某型航空子午线轮胎刚度仿真分析

轮胎力学特性是飞机地面运动学研究的重要课题之一。基于轮胎静刚度的形成机理,忽略胎面花纹,建立某型航空子午线轮胎三维非线性有限元分析模型。考虑到航空轮胎材料非线性、几何非线性、接触非线性等问题,借助ABAQUS和HYPERMESH软件,并在ABAQUS/STANDARD求解器下进行径向和侧向刚度特性仿真分析,得出不同充气压力工况下的相应的负荷与变形的关系。通过仿真分析结果与理论估算值的对比,表明所建立的有限元分析模型可较好模拟该型航空轮胎的刚度特性。     

高速电梯安全钳制动摩擦温升的有限元分析

高速电梯对安全钳材料性能提出了更高的要求,在安全钳制动过程中,钳块与导轨间高速摩擦带来的温升可能会导致安全钳性能的退化。以ABAQUS软件为平台建立安全钳导轨系统的有限元模型,对钳块和导轨间的摩擦行为提出了一种更符合实际工况的理论新模型并编写ABAQUS子程序实现,该模型中用到的参数通过对钳块材料进行力学实验获得。通过对钳块与导轨间摩擦生热过程的仿真,考察最高温升是否超过允许值,实现对钳块安全性能的检验。仿真结果表明在高速摩擦环境下,钳块表面高温区域温升剧烈,同时钳块和导轨间的接触热导对于钳块表面的最大温升有显著影响。     

碳化硅陶瓷摩擦磨损性能及摩擦过程中接触应力分析

采用MMW-1A多功能立式摩擦磨损试验机,以全因子设计的方法研究干摩擦条件下,载荷和转速两因素对摩擦因数与磨损量的影响。摩擦因数与磨损量的方差分析结果表明,转速对摩擦因数的影响更为显著,而载荷对Si C磨损量的影响更为显著。结合ABAQUS有限元分析软件对Si C陶瓷与45#钢的摩擦过程进行模拟仿真,得到摩擦过程中接触区域的应力分布,同时还探讨Si C陶瓷的磨损机制。结果表明:Si C陶瓷表面的最大等效应力位于接触区边缘,最大拉应力位于滑动前方,最大压应力位于滑动后方;不同应力下Si C陶瓷表面的磨损机制也不一样,主要表现为黏着磨损、磨粒磨损、犁沟磨损。     

汽车车轮模型的开发与仿真验证

针对现有轮胎模型应用中存在的不足,开发了考虑气胎弹性的汽车车轮模型。模型用六向弹簧阻尼器模拟了气胎的弹性,并为接地印迹块外力计算创造了条件,接地印迹块与地面的接触摩擦采用动静摩擦分离的建模方法进行建模,准确计算了车辆在零速度附近的受力。通过对零速度工况、原地转向工况、转向小干扰工况、操纵稳定性工况的仿真,验证了模型的正确性。     

行驶面宽和行驶面高对子午线轮胎滚动阻力的影响

以载重子午线轮胎385/65R22.5为研究对象,借助ABAQUS有限元软件,建立其滚动阻力计算分析模型。在此基础上,采用数值方法对比分析了不同行驶面宽和行驶面高对轮胎滚动阻力的影响,并从胎体受载形变及轮胎各部位能量损失的角度,阐述了行驶面宽和行驶面高的变化对轮胎滚动阻力的影响规律。结果表明,行驶面宽的变化对轮胎滚动阻力影响较小。随着行驶面宽的增加,轮胎滚动阻力呈现先减小后增大再减小的变化趋势,且存在低滚阻轮胎的最佳行驶面宽;行驶面宽的变化对轮胎受载形变影响较小,但会引起轮胎不同部位能量损失的明显变化。行驶面高的变化对轮胎滚动阻力影响较大。随着行驶面高的增加,轮胎滚动阻力有变大的趋势,但这不适用于行驶面高较小时的情形;行驶面高对轮胎受载形变有明显的影响,较大的行驶面高会增加轮胎胎冠部位的压缩变形及胎肩处的弯曲变形,减少胎侧部位的弯曲变形;行驶面高的增加加大了胎冠部位的能量损失,但减小了胎体、胎侧、三角胶部位的能量损失。     

