接地面部分溶化条件下冰面轮胎摩擦力的研究

综合运用流体动力润滑理论的能量守恒定律，提出了接地面部分溶化条件下冰面上汽车轮胎的摩擦力或牵引力的理论计算模型。证明了正常工作条件下，接地面上冰产生溶化的可能。对不同制动和驱动条件下轮胎摩擦力进行了计算，取得了同试验数据吻合很好的预测结果。并同已有预测模型进行了比较，比较结果表明：本文依据严格的润滑理论所推导出的冰面轮胎牵引力模型比其它已有理论模型更接近试验结果。     

接地面部分溶化条件下冰面轮胎摩托车的研究

综合运用流体动力润滑理论的能量守恒定律，提出了接地面部分溶化条件下冰面上汽车轮胎的摩擦力或牵引力的理论计算模型。证明了正常工作条件下，接地面上冰产生溶化的可能，对不同制动和驱动条件下轮胎摩托车进行了计算，取得了同试验数据吻合很好的预测结果，并同已有预测模型进行了比较，比较结果表明：本文依据严格的润滑理论所推导的冰面轮胎牵引力模型比其它已有理论模型更接近试验结果。     

接地面全熔化条件下冰面轮胎摩擦力的预测

依据流体动力润滑理论和热平衡原理，提出了接地面全熔化条件下冰面轮胎摩擦力的预测模型。结果表明，受不同因素的影响，摩擦系数变化趋势的模型预测同实验结果极为相似，文中分析讨论了影响摩擦力的主要因素，认杰表面模型，滑移率和界面温升等的影响应作为今后相关领域的研究重点。     

论轮胎与路面间的摩擦

对轮胎与路面间摩擦产生的机理和影响因素进行了分析。其中产生的机理可归纳为轮胎与路面间分子引力的作用、轮胎与路面间的粘着作用、胎面橡胶的弹性变形及路面上小尺寸微凸体的微切削作用四种；影响轮胎与路面间摩擦的主要因素有滑移率，轮胎类型，胎面花纹的类型、密度系数、深度，路面粗糙度，路面污染情况，路面水膜，气候及充气压力等。     

发动机拉缸原因及预防措施

拉缸的原理拉缸通常情况下是活塞和汽缸壁两个摩擦面间由于没有油膜存在而产生的一种局部金属熔化粘附现象。活塞、汽缸壁和活塞环的表面都具有一定的硬度和表面粗糙度,三者在一定的温度条件下相互配合工作,     

模具和板材的表面粗糙度对拉延摩擦特性的影响

探讨了拉延模具和成型板材的表面粗糙度对拉延工艺摩擦特性的影响。结果表明，在凹模圆角区，当使用固体润滑剂时，模具表面只有在粗糙度及波度小于润滑膜厚度，并且粗糙度分布垂直于板材滑动方向或为随机分布的条件下才是有利的，在一定条件下板材表面粗糙度的增大可减小摩擦系数，特别是润滑剂的粘度越大，冲压速度越高，这种效应则越明显。     

胎面单元对轮胎薄膜湿牵引性能的影响

在潮湿的天气或雨后，轮胎胎面或路面上存在一层很薄的水膜，该水膜使车辆行驶的牵引力降低。建立了轮胎胎面单元挤压膜问题的数学模型，并进行了数值求解，分析了胎面单元的几何参数，液膜厚度和柔性对轮胎薄膜湿牵引性能的影响，为轮胎胎面花纹的合理设计提供了理论依据。     

冬天车胎的选择﹕全天候轮胎

<正>全天候轮胎,与四季胎一样,给予我们方便,4条轮胎全年均可使用,不用入冬时换上去,天气热时换下来,省了麻烦及金钱。真正的全天候轮胎结合了夏季胎和冬季胎的优点,创新的胎面配方能够确保轮胎在四季不同的气候条件下均有较好的抓地和排水性能,并且具有良好的耐磨度。同时,胎面花纹的独特设计可以使轮胎自如应对干、湿、冰、雪等各种不同路况。专家指出,在我国中部和北部的大部分地区,冬夏季气候分明。消费者需     

汽车轮胎侧偏特性影响因素的试验研究

应用轮胎静力学特性试验机，研究了低速条件下3种不同胎面花纹轮胎在干燥路面上的侧偏特性，主要分析了胎面花纹、轮胎负荷和轮胎气压等因素对轮胎侧偏特性的影响。结果表明：轮胎的Fy-α关系曲线形状与胎面花纹形式、轮胎负荷和胎压等均无关。而Mz-α关系曲线变化趋势与胎面花纹无关，却与轮胎负荷和气压有关；在相同试验条件下，顺向花纹轮胎具有更优异的附着性能和侧偏特性。     

