The Experts below are selected from a list of 109206 Experts worldwide ranked by ideXlab platform
Takeshi Nishiwaki - One of the best experts on this subject based on the ideXlab platform.
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Stress correction method for flow stress identification by Tensile Test using notched round bar
Journal of Materials Processing Technology, 2018Co-Authors: Masanobu Murata, Yoshinori Yoshida, Takeshi NishiwakiAbstract:Abstract In this paper, a stress correction method for flow stress identification using notched round bar Tensile Test is proposed. Flow stress is evaluated in uniform elongation and local elongation until final fracture in a Tensile Test with circumference notched round bar Tensile Test specimens. Tensile load and change in the shape of the notch are measured by image analysis. In order to correct the average Tensile stress to the flow stress, inverse analysis is applied to the Tensile Test. For the validation of the inverse analysis, numerical Tensile Tests are performed by FEM. As a result of applying the inverse analysis for the numerical Tensile Tests, the corrected flow stress completely reproduces the two types of reference flow stress curves which are determined by Swift’s and Voce’s law. On the other hand, the flow stress corrected by Bridgman’s method, which is a conventional stress correction method, overestimated these reference flow stress curves. In the case of the actual Tensile Test of low carbon steel SS400 (in JIS), the flow stress corrected by inverse analysis corresponds to Swift’s law determined in uniform elongation. As well as numerical Tensile Test results, the flow stress corrected by Bridgman’s method is higher than that of obtained by the inverse analysis.
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identification of ductile fracture parameter with stress correction method using notched round bar Tensile Test
Procedia Engineering, 2017Co-Authors: Masanobu Murata, Yoshinori Yoshida, Takeshi NishiwakiAbstract:Abstract A stress correction method is proposed for the identification of flow stress with the circumference notched round bar Tensile Test. Flow stress is evaluated post necking until final fracture in the Tensile Test. Tensile load and change in the shape of the notch are measured by image analysis. In order to correct average Tensile stress to the flow stress, inverse analysis is applied to the Tensile Test results. The proposal stress correction method is applied to two metallic materials; a low carbon steel and an aluminum alloy. In each material, corrected flow stress curves overlapped into a single curve regardless of the initial notch radius. Furthermore, the critical damage values of two kinds of ductile fracture criterion are identified.
Eric Ragneau - One of the best experts on this subject based on the ideXlab platform.
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investigation of the forming limit strains at fracture of aa5086 sheets using an in plane biaxial Tensile Test
Engineering Fracture Mechanics, 2016Co-Authors: Xiao Song, Lionel Leotoing, Dominique Guines, Eric RagneauAbstract:An in-plane biaxial Tensile Test with a dedicated cruciform specimen is performed to determine the forming limit strains at fracture for aluminium alloy 5086. A method based on the evolution of strain in the central area of the specimen and the observation of the macroscopic image of specimen surface is proposed to identify the onset of fracture and the forming limit strains at this moment. The forming limit strains at fracture are determined under different strain paths provided by the two independent axes of the experimental device. Finite element simulations are performed to determine and compare numerical forming limit strains with three ductile fracture criteria (Cockroft and Latham, Brozzo and Ayada). The critical damage values of the criteria are determined by the experimental results under different strain paths.
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Identification of sheet metal hardening for large strains with an in-plane biaxial Tensile Test and a dedicated cross specimen
International Journal of Mechanical Sciences, 2015Co-Authors: Wei Liu, Lionel Leotoing, Dominique Guines, Eric RagneauAbstract:In this work, an in-plane biaxial Tensile Test of cruciform specimen is performed to identify the hardening behaviour of metallic sheets under large strains. Firstly, an optimal shape of the specimen is suggested. Then, a biaxial Tensile Test is carried out for an aluminium alloy AA5086. Experimental forces on the two axes of the specimen are measured during the Test and strains in the central area of the specimen are post-treated by means of Digital Image Correlation (DIC) technique. Finally, by considering different yield criteria, the associated hardening laws are identified thanks to an inverse procedure based on a Finite Element (FE) modeling of the biaxial Tensile Test and on the experimental data mentioned above. The identified biaxial flow curves are then compared with the ones from the classical uniaxial Tensile Test.
