Predictive modelling of volumetric and Marshall properties of asphalt mixtures modified with waste tire-derived char:A statistical neural network approach

The goals of this study are to assess the viability of waste tire-derived char(WTDC)as a sustainable,low-cost fine aggregate surrogate material for asphalt mixtures and to develop the statistically coupled neural network(SCNN)model for predicting volumetric and Marshall properties of asphalt mixtures modified with WTDC.The study is based on experimental data acquired from laboratory volumetric and Marshall properties testing on WTDCmodified asphalt mixtures(WTDC-MAM).The input variables comprised waste tire char content and asphalt binder content.The output variables comprised mixture unit weight,total voids,voids filled with asphalt,Marshall stability,and flow.Statistical coupled neural networks were utilized to predict the volumetric and Marshall properties of asphalt mixtures.For predictive modeling,the SCNN model is employed,incorporating a three-layer neural network and preprocessing techniques to enhance accuracy and reliability.The optimal network architecture,using the collected dataset,was a 2:6:5 structure,and the neural network was trained with 60%of the data,whereas the other 20%was used for cross-validation and testing respectively.The network employed a hyperbolic tangent(tanh)activation function and a feed-forward backpropagation.According to the results,the network model could accurately predict the volumetric and Marshall properties.The predicted accuracy of SCNN was found to be as high value>98%and low prediction errors for both volumetric and Marshall properties.This study demonstrates WTDC's potential as a low-cost,sustainable aggregate replacement.The SCNN-based predictive model proves its efficiency and versatility and promotes sustainable practices.

Development and Validation of a Scaled Electric Combat Vehicle Tire Model

Pneumatic tire modeling and validation have been the topic of several research papers, however, most of these papers only deal with pneumatic passenger and truck tires. In recent years, wheeled-scaled vehicles have gained lots of attention as a feasible testing platform, nonetheless up to the authors’ knowledge there has been no research regarding the use of scaled tires and their effect on the overall vehicle performance characteristics. This paper presents a novel scaled electric combat vehicle tire model and validation technique. The pro-line lockdown tire size 3.00 × 7.35 is modeled using the Finite Element Analysis (FEA) technique and several materials including layered membrane, beam elements, and Mooney-Rivlin for rubber. The tire-rim assembly is then described, and the rigid body analysis is presented. The tire is then validated using an in-house custom-made static tire testing machine. The tire test rig is made specifically to test the pro-line tire model and is designed and manufactured in the laboratory. The tire is validated using vertical stiffness and footprint tests in the static domain at different operating conditions including several vertical loads. Then the tire is used to perform rolling resistance and steering analysis including the rolling resistance coefficient and the cornering stiffness. The analysis is performed at different operating conditions including longitudinal speeds of 5, 10, and 15 km/h. This tire model will be further used to determine the tractive and braking performance of the tire. Furthermore, the tire test rig will also be modified to perform cornering stiffness tests.

UniTire轮胎稳态模型的速度预测能力

为了降低轮胎高速试验的条件限制与成本,通过利用TNO不同速度下的侧偏试验数据,研究了统一轮胎模型UniTire从低速试验数据预测高速轮胎力学特性的能力。其中包括速度对动摩擦系数的影响;速度对侧偏和纵滑刚度的影响;速度对气胎拖距的影响。试验结果证明了UniTire轮胎模型在从低速轮胎试验预测高速轮胎力学特性方面具有很高的预测精度。

UniTire轮胎稳态模型的联合工况预测能力研究

通过少量的标准试验得到轮胎力学特性参数,可以预测联合工况下(纵滑、侧偏、侧倾)的力学特性,这样就能避免做大量的复合试验。通过对轮胎简化理论模型的简单介绍,提出满足高阶理论边界条件的统一轮胎模型Un iTire,并对动摩擦因数和总切力方向修正系数给予说明。通过轮胎试验数据,使用不同辨识方法验证其预测能力,证明Un iTire轮胎稳态模型具有很高的预测精度。

UniTire统一轮胎模型

UniTire模型是用于车辆动力学仿真和控制的非线性非稳态轮胎模型,能够准确描述轮胎在复杂工况下的力学特性。UniTire模型以理论模型为基础,采用无量纲的表达形式,具有统一的滑移率定义;统一的无量纲印迹压力分布表达;统一的各向轮胎力无量纲建模;统一的各向摩擦系数表达;无量纲边界条件的统一满足;不同速度下轮胎模型的统一表达;稳态与非稳态特性的统一;侧倾、转偏作用与侧偏特性的统一。不仅能够对各种工况下的轮胎力学特性进行高精度的表达,还具有良好的外推能力和预测能力,能够对复合工况、不同路面和不同速度下的轮胎特性进行准确的预测。本研究围绕UniTire的建模思想,介绍UniTire建模的理论基础、稳态和非稳态模型以及模型的表达和预测能力并进行试验验证。

