNA expression studies higher levels of collagen types I and III expression when compared to control cells on polystyrene. These data indicate high expression of mRNA for proteins responsible for the functional characteristics of the ligaments and suggest a potential for use of this biomaterial in ligament tissue-engineering applications.

Numerical Simulation of Thermal Performance of Glass-Fibre-Reinforced Polymer

NASA Astrophysics Data System (ADS)

Zhao, Yuchao; Jiang, Xu; Zhang, Qilin; Wang, Qi

2017-10-01

Glass-Fibre-Reinforced Polymer (GFRP), as a developing construction material, has a rapidly increasing application in civil engineering especially bridge engineering area these years, mainly used as decorating materials and reinforcing bars for now. Compared with traditional construction material, these kinds of composite material have obvious advantages such as high strength, low density, resistance to corrosion and ease of processing. There are different processing methods to form members, such as pultrusion and resin transfer moulding (RTM) methods, which process into desired shape directly through raw material; meanwhile, GFRP, as a polymer composite, possesses several particular physical and mechanical properties, and the thermal property is one of them. The matrix material, polymer, performs special after heated and endue these composite material a potential hot processing property, but also a poor fire resistance. This paper focuses on thermal performance of GFRP as panels and corresponding researches are conducted. First, dynamic thermomechanical analysis (DMA) experiment is conducted to obtain the glass transition temperature (Tg) of the object GFRP, and the curve of bending elastic modulus with temperature is calculated according to the experimental data. Then compute and estimate the values of other various thermal parameters through DMA experiment and other literatures, and conduct numerical simulation under two condition respectively: (1) the heat transfer process of GFRP panel in which the panel would be heated directly on the surface above Tg, and the hot processing under this temperature field; (2) physical and mechanical performance of GFRP panel under fire condition. Condition (1) is mainly used to guide the development of high temperature processing equipment, and condition (2) indicates that GFRP’s performance under fire is unsatisfactory, measures must be taken when being adopted. Since composite materials’ properties differ from each other and their high temperature parameters can’t be obtained through common methods, some parameters are estimated, the simulation is to guide the actual high temperature experiment, and the parameters will also be adjusted by then.

Damage Tolerance Enhancement of Carbon Fiber Reinforced Polymer Composites by Nanoreinforcement of Matrix

NASA Astrophysics Data System (ADS)

Fenner, Joel Stewart

Nanocomposites are a relatively new class of materials which incorporate exotic, engineered nanoparticles to achieve superior material properties. Because of their extremely small size and well-ordered structure, many nanoparticles possess properties that exceed those offered by a wide range of other known materials, making them attractive candidates for novel materials engineering development. Their small size is also an impediment to their practical use, as they typically cannot be employed by themselves to realize those properties in large structures. Furthermore, nanoparticles typically possess strong self-affinity, rendering them difficult to disperse uniformly into a composite. However, contemporary research has shown that, if well-dispersed, nanoparticles have great capacity to improve the mechanical properties of composites, especially damage tolerance, in the form of fracture toughness, fatigue life, and impact damage mitigation. This research focuses on the development, manufacturing, and testing of hybrid micro/nanocomposites comprised of woven carbon fibers with a carbon nanotube reinforced epoxy matrix. Material processing consisted of dispersant-and-sonication based methods to disperse nanotubes into the matrix, and a vacuum-assisted wet lay-up process to prepare the hybrid composite laminates. Various damage tolerance properties of the hybrid composite were examined, including static strength, fracture toughness, fatigue life, fatigue crack growth rate, and impact damage behavior, and compared with similarly-processed reference material produced without nanoreinforcement. Significant improvements were obtained in interlaminar shear strength (15%), Mode-I fracture toughness (180%), shear fatigue life (order of magnitude), Mode-I fatigue crack growth rate (factor of 2), and effective impact damage toughness (40%). Observations by optical microscopy, scanning electron microscopy, and ultrasonic imaging showed significant differences in failure behavior and fracture morphology between the two materials, related to the differences in properties. Altogether these results provided a means for proposing an explanation of the mechanism of reinforcement (and damage tolerance enhancement) provided by carbon nanotubes in hybrid composite materials.

