【作者】 杨帆；

【导师】 王平；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2020， 博士

【摘要】 随着高速铁路网迅速发展及线路服役期安全运维管理需求,高速铁路无砟轨道结构中累积结构损伤的迅速增加,比如高频轮轨激励引起的钢轨波纹磨耗、不规则车轮廓形、扣件弹条断裂和轨道板裂纹等问题。为了准确预测、分析和控制高频轮轨力,对轮轨耦合系统高频振动动力学进行了大量研究,其中包括对车辆和轨道系统的模型细化、轮轨耦合关系和车辆轨道系统中粘弹性橡胶材料非线性动力学模型的研究。橡胶材料的动力学性能对外部荷载幅值、频率及环境温度具有强烈的依赖性,导致车辆轨道耦合系统在对极寒气候条件与轮轨高频随机激励作用的下振动特征变得错综复杂。然而已有的铁路系统动力学问题的研究中往往考虑的因素不够全面,使得轮轨耦合振动响应在高频区域的精度依然差强人意。因此,建立更为合理、精确、高效的车辆轨道耦合动力学模型,提高车辆轨道耦合系统在高频范围内的理论预测能力具有重要意义。本论文受到国家杰出青年科学基金项目“高速铁路轨道结构服役安全关键科学问题研究(51425804)”和“国家留学委员会基金”等基金项目的资助,开展了车辆轨道耦合系统非线性动力学模型及其在改善极寒地区轨道结构振动中的应用研究,主要研究内容如下:1.利用非线性Berg摩擦力模型与分数阶导数Zener模型分别对粘弹性橡胶材料荷载幅值与频率依赖性进行建模,建立了单自由度系统的非线性分数阶导数Zener模型。提出了简化的Berg摩擦力模型应用到频域分析模型中,使得非线性单自由度系统的分数阶导数Zener模型能够直接在频域内求解。对含有粘弹性橡胶隔振器的单自由度系统的动力学响应进行计算分析研究,验证了本文提出的非线性分数阶导数Zener本构模型的精确性。2.同时考虑了轮轨耦合系统中一系悬挂橡胶弹簧与扣件胶垫的动力学行为对荷载频率与幅值的依赖性,在时域和频域内建立了钢轨梁单元的车辆轨道耦合系统非线性分数阶导数Zener模型,并利用简化的Berg摩擦力模型方法以提高模型在频域内的计算效率。通过与时域结果傅里叶变换获得的频域响应进行比较,验证了本文提出的频域内直接求解模型,并深入地研究了该模型的计算精度与参数敏感性分析。3.利用铁木辛柯梁+质量块对轮对结构建模,通过有限元实体单元模拟钢轨结构,并结合在高频区域内对粘弹性材料动力学行为具有更高表达精度的分数阶Zener模型对车辆一系橡胶弹簧与扣件胶垫建模,建立了车辆轨道耦合系统空间垂向非线性分数阶Zener精细模型。结合模态叠加法求解耦合系统的时频域动力学响应,使得提出的模型不仅具有很高的计算精度,同时保证了较高的计算效率。钢轨实体单元与铁木辛柯梁单元对应的转向架加速度频域响应差异由于一系悬挂系统可以忽略不计,钢轨铁木辛柯梁单元模型的轮轨力响应精度不能满足2000Hz以上高频区域轮轨耦合振动分析。是否考虑轮对梁+质量块模型对转向架加速度响应第一主频处峰值响应差异为11%,对轮对加速度响应影响在整个频域内均较大,位于118.4Hz,879.4Hz及2166.4Hz处多出了3个响应波峰,这是由于左右钢轨的对称荷载使得轮对弹性模型的对称模态受到激发。而两种轮对模型下钢轨加速度与轮轨力响应仅在118.4Hz有较大差异。计算分析了钢轨点支撑与面支撑模型的车轨耦合随机振动响应,两种支撑模型对转向架加速度响应的影响可以忽略不计,轮对、钢轨以及轮轨力响应在两种约束模型下位于第一主频64.3Hz处差异仅为0.1%,但是在1000Hz附近峰值差异超过了41%,位于2650Hz处响应峰值差异大于44%。4.极寒环境温度将引起扣件胶垫动态刚度显著增加,阻尼特性降低,极大地影响胶垫的动态力学性能。本文提出了一种带有热电发电机与加热器的新型铁路扣件系统,通过集成在铁路轨道系统中的热电发电机对清洁的环境热能加以利用,可以提供足够的功率来加热扣件胶垫。保证了胶垫在极寒气候条件下的最佳工作温度,从而改善轨道结构在极寒温度时的动力学行为,通过理论和实验研究验证了新型扣件系统的可行性。结合本文提出的车辆轨道耦合系统空间垂向分数阶Zener精细模型,对极寒气候条件下是否装有新型扣件系统的轮轨耦合随机振动响应进行计算分析。在极端寒冷的天气条件下,装有新型扣件系统的车辆轨道耦合系统的振动幅值可以降低41.5%,且振动能量向低频转移。进一步地可以根据轨道结构的设计要求给出扣件胶垫的合理工作温度范围,对极端天气下铁路轨道系统结构的设计提供一定的参考更多还原

