Nonlinear dynamic characterisation of jointed structures through response-controlled simulation and experimentation

The dynamic characteristics of jointed structures are often predicted using linear methods. However, at high excitation levels, nonlinear effects become significant, making these linear assumptions invalid and the prediction more challenging. Stepped sine excitation is a reliable approach for detecting such nonlinearities, typically performed using the Force-Controlled Technique (FCT). Despite its effectiveness, FCT requires long data acquisition and computation time in both experiments and simulations, limiting its practicality for nonlinear analysis. In this study, a new methodology for investigating nonlinearity in jointed structures using the Response-Controlled Technique (RCT) is proposed. The methodology starts by performing the Swept Sine Testing (SST) technique with a large force. The relative acceleration response between two points in the region of the bolts is calculated and a cubic stiffness is estimated using the Acceleration Surface Method (ASM). FCT and RCT tests are then performed at various excitation levels. The Nonlinear Frequency Response Functions (NLFRFs) and the time required to perform the nonlinear tests are measured.