激光冲击低碳钢箔的有限元分析

Finite element analysis for laser peen forming of low carbon steel foil

激光微冲击成形是利用脉冲激光产生的等离子体爆轰波的冲击力效应,使超薄板材产生塑性变形的新技术。为揭示板材参数、激光参数、微凹模直径等对成形过程的影响,利用动态显式有限元法,对低碳钢箔的激光微冲击成形进行了反映率效应和尺度效应的晶粒级有限元模拟,结果表明,晶界对激光微冲击成形的影响很大,薄板的下凹变形随晶界厚度的减小而增大,二者呈近似线性关系;板材晶粒越不规则,其变形量越大;激光冲击的峰值压力是箔材变形的主要因素,随峰值压力的提高,变形量增大;单点多次冲击时,首次冲击的变形量最大,以后各次冲击的变形量逐渐减小。

Micro laser peen forming （μLPF） is a non-thermal laser forming method by using the short, intense shock wave induced by laser irradiation to shape the micro parts. To unveil the effect of the plate parameters, the laser parameters and the diameter of the micro die and so on, the dynamic explicit finite element method are employed to simulate the process of micro laser peen forming of low-carbon steel foil at a grain-level, considering the strain rate effect and size effect. The results show that： the grain boundary is significant in the micro laser peen forming. The concave deformation of the sheet increases as the thickness of the grain boundary decreases and it is nearly linear relationship between the two. The more irregular the grain, the greater the deformation is. The peak value of the shock force is the key factor in the micro laser peen forming. The deformation increases as the peak force increases. When several pulses are applied at one point, the deformation is the biggest at the first time and then gradually becomes smaller.