荆条胶接接头的力学性能研究
Research on Bonding Joint Mechanical Properties of Vitex negundo Twigs

为通过胶接加长技术研发荆编家具提供理论依据，选直径相近的荆条试样制成不同接头形式测试其胶合性能。胶接接头的拉伸试验结果表明：搭接接头、交错对接接头、嵌接接头、斜接接头承受的最大拉伸载荷为1.226 KN、1.30 KN、1.422 KN、1.568 KN，破坏应力主要为胶合切应力，因此拉伸胶合强度基本相同。胶接接头的扭转试验结果表明：嵌接、交错对接、斜接三种接头的扭转强度相近，切变模量相近；与无接头试样比较，扭转强度明显降低，但切变模量基本相同。胶接接头的弯曲试验结果表明：方向一(沿试样长度方向的胶接面放置成水平面或与水平方向成倾斜面)加载，破坏应力均为弯曲正应力，斜接、嵌接、交错对接接头的弯曲胶合正应力分别为72.77 MPa、52.97 MPa、38.97 Mpa，弹性模量分别为20.14 GPa、7.99 GPa、5.61 GPa；方向二(沿试样长度方向的胶接面放置成铅直面或与铅直方向成倾斜面)加载，破坏应力均为弯曲切应力，斜接、嵌接、交错对接三种接头的弯曲胶合切应力分别为6.31 MPa、3.56 MPa、1.72 Mpa，弹性模量分别为13.53 GPa、11.26 GPa、8.45 GPa。而无接头试样的抗弯强度是正应力169.41 MPa，弹性模量为14.51 GPa，与斜接接头的弹性模量没有明显差异。综合接头拉伸、扭转、弯曲时的胶合性能得知，斜接接头为首选胶合接头形式。
In order to provide a theoretical basis on Vitex negundo twigs furniture by gluing lengthened tech-niques, the author used similar diameter Vitex negundo twigs to make different joints and tested the gluability of the joints. The results of the tensile tests showed that the maximum tensile loads of lap joint, staggered butt joint, rabbet joint and scarf joint were 1.226 KN, 1.30 KN, 1.422 KN and 1.568 KN in turn, and the breaking stress was glueing shear stress, so the tensile strengths of these four joints were on the whole the same. The results of the torsion tests showed that: the torsional strengths and the shearing modulus of rabbet joints, staggered butt joints and scarf joints were close; the torsional strengths of jointed test specimens decreased obviously than jointless speci-mens, but the shearing modulus was almost the same. The results of bending tests showed that the breaking stresses were bending normal stress loaded in direction one (the cemented surfaces in the length direction of the sample were placed in horizontal plane or inclined to the horizontal direction), the values of the bending normal stress of scarf joint, rabbet joint and staggered butt joint were 72.77 MPa, 52.97 MPa and 38.97 MPa respectively, the modulus of elasticity were 20.14 Gpa, 7.99 Gpa, 5.61GPa in turn; loaded in direction two (the cemented surfaces in the length direc-tion of the sample were placed in vertical plane or inclined to the vertical direction), the breaking stresses were all bending shear stress, the values of the bending shear stress of scarf joint, rabbet joint and staggered butt joint were 6.31 MPa, 3.56 MPa and 1.72 MPa respectively, the modulus of elasticity were 13.53 Gpa, 11.26 Gpa, 8.45 GPa in turn. The bending strength of jointless test specimen was 169.41 MPa normal stress, the modulus of elasticity of jointless specimen was 14.51 GPa. By analyzing the bonding performance of different joints in tensile, torsional and bending tests, we concluded