Fatigue life prediction method for thin-plate laser welded part

摘要

PROBLEM TO BE SOLVED: To provide a method of estimating fatigue life of a thin-plate laser welding unit, configured to estimate fatigue life of a laser welding unit in a vehicle body component, simply with high accuracy.SOLUTION: A method of estimating fatigue life of a thin-plate laser welding unit includes: a first step of representing stress with a function of fatigue life N, on the basis of fatigue life obtained by a fatigue test using a test piece where an opening stress component, an in-plane shear stress component, and an out-of-plane shear stress component are generated alone, and stress obtained by finite element analysis of an analytical model formed by simulating the fatigue test and modeling a laser-welding unit with a solid element and other portions with a shell element; a second step of performing the finite element analysis of the analytical model on a member to be estimated, to calculate three stress components generated in an outer edge of the laser welding unit of the member to be estimated; and a third step of determining fatigue life N so that the sum of a power of a value obtained by substituting the relation obtained in the first step into a dominator and the stress obtained in the second step into a numerator becomes 1.