响应面法的杆式超声电机有限元模型修正

Finite element model updating of a rod-type ultrasonic motor based on response surface method

现有杆式超声电机的有限元模型大都采用连续复合材料的简化结构形式,忽略了实际超声电机各部件间的接触特性,导致计算结果与实验结果具有较大偏差。针对该问题,提出了一种采用响应面法的杆式超声电机有限元模型修正方法,来获得高精度的有限元模型。该方法考虑了超声电机螺栓预紧力及各部件接触界面的法向接触刚度和摩擦系数,筛选出显著影响电机工作模态的参数,建立响应面模型替代超声电机的有限元模型实现快速计算结构响应的目的,并以实验模态分析结果为目标对模型进行修正。修正结果表明,修正后的模型模态频率的平均误差由修正前的1.20%降到0.21%,模型精度得到明显改善,表明以响应面的有限元模型修正方法对杆式超声电机以及类似夹心式压电振子的设计具有应用价值。

The existing finite element model （FEM） of rod-type ultrasonic motor is usually simplified by means of continuous composite structure style and ignores the actual contact characteristics between the parts of ultrasonic motor, leading to a wide difference between the calculated values and experimental results. To solve the problem, a FEM updating method of rod-type ultrasonic motor is presented to obtain a high-accuracy FEM. By comparing with the experimental modal analysis results, this method takes into account the bolt pretension and the normal contact stiffness and friction coefficient of the contact surface of ultrasonic motor, and then the FEM is updated by the response surface method, which includes selecting the significant parameters of working mode of motor and building the response surface model to replace the FEM. And the result of updating shows that the average error of modal frequencies of updated model drops to 0.21% from 1.20%, and the accuracy of FEM is obviously improved, which indicates the FEM updating based on response surface method has an application value on the design for a rod-type ultrasonic motor, as well as the similar sandwich type piezoelectric.