Driving Contact Analysis Of Traveling Wave Rotating Ultrasonic Motor

Traveling wave rotating ultrasonic motor is a new type of motor which bases on the reverse piezoelectric effect of piezoelectric ceramics to produce traveling wave vibration on the contact surface of stator and drive the rotor to rotate by friction.The motor has the advantages of high torque density,no magnetic field interference,simple structure,flexible design and so on.It has a broad application prospect in the fields of medical treatment,aerospace,precision instruments,robots,etc.In this paper,according to the shortcomings of ultrasonic motor,the finite element method was used for studying and analyzing the contact model of the motor,the structure optimization of the stator and rotor,the contact state of contact surface and the movement form of the particles,etc.The details is as follows:First of all,the characteristics and application background of ultrasonic motor were introduced,and the current research status and shortcomings of ultrasonic motor were summarized.The main problems faced by ultrasonic motor were: serious local wear of contact surface;low energy conversion efficiency of motor.This paper analyzed the composition,structural characteristics and working principle of traveling wave rotating ultrasonic motor,and established the stator analysis model,and carried out modal analysis and harmonic response analysis.This paper analyzed and selected the natural frequency and vibration mode of the stator,and obtained the amplitude frequency characteristics of the stator.Secondly,according to the structural characteristics of the ultrasonic motor,the stator and rotor analysis model was established,and the four main parameters that affect the mechanical performance of the motor,namely,the thickness of the rotor web,the thickness of the stator web,the width and height of the flexible part,were constructed.The ANSYS finite element software was used for simulation analysis,and under the same boundary conditions,the contact stress and contact stress of the contact surface of the motor caused by the changes of the structural parameters were analyzed.The influence of sliding distance and contact clearance distance were analyzed and summarized.Thirdly,BP neural network and finite element analysis were used for realizing the optimization design of ultrasonic motor structure.According to the selection of sample data in orthogonal test,BP neural network analysis model was established,and the relationship between the structural parameters of stator and rotor and the optimal contact stress were fitted.The influence curve of structural parameters on contact stress was predicted,and the contact state of contact surface was improved.Furthermore,the influence of the thickness of the stator web on the particle amplitude of the contact surface of the stator teeth was analyzed,and the curve of the change of the thickness of the stator web on the vibration amplitude was obtained.Finally,according to the established analysis model of the ultrasonic motor,the dynamic analysis of the contact surface of the stator and rotor was carried out,and the movement curve of the rotor particle was obtained.The wear of the friction layer of the existing ultrasonic motor,the spatial distribution of the contact stress of the contact surface,the distribution of the contact force along the radial and circumferential directions were analyzed.The motion track of the contact surface particle between the stator and the friction layer along the radial and circumferential directions were also analyzed.The contact area can be divided into driving area and blocking area,and the distribution length of each contact area would change under different loads.Furthermore,a new type of friction layer with grooves was proposed.Compared with the load characteristics of the original type of friction layer motor,the mechanical properties had been significantly improved.