3次元FEMを用いたねじ締結体締付け時の力学挙動解析

抄録

In design of bolted joints, it is important to understand bolt axial tensions to avoid joint loosening. In recent years, FEM models with three dimensional threads have been applied to analyze mechanical characteristics of bolted joints. In this paper, tightening experiments, elastic FEM analyses and simplified calculations were conducted for bolted joints which consist of two hollow discs tightened by a hexagonal bolt with flange and a hexagonal nut with flange in order to obtain relationships among rotation angle θ [°], bolt axial tension F [kN] and tightening torque T [Nm]. As the results, it was shown that the relationships between the rotation angle θ [°] and bolt axial tension F [kN] obtained by FEM analyses with three dimensional thread have good agreement with the experimental results in a range of an initial tightening, which has non-linear relationship between the rotation angle θ [°] and bolt axial tension F [kN]. After tightening the nuts and bolts until rundown condition, the relationships become linear in both experiments and FEM analyses. However, the values of bolt axial tensions obtained by FEM analyses are a little higher than experimental ones at a same rotation angle. Also, stress distributions of the bolted joints are revealed.