Evolution and interaction of surface cracks under thermal shock load
Thermal cracks would be easily formed on the surface of material under thermal shock. To investigate the thermal crack evolution behavior, the cyclic thermal shock test is applied and the finite element simulation is proposed to study the thermal stress field and the interactions between thermal cracks. Test results show that the thermal cracks nucleate on the specimen surface largely and finally form in stable thermal crack network. The length of the cracks could reach several millimeters, however, their depth is only about hundreds of microns. Simulation results show that large temperature and thermal stress gradient would occur in the cooling process, and the higher the cooling speed the higher the maximal thermal stress. Parallel and coplanar cracks both reflect weak interactions in crack shielding and enhancing effect, respectively. And the influence factors are also modeled in different crack distributions. All the simulation results agrees well with the experiment.