2017 Volume 24 Issue 95 Pages 95_69-95_78
Welded joints of modular type expansion devices are constructed with fully penetrated welds to prevent root fatigue failure at present. Here, the fully penetrated welds, which require a lot of time and cost, are revised to partially penetrated welds, and conditions to prevent the root failure are discussed. Specifically, fatigue tests and stress analyses on specimens simulating the welded joints have been performed, and their results suggest that the origin of fatigue failure can be distinguished by effective notch stress conception. In addition, the conditions for preventing the root fatigue failure are made clear through FE analyses on models with various weld leg length, weld penetration depth, and toe curvature radius.