Modal analysis of a single-lap joint under dynamic loading

A well-known source of energy dissipation of mechanical vibration in built-up structures is the frictional forces arising from the relative motion of two mating surfaces, internal material damping and induced pumping in air gaps. Dissipation of mechanical vibration energy at contact interfaces in built-up structures is commonly referred to as interface damping in the research literature. Out of all the energy dissipation methods mentioned earlier, the most significant and immensely powerful source of vibration damping in mechanical structures is the contact interface damping. Investigation of damping associated with bolted joints in dynamic built-up structures is presented in this paper. Bolted single-lap joints are chosen for performing experimental investigation and subjected to different dynamic loadings and tightening torques to study the effects these conditions have on interface damping. A wide range of bolt torques are considered for this investigation to analyse the impact of contact interface damping on built-up structures. Modal parameter extraction methods are used to estimate the damping in selected modes and compare the ability of the methods in estimating the loss factor.