基于模型修正的钢管焊接结构焊缝损伤识别

Damage detection for weld seam on steel tube welded structures based on model updating

提出一种基于模型修正的钢管焊接结构焊缝损伤识别方法。利用从发射台骨架试验模型获取的模态参数,选择识别结果中精度较好的模态频率作为模型修正的基准频率。通过对待修正参数的灵敏度分析,运用ANSYS和MATLAB软件对有限元模型进行了修正。以实测模态和计算模态之间的误差建立一个带约束边界非线性最小二乘目标函数,将损伤识别问题转化为优化问题,并采用信赖域方法求解该优化问题。以有限元模型焊接结点单元组弹性模量的降低模拟焊缝损伤,并假定了两种损伤工况,通过对发射台骨架模型的数值仿真及试验研究,结果表明所提出的损伤识别方法识别效果较为理想,为解决这种复杂焊接结构焊缝损伤识别问题提供了新的思路。

A method for weld seam damage detection on steel tube welded structures based on model updating was proposed.Among the modal frequencies identified in model test,the more accurate ones were selected as updating parameters,and the initial finite element model was updated based on sensitivity analysis by using software Ansys and Matlab.The sum of differences between the experimental and analytical modal data was taken as an objective function of a nonlinear Ieast-square problem with boundary-constraint and then the detection problem was transformed into an optimization problem.The trust-region approaching method was used to solve the minimization problem.The proposed method was applied in damage detection of the frame of a launch platform.The elastic modulus reduction of the jointing crunodes elements group was taken to simulate the weld seam damage state.Two damage cases were investigated.The simulation and experiment results show that the proposed method is well suitable for weld seam damage detection on such complex steel tube welded structures.