弹性常数是描述金属箔材力学性能的重要参数。为了准确地测量出金属箔材的弹性常数,提出了一种基于激光超声技术的无损检测方法。首先,采用数值方法求解弹性模量计算的逆问题;然后,采用直接耦合的有限元方法,分别计算了脉冲激光在20 μm厚的镁锂合金、304不锈钢以及6061铝合金三种箔材上激励出的超声场,将模拟得到的兰姆波速度代入数值计算程序,得到了弹性模量及泊松比的计算值,并将该计算值与有限元模型设定值进行对比;最后,结合铝合金箔材的实验测量,验证了数值求解逆问题方法的有效性。结果表明:利用所提出的数值计算方法可精确地得到箔材的弹性模量及泊松比。所得结果为进一步使用弹性常数描述金属箔材的力学性能提供了参考。

Elastic constants are important parameters to describe the mechanical properties of metal foils. To accurately measure the elastic constants of metal foils, a nondestructive testing method is proposed based on laser ultrasonic technology. First, the inverse problem of elastic modulus calculation is solved numerically. Second, the ultrasonic fields excited by a pulse laser on 20 μm thick foils of Mg-Li alloy, 304 stainless steel and 6061 aluminum alloy are calculated by the direct coupling finite element method. The simulated Lamb wave speed is brought into the numerical calculation program to get the calculation values of elastic modulus and Poisson''s ratio which are subsequently compared with the model specifications. Finally, the effectiveness of the numerical method for inverse problems is verified by the experimental measurement of aluminum alloy foils. The results show that the elastic modulus and Poisson''s ratio of foils can be accurately obtained by the numerical method. These results provide a certain reference for evaluating the mechanical properties of metal foils through the measurement of elastic constants.