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1.
电梯导轮和导轨相互作用产生的高频振动是电梯噪音的主要来源之一,本文基于导轨、导轮和电梯框架等各柔性构件的频响函数,建立了耦合振动系统的频域计算模型。分析了导轨表面粗糙度、导轮偏心和扁疤等激励对电梯高频振动的影响。通过与实测数据进行比较.验证了计算模型的有效性.从而为电梯的减振降噪设计提供了有用的分析工具。  相似文献   

2.
王庚祥  马道林  刘洋  刘才山 《力学学报》2022,54(12):3239-3266
接触碰撞行为作为大自然与多体系统中的常见现象,其接触力模型对于多体系统的碰撞行为机理研究与性能预测至关重要.静态弹塑性接触模型与考虑能量耗散的连续接触力模型是研究接触碰撞行为的两类不同方法,在多体系统碰撞动力学中存在诸多共性与差异.本文分别从上述两类接触模型的发展历程入手,详细介绍了两类模型的区别与联系.首先,根据阻尼项分母中是否含有初始碰撞速度将连续接触力模型分为黏性接触力模型与迟滞接触力模型,讨论了能量指数与Hertz接触刚度之间的关系,阐述了现有连续接触力模型在计算弹塑性材料接触碰撞行为时存在的问题.其次,着重介绍了分段连续的准静态弹塑性接触力模型(可连续从完全弹性转换到完全塑性接触阶段),分析了利用此类弹塑性接触力模型计算碰撞行为的技术特点.同时,以恢复系数为桥梁和借助线性化的弹塑性接触刚度,避免了Hertz刚度对弹塑性接触刚度的计算误差,根据碰撞前后多体系统的能量与动能守恒推导了弹塑性接触模型等效的迟滞阻尼因子.探索了连续接触力模型与准静态弹塑性接触力模型之间的内在联系,数值计算结果定量说明了人为阻尼项代表的能量耗散与弹塑性接触力模型中加卸载路径代表的能量耗散具有等效性.另外...  相似文献   

3.
表面接触是摩擦的先决条件,其真实接触面积、压应力大小、空间分布等一直是接触力学关注的核心问题.采用分子动力学-格林函数法(GFMD)模拟粗糙面的接触过程,验证了其在大规模接触分析中的高效及准确性,同时探讨了由微球体组成的粗糙面的接触力学特性,并分析了分子尺度下的结果和传统力学模型计算结果的差异.结果表明,单个微凸体接触结果和分子动力学-格林函数法模拟所得非常接近,误差在5%以内.数值模拟发现,在微凸体高度符合高斯分布的情况下,接触面积和接触力成线性关系;在相同接触面积下,微凸体模型得出的接触力偏高,是上限值.微凸体模型没有考虑微凸体间的相互影响,实际是高估了弹性体的刚度;实际接触过程中微凸体相互影响,微凸体对临域形变影响尤其大,使接触区域更加离散.GFMD模型可以准确计算数十亿量级别分子、原子接触过程中真实接触面积及分布,为后续摩擦、滑移等分析提供可靠的参考.  相似文献   

4.
传统在轨分离载荷动力学分析未考虑实际导轨的实时接触,无法准确分析分离时刻载荷的速度和角速度。针对半圆形双导轨,研究了空间导轨与定向器接触的特点及形式,基于分离装置的几何构型提出了一种确定发生相对轴向运动时导轨与定向器潜在接触对的方法,所提方法考虑了载荷轴线与导轨轴线的空间夹角,保证了分离后期接触检测的准确性,并可推广至多导轨接触计算。基于Lankarani与Nikravesh的连续接触力模型计算法向碰撞力,采用修正的Coulomb模型计算切向摩擦力。最后对飘浮基挠性航天器在轨分离载荷模型进行数值分析,验证了方法的有效性。结果表明导轨间隙增大了接触碰撞力,且随间隙的增大垂直于载荷分离方向的速度和角速度增大,导轨间隙使基座的转动与挠性附件强烈耦合,对航天器的稳定性造成影响。  相似文献   

