Non-contact study of mechanical contact problem using TV-holographic interferometry

This paper presents the experimental non-contact study of mechanical contact problems using the technique of TV-holographic interferometry. The displacement fields were obtained by bringing steel spherical indenters into contact with an aluminium plate and a special loading fixture was designed to produce precise contact conditions. Contact stress distribution was then derived from the displacement measurements. These results showed that a large displacement gradient occurs at the centre of the contact area, indicating contact stress concentration in the vicinity of the initial point of contact. The experimental results were compared with those from Hertz's theory and elasto-plastic finite element analysis. The comparison showed close agreement among the respective methods except for a slight deviation which was attributed to the frictional effect in the contact between indenters and the plate and the elasto-plastic behaviour of the aluminium material subjected to the contact loading. This runs contrary to the assumptions of frictionless contact and linear elasticity theory stated in Hertz's theory. The comparison clearly demonstrate that TV-holography technique is an accurate and reliable method for non-contact studies of mechanical contact problems. Copyright (C) 1996 Elsevier Science Ltd.