Vibration analysis for a micro-slip frictional system considering variable normal load

Dry friction damper is widely used to reduce dynamic response amplitudes of engineering structures. There exist complex contact and friction behaviors in vibration environment, they have features of multi-scale, hysteretic, nonlinear and tangential-normal coupled. Here, a new interface contact mechanical model considering tangential micro-slip friction and variable normal load simultaneously was proposed. The relationship between tangential restoring force and relative displacement was derived. The correctness and effectiveness of the proposed model were verified through comparing it with other models published. Furthermore, the proposed model was applied in a simplified friction damper system. Under simple harmonic excitations, the hysteresis curve, energy-dissipation per period and frequency response curve of the system were calculated. The characteristics of different models were analyzed comparatively. The results showed that if considering normal load variation has an important influence on the system dynamic response prediction; the proposed micro-slip frictional model considering variable normal load can be used to simulate contact interface mechanical behaviors more correctly and perfectly.