The study on nonlinear dynamic behaviors of the structures with bolted-flange joint

Abstract

With multiple nonlinear behaviors involved, bolted-flange joints are complex in nature, especially when exposed to dynamic loads. In this paper, a simplified nonlinear dynamic model is proposed for a cylinder assembled by the bolted-flange joint. The geometric, material and contact nonlinearity is modeled by nonlinear spring elements with different tensile and compressive stiffness. The moduli of the springs are obtained from physical tests or numerical simulations. It is discovered that there exists a special type of conditional coupling behaviors between transverse and longitudinal vibration. To overcome the system energy dissipation, the implicit method in ANSYS and extremely small time step are employed. The data of displacement response, coupled with the response frequencies obtained thru FFT, validates the existence of the coupling vibration response.