Proposed Methodology for Design of Carbon Fiber Reinforced Polymer Spike Anchors into Reinforced Concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacFarlane, Eric Robert

The included methodology, calculations, and drawings support design of Carbon Fiber Reinforced Polymer (CFRP) spike anchors for securing U-wrap CFRP onto reinforced concrete Tbeams. This content pertains to an installation in one of Los Alamos National Laboratory’s facilities. The anchors are part of a seismic rehabilitation to the subject facility. The information contained here is for information purposes only. The reader is encouraged to verify all equations, details, and methodology prior to usage in future projects. However, development of the content contained here complied with Los Alamos National Laboratory’s NQA-1 quality assurance program for nuclear structures. Furthermore, the formulations andmore » details came from the referenced published literature. This literature represents the current state of the art for FRP anchor design. Construction personnel tested the subject anchor design to the required demand level demonstrated in the calculation. The testing demonstrated the ability of the anchors noted to carry loads in excess of 15 kips in direct tension. The anchors were not tested to failure in part because of the hazards associated with testing large-capacity tensile systems to failure. The calculation, methodology, and drawing originator was Eric MacFarlane of Los Alamos National Laboratory’s (LANL) Office of Seismic Hazards and Risk Mitigation (OSHRM). The checker for all components was Mike Salmon of the LANL OSHRM. The independent reviewers of all components were Insung Kim and Loring Wyllie of Degenkolb Engineers. Note that Insung Kim contributed to the initial formulations in the calculations that pertained directly to his Doctoral research.« less

Investigation on Mechanical and Fatigue behaviour of Aluminium Based SiC/ZrO2 Particle Reinforced MMC

NASA Astrophysics Data System (ADS)

Ramesh, S.; Govindaraju, N.; Suryanarayan, C. P.

2018-04-01

The study is the work on Aluminium Metal Matrix Composites (MMC’s), which have wider applications in automobile, aerospace and defense industries, hi-tech engineering and power transmission due to their lightweight, high strength and other unique properties. The Aluminium Matrix Composites (AMC’s) refer to a kind of light weight high performance Aluminium centric material system. AMC’s consist of a non-metallic reinforcement which when included into aluminium matrix offers an advantage over the base material. Reinforcements like SiC, B4C, Al2O3, TiC, TiB2, TiO2 are normally preferred to improve mechanical properties of such composites. Here Aluminium 6061 is preferred as matrix material, while silicon carbide (SiC) and Zirconium di-oxide (ZrO2) is selected as reinforcement compounds. Conventional Stir casting procedure is employed to fabricate the necessary composites compositions, which are I. Al:SiC::100:5 and II. Al:ZrO2:SiC::100:3:2. Experimental results depict that the composition II provides higher hardness of 53.6 RHN as opposed to 45.8 RHN of composition I. In tensile strength composition II demonstrates 96.43 N/mm2 as opposed to 67.229 N/mm2 tensile strength of composition II. The fatigue test indicate a expected number of life cycles to failure of 105 cycles for composition II and over 104 cycles for composition I, at stress ranges of 79.062 MPa and 150.651 MPa respectively.

Self Healing Fibre-reinforced Polymer Composites: an Overview

NASA Astrophysics Data System (ADS)

Bond, Ian P.; Trask, Richard S.; Williams, Hugo R.; Williams, Gareth J.

Lightweight, high-strength, high-stiffness fibre-reinforced polymer composite materials are leading contenders as component materials to improve the efficiency and sustainability of many forms of transport. For example, their widespread use is critical to the success of advanced engineering applications, such as the Boeing 787 and Airbus A380. Such materials typically comprise complex architectures of fine fibrous reinforcement e.g. carbon or glass, dispersed within a bulk polymer matrix, e.g. epoxy. This can provide exceptionally strong, stiff, and lightweight materials which are inherently anisotropic, as the fibres are usually arranged at a multitude of predetermined angles within discrete stacked 2D layers. The direction orthogonal to the 2D layers is usually without reinforcement to avoid compromising in-plane performance, which results in a vulnerability to damage in the polymer matrix caused by out-of-plane loading, i.e. impact. Their inability to plastically deform leaves only energy absorption via damage creation. This damage often manifests itself internally within the material as intra-ply matrix cracks and inter-ply delaminations, and can thus be difficult to detect visually. Since relatively minor damage can lead to a significant reduction in strength, stiffness and stability, there has been some reticence by designers for their use in safety critical applications, and the adoption of a `no growth' approach (i.e. damage propagation from a defect constitutes failure) is now the mindset of the composites industry. This has led to excessively heavy components, shackling of innovative design, and a need for frequent inspection during service (Richardson 1996; Abrate 1998).

