Inverse analysis of distribution of internal small defects

This paper deals with a method for predicting the three-dimensional distribution of internal defects from the two-dimensional observation of intercepted defects on an inspection plane, by inverse analysis. First, the fundamental relationships between the three-dimensional distribution and the two-dimensional observation of internal defects were analytically derived on the basis of a statistical model where multiple penny-shaped cracks in an infinite body were intercepted by an inspection plane. The validity of the method was confirmed by a numerical simulation. It was, moreover, applied to small creep-fatigue cracks distributed in a smooth specimen of Type 304 stainless steel, and the volumetric density and the distribution of crack size were successfully evaluated.