辐板式塑料轮胎接地性能的有限元分析

以ABAQUS有限元分析软件为平台,建立了辐板式非充气塑料轮胎的三维有限元模型,在模型计算中考虑了静负荷、稳态滚动和侧偏滚动工况,得出轮胎胎体等效应力和胎面接触应力的分布规律以及此轮胎径向刚度和横向刚度特性曲线,并对这些结果进行了深入的分析,为轮胎结构的优化奠定了基础,为车辆平顺性和操纵性的预测提供了合理的依据.     

轮胎结构有限元分析应用于轮胎结构优选Ⅰ.胎体反包高度的优选

作为轮胎结构有限元分析应用于轮胎结构优选方面的例子,探讨了载重子午线轮胎胎体反包高度的优选问题。通过对胎体反包端点、带束层点、胎户附近单元的应力分析参数及胎圈附近胎体张应力的综合分析,认为３１３低网格对应的胎体反包高度比３１３网格和３１３高网格对应的两种胎体包高度更合适。     

新型PU胎面/橡胶胎体复合结构绿色轮胎力学性能有限元分析及结构优化

利用三维非线性有限元分析软件对新型PU胎面/橡胶胎体复合结构轮胎的力学性能进行有限元分析,并根据有限元分析结果,对PU弹性体胎面材料和轮胎结构进行优化,试验结果表明,胎冠粘合层位置的受力情况和轮胎的耐久性得到改善.     

新型子午斜交胎结构设计与力学性能研究

如今优越的承载性能、操控性能和安全性能成为了轮胎行业未来发展的主旋律,然而由于高扁平率的轮胎在使用过程中胎肩变形难以控制导致轮胎接地压力分布均匀性较差,从而影响轮胎的磨损性能和安全性能。基于子午胎和斜交胎的胎体结构和性能对比,提出了一种新型的子午斜交胎体结构,利用有限元软件ABAQUS建立子午斜交胎的三维有限元模型,并对其进行接地性能和骨架材料力学性能分析。研究结果表明,子午斜交胎体结构通过提高胎侧刚性和控制胎肩变形,减小了胎肩的应力集中,改善了轮胎接地压力分布均匀性,避免了轮胎断面轮廓畸变,提高了轮胎的承载性能、耐磨性能和操控性能。     

PU胎面/橡胶胎体复合结构绿色轮胎及其制造方法

简介绿色轮胎的发展和PU胎面／橡胶胎体复合结构绿色轮胎的制造方法。PU胎面／橡胶胎体复合结构轮胎综合了橡胶胎体和PU弹性体胎面的优点，耐磨性能和耐疲劳性能优异；成型工艺简单，不需改变原有轮胎橡胶胎体，将PU直接浇注在橡胶胎体上即可；无需胎面挤出、成型、硫化设备。     

受力轮胎花纹块与胎体变形量测试系统的研究

开发了一种测量在径向力、切向力和侧向力作用下轮胎胎面花纹块变形量和胎体变形量等参数的试验系统。该系统可以在不同条件下进行如下参数的测量 :轮胎胎面花纹块变形量、胎体变形量、轮胎的接地印迹、轮胎下沉量及滚动半径、轮胎与路面的摩擦因数、轮胎径向刚度、侧向刚度和切向及扭转刚度等。该系统为汽车的动态仿真提供更接近实际的轮胎模型及参数数据 ;可以验证轮胎有限元计算结果的精度和误差 ;为轮胎的振动与噪声仿真计算与分析提供了理论依据。重要的是可以通过该系统研究轮胎结构参数与轮胎各种性能的关系 ,以缩短新产品的开发周期。     

子午斜交轮胎力学性能有限元分析

提出一种新型子午斜交轮胎结构,即将子午线轮胎胎侧部位的胎体帘线子午结构改为斜交结构,并利用有限元模型对子午斜交轮胎和子午线轮胎的特性进行对比分析.结果表明:与子午线轮胎相比,子午斜交轮胎的径向刚度较高;胎侧应变能密度分布较连续且相对均匀,且最大应变能较低;胎面横向接地压力分布较均匀、尤其是胎肩处的应力集中区域较小,接地印痕形状近似椭圆形;带束层边缘的剪切应变峰值较小.     

