摘要
A nonlinear acoustic technique for detection of contact defects in plates was devel- oped associating guided waves with vibro-modulation techniques. The low frequency vibration varies the interface area within the contact defect; then the amplitude and phase of high fre- quency guided waves reflected from the contact defect will be modulated. Due to the exiting of contact defects, there was obvious low frequency component in the time-frequency distribution of modulated guided wave series. Furthermore the nonlinear responses at frequency of vibra- tion were extracted out and used for defect imaging. It was shown that the nonlinear guided wave imaging method based on vibration modulation can effectively characterize and locate the nonlinear contact defects.
A nonlinear acoustic technique for detection of contact defects in plates was devel- oped associating guided waves with vibro-modulation techniques. The low frequency vibration varies the interface area within the contact defect; then the amplitude and phase of high fre- quency guided waves reflected from the contact defect will be modulated. Due to the exiting of contact defects, there was obvious low frequency component in the time-frequency distribution of modulated guided wave series. Furthermore the nonlinear responses at frequency of vibra- tion were extracted out and used for defect imaging. It was shown that the nonlinear guided wave imaging method based on vibration modulation can effectively characterize and locate the nonlinear contact defects.
基金
support by the National Natural Science Foundation of China(10772008,51075012)
Beijing Municipal Science & Technology Commission(2007B012)
Beijing Municipal Commission of Education (KM200810005009,KZ200810005001)
