不同花纹轮胎噪声辐射特性

轮胎噪声是交通环境噪声的主要来源之一,也是汽车噪声的主要声源。用虚拟模型预测的方法对滚动轮胎的振动辐射噪声进行预测分析。通过对滚动轮胎施加路面简谐激励,获取滚动轮胎表面加速度响应并作为声学分析的边界条件。采用边界元的方法分析不同花纹形式的滚动轮胎在路面激励下振动辐射噪声特性,结果表明花纹形式直接影响着滚动轮胎振动辐射噪声的大小,胎面花纹质量越小,振动辐射噪声越大,研究结果具有工程应用价值。     

子午线轮胎胎面花纹块滑动磨损有限元分析

该文以205/55R16半钢子午线轮胎为参考轮胎,通过建立带纵向和横向简单花纹的轮胎模型,使用ABAQUS/Standard进行了轮胎自由滚动、制动工况的有限元分析,分析了与胎面磨损分布相关的粘着滑移区域随滚动角速度变化的分布情况。结果显示:轮胎在制动状态下,胎面各花纹块沿滑动方向前端出现接触大变形。但由于整体轮胎模型胎面花纹部分网格较粗糙,计算得到的花纹块变形受力分布特征不够准确。为此,采用整体到局部的分析方法,建立采用精细网格的二维平面应变花纹块模型,由整体轮胎模型提供其简化边界条件,使用ABAQUS/explicit进行了滑动的热力耦合有限元分析。结果显示:采用精细网格的局部花纹块模型能反映出滑动前端卷曲大变形以及表面卷曲自接触的变形特征。最后,通过模拟ABS(防抱死制动系统)控制下轮胎胎面花纹块磨损过程,分析了胎面花纹块沿周向的不规则磨损特征。     

稳态滚动轮胎接地区域变形的模型分析

轮胎胎面的变形分析是轮胎力学的主要内容,也是轮胎结构设计、振动、噪声分析等和重要依据。本文利用轮胎的圆环－弹簧模型,给出了稳态滚动条件下轮胎的运动方程的简化形式。将轮胎分为接地区和非接地区两部分,视接地区为边界条件,采用一种简便的方法得到了轮胎变形的解析解,求出了接地区长度。     

橡胶复合材料结构非线性有限元分析

用非线性有限元法对一种典型的橡胶复合材料结构——轮胎的力学性能进行了分析。给出了轮胎滚动边界值问题的数学描述和有限元列式及相应的求解策略。取旋转刚体构形为参考构形, 得到消去时间变量的惯性场和控制方程。用增量约束方法处理轮胎滚动接触问题可以达到收敛快、精度高。研究了滚动参数对轮胎总体和局部变形和受力的影响。计算结果与已有数据和试验相吻合, 对轮胎设计和汽车动力学有指导意义。      

轮胎横向花纹沟噪声影响因素的剖析

运用Abaqus对具有横向花纹沟的轮胎滚动进行有限元分析,提取不同速度、气压、载荷、摩擦系数条件下的轮胎花纹沟表面在轮胎接地过程中位移-时间的变形曲线。为分析横向花纹沟的泵吸噪声,建立单个横向花纹沟及其周围的空气域有限元模型,在沟表面加载位移-时间变形曲线,利用FSI方法分析速度、气压、载荷、摩擦系数等使用因素对横向花纹沟泵吸噪声的影响。结果表明：泵吸噪声随着速度和载荷的增大而增大;气压变化均会使泵吸噪声增大;而摩擦系数对泵吸噪声影响不明显。验证FSI方法分析轮胎泵吸噪声是可行的,对后续低噪声轮胎使用和花纹设计具有一定的指导作用。     

乘用车子午线轮胎泵浦噪声机理的实验-数值混合分析方法

汽车在中高速行驶(乘用车超50 km/h,卡车超80 km/h)时,轮胎噪声取代其他部分噪声成为行驶噪声的主声源。轮胎噪声产生机理主要分为三种:泵浦噪声、振动噪声以及空气动力学噪声。其中泵浦噪声与轮胎花纹设计有关,属于可设计噪声。如何确定声源的频谱特性,进而预测轮胎噪声仍然是一个难点问题。提出一种泵浦噪声源识别的实验-数值混合分析方法。其基本的假设是:花纹横沟在进入地面和离开地面时产生气流,花纹纵沟将该气流收集,在轮胎接地前端和后端辐射出噪声;该噪声的大小与轮胎和地面形成的声场有关,也和轮胎花纹的节距排列有关。所提出的方法包括雕刻花纹轮胎噪声测试、轮胎声场阻抗数值分析、以及声源辨识三部分;通过在频域反演噪声传播过程辨识不同横沟的声源;通过雕刻花纹轮胎进行了噪声实验验证,说明了本方法的有效性。     

