Mechanical properties and damage evolution characteristics of waste tire steel fiber-modified cemented paste backfill

During the process of constructional backfill mining,the cemented paste backfill(CPB)typically exhibits a high degree of brittleness and limited resistance to failure.In this study,the mechanical and damage evolution characteristics of waste tire steel fiber(WTSF)-modified CPB were studied through uniaxial compression tests,acoustic emission(AE)tests,and scanning electron microscopy(SEM).The results showed that the uniaxial compressive strength(UCS)decreased when the WTSF content was 0.5%,1%,and 1.5%.When the WTSF content reached 1%,the UCS of the modified CPB exhibited a minimal decrease(0.37 MPa)compared to that without WTSF.When the WTSF content was 0.5%,1%,and 1.5%,peak strain of the WTSF-modified CPB increased by 18%,31.33%,and 81.33%,while the elastic modulus decreased by 21.31%,26.21%,and 45.42%,respectively.The addition of WTSF enhances the activity of AE events in the modified CPB,resulting in a slower progression of the entire failure process.After the failure,the modified CPB retained a certain level of load-bearing capacity.Generally,the failure of the CPB was dominated by tensile cracks.After the addition of WTSF,a gradual increase in the proportion of tensile cracks was observed upon loading the modified CPB sample to the pore compaction stage.The three-dimensional localization of AE events showed that the WTSF-modified CPB underwent progressive damage during the loading,and the samples still showed good integrity after failure.Additionally,the response relationship between energy evolution and damage development of WTSF-modified CPB during uniaxial compression was analyzed,and the damage constitutive model of CPB samples with different WTSF contents was constructed.This study provides a theoretical basis for the enhancement of CPB modified by adding WTSF,serving as a valuable reference for the design of CPB constructional backfill.

Simulation and Experimental Study on Load-bearing Deformation Characteristics of 11R22.5 Vehicle Retreaded Tire

The finite element bearing deformation simulation was implemented on 11.00R22.5 retreaded tires by ANSYS software in the paper in order to further clarify the bearing deformation characteristics of retreaded tires and improve the performance of retreaded tires effectively.The characteristic laws of bearing radial deformation and bearing lateral deformation of retreaded tire and new tires of the same model under different working conditions were obtained through load deformation tests.The radial deformation calculation results,simulation results and measured results of retreaded tires were comparatively analyzed.The calculation formula of bearing radial deformation of retreaded tires was proposed based on the linear regression principle.The difference of bearing deformation characteristics and ground area characteristics of retreaded tires and new tires were comparatively analyzed.The results showed that the radial and lateral deformation of retreaded tires and new tires is increased with the increase of radial load when the tire pressure was constant,and the increase trend is approximately linear.The radial stiffness of retreaded tires is similar to that of new tires under certain tire pressure and low load.The radial stiffness of retreaded tires is larger than that of new tires,and the stiffness difference is increased with the increasing of load under constant tire pressure and high load.Rubber aging phenomenon in retreaded tire carcass have an impact on the bearing deformation characteristics of retreaded tires,thereby producing great impact on the remaining service life of retreaded tires.

Non-pneumatic mechanical elastic wheel natural dynamic characteristics and influencing factors

Non-pneumatic tire appears to have advantages over traditional pneumatic tire in terms of flat proof and maintenance free.A mechanical elastic wheel(MEW) with a non-pneumatic elastic outer ring which functions as air of pneumatic tire was presented.The structure of MEW was non-inflatable integrated configuration and the effect of hinges was accounted for only in tension. To establish finite element model of MEW, various nonlinear factors, such as geometrical nonlinearity, material nonlinearity and contact nonlinearity, were considered. Load characteristic test was conducted by tyre dynamic test-bed to obtain force-deflection curve. And the finite element model was validated through load characteristic test. Natural dynamic characteristics of the MEW and its influencing factors were investigated based on the finite element model. Simulation results show that the finite element model closely matched experimental wheel. The results also show that natural frequency is related to ground constraints, material properties, loads and torques. Influencing factors as above obviously affect the amplitude of mode of vibration, but have little effect on mode of vibration shape. The results can provide guidance for experiment research, structural optimization of MEW.

