ASME Div．２規格における疲労評価の概要

抄録

This article outlines the fatigue evaluation methods specified in ASME Boiler and Pressure Vessel Code，Section VIII，Division　２．Three assessment procedures have been available after the　２００７　rewrite of the Division　２，i．e．Fatigue evaluation methods by(ⅰ)　Elastic stress analysis and equivalent stresses，(ⅱ)　Elastic-plastic analysis and equivalent strains，and　(ⅲ)　Elastic analysis and structural stress．The methods　(ⅰ)and　(ⅱ)　are intended to be used with the traditional smooth bar design fatigue curve．The method　(ⅲ)　is totally different from the　(ⅰ)and　(ⅱ)　in the use of the structural stress acting as the membrane plus bending stress normal to the expected through-thickness crack plane and the weld joint fatigue master S-N curve newly developed．This article briefly explains the code provisions and the scopes of applications for three methods with the revision histories，respectively．In addition，figures of those design fatigue curves for some specific cases are shown and compared each other．Possible range for variations of the weld joint fatigue master curve depending on the design parameters is studied for the practical use．