185/70R14轮胎的稳态滚动仿真分析及试验对比研究

采用大型通用有限元仿真分析软件,建立185/70R14轮胎的静态和稳态滚动仿真分析模型,考察不同状态下子午线轮胎内部受力、印痕形状以及外缘尺寸等.结果表明,不同速度下仿真计算半径与实测半径相对误差小于2%;随着速度的提高,印痕形状接近蝴蝶形,胎肩压力增大;肩部带束层骨架材料和带束层端部橡胶材料应变能密度和应力、应变均随速度的提高而增大.     

静态及滚动状态下轮胎接地印痕的有限元分析

使用ABAQUS有限元分析软件,考虑了轮胎的材料非线性、接触非线性以及大变形等复杂的力学特性,建立了光面和带有花纹块的185/70R14半钢子午线轮胎的两个三维有限元分析模型,通过改变气压、速度和摩擦系数等参数,得到了光面轮胎在静态接地、稳态滚动、加速刹车和侧偏工况下的接地印痕,研究了不同气压、载荷、速度和摩擦系数下接地印痕的变化;得到了带有花纹块轮胎的静态接地印痕,并考察了不同载荷下该印痕的变化。     

考虑腔内压力变化的航空轮胎静载仿真研究

针对分布压力模拟航空轮胎充气压力无法反映腔内压力变化的问题,采用流体腔模拟航空轮胎充气结构,进行航空轮胎静载仿真研究。采用Yeoh橡胶材料本构模型和Rebar帘线层加强筋单元建立某型航空轮胎二维几何模型,通过修改INP文件,建立航空轮胎流体腔三维仿真模型。对静载工况下分布压力模型和流体腔模型航空轮胎进行分析,结果表明:在自由充气阶段,不同充气压力下2种模型轮胎的断面宽及外直径相等;轮胎下沉量小于10 mm时,2种模型轮胎径向刚度基本相同,当轮胎下沉量达到30 mm时,流体腔模型轮胎径向刚度比分布压力模型轮胎大3%～4%;流体腔模型轮胎腔体体积与腔内压力呈近似反比例关系。     

基于有限元仿真的轮胎噪声模拟分析

以225/50R16半钢子午线轮胎为研究对象,采用Abaqus软件,按照真实轮胎静负荷试验工况对其进行模拟分析,得到仿真接地印痕,并进行轮胎噪声模拟。结果表明:仿真接地印痕的长轴、短轴和平均接地压力与实测结果的相对误差在1.5%以内;将仿真印痕参数导入噪声分析软件,80 km·h~(-1)速度下的轮胎噪声模拟计算结果与实测噪声结果的差值在1 dB以内。     

轮胎临界速度的预测

高速驻波对轮胎不利。美国宾夕法尼亚州大学与美联邦能源署（FEA）一起正对其危险等级进行预测。在车辆中，轮胎是最复杂的部件。轮胎性能，特别是高速时的性能，是安全与否的临界点。每一种轮胎都有一个最大速度值，通常是由轮胎制造厂给出的。轮胎在正常操纵条件下，存在一个临界速度。一旦轮胎达到这一临界速度，便产生波状变形，这一变形发生在轮胎周界，很容易观察到，称为驻波现象。近似预测这一临界速度的理论于１９５４年由Turner成功建立。该理论可以下式表述：C＝Tρ√式中：C是波的传播速度，即产生驻波的临界速度；T是轮胎…     

基于疲劳裂纹扩展理论的轮胎橡胶疲劳寿命预测

建立了轮胎断面模型和三维有限元模型,模拟了轮胎稳定滚动时断面上各部件橡胶材料的负荷情况。基于橡胶疲劳裂纹扩展理论和临界平面法,计算了轮胎模型滚动情况下橡胶材料的疲劳寿命,并研究了轮胎橡胶材料疲劳寿命随负荷的变化情况,同时比较了不同负荷下轮胎各部件橡胶材料疲劳危险点的分布。     

PCR轮胎滚阻仿真计算及验证

本文介绍了一种基于ABAQUS软件计算滚动阻力的方法,提取轮胎静载工况下的应变、应力等印痕信息再结合胶料的损耗因子计算轮胎温度场分布及滚动阻力。在185/65R14规格轮胎对仿真结果进行了验证,结果表明FEA与试验测试得到的滚阻数值有差距,但是变化趋势及幅度基本吻合。该仿真方法可以有效预测调整结构、胶料后对PCR轮胎滚阻的影响。     

基于带束层模型的全钢子午线轮胎接地印痕仿真精度提升的研究

以4层带束层结构和3层带束层＋0°带束层结构的全钢子午线轮胎为对象,研究带束层模型对轮胎接地印痕仿真精度的影响。结果表明：对于4层带束层结构轮胎,成型和硫化后带束层角度发生变化,根据带束层角度变化规律对仿真模型进行修正,可提升轮胎接地印痕的仿真精度;对于3层带束层＋0°带束层结构轮胎,0°带束层高伸长钢丝帘线采用超弹性模型表征可提升轮胎接地印痕的仿真精度。     

基于Abaqus的全钢轮胎接地印痕仿真分析

以215/75R22.5和315/70R22.5全钢轮胎为研究对象,通过有限元仿真分析方法模拟轮胎的接地印痕,并量化表征接地印痕形状,将实际测试结果与仿真结果进行了对比。结果表明:行驶面弧度高和胎冠弧半径都对轮胎接地印痕形状产生影响,不同胎冠弧设计方案的轮胎接地印痕形状差异很大;轮胎接地印痕仿真分析精度满足设计需求,可以用于轮胎设计初期的结构优化,有利于提高轮胎性能和节约开发成本。     

