ボルト締結摩擦継手の負荷容量に関する考察

抄録

For the simple friction grip joint consists of two joined parts, one of which is tapped and bolted with the other with a bolt, the load capacity (Here, this is expressed by n described below) of the friction grip joint is analyzed using the strength of materials, and FEM analysis is carried out on 10 cases, which result in the following conclusions. [Here, F:Bolt axial tension, μ_CS : Friction coefficient on the contact surfaces between joined parts and also on the bolt bearing surface, W_SCr : Critical applied shear force without any slip, n : Equivalent number of contact surface (=W_SCr /Fμ_CS).] (1) Introducing the shear spring constant of the bolt K_BS and that of the joined part K_CS, the theoretical equation to calculate the load capacity n, which contains only K_BS and K_CS, is derived. (2) The load capacity n_th, calculated by the theoretical equation substituting K_BS and K_CS obtained through FEM analysis, coincides very well with n_FEM obtained through FEM analysis. Therefore, it is concluded that the theoretical equation to calculate n using K_BS and K_CS is correct. (3)According to this theoretical equation, to increase the load capacity n, it is necessary to develop the joint structure which gives smaller K_CS/K_BS. (4) The maximum load capacity n=2 is obtained only under K_CS=K_BS in the case of the concentrated shear load applied on the upper corner of the joined part. (5) The problem left to predict n is to derive the equation that can accurately calculate K_CS. (6) From the results of this analysis, the number “q _F”, which is described in VDI 2230 Part 2 and corresponds to n, is judged to be too large from the viewpoint of slip.