炭黑/白炭黑补强硫化胶的疲劳破坏特性

应用断裂力学的方法解析和预测了天然橡胶采用高耐磨炭黑与白炭黑并用补强体系在疲劳过程中形变能密度的变化，疲劳破坏寿命、断裂特征和能量释放率。结果表明：在天然橡胶中采用高耐磨炭黑与白炭黑并用补强体系，随白炭黑用量的增加，胶料疲劳破坏寿命延长，胶料内部潜在缺陷减小，裂纹扩展速度减慢，形变能密度下降缓慢，胶料的能量释放率增加。     

炭黑补强NR硫化胶疲劳破坏特性的研究

用断裂力学方法研究炭黑N110，N220和N330补强NR硫化胶的疲劳破坏特性。结果表明，随着疲劳时问的延长，3种炭黑补强硫化胶的拉断形变能密度均减小，且炭黑粒径越小，硫化胶的拉断形变能密度降幅越大；炭黑粒径越小的硫化胶内部潜在缺陷越小，但抗裂纹扩展性能越差，疲劳寿命越短；3种炭黑补强硫化胶的疲劳寿命方程均能较准确地预测其疲劳寿命。     

整体式橡胶履带用胶料抗切割性能的配方影响因素研究

研究主体材料、补强体系和硫化体系等配方因素对整体式橡胶履带用胶料抗切割性能的影响。结果表明,以并用比为80/20的天然橡胶/丁苯橡胶并用胶为主体材料,采用补强性好的炭黑与白炭黑并用补强体系,适当增大炭黑用量,采用普通硫黄硫化体系,添加适量抗硫化返原剂和抗撕裂助剂,有利于提高胶料的抗切割性能。     

补强体系对NR硫化胶疲劳破坏特性的影响

用断裂力学方法研究炭黑N330、炭黑N330/白炭黑和白炭黑补强NR硫化胶的疲劳破坏特性.结果表明,与炭黑N330和炭黑N330/白炭黑补强的NR硫化胶相比,白炭黑补强的NR硫化胶疲劳寿命较长,内部潜在缺陷较少,抗裂纹扩展性能较好;随着疲劳时间的延长,NR硫化胶拉断时的应变能密度减小;疲劳寿命方程能够快速、准确地预测NR硫化胶的疲劳寿命.     

耐寒耐油NBR的研制

研究了不同的硫化体系、补强体系、增塑体系,以及NBR与BR并用,对胶料的耐寒性、耐油性以及其他物理性能的影响。结果表明:采用DCP/硫黄复合硫化体系和高耐磨炭黑/喷雾发黑并用补强体系以及DOS/TP95并用增塑体系,并且在NBR胶料中并用BR,能有效兼顾耐寒性、耐油性,获得综合性能良好的胶料。     

天然橡胶制品抗疲劳性能的因素简析

本文分析了天然橡胶的分子链结构特征，简述橡胶材料疲劳老化后的破坏机理，并着重分析了配方中不同硫化体系、填充补强体系以及胶料的加工工艺对天然橡胶抗疲劳破坏性能的影响。     

炭黑在橡胶中的应用研究进展

介绍炭黑单用和与其他补强剂并用在天然橡胶和合成橡胶及其并用胶中的应用研究情况。炭黑品种、粒径、结构度和用量对天然橡胶、丁苯橡胶、顺丁橡胶、丁腈橡胶、三元乙丙橡胶、丁基橡胶及其并用胶性能影响较大,炭黑与白炭黑、硅土、碳纳米管和短纤维等并用具有协同效应。今后应继续研究有关炭黑的补强作用机理,尤其是新品种炭黑及其对新胶种的补强机理,开展炭黑与其他补强剂并用在橡胶中应用的研究,以进一步提高轮胎和橡胶制品性能,降低成本。     

天然橡胶疲劳性能的配方与工艺研究

研究了配方及加工工艺对天然橡胶疲劳性能的影响。结果表明：1）硫化体系对硫化胶疲劳寿命有显著影响,普通硫化体系抗疲劳性能最好,有效硫化体系抗疲劳性能最差;2）加入增硬剂可获得流动性好、疲劳性能优异的高硬度天然橡胶胶料;3）加工工艺对橡胶材料疲劳性能影响显著,采用密炼工艺,以升华硫磺替代沉淀硫磺,同时在胶料中加入适量的分散剂,可明显改善胶料中炭黑和配合剂的分散性,提高橡胶硫化制品的抗疲劳性能。     

