Analytical and experimental studies on the damage evolution of SAC solder alloys

A set of fatigue experiments is carried out, currently at room temperature, with different duration of cycling and, consequently, different levels of damage in the specimens. Various quantities such as the yield stress, the ultimate stress and Young’s modulus, and creep strain rates were considered for the characterization of the degradation of the specimens. Several constitutive equations for the equivalent creep strain rate, namely a NORTON power law, the hyperbolic-sine, the double-power, and the ANAND law, in which the damage variable is introduced as an internal state variable, will be considered. The behavior of a one-dimensional specimen is studied under stress (force-controlled), strain (displacement-controlled), and temperature cycling loading conditions and the related damage evolution is analyzed. Material parameters governing the constitutive equations for creep strain rate are identified based on the obtained experimental results. A hyperbolic-sine creep model with damage parameter for SAC305 is implemented in a commercial FE code ABAQUS with the use of user-defined subroutine (CREEP and USDFLD), and corresponding FE-simulations are carried out.