基于Lamb波和Hilbert变换的复合材料T型加筋损伤监测

Damage monitoring of composite T-joint using Lamb wave and Hilbert transform

为了监测整体成型复合材料结构的损伤,提出了一种基于Lamb波和Hilbert变换的能量损伤指数。首先,通过应用Hilbert变换提取Lamb波信号的波形包络;然后选取具有最大峰值的波包,将此波包在结构出现损伤后的能量变化值与损伤前的能量之比作为损伤指示;该方法不需要选择特定的Lamb波模式,克服了Lamb波在复合材料结构中存在的频散、多模式及模式转换给信号分析带来的困难;最后在复合材料T型加筋的损伤演化试验中,对该能量损伤指数进行了应用验证研究。研究结果表明:该能量损伤指数可以用于复合材料T型加筋的损伤监测,当能量损伤指数(EDI)值达到0.62时,所研究的复合材料T型加筋确定有损伤产生。

In order to monitor the damage of integrated composite structures,an energy damage index method was proposed by using Lamb wave and Hilbert transform.First,the envelope of the time signal was picked up according to Hilbert transform of Lamb wave.Then the wavepacket which had the maximum amplitude was selected and the ratio of the wavepacket energy change for damage to the wavepacket energy of baseline was defined as damage index.This index method did not need to select the special Lamb wave mode and was helpful to overcome the problems of signal analysis with frequency dispersion,multi-mode and mode conversion of Lamb wave in composite structures.Finally this index method was tested by monitoring the damage evolvement of composite T-joint.The results show that this method can be applied to the damage monitoring of composite T-joint,when the energy damage index(EDI)value reaches to 0.62,the composite T-joint certainly has been damaged.