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2012 SAMPE International Symposium and Exhibition - Emerging Opportunities: Materials and Process Solutions

作者： Hao, Ayou Zhao, Haifeng Jiang, Wei Chen, Jonathan Texas Materials Institute Materials Science and Engineering Program University of Texas at Austin Austin TX 78712 United States School of Human Ecology University of Texas at Austin Austin TX 78712 United States Department of Aerospace Engineering and Engineering Mechanics University of Texas at Austin Austin TX 78712 United States

ISBN: (纸本)9781934551127

With an industrial trend of going green, the use of natural fibers in polymer composites is growing rapidly, especially in the automotive industry. The objectives of this research are to investigate the processability of kenaf fibers in making nonwoven composites for automotive interior parts and to explore the composite end-use performance in terms of physical structure, mechanical properties, thermal stability, and acoustical behavior. The kenaf/polypropylene(KF/PP) composites were fabricated with 50/50 blend ratio by weight. All nonwovens were produced by carding and needle-punching techniques and thermally bonded by a panel press. The tensile, three-point bending and in-plane shearing tests were performed to evaluate the composite mechanical properties. Based on the mechanical tests, the optimum processing conditions were determined. Dynamic mechanical analysis (DMA) was used to measure the thermal-mechanical properties of composites. The sound absorption and sound insulation performance was evaluated. The correlation between mechanical properties and acoustical behavior was also verified by the panel resonance theory.

关键词： Automotive industry

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Epidermal Electronics: Materials and Optimized Designs for Human‐Machine Interfaces Via Epidermal Electronics (Adv. Mater. 47/2013)

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Advanced Materials 2013年第47期25卷

作者： Jae‐Woong Jeong Woon‐Hong Yeo Aadeel Akhtar James J. S. Norton Young‐Jin Kwack Shuo Li Sung‐Young Jung Yewang Su Woosik Lee Jing Xia Huanyu Cheng Yonggang Huang Woon‐Seop Choi Timothy Bretl John A. Rogers Department of Materials Science and Engineering Beckman Institute for Advanced Science and Technology and Frederick Seitz Materials Research Laboratory University of Illinois at Urbana‐Champaign Urbana Illinois 61801 USA Medical Scholars Program Neuroscience Program University of Illinois at Urbana‐Champaign Urbana Illinois 61801 USA Neuroscience Program University of Illinois at Urbana‐Champaign Urbana Illinois 61801 USA School of Display Engineering Hoseo University Asan 336‐795 Republic of Korea Department of Mechanical engineering Pohang University of Science and Technology Pohang 790‐784 Republic of Korea Center for Mechanics and Materials Tsinghua University Beijing 100084 China Department of Civil and Environmental Engineering Department of Mechanical Engineering Center for Engineering and Health Northwestern University Evanston Illinois 60208 USA Department of Engineering Mechanics Tsinghua University Beijing 100084 China Department of Civil and Environmental Engineering Department of Mechanical Engineering Center for Engineering and Health Northwestern University Evanston Illinois 60208 USA Department of Civil and Environmental Engineering Department of Mechanical Engineering Center for Engineering and Health Northwestern University Evanston Illinois 60208 USA Department of Aerospace Engineering University of Illinois at Urbana‐Champaign Urbana Illinois 61801 USA Department of Materials Science and Engineering Beckman Institute for Advanced Science and Technology and Frederick Seitz Materials Research Laboratory University of Illinois at Urbana‐Champaign Urbana Illinois 61801 USA

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Fatigue strength of friction-stir-welded joint of 2024-T3 aluminum alloy (Particles as origin of fatigue failure)

Fatigue strength of friction-stir-welded joint of 2024-T3 al...

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10th International Conference on Technology of Plasticity, ICTP 2011

作者： Ariumi, R. Asakawa, M. Okada, T. Nakamura, T. Machida, S. Department of Applied Mechanics Graduate School of Fundamental Science and Engineering Waseda University Tokyo Japan Department of Applied Mechanics and Aerospace Engineering Waseda University Tokyo Japan Aviation Program Group Japan Aerospace Exploration Agency Japan

ISBN: (纸本)9783514007840

In this study, cyclic loading experiments and metallographical observation with scanning electron microscopy were conducted to clarify the fatigue life and the origin of fatigue failure of friction-stir-welded (FSW) 2024-T3 aluminum alloy sheet (t = 2 mm) and base material. The observation revealed that FSW specimens were fractured by particles as well as the base metal. The fracture occurred away from the weld area, and the FSW specimen had a fatigue life that was comparable to that of the base metal. The metallographical observation revealed that bigger particles in the stirred area were observed much less frequently compared to the rest of the area. Particle distribution in other areas was similar, regardless of the distance from the center of the weld. On the basis of these findings, we conclude that polished FSW joints have a fatigue life similar to polished base metal. © 2011 IBF (RWTH Aachen) & IUL (TU Dortmund).

关键词： Fatigue of materials

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Adhesion selectivity by electrostatic complementarity. I. One-dimensional stripes of charge

Adhesion selectivity by electrostatic complementarity. I. On...