Directionally solidified composite systems under evaluation

NASA Technical Reports Server (NTRS)

Ashbrook, R. L.

1974-01-01

The directionally solidified eutectic in-situ composites being evaluated for use as turbine materials range from ductile-ductile systems, where both matrix and reinforcement are ductile, to brittle-brittle systems, where both phases are brittle. The alloys most likely to be used in gas turbine engines in the near term are the lamellar ductile-semi ductile alloys gamma prime-delta, Ni3Al-Ni3Nb and gamma/gamma prime-delta Ni,Cr,Cb,Al/Ni3Al-Ni3Nb and the fibrous ductile-brittle alloys M-MC CoTaC or NiTaC and M-M7C3(Co,Cr,Al)-(Cr,Co)7C3. The results of tests are given which indicate that gamma prime strengthened NiTaC alloys and a (Co,Cr,Al)7C3 have greater tensile strength than the strongest superalloys at temperatures up to about 600 C. The gamma prime-delta and gamma/gamma prime-delta alloys in the Ni,Al,Nb(Cr) systems have greater tensile strength than the superalloys at temperatures greater than 800 C. At low stresses fibrous carbide reinforced eutectic alloys have longer lives at high temperatures than the strongest superalloys. Lamellar delta, Ni3Nb reinforced eutectic alloys have longer lives at high temperatures than the strongest superalloys at all stresses. The experience currently being gained in designing with the brittle ceramics SiC and Si3N4 may eventually be applied to ceramic matrix eutectic in-situ composites. However, the refractory metal fiber reinforced brittle-ductile systems may find acceptance as turbine materials before the ceramic-ceramic brittle-brittle systems.

Can plant-based natural flax replace mineral-based basalt and synthetic E-glass for fibre reinforced polymer tubular energy absorbers? A comparative study on quasi-static axial crushing

NASA Astrophysics Data System (ADS)

Yan, Libo; Wang, Bo; Kasal, Bohumil

2017-12-01

Using plant-based natural fibres to substitute glass fibres as reinforcement of composite materials is of particular interest due to their economic, technical and environmental significance. One potential application of plant-based natural fibre reinforced polymer (FRP) composites is in automotive engineering as crushable energy absorbers. Current study experimentally investigated and compared the energy absorption efficiency of plant-based natural flax, mineral-based basalt and glass FRP composite tubular energy absorbers subjected to quasi-static axial crushing. The effects of number of flax fabric layer, the use of foam-filler and the type of fibre materials on the crashworthiness characteristics and energy absorption capacities were discussed. In addition, the failure mechanisms of the hollow and foam-filled flax, basalt and glass FRP tubes in quasi-static axial crushing were analysed and compared. The test results showed that the energy absorption capabilities of both hollow and foam-filled energy absorbers made of flax were superior to the corresponding energy absorbers made of basalt and were close to energy absorbers made of glass. This study therefore indicated that flax fibre has the great potential to be suitable replacement of basalt and glass fibres for crushable energy absorber application.

Characterization and Mechanical Properties of 2014 Aluminum Alloy Reinforced with Al2O3p Composite Produced by Two-Stage Stir Casting Route

NASA Astrophysics Data System (ADS)

Bharath, V.; Ajawan, Santhrusht S.; Nagaral, Madev; Auradi, Virupaxi; Kori, Shivaputrappa Amarappa

2018-02-01

Metal matrix composites (MMC's) form appropriate choice of materials where there is a demand for stiffness, strength combined with low weight for different applications. The applications of Aluminum based MMC's as engineering materials has been exceedingly increased in almost all industrial sectors. Aluminum strengthened with Al2O3p gives excellent physical and mechanical properties like high hardness, low density, high electrical conductivity etc., which are generally used in the field of aerospace, automobile and industrial applications. In present work, an attempt is being made to integrate 2014 Al alloy with Al2O3p by two stage stir casting with addition level of reinforcement maintained at 9 and 12 wt%. Microstructural characterization carried out using scanning electron microscopy showed fairly uniform distribution of Al2O3p with grain refinement of the matrix. These prepared composites are mechanically characterized as per the ASTM standards using computerized universal testing machine. Improvements in tensile strength, density and hardness of the prepared composites were observed with increase in the reinforcement wt%. Percentage improvements of 5.09% (9 wt%), 17.65% (12 wt%) in terms of tensile strength and 29.18% (9 wt%), 43.69% (12 wt%) in terms of hardness were obtained respectively.