轮胎结构有限元分析应用于轮胎结构优选Ⅱ.带束层宽度的优选

作为轮胎结构有限元分析应用于轮胎结构优选方面的例子,探讨了轮胎带束层宽度的优选问题。通过对带束层端点,胎体反包端点,胎肩附近单元的应力分析参数及胎圈附近胎体张应力和带束层张力的综合分析,认为３８６中网格对应的带束层宽度比３８６窄网格和３８６宽网格对应的带束层宽度更合适。     

新型子午斜交轮胎结构设计与力学性能研究

提出一种新型子午斜交轮胎胎体结构,利用有限元软件Abaqus建立三维有限元模型,并对其接地性能和骨架材料力学性能进行分析。研究结果表明,子午斜交轮胎结构通过提高胎侧径向刚性和控制胎肩变形,减小了胎肩的应力集中,改善了轮胎接地压力分布均匀性,避免了轮胎断面轮廓畸变,有利于提高轮胎的承载性能、耐磨性能和操控性能。     

免充气蜂巢式轮胎接地性能的有限元分析

建立免充气蜂巢式轮胎与地面接触的有限元模型,进行接地性能的相关分析.研究结果表明,与充气轮胎相比,胎面采用聚氨酯弹性体、胎体采用聚甲醛塑性材料的免充气蜂巢式轮胎具有更大的径向刚度和横向刚度,表明在降低滚动阻力和增强操控稳定性方面有优势,但是其胎面中心区域的接触应力最大,造成该区域磨损较为严重.     

生物活性多糖结构与功效关系的研究进展

生物活性多糖具有抗肿瘤、抗病毒、降血糖、降血脂等多种生物功能,其功能与结构密切相关。多糖结构与功能关系的研究已经成为人们关注的一个热点。本文综述了生物活性多糖的结构及其构效关系。     

阻尼结构对复合结构阻尼性能的影响

对比自由阻尼结构和约束阻尼结构的阻尼性能,研究基板、阻尼层、约束层对约束结构阻尼性能的影响。结果表明：约束结构阻尼性能相较于自由结构更好;约束阻尼结构中,基板越薄,阻尼层和约束层越厚,复合结构阻尼性能越优异。     

Structure of Spinel

This paper reviews the crystal structure of compounds with the general formula AB₂X₄, which crystallize with the same atomic structure as the mineral spinel, MgAl₂O₄. Three degrees of freedom associated with the detailed atomic arrangements of spinels are considered here: (i) the lattice parameter, a ; (ii) the anion parameter, u ; and (iii) the cation inversion parameter, i. Oxide spinels are used as examples to explore the interrelationships between these parameters.     

Structure of nanodiamonds

The structure of nanodiamonds is considered within the model of icosahedral nanoparticles with a local diamond-like order and a shell structure. The diffraction from nanoparticles with noncrystallographic (in particular, icosahedral) packings of atoms is analyzed. It is demonstrated that the method proposed for calculating the intensity of coherent scattering by clusters of identical polyatomic aggregates is applicable to the entire diversity of carbon structures existing in the nanoworld.     

离聚体的结构及其影响因素

离聚体中的离子对具有一定的配位结构,由于离子对的聚集作用能形成多重离子对或离子簇结构;离子对含量、离子对的特性、聚合物基质的性质、增塑剂、吸收的水份及热作用等都将影响离聚体的结构.本文对这些内容进行了综述.     

Band Structure Calculations of the High-Temperature Electronic Structure of Magnesium Oxide

The effects of high temperature on the electronic structure of a material consist of two major contributions, thermal lattice expansion and the electron-phonon interaction. These can produce dramatic changes in the electronic structure and play a critical role in the high-temperature properties and behavior of ceramics. We have used ab initio pseudofunction band structure methods to calculate the temperature dependence of the electronic structure of MgO from 300 to 1300 K modeling the independent effects of thermal lattice expansion and the electron-phonon interaction. The band structure calculations were performed self-consistently on a (MgO)₄ supercell using experimental values obtained from high-temperature X-ray diffraction to determine the lattice constants up to 1300 K and the root mean square amplitude of phonon displacements. Lattice thermal expansion contributed -0.15 meV/K to the band gap temperature dependence. Individual phonon modes, with displacements in the 〈111〉, 〈110〉, and 〈100〉 directions, were modeled using distorted lattice calculations. The electron-phonon coupling was found to be strongest for the 〈100〉 mode modeled, with strong coupling seen for modes which lead to the smallest decrease in the Mg-O bond length. The overall magnitude of the electron-phonon contribution to the band gap temperature dependence for the phonon modes modeled was −0.95 meV/K. The theoretical results account for a band gap temperature dependence in MgO of −1.1 meV/K, which compares well with the temperature dependence of approximately −1 meV/K determined experimentally using vacuum ultraviolet spectroscopy.     