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作者： Bai, Ying Jin, Congrui Jagota, Anand Hui, C.-Y. Department of Chemical Engineering Lehigh University Bethlehem PA 18015 United States Bioengineering Program Lehigh University Bethlehem PA 18015 United States Field of Theoretical and Applied Mechanics Sibley School of Mechanical and Aerospace Engineering Cornell University Ithaca NY 14850 United States Institut für Neue Materialien Saarbrücken Germany

Highly enhanced and selective adhesion can be achieved between surfaces patterned with charges even when each one has no net charge. In this and a companion paper [C. Jin, Y. Bai, A. Jagota, and C.-Y. Hui, J. Appl. Phys. 110, 054903 (2011)] we analyze the possibility of adhesion selectivity between two flat surfaces patterned with stripes of surface charge chosen such that each surface initially carries no net charge. A few combinations, with appropriately matching strip widths, are predicted to adhere to each other. We also find that the deformability of the materials plays a critical role in defining the range of patterns that recognize each other, i.e., their selectivity. With increasing compliance, a significant enhancement of adhesion can be achieved by deformation that allows better matching between charge patterns. © 2011 American Institute of Physics.

关键词： Adhesion

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Development of a Multiple-Lumen Nerve Cuff Utilizing Growth Stimulant Patterns for Controlled Regeneration

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MRS Online Proceedings Library 2011年第1期550卷 303-312页

作者： Y. S. Chen C. Miller M. H. Greer M. Quinones R. T. Greer Biomedical Engineering Program Iowa State University Ames USA Department of Biomedical Sciences Iowa State University Ames USA Department of Veterinary Clinical Sciences Iowa State University Ames USA Department of Aerospace Engineering and Engineering Mechanics Iowa State University Ames USA

Silicone rubber multiple-lumen (ML) nerve cuffs were used for side-by-side comparisons of the effectiveness of two varieties of nerve growth stimulants (collagen gel and a gel mixture of collagen, fibronectin, and laminin) for regenerating cables across a 15 mm gap in 10 adult Sprague-Dawley rats. The filling pattern of the six tubes of the multiple-lumen portion of the cuff alternated with the collagen gel and the gel mixture of collagen, fibronectin, and laminin. After an 8 week implantation period, 53% (32 of 60) of the 0.5 mm diameter lumens displayed successful cable regeneration for both material fillings. The ML cuff experiments demonstrate the ability to bridge a 15 mm gap in the sciatic nerve of the rat by 8 weeks for relatively small diameter conduits in ML cuffs loaded with two varieties of growth stimulants. A more advanced organization including a smaller acellular region fraction and a higher vascularity is seen in the cables from the mixture-filled lumens compared to those in the cables from the collagen-filled lumens.

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Analytical, experimental and computational viscoelastic material characterizations absent Poisson's ratios

Analytical, experimental and computational viscoelastic mate...

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52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

作者： Michaeli, Michael Shtark, Abraham Grosbein, Hagay Steevens, Andrew J. Hilton, Harry H. Department of Mathematics Bar-Ilan University Ramat Gan 52900 Israel R and D - Structures Analysis Team IMI POB 1044 Ramat Hasharon 47100 Israel Aerospace Engineering Department College of Engineering University of Illinois at Urbana-Champaign 104 S. Wright Street Urbana IL 61801-2935 United States Private Sector Program Division National Center for Supercomputing Applications University of Illinois at Urbana-Champaign 104 S. Wright Street Urbana IL 61801-2935 United States US Army Corps of Engineers Construction Engineering Research Laboratory Champaign IL 61821 United States Department of Aerospace Engineering National Center for Supercomputing Applications United States Computational Structural/Solid Mechanics National Center for Supercomputing Applications United States

ISBN: (纸本)9781600869518

The objective is to formulate numerical implementations of analytical and experimental protocols to determine linear viscoelastic material properties without using Poisson's ratios, as devised in [1 - 3]. The presented analysis is in terms of 3-D generalized viscoelastic constitutive relations with hereditary integrals and relaxation moduli or creep compliances. The numerical procedures are based on experimental data from photogrammetric and tensile testing instrumentations, which provide stress data in the 1-D loaded direction and strains in both longitudinal and transverse directions. Measurements and data analyses include the entire time range of starting transient and steady-state loading conditions. The paper presents implementations of solutions for the linear case, where the relaxation time values are prescribed according to schemes of [1 - 3]. Convergence of the Prony series representations is evaluated. The full nonlinear determination of the relaxation times is also derived. Analytical simulations of experiments are formulated and evaluated to determine the accuracy of fit of the new protocol and and to evaluate experimental data. Copyright © 2011 by M. Michaeli, A. Stark, H. Grosbein, A. J. Steevens and H. H. Hilton.