Flexure and impact properties of glass fiber reinforced nylon 6-polypropylene composites

NASA Astrophysics Data System (ADS)

Kusaseh, N. M.; Nuruzzaman, D. M.; Ismail, N. M.; Hamedon, Z.; Azhari, A.; Iqbal, A. K. M. A.

2018-03-01

In recent years, polymer composites are rapidly developing and replacing the metals or alloys in numerous engineering applications. These polymer composites are the topic of interests in industrial applications such as automotive and aerospace industries. In the present research study, glass fiber (GF) reinforced nylon 6 (PA6)-polypropylene (PP) composite specimens were prepared successfully using injection molding process. Test specimens of five different compositions such as, 70%PA6+30%PP, 65%PA6+30%PP+5%GF, 60%PA6+30%PP+10%GF, 55%PA6+30%PP+15%GF and 50%PA6+30%PP+20%GF were prepared. In the experiments, flexure and impact tests were carried out. The obtained results revealed that flexure and impact properties of the polymer composites were significantly influenced by the glass fiber content. Results showed that flexural strength is low for pure polymer blend and flexural strength of GF reinforced composite increases gradually with the increase in glass fiber content. Test results also revealed that the impact strength of 70%PA6+30%PP is the highest and 55%PA6+30%PP+15%GF composite shows moderate impact strength. On the other hand, 50%PA6+30%PP+20%GF composite shows low toughness or reduced impact strength.

Intra-Laminar Fracture Toughness of Glass Fiber Reinforced Polymer By Using Theory, Experimentation and FEA

NASA Astrophysics Data System (ADS)

Firojkhan, Pathan; Tanpure, Kshitijit; Dawale, Ajinkya; Patil, Shital

2018-04-01

Fiber reinforced polymer (FRP) composites are widely use in aerospace, marine, auto-mobile and civil engineering applications because of their high strength-to-weight and stiffness-to-weight ratios, corrosion resistance and potentially high durability. The purpose of this research is to experimentally investigate the mechanical and fracture properties of glass-fiber reinforced polyester composite material, 450 g/m 2 randomly distributed glass-fiber mat also known as woven strand mat with polyester resin as a matrix. The samples have been produced by the conventional hand layup process and the specimens were prepared as per the ASTM standards. The tensile test was performed on the composite specimens using Universal testing machine (UTM) which are used for the finite element simulation of composite Layered fracture model. The mechanical properties were evaluated from the stress vs. strain curve obtained from the test result. Later, fracture tests were performed on the CT specimen. In case of CT specimen the load vs. Displacement plot obtained from the experimental results was used to determine the fracture properties of the composite. The failure load of CT specimen using FEA is simulated which gives the Stress intensity factor by using FEA. Good agreement between the FEA and experimental results was observed.

Feasibility of Electrochemical Deposition of Nickel/Silicon Carbide Fibers Composites over Nickel Superalloys

NASA Astrophysics Data System (ADS)

Ambrosio, E. P.; Abdul Karim, M. R.; Pavese, M.; Biamino, S.; Badini, C.; Fino, P.

2017-05-01

Nickel superalloys are typical materials used for the hot parts of engines in aircraft and space vehicles. They are very important in this field as they offer high-temperature mechanical strength together with a good resistance to oxidation and corrosion. Due to high-temperature buckling phenomena, reinforcement of the nickel superalloy might be needed to increase stiffness. For this reason, it was thought to investigate the possibility of producing composite materials that might improve properties of the metal at high temperature. The composite material was produced by using electrochemical deposition method in which a composite with nickel matrix and long silicon carbide fibers was deposited over the nickel superalloy. The substrate was Inconel 718, and monofilament continuous silicon carbide fibers were chosen as reinforcement. Chemical compatibility was studied between Inconel 718 and the reinforcing fibers, with fibers both in an uncoated condition, and coated with carbon or carbon/titanium diboride. Both theoretical calculations and experiments were conducted, which suggested the use of a carbon coating over the fibers and a buffer layer of nickel to avoid unwanted reactions between the substrate and silicon carbide. Deposition was then performed, and this demonstrated the practical feasibility of the process. Yield strength was measured to detect the onset of interface debonding between the substrate and the composite layer.