轮胎振动噪声的数值模拟

给出了一个可分析轮胎滚动时振动噪声的频域计算方法.该方法先利用有限元得到轮胎在地面滚动时表面节点的振动速度,并将其转化为声学计算的频域边界条件,再利用声学边界元计算轮胎的低频振动噪声.同时对该方法的有效性进行了考评,结果表明可以在400Hz以下的低频范围内分析轮胎的振动噪声特性.利用该方法,对215/55R16型轮胎的振动噪声进行了分析,初步揭示了该轮胎的振动噪声主要来自于轮胎的1阶侧向振动,2阶径向振动,3阶径向、侧向复合振动以及胎侧、胎面局部振动.其中2阶径向振动噪声和胎面局部振动噪声幅度较大且容易传入车内,影响乘坐舒适性,应该作为降低轮胎低频振动噪声的重点.还揭示了轮胎噪声声压幅值随着速度升高而迅速增大;随着充气压力和载荷的增减,轮胎刚度发生变化,从而导致振动噪声的改变,但变化幅值很小,且无明显规律.     

考虑滚动体滑移的全陶瓷角接触球轴承非线性动态特性分析

为了探究陶瓷滚动体发生滑移运动时全陶瓷角接触球轴承的动态特性,建立了滚动体与轴承外圈的接触模型,计算了滑移情况下的接触参数。在此基础上建立了考虑滚动体滑移行为的全陶瓷角接触球轴承动力学模型,通过模型的计算结果分析了轴承系统的振动特性和周期规律。由模型计算结果可知,滚动体发生滑移运动时接触变形和接触面积随载荷的增大而增大,然而接触变形远小于正常接触时的情况,接触面积大于正常接触时的情况。搭建了轴承转子试验台进行振动试验,在试验工况条件下得到的全陶瓷轴承振动幅值与模型计算的结果平均误差仅为0.68%,证明了模型的准确性。该研究为全陶瓷角接触球轴承的接触机理研究和动态特性分析提供了一定的理论依据。     

轮胎结构振动声学贡献度分析及降噪方法研究

以载重子午线轮胎295/80R22.5为研究对象,建立了其三维有限元分析模型,进行了有限元模态分析和试验模态测试,对比分析表明二者具有良好的一致性,说明所建有限元分析模型的正确性。为分析轮胎的振动噪声,建立了该子午线轮胎声学边界元模型。将滚动过程中轮胎与路面的作用力作为轮胎振动激励,运用模态声学传递向量MATV技术,分析了轮胎外轮廓结构对场点的声学贡献度,通过幅值-相位法确定胎面和胎侧是声学正贡献部件。为降低轮胎结构振动辐射噪声,在声学正贡献部件胎面和胎侧处引入聚氨酯类吸音材料,噪声分析结果表明,聚氨酯材料的使用能够有效地降低胎面和胎侧的振动加速度响应,降低轮胎的振动辐射噪声。     

基于时变接触刚度的球轴承双冲击现象动力学建模

剥落区长度与球轴承振动响应中的双冲击现象密切相关,传统方法对剥落区双冲击现象动力学机理建模都是基于恒定接触刚度,然而当球轴承滚道表面存在剥落时,滚动体与剥落区部分的接触区域不再为一椭圆面,滚动体与剥落区之间的接触不再满足接触刚度恒定这一条件。针对这一问题,以内圈滚道表面存在单一故障的球轴承为研究对象,基于Hertz接触理论,提出考虑滚动体与内圈剥落区之间时变接触刚度特性和时变位移激励的球轴承局部故障双冲击现象动力学机理模型,并对振动响应中的双冲击时间间隔进行分析。研究表明,该模型能克服传统的接触刚度计算方法未考虑滚动体与剥落区之间接触刚度时变性的缺点。通过仿真、实测及理论双冲击时间间隔对比,验证了该模型的有效性。     

家猫爪垫减振机理及其在轮胎花纹中的仿生应用研究

猫科动物运动时表现出极强的减振特性,爪垫作为与地面接触的唯一躯体部分是影响减振效果的关键因素.通过对家猫爪垫的组织学和接地力学试验研究表明,爪垫的减振机理主要体现在:爪垫组织结构呈现的多层特征有助于衰减接地应力;正常行走步态下爪垫力学特性表征出的爪垫-地接触中存在摆动变形的运动特征有利于缓冲储能的发挥.利用家猫爪垫的减...     

