Theoretical analysis and model manufacturing of innovative mortise and tenon hollow spherical joint

One of the main challenges for free-form surface reticulated shell structure recently is the development of a new joint that is able to implement complex-shaped curvature and fulfill the required loading capacity, whilst also meeting various important requirements such as convenient on-site assembly and suitability for connecting members with various cross-sectional forms. This article draws inspiration from the construction idea of Chinese traditional mortise and tenon structure and proposes a new type of mortise and tenon hollow spherical joint. To investigate the joint’s mechanical performance, the detailed numerical models of 29 mortise and tenon hollow spherical joints with different size parameters are established by SolidWorks and Ansys, and the effects of the hollow spherical wall thickness, tooth width, tooth spacing, tooth height and tenon face width on the joint bearing performance are analyzed. The joint failure modes under bending limit states are discussed, and the calculation formulas for the initial and elastic-plastic stage rotational stiffness are derived. The results show that the joint initial rotational stiffness is increased by 34.45%, 4.69%, 4.29%, and 3.25%, respectively, after the parameter optimization analysis of the hollow spherical wall thickness, tooth width, tooth spacing and tenon face width. The mortise and tenon hollow spherical joint has good mechanical performance, and possesses the advantages of simple and beautiful appearance, fast construction speed and high positioning accuracy. Finally, a reduced-scale model of the mortise and tenon hollow spherical joint is manufactured using 3D printing technology to visually showcase its external feature and validate its assembly characteristic.