关键词： Viscoelasticity

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Investigation on Twisting and Side Wall Opening Occurring in Curved Hat Channel Products Made of High Strength Steel Sheets

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AIP Conference Proceedings 2011年第1期1383卷 887-894页

作者： Masato Takamura Ayako Fukui Hiroshi Yano Takayuki Hama Hideyuki Sunaga Akitake Makinouchi Motoo Asakawa aVCAD System Research Program RIKEN 2‐1 Hirosawa Wako‐shi Saitama 351‐0198 Japan bGraduate School of Fundamental Science and Engineering Waseda University Tokyo Japan cUNIPRES Corporation Yokohama Japan dDepartment of Energy Science and Technology Kyoto University Kyoto Japan eDepartment of Applied Mechanics and Aerospace Engineering Waseda University Tokyo Japan

High strength steel sheets are becoming increasingly important for the weight reduction of automotive bodies to meet the requirements for reduced environmental impact. However, dimensional defects resulting from springback are serious issues, and effective methods of predicting and reducing such defects are necessary. In this study, we numerically and experimentally analyzed the mechanisms of dimensional inaccuracies caused by springback occurring in curved hat channel deep drawing products. The analysis was based on the static explicit FEM software “TP‐STRUCT” (the solver part is known as “STAMP3D”). The results of the experiments and simulations similarly show that the twist angle is positive (right‐hand system) when the drawing height is relatively large. We calculated the twist torque around the longitudinal axis using the stress distributions obtained by FE analysis. Through the investigation of twist torque and its transition during the drawing and die removal processes, we found that the negative torque generated by side wall opening occurring in the die removal process is the dominant factor of the positive twist. Knowing such mechanisms of twist in cases with a relatively large drawing height, we attempted to explore methods of reducing side wall opening by giving the side wall a stepped shape with the eventual aim of reducing twist. Consequently, we concluded that the stepped shape on the side wall has marked effects of reducing side wall opening, mainly through the elimination of bending‐unbending effects on die shoulders, which was verified by observing the stress distribution obtained by FE analysis.

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Help on SOS [Ask the Experts]

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IEEE Control Systems 2010年第4期30卷 18-23页

作者： Ufuk Topcu Andy Packard Peter Seiler Gary Balas Mechanical Engineering Department University of California Berkeley USA California Institute of Technology USA Aerospace Engineering and Mechanics Control Science and Dynamical Systems program University of Minnesota USA Aerospace Engineering and Mechanics Department University of Minnesota USA Research and Development Honeywell International Inc. USA

In this issue of IEEE Control Systems Magazine, Andy Packard and friends respond to a query on determining the region of attraction using sum-of-squares methods.

关键词： Polynomials Symmetric matrices Convergence Yield estimation Control theory Matrix decomposition

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Evaluation of FSW Fatigue Crack Growth Rate Based on Crack Closure Phenomenon

Evaluation of FSW Fatigue Crack Growth Rate Based on Crack C...

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2010亚太航空航天技术研讨会

作者： Shinya Fujita Takao Okada Motoo Asakawa Kazuya Kuwayama Toshiya Nakamura Shigeru Machida Major in Applied Mechanics Graduate School of Fundamental Science and EngineeringWaseda UniversityTokyoJapan Aviation Program Group Japan Aerospace Exploration AgencyTokyoJapan Department of Applied Mechanics and Aerospace Engineering Waseda UniversityTokyoJapan

The purpose of thisstudy is to evaluate the crack closure phenomenon of 2024-T3 aluminum alloy panel and the FSW panel joined by the *** attention on crack opening stress,its calculation using elasto-plastic FEM is conducted to clarify the influence of residual stress on crack opening *** calculated crack opening stress of base material and the FSW panel are in close agreement with the measured *** the FEM results show that the part of crack faces around FSW weld line is opened by tensile residual stress despite no external *** behavior conforms qualitatively to that of test *** da/dN—（?）K curves for FSW panel are obtained using the crack growth test results of base material and the calculated crack opening stress for base material and the FSW *** obtained curve conformed to the experimental result,indicating the crack growth rate of FSW panel could be predicted quantitatively by evaluating crack opening stress in elasto-plastic FEM.

关键词： Fatigue Crack Propagation Property 2024-T3 Aluminum Alloy Friction Stir Welding FEM

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Help on SOS

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IEEE CONTROL SYSTEMS MAGAZINE 2010年第4期30卷 18-23页

作者： [Anonymous] University of California at Berkeley (UCB) Mechanical Engineering Department United States California Institute of Technology United States Aerospace Engineering and Mechanics Department University of Minnesota United States Control Science and Dynamical Systems Program University of Minnesota United States

Andy Packard, an expert from University of California at Berkeley (UCB) Mechanical engineering Department shares views on the use of sum-of-squares (SOS) methods to determine the region of attraction (ROA). SOS applies to polynomials in several real variables and a polynomial is a finite linear combination of monomials. The ROA can be visualized by simulating the system from many initial conditions and plotting the trajectories in a phase plane plot for systems with two or three states. SOS techniques can be used to perform nonlinear analyses, including computation of input/output gains, estimation of reachable sets, and computation of robustness margins. The approaches that apply to SOS methods includes the computational requirements that grow rapidly in the number of variables and polynomial degree, which roughly limits SOS-based analysis to systems with at most eight to ten states, one to two inputs, and polynomial vector fields of degree 3.

关键词： Polynomials

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