Studies On Damage Identification For Mechanical Structure Of Bridge Crane

With the development of industrial construction, bridge crane has been widely used in various fields in the national economic construction as an important material handling tool in modern production. However most bridge crane used currently was made in the 1980 s with long working hours and poor working conditions, due to the lack of mature injury determination, a lot of cranes were in a state of high-risk work for a long time, which caused a huge threat to the safe production of the enterprise. Therefore, how to accurately and effectively determine crane damage state is the key to guarantee safe operation and prevent major accidents. In this paper, we took bridge crane and its simplified structure of parts as the object, and did some research in the damage identification from two aspects including local damage location decision and overall damage judgment, and verified the feasibility of the method by experiment and simulation methods.The bridge crane metal frame's finite element model was built first, modal test and structural dynamics analysis was conducted on the bridge crane metal frame. After this, the equivalent model was updated in sensitivity analysis method by using modal identification data. Simulating structural damage with the young's modulus of a modified substructure and solving the corresponding residual stiffness values through the calculation of young's modulus variation of the structure so as to realize the damage of the structure as a whole. In addition, design simplified structural model of the crane and use a vibrator for white noise excitation and collecting the acceleration response signals before and after the looseness of the bolt model. Then, set up the response data of linear regression model through time series analysis and use the principal component analysis for the compression of high dimensional original data in order to improve the computational efficiency. Using Mahalanobis Distance to construct the damage factor based on time series model parameters so as to realize judging the local bolt looseness damage. Finally, in view of the local crack damage based on the crane girder, remove the cover plate alone for a cantilever beam structure,paste piezoelectric ceramic chip on the surface of the cantilever beam for high frequency of piezoelectric incentive, gather the acceleration response signal before and after crack damage. Using root means squares to construct the damage factor based on frequency response function so as to realize the qualitative judgment of the expansion the crack damage.