基于UniTire模型的平顺性和操纵稳定性协同研究

为考虑平顺性和操纵稳定性两者之间的联系和相互影响,本文中对两者进行了协同研究。首先基于UniTire模型,结合前后轮路面激励的滤波白噪声模型、平顺性4自由度平面模型和操纵稳定性2自由度平面模型,采用状态方程构建了平顺性和操纵稳定性的协同模型,提出了协同仿真算法。然后在常用路面等级和车速下,对某轿车进行了平顺性和操纵稳定性协同仿真。结果表明,采用平顺性和操纵稳定性协同模型,可同时实现两个性能的协同仿真,而由线性UniTire模型仿真得到的操纵稳定性参数大于非线性UniTire模型仿真的对应结果,说明采用线性轮胎模型研究操纵稳定性偏于保守。

基于UniTire侧向力模型的汽车操纵稳定性的建模和仿真

为了进行汽车操纵稳定性建模和仿真,总结了非线性和线性Uni Ttire侧向力模型。基于平面假设,建立了考虑轮胎非线性和线性的汽车操纵稳定性二自由度模型,提出了基于线性和非线性Uni Ttire侧向力模型的操纵稳定性仿真算法。在常用车速60 km/h下,对某轿车操纵稳定性进行了仿真,获得了横摆角速度、质心侧偏角和侧向加速度的时间历程。研究结果表明,基于线性和非线性Uni Ttire侧向力模型仿真的横摆角速度、质心侧偏角和侧向加速度是不同的,研究汽车操纵稳定性应关注轮胎的非线性。

UniTire与Magic Formula稳态模型的对比研究

荷兰学者Pacejka提出的魔术公式Magic Formula和我国郭孔辉教授提出的统一轮胎模型UniTire在汽车操纵动力学研究中得到了广泛的应用。通过对这两种模型建模机理的对比表明,UniTire轮胎模型比MagicFor-mula模型具有更强的理论基础;通过试验数据辨识模型参数对比两种模型的全局辨识精度以及预测精度的结果表明,UniTire轮胎模型的全局辨识精度略高于Magic Formula模型,而且明显具有更高的预测能力。

大侧倾角下UniTire稳态侧倾侧偏工况侧向力模型

大侧倾角下,轮胎侧偏力学特性仅仅采用等效侧偏角的方法不能进行准确描述,还需要考虑侧倾对其他关键参数的影响。基于简单刷子模型,建立轮胎稳态侧倾侧偏工况侧向力物理模型,导出用于半经验建模的理论边界条件。采用定性分析及试验观察相结合的方法分析侧倾对侧偏刚度和摩擦因数的影响,并建立相应的半经验模型。根据理论边界条件,分析侧倾对UniTire稳态侧向力模型中曲率因子的影响,并提出新的曲率因子表达式。通过轮胎试验数据进行参数辨识,结果表明所建立的UniTire稳态侧向力模型具有很高的精度,并且能够表达大侧倾角下轮胎的力学特性。

基于UniTire轮胎模型的汽车行驶速度估计

准确而实时地获取车速信息是汽车实现高精度定位与导航、高级巡航控制和编队巡航控制等功能的必要前提,文中提出一种基于UniTire轮胎模型的汽车行驶速度估计方法。首先,基于UniTire轮胎模型建立包含汽车纵向、侧向和横摆动态的车速估计名义模型,并利用自适应遗传算法的全局搜索优势和拟牛顿法的局部搜索优势辨识出UniTire轮胎模型的特征参数的全局最优解;随后,以车速估计名义模型的过程噪声和观测噪声为调度变量,利用强跟踪中心差分卡尔曼滤波器设计一簇车速估计器,并采用交互式多模型算法对基于强跟踪中心差分卡尔曼滤波器的车速估计器簇的输出结果进行平滑融合;最后,利用整车级硬件在环仿真平台对所提出的基于交互式强跟踪中心差分卡尔曼滤波器的车速估计算法的可行性和有效性进行验证。结果表明:相对于基于强跟踪中心差分卡尔曼滤波器的车速信息估计算法,本文提出的车速信息估计算法对系统噪声统计特性具有更好的自适应能力,并且具有更高的估计精度。

Finite Element Simulation of Radial Tire Building and Shaping Processes Using an Elasto-Viscoplastic Model

