Modeling and sticking motion analysis of a vibro-impact system in linear ultrasonic motors

• A physical model is proposed to investigate the impact in linear ultrasonic motors.
• Vibration of barycenter of the stator is considered in modeling.
• Both mathematical model and simulation scheme are developed to study sticking motion.
• Some factors and parameters can affect sticking motion are investigated.

A vibro-impact system is proposed to investigate the normal motion and impact of the driving foot of the linear ultrasonic motors based on longitudinal and bending modes. Using coefficient of restitution (CoR) method a dynamical model is developed to simulate the normal impacts between the stator and mover taking into account the preload and vibration of barycenter of the stator. Furthermore, the sticking motions that can occur are simulated when the stator impacts the mover via a Lagrange multiplier. It is shown that the sticking motions occurring in the system are affected by some factors like CoR, preload and stiffness of the preload spring in clamping parts. Results indicate that a friction material with a higher hardness, modest preload and stiffness of the preload spring can weaken sticking motion in the system.