Estimation of contact pressure between mechanical parts focusing on instantaneous frequency of ultrasonic pulse

Abstract

It is essential for machinery to precisely measure the contact surface pressure between the parts in order to assure the quality and improve the performance. In this research, we propose the method for estimating the contact surface pressure by using ultrasonic pulse. The contact surface pressure affect the thickness of liquid interposed between the parts, such as lubricating oil. Our proposed method indirectly estimates the contact surface pressure via measuring the thickness of the liquid. We demonstrate the effective method for measuring the thickness even when the liquid is very thin, focusing on instantaneous frequency of received ultrasonic pulse. In this paper, we estimate the preload of the roller bearing as a concrete application example. In the experimental result, the instantaneous frequency of the received pulse varied according to the preload. In the numerical simulation, the received pulse varied almost as well as the experimental on the assumption that the preload affect the liquid thickness interposed between the parts. These results indicate that our proposed method can estimate the preload of the roller bearing through measurement of the liquid thickness, and can be applied for the evaluation of surface pressure of not only roller bearings also other machinery.