应用“知识逻辑结构教学法”提高结构化学教学质量

论述了结构化学课程的特点和教学中的主要矛盾,总结了常规教学方法的局限性,找到了提高结构化学教学质量的有效途径:即采用"知识逻辑结构与思维形式注记教学法",制作并使用"知识逻辑结构呈现式"课件,并适当结合"启发式教学法"。     

铅基复合钙钛矿型材料的电子结构和介电性能

采用CASTEP软件对不同B位取代的Pb(BⅠBⅡ)O3材料的电子结构进行计算,从离子价键、电子态密度等方面研究了铅基复合钙钛矿型材料介电性能差别巨大的原因.结果表明:在较大B位离子撑起晶体结构的前提下,较小B位离子的d轨道和O-2p轨道的相互作用是影响弛豫铁电体介电常数的主要因素;计算结果与文献的实验结果一致.说明介电性质与晶体的电子结构直接相关,为进一步从电子结构出发研究此类材料的介电理论模型提供了参考.     

Structure of polystyrene glasses

Wide-angle X-ray scattering from both unoriented and axially deformed glassy polystyrenes (atactic and quenched isotactic) is compared with that calculated for isolated molecules in different conformations. No satisfactory fit is obtained. It is apparent that the scattering beyond $\text{s=1.0}\text{A}\text{?}{}^{\mathrm{?1}}$ is very similar to that from benzene and styrene, having a large contribution from contacts between phenyl groups attached to neighbouring molecules which are not represented in a single chain model. The only significant difference between the scattering of the polymer and the two low molecular weight liquids is that there is a small peak at $\text{s=0.75}\text{A}\text{?}{}^{\mathrm{?1}}$ (0.62 Å^?1 for the isotactic glass) which forms on polymerization and was first reported by Katz in 1927. For drawn samples the peak intensifies on the equator and apparently represents interchain correlations. However, in comparison with those of other non-crystalline polymers this interchain peak is weak, at a surprisingly low scattering angle in relation to the expected spacing of the chains and shows a very significant increase in intensity with increasing temperature. A model is proposed in which the phenyl groups segregate on a molecular scale to form stacks; there are fewer stacks than chain backbones and they have a low electron density core which expands considerably in relation to its small diameter as the sample temperature increases. The model accounts for the position and temperature sensitivity of the interchain ‘polymerization’ peak. It also shows some similarities to the organization of isotactic molecules in the crystalline state. The stacks of phenyl groups contribute to the X-ray pattern as if they were flexible superchains. The cylindrical distribution function derived from the scattering pattern of the oriented polymer indicates that the phenyl groups are in register in all directions over distances of the order of several chain diameters.     

Film Structure and Adhesion

Paint films although attached to a substrate on one side only may be subjected to stresses, comparable to those in structural adhesives. These stresses result from shrinkage during film formation and subsequent ageing, mechanical strains, relative thermal movements of film and substrate and from osmotic pressure due to soluble material under or within the film. The adhesive strength required to prevent detachment varies from very little for weak, highly porous coatings to 10,000 lb/in² for tough coatings of high elastic modulus. Generally, adhesive strength both to the substrate and between coats in a paint system must exceed cohesive strength, under the conditions when failure is likely to develop. Dispersion and other forces, such as hydrogen bridging, between coatings and clean metal substrates should suffice to ensure adhesion but most practical surfaces carry contaminants, which interfere with wetting and intimacy of contact. Solvents and other low molecular weight components may also provide a weak interfacial layer, at least for a period after application. Modification of polymer structure to improve contaminant displacement and to increase polymer/substrate interaction forces, for example by the introduction of polar substituent or end groups will be discussed and potentialities of adhesion-promoting surface treatments reviewed.