| In 2021,the country started to implement the construction project of forest ecolabeled products([2021]No.4 Document of State Council).Solid wood furniture needs to use adhesives when connecting the components,which brings high strength connection and generates many organic volatile compounds(VOC),which is harmful to people’s health.Therefore,this paper proposes a glue-free jointing method based on the principle of dry shrinkage and wet rise of wood,in which the split elliptical tenons dried to an absolutely dry state are matched with mortise and tenon eyes,and then the pre-stress is generated by moisture absorption and swelling to achieve a high-strength connection.In this paper,we studied the material-related properties,determined the preparation process and better process parameters of split elliptical tenon glueless nodes,studied the influence of tenon texture,tenon thickness,member material and member texture on the nodes’pullout and bending resistance,and established the nodes’ pullout and bending resistance load-bearing capacity models,and the research results provided the theoretical basis for the optimal design of split elliptical tenon nodes of solid wood furniture.The main conclusions are as follows:(1)The relaxation coefficient and friction coefficient are negatively correlated with the wood density,and the relaxation behavior decreases from chord to radial direction;the local compressive strength is positively correlated with the wood density,and the local compressive strength increases from chord to radial direction.The tenon can be prepared as a split elliptical tenon with no glue node by regeneration treatment;0.3mm overfill in the width direction and 0.1mm gap in the thickness direction are the better fit parameters,and the pullout resistance reaches 85.9%of the limit value after 48H regeneration treatment,which is suitable for production practice,and close to the limit performance after 96H,which is suitable for experimental research.(2)Pull-out resistance:one end of the vertical member is at the node failure,and it is in the elastic state when it fails,and the plane friction is superimposed on the surface friction.The material elastic modulus,contact area,actual fit value and intermaterial friction coefficient are the key parameters affecting the pullout resistance.The radial tenon,12 mm thick tenon,catalpa member and radial member could obtain better pullout resistance due to larger plane friction,curved contact area and material elastic modulus,respectively.The ultimate pullout resistance of the control group without gluing node specimen is 1836.6N,which is about 47.6%of the gluing process specimen and 329.4%of the blank treatment specimen,and the drying treatment can improve the pullout resistance of the node.(3)Bending bearing performance:the shear support reaction point is located at the end of the vertical member,the end of the horizontal member meets the pure bending condition,the node fails in the mortise of the upper end of the horizontal member after two elastic stages and plastic damage stage,considering the mechanical model established by the pressure moment and friction moment,the error between the calculated value and the test value is kept within 22%,the local compressive strength of material,contact area,initial contact force and friction coefficient between materials are the key parameters of the model.The radial tenon,12 mm thick tenon,catalpa member and radial member can obtain better flexural performance due to the larger plane friction,surface contact area and local compressive strength of material,respectively.The damage load of the control group without gluing node specimen was 1323.7N,and the damage bending moment was about 89.1N·M which was close to that of the gluing process specimen,and the two elastic loads and damage loads of the glueless node specimen were higher than those of the blank treatment specimen by 135.4%,66.3%and 40%,respectively,and the drying treatment could improve the flexural load bearing performance of the node. |
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