考虑结合部特征的?150 mm口径反射镜模型修正

Model updating of a ?150 mm mirror including joint parts

针对150mm口径反射镜受结合部的非线性因素影响导致结构分析模型精度较差的问题,提出了线性的动力学等效建模与参数修正方法。首先,在实际装配和约束环境下测试并获得了反射镜结构的试验模态参数。然后,根据界面结合部的动力学特征,对反射镜结构按照镜框固定连接模型、镜面螺钉夹持模型以及间隙等效模型进行了等效建模。最后,以试验模态参数为修正目标,采用优化方法对反射镜结构的动力学等效模型进行了参数修正,并采用模型分层和分步修正的思路,依据结合部特征将修正模型细分为两部分,提高模型参数的修正效率。结果表明,参数修正后的固有频率平均误差为1.5%,模态置信度均大于0.8,提升了反射镜结构的动力学模型精度,验证了线性化等效建模方法的正确性。

For the problem of precision deficiency of the analysis model caused by nonlinear factors of the joint parts in the?150 mm mirror,the equivalent linearized model and the model updating method were presented.First,the experimental modal parameters of the?150 mm mirror within 800 Hz were tested and obtained under the actual assembly and boundary conditions.Then,according to the dynamic characteristics of the interface joints,the equivalent finite element model of the mirror was classified as the connection model of fixed parts,the screw model and the equivalent gap model of the clamping parts,which were modeled by beam elements,rigid elements and spring elements.Finally,taking the measured experimental data including natural frequencies and modal shapes as the objective function,the dynamic model of the?150 mm mirror was corrected by using optimization method.At the same time,the modified model was divided into two parts according to the characteristics of the joints by adopting the idea of hierarchical and step-by-step modification to improve the efficiency of the correction process.The results indicate that the average error of natural frequencies within 800 Hz after model updating is 1.6%,and the minimum value of modal assurance criterion is greater than 0.8,which improves the accuracy of the dynamic model for the reflective mirror.And the equivalent linearized model is also verified.