Combing DGS and finite element for stress analysis using inverse boundary method

Digital gradient sensing (DGS) data combined with the finite-element method is proposed for stress solutions over the stress concentration area. Boundary conditions for a local finite element model, that is, the nodal force along the boundaries, are inversely determined from experimental values obtained by the DGS method. The DGS method measures the Cartesian stress gradient components directly. The sum in Cartesian stresses at all interesting points on the surface is obtained from the stress gradient using the linear least squares method. Thus, the sum stresses are used to compute the unknown boundary conditions for the local model. After boundary conditions are computed, the individual stress components are calculated by the direct finite element method. The effectiveness is demonstrated by applying the proposed method to a three-point bending specimen under the compression problem. Results show that the boundary conditions of the local finite element model can be determined from the DGS data and then the individual stresses can be obtained by the proposed method. (C) 2014 Optical Society of America