Non-homogenous localized Kelvin-Voigt model for estimation of dynamical behaviour of structures with bolted joints
Structures with contact interfaces show a non-linear behaviour with predominance of local energy dissipation in comparison to inherent material damping losses. This paper implements an equivalent local discrete spring-damper system at the contact interface based on generalized Hertz and Mindlin contact models for the definition of contact stiffness, with the motivation of capturing the major non-linear effects of predominant structural modes. In contrast to many time domain methods, the present model is implemented in the frequency domain to enable advantages of easy modelling and reduced computational time for various practical applications. A double layered beam with four bolted joints is used as base model for test and validation of the contact model. A pressure dependent joint model is illustrated in this paper to obtain the equivalent contact stiffness in normal and tangential directions. For excitations provoking tangential relative motion, the region of micro slip existing between the stick and sliding region is idealized for maximum damping. The structure's dynamic behaviour is quantitatively studied for a variation of bolt pretension (variation in contact pressure). A quantitative model verification and parameter study of the base model has been done with a set of experiments. Results have shown a good match for both eigenfrequency and modal damping between simulation and experiment. It can be concluded for the present contact model, that the model shows good convergence with experimental investigations and thus can be used for lightly damped non-linear systems at very efficient computational times.