5.
轨道随机不平顺作为引起车辆-轨道-桥梁耦合系统振动的最重要的激励源,对列车过桥平稳性有着至关重要的影响.建立车辆-轨道-桥梁耦合垂向振动模型,采用虚拟激励法,计算随机不平顺激励下车辆运行的平稳性以及轨道和桥梁结构的振动特性,避免了繁复的时频转换和复杂的数值积分.数值分析了不同速度下列车过桥的平稳性和列车对不平顺波长的敏感范围.经过分析得到,列车运行速度越大,过桥平稳性指标越大,即舒适性越差;而且影响列车平稳性的不平顺波长越长,其影响范围越大.  相似文献   

6.
高速电梯运行时,井道内气压的快速变化会对轿厢运行的稳定性及安全性产生极大影响.为解决上述问题,提出了三种在井道壁面上开风口的设计方案,运用计算流体力学分析软件FLUENT对电梯运行过程中的空气流动状态进行数值仿真,同时改变风口形状以及数量,对井道内风速变化、轿厢所受气动阻力及气动力矩进行分析.分析结果表明,在提出的三种开风口方案中,上下圆形风口为最优,与未开风口时相比,轿厢气动阻力减小22.05 %,侧翻力矩减小29.87 %,俯仰力矩减小18.02 %.最后进行试验验证,表明了开风口方案的有效性,研究结果可为井道风口的设计提供理论依据.  相似文献   

7.
将凸轮与平底从动件接触视为二维线性接触,基于无限大半空间模型对从动件的变形量进行了分析,利用圆柱体二维线接触变形的计算方法对凸轮接触变形进行了计算,从而得到了凸轮与平底从动件的接触变形量与接触刚度理论计算公式。利用Palmgren公式和有限元方法对计算公式进行了验证,并分析了接触刚度与凸轮曲率半径、接触力之间的关系,结果表明:接触应力、接触半宽、凸轮接触变形量的理论计算值与有限元计算结果几乎相等,凸轮与从动件的接触变形量之和的理论计算值与有限元计算值相差小于5%;凸轮与平底从动件的接触变形之和、接触刚度都与接触处凸轮的曲率半径无关,而与凸轮与平底从动件间的接触力大小有关。  相似文献   

8.
讨论了应用Newmark-β直接积分法求解冲击-动力接触问题在初始接触和初始分离时进行修正的必要性;证明了基于Newmark方法的有效刚度阵的正定性,导出了关于接触力向量的有效柔度方程,从而把动力接触迭代过程凝缩到接触面上,提高了计算的效率;算例包括两杆冲击问题和两圆盘冲击问题。  相似文献   

9.
高速电梯系统时变动力学模型与分析   总被引:1,自引:0,他引:1  
胡振东  赵姗姗 《力学季刊》2002,23(3):422-426
以往关于电梯系统的研究指出,引起电梯系统振动的主要原因在于外部激励-由曳引机,承重装置,拖动和控制系统等引起。这是基于经典的结构共振理论得出的结论,但不能解释某些电梯的振动行为。本文从时变结构力学的观点出发,计及电梯曳引钢丝绳的长度随时间变化,建立起电梯系统的变刚度动力学模型,采用解析方法给出了高速电梯弹性振动的位移和加速度响应表达式。从理论上证明作为时变系统的电梯,具有振荡运动的特征,存在由变刚度引起的自激振动。进一步研究表明,电梯提速意味着曳引钢丝绳的初始扰动增大,导致电梯振动的加速度也增大,对电梯的舒适性有负面影响。  相似文献   

10.
范坤  杨珍  薛晓敏  夏洪利 《应用力学学报》2020,(5):1887-1893+2311
单轨火箭橇靴-轨的冲击响应是影响其运动过程中系统稳定性的主要问题。本文以单轨火箭橇为研究对象,采用有限元结构动力学仿真分析方法建立了非线性火箭橇-轨道耦合动力学模型;对比分析了理想平直轨和不平顺轨两种轨道模型条件下滑靴、卡环、发动机的振动量变化,并进行了火箭橇的试验验证和数据对比。结果表明:不平顺轨道对火箭橇靴-轨冲击响应振动加速度均方根值的影响大于理想平直轨道,滑靴处二者最大偏差为3~5倍,且随机振动特性显著;最大速度时刻的靴-轨冲击预测结果与实测值在侧向和竖向振动趋势上具有很好的一致性。研究结果为火箭橇结构优化设计及稳定性分析提供了理论依据和技术保障。  相似文献   

