Detection of bolt tightness degree based on HHT

To solve the problems of bolt tightness degree detection in large structures, this paper studies the bolt tightness degree detection method in aluminum plate structure, by using piezoelectric sensor array to stimulate Lamb wave and HHT method to pick-up damage diagnostic parameter. The theory of HHT method is introduced, as well as the constitutions of the experimental system. Deal the echo signal that is received by sensors with EMD (empirical mode decomposition) method. After that, we get the IMF(Intrinsic mode function)-C2, and we further handle C2 with HHT method. According to the HHT results, we extract out the damage eigenvalues - Energy Frequency Shifting Ratio (EFSR) and Damage Energy Estimate Ratio (DEER) to improve the recognition rate of bolt tightness degree detection. In the end, an experiment of bolt tightness degree detection is carried out. The results indicate that the detection technology about Bolt Tightness degree based on HHT is quite effective.