轮胎非稳态侧偏特性的试验分析与试验设计

分析了轮胎非稳态侧偏特性的试验原理,利用低速平板式轮胎试验台,设计并实现了纯转向和纯侧向运动试验,为轮胎力学和汽车动力学的建模、仿真及分析提供了试验数据。     

Imports and Exports of Rubber Raw Materials and Rubber Products in China in Jan.-Apr. 2014

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Overseas News

Goodyear’s First-quarter Revenue Achieving a Yearon-year Increase of 24%On April 29,Goodyear Tire&Rubber Company published its financial report of the first quarter in 2014,in which its quarterly revenue achieved a year-on-year growth.Mr.Richard J.Kramer,the president&CEO of Goodyear,said that the financial objective of 2014~2016was confirmed unchanged.And the Company highlighted its     

Mechanical and Morphological Properties of Polypropylene and Regenerated Tire-Rubber Blends

Mechanical properties and morphology of blends prepared from polypropylene (PP) and 5–20 wt% of regenerated tire-rubber (RgR) were studied. The samples were prepared in a twin-screw extruder. The addition of maleic anhydride-functionalized polypropylene (PP-g-MAH) was also investigated. Tensile and flexural moduli, tensile strength at break, elongation at break and Izod impact resistance at 23°C were increased by the addition of 15 wt% of regenerated rubber and 5 wt% of PP-g-MAH. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses showed some interaction between PP and RgR and considerable modification of the compatibilized mixture morphology. The fracture surface of the blend with PP-g-MAH showed a better interaction between the PP matrix and the regenerated rubber domains, for all blends. Well-dispersed particles of the rubber in the polypropylene matrix were observed. DSC showed that PP crystallizes on cooling at lower temperatures as the RgR content increases. The decrease in crystallization temperature is more evident for blends with 5 wt% PP-g-MAH.     

基于轮胎非线性模型的汽车操纵系统的动力学分析

基于一种轮胎非线性侧偏特性模型,利用近似解析方法研究了汽车的操纵动力学问题,给出了表征汽车稳态响应的横摆角速度增益、转向半径之比、前后轮侧偏角之差的近似解析解.结果表明,当前轮输入角较大时,稳态横摆角速度增益会迅速增加;而当车辆高速行驶时,即使前轮输入角很小,转向半径之比也会很大.与线性轮胎侧偏特性模型相比,考虑轮胎侧偏特性的非线性时,转向不足的区域明显减小.     

Evaluation on hydrothermal gasification of waste tires based on chemical equilibrium analysis

Massive amounts of waste tires are produced globally, which brings great challenges to the disposal and recycling of used tires. Hydrothermal gasification is a promising option for recycling waste tires. The hydrothermal gasification of waste tires was evaluated based on the chemical equilibrium analysis along with the response surface methodology (RSM) in terms of subcritical temperature range (250–300 °C), transition temperature range (350–400 °C), supercritical temperature range (550–600 °C), supercritical pressure (22.5–30.5 MPa) and feedstock concentration (5–20 wt%). CH₄ yield at 350 °C reached a maximum, 41.575 mmol/g. H₂ yield increased from 0.0283 to 53.602 mmol/g with increasing the temperature from 250 °C to 600 °C. CH₄ yield at the supercritical temperature increased with lifting the feedstock concentration, while H₂ yield decreased. The optimal parameters regarding maximum H₂ and CH₄ yields in the subcritical temperature range were 300 °C, 22.5 MPa and 12.5 wt%, respectively, while they in the supercritical temperature range were 550 °C, 30.5 MPa and 5.4 wt%, respectively. RSM was more suitable for predicting H₂ yield in the hydrothermal gasification of waste tires at subcritical and supercritical temperature ranges, but it was available for predicting CH₄ yield in three temperature ranges. This study can provide basic data for the hydrothermal treatment of waste tires.     

Catalytic pyrolysis of olive cake and domestic waste for biofuel production

The development of waste-to-energy technologies provides an integrated approach to waste management, climate protection, and sustainable devolvement. In this study, biofuels were produced from “olive cake” combined with used paper and scrap tire. A lab-scale facility was designed to carry out catalytic pyrolysis of a solid feedstock comprising 5 wt% used paper, 5 wt% scrap tire, and 90 wt% olive cake. Jordanian volcanic tuff was used as a catalyst during pyrolysis. The catalytic pyrolysis produced various proportions of gaseous, liquid, and solid biofuels. The use of catalyst influenced the composition, quality, and yield of products via cracking and reforming reactions.     

橡胶改性沥青在路面工程中的应用

介绍了橡胶改性沥青在路面中的应用历史、现状和应用效果,并对橡胶改性沥青与沥青混合料的性能以及橡胶改性沥青应用的经济和环保效益进行了分析.与其它改性沥青相比,橡胶改性沥青具有明显的优势,应大力推广.     

车辆稳定控制中的合力计算与分配

控制地面作用于车辆的纵侧向合力与横摆转矩并将其分配到4个车轮,是车辆平面运动稳定控制的方法之一.路面的附着极限决定了合力与横摆转矩的可行域,是该方法的约束条件.本文分析了轮胎的受力特点,在摩擦椭圆理论的基础上,给出了简化的纵侧向力耦合关系.利用非线性规划方法和大量的数值计算,解决纵向合力与横摆转矩可行域的实时估计问题.构造了一种控制结构,外环控制器计算可行的纵向合力与横摆转矩;内环控制器首先将纵向合力优化分配到4个车轮,然后通过调节前轮转角使横摆转矩跟踪期望值.仿真结果表明,采用本文提出的方法对车辆进行控制,能够实现横摆角速度的快速准确跟踪,并使车辆具有良好的操纵稳定性.     

Laboratory large-scale pullout investigation of a new reinforcement of composite geosynthetic strip

In this paper, more than 70 large-scale pullout tests were performed to evaluate the performance of an innovative composite geosynthetic strip(CGS) reinforcement in sandy backfill. The CGS reinforcement is composed of a geosynthetic strip(GS) and parts of a scrap truck tire as transverse members. The experimental pullout results for the CGS reinforcement were compared with the suggested theoretical equations and ordinary reinforcements, including the GS, the steel strip(SS), and the steel strip with rib(SSR). The pullout test results show that adding three transverse members to the GS reinforcement(CGS_3) with S/H=6.6(where S and H are the space and height of the transverse members, respectively)increases pullout resistance by more than 120%, 170%, and 50% compared to the GS, the SS, and the SSR,respectively. This result shows that the CGS_3(CGS with three transverse members) reinforcement needs at least 55.5%, 63%, and 33.3% smaller length compared to the GS, the SS, and the SSR, respectively. In general, implementation of mechanically stabilized earth wall(MSEW) with the proposed strip may help geotechnical engineers prevent costly designs and solve the problem of MSEW implementation in cases where there are limitations of space.