PREDICTION OF CONTACT PARAMETERS USING ULTRASONIC METHOD

An attempt to apply ultrasonic methods to evaluate the real contact area and the contact stiffness is reported. The ultrasonic method of the study of contact presented is based on the measurements of the coefficient of transmission of the longitudinal ultrasonic waves normally incident at the contact interface. The tested contact was built from two nominally flat ground steel surfaces loaded up to a contact pressure 400 MPa. On the basis of the experimental results and the acoustic model of contact, the fraction of real contact area and the contact stiffness vs. contact pressure were found. To verify the ultrasonic results, these parameters were calculated for the tested contact using the theoretical models of contact of rough surfaces: i.e. the Greenwood-Williamson model, the White-house-Archard-Onions model and the Bush-Gibson-Thomas model. The experimental results appeared to exceed the theoretical ones both for the fraction of the real contact area (10%-100%) and for contact stiffness (40%-100%).