Masanobu Murata - One of the best experts on this subject based on the ideXlab platform.
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Stress correction method for flow stress identification by Tensile Test using notched round bar
Journal of Materials Processing Technology, 2018Co-Authors: Masanobu Murata, Yoshinori Yoshida, Takeshi NishiwakiAbstract:Abstract In this paper, a stress correction method for flow stress identification using notched round bar Tensile Test is proposed. Flow stress is evaluated in uniform elongation and local elongation until final fracture in a Tensile Test with circumference notched round bar Tensile Test specimens. Tensile load and change in the shape of the notch are measured by image analysis. In order to correct the average Tensile stress to the flow stress, inverse analysis is applied to the Tensile Test. For the validation of the inverse analysis, numerical Tensile Tests are performed by FEM. As a result of applying the inverse analysis for the numerical Tensile Tests, the corrected flow stress completely reproduces the two types of reference flow stress curves which are determined by Swift’s and Voce’s law. On the other hand, the flow stress corrected by Bridgman’s method, which is a conventional stress correction method, overestimated these reference flow stress curves. In the case of the actual Tensile Test of low carbon steel SS400 (in JIS), the flow stress corrected by inverse analysis corresponds to Swift’s law determined in uniform elongation. As well as numerical Tensile Test results, the flow stress corrected by Bridgman’s method is higher than that of obtained by the inverse analysis.
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identification of ductile fracture parameter with stress correction method using notched round bar Tensile Test
Procedia Engineering, 2017Co-Authors: Masanobu Murata, Yoshinori Yoshida, Takeshi NishiwakiAbstract:Abstract A stress correction method is proposed for the identification of flow stress with the circumference notched round bar Tensile Test. Flow stress is evaluated post necking until final fracture in the Tensile Test. Tensile load and change in the shape of the notch are measured by image analysis. In order to correct average Tensile stress to the flow stress, inverse analysis is applied to the Tensile Test results. The proposal stress correction method is applied to two metallic materials; a low carbon steel and an aluminum alloy. In each material, corrected flow stress curves overlapped into a single curve regardless of the initial notch radius. Furthermore, the critical damage values of two kinds of ductile fracture criterion are identified.
Peter Tiernan - One of the best experts on this subject based on the ideXlab platform.
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design optimisation of biaxial Tensile Test specimen using finite element analysis
International Journal of Material Forming, 2014Co-Authors: Peter Tiernan, Alan HannonAbstract:One of the most restricting aspects of the biaxial Tensile Test for sheet metal is the design of the cruciform specimen. Although specimens of the cruciform type have been investigated quite extensively previously, no standard geometry for the cruciform specimen exists. Using a specifically designed pantograph apparatus for operation in a standard Tensile Testing machine, various cruciform specimens machined from low-carbon cold rolled steel sheet were analysed experimentally. Finite element modelling of the specimens was conducted in parallel to the experimental Test programme to establish optimum specimen geometry. Through a process of optimisation, a standard cruciform specimen was designed which can be used to accurately predict the mechanical behaviour of the mild steel when formed in multiple directions simultaneously. This paper describes the optimisation process and the results obtained from both the experimental Testing and numerical modelling.
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a review of planar biaxial Tensile Test systems for sheet metal
Journal of Materials Processing Technology, 2008Co-Authors: Alan Hannon, Peter TiernanAbstract:Abstract The focus of this paper is to present a comprehensive review of the main biaxial Test systems that have been developed with primary focus on sheet metal Testing. The paper includes a review of biaxial Tensile Test devices and specimen design for biaxial Testing. A description of the scientific significance of the work and the industrial implications arising from results of biaxial Testing is also presented. Biaxial Testing of metal is becoming prevalent in the sheet metal working industry for establishing the mechanical properties of the sheet material. The primary reason for using the biaxial Tensile Test, as opposed to the common uniaxial Test, is that metal in sheet form is largely anisotropic, i.e. it has varying mechanical strength in different directions due to the forming process used in its manufacture. As the standard Tensile Test only determines the mechanical properties in one direction the resulting Test data may not be applicable to multi-directional forming processes such as deep drawing. Biaxial Testing is also becoming increasingly important for Testing of metals used in machine and structural components that may be typically loaded in more than one direction during service. Biaxial loading can cause failure of the material at loads much less than that determined by conventional Tensile-Testing methods. The aforementioned reasons have led to research activity in the area of biaxial Testing.