The behaviour of reinforced concrete structure due to earthquake load using Time History analysis Method

NASA Astrophysics Data System (ADS)

Afifuddin, M.; Panjaitan, M. A. R.; Ayuna, D.

2017-02-01

Earthquakes are one of the most dangerous, destructive and unpredictable natural hazards, which can leave everything up to a few hundred kilometres in complete destruction in seconds. Indonesia has a unique position as an earthquake prone country. It is the place of the interaction for three tectonic plates, namely the Indo-Australian, Eurasian and Pacific plates. Banda Aceh is one of the cities that located in earthquake-prone areas. Due to the vulnerable conditions of Banda Aceh some efforts have been exerted to reduce these unfavourable conditions. Many aspects have been addressed, starting from community awareness up to engineering solutions. One of them is all buildings that build in the city should be designed as an earthquake resistant building. The objectives of this research are to observe the response of a reinforced concrete structure due to several types of earthquake load, and to see the performance of the structure after earthquake loads applied. After Tsunami in 2004 many building has been build, one of them is a hotel building located at simpang lima. The hotel is made of reinforced concrete with a height of 34.95 meters with a total area of 8872.5 m2 building. So far this building was the tallest building in Banda Aceh.

Mechanical Properties in a Bamboo Fiber/PBS Biodegradable Composite

NASA Astrophysics Data System (ADS)

Ogihara, Shinji; Okada, Akihisa; Kobayashi, Satoshi

In recent years, biodegradable plastics which have low effect on environment have been developed. However, many of them have lower mechanical properties than conventional engineering plastics. Reinforcing them with a natural fiber is one of reinforcing methods without a loss of their biodegradability. In the present study, we use a bamboo fiber as the reinforcement and polybutylenesuccinate (PBS) as the matrix. We fabricate long fiber unidirectional composites and cross-ply laminate with different fiber weight fractions (10, 20, 30, 40 and 50wt%). We conduct tensile tests to evaluate the mechanical properties of these composites. In addition, we measure bamboo fiber strength distribution. We discuss the experimentally-obtained properties based on the mechanical properties of the constituent materials. Young's modulus and tensile strength in unidirectional composite and cross-ply laminate increase with increasing fiber weight fraction. However, the strain at fracture showed decreasing tendency. Young's modulus in fiber and fiber transverse directions are predictable by the rules of mixture. Tensile strength in fiber direction is lower than Curtin's prediction of strength which considers distribution of fiber strength. Young's modulus in cross-ply laminate is predictable by the laminate theory. However, analytical prediction of Poisson's ratio in cross-ply laminate by the laminate theory is lower than the experimental results.

Influence of reinforcement mesh configuration for improvement of concrete durability

NASA Astrophysics Data System (ADS)

Pan, Chong-gen; Jin, Wei-liang; Mao, Jiang-hong; Zhang, Hua; Sun, Li-hao; Wei, Dong

2017-10-01

Steel bar in concrete structures under harsh environmental conditions, such as chlorine corrosion, seriously affects its service life. Bidirectional electromigration rehabilitation (BIEM) is a new method of repair technology for reinforced concrete structures in such chloride corrosion environments. By applying the BIEM, chloride ions can be removed from the concrete and the migrating corrosion inhibit can be moved to the steel surface. In conventional engineering, the concrete structure is often configured with a multi-layer steel mesh. However, the effect of the BIEM in such structures has not yet been investigated. In this paper, the relevant simulation test is carried out to study the migration law of chloride ions and the migrating corrosion inhibitor in a concrete specimen with complex steel mesh under different energizing modes. The results show that the efficiency of the BIEM increases 50% in both the monolayer steel mesh and the double-layer steel mesh. By using the single-sided BIEM, 87% of the chloride ions are removed from the steel surface. The different step modes can affect the chloride ion removal. The chloride ions within the range of the reinforcement protective cover are easier to be removed than those in the concrete between the two layers of steel mesh. However, the amount of migrating corrosion inhibitor is larger in the latter circumstances.

