橡胶空气弹簧隔振设计及性能分析

橡胶空气弹簧是气囊减振器,随着各种精密仪器的广泛应用,这些精密仪器的使用对外界环境的要求也越来越高.在隔振方面,用橡胶空气弹簧进行隔振,减少了外界环境对各种精密仪器的影响.本文具体剖析了橡胶空气弹簧的隔振设计和隔振性能,表明橡胶空气弹簧在一些高精度仪器、工业设备以及车辆上的一些隔振设计是合理可行的.     

汽车悬架空气弹簧静态力学性能有限元建模与计算

以一款膜式橡胶空气弹簧作为研究对象,进行了三维建模和静态力学特性有限元分析,并与实验测试结果对比,验证了采用有限元软件对空气弹簧的建模与力学性能计算结果的准确性与可行性。文中的有限元建模和计算方法对空气弹簧力学性能计算分析与优化设计具有一定的指导意义。     

动态力学分析在氟橡胶热空气老化分析中的应用

以硫化结构不同的普通氟橡胶及全氟醚橡胶为研究对象,通过动态力学分析研究其热空气老化性能,并结合常规拉伸性能测试对动态力学分析结果进行验证.结果表明,当出现明显的老化现象时,普通氟橡胶及全氟醚橡胶的力学损耗均有明显增大的趋势,同时拉伸强度会出现明显的减小.氟橡胶的硫化结构对其热空气老化性能有重要影响,在250℃下老化24...     

A new method to predict optimum cure time of rubber compound using dynamic mechanical analysis

The degree of vulcanization of a rubber compound has a big influence on the properties of the final product. Therefore, precisely defining the curing process including optimum cure time is important to ensure the production of final products having high performance. Typically, vulcanization is represented using vulcanization curves. The main types of equipment used for producing vulcanization curves are the oscillating disc rheometer (ODR) and the moving die rheometer (MDR). These can be used to plot graphs of torque versus time at a constant temperature to show how cure is proceeding. Based on the results obtained, optimum cure time (t₉₀) is calculated as the time required for the torque to reach 90% of the maximum achievable torque. In this study, the use of Dynamic Mechanical Analysis (DMA) for assessment of t₉₀ was assessed. DMA was carried out using shear mode isothermal tests to measure the changes in material properties caused by vulcanization. The results revealed that the shear storage modulus (G′), shear loss modulus (G′′) , and tan δ all reflect the vulcanization process, however, tan δ gave the best representation of level of vulcanization. Indeed, the curve of tan δ was able to be used to derive the t₉₀ for rubber compounds and showed good agreement with the results from an MDR. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40008.     

Crystallization behaviors and mechanical performance of polypropylene/tetrapod‐shaped zinc oxide whisker composites

Polypropylene (PP)/tetrapod‐shaped zinc oxide whisker (T‐ZnOw) composites are prepared via a melt‐mixing method in combination with a Haake rheometer. Differential scanning calorimetery (DSC) is used to investigate the nonisothermal and isothermal crystallization behaviors of the composites. Crystalline morphology is observed using hot‐stage optical microscopy, and the mechanical performance of the composites is investigated. Results indicate that T‐ZnOw has no heterogeneous nucleation effect on PP; in fact, it retards the growth of the crystal. Filled T‐ZnOw in PP matrix decreases the peak crystallization and melting temperatures of PP. T‐ZnOw shows either a reinforcing or toughening effect on the PP matrix at very lower weight ratios. These effects, however, decline with increasing T‐ZnOw contents because the size of the spherulitic crystals becomes bigger. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermal and mechanical behavior of natural rubber latex‐silica aerogel film

A major problem in most natural rubber latex (NRL) commonly encountered like other polymer is susceptibility to mechanical properties and thermal degradation; particularly in thin film due to the presence of double bonds in the main chain. Therefore, it is desirable to seek for ways of improving these properties. Silica aerogel is a material with extraordinary properties was believed to have potential enhance properties in NRL films because of its high specific surface area. Therefore, based on the unique character of silica aerogel, NRL‐silica aerogel film was developed by latex compounding and dry coagulant dipping to form thin film where silica aerogel acts as filler. Silica aerogel, synthesized from rice husk was dispersed in a ball‐mill using distilled water for NRL compounding. Results indicate that increasing silica aerogel loading enhances the mechanical properties of the NRL‐silica aerogel film. Effects of postvulcanization processes were also investigated, whereby the best reinforcing effect was obtained at 4 phr silica aerogel loading with leaching postvulcanization condition. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Styrene–butadiene rubber/natural rubber blends: Morphology,transport behavior,and dynamic mechanical and mechanical properties

