Crush bead design method and crush bead design device excellent in crushing collision mode control

摘要

PROBLEM TO BE SOLVED: To provide a collapsible bead design method and a collapsible bead design device excellent in dimensional accuracy at a timing of pressing and in controlling a bending position and a bending direction during axial collapse deformation in relation to a vehicle body skeleton component on which an axial compression load for which a frame longitudinal direction matches a collision direction acts.SOLUTION: Two reference cross-sections orthogonal to a ridgeline direction are selected for three-dimensional data on a frame component. A plurality of cross-sections parallel to the reference cross-sections are formed in a region between these reference cross-sections, and a cross-sectional line length of each of the formed cross-sections is calculated. Further, a longitudinal distribution of the cross-sectional line length is calculated in a region surrounding a bead portion, and an excessive thickness rate (=A/l) representing a risk of wrinkle overlap is calculated from a longitudinal integral value A of a line length difference and a bead width I. It is determined whether the wrinkle overlap occurs on the basis of a table of limit excessive thickness rates each of which is preset for a plate thickness of the frame and a material strength and at which no wrinkle overlap is generated and the excessive thickness rate .