ONR Tokyo Scientific Bulletin. Volume 6, Number 1, January-March 1981,

DTIC Science & Technology

1981-03-01

festival. The boats, most of which are rather new, are made of fiber glass, powered by high horsepower outboard engines, and hauled up onto the beach by...etc. The tradition of gaseous electronics in Australia was reinforced by L. G. H. Huxley, who is primarily a theoretical physicist, first at the...quality. The Institute of Ceramics is also trying to develop low-loss optical fibers . Theoretical values of 2-3db/kMi at ,=O.S5%m have been determined

Training Objectives for Tank Platoon Leaders Covering Tasks Performed during Four Armor Operations

DTIC Science & Technology

1983-01-01

screens to conceal their movement to covered and concealed positions. The M250 grenade launcher consists of two six-barreled dischargers wired for two...generates smoke by the injestion of fuel onto the hot engine exhaust system. The smoke screen generated by VEESS is used to compli- ment the M250 smoke...grenade system by reinforcing and sustaining the screen created by the M250 system. The purpose of the smoke producing systems is to make it more

Recent developments in chaotic dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ott, E.

1994-02-01

Before the relatively recent wide acceptance of the existence of chaotic dynamics, many physicists and engineers were under the impression that simple systems could necessarily only display simple solutions. This feeling had been unintentionally reinforced by conventional college courses which emphasize linear dynamics (partly because that is the only case with nice general solutions). More recently, physical experiments and numerical examples have abundantly demonstrated how wrong this feeling is. A brief review of chaotic dynamics is presented. Topics discussed include basic concepts, recent developments, and applications.

SINGER: A Computer Code for General Analysis of Two-Dimensional Reinforced Concrete Structures. Volume 1. Solution Process

DTIC Science & Technology

1975-05-01

Conference on Earthquake Engineering, Santiago de Chile, 13-18 January 1969, Vol. I , Session B2, Chilean Association oil Seismology and Earth- quake...Nuclear Agency May 1975 DISTRIBUTED BY: KJ National Technical Information Service U. S. DEPARTMENT OF COMMERCE ^804J AFWL-TR-74-228, Vol. I ...CM o / i ’•fu.r ) V V AFWL-TR- 74-228 Vol. I SINGER: A COMPUTER CODE FOR GENERAL ANALYSIS OF TWO-DIMENSIONAL CONCRETE STRUCTURES Volum« I

Economically effective material forms for composites

NASA Astrophysics Data System (ADS)

Woolstencroft, Dave

This paper will consider advanced composites and the new degrees of freedom that are available to the composites engineer to be able to make parts that combine both an economic performance superior to existing systems, with no additional production investment, and high mechanical property translations. This unique advantage comes about through some pioneering and innovative work in the different forms of material into which the reinforcing fibers can be configured. The presentation will highlight the unique advantages and show a pioneering aerostructural application of this material form.

Developing Capacity or a Culture of Dependency: Are Humanitarian Assistance Projects Initiated by the Provincial Reconstruction Teams Reinforcing Dependency or True Capacity in the Paktia-Khost Provinces of Afghanistan?

DTIC Science & Technology

2013-05-22

47 Prebisch found that developing countries were mainly primary producers, whereas developed countries were industrial producers. Primary producers...can do nothing to add value to the corn, potatoes, copper, lumber etc. that they produce, whereas industrial countries can add value (and increase...the price) of cars, planes, machines, engines, etc. So industrial countries grow faster than primary producers, and in essence, exploit them

U.S. Army Research Office Workshop on Smart Materials, Structures and Mathematical Issues Held in Blacksburg, Virginia on 15-16 September 1988

DTIC Science & Technology

1989-01-01

prestrained Nitinol (an alloy of nickel and titanium) wires are embedded in an off-axis position in the graphite fiber reinforced epoxy composite beam... Nitinol ) alloy. Shape memory alloys have been applied to a number of items including connectors and heat engines, but have usually found application in... nitinol wire; the design includes prevention from ancillary jams. Miwa (1985) discusses the use of SMA actuator to sequential robotic control of multiple