轮胎接地特性分析及试验验证

以道路简化模型和轮胎模型构成的车—路系统为对象,在ABAQUS平台上建立了轮胎的有限元分析模型,模拟了荷载作用下轮胎的接地特性。利用Table Curve平台对仿真结果进行处理,得出了轮胎接地面积计算的定量表述公式,提出了使用接地形状系数来判断轮胎接地形状的新方法。最后通过自行开发设计的一套试验装置对模拟数据进行了验证,试验结果与数值计算结果基本一致。该研究对于改进轮胎设计思路,提高轮胎使用寿命、改善车辆操控性和稳定性都具有重要指导意义。     

不同路面工况下的整车振动模态能量分析

对七自由度整车振动模型进行研究,并搭建了包含随机平直路、斜坡路、连续减速带三种路面特征的多工况路面模型。利用车辆振动模态分析理论,对不同工况下的整车振动模态能量进行分析,得到三种工况下的模态能量比及模态能量比变化率。通过MATLAB/simulink仿真分析可知,各阶模态能量比及其变化率的数值在三种路面下分布在不同的数值段,若将模态能量比与模态能量比变化率相结合能够实现对不同路面工况的区分。仿真分析结果可以为汽车行驶路面特征识别研究奠定基础。     

基于接地性态和解析方法的轮胎减磨优化及影响规律研究

接地性态是轮胎磨损的重要影响因素。本文结合轮胎刷子模型和环模型,建立了基于接地性态的轮胎磨损数学解析模型,并利用粒子群优化算法对轮胎进行了减磨优化。结果表明,接地性态中最大接地压力与滚动阻力矩是影响轮胎磨损量的最主要因素,接地长度在优化过程中的变化不明显,接地压力非对称性指数对轮胎磨损量影响的规律性较弱。研究结果可以为轮胎的减磨优化提供一种可供借鉴的思路。     

基于模糊理论的车辆直线行驶垂向力估算

针对目前国内轮胎力估算算法精度低、响应慢等问题,考虑风载的影响,在MATLAB/Simulink环境下采用模糊算法选择合适的隶属度函数对轮胎垂向力进行估算,并在不同的直线行驶工况下进行仿真验证.结果表明:不同工况直线行驶时轮胎垂向力估算值与实际值比较吻合,该算法可以较好地估算直线行驶时轮胎的垂向力,且具有较高的精度.     

基于模糊逻辑控制的混合动力汽车能量管理系统研究

介绍了模糊逻辑控制在混合动力汽车能量管理系统中的应用,在Advisor环境下,基于Mat-lab/Si mulink软件建立了混合动力汽车的仿真模型,选择反映中国高速路况Hyzem-highway和城市循环工况Hyzem-ruyal道路行驶循环分析了整车经济性能和排放性能以及制动能量管理,计算机仿真表明,在能量管理系统中使用模糊逻辑控制器是合适的。     

Tire wear by ablation

The transient temperature profile of a slipping tire is calculated by taking into account the frictional heating due to slip, temperature build-up due to hysteresis, convection and radiation loss into the air, and conduction cooling into the ground. Specific attention is directed to the calculation of tire surface temperature. Calculated surface temperature shows a value which may exceed the melting point of tread rubber. The phase change of the tread rubber at the surface leads to a particular wear mechanism. Wear of the tire is calculated for the transient process which occurs at the contact area between tire and ground.The governing equations for temperature profile and the associated wear process are solved numerically by a finite difference technique. Tire surface temperatures for different service conditions agree well with the available data for automobile tires. Tire wear data agree with those reported for airplane tires. The proposed wear model may be applicable to automobile tires when the service condition is severe.From the thermal analysis one can see the effect of surface properties of both tire and ground on the wear process. Other parameter studies provide some information about the effects of some important factors on tire wear.     

