Identification Of Early-stage Damage In Boom Structure Of Construction Machinery By Wavelet Transform

The emergency and spread of the crack are latent threat to the security of the structure. Boom structure is a main component in kinds of construction machineries. The boom structure or even the whole machine will break down, the safety of the people will be affected once crack emergence in some import member structures of the boom structure.The aim of this publication is to detect the early-stage damage in the boom structure of crawler crane and tower crane on the background of the subject-350t crawler crane and K10000 tower crane which is developed by school of mechanical engineering of DUT and two corporations in Shandong province.(1)Compare the method of wavelet transform (WT) with other methods of crack identification and signal processing in order to present the main advantage of the WT in early-stage crack detection. Suitable wavelet function which is employed in the numerical examples in this paper is selected based on the fact that inertial moment in the section of crack is discontinuous caused by the crack.(2) 3D elements are adopted to simulate the simply supported and cantilever beams with damages. The paper employed dynamic and static analysis on beams to attain the response signals such as displacement, velocity and acceleration. Then use wavelet toolbox and wavelet function of MATLAB to pick out damage information.(3) Shell and beam elements are applied in the boom modal with damages. Signals of dynamic numerical experiments are analyzed by WT to study the location and severity of the damage.(4)The method of WT is also applied to the response signals with the disturbance of noise to detect the early-stage cracks.The results of the simulation make it clear that WT method is an appropriate way in detecting the location and degree of the early-stage damage in structures mentioned above. The method is also effective to the signal with noises.The results of the research show that WT is sensitive to structural local and early-stage damage. The WT is a robust and reliable way in early-stage crack detection in beam and truss structures.