Papers by Keyword: Stress-Strain Curve

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Authors: Suttirat Punyamueang, Vitoon Uthaisangsuk
Abstract: The advanced high strength (AHS) steels, for example, dual phase (DP) steels, transformation induced plasticity (TRIP) steels and complex (CP) steels principally exhibit multiphase microstructure features. Thus, mechanical behavior of the constituent phases significantly affects the resulting overall properties of such AHS steels. Novel material characterization techniques on micro- and nano-scale have become greatly more important. In this work, stress-strain response of the DP steel grade 1000 was determined by using the Nanoindentation testing. The DP steel showed the microstructure containing finely distributed martensite islands of about 50% phase fraction in the ferritic matrix. The nano-hardness measurements were firstly performed on each individual phase of the examined steel. In parallel, finite element (FE) simulations of the corresponding nano-indentation tests were carried out. Flow curves of the single ferritic and martensitic phases were defined according to a dislocation based theory. Afterwards, the load and penetration depth curves resulted from the experiments and simulations were compared. By this manner, the proper stress-strain responses of both phases were identified and verified. Finally, the effective stress-strain curve of the investigated DP steel could be determined by using 2D representative volume element (RVE) model.
Authors: Yun Hee Lee, Jong Seo Park, Seung Hoon Nahm, Yong Hak Huh
Abstract: A nondestructive rod compression has been proposed as a new strength characterizing technique for in-service components. Using electrical discharge machining, milling machining, and stamping, it was possible to machine small rods, typically about 0.5 mm in both diameter and height on the target surface. Static compressions of the rods were carried out using a flat punch and their deformation behaviors were recorded as load-displacement curves. Referring to initial dimension of the rods, engineering stress-strain curves implying the yield strengths were calculated from the deformation curves. Surface yield strengths from the rod compressions were directly compared with reference compression results and their slight discrepancies were discussed from the influences of pre-deformation and damage of the rod and additive compliance of the base.
Authors: Yan Ru Li
Abstract: On the basis of diffusion mechanism of crack and stress-strain of concrete, the mathematical differential formula and the pure theoretical model of stress-strain complete process of concrete are established. It is shown that stress-strain relationship of concrete is affected by Hooke’s law and diffusion mechanism of crack, and the law of which can be expressed by an exponential formula.
Authors: Pei Ye, Chang He Wu, Zhan Fang Liu
Abstract: In this paper, an attempt has been made to study the dynamic mechanic properties of vulcanized rubber material which is used for industrial structure. A split Hopkinson pressure bar (SHPB) is utilized to obtain uniaxial compression response of the vulcanized rubber material under different strain-rate and temperatures loading conditions. The stress-strain curves under different conditions are obtained, which can be used as a basis for the data analysis procedure. It is found that the dynamic compressive strength of vulcanized rubber improves with the increase of strain-rate. And it is also significantly higher at low temperature than that at normal temperature,which is opposite from stiffness. Vulcanized rubber exhibits excellent superelasticity at temperature of -40°C that is noted as well.
Authors: Nokeun Park, Sunisa Khamsuk, Akinobu Shibata, Nobuhiro Tsuji
Abstract: This study using a 6Ni-0.1C steel confirmed the relationship between the change in a fraction of dynamically transformed ferrite and the dynamic softening in stress-strain curve during dynamic transformation above ortho-equilibrium austenite-to-ferrite transformation temperature. Dynamic softening in stress-strain curve was well-fitted with a form of Avrami equation as a function of strain, and it corresponded with the change in fraction of ferrite. The slope of work-hardening rate was increased due to the additional softening phenomenon, i.e. dynamic transformation, to dynamic recovery of austenite. Dynamic softening of austenite, which has been considered as a typical evidence of dynamic recrystallization, could be interpreted as a response of dynamic transformation to ferrite.
Authors: Shinji Tanimura, Nobusato Kojima, Terumi Yamamoto, Kouki Yamaji
Authors: Chang Jiang Xiao, Heng Tao Zhang, Ling Yan Zhu, Zheng Xin Li
Abstract: 100 Nm BaTiO3 Powders with the Content of 0, 0.5, 1, 5, 10 and 20% were Added into 1μm Al2O3 Powders, Dense Al2O3-Based Composites with Dispersed BaTiO3 Particulates were Fabricated by Conventional Pressure-Less Sintering at 1500°C. the Results Showed that there is a Non-Linear Relationship between the Addition Content of Fine-Grained Particles and the Flexural Strength of Al2O3 Ceramic. when the Content of Doping BaTiO3 Powders Reached around 5 % (mol), the Maximum Vickers Hardness of 137 and the Highest Break Strength of 269MPa were Achieved. Moreover, the Stress-Strain Curves have the same Characteristics of Ceramics.
Authors: Wan Yusmawati Wan Yusoff, Azman Jalar, Norinsan Kamil Othman, Irman Abdul Rahman
Abstract: The aim of the research was to establish the relationship between stress-strain behaviour of single die Quad Flat No lead (SDQFN) and degradation by gamma irradiation. The SDQFN was exposed to Cobalt-60 with different doses from 0.5 Gy, 1.5 Gy, 5.0 Gy, 10.0 Gy and 50.0 kGy. The three-point bending technique was used to measure the flexural stress and strain of the package behaviour relations. After exposing with gamma radiation, the result showed the decreasing in the strength of the package behaviour of irradiated SDQFN when increasing the dose of gamma irradiation. The highest gamma irradiation dose used in this work produced the highest change in stress-strain behaviour of irradiated SDQFN.
Authors: Siaw Yah Chong, Khairul Anuar Kassim, Kenny Tiong Ping Chiet
Abstract: Previous researchers reported that problematic soft clay can be improved by deep lime stabilization. However, due to low confining pressure of surrounding soil, problems often occurred at top part of column which reduced the performance of lime column, such as: crushing at column head and higher settlement for surrounding soil at the upper part of column. Geotextile encapsulated lime column (GELC) was proposed in this study. The stresses on column are essential in the analysis on columnar improved soil. Multi-stage loading test was conducted on lime column and GELC stabilized Pontian marine clay aged 14 days, 28 days and 56 days in order to investigate axial stress on lime column and GELC stabilized Pontian marine clay. Geotextile encapsulation increased the compressive strength of lime column about 70 percent at axial strain of 8 percent.
Authors: Teruto Kanadani, Norihito Nagata, Keiyu Nakagawa, Koji Murakami, Makoto Hino
Abstract: In this study, the effect of heat treatment conditions and small addition of Cu on occurrence of serration in Al-Si alloys was investigated. Specimens were aged for various times up to 87ks at 273K or 473K after quenching from 853K, and tensile-tested at room temperature. In the binary alloy, serration was observed even after aging for 87ks at 273K, while in the case of aging at 473K, serration did not occur under aging conditions at aging time, tA≧20s. On the other hand, serration was observed even after aging for 72ks at 473K in the Cu-added alloy. In both alloys, serration was also recognized when the specimens were furnace-cooled from 853K to room temperature. Thus, for aging at 473K of the binary alloy serration was observed only when the aging period was short enough, but addition of Cu to the binary alloy prolonged the aging period where serration could be recognized. Aging rate of both alloys measured by tensile strength was almost the same. The size of precipitates in the Cu-added alloy was smaller than that in binary alloy. Moreover, the number of the precipitates at the grain boundary in the Cu-added alloy was smaller than that in the binary alloy. It is considered that serration occurs for Al-Si alloys when the specimen is heat-treated so that small precipitates may be formed. Now the details of the effect of Cu addition are not clear.
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