Development of Detection Method for Clamped Part Stiffness in Bolted Joint 2019-01-1113
If bolted joints are subjected to axial vibration, internal force which the bolts receive is determined based on the load factor that is a function expressed by the bolt stiffness and the clamped part stiffness. The stiffness of bolt and clamped part are calculated based on VDI2230 in general. Whereas we have to calculate the clamped part stiffness using FE analysis if configurations of the clamped parts are complicate or are made of multiple materials. FE analysis is very useful for calculations of the clamped part stiffness. However we cannot analyze all clamped parts and assess parts which have dimensional errors.
The new method which can detect the clamped part stiffness have been developed in this study. The proposed method is based on the clamp force detection method which we had proposed. In the proposed method, a protruding bolt thread portion is pulled supporting the nut upper surface at first while measuring a displacement at the pulling point. The gradient of pulling force in relation to the displacement changes when the pulling force reaches to the clamp force of bolted joint. In the clamp force detection method, we detect the pulling force, when the pulling force reached to the clamp force, as the clamp force. In the proposed method, we assess the clamped part stiffness using the gradient of the pulling force before and after the pulling force reaches to the clamp force. To verify the usefulness of the proposed method, we conducted the experiment to detect the clamped part stiffness. In the experiments, M10 hexagon head bolts and hexagon nuts were used, and cylinders made of stainless steel and pure titanium were assessed by the proposed method. The results showed that the proposed method can detect the clamped part stiffness with ±20 % accuracy.