Experimental procedure for mapping Hertzian contacts

When ultrasound is incident at the interface between two rough surfaces som e of the wave is reflected. The proportion of the wave reflected is related to the level of conformity between the two surfaces. This principle is und er investigation as a method to determine the area of contact, and the load distribution, between contact elements in machine components. In this work the Hertzian contact between a ball and a flat surface has been scanned ul trasonically. The resulting reflection maps have been related to the local nominal contact pressure within the contact by a calibration procedure. The resolution of the measurement system is of the same order as the contact d imensions. To interpret the results both convolution and deconvolution nume rical procedures have been used. The resulting measured contact pressures a gree well with theoretical predicted Hertz pressure.