On crack-tip cooling during dynamic crack initiation

Abstract

This paper presents a hybrid experimental–numerical treatment of the transient thermoelastic effects around a crack tip, subjected to a dynamic loading. A simple numerical procedure was devised to calculate the transient crack-tip temperature field, in a “one-way” coupled approach. The calculations were carried out in two steps: first the evolution of the volumetric strain is determined by solving the mechanical problem. Next, this strain is converted into a nodal heat generation rate to solve the associated thermal problem for the same geometry. This approach was validated through the comparison of simulated and experimentally determined crack-tip temperatures. The experiments were carried out on instrumented compact compression PMMA specimens. These numerical results confirm and extend previous results concerning crack-tip cooling effects (Rittel, D., 1998a. In: Durban, D., Pearson, J.R.A. (Eds.), IUTAM Symposium on Non-linear Singularities in Deformation and Flow. Kluwer Academic Publishers, Dordrecht, pp. 181–192; Rittel, D., 1998b. Int. J. Solids and Structures 35 (22), 2959–2973). They show the three-dimensional nature of the thermal field, with increased cooling effects at specimen’s mid-thickness. The present results also confirm that adiabatic conditions prevail during the initial stages of the dynamic fracture process. Finally, it is shown that the crack-tip cooling effect characterizes the response of linear thermoelastic materials, regardless of their thermal conductivity.