【Abstract】 With the rapid development of high-speed railway network and the demand of safe operation and maintenance management during railway service period,the cumulative structural damage in high-speed railway ballastless track structure increases rapidly,such as rail corrugated wear caused by high-frequency wheel rail excitation,irregular wheel profile,fastener elastic bar fracture and track slab crack,etc.In order to accurately predict,analyze and control the high-frequency wheel-rail force,a large number of studies have been carried out on the high-frequency vibration dynamics of the wheel-rail coupling system,including the model refinement of the vehicle and track system,the wheel-rail interaction and the nonlinear dynamic model of viscoelastic rubber the vehicle track system.The dynamic properties of rubber materials are strongly dependent on the external load amplitude,frequency and ambient temperature,which result in the complex vibration characteristics of vehicle track coupling system under the extreme cold climate conditions and high frequency random excitation of wheel and rail.However,the factors often considered in the study of the existing railway system dynamics are not comprehensive enough,which makes the coupling vibration response of wheel-rail system still unsatisfactory in high frequency region.Therefore,it is of great significance to establish a more reasonable,accurate and efficient vehicle track dynamics model to improve the theoretical prediction ability in the high frequency range.This paper is supported by the National Outstanding Youth Science Foundation Project "Research on the Key Scientific Problems of Service Safety in High-speed Railway Track Structure(51425804)" and the scholarship under the State Scholarship Found organized by the "China Scholarship Council".The nonlinear dynamic model of vehicle track coupling system and its application in improving the vibration characteristics of track structure in extremely cold area are studied.The main research contents are as follows:1.The nonlinear Berg friction model and the fractional derivative Zener model were used to model the dependence of the load amplitude and frequency on the viscoelastic rubber material,respectively.A simplified Berg friction model is proposed and applied to the frequency domain analysis model,so that the fractional derivative Zener model of the nonlinear single degree-of-freedom(DOF)system can be solved directly in the frequency domain.The dynamic analysis of the single DOF system with viscoelastic rubber isolator is calculated and analyzed to verify the accuracy of the proposed nonlinear fractional derivative Zener constitutive model.2.Both the frequency and amplitude dependence of the dynamic behavior of the first suspension rubber springs and rail pads in the wheel-rail coupling system is considered,and the nonlinear fractional derivative Zener model of the vehicle track coupling system which models rail as beam element is established in time domain and frequency domain,respectively,and the simplified berg friction model method is used to improve the computational efficiency of the model in frequency domain.By comparing with the frequency domain response obtained by Fourier transform of the time domain results,the proposed model solved in the frequency domain directly is verified,and the calculation accuracy and parameter sensitivity analysis of the model are thoroughly studied.3.An accurate model of spatial vertical fractional derivative Zener of vehicle track coupling system is established by using the rigid mass block and Timoshenko beam,modeling the rail structure by finite element solid element,and combining the fractional derivative Zener model with higher expression accuracy for viscoelastic material dynamic behavior in high frequency.Combining the modal superposition method to solve the time/frequency domain dynamic response of the coupled system makes the proposed model not only have a high calculation accuracy,but also ensure a high calculation efficiency.Due to the vibration damping effect of the primary suspension system,the difference between the acceleration frequency response bogie under the two models of rail is negligible,and the accuracy of the wheel-rail force response of the Timoshenko beam t model of rail cannot meet the coupling vibration analysis in the high frequency range above 2000 Hz.When considering the elastic model of wheelset for the coupled vehicle-track system model,the difference of the bogie acceleration response is 11% at the first dominant frequency of wheel-rail resonance,and the effect of the acceleration response on the wheelset is great in the entire frequency domain.There are three additional response peaks at 118.4Hz,879.4Hz,and 2166.4Hz after considering the elastic model of wheelset,this is because the symmetrical load of the left and right rails excites the symmetric modes of the wheelset elastic model.However,the rail acceleration and wheel-rail force response under the two wheelset models are only significantly different at 118.4 Hz.4.The dynamic stiffness of the rail pad will be increased significantly and the damping decrease in the extreme cold environment,which will greatly affect the dynamic mechanical properties of the rail pad.A novel railway fastener system with thermoelectric generator and heater is presented.The thermoelectric generator integrated in the railway track system utilize the clean environmental thermal energy to provide sufficient power to heat the rail pad,that can ensure the optimal working temperature of the rail pad under the extremely cold weather condition,thereby improving the dynamic behavior of the track structure at the extremely cold temperature,and the feasibility of the proposed novel fastener system is verified through theoretical and experimental studies.Combined with the spatial vertical fractional derivative Zener model of the vehicle track coupling system proposed in this paper,the random vibration response of the wheel-rail coupling system with or without the novel fastener system is calculated and compared under extreme cold climate conditions.In the extreme cold weather condition,the vibration amplitude of the vehicle track coupling system equipped with the novel fastener system can be reduced by 41.5%,and the vibration energy is transferred to low frequencies.The reasonable working temperature range of the rail pad can be obtained according to the design guideline of railway track structure,which provides some reference for the design of railway track system in extreme weather.更多还原