11.
轨下支承失效对直线轨道动态响应的影响   总被引:5,自引:0,他引:5  
建立了基于Timoshenko梁模型的车辆/轨道耦合动力学模型,分析轨下支承失效对直线轨道动态响应的影响. 钢轨被视为连续弹性离散点支承上的无限长Timoshenko梁,通过假设轨道系统刚度沿纵向分布发生突变来模拟轨下支承失效状态. 推导了考虑钢轨横向、垂向和扭转运动的轮轨滚动接触蠕滑率计算公式. 利用Hertz法向接触理论和沈氏蠕滑理论计算轮轨法向力及轮轨滚动接触蠕滑力. 采用移动轨下支承模型的车辆/轨道耦合系统激振模式,考虑轨枕离散支承对系统动力响应的影响. 通过新型显式积分法求解车辆/轨道耦合动力学系统运动方程,由数值分析计算得到不同轨下支承失效状态下直线轨道的动态响应. 结果表明,轨下支承失效对直线轨道变形及加速度有显著的影响,随着失效轨下支承个数的增加,轮轨相互作用力和轨道部件的位移、加速度将会急剧增大,将加速失效区段线路状况的恶化.   相似文献   

12.
As a vehicle passing through a track with different weld irregularities, the dynamic performance of track com- ponents is investigated in detail by using a coupled vehi- cle-track model. In the model, the vehicle is modeled as a multi-body system with 35 degrees of freedom, and a Timoshenko beam is used to model the rails which are dis- cretely supported by sleepers. In the track model, the sleepers are modeled as rigid bodies accounting for their vertical, lat- eral and rolling motions and assumed to move backward at a constant speed to simulate the vehicle running along the track at the same speed. In the study of the coupled vehicle and track dynamics, the Hertizian contact theory and the theory proposed by Shen-Hedrick-Elkins are, respectively, used to calculate normal and creep forces between the wheel and the rails. In the calculation of the normal forces, the coefficient of the normal contact stiffness is determined by transient contact condition of the wheel and rail surface. In the calcu- lation of the creepages, the lateral, roll-over motions of the rail and the fact that the relative velocity between the wheel and rail in their common normal direction is equal to zero are simultaneously taken into account. The motion equations of the vehicle and track are solved by means of an explicit integration method, in which the rail weld irregularities are modeled as local track vertical deviations described by some ideal cosine functions. The effects of the train speed, the axle load, the wavelength and depth of the irregularities, and the weld center position in a sleeper span on the wheel-rail impact loading are analyzed. The numerical results obtained are greatly useful in the tolerance design of welded rail pro- file irregularity caused by hand-grinding after rail welding and track maintenances.  相似文献   

13.
The paper is devoted to the experimental, theoretical analysis and computer simulation of influence of elastic properties of contact stiffness and wheel-plate stiffness on the forces of vehicle-track interaction. Three types of wheels are considered with different contact stiffness and wheel-plate design. Exemplary simulation of freight car interaction with track which posses one corrugated rail for each type of wheel is presented.  相似文献   

14.
This paper presents a framework for simulating railway vehicle and track interaction in cross-wind. Each 4-axle vehicle in a train is modeled by a 27-degree-of-freedom dynamic system. Two parallel rails of a track are modeled as two continuous beams supported by a discrete-elastic foundation of three layers with sleepers and ballasts included. The vehicle subsystem and the track subsystem are coupled through contacts between wheels and rails based on contact theory. Vertical and lateral rail irregularities simulated using an inverse Fourier transform are also taken into consideration. The simulation of steady and unsteady aerodynamic forces on a moving railway vehicle in cross-wind is then discussed in the time domain. The Hilber–Hughes–Taylor α-method is employed to solve the nonlinear equations of motion of coupled vehicle and track systems in cross-wind. The proposed framework is finally applied to a railway vehicle running on a straight track substructure in cross-wind. The safety and comfort performance of the moving vehicle in cross-wind are discussed. The results demonstrate that the proposed framework and the associated computer program can be used to investigate interaction problems of railway vehicles with track in cross-wind.  相似文献   

