超声检测识别CFRP复合材料PTFE夹杂与富树脂缺陷

Identification of PTFE Inclusion and Rich Resin Defects in CFRP Composites by Ultrasonic Testing

针对碳纤维增强复合材料(Carbon fiber reinforced polymer,CFRP)缺陷试样制作困难且不同夹杂缺陷难识别的问题,采用仿真与试验相结合的方法,开展聚四氟乙烯(PTFE)夹杂与富树脂缺陷超声检测研究。首先建立考虑CFRP层结构弹性各向异性的多向层合板超声反射法有限元模型,对比模拟与试验得到的A扫描时域信号,证明了模型的有效性。在CFRP层合板内部设置宽度6 mm,厚度0.03~0.40 mm的PTFE夹杂和厚度0.03~0.85 mm的富树脂缺陷,模拟得到超声A扫描信号,分析比较两种缺陷厚度变化对超声信号幅值最大值和波形峭度因子的影响。结果显示,随着缺陷厚度增加,PTFE夹杂及富树脂缺陷信号的幅值最大值和峭度因子均呈现先上升后下降最后趋于稳定的趋势,但富树脂缺陷信号幅值最大值低于PTFE夹杂,其峭度因子随厚度变化滞后于PTFE夹杂。

The fabrication and identification of different inclusions are difficult in carbon fiber reinforced polymer(CFRP)laminates.In this paper,ultrasonic testing of inclusions,including artificial delaminations with Polytetrafluoroethylene(PTFE)and rich resin regions are studied by numerical simulation and experiment.Firstly,an ultrasonic reflection finite element model of multidirectional laminate considering elastic anisotropy of CFRP layers is established,and the time-domain signals of A-scan obtained by simulation and experiment are compared to prove the validity of the model.Then,PTFE inclusion with a width of 6 mm and thicknesses of 0.03–0.40 mm and rich resin defects with thickness of 0.03–0.85 mm are preset inside the CFRP laminate.The ultrasonic A-scan time-domain waveform of the defects is obtained by simulation,and the influences of the two kinds of defects thickness changes on the maximum amplitude and the kurtosis factor of ultrasonic signals are analyzed and compared.The results show that with increasing defect thickness,the maximum amplitude and kurtosis factor of defect signals both show a trend of first increasing,then decreasing and finally stabilizing.However,the maximum amplitude of rich resin defects is lower than that of PTFE inclusion,and the variation trend of rich resin defects kurtosis factor with thickness lags behind that of PTFE inclusion.