Influence of Tire Dynamics on Slip Ratio Estimation of Independent Driving Wheel System

The independent driving wheel system, which is composed of in-wheel permanent magnet synchronous motor（I-PMSM） and tire, is more convenient to estimate the slip ratio because the rotary speed of the rotor can be accurately measured. However, the ring speed of the tire ring doesn’t equal to the rotor speed considering the tire deformation. For this reason, a deformable tire and a detailed I-PMSM are modeled by using Matlab/Simulink. Moreover, the tire/road contact interface（a slippery road） is accurately described by the non-linear relaxation length-based model and the Magic Formula pragmatic model. Based on the relatively accurate model, the error of slip ratio estimated by the rotor rotary speed is analyzed in both time and frequency domains when a quarter car is started by the I-PMSM with a definite target torque input curve. In addition, the natural frequencies（NFs） of the driving wheel system with variable parameters are illustrated to present the relationship between the slip ratio estimation error and the NF. According to this relationship, a low-pass filter, whose cut-off frequency corresponds to the NF, is proposed to eliminate the error in the estimated slip ratio. The analysis, concerning the effect of the driving wheel parameters and road conditions on slip ratio estimation, shows that the peak estimation error can be reduced up to 75% when the LPF is adopted. The robustness and effectiveness of the LPF are therefore validated. This paper builds up the deformable tire model and the detailed I-PMSM models, and analyzes the effect of the driving wheel parameters and road conditions on slip ratio estimation.

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.

非充气轮胎的滚动越障振动仿真分析

采用仿真分析方法探究非充气轮胎的滚动越障振动特性。建立非充气轮胎的有限元模型,对辐条式原始非充气轮胎(简称原始轮胎)和轮辐仿生优化非充气轮胎(简称优化轮胎)的滚动越障振动进行仿真分析,研究滚动速度和障碍物高度对原始轮胎和优化轮胎的径向和纵向振动的影响,以及两种轮胎的振动特性与其滚动越障时接地压力峰值标准差之间的关系。结果表明:越障时滚动速度和障碍物高度的增大会加剧非充气轮胎的径向和纵向振动;与原始轮胎相比,优化轮胎的减振效果主要体现在滚动速度和障碍物高度变化时其振动特性较为平稳;接地压力峰值标准差能够在一定程度上表征非充气轮胎的振动强度。非充气轮胎的滚动越障振动仿真分析为其动态特性研究奠定了一定的理论基础,对提高车辆的稳定性具有重要的意义。

轻型汽车轮胎磨损颗粒物排放特征及影响因素

为探明轮胎磨损颗粒物(TWPs)的排放特征,针对典型轻型汽车开展了基于实际道路行驶的轮胎磨损排放测试,系统分析了TWPs的理化特征及受环境温度、车辆类型、机动车整备质量和轮胎位置等因素的影响.结果表明:TWPs主要金属元素有Si、Ca和Na等,尺寸集中于5~30μm,外观呈球形、棒状、团聚及不规则等多种形状,OC/EC平均值为4.8;秋冬季TWPs平均排放因子(112.7mg/km)略高于春夏季(104.6mg/km);汽车整备质量与TWPs排放因子呈一定正相关性;电动汽车TWPs排放因子(70.2~177.6mg/km)略高于燃油汽车(54.2~155.2mg/km);轻型汽车前胎TWPs排放量平均高于后胎6%~30%;经测算,2022年全国轻型汽车TWPs年排放总量达48.1万t,高于尾气细颗粒物排放.

基于PSO-BP神经网络的轮胎负荷测量方法

研究基于粒子群优化(PSO)算法-BP神经网络的轮胎负荷测量方法。将采集的轮胎状态信息与提取到的加速度特征输入到BP神经网络,对轮胎负荷进行回归预测,使用PSO算法优化BP神经网络的权值与阈值,得到轮胎状态信息与轮胎负荷的关系。结果表明,采用PSO-BP神经网络预测轮胎负荷误差为1.8656%,PSO-BP神经网络预测精度较高,在转变工况条件下,预测误差为2.496%。

