Experimental analysis of damping across joints in metal plates

Abstract

In the current world of engineering, structural vibration problems continue impact the design and construction of a wide range of products. Amid the parameters that determine the dynamic behaviour of a structure the one that takes into account the dissipation of energy resulting in the decay of the vibration is the least understood and the most difficult to quantify. The estimation of damping factors is of interest in most branches of engineering sciences. In the field of aircraft structures the damping directly affects the fatigue life, a parameter which is applied conservatively due to the inherent complexity in modelling the damping of built up structures and the potentially catastrophic consequences of a fatigue failure. One of the most important problems is the limited knowledge of how joints affect the damping of the complete structure. This work therefore addresses this issue and focuses on the damping of joints in metal plates as part of a larger project to investigate the damping of built up structures. Various plate configurations are experimentally investigated using two different approaches. The results from the configurations are compared and discussed along with the advantages and disadvantages of each experimental approach. This enables a link to be identified between the damping magnitudes and the mode shapes and joint stiffnesses