Papers by Keyword: Stress-Strain Curve

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Authors: Yong Hak Huh, Dong Iel Kim, Dong Jin Kim, Philip Park, Chang Doo Kee, Jun Hyub Park
Authors: Xi Jun Liu, Lin Xiang Liu, Yu Mei Wang
Abstract: In order to obtained the constitutive equations of thermal insulation masonry, the four masonry with different angles has pressed. Study on thermal insulation of masonry compressive mechanical parameters of constitutive equation and two-stage by compression stress-strain curves obtained in the servo press machine tests and data processing. The Basic mechanics parameters can be provided for finite element analysis of thermal insulation composite wall. The experiments showed that the constitutive model is discretization and the maximum stress and strain by press machine testing is different from brick masonry. The constitutive model is close with curve by press machine testing. The performance of mechanics in thermal insulation wall can be application by the stress-strain curves of thermal insulation of masonry. The stress-strain curves based experiments can be used finite element analysis of thermal insulation wall.
Authors: Cheng Lin He, Jin Xiang Chen
Abstract: This report reviews biomimetic studies performed in China on the beetle forewing, noting that Chinese scholars studying bionics have substantially advanced various branches of biomimetic research in beetles. The report also proposes the development of branches of bionic research and establishes the foundation for corresponding experiments and theories. Then, using the A. dichotoma forewing as a an example, the cross-sectional shape, orientation of the laminated fiber layers, structure of the trabeculae, and respective mechanical properties of the forewing, as well as their biological significance, are reviewed. 1) The forewing has a lightweight border frame structure and an optimal design of variable cross-sections suitable for different positions, which achieves the specific second moment of inertia required for flight. 2) Due to the non-equiangular, laminated structure of the forewing, there are two types of tensile fracture morphologies: fiber breakage and residual bridging. This study demonstrates the anisotropy and the effectiveness of the forewings tensile strength by analyzing the orientation direction of the fibers. 3) The trabecular structure can be used to efficiently improve the peel resistance of the laminated composites. Based on the above points, possible directions for future work are also indicated in this paper.
Authors: Toshiyuki Koyama, Hidehiro Onodera
Abstract: The secant method proposed by Weng [1] is a practical calculation method to evaluate the stress-strain curve of the two-phase materials, but the shape of the inclusion phase has been often assumed to be a sphere or an ellipsoid in the calculation. In this study, we modified the secant method by utilizing the phase-field micro-elasticity theory [2,3] so as to be able to calculate the SS-curve of the materials consisting arbitrary morphology of microstructure, and applied this method to the conventional microstructures in steels, i.e., the ferrite-bainite two-phase microstructure.
Authors: Hai Wen Luo, Xu Dong Fang, Rui Zhen Wang, Zhan Yin Diao
Abstract: Dynamic recrystallization was studied for the stainless steels with nitrogen contents of 0.56% to 1.08% during hot deformation at temperatures of 900~1200 with strain rates ranging from 0.003 to 42 s-1. It was found that flow stress could increase remarkably with increasing nitrogen content. Flow curves during the deformation by 0.1~42/s at temperatures of 900~1200°C show a single peak, indicating the occurrence of dynamic recrystallization during deformation. The peak strain seems to decrease with increasing N content, suggesting that higher content of N facilitates dynamic recrystallization. The quenched microstructures were analyzed by optical microscopy, EBSD and TEM. The recrystallized grain sizes on the quenched specimens were measured and its dependence on temperature and strain rate was analyzed. At high temperature, continuously dynamically recrystallized microstructures were observed; whilst at low temperature, necklace-like partially recrystallized microstructures were found. Key words: High nitrogen stainless steel; dynamic recrystallization; stress-strain curves
Authors: Hiroyuki Nakayama, Minoru Taya
Abstract: Characteristics of high temperature shape memory alloy in Ti50-Pd(50-x)-W(x) at%, x = 3 and 5 system has been examined. The prepared ingot was homogenized at 1273 K for 86.4 ks followed by water quenched. The homogenized samples were hot-rolled at 1273 K to a plate shape with thickness of 3.5 mm and 1.0 mm. Transformation temperatures were determined by 4-probe electrical resistivity measurement. The transformation behavior in the both samples exhibited similar trend. The first heating curve showed no significant step. In contrast, the first cooling curve exhibited clear step due to martensitic transformation. After second cycle, the transformation behavior was stabilized, thus the clear steps in the cooling and heating curves were seen. Stressstrain curve of hot-rolled plate with 3.5 mm was examined by compression in Ti50-Pd47-W3 at% alloys. The sample exhibited 1 % shape memory effect. By bending test, nearly perfect SME effect was observed in hot rolled Ti50-Pd45-W5 at% alloy plate with thickness of 1 mm.
