変位場計測に基づく有限要素法による超高張力鋼板の局所破壊ひずみと延性破壊限界の同定

抄録

In the present work, we combined a measuring method, the digital image grid method (DIGM), with the finite-element method (FEM) to analyze local strains, local stresses and the damage limit. We called the method displacement-measurement-based FEM (M-FEM). Transient displacement fields during a uniaxial tensile test were directly measured by DIGM. With the aid of M-FEM, detailed distributions of local strains and local stresses in large deformation zones were investigated. Then, the change in the local anisotropic parameter of high-strength steel sheets with plastic strain from uniform deformation to fracture was evaluated. Furthermore, the local fracture strain and damage limit of several advanced high strength steel sheets (980MPa with t1.2mm, 980MPa with t1.6mm, 1180MPa with t1.6mm) were identified by uniaxial tensile tests and M-FEM. The identified damage limit of materials agreed very well with that measured by a conventional press test. This verified the validity of M-FEM.