悬架迟滞非线性特性对汽车平顺性的影响

INFLUENCE OF HYSTERETIC NONLINEAR PROPERTY OF SUSPENSION ON AUTOMOBILE RIDE COMFORT

首先建立了悬架系统的数学模型。由于悬架系统中具有众多的橡胶减振元件,其应力—应变循环具有变刚度变阻尼的非光滑、强非线性特性,恢复力表现出与变形历史有关的迟滞性。为了建立其数学模型,论文将恢复力分解成非迟滞非线性弹性恢复力和纯迟滞非线性阻尼力两部分,并用多项式和类椭圆函数分别进行模拟,用所建模型重构恢复力—位移迟滞回线,与试验结果吻合较好。然后利用系统动力学和随机振动理论,将汽车简化为四自由度模型,建立考虑悬架迟滞非线性特性的整车系统在路面随机激励下的非线性动力学方程。最后用Monto Carlo法模拟路面随机激励谱,在时域内对整车非线性系统振动特性进行仿真,并与传统的考虑线性悬架系统的整车动力学特性进行对比,以研究悬架迟滞非线性特性对汽车平顺性的影响。

The mathematic model of suspension system was established.For there are many rubber components in suspension system,its stress-strain curve is of unsmoothed and strongly nonlinear properties,and the restoring force is of hysteretic characteristics related to distortion history.In order to establish its mathematical model,the restoring force was separated into two parts:elastic part and damping part,and different functions were used to simulate them.The force-to- displacement hysteretic loop was reconstructed using obtained model,which fits in with the experimental data.Then,in accordance with the theories of system dynamics and random vibration,4 DOFs nonlinear dynamic equation of the whole car under road random excitation and considering hysteretic nonlinear properties of suspension,was set up.Monto Carlo method was employed to simulate road exciting spectrum,and the kinematic differential equation of whole car system was simulated in time domain.The result of simulation was also compared with that of the corresponding linear system.The in- fluences of nonlinear suspension property on automobile ride comfort were illustrated.