Abstract
The spline shaft is used for an important part such as cars and machine tools. Therefore, the damage of the spline shaft causes a serious accident. On the other hand, the composite material is superior to the material which consists of a single material. An interface exists in compound material and stress concentrates in an interface. In this research, a spline shaft with two aspect is defined as "different aspects spline shaft". The model was produced by using epoxy resin. In order to reproduce the crack by metal fatigue, the crack was inserted in the crack progress direction. The intensity of the spline shaft was evaluated using the stress intensity factor. The stress intensity factor was measured using the hybrid method of photoelasticity method and method of caustics. The difference in the stress intensity factor by the difference in an inside diameter was examined.
