Numerical and theoretical analysis of the contact force of oval mortise and tenon joints concerning outdoor wooden furniture structure

The contact force of oval mortise and tenon joints was investigated to get an in-depth understanding of the mechanical mechanism concerning outdoor wooden furniture structure. Experimentally, the contact force under different moisture content (13.50 and 50.00%), interference fit (0.1, 0.2, 0.3 and 0.4 mm) and grain direction (radial and tangential) was studied. A numerical simulation was conducted to examine the stress distribution and feasibility of the finite element method. The theoretical model was proposed for a deep insight into the contact force considering elastic constants, interference fit and geometric parameters of the oval tenon. According to the results, the moisture content and grain direction had significant effects on contact force, while the effect of interference fit depended on the moisture content. The result obtained by FEM was consistent with that of the experiment. The theoretical model can predict the contact force. The phenomenon that stress distribution in the thickness direction of the tenon shows a gradual increase from the sides to the middle part was evidenced both by FEM and the theoretical model. Response surface of contact force on tenon’s geometric parameters was also gained. This study is beneficial to outdoor furniture structure optimization.