A brief introduction to the problem and importance of solid-solid contact as well as to the nature of surface topography is given. A number of experimental techniques, both direct and indirect, for determining the true area of contact between surfaces as well as a number of theories for predicting contact areas in the case of elastic, plastic, and elasto-plastic deformation of contacting surface asperities are reviewed. The effect of tangential loading upon the area of contact is also reviewed.

In order to implement a previously established goal of observing the nature of contact between transparent models of scaled-up surfaces, a procedure for three-dimensional model design, a technique for model fabrication, and an experimental apparatus have been developed. A computer program to predict points of contact and elastic contact parameters between macroscopic surface models is presented. Determining the range of application of the Hertz equations is discussed.

The computer program is used to predict the contact parameters between the three-dimensional surface models developed. For this situation the nature of contact was found to vary from the case of a single pair of asperities dominating elastic contact to the case of multiple asperity contact between several pairs of contacting asperities.