Analytical Characterization of Mechanical Properties of Bimetallic Clad Sheets

An analytical method to characterize the anisotropic yield function and the hardening behavior of bimetallic clad sheets utilizing the simple tension test was derived in this work. The sheet considered here was a bimetallic clad of A3003 (1.0mm thickness) and STS439 (0.5mm thickness) sheets. The properties of STS439 were evaluated in advance using specimens with A3003 removed by etching. As for the properties of A3003, the rule of mixture was applied for simple tension test results of the clad sheet obtained along the rolling, transverse and 45 degrees directions. Based on Hill's 1948 yield criterion and the associated flow rule, the bi-axial stress state of each layer introduced during the simple tension test (incurred from different anisotropic properties of composing layers) was analytically obtained for three directions, which were then used to calculate the four anisotropic coefficients. In this work, the clad specimen developed a curved shape normal to the tensile direction within the gauge length (as two layers with different anisotropy glued together under the bi-axial stress). Therefore, the width strain was not directly measured, but indirectly obtained by analyzing an additional simple tension test with a different cross-sectional shape.