Analysis of thermal expansion in elastic and elastoplastic layers subjected to cyclic thermal loading

Thermal expansion of a Cu/Si3N4/Cu layered structure was studied by actual measurement and finite element analysis. Thicker Cu and subjecting the samples to cyclic thermal loading increase the thermal expansion of the layered structure. Strain-controlled cyclic tension/compression tests in Cu were performed to obtain the characteristics of cyclic plasticity. A multi-linear kinematic hardening model was applied to represent the elastoplasticity of Cu. Two sets of material parameters were determined: One set from the initial and a second set from the stabilized stress–strain relationship, respectively. It was demonstrated that the determined material parameters allow accurate prediction of the thermal expansion coefficient within 1 ppm/°C for structures subjected and non-subjected to cyclic thermal loading.