15.
为了考虑高速列车、板式无砟轨道和桥梁相互作用的特点,需将列车模拟为质量-弹簧-阻尼多刚体相互约束的系统,通过列车车轮与钢轨的接触关系,建立车-轨-桥耦合系统的运动方程。重点分析了双线列车以不同工况通过高速铁路桥梁时,列车行驶状态(速度和加速度)、列车悬挂系数和钢轨-轨道-桥梁连接参数分别对车-轨-桥耦合系统的动力学性能影响。结果表明,(1)列车的加速度和速度的变化对耦合系统有不同程度的影响,随着列车行驶速度与加速度在一定范围内增加,车体自身结构的位移振动响应逐渐减小,而钢轨和桥梁结构的位移振动响应则不断增加;(2)列车悬挂参数的改变对列车自身结构影响较大,而对钢轨和桥梁结构影响很小;(3)车体一系刚度系数增大会引起列车系统结构振动响应变大,但车体二系刚度系数的增加却抑制了车体结构的振动响应;(4)除了钢轨的最大加速度随着连续刚度系数增加呈线性递减外,列车、钢轨和桥梁的振动响应不易受钢轨与桥梁间连接参数的影响。  相似文献   

16.
Based on Biot’s fully dynamic poroelastic theory, the dynamic responses of the poroelastic half-space soil medium due to quasi-static and dynamic loads from a moving train are investigated semi-analytically. The dynamic loads are assumed to be generated from the rail surface irregularities. The vehicle dynamics model is used to simulate the axle loads (quasi-static loads) and the dynamic loads from a moving train. The compatibility of the displacements at wheel–rail contact points couple the vehicle and the track–ground subsystem, and yield equations for the dynamic wheel–rail loads. A linearized Hertzian contact spring between the wheel and rail is introduced to calculate the dynamic loads. Using the Fourier transform, the governing equations for the poroelastic half-space are then solved in the frequency–wavenumber domain. The time domain responses are evaluated by the fast inverse Fourier transform. Numerical results show that the dynamic loads can make important contribution to dynamic response of the poroelastic half-space for different train speed, and the dynamically induced responses lie in a higher frequency range. The ground vibrations caused by the moving train can be intensified as the primary suspension stiffness of the vehicle increases.  相似文献   

17.
Summary In the paper, dynamic interaction between elastic high-speed-train car wheelset and track is studied using a discrete-continuous mechanical model. The model enables to investigate the influence of the parametric excitation from the track as well as static and dynamic unbalances of wheels and brake disks on the dynamic response of the wheelset running at various speeds on the track of various average vertical stiffness. From the results of numerical simulation it follows that particularly severe periodic resonances occur for the track of large stiffness, yielding high vertical dynamic contact forces between the wheels and rails. The maximum dynamic response has been obtained for parameters corresponding to the conditions at which the phenomenon of grumbling noise generation is usually observed in reality. Received 21 January 1997; accepted for publication 29 February 1997  相似文献   

18.
针对密贴和弹簧连接两种轮轨关系模型,通过构造车轮与桥梁之间相对位移和相互作用力间的线性互补关系,建立了两种考虑轮轨脱离的车桥耦合系统动力学分析模型,从而将车桥耦合系统的轮轨连接问题转化为标准的线性互补问题。本文方法不需要在每一个时间步对接触状态进行判断,避免了传统算法的迭代求解过程,能够对轮轨脱离进行模拟。在数值算例中,讨论了无量纲化的车桥耦合系统质量、刚度等参数和行驶状态对系统响应动力放大系数的影响,以及速度因子和车桥质量因子对轮轨脱离的影响。数值算例证明了本文方法的正确性,且相对于传统轮轨接触模型具有更高的计算效率。  相似文献   

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