Crack propagation induced by thermal shocks in structured media

This paper describes the propagation of an edge crack in a structured thermoelastic solid. A rapid change of temperature, represented by a time-periodic series of high-gradient temperature pulses, is applied at the boundary of the structured solid. A lattice approximation is employed in the model analysis discussed here. In order to describe the crack advance through the lattice a failure criterion is imposed, whereby the links break as soon as they attain a critical elastic elongation. The elongations of the links are produced both by a variation in temperature and by elastic waves generated at the boundary due to thermal shocks, as well as waves created by the propagating crack through the breakage of the elastic ligaments. The analysis is compared to the quasi-static and dynamic models of thermal striping in thermally loaded solids containing edge cracks. The emphasis is on the effect of the structure on the crack trapping. The nonlinear simulations presented in this paper show that the average speed of crack propagation can be estimated from the analysis of the dispersion properties of waves initiated by the crack. Temperature and inertia contributions to crack propagation are also investigated. It is found that inertia amplifies the elongations of the links, and thus influences the crack advance through the structured solid.