Hydroplaning Analysis for Tire Rolling over Water Film with Various Thicknesses Using the LS-DYNA Fluid-Structure Interactive Scheme

Current work studies the transient hydroplaning behavior of 200 kPa inflated pneumatic radial tires with various types of tread patterns. Tires were numerically loaded with a quarter car weight of 4 kN, and then accelerated from rest rolling over a water film with a thickness of 5, 10 and 15 mm on top of a flat pavement. Tire structure is composed of outer rubber tread and inner fiber reinforcing composite layers. The Mooney-Rivlin constitutive law and the classical laminated theory (CLT) were, respectively, used to describe the mechanical behavior of rubber material and composite reinforcing layers. The tire hydroplaning phenomenon was analyzed by the commercial finite element code - LS-DYNA. The Arbitrary Lagrangian & Eulerian (ALE) formulation was adopted to depict the fluid-structure interaction (FSI) behavior. Three different tire tread patterns, i.e. the smooth (blank) tread pattern and the 9 and 18 mm wide longitudinally-grooved tread patterns, were constructed to perform the current transient hydroplaning analysis. Simulated dynamic normal contact force and hydroplaning velocity of tire with a prescribed smooth tread pattern were obtained. The computed results were in good agreement with the numerical and test results given by Okano, et al. (2001) for tire running over 10 mm thick water fluid film. In addition, dynamic contact force of a smooth tread pattern tire rolling on a dry flat pavement was also found to be close to the result reported by Nakajima, et al. (2000). In addition, the effect of fluid water layer thickness on the hydroplaning velocity and normal contact force for tires with smooth tread pattern and longitudinally-grooved tread patterns rolling on a wet roadway analyzed by the LS-DYNA code are reported and discussed.     

马来酸酐改性天然胶乳的制备及应用

以过氧化苯甲酰(BPO)为引发剂,在非隔氧条件下,用马来酸酐(MAH)对天然胶乳进行接枝改性,用傅里叶变换红外光谱法对MAH接枝改性天然胶乳(NR-g-MAH)进行了定性表征,用化学滴定法测定了NR-g-MAH的接枝率和接枝效率。结果表明,当BPO用量为0．8份(质量,下同),MAH用量为4份,MAH与天然胶乳于80℃下反应4h时,可以制备接枝率和接枝效率分别为1．73％和45．33％的NR-g-MAH复合材料。用该复合材料对胎面胶增强用尼龙66短纤维进行预处理．较之未处理尼龙66短纤维填充胎面胶而言,复合材料填充胎面胶的拉伸强度提高了57．6％,撕裂强度提高了21．8％,与乌龙牌DN66预处理尼龙短纤维增强胎面胶力学性能相当。     

Progress of synthesis and application of trans-1,4-polyisoprene

A new technology to synthesize trans-1,4-polyisoprene (TPI) with bulk precipitation polymerization in the presence of a supported Ti catalysts was introduced. The termination of polymerization, stabilization of the polymer, and the adjustment of the molecular weight of TPI and its quality index are discussed. The blending and covulcanization of TPI with natural rubber (NR), styrene butadiene rubber (SBR), and butadiene rubber (BR) were studied. The blending compounds had outstanding dynamic mechanical properties, especially the rolling resistance, heat buildup, and wet skid resistance. Tread and sidewall compounds that contained TPI had a higher modulus, longer fatigue life, better abrasion resistance, lower rolling resistance, and lower buildup, which indicates that TPI is suitable for high-performance tire. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 81–89, 2001     

子午线轮胎专用芳烃油的开发与应用研究

在实验室,利用辽河环烷基原油资源,通过原料筛选、优化调合比例,成功地开发出了满足子午线轮胎生产厂家技术要求的芳烃油,在对辽河芳烃油成功地进行了小配合试验的基础上,又在厂家进行了大配合试验及成品轮胎应用试验,同时与厂家原用子午线轮胎芳烃油进行了等量对比试验。试验结果表明,辽河子午线轮胎芳烃油闪点高、粘度适中、碳型分布理想,用于子午线轮胎胎面胶的混炼加工中,可显著改善其加工性能,同时使硫化胶具有较好的物理机械性能,且生热较低,用作子午线轮胎胎面胶软化剂,可赋予胎面良好的抓着性、耐磨性和较低的滚动阻力,各项性能好于对比芳烃油,是一种比较理想的子午线轮胎芳烃油。     