激光技术在摩托车上的应用（I）

激光技术在摩托车上的应用日益广泛，激光加工技术可用于托车零部件切削加工，焊接和打字；激光表面处理技术可用于摩托车零件表面的加热，熔化，蒸发及光化学处理；激光计量、检测技术可用于摩托车零件的粗糙度测量，气缸内孔的精密测量，活塞热变形的测量，复合材料零件和轮胎等内部的无损检测。     

冰雪路面摩擦系数的影响因素研究

冬季道路的表面通常覆盖着多层积雪,重交通量的路段积雪较薄,其厚度一般不足几厘米。积雪状态的变化直接影响着路面安全性,冰雪使路面变得非常湿滑,湿滑的路面条件由多种类型的积雪引起,本研究同时测量了冰面轮胎的静摩擦系数与动摩擦系数。     

考虑动压与路面粗糙度时轮胎湿牵引性能研究

根据流体动力润滑理论,将轮胎黏性滑水问题模拟为胎面单元与路面之间的动压、挤压膜问题,同时考虑了路面粗糙度的影响,建立了轮胎胎面单元黏性滑水问题的数学模型,并进行数值求解。以矩形胎面单元为例分析了胎面单元对轮胎黏性滑水性能的影响。结果表明,轮胎的薄膜湿牵引性能与滑动速度成反比;在考虑路面粗糙度的情况下,引入了膜厚比作为轮胎的薄膜湿牵引性能衡量标准,得出湿牵引性能与路面粗糙度成正比的结论。     

轮胎半经验模型中摩擦系数切换问题

介绍了2种简单的摩擦系数模型(库仑摩擦定律、静摩擦力模型)，并将其与轮胎统一刷子理论模型结合起来分析轮胎的摩擦问题。在此基础上引入了满足轮胎刷子理论模型边界条件的轮胎稳态半经验模型，给出了应用轮胎半经验模型实现摩擦状态切换的方法。通过轮胎在2种滚动速度下的侧偏试验，证明了轮胎半经验模型可实现2种速度下的摩擦系数切换。     

基于车路系统的事故现场轮胎印迹强度参数化研究

为明确事故现场可视轮胎印迹强度与车辆动力学特性、轮胎橡胶磨损特征及道路表面灰度之间的关联特性,提出基于车路耦合的事故现场轮胎印迹强度参数化研究方法。通过结合动态滑动摩擦因数模型及轮胎非线性模型,建立车辆路面9 DOF非线性系统动力学模型,运用VBOX惯性测量技术验证模型的有效性。运用胎面磨损能量模型,从车路系统角度确定车辆、轮胎和路面特性对轮胎全局摩擦力及胎面磨损特性的影响。结合印迹强度特征模型提出轮胎印迹强度参数研究方法,选取不同制动、转向角工况及3组路面、胎面特性对轮胎路面接地力学特性、胎面橡胶磨损量、可视轮胎印迹特征进行仿真分析。结果表明：印迹强度仅与全局摩擦力大小有关,与轮胎路面滑移方向无关;滑移工况下胎面橡胶磨损量随着全局摩擦力和滑移速度的增大而增大,而印迹强度变化不明显;制动力矩和道路表面灰度对产生可视轮胎印迹起决定作用,转向角主要影响不规则可视轮胎印迹的产生;前轮轮胎最先出现可视印迹,且可视印迹长度和强度均高于后轮轮胎;采取可视印迹起点作为事故车辆速度判定具有一定的误差,应根据具体情况进行具体分析;研究成果能够为基于可视轮胎印迹的交通事故重建提供理论基础。     

Dynamic Friction Models for Road/Tire Longitudinal Interaction

Summary In this paper we derive a new dynamic friction force model for the longitudinal road/tire interaction for wheeled ground vehicles. The model is based on a dynamic friction model developed previously for contact-point friction problems, called the LuGre model. By assuming a contact patch between the tire and the ground we develop a partial differential equation for the distribution of the friction force along the patch. An ordinary differential equation (the lumped model) for the friction force is developed, based on the patch boundary conditions and the normal force distribution along the contact patch. This lumped model is derived to approximate closely the distributed friction model. Contrary to common static friction/slip maps, it is shown that this new dynamic friction model is able to capture accurately the transient behaviour of the friction force observed during transitions between braking and acceleration. A velocity-dependent, steady-state expression of the friction force versus the slip coefficient is also developed that allows easy tuning of the model parameters by comparison with steady-state experimental data. Experimental results validate the accuracy of the new tire friction model in predicting the friction force during transient vehicle motion. It is expected that this new model will be very helpful for tire friction modeling as well as for anti-lock braking (ABS) and traction control design.     

