【作者】 王国新；

【导师】 陈光雄；

【作者基本信息】 西南交通大学 ， 机械电子工程， 2010， 硕士

【摘要】 铁路噪声问题因其对环境的负面影响而引起了人们的广泛关注；同时,也制约着高速铁路和城市轨道交通的发展。一些线路不可避免地存在小半径曲线,伴随发生的曲线尖叫噪声是轮轨噪声的主要形式之一。因涉及到动力学、摩擦学和声学振动领域的交叉,曲线尖叫噪声问题变得十分复杂。本文的工作从研究车辆通过小半径曲线时轮轨系统的摩擦振动稳定性入手,根据振动失稳同噪声之间的联系,阐述曲线尖叫噪声的产生机理,分析不稳定振动的模态特征参数,研究摩擦行为在轮轨振动耦合过程中的作用。建立了由轮对、钢轨和轨道支撑单元构成的轮轨系统三维实体有限元模型,计算结果表明：(1)横向饱和蠕滑力的耦合作用导致轮轨振动出现动态失稳,引起曲线尖叫噪声。噪声的振源为内侧轮轨,以车轮轮辋的轴向振动和钢轨的垂向振动为主。(2)声源的振动属于摩擦自激振动。轮轨自激振动的机理是轮辋的轴向振动模态和钢轨的垂向振动模态发生耦合。(3)摩擦系数直接制约着系统的稳定性。对于系统存在的诸多不稳定模态个体而言,存在着临界摩擦系数。当摩擦系数大于某个不稳定模态的临界摩擦系数时,轮轨系统出现对应频率的自激振动。(4)轨道支撑刚度影响着摩擦力的耦合效应的强弱。这种影响实质上是由垂向支撑刚度决定的,与横向支撑刚度无关。存在着抑制、增强和微弱影响三种作用形式,对应着不同的不稳定模态个体。理论上,存在理想的轨道支撑刚度以降低尖叫噪声发生的可能性。(5)轴重的差异没有引起系统稳定性明显的变化。在一定程度上,轮轨间摩擦力的大小不是引起系统振动失稳的关键性因素。更多还原

【Abstract】 Railway noise is a public’s main concern because of its negative influence on the environment, and it restricts further developments of high-speed railway and urban rail transit. A sharp curve is usually unavoidable in some railway lines, and the consequent curve squeal is one of main components of railway noise. Curve squeal is a complicated problem due to the many physical interactions of dynamical, tribological and acoustical behaviour.The main research purpose of this paper is to estimate the dynamic stability of wheelset-track system during curve negotiation. According to the relationship between the noise and the unstable vibration, the formation mechanism of curve squeal and the modal characteristics of the unstable vibration are investigated. Specially, the effect of frictional behaviour on the mode-merging of the system is described in detail. A 3D solid finite element model of a wheelset-track system is established, which includes a wheelset, two rails and a series of track support elements. The investigation leads to the following conclusions:(1) Unstable vibration of wheels and rails radiates the curve squeal, which is induced by the coupling effect of lateral saturated creep forces. The squealing noise source is attributed to the vibration of the inner wheel in the axial direction and the vibration of the low rail in the normal direction.(2) Curve squeal is generated as a result of self-exited vibration. The formation mechanism of curve squeal is the occurrence of mode-merging between the axial mode of the inner wheel and vertical mode of the low rail.(3) The friction coefficient has a significant influence on the stability of the wheelset-track system. There is a critical friction coefficient for each unstable mode. When the friction coefficient is larger than the critical value, a self-excited vibration of the wheelset-track system associated with the unstable modal frequency will occur.(4) The support spring stiffness is very influential on the stability of the system. The vertical support spring stiffness is essential but the lateral support spring stiffness only has a small influence. Different vertical support spring stiffness may suppress, enhance or slightly influence unstable vibration of the wheelset-track system. There is an optimal vertical support stiffness, applying which can largely suppress or eliminate the curve squeal. (5) The stability of the wheelset-track system does not have an obvious change for different axle loads. The magnitude of the friction forces between wheels and rails are not crucial for the instability of the wheelset-track system in some degree.更多还原