The Method Of Estimation The Material Local Strength And Deformation Behaviors Properties

A majority of the applications for engineering materials involve the use of heterogeneous materials and structures, such as welded joints, that exhibit heterogeneity on a global or a local lever. The global properties of the heterogeneous materials were determined by the uniaxial tensile test, but the local properties are important to improve the process, analyses the loading strength and the deformation behaviors, then it is necessary to determine the local mechanical properties of the materials.A double-hole microshear test method is presented to estimate the local mechanical strength of the heterogeneous materials in this paper. Firstly, the double-hole microshear test are done repeatedly, analyses the factor that influence the precisions, and evaluate the repetitiveness of the test. Choose three kinds of the different materials, pipeline steel, pure copper and 6063 aluminum, carried on the double-hole microshear test and uniaxial tensile test separately. Draw the conclusion that the relationship between the shear yield strength and yield strength, between the ultimate shear strength and the ultimate strength. Then have carried the double-hole microshear test on the local area of the undermached pipeline steel welded joints. On the base of the test create the finite element model, had analyzed the mechanical process of the double-hole microshear test, simultaneity had analyzed the shape of the indenter how to influence the result of the test. In virtue of the finite element model, gained the constitutive property of the material, i.e. the true stress-true strain curve by the finite element inverse method. For improving the efficiency of the deformation behaviors of the materials by the double-hole microshear test, combining the true stress strain curve by the tensile test and the curve inverse method to obtain the strain harden exponent n.