The porosity of carbon fiber reinforced polymer（CFRP） workpiece is tested by ultrasonic in pulse-echo mode.When the ultrasonic frequency is close to the resonant frequency of the workpiece,the resonance will occur a...The porosity of carbon fiber reinforced polymer（CFRP） workpiece is tested by ultrasonic in pulse-echo mode.When the ultrasonic frequency is close to the resonant frequency of the workpiece,the resonance will occur along the thickness direction.If the CFRP workpiece contains voids,the resonant frequency will decrease.The result of ultrasonic testing experiment clearly draws the conclusion that the center frequency of the backscattered signal spectrum declines with increasing porosity.Based on the above theory and conclusion,the three-dimensional（3D） voids identification and location method is established.Firstly,the ultrasonic signals are collected and the center frequencies of the backscattered signal spectra are calculated.Then the C-scan of center frequency is generated to identify the voids.At last the B-scan of center frequency for the region containing voids is generated to determine the depth of the voids.The experimental results show that,by using this method,the voids in the CFRP workpiece can be identified and pinpointed.展开更多
基金Funded by the National Natural Science Foundation of China(No.51075358)Zhejiang Key Discipline of Instrument Science and Technology(No.JL130112)Zhejiang Natural Science Foundation(No.LQ12E05018)
文摘The porosity of carbon fiber reinforced polymer（CFRP） workpiece is tested by ultrasonic in pulse-echo mode.When the ultrasonic frequency is close to the resonant frequency of the workpiece,the resonance will occur along the thickness direction.If the CFRP workpiece contains voids,the resonant frequency will decrease.The result of ultrasonic testing experiment clearly draws the conclusion that the center frequency of the backscattered signal spectrum declines with increasing porosity.Based on the above theory and conclusion,the three-dimensional（3D） voids identification and location method is established.Firstly,the ultrasonic signals are collected and the center frequencies of the backscattered signal spectra are calculated.Then the C-scan of center frequency is generated to identify the voids.At last the B-scan of center frequency for the region containing voids is generated to determine the depth of the voids.The experimental results show that,by using this method,the voids in the CFRP workpiece can be identified and pinpointed.
