基于模态试验的对接圆柱壳结构有限元模型修正

Finite element model updating of butted cylindrical shell structure based on modal tests

壳体组合结构广泛应用于船舶、土木和航空航天等工程领域。为获得精确的对接圆柱壳结构动力学模型,采用基于数学模型的响应面法对有限元模型多个参数进行优化,实现有限元模型修正。通过模态试验获得对接圆柱壳结构的试验模态参数,采用模态置信度检验模态试验结果。利用ANSYS有限元软件对结构进行有限元模态分析,提取整体模态。通过中心复合设计方法获取样本点构造多项式响应面模型,采用决定系数和均方根误差检验响应面的拟合精度。响应面模型计算结果与试验结果的误差构造目标函数,多目标遗传算法用于优化响应面参数,最终将修正后的参数代入有限元模型得到修正模型。对比修正前后的模态频率,结果表明修正后得到的有限元模态频率与实测模态频率间相对误差明显减小,进而验证了基于响应面方法在对接圆柱壳有限元模型修正中的有效性。

Shell composite structures are widely used in marine,civil,aerospace and other engineering fields.Here,to obtain accurate dynamic model of butted cylindrical shell structure,the response surface method based on mathematical model was used to optimize several parameters of its finite element(FE)model,and realize FE model updating.Test modal parameters of butted cylindrical shell structure were obtained with modal tests,and modal test results were verified using the modal assurance criterion.The FE software ANSYS was used to perform FE modal analysis and extract global modes.The polynomial response surface model was constructed by using the central composite design method to obtain sample points,and the fitting accuracy of the response surface model was examined by using coefficients of determination and root mean square error.The error between response surface model calculation results and test results was used to construct the objective function,and the multi-objective genetic algorithm was employed to optimize response surface parameters.Finally,modified parameters were brought into the FE model to obtain the modified FE model.Comparing modal frequencies before and after model updating,the results showed that relative errors between FE modal frequencies obtained after updating and measured modal frequencies are significantly reduced,which verifies the effectiveness of the method based on response surface in FE model updating of butted cylindrical shell structure.