A unified viscoplastic description of 63Sn-37Pb solder alloy under cyclic straining and stressing

A unified viscoplastic constitutive model for the fatigue life prediction of solder alloy 63Sn-37Pb is presented. The model incorporates the strain rate effect, the creep-plastic interaction and the dwell time effect under cyclic strain and stress loading. The applicability of this constitutive model is examined with cyclic strain tests with different strain rates, and cyclic stress tests under different stress waveforms in order to verify the progressive viscoplastic deformation of 63Sn-37Pb solder alloy. The investigation reveals that the material constants in the constitutive model can be determined by performing simple tests such as creep and cyclic tension-compression loading. The predictions using the constitutive model are found to agree well with the experimental results of the solder alloy under different loading. The agreement demonstrates that the model can satisfactorily describe the viscoplastic deformation behaviour under cyclic strain loading or stress loading.