激光作用金属板材的温度场和热应力场

基于Von Mises屈服准则和弹塑性本构关系,建立了连续激光辐照金属基体材料的空间轴对称有限元模型.该模型考虑了金属材料在激光作用过程中的热学及力学性质的非线性,计算了光强为高斯分布的激光光束加热钢板时的温度场和热应力场,得到了温度场和热应力场的分布及其随时间的变化规律.通过对结果的分析,认为在激光作用前期热膨胀会造成热应力上升,而后期材料的热软化会导致塑性区域应力水平下降和其他区域应力水平增加缓慢甚至下降.有限元计算结果与已知实验结果的对比表明了有限元法的有效性.

Temperature and thermal stress fields during the laser irradiating a metal plate

Based on Von Mises yield criterion and elasto-plastic constitutive equations,an axisymmetric finite element model of a Gaussian laser beam irradiating a metal substrate was established.Taking nonlinear thermal and mechanical properties into account,temperature and stress fields generated by the laser beam in a steel plate were computed by the model.And distributions and histories of temperature and stress fields were obtained.By the analysis of the results,it is found that thermal expansion leads to the increase of stress level early during the laser irradiating,and thermal softening causes the decrease of stress levels in the plastic zone and the slow growth and even the decrease of stress levels in other zone later.Comparison of the numerical results with the reported experiments results shows the availability of the finite element method.