Measurement and Analysis of Elasto-Plastic Deformation Characteristics of Aluminum Alloy Sheet Subjected to Non-linear Stress Paths Without Intermediate Elastic Unloading

The objective of this study is to investigate whether the material model identified using linear stress path (LSP) experiment can predict the deformation behavior of the material subjected to nonlinear stress paths (NLSPs). First, many LSPs are applied to a test sample (6000-series aluminum alloy sheet A6116-T4) with a nominal thickness of 1.1 mm to measure the contours of plastic work and the directions of the plastic strain rates, \({\mathbf{D}}^{\mathrm{p}}\) . Second, proper yield functions that reproduce the stress points forming counters of plastic work and the directions of \({\mathbf{D}}^{\mathrm{p}}\) are determined. Third, a NLSP is applied to the test sample; the NLSP consists of several linear stress paths without intermediate elastic unloading. Forth, the elasto-plastic deformation behavior of the test sample subjected to the NLSP is compared with that predicted using the yield function determined from the LSP experiment. It is concluded that although the measured \({\mathbf{D}}^{\mathrm{p}}\) slightly deviated from those predicted from the normality flow rule, the deformation behavior of the test sample predicted for the NLSP using the model determined from the LSP experiment is generally consistent with the measurement within the experimental conditions of the present study.