高速工程机械轮胎基部胶配方的设计

介绍高速工程机械轮胎基部胶配方的设计。参比现有工程机械轮胎基部胶配方,生胶体系采用天然橡胶/顺丁橡胶并用胶,补强体系采用高耐磨炭黑/白炭黑并用体系,粘合体系采用间-甲-白体系,硫黄选用不溶性硫黄,试验配方胶料的300%定伸应力增大,拉伸强度相当,生热降低,自粘性提高,成品轮胎的高速和耐久性能提高。     

环保型硫化促进剂CBBS在橡胶中的应用研究

研究环保型硫化促进剂CBBS在天然橡胶(NR)和丁苯橡胶(SBR)硫黄硫化体系胶料中的应用。结果表明:在NR炭黑补强胶料中促进剂CBBS胶料具有硫化活性高、硫化平坦性好、交联程度大的特点,促进剂CBBS的炭黑/白炭黑并用补强胶料的硫化特性和硫化物物理性能较优;在SBR炭黑补强胶料中促进剂CBBS胶料具有焦烧时间长和加工安全性好的特点,促进剂CBBS的炭黑/白炭黑并用补强胶料的硫化速度较慢,但硫化胶物理性能优异。     

全钢子午线轮胎疲劳破坏现象仿真与优化设计研究

基于有限元的轮胎疲劳寿命评价方法,建立295/80R22.5全钢子午线轮胎的有限元模型。使用ABAQUS隐式分析方法获得轮胎的应变、应力以及应变能密度等基本参数后,根据轮胎实际使用中的破坏情况选择影响疲劳寿命的评价指标。结果表明:高速耐久工况下,应选择应变能密度和帘线张力作为影响疲劳寿命的评价指标,而且适当增加带束胶厚度能有效提高轮胎的疲劳寿命;低速重载工况下,应当选择帘线和橡胶间的剪应力(层间剪应力)作为影响疲劳寿命的评价指标,且适当降低胎体帘布层和补强层的高度能有效提高轮胎的疲劳寿命。     

Effect of the blooming of chemical curatives on the cyclic fatigue life of natural rubber filled with a silanized silica nanofiller

When partly soluble chemical curatives are mixed with raw rubber, they migrate to the rubber surface, which can be detrimental to the rubber properties. Two rubber compounds with different amounts of curatives were prepared by mixing natural rubber with a high loading of precipitated amorphous white silica nanofiller. The silica surfaces were pretreated with bis(3‐triethoxysilylpropyl)‐tetrasulfide coupling agent to chemically adhere silica to the rubber. The chemical bonding between the filler and rubber was optimized via the tetrasulfane groups of bis(3‐triethoxysilylpropyl)‐tetrasulfide by adding accelerator and activator. The rubber compounds were cured and stored at ambient temperature for up to 65 days. One compound showed extensive blooming as a function of storage time. The cyclic fatigue life of the rubber vulcanizates was subsequently measured at a constant strain amplitude and test frequency at ambient temperature. The blooming of the chemical curatives reduced the cyclic fatigue life of the rubber vulcanizate by more than 100%. The migrated chemical curatives produced a thin layer approximately 15 μm in size beneath the rubber surface. When the rubber was stressed repeatedly in the fatigue test, cracks initiated in this layer and subsequently grew, causing the fatigue life of the vulcanizate to decrease. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Evaluation of fatigue performance of filled and unfilled natural rubber/styrene-butadiene rubber composites

This paper deals with the fatigue life analysis of a blend of natural rubber (NR) and styrene-butadiene rubber (SBR) with and without nanoclay particles. Various damage parameters based on strain are investigated. A nonlinear finite element analysis is carried out by using ABAQUS. To formulate the life prediction models, the measured fatigue life is used together with various damage parameters. It is shown that all the damage parameters can estimate the fatigue lives effectively with correlation coefficients greater than 0.9. There is a good agreement between the obtained fatigue live predictions and the measured fatigue results. The effect of various parameters such as true strain and nanoparticles' loading is also investigated. The results of sensitivity analysis show that the strain has a greater effect on the variation of the rubber compounds' fatigue life. The test samples' fracture surface is assessed via scanning electron microscopy (SEM). SEM results show that as the strain increases, the test samples softly fail while the fracture surface of the nanocomposite is roughened by the addition of nanoclay.     

