Abstract:Abstract:A new method for weld seam damage detection on steel tube welded structures based on model updating is proposed in this paper. The identified frequencies which are more accurate are selected as updating parameters, then the initial finite element model is updated by Ansys and Matlab based on sensitivity analysis. The objective function is defined as an nonlinear Ieast-squares problem with bound-constrains and for detection of the location of structural damage by minimizing the sum of differences between the experimental and analytical modal date, then the detection problem is transformed into an optimization problem in this method, and the trust-region approaching method is then used to solve the minimization problem. Finally, the proposed method is applied for damage detection on the frame of a launch platform. The elastic modulus reduction of jointing crunodes elements group is taken to simulate the weld seam damage state and two cases are investigated. The simulation and experimentation results show that the proposed method is well suitable for weld seam damage detection on such complex steel tube welded structures.