The comprehensive tire building and shaping processes are investigated through the finite element method(FEM)in this article.The mechanical properties of the uncured rubber from different tire components are investigated through cyclic loading-unloading experiments under different strain rates.Based on the experiments,an elastoviscoplastic constitutive model is adopted to describe themechanical behaviors of the uncured rubber.The distinct mechanical properties,including the stress level,hysteresis and residual strain,of the uncured rubber can all be well characterized.The whole tire building process(including component winding,rubber bladder inflation,component stitching and carcass band folding-back)and the shaping process are simulated using this constitutive model.The simulated green tire profile is in good agreement with the actual profile obtained through 3D scanning.The deformation and stress of the rubber components and the cord reinforcements during production can be obtained fromthe FE simulation,which is helpful for judging the rationality of the tire construction design.Finally,the influence of the parameter“drum width”is investigated,and the simulated result is found to be consistent with the experimental observations,which verifies the effectiveness of the simulation.The established simulation strategy provides some guiding significance for the improvement of tire design parameters and the elimination of tire production defects.

基于混合优化方法的UniTire轮胎模型参数辨识

提出一种基于粒子群优化(PSO)算法和修正的Gauss-Newton算法的混合优化方法,对纯纵滑和纯侧偏工况下UniTire轮胎模型的特征参数进行辨识。为充分发挥两个算法的优点,首先,利用粒子群优化算法的全局区域的搜索优势辨识出UniTire轮胎模型的特征参数近似解,然后,利用修正的Gauss-Newton算法局部搜索优势在近似解邻近区域获得UniTire轮胎模型的特征参数的最优解。最后,对辨识结果进行残差分析,结果表明:用辨识数据参数化的UniTire轮胎模型具有较高的精度,可满足构建车辆底盘电控系统硬件在环仿真测试环境的需求。

FEM tire model oriented to virtual experiment of off-road vehicle trafficability

In order to estimate the trafficability of off-road vehicles, the linear relationships between the pressure and the stiffness of the tire and the action of the vertical tire force with the viscoelasticity are analyzed. The method to improve the precision of the model by the coefficients is presented. The constitutive equation of the three-parameter linear model and the stiffness matrix of four-node isoparametric elements are derived to construct the FEM （finite element method） tire model in plan stress. A demarcation and verification system is designed based on the six-dimensional wheel force transducer and the vertical tire force is measured under different velocities. The results show that the model and the method proposed are reasonable.

Mathematical Models of Tire-Longitudinal Road Adhesion and Their Use in the Study of Road Vehicle Dynamics

Mathematical models of tire-longitudinal road adhesion for use in the study of road vehicle dynamics are set up so as to express the relations of longitudinal adhesion coefficients with the slip ratio. They perfect the Pacejka's models in practical use by taking into account the influences of all essential parameters such as road surface condition. vehicle velocity. slip angle. vertical load and slip ratio on the longitudinal adhesion coefficients. The new models are more comprehensive more concise. simpler and more convenient in application in all kinds of simulations of car dynamics in various sorts of braking modes.

An Adaptive Nonsingular Fast Terminal Sliding Mode Control for Yaw Stability Control of Bus Based on STI Tire Model

Due to the bus characteristics of large quality,high center of gravity and narrow wheelbase,the research of its yaw stability control(YSC)system has become the focus in the field of vehicle system dynamics.However,the tire nonlinear mechanical properties and the effectiveness of the YSC control system are not considered carefully in the current research.In this paper,a novel adaptive nonsingular fast terminal sliding mode(ANFTSM)control scheme for YSC is proposed to improve the bus curve driving stability and safety on slippery roads.Firstly,the STI(Systems Technologies Inc.)tire model,which can effectively reflect the nonlinear coupling relationship between the tire longitudinal force and lateral force,is established based on experimental data and firstly adopted in the bus YSC system design.On this basis,a more accurate bus lateral dynamics model is built and a novel YSC strategy based on ANFTSM,which has the merits of fast transient response,finite time convergence and high robustness against uncertainties and external disturbances,is designed.Thirdly,to solve the optimal allocation problem of the tire forces,whose objective is to achieve the desired direct yaw moment through the effective distribution of the brake force of each tire,the robust least-squares allocation method is adopted.To verify the feasibility,effectiveness and practicality of the proposed bus YSC approach,the TruckSim-Simulink co-simulation results are finally provided.The co-simulation results show that the lateral stability of bus under special driving conditions has been significantly improved.This research proposes a more effective design method for bus YSC system based on a more accurate tire model.

