Dynamic analysis of fixed-fixed beams

Abstract

Welded joints are often used to fabricate assembled structures in machine tools, automotive and many such industries requiring high damping and light weight. Many structures are made by connecting structural members through joints. Due to very low material damping of builtup
structures, sufficient damping has to come from the joints. Damping in built-up structures is often caused by energy dissipation due to micro-slip along frictional interfaces which provides a beneficial damping mechanism and plays an important role in the vibration behaviour of such structures. The damping characteristics in jointed structures are influenced by the intensity of pressure distribution, micro-slip and kinematic coefficient of friction at the interfaces and the effects of all these parameters on the mechanism of damping have been extensively studied. The ultimate goal of this project is to develop a damping model that is capable of describing the effects of welded joints on a vibrating structure. To estimate the damping capacity of a welded and layered fixed-fixed beam; it is investigated through analytically and experimentally. The theoretical analysis proposes two different methods to evaluate damping: classical and finite element method. In view of any discrepancy in results,
experiments are conducted for different sets of mild steel specimens under different vibrating conditions. Time domain approach has been adopted to evaluate experimentally the damping capacity of the fixed-fixed beams. Both the numerical and experimental results are compared for authentication. Finally, useful conclusions have been drawn from both the numerical and experimental results.