Thermal fracture as a framework for quasi-static crack propagation

We address analytically and numerically theproblemofcrackpathprediction in themodelsystem of a crack propagating under thermal loading.We show that one can explain the instability from a straight to a wavy crack propagation by using only the principle of local symmetry and theGriffith criterion.We then argue that the calculations of the stress intensity factors can be combinedwith thestandardcrackpropagationcriteria to obtain theevolutionequation for thecrack tipwithinany loadingconfiguration.Thetheoreticalresultsof thethermalcrackproblemagreewith thenumerical simulations we performed using a phase field model. Moreover, it turns out that the phase-fieldmodel allows to clarify the nature of the transition between straight and oscillatory cracks which is shown to be supercritical.