DEFORMATION AND FAILURE MECHNISM OF THIN-PLATE UNDER COMBINED LASER HEATING AND PRE-STRESS

摘要

A new analysis method has been developed to study the transient response of a thermal-viscoplastic thin-plate made of 4340 steel and 2024-T351 aluminum subjected to constant plane-stress loading and to rapid laser heating. A continuum statistic damage and a thermodynamic damage model are implemented into the constitutive equation of materials. This model can be used to determine parameters related to the critical rupture initiation of materials subjected to deposited laser energy, loading, and duration of heating. The threshold time of heating and threshold temperature of material for laser thermal heating coupled with the tensile stresses causing the structural failure are calculated. The results show that there exist three types of deformation and failure modes in structure under laser heating and pre-stress: rapid rupture, no rupture and delayed rupture according to the duration of the laser heating. In general, the higher the pre-stress level and the higher the laser power density, the shorter the rupture time of the material. The pre-stress level can significantly effect the damage evolution, while the influence of laser power density on damage is relatively minor.