New applications of the method of caustics

Abstract The method of caustics is a very powerful technique for measuring the value of the stress-intensity factor. This method, however, cannot be applied to the three-dimensional stress analysis technique of stress-freezing, and it is rather difficult to apply to materials which exhibit small deformations such as ceramics. In this paper, several new application techniques for caustics are shown. These new applications are: (i) the analysis of the individual values of the optical constants using a simple method based on the theory of caustics, (ii) the analysis of the reason why the caustic pattern cannot be obtained in the frozen-stress model in the immersion liquid by the conventional caustics technique using those optical constants, and the proposition of a new technique to apply the caustic method on such a frozen-stress model, (iii) the caustic coating technique, (iv) the multiplication technique of the caustic, and (v) some examples of the application of caustics to ceramics.