Crack detection with strain gages and the body force method

The development of a stress estimation method based on the concept of 'Pseudo-3-D problem'. According to this method, a surface of a notched region of 3-D stress field, is treated as a pseudo 3-D plate without thickness. The method is applied to detect a crack near a notch of 3-D structures. The results of elastic finite element method (FEM) analysis is used to bring correct boundary conditions in stress estimation on the effect of strain gage's noise. The maximum stress is not generated at the notch edge but at the crack tip in a notched plate with a crack. Antiplane bending occurs on the plane containing the hidden crack due to the nonconformity of the centers in the tension and the ligaments. It is found that the forces and the Poisson's effect generate secondary deformation of the arrow that causes secondary compressive stress.