Optimal design of welded structure with structural and local-notch stresses based on International Institute of Welding recommendations

Abstract

A procedure for optimally designing light-weight and reliable welded structures is proposed and applied to the structural design of an illustrative welded structure used in construction and transportation machinery. To verify the effectiveness of the design procedure, the designed structures were experimentally produced, and then the fatigue lives of them were evaluated. The proposed design procedure is composed of two major processes; one is thickness-design process, and the other one is the process for designing weld type. Since the design for thickness and weld type is conducted sequentially, the thickness of welded structures can be determined in an optimization process without considering weld type; hence, the proposed design procedure is not computational demanding. In the thickness-design process, the thickness of a target welded structure is optimized by constraining structural stress that is estimated on the basis of the International Institute of Welding recommendations. After the thickness optimization, weld type of welded joints is designed by using local-notch stress, which is also defined in the IIW recommendations. Two kinds of test pieces based on the designed welded structure were experimentally produced by changing the weld type of a joint, and the test pieces were fatigue tested to verify their fatigue resistance. Since the produced welded structures had expected fatigue resistance, it can be concluded that welded structures can be optimally designed by using the proposed design procedure.