基于有限元的脉冲激光辐照材料温度场研究

在激光超声检测过程中,为了合理加载脉冲激光的能量,以便获得幅值较大的超声波信号,同时避免脉冲激光造成材料的损伤,需要对脉冲激光辐照材料的温升进行数值计算。依据有限元理论,建立脉冲激光辐照材料的有限元模型,结合导热微分方程,将脉冲激光以热流密度的形式加载于材料表面,分析材料表层受激光辐照时的温度场,讨论有限元热分析时网格尺寸的选取对分析结果的影响。给出了材料表层受脉冲激光辐照时温度场的计算方法和网格尺寸的选择依据,并利用温度场的理论解析结果和应力场分析结果分别验证了温度场有限元计算方法的正确性和有效性。

Study on temperature field of materials irradiated by pulse laser based on FEM

To load the laser energy reasonably and obtain ultrasonic signal of large amplitude without damaging material surface in the laser ultrasonic testing,it is necessary that temperature field of materials irradiated by pulse laser is numerically calculated. Firstly,theoretical model of laser irradiating material was established. Then,combined heat conduction differential equation with boundary condition,laser energy was loaded on material surface by the form of heat flux,and temperature field was calculated,and it was found that the results of finite element analysis are consistent with those of theoretical analysis. And then,the effect of the mesh size selection on the temperature analysis results was discussed. The calculation method of temperature field and the mesh size selection were given when material surface was irradiated by pulse laser. Finally,stress field analysis results verify the validity and effectiveness of temperature field calculation method.