Authors: Radek Musalek, Tomas Tesar, Josef Strasky, Jaroslav Cech
Abstract: Mechanical properties of two stainless steels (AISI 316L and AISI 410) processed by spark plasma sintering (SPS) were evaluated by four different types of indentation-based tests: hardness mapping, evaluation of indentation stress-strain curves, instrumented indentation and bonded-interface technique. Obtained results showed that the used combination of relatively simple experiments may provide a deeper understanding of mechanical behavior of materials prepared by SPS.
Authors: David Torres Franco, Guillermo Urriolagoitia-Sosa, Guillermo Urriolagoitia-Calderón, Luis Hector Hernandez Gomez, Beatriz Romero Angeles, Vistor Fernando Cedeño Verduzco
Abstract: Until now, the most common way to obtain the stress-strain curves for a material is through axial tensile testing. However, in recent years there have been developments on alternative methods for material characterization. In this sense, the bending procedure has proved to be a powerful technique, which allows simultaneous determination of tension and compression stress behavior by the use of bending moment and strain data. The characterization of materials by means of bending data was presented for the first time in 1910 by the German engineer Herbert. Some years later Nadai and Marin developed some research on this procedure. More recently, several researchers (Mayville and Finnie, Laws and Urriolagoitia-Sosa, have developed diverse bending methods for the simultaneous determination of tension and compression stress-strain curves. In this paper, three bending methods are analyzed and compared against axial tensile and compressive results. It was decided to apply each one of the bending procedures to bent rectangular cross sections beams made from 6063-T5 Aluminum alloy. The specimens were annealed to eliminate previous loading history and axially pulled to induce a controlled anisotropic behavior (strain hardening and Bauschinger effect). The results obtained by two of the three methods provided great confidence and have certified the application of this new technique to characterize material.
Authors: Wei Wang, Hua Ling, Shun De Xu, Xiao Ni Wang
Abstract: Mathematical model for skeleton stress-strain curve under dynamic loading (SSSC) is one important issue to study the dynamic behavior of soft soil. Based on mechanism of developing process, primary mathematical behavior that SSSC model should meet is analyzed. Mathematical investigation on two conventional SSSC models, namely hyperbolic model and exponential model, is conducted. Dynamic stress index is proposed and employed to signalize the shortcomings of two conventional models. A composite tangent-exponent model for SSSC with three parameters is established, which is a monotone increasing and up limited function. The new model can overcome conventional shortcomings. Finally, good agreement between investigated and new model fitted data has been found out.
Authors: Syed H. Riza, S.H. Masood, Cui E Wen
Abstract: The potential of laser assisted Direct Metal Deposition (DMD) process, for creating structures from high strength steel alloys that can be used in engineering applications requiring high strength and greater ductility in combination with high hardness is investigated. Due to increasing interest in metallic honeycomb and sandwiched structures, solid and porous specimens are prepared and examined in similar conditions. Specimen using two different powders of 316L stainless steel and H13 tool steel alloy are generated by DMD cladding on mild steel plates as substrates. The parts are tested under quasi static compressive loading and curves plotted and analysed for stress vs. strain behaviour. The results indicate that at low laser power, solid and porous steel structures with yield strength and ductility comparable to commercial grades can be produced. Porous structures show excellent characteristics suitable for applications in newly developing field of metallic honeycombs and sandwiched structures. Low modulus of elasticity is a matter of concern, but it can be improved by heat treatment.
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