JE-MAP法を用いたデジタル画像相関法によるき裂形状の同定

Abstract

We are developing a method that estimates cracks that are invisible from the surface based on the surface deformation measured by digital image correlation (DIC). An inverse problem is set up to estimate such invisible cracks from the surface deformation. Surface deformation, measured by the DIC method, contains noise. Inverse problems have an ill condition. The regularization method applied in this study is an extension of the JE-MAP method. The JE-MAP algorithm alternates between Maximum a Posteriori (MAP) estimation and the Grab-cut (GC) method to avoid ill-conditions. The physical constraints on displacement and the forces at the cracks and the crack perimeters (ligaments) are added to the MAP method. The displacement and load at the cracks and the ligaments have a cross-sparse relationship. The MAP method estimates the displacement or the load at the cracks and the ligaments. The estimated result varies greatly at the boundary between the cracks and the ligaments. This boundary is determined by the GC method based on the estimated result. In this study, we further amplified the changes in our estimates at the boundary between the cracks and the ligaments. The amplified results were input into the GC method to improve the boundary-determination accuracy. Our extension of the JE-MAP method was combined with DIC to estimate the cracks in invisible locations.