泡沫夹层结构的超声检测特征成像

Nonlinear Ultrasonic Detection of Foam Sandwich Structure Based on Feature Imaging

中文关键词:  碳纤维/聚甲基丙烯酰亚胺  泡沫夹层结构  时域信号  频域信号  特征成像

英文关键词:CFRP/PMI  foam sandwich structure  time domain signal  frequency domain signal  feature imaging

中文摘要:

      某型号直升机采用了碳纤维/聚甲基丙烯酰亚胺(CFRP/PMI)泡沫夹层结构制作旋翼，针对此结构内部存在分层、脱粘等缺陷识别困难的问题，通过预埋人工缺陷制作对比试块，从检测原理上分析了超声时域特征成像原理和频域特征成像原理，分别采用缺陷幅值、底波幅值、缺陷深度、频域幅值、频域相位5种特征成像效果进行了对比分析，寻找最优特征成像方法。结果表明：不管采用时域信号特征成像还是频域信号特征成像都能够清晰地发现CFRP中的分层缺陷。但是对于CFRP/PMI泡沫的脱粘缺陷，时域幅值特征成像效果优于深度特征成像；频域信号特征成像优于时域信号特征成像；相-频特征成像优于幅-频特征成像效果。

英文摘要:

      A certain type of helicopter uses carbon fiber reinforced polymer/plastic/polymethacrylimide (CFRP/PMI) foam sandwich structure to make rotor blades.In view of the difficulty of identifying defects such as delamination and debonding inside this structure,a comparison test block is fabricated by pre-embedding artificial defects.In order to find the optimal feature imaging method,the ultrasonic time-domain feature imaging principle and frequency-domain feature imaging principle are analyzed from the detection principle,and the five characteristic imaging effects that are defect amplitude,bottom wave amplitude,defect depth,frequency-domain amplitude and frequency-domain phase are compared and analyzed.It is found that the delamination defects in CFRP can be clearly found by using time domain signal feature imaging or frequency domain signal feature imaging.But for the CFRP/PMI foam debonding defect,the time domain amplitude characteristic imaging effect is better than the depth feature imaging,the frequency domain signal feature imaging is better than the time domain signal feature imaging,the phase frequency characteristic imaging is better than the amplitude frequency characteristic imaging effect.