Application of Photoelasticity to the Measurement of Stress Distribution under Rigid Wheel (II)

Discussion on driving wheel with sinkage

Abstract

In this paper, the stress distribution under a rigid wheel with sinkage is discussed based on the results obtained by photoelastic experiment.
Three different shapes of photoelastic material under rigid wheel were prepared and vertical and tangential forces were acted on the rigid wheel, one was acted on the axle and another on the periphery of the rigid wheel.
Prior to the experiment, a theoretical consideration was introduced assuming a stress distribution pattern under rigid wheel consists of two zones.
From the results of photoelastic experiment it was found that the stress distribution under rigid wheel driven with some sinkage mostly consists of two zones compressing zone and bulldozing one. Compressing zone produces thrust force to the drive wheel, whilst bulldozing zone acts as resist to the travel of the wheel. The difference between the thrust force produced from the compressing zone under the driving wheel and the resisting force from the bulldozing zone may make the effective thrust force of drive wheel.
All unknown factors were determined based on the following procedure.
(1) stress distribution was drawn
(2) compressing and bulldozing zones were determined
(3) Summation of external forces, vertical and tangential forces were shared by the ratio of both areas
(4) the center of gravity of each zone was determined
(5) the magnitude of resultant of reaction forces derived from the both zones was obtained
(6) other unknown factors such as components of the resultant were determined by procedure (5)
The calculated results from the above procedure were well valid in comparison to the theoretical approach.