Investing in Software Sustainment

DTIC Science & Technology

2015-04-30

colored arrows simply represent a reinforcing  loop called the “ Bandwagon   Effect ”.  This  effect   simply means that a series of successful missions will...the Software Engineering Institute (SEI) developed a simulation model for analyzing the effects of changes in demand for software sustainment and the...developed a simulation model for analyzing the effects of changes in demand for software sustainment and the corresponding funding decisions. The model

Critical Behavior of Transport and Mechanical Properties in Particulate Dispersions and Granular Media

DTIC Science & Technology

1988-07-29

ORGANIZATION 6b. OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION University of Southern 1 (i aplicable ) It California I J R 6c. ADDRESS (City, State...Materials Based on the Theory of "Compound Mobilized Planes" (CMP) and "Spatial Mobilized Planes" (SMP), in Vol. II of Advances in the Mechanics and the Flow...of Disordered and Reinforced Materials", M. S. Thesis , M. D. Stephens, Department of Chemical Engineering, May 1988, , 13 UNIVERSITY OF SOUTHERN

Additive Layer Manufacturing of Biologically Inspired Short Fibre Reinforced Composites

DTIC Science & Technology

2014-03-01

combination.   It   is   frequently   the   determining   factor   for   the   type   of   fracture   mechanism  observed   [9...Thin Solid Films, 1998. 334(1–2): p. 60-64. 56. Cannas, A., Fracture Mechanics and Failure Analysis of Hollow Shaped Fibre GFRP Composites, in ACCIS...architectures inspired by nature for improving the mechanical and functional properties of engineered materials. The study was advanced on two fronts: (1

Potential Applications of Alkali-Activated Alumino-Silicate Binders in Military Operations

DTIC Science & Technology

1985-11-01

Geopolymers for Reinforced Plastics/ Composits ," PACTEC 󈨓, Society of Plastic Engineers, Costa Mesa, CA, 1979, pp. 151-153. Davidovits, Joseph. 1983...34 Geopolymers II, Processing and Applications of Ultra-High Temperature, Inorganic Matrix Resin for Cast Composite Structures, Molds and Tools for RP/C and...alumino-silicate hydrates with an approximate composition of 3CaO - AI20 3 • 2i0 2 2120, begin to crystallize. As the gels begin to coalesce, bound water

Nanotechnology Concepts at MSFC: Engineering Directorate

NASA Technical Reports Server (NTRS)

Bhat, Biliyar; Kaul, Raj; Shah, Sandeep; Smithers, Gweneth; Watson, Michael D.

2000-01-01

Nanotechnology is the art and science of building materials and devices at the ultimate level of finesse: atom by atom. Our nation's space program has needs for miniaturization of components, minimization of weight and maximization of performance, and nanotechnology will help us get there. MSFC - Engineering Directorate (ED) is committed to developing nanotechnology that will enable MSFC missions in space transportation, space science and space optics manufacturing. MSFC-ED has a dedicated group of technologists who are currently developing high pay-off nanotechnology concepts. This poster presentation will outline some of the concepts being developed at this time including, nanophase structural materials, carbon nanotube reinforced metal and polymer matrix composites, nanotube temperature sensors and aerogels. The poster will outline these concepts and discuss associated technical challenges in turning these concepts into real components and systems.

Nanotechnology Concepts at Marshall Space Flight Center: Engineering Directorate

NASA Technical Reports Server (NTRS)

Bhat, B.; Kaul, R.; Shah, S.; Smithers, G.; Watson, M. D.

2001-01-01

Nanotechnology is the art and science of building materials and devices at the ultimate level of finesse: atom by atom. Our nation's space program has need for miniaturization of components, minimization of weight, and maximization of performance, and nanotechnology will help us get there. Marshall Space Flight Center's (MSFC's) Engineering Directorate is committed to developing nanotechnology that will enable MSFC missions in space transportation, space science, and space optics manufacturing. MSFC has a dedicated group of technologists who are currently developing high-payoff nanotechnology concepts. This poster presentation will outline some of the concepts being developed including, nanophase structural materials, carbon nanotube reinforced metal and polymer matrix composites, nanotube temperature sensors, and aerogels. The poster will outline these concepts and discuss associated technical challenges in turning these concepts into real components and systems.

Advanced Physics Labs and Undergraduate Research: Helping Them Work Together

NASA Astrophysics Data System (ADS)

Peterson, Richard W.

