基于超声导波的复合材料结构疲劳损伤监测实验研究

Experimental study on monitoring of fatigue damage for composites by using ultrasonic guided waves

为快速评估复合材料结构的疲劳损伤状况,采用超声导波和时-频分析相结合的方法,对疲劳状态下的复合材料结构进行在线连续监测。对玻璃纤维增强复合材料试件进行拉伸疲劳试验,使用激光引伸计获取试件纵向刚度的变化,探究试件内部疲劳损伤的累积情况。利用小波变换对由压电传感元件激励和接收的超声导波信号在时频域进行分析,提取与疲劳损伤有关的信号特征;最后,通过多元偏值分析引入马氏平方距离,融合多个信号特征,确定复合材料试件中疲劳损伤的存在性以及表征其演变过程。实验结果表明所提出方法在复合材料结构疲劳损伤连续监测方面的有效性。

To rapidly evaluate the fatigue damage of composite structures,an online damage detection method is presented for continuously monitoring of fatigue damage in composite structures by using ultrasonic guided waves and time-frequency analysis.Glass fiber reinforced polymer(GFRP)specimens are fatigued under tension-tension loads.A laser extensometer is used to obtain the degradation of longitudinal stiffness of the specimens under fatigue states to reflect the accumulation of internal fatigue damages.Wavelet transform is applied to the wave signals actuated and sensed by piezoelectric transducers in time-frequency domain to extract features related to fatigue damage.Finally,Mahalanobis squared distance(MSD)is introduced through multivariate outlier analysis to determine whether fatigue damage exists and characterize their evolution in the specimen by integrating multiple signal features.The experimental results have demonstrated the effectiveness of the guide waves-based method in continuously monitoring of fatigue damage for composites.