湿滑状态下飞机轮胎与道面摩擦特性试验

湿滑道面会造成飞机制动性能下降,影响起降安全。通过搭建污染跑道摩擦特性测试装置,根据飞机在湿滑道面滑跑的实际情况,对飞机轮胎在不同水膜厚度、速度、载荷条件下运行的接触力、滑移距离进行研究,分析了湿滑条件下道面摩擦特性与影响因素间的关系。实验结果表明:水膜厚度对道面摩擦特性影响显著,水膜厚度为13 mm时,轮胎与道面之间的接触应力变化明显,滑移距离大幅度增加。随着速度的增加,轮胎与道面之间的接触应力呈线性增加趋势,过高的速度会增加滑水风险。轮胎载荷的增加会减少湿滑道面上的滑移距离,在一定程度上提高飞机轮胎的载荷,能有效改善湿滑道面上的摩擦特性。

胎压差影响下车辆并装双胎滑水特性教学仿真

载货车辆并装双胎滑水实验极具危险性,在高校车辆类专业教学中难以开展,且胎压差影响下的滑水机理至今尚未探明。针对该问题,基于流固耦合原理,建立车辆并装双胎-积水-路面流固耦合模型并验证有效性,探明胎压差对滑水动力学行为的影响机理,揭示不同胎压差下双胎运动状态、水膜厚度对双胎滑水特性的影响规律。结果表明:并装双胎滑水时双胎间隙存有大量积水,积水高度远超水膜厚度;并装双胎自由滚动状态时胎压差增加,滑水性能降低;相同胎压差下,防抱死制动系统(anti-lock braking system,ABS)控制状态较自由滚动状态更易发生滑水;水流竖向托举力随胎压差和水膜厚度的增大而增大。该研究可用于指导并装双胎车辆设计和使用,进一步提高湿滑路面上车辆行驶安全性,也为轮胎滑水动力学教学仿真与实验提供参考。

航空轮胎胎面胶等效工况磨损特性研究

使用自主研制的航空轮胎等效摩擦磨损试验平台对航空轮胎不同服役工况下的摩擦行为进行等效拆解,研究加载条件对加速起飞、着陆瞬间和制动滑行摩擦工况对胎面胶磨损特性的影响。结果表明:3种工况中,制动滑行是航空轮胎胎面胶快速磨损的主要工况,制动滑行工况下胎面胶磨损率明显大于加速起飞和着陆瞬间工况下;等效摩擦磨损试验平台可实现航空轮胎胎面胶摩擦行为的模拟,可作为高耐磨胎面胶配方开发的评价工具。

飞机轮载作用下土质道面轮辙特征仿真分析

本文基于ABAQUS有限元软件建立了飞机轮胎-土质道面相互作用有限元模型,通过在预设土质道面上改变轮胎胎压、轮胎荷载和运行次数来分析三者对土质道面垂直应力分布和轮辙特征的影响规律,并建立在三者共同影响下的最大轮辙深度数学模型。结果表明,土质道面最大轮辙深度随轮胎胎压、轮胎荷载和运行次数的增大而增大。

全地面起重机用工程机械轮胎不同特征路面力学性能分析

建立了全地面起重机用385/95R25工程机械轮胎带花纹轮胎有限元模型,在验证了模型准确性的基础上分析轮胎在不同特征路面(平面路、横向凸台和纵向凸台)上的力学性能。轮胎充气外缘尺寸和接地数据有限元仿真结果与实测结果一致,表明有限元模型准确、可靠。有限元仿真结果表明:胎肩部位的应力集中于2^(#)带束层端点,应变极值也在此处,横向凸台条件下应力和应变较大;横向凸台条件下,1^(#)带束层帘线张力明显增大,胎体帘线张力在凸台接触区域减小;纵向凸台条件下,1^(#)带束层端点近纵向凸台的接触区域的帘线张力增大,胎体帘线张力变化不大;轮胎的包络刚度约为3000 N·mm^(-1);轮胎在破坏案例中的极限撕裂能为672 J,撕裂能指标对于配方设计有重要的参考意义。

轿车子午线轮胎瞬态冲击特性的仿真研究

以轿车子午线轮胎(简称轮胎)为研究对象,建立轮胎-转鼓有限元模型,并采用隐式-显式仿真分析方法对轮胎瞬态冲击特性进行仿真研究。结果表明:轮胎从较低速度向较高速度转变时,对障碍条的包覆行为存在由完全包覆向非完全包覆转移的现象;随着轮胎速度的增大,轮胎径向力最大幅值变化趋势为增大-减小-增大-减小,周向力最大幅值变化趋势与之相反;径向力衰减特性是轮胎固有属性,不随轮胎速度的变化而变化;在较低速度下负荷越小的轮胎行驶舒适性越好,在中等速度下适量负荷可以保证轮胎行驶舒适性最好,在较高速度下负荷越大的轮胎行驶舒适性越好。

