| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a deformation state evaluation method for determining whether or not a cold-forming square steel pipe having a small width-thickness ratio, in which breaking becomes the ultimate state thereof when being subjected to a bending force, reaches an ultimate deformation state. <P>SOLUTION: In a deformation state evaluation method for cold-forming square steel pipe, a stress-strain relation in each portion of the cold-forming square steel pipe on the occasion of a bending force applied thereon is obtained by an FEM (Finite Element Method) analysis. Then, while a portion in which a local strain advances most quickly is regarded as the highest-risk portion, it is determined that a point of time when an equivalent strain of the highest risk portion reaches a uniform elongation of a material is that of the ultimate deformation state. When the FEM analysis is performed, the stress-strain relation in a weld heat-affected zone of the cold-forming square steel pipe is decided by using the hardness test results of the weld heat-affected zone and the stress-strain relation in a base metal part. <P>COPYRIGHT: (C)2012,JPO&INPIT |
