The Beam Crack Detection And Analysis Based On Equivalent Load Method

Beam is widely used in some important production and facilities such as large mechanical device and bridge construction. So the study of different kind of faults in beam, in order to ensure the reliable operation of the production and safety, and to ensure the healthy and stable development of the national economy and people’s property security, has the vital significance. Therefore, the fast and accurate identification of types, location and depth in beam crack and to do the early detection and treatment is very necessary.In the problem of the DOF matching based on equivalent load method, the paper introduce a new method to divide the matrix into different blocks according to DOF’s character, and discard some useless and less affect blocks to solve the corresponding of theory and experiment. In the modal modification method, the sensitivity and optimal method is combined, and sensitivity value determines the changes direction, so it solves the problem of low efficiency. As the same times the iterative optimization method ensures the reliability of the results.It introduced a fault simulation and diagnosis method about the open cracked beam. The fault diagnosis method based on equivalent external load is a new solution of the equipment fault diagnosis and makes full use of the advantage of the traditional fault diagnosis method based on signal analysis and the linear dynamic model of the research object. In the method, the actual equivalent external load (residual displacement) is calculated according to the monitored dynamics response and then is matched by an optimization algorithm in the theory fault space in order to identify the equipment fault quickly and accurately. The method verified by theory and experiment modified the crack’s location and depth, and proved the accuracy and reliability successfully.According to the simulation for the breathing crack, the paper considered the nonlinear effects of breathing and used cosine switch function to complete the fault diagnosis by calculating the equivalent load with the characteristics of time sequence of matrix. In this way, it simplified the complex nonlinear problem. At the same time, on two aspects of theory and experiment, it identified the position and depth of crack and verified the equivalent load method based on breathing crack fault in the practical.By analyzing in two aspects of experimental and theoretical, it verifies the effectiveness of fault diagnosis method based on equivalent load. it can not only identify the location of crack accurately, but also identify the depth of crack. It fully confirmed the validity, accuracy and stability of the method, and reveals its potential applications in related fields.