Numerical calculation of irregular tire wear caused by tread self-excited vibration and sensitivity analysis

Tire wear negatively affects vehicle safety and riding comfort. Abnormal wear is more dangerous and wears tires out more quickly. In this paper, numerical and sensitivity analyses of polygonal wear caused by unstable vibration are presented. The model used for this study was based on the works of Sueoka. Tread self-excited vibration was analyzed in a quantitative sense, which was qualitatively different from the work of Sueoka. Wear was plotted on tire circumference visually. The mechanism governing polygonal tire wear was investigated as that both the polygonal wear and the standing wave are caused by two types of tread vibrations that only differ in the extent of the tread vibration. Sensitivity analysis shows that decreases in tread mass and stiffness and increases in tread damping lead to noticeable reductions in tire wear. This information could help tire manufacturers produce tires that exhibit less wear caused by tread vibration.     

基于有限元法分析高速切削时摩擦系数对高速切削的影响

为了探究高速切削时,刀具与切屑间摩擦系数对切削的影响,采用有限元通用程序ABAQUS／Explicit,对不同摩擦系数下正交切削过程进行数值模拟。据此研究了刀具摩擦系数对高速切削中切屑变形、切削力的影响。     

Tread wear and footprint geometrical characters of truck bus radial tires

Wear and mileage performance are the foremost performances for truck bus radial (TBR) tires. There are a lot of researches about the tire wear performance as well as the contact patch phenomenon by using finite element analysis (FEA) method or testing. But there is little published data on the correlations between the footprint geometry and the tread wear performance of tires. In this paper, an experiment on tire-ground performance of TBR tires is carried out by using Tekscan. The real-time changes of contact-area pressure distribution that occurred during the process of continuous load and unload are recorded. Three types of tires that act differently in behavior under normal usage are analyzed. A new method of researching in tire tread wear, which focuses on the geometrical characters of the footprint, is put forward. The experimental results of the three tires are described by using footprint geometrical characters. On the basis of studying the changing laws of footprint geometrical characters during the loading process and considering consumer survey and factory feedback information, the correlations between the geometrical character of footprints and tread destruction form are built. The analyzed results show that a greater contact area coefficient and a steady coefficient of contact result in a better wear performance for TBR tires. The footprint-shape coefficient changing laws in the process of loading are found to have a very good coincidence with the tread wear of the three types of tires. Tires with a smaller footprint-shape coefficient are likely to have an average tread wear while avoiding the shoulder wear first. The proposed research provides a new solution to predict tire-ground performance at the point of footprint and several useful references for improving tire design.     

[轮轨磨耗及预测]列车紧急制动过程中踏面温度分布及磨耗预测

列车紧急制动过程中踏面温度急剧升高导致车轮踏面的摩擦磨损机理与稳态运行时有显著差异。为了准确预测列车紧急制动过程中踏面磨耗,同时考虑踏面制动过程中车轮踏面与钢轨及闸瓦接触,基于有限元软件ABAQUS建立了踏面制动过程热机械耦合有限元模型,综合考虑制动温升对车轮踏面力学性能、硬度及摩擦因数的影响,仿真得到了紧急制动过程中车轮踏面上温度分布、硬度分布以及接触应力分布,并利用轮轨动力学软件UM得到了紧急制动过程中轮轨接触斑形状以及轮轨蠕滑区相对滑移分布,在此基础上结合Archard磨耗模型对单次紧急制动结束后的踏面磨损深度进行了定量预测。结果表明：对于制动初速度为130 km/h、160 km/h两种工况,踏面最高温度分别达到了397.0 ℃和485.9 ℃,踏面最大累积磨损深度分别为5.90 μm和7.43 μm,与踏面制动实验对比发现,预测结果与实验结果磨损位置及形貌分布趋势一致。     

