Model Correlation to a Nonlinear Bolted Structure Using Quasi-Static Modal Analysis

Bolted joints are common in many engineering structures, yet they introduce complexity when the interest is predicting the dynamic response of a system. Under large load amplitudes, the joint contact interfaces will slip and cause the response to be nonlinear. A method proposed by Festjens et al., and later elaborated upon by the authors and dubbed Quasi-Static Modal Analysis (QSMA), has made it feasible to model the contact between structures in detail and thus predict the nonlinear dynamic behavior. Prior works have shown that this is feasible (Wall et al, Predicting S4 beam joint nonlinearity using quasi-static modal analysis. In: IMAC XXXVII; Jewell et al, J Sound Vib 479:115376, 2020, yet) no work has rigorously correlated such a finite element model with experimental measurements. This work takes a step in that direction by quantifying the effect of various features in the FEM to the amplitude dependent damping and natural frequency predicted by QSMA. Specifically, the effect of the friction coefficient and the curvature of the contact interface on the QSMA predictions is found and quantified. The results so far show that some of these effects could improve model agreement.