A continuum damage mechanics-based unified creep and plasticity model for solder materials精品.pdfVIP

Available online at ScienceDirect Acta Materialia 83 (2015) 160–168 /locate/actamat A continuum damage mechanics-based unified creep and plasticity model for solder materials Yao Yao,a,⇑ Xu He,a Leon M. Keerb and Morris E. Finec aSchool of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi’an 710072, China bDepartment of Mechanical Engineering, Northwestern University, 2145 Sheridan Rd., Evanston, IL 60208, USA cDepartment of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL 60208, USA Received 13 June 2014; revised 29 September 2014; accepted 29 September 2014 Available online 22 October 2014 Abstract—A nonlinear continuum damage mechanics model is developed for both lead-rich and lead-free solder materials. A unified creep–plasticity constitutive relationship is adopted to simulate the inelastic behaviors; both isotropic and nonlinear kinematic hardening are considered. A tradi- tional continuum damage evolution law is a function of actual damage parameter and effective accumulated plastic strain. In the current work, abso- lute temperature is introduced into the damage model to reflect the effect of temperature on the accumulated damage mechanism. The mechanical properties of solders, incorporating damage initiation and accumulation, were analyzed based on the model developed. Fatigue life under fully reversed cycling is investigated by monitoring the change in peak stresses, which decreases