Experimental and numerical study on dynamic mechanical behaviors of low-silver lead-free solder under combined compression-shear loadings

Abstract

In this paper, the behaviors of low-silver lead-free solder Sn0.3Ag0.7Cu were studied by quasi-static and dynamic compression-shear tests and finite-element analysis. The quasi-static tests were performed on MTS-809 material tester, while the dynamic tests were carried out on a modified split Hopkinson pressure bar (SHPB) system that uses inclined cropped cylinders as incident and transmitter bars. The inclination angle, which is formed between the ends of the incident and transmitter bar, allows dynamic combined compression-shear loadings. Inclination angles from 0° to 45° were tested under the same strain rate of 2157 s−1. Experimental results show that a larger inclination angle results in lower normal stress amplitude but higher tangential stress, given the same strain rate. The effect of strain rate was further studied by fixing the inclination angle as 30°. When the strain rate is below 2445 s−1, the strain rate effect is limited. However, from 2445 to 2875 s−1, the strain rate effect becomes significant, not only in normal direction but also in tangential direction. The experimental findings on both inclination angle and strain rate were then simulated by finite element method using the Cowper–Symonds material model. It was found that the adopted material model is able to predict the same trending as experimental data, but an accurate prediction requires a more sophisticated material model.