公开(公告)号：US20240027314A1

公开(公告)日：2024-01-25

申请号：US18265542

申请日：2021-08-12

Applicant: JFE STEEL CORPORATION

Inventor： Fumiaki TAMASHIRO ,  Akinobu ISHIWATARI

IPC: G01N3/06 ,  G01N3/20

CPC classification number: G01N3/06 ,  G01N3/20

Abstract: A method of calculating residual stress includes: measuring strain of a deformed portion of the metal sheet in a deformation process of plastically deforming the metal sheet and acquiring a strain history of the measured strain; calculating a stress increment of the deformed portion in the deformation process according to a material constitutive model using an acquired strain increment calculated from the acquired strain history and an assumed strain increment calculated, by assuming a deformation state of the deformed portion, from strain other than the strain from which the strain history is acquired, and sequentially updating stress from a start to an end of deformation of the deformed portion using the calculated stress increment; and determining, as residual stress of the deformed portion, the stress of the deformed portion at the end of the deformation in the deformation process among the sequentially updated stresses.

公开(公告)号：US20230152195A1

公开(公告)日：2023-05-18

申请号：US17916698

申请日：2020-12-01

Applicant: JFE STEEL CORPORATION

Inventor： Fumiaki TAMASHIRO ,  Satoshi SUMIKAWA ,  Masaki URABE

IPC: G01N3/08 ,  B21C51/00

CPC classification number: G01N3/08 ,  B21C51/00

Abstract: A method for identifying a necking limit strain of a metal sheet includes a step of measuring the distribution of strain in a tensile orthogonal direction in a tensile deformation process of a notch root for two or more types of sheet specimens having a notch geometry in a portion of a sheet edge; a step of obtaining a strain increment ratio of the notch root in the tensile deformation process and a strain gradient in the tensile orthogonal direction; a step of obtaining necking limit strain at which necking occurs in the notch root based on the strain increment ratio in the tensile deformation process; and a step of identifying the necking limit strain as a function of the strain gradient from the relation between the necking limit strain obtained for the two or more types of sheet specimens and the strain gradient at that time.