Wei Liu - One of the best experts on this subject based on the ideXlab platform.
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calibration of anisotropic yield function by introducing plane strain Test instead of equi biaxial Tensile Test
Transactions of Nonferrous Metals Society of China, 2018Co-Authors: Jie Zhu, Wei Liu, Shangyu Huang, H U Jianhua, Xifan ZouAbstract:Abstract The equi-biaxial Tensile Test is often required for parameter identification of anisotropic yield function and it demands the special Testing technique or device. Instead of the equi-biaxial Tensile Test, the plane strain Test carried out with the traditional uniaxial Testing machine is suggested to provide the experimental data for calibration of anisotropic yield function. This simplified method by using plane strain Test was adopted to identify the parameters of Yld2000-2d yield function for 5xxx aluminum alloy and AlMgSi alloy sheets. The predicted results of yield stresses, anisotropic coefficients and yield loci by the proposed method were very similar with the experimental data and those by the equi-biaxial Tensile Test. It is validated that the plane strain Test is effective to provide experimental data instead of equi-biaxial Tensile Test for calibration of Yld2000-2d yield function.
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Identification of sheet metal hardening for large strains with an in-plane biaxial Tensile Test and a dedicated cross specimen
International Journal of Mechanical Sciences, 2015Co-Authors: Wei Liu, Lionel Leotoing, Dominique Guines, Eric RagneauAbstract:In this work, an in-plane biaxial Tensile Test of cruciform specimen is performed to identify the hardening behaviour of metallic sheets under large strains. Firstly, an optimal shape of the specimen is suggested. Then, a biaxial Tensile Test is carried out for an aluminium alloy AA5086. Experimental forces on the two axes of the specimen are measured during the Test and strains in the central area of the specimen are post-treated by means of Digital Image Correlation (DIC) technique. Finally, by considering different yield criteria, the associated hardening laws are identified thanks to an inverse procedure based on a Finite Element (FE) modeling of the biaxial Tensile Test and on the experimental data mentioned above. The identified biaxial flow curves are then compared with the ones from the classical uniaxial Tensile Test.
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effect of intermetallic compounds on fracture behaviors of sn3 0ag0 5cu lead free solder joints during in situ Tensile Test
Journal of Materials Science: Materials in Electronics, 2012Co-Authors: Yanhong Tian, Wei Liu, Wei Zhang, Lina Niu, Chunqing WangAbstract:In this paper, in situ Tensile Tests under various amounts of deformation were performed on Sn3.0Ag0.5Cu lead-free solder joints subjected to multi-reflow and isothermal aging processes by using a scanning electron microscope. Microstructure evolution and deformation behavior of the solder joints were observed. Effects of the intermetallic compound (IMC) Cu6Sn5 on fracture behaviors of the solder joints were investigated. Results showed that the Sn3.0Ag0.5Cu lead-free solder joints contained only a few Sn grains, and the sequence and degree of plastic deformation varied for the different grains in the same solder joint due to the strong anisotropic properties of Sn grains. Further experiments revealed that plastic deformation occured primarily in the form of slip bands in the solder joints during the in situ Tensile Test. Various fracture modes including intergranular and phase boundary fractures were observed. The fracture behaviors of solder joints were significantly affected by morphologies and distributions of the Cu6Sn5 IMCs. It was found that Cu6Sn5 particles located at the grain boundaries are apt to become crack sources, and that the long rod shaped Cu6Sn5 were easily broken. However, spherical Cu6Sn5 hardly deformed during the Tensile Test, resulting in dynamic recrystallization. In this case, fracture occured at the sub-grain boundaries.
