铁道车辆二自由度系统非线性振动定量分析

Quantitative Analysis of Nonlinear Vibration of Two-Degree-of-Freedom System of Railway Vehicles

建立了以动车组1/4车体、1/2构架、三次多项式拟合的空气弹簧非线性模型为研究对象的车辆二自由度的非线性动力学模型,采用增量谐波平衡法(IHB)分析了二系垂向阻尼、激励幅值、非线性刚度对其主共振的影响、以及系统的超谐共振现象。结果表明,在二系垂向阻尼较小、三次非线性刚度较大或激励幅值较大等情况下,系统的幅频曲线会产生跳跃现象。超谐波共振的幅值远远小于基谐波,不具有研究价值,增量谐波平衡法具有可以清楚地表现出各阶谐波的贡献等优点。

Modern railway vehicles generally adopt two-stage vibration isolation system,and a large number of rubber parts are used in suspension components.Most rubber parts,such as air spring,stop,axle box rubber spring,have strong non-linear characteristics.Their stiffness will change with the change of load and the frequency of excitation.In traditional vehicle dynamics,rubber part is usually simplified as a linear spring-damper element.This spring-damper element does not consider the influence of its non-linear characteristics,.This paper establishes a two-degree-of-freedom non-linear dynamic model of the railway vehicle,which is based on the 1/4 body,1/2 frame and the cubic polynomial fitting model of the air spring of the EMU.The incremental harmonic balance method(IHB)is used to analyze the effects of the vertical damping of secondary suspension,excitation amplitude and nonlinear stiffness on its primary resonance,and the super-harmonic resonance of the system.The results show that the amplitude-frequency curve of the system will encounter the jump phenomenon when the vertical damping of the secondary system is small or the third-order nonlinear stiffness is too large or the excitation amplitude is too large.The amplitude of super-harmonic resonance is much smaller than the first harmonics,and has no research value.The incremental harmonic balance method has the advantages of clearly showing the contribution of various harmonics.