Tire Dynamics Modeling Method Based on Rapid Test Method

Combined with the tire dynamics theoretical model,a rapid test method to obtain tire lateral and longitudinal both steady-state and transient characteristics only based on the tire quasi-steady-state test results is proposed.For steady state data extraction,the test time of the rapid test method is half that of the conventional test method.For transient tire characteristics the rapid test method omits the traditional tire test totally.At the mean time the accuracy of the two method is much closed.The rapid test method is explained theoretically and the test process is designed.The key parameters of tire are extracted and the comparison is made between rapid test and traditional test method.The result show that the identification accuracy based on the rapid test method is almost equal to the accuracy of the conventional one.Then,the heat generated during the rapid test method and that generated during the conventional test are calculated separately.The comparison shows that the heat generated during the rapid test is much smaller than the heat generated during the conventional test process.This benefits to the reduction of tire wear and the consistency of test results.Finally,it can be concluded that the fast test method can efficiently,accurately and energy-efficiently measure the steady-state and transient characteristics of the tire.

Effect of Tire Repeated Root Modal on Tire Modelling with Experimental Modal

The effect of tire repeated root modal（RRM）on tire modeling with an experimental modal is studied.Firstly,a radial tire with radial and tangential RRMs is tested and analyzed.By multi-point exciting of the radial tire,a multiple reference frequency domain method based on a least squares（LMS PolyMAX）algorithm is used to identify modal parameters.Then,modal stability diagram（MSD）,modal indication function（MIF）and modal assurance criteria（Auto-MAC）matrix are utilized to induce multiple inputs multiple outputs（MIMO）frequency response function（FRF）matrixes.The tests reveal that notable repeated roots exist in both radial and tangential response modes.Their modal frequencies and damping factors are approximately the same,the amplitudes of modal vectors are in the same order of magnitude,and the mode shapes are orthogonal.Based on the works mentioned,the method of trigonometric series modal shapes fitting is adopted,the effects of RRM model on tire modeling with a vertical experimental modal are discussed.The final results show that the effects of considering the RRM shapes are equivalent to the tire mode shapes depended on rotating the tire’s different exciting points during tire modeling,and since considering the RRM,the tire mode shapes can be unified and fixed during tire modeling.

Finite Element Analysis of Tire Traction Using a Rubber-Ice Friction Model

The friction of road surface covered by snow or ice is very low and that results in reducing vehicle traction forces and potential traffic accidents. In general, to establish a master curve on a rubber-ice friction model is difficult because the ice surface, being not far removed from its melting point, reacts itself very sen-sitively to pressure, speed, and temperature changes. In this paper, an accepta-ble frictional interaction model was implemented to finite element method to rationally examine the frictional interaction behavior on ice between the tire and the road surface. The formula of friction characteristic according to tem-perature and sliding velocity on the ice surface was applied for tire traction analysis. Numerical results were verified by comparing the outdoor test data and it was confirmed to indicate similar correlation. It is found that the rub-ber-ice friction model will be useful for the improvement of the ice traction performance of tire.

用于轮胎振动分析的壳模型优化研究

虽然现有壳模型在0~500 Hz频带内精度高,适合用于轮胎结构振动分析,但由于模型中耦合了胎侧二维壳模型,导致胎冠振动模态难以分离,且模型自由度和所需输入参数增加。本文对该壳模型进行改进:在保持胎冠壳模型不变的基础上,应用轮胎环模型和板模型中对胎侧的近似方法,采用弹性基底代替胎侧二维壳模型,简化了原模型的边界条件并缩减了输入参数个数;针对改进后的壳模型建立了求解方法,实现了胎冠模态频率和振型的求解。并通过与实验数据的对比,验证了改进后的壳模型及其求解方法的正确性。

基于自主漂移的自动驾驶车辆极限工况轨迹规划与控制

为兼顾自动驾驶车辆在极限工况下的稳定性与轨迹跟踪性能,提出了一种基于自主漂移的自动驾驶车辆轨迹规划与控制方法。基于神经网络设计了神经网络轮胎动力学模型,提升了传统魔术轮胎公式的精度。为进一步拓展自动驾驶车辆极限工况下的稳定边界,基于漂移时轮胎饱和及最大侧滑特性结合质心侧偏角-横摆角速度相平面约束设计了漂移稳定边界,采用非线性模型预测控制(NMPC)在更大稳定范围内规划了安全漂移轨迹,并对规划轨迹进行了漂移跟踪控制。Simulink/CarSim联合仿真结果表明,该方法可充分利用漂移运动优势,在极限工况下确保车辆不发生失控,同时准确跟踪期望轨迹。