Development of a method for determining the contact spot of the shoe sole with the supporting surface

Relevance. As it is known, the parts that are between the foot and the supporting surface (e.g. ground, floor) – commonly referred to as shoe bottom – in the process of wearing shoes are subjected to the greatest impact. In conventional shoe constructions, the sole bears significant mechanical loads, including abrasion and cyclic bending. Prior studies of sole behavior during wear show that its destruction is associated with the value of specific pressures arising in the contact zone of the sole with the support. A critical consideration is that the contact between two bodies is always discrete, i. e. it occurs on separate spots of contact, whose size and number depend on the normal and tangential stresses, elastic properties of the contacted bodies and surface roughness. Determining the specific pressure in the outer layer of the shoe sole and the spot of contact is essential, as these parameters govern the intensity and wear mechanism. The aim of the research is to develop a methodology for determining the contact spot of the shoe sole with the support surface, to measure the area of actual contact, and to calculate the specific pressure in the contact zone of the sole with the support. As a result of the work, a technique for determining the actual spot of contact of a shoe sole with a support surface was developed; the area of actual contact was determined and specific pressure in the contact zone of the sole with a support was calculated. Analysis of the values revealed that with increasing load the area of the actual indentation increases and, accordingly, the ratio of the value of the area of the actual indentation to the nominal area. For the majority of specimens, it was found that with increasing load, the specific pressure in the contact area of the sole with the support increases, and the ratio of the actual contact area to the nominal touching area corresponds to the known values. The developed methodology and findings allow the prediction of the wear mechanism for the tested samples.