Blends of styrene–butadiene rubber (SBR) and natural rubber (NR) were prepared and their morphology, transport behavior, and dynamic mechanical and mechanical properties were studied. The transport behavior of SBR/NR blends was examined in an atmosphere of n‐alkanes in the temperature range of 25–60°C. Transport parameters such as diffusivity, sorptivity, and permeability were estimated. Network characterization was done using phantom and affine models. The effect of the blend ratio on the dynamic mechanical properties of SBR/NR blends was investigated at different temperatures. The storage modulus of the blend decreased with increase of the temperature. Attempts were made to correlate the properties with the morphology of the blend. To understand the stability of the membranes, mechanical testing was carried out for unswollen, swollen, and deswollen samples. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1280–1303, 2000     

Effect of thermal exposure on the properties of phenolic composites: Dynamic mechanical analysis

Changes in the dynamic response of glass‐reinforced phenolic composites following thermal exposure at 180^oC for periods of time up to 28 days were monitored using dynamic mechanical analysis. Four phenolic resins were investigated: a resol/novolac blend, a phenolic–furan novolac/resol graft copolymer, a novolac, and a resol. Reactive blending and copolymerization of phenolic resins are currently being investigated to determine if these techniques will produce phenolic resins (and composites) that have improved impact properties and retain the excellent high‐temperature properties of resol and novolac phenolic resins. The results indicate that thermal aging at 180^oC for 1 day led to a more complete cure of all four phenolic resins as indicated by an increase in the temperature of the maximum of plots of both loss modulus (E″) and tan δ versus temperature. The storage modulus (E′) of the composites at 40^oC varied little following thermal aging at 180^oC for 1 day but decreased with increasing exposure time for samples aged 2, 7, and 28 days. Thermal aging led to an increase in E′ at higher temperatures and the magnitude of E′ at a given temperature decreased with increasing exposure time. The magnitude of E″ and tan δ decreased with aging time for all resins, although E″ and tan δ were larger for the blend and copolymer composites than for the novolac and resol composites. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 385–395, 2001     

Thermal analysis and mechanical characterization of maleimide‐functionalized benzoxazine/epoxy copolymers

Maleimide‐functionalized benzoxazine is copolymerized with epoxy to improve toughness and processibility without compromising the thermal properties. The incorporation of maleimide functionality into the benzoxazine monomer results in a high performance polymer. All three possible polymerization reactions are confirmed using Fourier transform infrared (FT‐IR) spectroscopy. While maleimide‐functionalized benzoxazine has a glass transition temperature, T_g, of 252°C, a further 25°C increase of T_g is observed when copolymerized with epoxy. The flexural properties are also measured, and the copolymers exhibit a flexural modulus of 4.2–5.0 GPa. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1670–1677, 2006     

单效蒸发机械压汽海水淡化系统热力性能分析

机械压汽蒸馏海水淡化是唯一消耗机械能的热蒸馏海水淡化方式。文中以单效蒸发机械压汽(SEE-MVC)系统为研究对象,建立了数学模型,分析了重要参数对热力性能的影响,结果表明:压缩机增压比越低、定熵效率越高、蒸发温度越低,则产水比功耗越低、系统回收率越高;综合考虑各种因素,系统蒸发温度在55—70℃、增压比在1.2—1.3为宜。文中还给出了典型条件下对应最小比功耗的系统参数,并讨论了参数特点,可供设计时参考。     

Mechanical properties,flame retardancy,hot‐air ageing,and hot‐oil ageing resistance of ethylene‐vinyl acetate rubber/hydrogenated nitrile‐butadiene rubber/magnesium hydroxide composites