Shape design of a tire contour based on approximation model

The basic purpose of a tire is to enhance vehicle performances such as driving performance, rolling resistance, durability, ride comfort, noise, wear resistance, etc. by acting as a flexible cushion. To meet the demand for increased vehicle performances, the design method of a tire has advanced. This study proposes a structural design method for tire contour by considering both the tread contour and the sidewall contour, simultaneously. Existing studies of tire contour optimization have focused on the tread contour and the sidewall, separately. Durability, maneuverability and ride comfort are performances that are commonly investigated in tire contour design. Durability, maneuverability and ride comfort can be measured by the values of the strain energy density, tension and vertical stiffness, respectively. The optimization technique using a metamodel is introduced to maximize durability while satisfying the imposed constraints of tension and ride comfort. To achieve this, the responses defined in the optimization formulation are expressed mathematically in explicit form with respect to the design variables by using the kriging surrogate model, resulting in a simple optimization problem. Then, the simulated annealing algorithm is utilized to find the global optimum.     

Texture characteristics of unpolished and polished aggregate surfaces

In order to investigate evolution of polishing aggregate surfaces on an aggregate wear index (AWI) wear track specimen, experimental texture measurements and data dependent system (DDS) approach were utilized to model and analyze elevation profiles collected from unpolished and polished aggregate surfaces. It was found that the DDS approach was able to characterize the evolved macrotexture and microtexture. The polishing effect induced by the interaction between tire tread and aggregate surfaces was found to reduce the microtexture roughness significantly, but showed little influence on the macrotexture. This does not imply that the macrotexture plays little role in tire tread friction. It was also found that polishing effect presented a strong relationship with grain size existing on aggregate surfaces.     

基于偏相干分析的轮胎六分力信号识别

由于轮胎多边形的磨损与胎面自激振动有很大的关系,故对问题轿车进行了实车车轮六分力试验,以找出其振动规律.因为测得的六分力信号成分非常复杂,所以将其信号中的侧向力信号作了重点分析,利用偏相干分析法,排除该信号中的其他干扰频率成分,并将其自激振动的频率与计算仿真中所得到的频率作了对比,验证了理论模型的正确性.     

一种新的轮胎印痕测量及压力分布数据处理方案

介绍了一种基于压阻阵列成像方法的轮胎外圈表面花纹磨损检测技术,该技术通过检测轮胎在特定载荷下印痕的变化来估计轮胎的质量与使用寿命。在介绍测量原理的基础上,重点介绍了印痕图像处理技术与评价方法,针对轮胎花纹与地面接触产生的印痕图像确定边界与接触面积,研究了一种基于圆模板滚边的方法来获取图像外包络线的算法。研究表明该方法能有效处理凸壳与非凸壳图形,自动获取带凹槽图形的外包络区域,具有较好的鲁棒性和较高的精度。     

轮胎胎面参数在线检测系统研究及应用

为了提高汽车轮胎生产过程中对胎面尺寸的测量精度,针对移动中的橡胶胎面设计了一种测量轮胎胎面参数的在线检测系统。选用3D激光传感器,根据传感器获得的坐标数据绘出胎面横截面轮廓,基于B样条曲线拟合方法,通过特征点测量计算胎面横截面数据;选用CCD图像传感器,设置两端基准线,根据现场亮度采用可调光源控制器,并采用OSTU算法对图像进行二值化处理,基于像素数和实际的尺寸存在线性对应关系,可获得胎面长度。现场实验结果表明,该测量系统的横截面参数测量精度小于1 mm,长度测量精度小于2 mm,能够满足生产工艺的测量要求,可实现胎面参数的在线动态测量,该测量系统具有安装方便、运行稳定等特点。