轮胎包络特性及冲击特性的影响因素研究

以215/55R17轮胎为研究对象,研究不同的充气压力与负荷对轮胎包络特性及冲击特性的影响。结果表明:在低速包络试验中,轮胎的径向力峰值随充气压力的增大而增大,随负荷的增大而减小,纵向力峰峰值随充气压力和负荷的增大而增大,但变化幅度不大;在冲击试验中,轮胎的径向力峰值与纵向力峰峰值随充气压力的增大而增大,径向力峰值随负荷的变化受到速度的影响但变化幅度较小,纵向力峰峰值随负荷的增大而增大。

智能轮胎技术的发展

总结智能轮胎涉及的理论和技术发展现状。介绍智能轮胎的概念、特征、功能和分类,并分析国外知名轮胎企业的代表性智能轮胎产品的特点。智能轮胎产品系统基于普通轮胎基本结构特点和性能要求进行开发,融合了当前先进的数字电子技术,对轮胎和车辆工作状态进行有效监控和预测,有助于提高汽车的机动性能、舒适性、安全性及减小燃油消耗,成为汽车安全系统的关键部件。未来的智能轮胎系统以最大限度地提高自动驾驶汽车乘客的舒适性和安全性为主旨,同时最大程度地考虑其他交通参与者的安全和感受。

不同速度和气温对轮胎温度影响的研究

为研究轮胎在不同速度和气温条件下的温度变化,对轮胎转鼓试验室进行温度控制,利用传感器测量不同速度和气温下胎面和胎内温度数据,得出轮胎胎面和内腔随速度和气温变化的温度上升趋势,分析了所测轮胎在不同条件下的温升范围,并详细对比了不同速度和气温条件下胎面、胎内温度稳定值的大小。通过对轮胎温度特性的研究,为轮胎产品的环境适应性分析和验证方法提供了经验,也可作为考虑气温条件的轮胎性能试验和仿真工作的数据参考。

带束层钢丝帘线对半钢子午线轮胎性能的影响

通过成品轮胎室内试验及滚动阻力、静态刚性、接地印痕、六分力和动态冲击特性试验,研究带束层钢丝帘线对半钢子午线轮胎性能的影响。结果表明:3种带束层钢丝帘线成品轮胎的充气外缘尺寸、强度性能、脱圈阻力、高速性能和耐久性能均符合国家标准要求;带束层钢丝帘线主要影响轮胎滚动阻力、接地印痕形状和动态冲击特性,对静态刚性及六分力影响较小。

硫化后充气工艺对子午线轮胎性能的影响

研究硫化后充气时间和压力对轮胎性能的影响。结果表明,延长后充气时间和增大后充气压力会提升初始状态轮胎的外直径和断面宽。后充气时间和压力在不同范围内对轮胎静态接地印痕参数和径向刚度的影响规律不同。从无后充气到有后充气,滚动阻力系数减小;继续延长后充气时间和增大压力,滚动阻力系数不会继续减小。从无后充气到有后充气,侧偏刚度增大,回正刚度减小;随着后充气压力增大,侧偏刚度和回正刚度均增大;后充气时间对侧偏刚度和回正刚度的影响在不同后充气压力下呈现不同的规律。

半钢子午线轮胎胎面胶配方对轮胎刚度特性影响的有限元仿真分析

以245/45R18半钢子午线轮胎为研究对象,建立有限元模型,对轮胎胎面胶配方进行正交试验设计,研究配方对轮胎径向刚度、横向刚度、纵向刚度和扭转刚度的影响。结果表明:胎面胶配方对轮胎扭转刚度的影响最大,其次为纵向刚度、横向刚度,对径向刚度几乎无影响;炭黑N234、白炭黑7000GR和环保芳烃油的用量是影响轮胎刚度的主要因素,轮胎刚度随炭黑N234和白炭黑7000GR用量的增大而增大,随环保芳烃油用量的增大而减小;炭黑N234与白炭黑7000GR呈相互减弱的交互作用,炭黑N234与环保芳烃油、白炭黑7000GR与环保芳烃油为相互增强的交互作用。