Research on the Damage Identification of Weld Metal Cracking of Metal Structure Based on PVDF

摘要

A new detection method for measuring weld crack of crane's metal structure is developed. It works by combining polyvinylidene fluoride (PVDF) with curvature operational shapes (COS) algorithm. First, the theory of damage identification using the imaginary part of frequency response function was analyzed, and the extraction approach of COS was illuminated in detail. Then, the fitting method which is called gapped-smoothing method (GSM) was chosen to obtain the COS of healthy structure. Next, experiments were carried out on a steel plate with weld cracks based on PVDF. The experiment result expresses that the positions of cracks could be located precisely and the index is very sensitive to the different length of cracks. Therefore it can provide reliable information for positioning and quantitative analysis of the weld cracks.