Vibration reduction of a structure by design and control of a bolted joint

Control of vibration and noise can be considered as one of the most relevant technological challenges for the designer. In this paper we propose to control the normal force at a bolted joint part of a structure with the aim to reduce the vibration of this structure. In the first part, we study a 4 degrees of freedom model (dof), for which we show the interest of taking as a criterion for the reduction of vibration the maximum displacement in a given point of the structure. Then we propose two control laws for vibration reduction. The first control law takes the critical frequencies of the structure as input parameters and the second does not need any information about the displacement or the eigenfrequencies of the system. In the second part we present a finite element model of a 3D bolted joint taking into account two types of non-linearity (unilateral contact and friction model) in which we show the risk of loss of rigidity in the case of inadequate friction force. We present also a dedicated method to solve this non-linear problem. In the third part, we propose an alternative solution for reducing the vibration by designing a structure with an add-on bolted joint.