An anisotropic model of continuum damage mechanics has been developed to predict the creep-fatigue life of solder joints. With the help of the finite element method, the stress, strain, and damage fields of the time-dependent and temperature-dependent solder can be obtained. The main advantages of this model include: (1) It can predict the initial crack location and time and the subsequent crack growth paths; (2) The damage analysis is almost the same as in traditional viscoelastic finite element analysis; (3) It can be applied to a complex structure with any loading; (4) It provides a full-field damage investigation of the structure. This damage theory can be used for various solder joints and also can be applied to analyze the creep-fatigue problems of other ductile and temperature-dependent materials. Extensive experiments including uniaxial creep, uniaxial fatigue, tension-torsion, Moire, and bimaterial tests were performed to validate the new model. These validations and comparisons indicate that this model can predict adequately crack growth paths and fatigue lives of solder joints.
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