Volume 24, Issue 6 (November 1996)
Creep Rupture Investigation of 63Sn-37Pb Solder by Experiments and Damage Mechanics
The main purpose of this paper is to investigate the crack growth path and creep rupture life of 63Sn-37Pb bulk solder experimentally by Moiré analysis and theoretically using continuum damage mechanics. In conventional fracture mechanics analysis, a crack growth path is assumed a priori. Fracture parameters such as the J-integral and stress intensity factor are subsequently calculated to predict the crack growth rate and structural life. However, it is often difficult to postulate the correct crack growth path for a complex structure that is subject to complex loading. Continuum damage mechanics is an alternative method that can be used to compute structural life with the important feature that the crack growth path is computed automatically. In this paper we develop a theory for partially reversible creep-fatigue damage. A finite element procedure incorporating this damage theory is developed and used to analyze the response of bulk solder plates with holes. The displacement fields obtained by finite element analysis are compared to the fringe patterns obtained from conventional Moiré experiments. Furthermore, the accuracy of the predicted crack growth paths was investigated by comparison between the maximum damage contours obtained by finite element simulation with the actual crack paths occurring in the laboratory specimens. These comparisons indicate the new continuum damage theory developed herein can adequately predict creep displacements, crack growth paths, and structural life.