基于有限元分析的轮胎接地印痕研究

借助有限元分析对轮胎的接地印痕进行模拟分析,通过建立三维有限元分析模型,改变负荷、气压、速度和摩擦系数等参数,得到不同状态接地印痕结果。通过选取225/45R17作为实例分析,阐述通过有限元分析对三种设计方案的轮胎接地印痕进行模拟仿真。根据不同的产品开发要求,选定较好的设计方案,能大大地提高轮胎质量,缩短新产品研发周期,提高产品竞争力。     

乙苯,苯乙烯的生产及合成乙苯,苯乙烯催化剂的研究进展

苯乙烯是重要的石油化工原料。本文介绍了国内外苯乙烯生产的发展概况，合成乙苯，苯乙烯所用的催化剂种类，并就苯乙烯生产及催化剂的发展趋势提出了自己的观点。     

Synthesis and characterization of homopolymers and copolymers of various acrylates and acrylonitrile

Various homopolymers and copolymers of methyl acrylate, ethyl acrylate, butyl acrylate, and acrylonitrile in different feed ratios were synthesized. These were characterized by IR, ¹³C-NMR, DSC, DTA, and TGA. Spectroscopic characterization helped in differentiating copolymers of different mol ratios. Thermal analysis revealed different degradation patterns for homopolymers and copolymers. The temperature and energy changes associated with various phase transitions were dependent on the chemical composition of homo- and copolymers, as expected. © 1993 John Wiley & Sons, Inc.     

生物质气化及生物质与煤共气化技术的研发与应用

总结了生物质原料的特点及生物质单独气化的缺点;介绍了国内外生物质气化技术及生物质与煤共气化技术的研发与应用现状;分析了在此领域国内外的发展趋势与前景;概括了开展生物质与煤共气化技术研发的意义。     

责任和责任心的涵义与结构

责任是人应主动承担的角色义务和对其因过失所造成后果应承担的责罚.有两层涵义:一是义务;二是后果.责任心是个体自觉做好分内事务和履行道德义务的心理倾向,是个性心理品质成分中自我特征维度上的重要内容.责任心具有两个方面的涵义:一是角色分内职责;二是角色道德义务.责任心是一种通过责任认知、责任个性和责任适应的动态形式表现出来的静态品质,责任心是责任心过程结构与责任心关系结构相互制约、相互影响的统一体.     

二甲基二烯丙基氯化铵和丙烯酰胺的合成及应用

用复合引发体系(过硫酸盐-偶氮类引发剂)和脂肪胺类氧化还原体系引发,在实验室获得了单体转化率≥98%,特性粘数高于13.6 dL/g的阳离子共聚物PDA,探讨了控制聚合物分子量的影响因素.     

Comparison of the Adhesion and Cohesion of Triblock and Random Copolymers of Styrene and Butadiene

A substantially greater detachment energy is required to strip a polyethylene tereph-thalate (Mylar) film from a styrene-butadiene-styrene (SBS) triblock copolymer compared to that for peeling from a random styrene-butadiene (SBR) copolymer. This is true even though the intrinsic interaction between the Mylar and each elastomer is expected to be similar because of their virtually identical chemical composition. It is proposed that this difference in peel strength (between the SBS and SBR) is a consequence of the much higher dissipative capacity of the former elastomer. Another manifestation of this is the higher cohesive tear strength of the SBS compared to the SBR. Extents of energy dissipation within each elastomer during detachment of the Mylar adherend are consistent with the hypothesis that the average maximum stress experience before detachment is some similar fraction of each elastomer's tensile strength.     

钾盐资源及钾肥供需情况分析及预测

阐述了国内外钾盐资源及钾肥生产现状,对国内外钾盐的供需形势进行了分析及预测,从资源、原材料、国际市场三方面提出了解决我国钾盐短缺的措施。     

Electronic structures and reactivities of monometallic and bimetallic clusters of Au and Cu

The variation of the Au 4f binding energy of Au clusters with the cluster size has been established by measuring the binding energies of clusters whose size distributions were independently determined by HREM and STM. The binding energy increases significantly when the cluster size is less than 2 nm. Au-Cu bimetallic clusters of the composition Cu₃Au have been deposited for the first time on carbon substrates. The shifts in the core level binding energies of the bimetallic clusters show the effect of alloying in the case of large clusters, but show effects of both alloying and cluster size in the case of the small clusters. The interaction of CO with Cu₃Au clusters is stronger than with a bulk Cu metal. The interaction of CO with small Cu clusters also seems to be stronger than with bulk Cu or with large Cu clusters.     

Wetting properties of homopolymers and copolymers of pentafluorostyrene and methylacrylate and homopolymer blends

Polypentafluorostyrene (PPFS), polymethylacrylate (PMA), and poly(pentafluorostyrene-co-methylacrylate), poly(PFS-co-MA) were prepared and the wetting characteristics of polymer blends of PPFS and PMA were compared with that of poly(PFS-co-MA) via contact angle measurements. The critical surface tension of polypentafluorostyrene was found to be 22.6 dyne/cm, which is comparable to the value reported for polytrifluoroethylene (22 dyne/cm). The critical surface tension of poly(PFS-co-MA) is not linearly related to its composition. The polymer blends of PPFS and PMA exhibit significant surface enrichment of the fluoropolymer. The harmonic-mean method¹ was employed to determine surface tensions of these polymers and many known polymers. It is found that the method produces useful surface tension data provided the contact angle values are derived from testing liquids of dissimilar polarity.