The mechanical properties, flame retardancy, hot‐air ageing, and hot‐oil ageing resistance of ethylene‐vinyl acetate rubber (EVM)/hydrogenated nitrile‐butadiene rubber (HNBR)/magnesium hydroxide (MH) composites were studied. With increasing HNBR fraction, elongation at break and tear strength of the EVM/HNBR/MH composites increased, whereas the limited oxygen index and Shore A hardness decreased slightly. Hot‐air ageing resistance and hot‐oil ageing resistance of the composites became better with increasing HNBR fraction. Thermal gravimetric analysis results demonstrated that the presence of MH and low HNBR fraction could improve the thermal stability of the composites. Differential scanning calorimeter revealed that the glass transition temperature (T_g) of the composites shifted toward low temperatures with increasing HNBR fraction, which was also confirmed by dynamic mechanical thermal analysis. Atomic force microscope images showed MH has a small particle size and good dispersion in the composites with high HNBR fraction. The flame retardancy, extremely good hot‐oil ageing, and hot‐air ageing resistance combined with good mechanical properties performance in a wide temperature range (?30°C to 150°C) make the EVM/HNBR/MH composites ideal for cables application. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of matrix viscosity on the dynamic mechanical performance of magnetorheological elastomers

Anisotropic magnetorheological elastomers (MREs) with different natural rubber matrix viscosities and industrial waste nickel zinc ferrite were prepared in order to assess the dynamic and mechanical performance of the materials. The curing characteristics of the anisotropic MREs were determined using a moving disk rheometer (MDR 2000). The loss tangent (tan δ) was measured through a parallel-plate rheometer over a frequency range of 1─100 Hz (Hz) and a strain amplitude range of 0.1─6%. It was found that tan δ increased with increasing matrix viscosity over the range of frequency and strain amplitude explored. Furthermore, as the matrix viscosity increased, the height of the tan δ peak also increased and the glass transition temperature (T_g) valued shifted to a higher temperature. It was also found that tensile strength and elongation at break increased with increasing matrix viscosity. The SEM micrographs revealed that the columnar structures became longer and thicker with a decrease in matrix viscosity. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48492.     

Influence of the microstructure of gums on the mechanical properties of silicone high consistency rubbers

This paper is devoted to the characterization and processing of high molar mass vinyl‐bearing polysiloxanes in high consistency silicone rubber (HCR) formulations. The molar masses of five different polydimethylsiloxane gums, bearing vinyl groups at the ends and along their chains, were evaluated by size exclusion chromatography and rheometry. ²⁹Si and ¹H NMR spectroscopy allowed the precise determination of the vinyl content and of the distribution in the different polymers. Typical HCRs formulated from these gums were heat‐cured to process silicone rubber materials that were then tested mechanically. The macromolecular properties were correlated to the final material network structure. The amount of reactive vinyl moieties, rather than their distribution along or at the end of chains, is a key parameter to tailor the material mechanical properties. © 2016 Society of Chemical Industry     

加强筋模型在轮胎有限元分析中的应用

利用MSC．Marc软件建立子午线轮胎的三维非线性有限元模型。采用软件中的加强筋模型模拟轮胎中复杂的多层帘线一橡胶复合材料，直接在前处理中定义轮胎中随位置变化的帘线铺设方向，可以真实地模拟帘线一橡胶复合材料的几何和材料非线性，并且能够合理简化模型，提高计算效率和计算精度。模型中还考虑了橡胶材料的非线性和不可压缩性、轮胎大变形导致的几何非线性以及轮胎与轮辋和轮胎与路面的接触非线性边界条件。通过三维非线性有限元分析得到了在充气压力和静负荷作用下子午线轮胎的变形、内部应力分布及接地区压力分布。     

A dynamic mechanical analysis method for predicting the curing behavior of phenol-formaldehyde resin adhesive

In this work, filter paper was proven to be suitable as the substrate for the preparation of dynamic mechanical analysis (DMA) testing specimens to predict the curing behavior of phenol-formaldehyde (PF) resin adhesives for its stability during the curing temperature span. With this method, the curing behavior of PF resin was monitored by DMA in tensile-torsion mode. With the strain curves, the onset of curing temperature of PF resin could be determined clearly. The curing degree of PF resin could be calculated by the integral area in strain curves. The method to combine storage modulus (G′), tan δ, and strain curves together could explain the curing behavior of PF resin more comprehensively than the commonly used method using only G′ and tan δ curves. The DMA test results of PF resin with different viscosity and with accelerator implied the reliability of this novelty method.     

