Modeling and simulation of behavior of threaded fasteners under dynamic loads

Abstract

Bolted joints have the advantage over the other connections such as welding and riveted joints of the ease of dismantling the connected components. This is why they are used in engineering applications such as automobile engineering and aerospace engineering. Machinery vibration problems, e.g. bolt loosening, may get more severe if the operational frequency of the systems matches with any of the natural frequencies of the system. Numerical analysis of the bolted joint test rig was done with defined constraints and parameter equation for finding the natural frequencies, harmonic amplitude, fatigue life cycle and fatigue damage. Numerical analysis is non linear and very complex for multibody system and multi degree of freedom systems. Such problems can be controlled by carrying out modal and harmonic analysis of the system with the help of design softwares. The test rig considered in this work is a multibody system (MBS) and includes eight components in it. Various components of the system have been modelled in the CAD environment. These components are then assembled to get the overall CAD model of the experimental bolted joint test rig. Firstly modelling of the test rig for was done by using Creo5.0. newlineModal analysis of flexible components of the system has been carried out by HYPERWORKS13.0 software. This is followed by modal and harmonic analysis of the Creo5.0 model of the experimental test rig. Modal analysis helps in identifying resonance regions, whereas harmonic analysis helps in getting peak amplitudes at the points of resonance in the system. Such primary analysis of system plays important role in studying loosening of bolted joints as well as in finding out fatigue strength of the dynamic systems. Then the fatigue analysis of the bolted joint in three different loading conditions shear, bending, axial done. Result shows that the fatigue life is maximum in bending load case when compared with the cases of shear and axial loading. The fatigue damage is localized in bending and axial loading test