基于电磁超声的塑性损伤铝材抗拉强度预测

Prediction of tensile strength of plastic damaged aluminum based on electromagnetic ultrasound

针对电磁超声信号信噪比低这一问题,在利用相对非线性系数预测抗拉强度的同时引入应力三轴度来提升塑性损伤试件抗拉强度预测的准确性。建立了电磁超声非线性检测塑性损伤试件的有限元三维仿真模型,计算两个特征参量:应力三轴度和相对非线性系数,研究试件的内部应力状态特征和电磁超声检测信号的频谱特征。仿真分析结果表明这两个特征参量敏感的损伤阶段不同,应力三轴度对塑性损伤中后期较为敏感,而相对非线性系数对前期损伤较为敏感。建立了电磁超声非线性检测塑性损伤试件的实验平台,对不同塑性损伤试件进行电磁超声检测,测得其相对非线性系数;通过电子万能试验机测得抗拉强度,进一步对不同塑性损伤试件的相对非线性系数与抗拉强度的关系以及应力三轴度与抗拉强度的关系进行了量化分析,把两个特征参量结合进行抗拉强度的预测可以提高其预测的准确度。

Aiming at the problem of low signal-to-noise ratio of electromagnetic ultrasonic signals,the relative nonlinear coefficient is used to predict the tensile strength,and the stress triaxiality is introduced to improve the accuracy of the prediction.A three-dimensional finite element simulation model for the electromagnetic ultrasonic nonlinear detection of plastic damaged specimens is established.Two characteristic parameters:stress triaxiality and relative nonlinear coefficients are calculated.The simulation analysis results show that the sensitivities of the two characteristic parameters to different damage stages are different.The stress triaxiality is more sensitive to the late stages of plastic damage,while the relative nonlinear coefficient is more sensitive to the early damage.An experimental platform for electromagnetic ultrasonic non-linear detection of plastic damaged specimens is established,and the electromagnetic ultrasonic detection of different plastic damaged specimens is performed.The relation of tensile strength with relative nonlinear coefficient and the relation of tensile strength with stress triaxiality for different plastic damaged specimens are further quantified.According to the sensitivity of the characteristic parameters to damage,the combination of the two characteristic parameters can improve the prediction accuracy in predicting tensile strength.