Finite element estimation of hysteretic loss and rolling resistance of 3-D patterned tire

Some of energy supplied to the vehicle driven on road is dissipated through rolling tires due to the hysteretic loss of rubber compounds, so the hysteretic loss is considered as a sort of pseudo-force resisting the tire rolling. This paper is concerned with the numerical prediction of the hysteretic loss and the rolling resistance (RR) of 3-D periodic patterned tire. A 3-D periodic patterned tire model is constructed by copying 1-sector tire mesh in the circumferential direction. Strain cycles during one revolution are approximated by utilizing the 3-D static tire contact analysis, for which the strain values at Gaussian points in the elements which are sector-wise repeated in the same circular ring of elements are taken. The strain amplitude during one revolution of tire is determined by taking the maximum principal value of the half amplitudes of each strain components in the multi-axial state of strain. The hysteretic loss during one revolution is predicted in terms of the loss modulus of rubber compound and the maximum principal value of the half amplitudes of six strain components. Through the numerical experiments, the validity of the proposed prediction method is examined by comparing with the experiment and the dependence of RR on the tread pattern is also investigated.     

Exploring new fields of virtual load prediction by accurate tire simulation for large deformations and flexible rim support

During the past ten years, there has been a significant trend in automotive design using low aspect ratio tires and increasingly run‐flat tires as well. In recent publications, the influence of those tire types on the dynamic loads – transferred from the road through the wheel into the car – have been examined pretty extensively, including comparative wheel force transducer measurements as well as computational results. It can be shown that the loads to the vehicle tend to increase when using low aspect ratio tires and particularly when using run‐flat tires. These tires provide higher stiffnesses while simultaneously introducing larger nonlinearities in the sidewall behavior [1–3]. Depending on manufacturer and the combination of vehicle size and wheel properties, these deformations can be so large that the tire belt and/or sidewall have contact with the rim crown (protected by the tire sidewall). The full vehicle simulation on virtual proving grounds is well established and important for the vehicle product development process. One of the most important subsystems in the virtual load assessment process, using full vehicle simulation is the tire model. The precision of that is essential for the overall accuracy of the virtual method. So the tendencies described above strongly require adaptations and improvements in the field of tire modeling. In 2007, Fraunhofer LBF together with Honda R&D started to examine the influences of low aspect ratio and run flat tires for the accuracy of full vehicle simulation results for durability relevant scenarios [3–5]. Those activities were the starting point for a four years joint activity to extend the usability of the virtual load prediction method by full vehicle simulation to application for which strong nonlinearities in the tire (large very transient deformation), but also in the vehicle model itself occur. As a part of that joint development, this paper summarizes the activities of Fraunhofer LBF to develop a dedicated tire model, which can accurately handle very large deformations of the tire up to misuse‐like applications. The model is based on the LBF tire model CDTire. In the first chapter several nonlinear extensions of the belt and sidewall model will be described which have been implemented to capture the large deformation behavior. These model extensions are also taking into account the belt‐to‐sidewall and sidewall‐to‐rim contact. To validate and to parameterize these model extensions, Fraunhofer LBF built a dedicated flat track test rig, which can be used to realize “roll‐over‐cleat” experiments using huge obstacles, so that belt‐to‐sidewall and sidewall‐to‐rim contact can be forced. This test rig will be described in chapter 2. The third chapter is dealing with the interface of the new tire model to a flexible rim. While the load transfer from road via tire into the vehicle is relatively easy to detect, for example by using wheel force transducers, the local forces acting on the rim flanges as well as on the wheel well (when e. g. passing a curb) are much more difficult to detect (in measurement as well as in simulation). LBF developed a method to detect local tire‐to‐rim interface forces and manage flexible rim simulation in Multi‐Body‐Simulation (LMS Virtual. Lab Motion – [6]). One key issue of the overall method is the capability of the tire model to predict local rim forces on the rim flanges in a suitable way. The second key issue is to combine the tire with a model of a flexible rim (which is embedded in a full vehicle MBS model). This method can be used to perform virtual load prediction of local, transient rim forces, which are the basis for CAE based fatigue life prediction of wheels applying typical durability test track and abuse load events.     