Analytical dynamic tire model

Modeling of tire friction is one of the central problems for vehicle control systems design. LuGre-type dynamic tire model has been proposed and well discussed in previous studies, because it offers a compact form of dynamic model that is convenient in advanced control studies. It has been successfully used in tire slip control design and vehicle state estimation problems. In this article, a concept of time-constrained Stribeck effect is introduced to interpret the mechanism of the LuGre friction model in predicting tire friction characteristics. A modified two-dimensional (2D) dynamic LuGre friction model is introduced to make it compatible with the governing theorem in the steady state. An analytical 2D modified LuGre-type dynamic tire model is developed, in which some fundamental limitations of classical LuGre models are eliminated. The main modifications involve a change in the structure of the 2D LuGre friction model, introduction of load-dependent parameters in 1D and 2D tire models, and a changed structure in the distributed parameter model. The proposed model is compared, in the steady state, to both the Magic Formula and the classical LuGre model. It improves model accuracy in the steady state and gives a physically reasonable distribution of the bristle deflection. A first-order lumped parameter (LP) nonlinear model, which has simpler structure than the distributed parameter model and the classical LP LuGre model, is then derived. Numerical simulations show that the proposed LP model has a good estimation for tire transient dynamics. Thus, the proposed model retains the merits of LuGre-type models and improves the agreement with observation and experimental data on friction force distribution along the patch and on the steady-state friction prediction.     

Vehicle Energy Dissipation Due to Road Roughness

Road roughness and surface texture are known to affect tire rolling resistance; however, little emphasis has been placed on the consequent changes in total vehicle energy dissipation due to road roughness. Thus, tire rolling resistance, in isolation from vehicle contributed losses such as dissipation in the suspension, appears to be a weakness in present evaluation procedures as they relate to fuel economy and pollution level testing: Recent work by Funfsinn and Korst has shown that substantial and measurable increases in energy losses occur for vehicles traveling on rough roads. The present investigation uses vehicle axle accelerations as a means of examining various road surfaces. Correlation with computer simulations has allowed the development of a deterministic road roughness model which permits the prediction of energy dissipation in both the tire and suspension as functions of road roughness, tire pressure, and vehicle speed. Comparison to the experiments of Korst and Funfsinn results in good agreement and shows that total rolling loss increases of up to 20 percent compared to ideal smooth roads are possible. The aerodynamic drag coefficient is also found to increase while driving on rough roads.     

Vehicle Energy Dissipation Due to Road Roughness

SUMMARY

Road roughness and surface texture are known to affect tire rolling resistance; however, little emphasis has been placed on the consequent changes in total vehicle energy dissipation due to road roughness. Thus, tire rolling resistance, in isolation from vehicle contributed losses such as dissipation in the suspension, appears to be a weakness in present evaluation procedures as they relate to fuel economy and pollution level testing: Recent work by Funfsinn and Korst has shown that substantial and measurable increases in energy losses occur for vehicles traveling on rough roads. The present investigation uses vehicle axle accelerations as a means of examining various road surfaces. Correlation with computer simulations has allowed the development of a deterministic road roughness model which permits the prediction of energy dissipation in both the tire and suspension as functions of road roughness, tire pressure, and vehicle speed. Comparison to the experiments of Korst and Funfsinn results in good agreement and shows that total rolling loss increases of up to 20 percent compared to ideal smooth roads are possible. The aerodynamic drag coefficient is also found to increase while driving on rough roads.     

Dynamic Friction Models for Road/Tire Longitudinal Interaction

Summary In this paper we derive a new dynamic friction force model for the longitudinal road/tire interaction for wheeled ground vehicles. The model is based on a dynamic friction model developed previously for contact-point friction problems, called the LuGre model. By assuming a contact patch between the tire and the ground we develop a partial differential equation for the distribution of the friction force along the patch. An ordinary differential equation (the lumped model) for the friction force is developed, based on the patch boundary conditions and the normal force distribution along the contact patch. This lumped model is derived to approximate closely the distributed friction model. Contrary to common static friction/slip maps, it is shown that this new dynamic friction model is able to capture accurately the transient behaviour of the friction force observed during transitions between braking and acceleration. A velocity-dependent, steady-state expression of the friction force versus the slip coefficient is also developed that allows easy tuning of the model parameters by comparison with steady-state experimental data. Experimental results validate the accuracy of the new tire friction model in predicting the friction force during transient vehicle motion. It is expected that this new model will be very helpful for tire friction modeling as well as for anti-lock braking (ABS) and traction control design.