Session: 30-02 Damping evaluation and effect I

Paper Number: 82840

82840 - Influence of the Contact Interfaces on the Dynamics and Power Flow Behavior of the Bolted Structure 

Bolted joints are widely used for the assembly of mechanical components to provide continuity of the structure and transfer internal actions (i.e. forces and moments) from one member to another. The contact and the dry friction behaviors of the bolted interfaces have great influences on the dynamical performance, especially those with light-weight and heavy-load like aero-engine. On one hand, the stiffness of the structure will be influenced by the variation of the interfacial contact state, which may change the vibration frequency of the structure. What’s more, it has been proved that most of the structural damping comes from the bolted interfaces with dry friction instead of the material, which is the main factor affecting the vibration response, especially in structures made of metal.

In this paper, the frictional contact behaviors of bolted flanges are studied firstly, to identify different areas of the interface in sticking or slipping. The contact model with relative displacements and variable normal load is used to build the dynamical model of the structure with bolted interfaces, and the calculating method alternating time/frequency domain for the nonlinear response, as well as the degree of freedom reduction technology for the complex structural systems, are developed for the prediction of dynamic response. Based on this, influences on the dynamics of the interfaces in different contact states are deeply studied. Meanwhile, the vibration power flow method for the structural system with frictional interfaces is built, which is used to study the effect of energy dissipation at interfaces on the power flow behavior of the bolted structure.

Simulation results show that the resonance frequencies and vibration responses of the bolted structures are deeply influenced by the interfacial contact state. The stiffness loss at the bolted interfaces can be large when the clamping force is small, which reduces the resonance frequencies. The stiffness loss can be reduced by enlarging the normal clamping force, which will lead to larger resonance frequencies. Damping is induced at the slipping contact area surrounding the bolt, which affects the vibration response as the contact state change at different loading conditions. The transfer/distribution characteristics of vibration energy in the bolted structure are visualized by the developed power flow method, and the results clarify the energy dissipation at the bolted interfaces by comparison of structures with or without contact interfaces. The study deeply reveals the stiffness loss and energy dissipation at the bolted interfaces and carries out the influence on the dynamics as well, which can be the effective guidance in the design of bolted structures.

Presenting Author: Yongfeng Wang Beihang University

Presenting Author Biography: Yongfeng Wang is a postdoc of Beihang University, majoring in dynamic behavior and the vibration control methods of structures.

Authors:

Yongfeng Wang Beihang University
Jie Hong Beihang University
Yanhong Ma Beihang University
Giuseppe Battiato Politecnico di Torino
Christian Firrone Politecnico di Torino