The fracture behaviour of a PXE/HIPS polyblend

As part of an overall examination of the fatigue crack propagation (FCP) behaviour of impact-modified polymers, a study of the fracture morphology of a PXE/HIPS polyblend polymer subjected to monotonic and cyclic loading conditions is reported. The HIPS rubbery-phase particles are found to fail by particle rupture in both fatigue and fast fracture. Another impact modifying addition, PE, is found to fail by a combination of interfacial rupture and tearing, the balance depending on the prevailing stress intensity value and the strain rate. Matrix failure is via multiple crazing at low fatigue crack growth rates, but shear yielding is believed to become a major fracture mechanism with increasing K. The degree of plastic deformation of the matrix increases with increasing strain rate. This fact is manifested by the increasing void size associated with the interfacial separation of the PE particles.     

Coupling effect of non-relaxing and high temperature on fatigue properties of carbon-black filled isoprene rubber

This paper presents an extensive experimental investigation on fatigue properties of carbon-black filled isoprene rubber under complex loadings. A basic life prediction model taking strain energy density as fatigue parameter is first proposed based on fatigue crack growth tests and uniaxial tension fatigue tests under relaxing loads at room temperature. A database of fatigue life including relaxing and non-relaxing is established through a great number of fatigue tests under five temperatures. Based on the database, two empirical parameters, that is, temperature factor (N_RT/N_HT) and life reinforcement factor (Re), are introduced to quantitatively characterize the coupling effects of high temperature and non-relaxing loads on fatigue life. The fatigue mechanisms under different conditions are compared via wide-angle x-ray diffraction tests and postmortem analysis. It reveals that the weakening of life reinforcement at high temperatures is closely related to the strain induced crystallization behavior of rubber.     

炼油焦化装置高压离心水泵轴断裂失效分析

某企业高压离心水泵发生断轴事故,对该高压水泵断轴进行材料化学成分、断口宏观形貌、金相组织以及断口腐蚀产物能谱等检验分析。结果表明,造成此次高压水泵断轴事故的主要原因是介质水中含有硫和氯,并在水泵的出口处聚集浓缩,使泵轴产生腐蚀凹坑,从而引起裂纹萌生,最终导致疲劳裂纹扩展,使泵轴发生断裂失效。     

断裂力学方法在橡胶复合材料疲劳研究中的应用

综述断裂力学方法在橡胶复合材料中的应用现状,着重介绍了撕裂能理论在预测疲劳裂纹增长速率以及预报疲劳寿命方面的应用。     

硅橡胶复合材料的多轴疲劳寿命计算及优化设计

基于裂纹扩展理论,采用Python语言开发了橡胶的多轴疲劳寿命算法并进行了试验验证,并计算了硅橡胶哑铃形单轴拉伸试样、平面拉伸试样及十字形等双轴拉伸试样的疲劳寿命;为兼顾硅橡胶复合材料的发电性能和疲劳寿命,采用总能量密度(PI)来评估复合材料的综合性能.结果表明,通过PI评估发现,等双轴拉伸下应变能密度(W)最大,开裂...     

The influence of cohesion and adhesion parameters on the fatigue life of hot mix asphalt

Fatigue cracking is one of the major distresses of hot mix asphalt (HMA) at moderate temperatures. Two of the main properties of asphalt mixtures affecting fatigue are the cohesive bond energy of asphalt binder and the adhesive bond energy between asphalt binder and aggregate. These two parameters were calculated using surface free energy (SFE) theory. Furthermore, the fatigue life of asphalt mixtures was measured by indirect tensile fatigue test. The results showed that asphalt mixtures with limestone aggregates, with the most specific surface area, and magnitude of adhesion had the highest fatigue life. Moreover, asphalt mixtures made with asphalt binder having the highest penetration had greater fatigue life than the other mixtures. The enhanced fatigue life was attributed to the greater cohesion energy and higher resistance to fatigue cracking in asphalt film. Also, these mixtures had the highest adhesion energy on the contact surface between asphalt binders and aggregates, which increased the energy required to separate the asphalt binder from the aggregate surface and the occurrence of adhesion rupture distress.