Formulation of stress concentration factor and shape optimization of gooseneck joint under uniaxial tensile load

If we use wood as a structural material, we can reduce carbon dioxide emissions. In Japan, houses have been made by wood traditionally and wood is used as a structural material such as pillar and beam. In order to use wood as a structural material, a joint is necessary. The shapes of these traditional joints are determined empirically and used without any analytical evaluation such as stress analysis. Therefore, stress analysis is necessary in order to use such joints efficiently. In this study, we make stress analysis of the gooseneck joint, which is one of the typical joints in Japan. The strain distributions of the joint are measured, and the stress distributions are obtained by digital image correlation method (DIC). We also simulate the gooseneck joint subjected to tensile load by using FEM. A male part and a female part are contacted in the joint region. Comparing FEM results to DIC results, the validities of both results are confirmed. Moreover, we propose the formulae to obtain the joint stress concentration factor by using the FEM results. The optimum shape, which gives the least maximum stress under uniaxial loading, is obtained by using the proposed formulae.