コースティックス法による応力拡大係数K_Iの測定について

抄録

Basic theory for the determination of stress intensity factor K_I by using the transmitted and the reflected techniques of caustics is described. Fundamental experimental apparatus of this method is shown and moreover some technical points which should be taken into consideration in the experiment are shown. Not only the laser light but also the white light can be used as a light source in the experiment, but sufficiently small size of point light source should be employed for the case of white light. It is pointed out that there occurs the effect of the size r0 of initial curve on K_I and a larger value of r0 than a definite one should be employed. Finally, some examples of application of this technique on various problems at our laboratory are shown. Multiplication technique of the caustic image is illustrated. When this technique is applied to the stress-frozen model in photoelasticity, there appears very different caustic patterns from those of usual one. As an example of application on the dynamic fracture problem, analysis of fracture behavior of ceramic materials under dynamic loading at high temperatures is described.