对橡胶材料流变模型的探讨

提出了一种新的橡胶材料流变模型。它是根据橡胶材料流变性能实验结果，经过数学推导得出来的。它跟以前的经验流体模型不同，每一项、每一个参数都具有较明确的物理意义，简单、明了地说明了橡胶材料的粘弹性本     

橡胶材料本构模型辨识方法改进

根据橡胶材料辨识的数学公式推导,利用MATLAB软件通过最小二乘法拟合建立一种橡胶材料本构模型辨识编程计算方法,并与Abaqus有限元分析软件辨识工具进行对比分析。结果表明,相对Abaqus软件辨识工具,该计算方法使用条件较简单,拟合精度较高,可以满足大多数单轴拉伸试验数据的辨识与仿真需求,证实了利用MATLAB程序进行橡胶材料辨识方法的优越性。     

基于Mooney-Rivlin模型和Yeoh模型的超弹性橡胶材料有限元分析

介绍橡胶材料两种常用的应变能密度函数模型--Mooney-Rivlin模型和Yeoh模型,并解析求得其材料常数.采用ANSYS有限元分析软件,分析比较两种模型的位移和应力云图,验证其适用性,即Mooney-Rivlin模型适合模拟中小变形行为;Yeoh模型适合模拟炭黑填充NR的大变形行为.     

计算机模拟在橡胶材料疲劳性能预测中的应用

橡胶是一种超弹性高分子性能的特殊材料,其具有独特的性能在受力的作用下不会出现永久形变,使其被广泛应用于仪器设备、管道衔接、汽车、航空机械等领域中。在实际使用中,橡胶产品由于特殊的材料性能,通常在机械的关键部位被广泛应用,但是必须要对其加强护理和保护,以防橡胶制品的失效给人们带来不可挽回的损失,所以,有必要分析和研究橡胶的疲劳性能。本文主要使用ABAQUS等有限元软件来预测和分析橡胶材料的疲劳寿命,在本文设计了实验流程,预测橡胶材料在使用过程中的疲劳性能,以对实验的可行性进行确定。     

基于Mooney-Rivlin和Yeoh模型的超弹性橡胶材料有限元分析

通过介绍橡胶材料两种常见的应变能密度模型--Mooney-Rivlin模型和Yeoh模型,解析求得其材料常数,并结合ansys有限元分析软件,比较两种模型的位移、应力云图,验证了它们的适用范围,对超弹性材料的有限元分析模型选用的总结,为这类材料的有限元分析和应用起到了指导作用.     

橡胶材料单轴拉伸疲劳寿命预测的有限元分析

应用Abaqus/CAE有限元分析软件模拟哑铃形橡胶试样在单轴拉伸载荷下的Mises应力和拉格朗日应变分布,提取节点处的数据作为原始数据,导入Matlab二次开发的橡胶疲劳寿命计算程序,得到材料各个节点的疲劳寿命,再利用Python语言将计算结果导回Abaqus/Visualization模块,得到橡胶材料疲劳寿命云图。分析结果与相关试验数据基本相符。     

基于Isight平台的橡胶材料超弹模型参数优化

超弹模型及参数的选择对于橡胶制品仿真计算结果的准确性有着重要的影响。对三元乙丙圆柱形橡胶试样进行单轴压缩实验,利用不同的超弹模型对实验值进行拟合,建立与实验条件一致的仿真模型,来判断不同超弹模型计算准确性。基于Isight优化平台,选择序列二次规划(NLPQL)算法对拟合的超弹模型参数进一步优化,利用优化后参数进行仿真计算。结果表明,优化参数仿真计算结果与实验值具有很好的一致性,其能够更准确地描述橡胶材料的超弹特性。     

基于细观力学的短纤维增强复合材料断裂性能数值研究

基于细观力学,采用虚拟裂纹扩展结合有限元法计算了短纤维增强复合材料纤维端部不同方向裂纹的应变能释放率,研究了网格尺寸对应变能释放率计算结果的影响,并分析应变能释放率随裂纹长度,纤维的长度、半径和含量的变化关系。研究表明:网格尺寸对应变能释放率的计算结果影响小;不同区域的裂纹,其应变能释放率受裂纹长度的影响不同;应变能释放率随裂纹扩展方向变化曲线呈对称特点,其中滑移型裂纹的扩展阻力较小;应变能释放率随着纤维长度、半径和含量的增大而增大。     

气膜润滑剪切机头及其在短纤维增强胶管中的应用

气膜润滑是挤出时在胶料和口型壁之间形成一层很薄的空气膜，不仅可以降低流动阻力，提高挤出量，同时也可降低挤出膨胀。在短纤维增强胶管挤出中可以通过内芯旋转使短纤维沿周向取向以提高爆破强度，但也因内芯旋转使挤出物扭转造成挤出不稳定。利用气膜润滑技术设计制造的气膜润滑剪切机头，成功地解决了由于内芯旋转而产生的挤出扭转造成的挤出不稳定现象。通过流场分析计算，从理论上预测了利用气膜润滑消除物料旋转的可行性。介绍了用气膜润滑剪切机头制造短纤维增强胶管的实验结果。     

光弹性法在橡胶材料应力分析中的应用

研究光弹性法在橡胶材料应力分析中的应用。以PU为模型材料，通过改变弹性模量调整橡胶材料刚度,再现实际加载过程中的应力情况，从光弹性等差线可快速、直观地找到材料的应力集中点，并可通过应力计算公式得到应力随载荷的变化。     

