Deformation and Life Estimates for a Metal Matrix—Spherical Particulate Subjected to Thermomechanical Loading

Abstract

Thermal cycling has been experimentally demonstrated to diminish the performance of many reinforced materials. The coefficient of thermal expansion mismatch is the driving force for the development of high self-equilibrating stresses and strains in the vicinity of the reinforcement. To glean the magnitude of these stresses, a simple geometry, a spherical particulate (SiC) in a spherical domain (aluminum W319) was investigated. A set of partitioned strain rate equations considered temperature dependent material properties for thermal, elastic, mechanical plastic, and creep plastic deformation. The mechanical plasticity model utilized an improved Armstrong-Fredrick kinematic hardening algorithm and a Fisher type rate dependent yield criteria. A hyperbolic sine relation proposed by Dorn (1954, “Some Fundamental Experiments on High Temperature Creep,” J. Mech. Phys. Solids, 3, pp. 85–116) was used to model creep deformation. A multidimensional residual stress state due to cooling from the molten state was considered in the simulations. Two damage parameters, Findley and equivalent plastic strain, were employed to estimate cyclic damage. While the life estimates are crude, they both predict finite lives for reasonable service temperature ranges.