Stress resistance parameters of brittle solids under laser/plasma pulse heating

The present study analyses the stress and fracture response of brittle mate rials under the effect of high-power pulse laser/plasma sources. It establi shes the relationship between the material properties and the degree of fra cture damage and threshold loading parameters which initiate fracture. The crack stability is analyzed using the generalized fracture mechanics approa ch for a non-uniform stress distribution. The thermal stress field is deter mined using a quasi-static thermomechanical diagram appropriate for a pulse d heating under a uniaxial temperature variation. The stress intensity fact or is calculated for a crack propagating in the stressed layer considered t o be much smaller compared to the body dimensions. The calculations show th at stress intensity versus crack length curves display maxima which allow o ne to determine the critical conditions under which the existing cracks sta rt to propagate and the advancing cracks are arrested. The results are used to evaluate the thermal stress resistance and the degree of fracture damag e as a function of thermal and mechanical properties of materials and the i ntensity and duration of thermal shock loading. The critical temperature va riation within which the crack stability is independent of the crack size i s established. The relation of this parameter to the thermomechanical prope rties of materials is discussed. (C) 2000 Elsevier Science S.A. All rights reserved.