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|1. (WO2014208697) METHOD FOR DETERMINING BENDING FRACTURE IN METAL PLATE, PROGRAM, AND STORAGE MEDIUM|
|Applicants:||NIPPON STEEL & SUMITOMO METAL CORPORATION
|Title:||METHOD FOR DETERMINING BENDING FRACTURE IN METAL PLATE, PROGRAM, AND STORAGE MEDIUM|
A bending fracture limit stress σcr is calculated for each bending radius R at plate thickness center/initial plate thickness t0 of a metal plate. A fracture limit stress σ1_pl under plane strain deformation is calculated, as is a fracture limit line L1 in a uniform deformation state in a stress space for which a static strain rate is assumed from work hardening characteristics obtained from uniaxial tensile testing of the material constituting the metal plate. A determination is made of the ratio γ between the bending fracture critical stress σcr and the plane strain fracture limit stress σ1_pl in a uniform deformation state that corresponds to the R/t0 of a determination subject element in the metal plate. The ratio γ is multiplied by the stress component of the fracture limit line L1, whereby a fracture limit line L2 corresponding to R/t0 is calculated. The maximum principal stress σOBcr of the determination subject element is calculated from the maximum principal stress σOR of the determination subject element and the fracture limit line L2 corresponding to R/t0 in a stress mode. A risk ratio σOR/σOBcr, which is the risk ratio for tensile bending fracture, is calculated from the sizes of the stress σOR and the fracture limit stress σOBcr. Fracture is determined for the determination subject element on the basis of the risk ratio σOR/σOBcr.