考虑法向载荷变化的微滑摩擦系统振动分析

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

工程结构中,常采用干摩擦阻尼器来降低系统的动力响应幅值。振动环境中,连接界面间存在着复杂的接触和摩擦行为,这些行为具有跨尺度、迟滞非线性和切法向耦合等特点。建立了一种能同时考虑法向载荷变化和切向微滑摩擦行为的接触力学模型,推导了模型恢复力和相对位移间关系的表达式,利用不同模型间的比较验证了模型的有效性。将该模型应用于简化的摩擦阻尼器系统,求解了简谐激励下系统的迟滞回线、单位周期的能量耗散和频率响应曲线,并对不同模型的特性进行了比较分析。结果表明:是否考虑法向载荷变化对系统动力学响应预测有很大影响;考虑法向载荷变化的微滑摩擦模型能够更加完善、准确地模拟接触界面间的力学行为。

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.