纳米氧化锌对NR/BR胎面胶性能的影响

试验研究纳米氧化锌对不同并用比NR/BR并用胶性能的影响及其减量替代间接法氧化锌在载重轮胎胎面胶中的应用。结果表明,以纳米氧化锌等量替代间接法氧化锌用于不同并用比NR/BR并用胶中,胶料的t10和t90延长,且随着BR用量的增大,延迟时间进一步延长;硫化胶的300%定伸应力、拉断强度和回弹值增大,二者300%定伸应力和拉断强度的差值随着NR/BR并用比的变化而无明显变化,回弹值的差值随着BR用量的增大而增大;抗撕裂性能和耐疲劳性能下降;以纳米氧化锌减量25%替代间接法氧化锌用于NR/BR(并用比60/40)胎面胶中,可改善胶料的加工安全性,降低生热,提高老化后性能,成品轮胎的耐久性能有所提高。     

白炭黑175GR在载重轮胎胎面胶中的应用

研究白炭黑175GR在载重轮胎胎面胶中的应用.回归分析试验结果表明, 白炭黑175GR与炭黑采用适当的比例并用,可使胎面胶压缩生热明显降低,抗撕裂性能和弹性显著提高,拉伸强度和拉断伸长率有所提高,抗屈挠龟裂性能有所改善.     

速率及气压对轮胎胎面胶摩擦性能的影响

采用高速摩擦机对不同速率和气压下胎面胶的摩擦性能进行研究.结果表明,固定速率,随着气压的增大,摩擦因数减小,摩擦力先减小后增大;固定气压,随着速率的增大,摩擦因数减小.在对摩擦因数随速率和气压变化规律进行分析的基础上,得到摩擦因数随两因素变化的经验关联式,可用于初步计算轮胎胎面胶的摩擦因数及分析轮胎胎面在路面上滑移时的温升,为轮胎温度场的研究提供必要参数.     

环保型促进剂XT-580在载重轮胎中的应用

研究环保型促进剂XT-580等量替代促进剂NOBS在载重轮胎胎面胶和胎侧胶中的应用效果.结果表明,促进剂XT-580等量替代促进剂NOBS对胶料硫化特性和物理性能无不利影响,其中胎侧胶强伸性能和胎面胶耐磨性能稍有提高;试制的7.50-16 12PR轮胎综合物理性能和速度性能稍优于正常生产轮胎.使用促进剂XT-580能降低成本.     

高速转向架非线性稳定性及安全裕度对策

为了满足新一代高速转向架的安全稳定性裕度要求,在构架振动报警原因分析的基础上,提出了抗蛇行减振器软约束技术对策。运行稳定性分析是指包括临界速度和动态行为在内的综合评价。临界速度取决于轮轨匹配特征,其对轮轨接触及转向架的非线性变化也将产生非常敏感的影响。动态行为评价是按照相关标准规范要求进行的构架横向加速度等安全指标评价。尽管在超临界分叉下轮对小幅值蛇行,但是由于抗蛇行减振器具有高频卸荷机制,拖车转向架动态行为也有可能达到或超过安全限制。构架横向加速度频响对比分析表明：转向架蛇行振荡是其振动频响的主要谐振成份,可以采用抗蛇行减振器软约束方式加以控制。     

邻域粗糙集在轮对踏面缺陷图像特征选择的应用

邻域粗糙集理论能够直接处理数值性数据,无需离散化,已经被应用在属性选择和分类器设计中;文中在分析了轮对踏面缺陷图像的成像特征的基础上,首先从缺陷样本中提取了16个特征值,然后基于邻域粗糙集知识约简的思想,提出了一种轮对踏面缺陷图像特征的选择方法,实现了对原始特征的优化选择,利用径向基函数神经网络和选择的特征值对缺陷进行分类;实验结果表明,该方法可将识别的原始特征下降到原始特征数目的20%左右,擦伤识别率提高了68%。