OSCILLATORY INSTABILITY IN THERMAL-CRACKING - A FIRST-ORDER PHASE-TRANSITION PHENOMENON

The transition between straight and oscillatory crack propagation is analyzed by simulation of the phenomenon by means of the finite element method. The amplitude of a given undulating crack was found to either increase or decrease in propagation depending on the velocity of the cooling front and the temperature difference. The morphological phase diagram and wavelength obtained in this way are compared with the results of linear stability analyses and experimental data in literature. The postcritical behavior is characterized by a jumplike loss of stability analogous to first-order phase transitions.