进气方式和气速对卧轮式分级机性能的影响

传统卧轮式分级机内流场分布比较混乱,分级精度普遍不高。本文基于对分级机内气流运动规律的分析,将传统切向进风方式调整为径向进风,分别设计了百叶窗型和多孔型风筛,试验对比了传统切流风筛和上述两种径向进风方式对分级效果的影响。结果表明,径向进风方式对分级流场形成和细颗粒淘洗更有利,不仅可以提高分级机的粗粉产率,同时还可降低粗组分中的细粉夹带量,提高粗、细颗粒分离的程度,改善颗粒分级效果;百叶窗型风筛分级机的分级效果最优,气流经百叶窗风筛可对粗组分进行多层、充分扬析,减少细颗粒误入粗产品的概率,牛顿分级效率较传统切流风筛分级机平均提高约6%;此外,入口气速也对分级精度有较大的影响,但对分级粒径的影响不明显,存在临界入口气速使得综合分级效果最好。为提升涡轮分级机的颗粒分级性能提供了新思路。     

气囊压缩性能有限元分析及实验研究

测量了气囊在压缩变形过程中承载力、内压和压缩高度变化之间的关系,建立了气囊的三维有限元模型,模拟了气囊受均布内压和压缩工况。通过实验及有限元取得的结果来了解气囊的力学性能,对于产品设计、气囊力学分析具有重要的实际指导意义。     

机械蒸汽再压缩蒸发系统的性能分析

机械蒸汽再压缩（MVR）蒸发系统是一种新型高效节能蒸发技术。它有多个单元设备组成,每个操作节点的控制都对系统运行的稳定性和节能效率至关重要,其中包括进料温度、蒸发压强、蒸汽压缩比、冷凝液温度等。若操作条件不当,不仅会大大降低蒸发效率而且会对设备和管路造成损害。本文建立了一套充分利用能源的MVR蒸发工艺流程,并通过理论分析对每个操作节点进行了质量和能量衡算,同时利用Aspen Plus模拟软件建立了系统的流程模拟图。通过对操作单元的变量控制,研究了循环蒸汽量、补充水的量与进料温度、冷凝液温度、蒸汽压缩比以及蒸发压强等之间的变化关系。由数据分析可得：原料在饱和液体时进料最佳,冷凝液的温度应保持与蒸发温度的有效温差在5～8 ℃时较好,压缩机的蒸汽压缩比控制在1.8～2.2较为合理。同时可利用冷凝液和浓缩液的余热对原料预热,补充水也可从冷凝液中直接取用。     

多孔质机械密封耦合润滑模型与密封性能分析

考虑多孔质材料内密封介质渗流与密封端面润滑液膜间的传质耦合关系,建立了一种多孔质机械密封的流体润滑模型,采用有限单元法求解液膜润滑方程和多孔质内部渗流控制方程,研究了膜厚、渗透率、多孔质环几何参数对密封性能的影响规律,揭示了多孔质机械密封的工作机理。结果表明：多孔质机械密封依靠流体静压效应在密封端面成膜,相较于普通平行端面密封,其液膜承载力和轴向刚度更大;随多孔质渗透率的增大,多孔质机械密封泄漏率和开启力逐渐增大,而液膜刚度逐渐减小;液膜厚度的增大会导致泄漏率的增大和开启力的减小,而液膜刚度先增大后减小,且不同渗透率下的最大刚度分别对应不同的膜厚值。研究结果可为多孔质机械密封的工程设计提供新的思路和理论指导。     

多孔质机械密封耦合润滑模型与密封性能分析

考虑多孔质材料内密封介质渗流与密封端面润滑液膜间的传质耦合关系,建立了一种多孔质机械密封的流体润滑模型,采用有限单元法求解液膜润滑方程和多孔质内部渗流控制方程,研究了膜厚、渗透率、多孔质环几何参数对密封性能的影响规律,揭示了多孔质机械密封的工作机理。结果表明：多孔质机械密封依靠流体静压效应在密封端面成膜,相较于普通平行端面密封,其液膜承载力和轴向刚度更大;随多孔质渗透率的增大,多孔质机械密封泄漏率和开启力逐渐增大,而液膜刚度逐渐减小;液膜厚度的增大会导致泄漏率的增大和开启力的减小,而液膜刚度先增大后减小,且不同渗透率下的最大刚度分别对应不同的膜厚值。研究结果可为多孔质机械密封的工程设计提供新的思路和理论指导。