考虑边界条件不确定性的塔机有限元模型修正

Finite Element Model Updating of a Tower Crane Including Boundary Condition Uncertainty

由于在大型塔机的模型修正中为简化计算,往往忽略了边界条件的不确定性,导致修正结果精度不够或修正计算收敛困难,为此提出一种考虑边界条件不确定性的塔机有限元模型修正方法。首先,以某型塔机为研究对象,进行整机风致振动实测,获取结构的实测动态特性;其次,建立考虑边界条件不确定性的塔机有限元模型,基于二次响应面法对该有限元模型进行修正;最后,将模型修正前后的计算结果与实测值进行对比。结果表明,考虑边界条件的影响能有效提高修正的精度,对结构的边界条件进行修正后的有限元模型能复现实测频段内的模态,也能以一定精度预测实测频段外的模态,证实了所提出的考虑边界条件不确定性的修正方法的有效性。

A method is proposed to update the finite element model(FEM)of a tower crane considering the uncertainty of boundary conditions.For tower cranes,the actual dynamic characteristics of the structure are obtained by the vibration testing.First,the FEM of the tower crane considering the uncertainty of boundary conditions is modified.Then,the FEM is updated based on the quadratic response surface method.The non-updated and updated frequencies are compared to the measured frequencies,and the comparison results suggest that the accuracy of the updated results could be improved by considering the influence of boundary conditions.The FEM whose boundary conditions are updated can reproduce modes in the tested frequency range and can predict modes out of the band accurately.These conclusions further show that the method proposed in this paper is feasible and efficient.