稳态滚动轮胎的有限元分析模型

建立了一个稳态滚动轮胎的有限元分析模型,考虑了轮胎变形的几何非线性、轮胎与地面和轮胎与轮辋的大变形非线性接触、轮胎材料的非均匀性、橡胶材料的不可压缩性和物理非线性、橡胶基复合材料的各向异性及轮胎与地面接触滑动摩擦。结果表明,该模型是较为合理的。      

A hierarchical sequential ALE poromechanics model for tire‐soil‐water interaction on fluid‐infiltrated roads

This paper introduces a hierarchical sequential arbitrary Lagrangian‐Eulerian (ALE) model for predicting the tire‐soil‐water interaction at finite deformations. Using the ALE framework, the interaction between a rolling pneumatic tire and the fluid‐infiltrated soil underneath will be captured numerically. The road is assumed to be a fully saturated two‐phase porous medium. The constitutive response of the tire and the solid skeleton of the porous medium is idealized as hyperelastic. Meanwhile, the interaction between tire, soil, and water will be simulated via a hierarchical operator‐split algorithm. A salient feature of the proposed framework is the steady state rolling framework. While the finite element mesh of the soil is fixed to a reference frame and moves with the tire, the solid and fluid constituents of the soil are flowing through the mesh in the ALE model according to the rolling speed of the tire. This treatment leads to an elegant and computationally efficient formulation to investigate the tire‐soil‐water interaction both close to the contact and in the far field. The presented ALE model for tire‐soil‐water interaction provides the essential basis for future applications, for example, to a path‐dependent frictional‐cohesive response of the consolidating soil and unsaturated soil, respectively. Copyright © 2017 John Wiley & Sons, Ltd.     

车辆-路面耦合振动系统模型与仿真分析

基于二分之一的四自由度车辆振动模型,把路面简化成Kelvin地基上Euler梁,通过非线性动态轮胎力,建立车路耦合系统的分析模型及其动力平衡方程;通过轮胎和路面的位移协调条件对耦合方程进行解耦,采用模态叠加法和New-mark积分法对耦合方程组进行求解。数值分析表明:轮胎作为参振子系统对路面的影响基本可以忽略不计,考虑轮胎作为参振子系统下车体的最大竖向位移是没有考虑情况下的1.2倍左右。并对车辆运动初速度、加速度、以及路面不平顺对车体振动影响进行了分析。     

Numerical analysis for dynamic contact between high‐speed wheel and elastic beam with Coulomb friction

For numerical analysis of the dynamic contact between a high‐speed wheel and an elastic beam, the equation of motion of each body is time integrated by a simple ODE solution technique and frictional contact conditions are imposed by the augmented Lagrange multiplier method using the contact errors defined in this work. For the stability of the numerical solution, the velocity and acceleration contact conditions as well as the displacement contact condition are imposed with special consideration for the high‐velocity contact point moving on the deformed beam. Especially, it is shown that the Coriolis and centripetal accelerations of the contact point moving rapidly on the deformed beam play crucial roles for the stability of the solution. It is also shown that, for a wheel rolling on a beam with friction, the acceleration constraint in the tangential direction is important for the stability of the solution. Copyright © 2008 John Wiley & Sons, Ltd.     

平面应变模具尺寸差对金属流变及其力能的影响

采用MARC/Superform有限元软件对平面应变压缩过程进行了二维有限元分析,分析了上下模具尺寸不相等时,对金属流变规律及其力能参数的影响.同时应用滑移线场理论对端部的滑移线场进行了分析,分析了金属的流动情况,进一步验证了有限元模拟结果的可靠性.研究结果显示:模具尺寸相等时,金属流动呈现对称分布;当上下两个模具尺寸不等时,金属流动呈现非对称分布,有剪切变形产生.而且随着模具尺寸差的增大,其交叉剪切变形越严重,总压力也增大,平均压力相对降低,这与异步轧制过程类似.所研究结果为异步轧制过程提供了一种新的物理模拟方法.