Time-dependent deformation and fracture of multi-material systems at high temperature

The present work reports several recent research activities on the time-dependent deformation and fracture performance of multi-material system and structures at elevated temperature. A micro region deformation measuring technique is developed to achieve the full creep strain fields of multi-material systems at high temperature in light of the long-distance microscope and digital speckle correlation method. The mean field approach based on the self-consistent method and the generalized self-consistent method are introduced to predict the time-dependent deformation of the dual-components material system under the creep condition. For the pressure vessels with functionally graded materials under both internal and external pressures, an asymptotic solution for creep stress and strain is derived based on the Taylor expansion series. For the time-dependent fracture issue of multi-material structures, a modified creep crack fracture parameter prediction method for C∗ integral in the mismatched weldments and the particle-reinforced composite is proposed based on the generalized equivalent homogenous model. Finally, time-dependent failure assessment diagram (TDFAD) for multi-material system is derived for defect assessment of structures with various combinations of materials.