Influence of bolt preload degradation on nonlinear vibration responses of jointed structures

The clamping performance of bolted joints was gradually degrading under long-term vibration loads, which induced a great impact on the stick–slip friction contact behavior of bolted joint interfaces . In this paper, a time-varying Iwan model was developed to reproduce the tangential hysteresis behavior of bolted joint interfaces by considering preload degradation. A three-degree-of-freedom mass–spring-damper oscillator was numerically simulated to investigate the influence of preload degradation on nonlinear vibration responses, as well as the experimental investigations of a bolted joint structure. The comparison results showed that the proposed model could well describe the effects of preload degradation on the stick–slip friction contact behavior of bolted joint interfaces. The numerical results revealed the nonlinear effects of preload degradation on the frequency response functions (FRFs), which demonstrated good agreement with experimental results.