2009-10-01

The 2009 Advanced Lab Topical Conference in Ann Arbor affirmed the importance of advanced labs that teach crucial skills and methodologies by carefully conducting a time-honored experiment. Others however argued that such a constrained experiment can play a complementary role to more open-ended, project experiences. A genuine ``experiment'' where neither student or faculty member is exactly sure of the best approach or anticipated result can often trigger real excitement, creativity, and career direction for students while reinforcing the advanced lab and undergraduate research interface. Several examples are cited in areas of AMO physics, optics, fluids, and acoustics. Colleges and universities that have dual-degree engineering, engineering physics, or applied physics programs may especially profit from interdisciplinary projects that utilize optical, electromagnetic, and acoustical measurements in conjunction with computational physics and simulation.

Composite materials. Volume 3 - Engineering applications of composites. Volume 4 - Metallic matrix composites. Volume 8 - Structural design and analysis, Part 2

NASA Technical Reports Server (NTRS)

Noton, B. R. (Editor); Kreider, K. G.; Chamis, C. C.

1974-01-01

This volume discusses a vaety of applications of both low- and high-cost composite materials in a number of selected engineering fields. The text stresses the use of fiber-reinforced composites, along with interesting material systems used in the electrical and nuclear industries. As to technology transfer, a similarity is noted between many of the reasons responsible for the utilization of composites and those problems requiring urgent solution, such as mechanized fabrication processes and design for production. Features topics include road transportation, rail transportation, civil aircraft, space vehicles, builing industry, chemical plants, and appliances and equipment. The laminate orientation code devised by Air Force materials laboratory is included. Individual items are announced in this issue.

An Investigation of Factors Affecting How Engineers and Scientists Seek Information

NASA Technical Reports Server (NTRS)

Anderson, Claire J; Glassman, Myron; McAfee, R. Bruce; Pinelli, Thomas

2001-01-01

This study investigated how 872 US aerospace scientists and engineers select information carriers. When considering oral and written information carriers, the principle of least effort was supported with a strong preference for oral communication over written communication. In examining how the respondents select written carriers, the decision to use or not to use a written carrier was found to be primarily a function of the perceived importance of the carrier's information to a person's work. Task uncertainty and task complexity were found to be significant, but not the primary nor a totally consistent criteria. The perceived quality and accessibility of written carriers were not found significant. The findings reinforce the need for firms to hire knowledgeable employees, to provide them with comprehensive training programs, and to develop formal and informal communication networks.

Rapid and Tunable Control of Protein Stability in Caenorhabditis elegans Using a Small Molecule

PubMed Central

Cho, Ukrae; Zimmerman, Stephanie M.; Chen, Ling-chun; Owen, Elliot; Kim, Jesse V.; Kim, Stuart K.; Wandless, Thomas J.

2013-01-01

Destabilizing domains are conditionally unstable protein domains that can be fused to a protein of interest resulting in degradation of the fusion protein in the absence of stabilizing ligand. These engineered protein domains enable rapid, reversible and dose-dependent control of protein expression levels in cultured cells and in vivo. To broaden the scope of this technology, we have engineered new destabilizing domains that perform well at temperatures of 20–25°C. This raises the possibility that our technology could be adapted for use at any temperature. We further show that these new destabilizing domains can be used to regulate protein concentrations in C. elegans. These data reinforce that DD can function in virtually any organism and temperature. PMID:23991108

Ceramic fibers for matrix composites in high-temperature engine applications

PubMed

Baldus; Jansen; Sporn

1999-07-30

High-temperature engine applications have been limited by the performance of metal alloys and carbide fiber composites at elevated temperatures. Random inorganic networks composed of silicon, boron, nitrogen, and carbon represent a novel class of ceramics with outstanding durability at elevated temperatures. SiBN(3)C was synthesized by pyrolysis of a preceramic N-methylpolyborosilazane made from the single-source precursor Cl(3)Si-NH-BCl(2). The polymer can be processed to a green fiber by melt-spinning, which then undergoes an intermediate curing step and successive pyrolysis. The ceramic fibers, which are presently produced on a semitechnical scale, combine several desired properties relevant for an application in fiber-reinforced ceramic composites: thermal stability, mechanical strength, high-temperature creep resistivity, low density, and stability against oxidation or molten silicon.