Stiffness of Cord and Rubber Constructions

Abstract

Abstract When the function performed by pneumatic tires in guiding vehicles by development of cornering force was first studied many years ago, a number of attempts at analysis were based on the concept that cornering force was developed primarily because of cross-bias construction. None of these attempts provided either a satisfactory or fruitful basis of analysis. Later, adequate guiding properties developed by experimental spring wheel designs when rubber was in short supply (1940–45) indicated that the cross-bias construction was not essential for cornering forces. Designs involving flexible but edgewise rigid belts or tracks were very successful in this regard. Analysis of these structures turned attention to the elastic beam on elastic foundation concept of a tire, not only for radial load carrying capacity but also for lateral and cornering properties. However, consideration as to where in the shoulder region the casing was to be taken as part of the beam and where it was to be considered part of the foundation, proved to be a stumbling block when considering a conventional tire. Development of the tire with radial ply casing and a rigid breaker band resolved this point by providing a tire where the ambiguity did not exist. In subsequent investigations the ambiguity for the cross-bias tire was resolved with measurements by the same experimental procedures at corresponding points on the tread band and discussing the tire in terms of effective stiffnesses.