基于模态参数验证的机床结构件优化设计

Optimization design to machine tool structures using experimental verification of modal parameters

基于有限元分析和试验测试相结合的方法,研究机床结构件优化设计.以某型号拉床结构3大件之一的床台为例,建立床台实际几何形状的有限元模型,分析床台在实际工况下的变形情况和模态参数.利用LMS SCADAS III-305振动测试设备和PolyMAX方法,得到床台在0~512 Hz频率下的自然频率、阻尼比和振型等实验模态参数.获得实验模态与分析模态振型向量的置信准则矩阵,表明有限元分析和实验结果具有较好的相关性.利用经过验证的有限元模型开展拓扑优化,根据优化结果进行床台结构的二次设计.结果表明,通过二次设计得到轻量化的床台结构,切削点处变形更小,第一阶固有频率更大,实现了更好的动态性能.

A hybrid approach combining experimental tests with finite element(FE)analysis for optimization of the machine tool structures was presented.A FE model of the table base with the real geometry was constructed by considering the table base of a vertical external broaching machine.The deformation and modal parameters were calculated in practical operating conditions.The experimental modal parameters including mode shapes,damping ratio and natural frequencies of the table base were examined in a frequency band of 0-512 Hz by using LMS SCADAS III-305 system and PolyMAX method.The modal assurance criterion(MAC)value was used to analyze the correlation between the FE and experimental mode shape.Results indicated a high correlation between the experimental and numerical results.A lightweight table base structure was redesigned with a better dynamic performance from the topology optimization result based on the already correlated FE model,due to lower displacement of broaching machine at force point and higher first order natural frequency.