芳香族聚酰胺纤维增强丁腈橡胶垫片材料

研究了纤维含量、粘合处理方法、混炼胶薄通知出片因素对芳香族聚酰胺短纤维增强ＮＢＲ性能的影响。结果表明,芳香族聚酰胺短纤维的加入明显的ＮＢＲ的拉伸强度、撕裂强度和溶胀性能。密封性能测试结果表明,该材料可以代替石棉增强ＮＢＲ制作垫片,产品性能符合ＧＢ５３９－８３指标。     

Tear and processing behaviour of short sisal fibre reinforced styrene butadiene rubber composites

The tear failure and processing characteristics of short sisal fibre reinforced styrene butadiene rubber (SBR) composites were investigated. Tear strength was examined with special reference to the effects of fibre length, fibre orientation, fibre concentration and bonding agent. It was observed that the tear strength depends on all the above factors. The tear failure mechanism was analysed from fractographs taken using a scanning electron microscope (SEM). During tear testing, the composites failed by a shearing process. Microscopic examination of cracks propagating in SBR composites revealed that the amorphous SBR matrix developed cracks, leaving ligaments of rubber attached to the broken fibres. The rubber particles were stretched as the crack opened and failure occurred at large critical extensions. It was observed that an increase in the concentration of fibres increased the tear strength in both longitudinal and transverse directions. The tear strength values were almost three to four times higher than those of the unfilled vulcanizates under similar conditions. In order to analyse the processing behaviour, the green strength, mill shrinkage and Mooney viscosity of the compounds were determined. Finally, the polymer–filler interaction was studied using the Lorenz–Park and Kraus equations.     

木质纤维素短纤维在非轮胎橡胶制品中的应用

木质纤维素短纤维作为补强材料添加于橡胶中可提高未硫化胶的强度和挺性 ,降低挤出膨胀率 ,提高硫化胶的弹性模量、强度和硬度。用亚甲基接受体改性的Santoweb短纤维在胶料中的分散性很好 ,用于V带底胶和中低压胶管中已取得很好的效果。介绍了分别针对SBR、氯醚橡胶、EPDM、CPE、NBR和氟橡胶的适用木质纤维素短纤维规格及应用配方     

Microstructural characterization of short glass fibre reinforced polyethersulfone composites

To explore the effect of short glass fiber reinforcement (SGFR) on the mechanical properties of polyethersulfone (PES), microstructural characterization has been performed by positron lifetime technique. The free volume distribution of SGFR‐PES composites derived from CONTIN‐PALS2 program exhibits the narrow full width at half maximum (FWHM) indicates the strong interaction between polymeric chains of PES matrix and SGF. The positron lifetime parameters of SGFR‐PES composites are correlated with the mechanical properties viz., Tensile strength (TS), Young's modulus (YM) and elongation at break (EB). The decreased positron lifetime parameters, improved mechanical properties and reduced crystallinity of SGFR‐PES composites are attributed to the improved chemical and physical interaction between the functional groups of both SGF and PES matrix. This is clearly evident from the FTIR (Fourier Transform Infrared Spectrometry) studies. The hydrodynamic interaction parameter (h) show negative values, suggest the improved interaction in SGFR‐PES composites by the generation of excess friction at the interface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43647.     

Controlled orientation of short fibre reinforcement for anisotropic performance of rubber compounds

Abstract

The potential advantages of introducing anisotropic properties into a rubber compound by replacing some particulate filler with short fibre have been investigated. The control compound (containing no fibre) was based on NR and contained 60 pphr (N330) carbon black. In the fibre filled compound, 15 pphr of the carbon black was replaced with an equivalent volume of Santoweb fibre (10 pphr). Specimens with strong fibre orientation were produced and tensile, tear, compression, and shear properties measured at different angles to the orientation. Stretching parallel to fibre orientation resulted in a stiffness at low elongations × 3·5 higher than in the control compound. However, the tensile and tear strengths were lower than the control compound, probably owing to the high stresses at the fibre surfaces leading to fibre pullout. Maximum tensile and tear strengths were obtained when fibre orientation was at angles of 20° and 45°, respectively, to the stretching direction. Stiffness at a small (5%) compression was greater when fibres were oriented parallel to the compression direction. At greater compressions, fibre buckling reduced the stiffening effect. When fibres were oriented at 45° to the plane of shearing, shear stiffness in one direction was twice the shear stiffness in the opposite direction and twice the value for the control compound. Together with greater stiffness, this orientation led to low heat loss during dynamic shearing at a particular stress amplitude (40% of the value for the control compound).     

未来碳纤维复合材料的五大新市场

目前美国正在开发的碳纤维复合材料的五大新市场，是推动今后碳纤维及其复合材料大发展的动力。本文介绍了碳纤维在清洁能源车辆领域、土木建筑工程、近海油田开采、风力发电用大型叶片及高尔夫球杆等方面的应用前景及需求量预测     

Integrated compounding and injection moulding of short fibre reinforced composites

Abstract

Composites of high density polyethylene (HDPE) and carbon fibre (C fibre) were compounded and moulded into tensile test bars in compounding injection moulding (CIM) equipment that combines a twin-screw extruder and an injection moulding unit. Two HDPE grades exhibiting different rheological behaviours were used as matrices. The mechanical properties of the moulded parts were assessed by both tensile and impact tests. The respective morphologies were characterised by scanning electron microscopy (SEM) and the semicrystalline structures of the matrices investigated by X-ray diffraction. The final fibre length distribution and fibre orientation profiles along the part thickness were also quantified. The composites with lower viscosity exhibit higher stiffness, higher strength and superior impact performance. Both composites exhibit a three layer laminated morphology, featuring two shell zones and a core region. Interfacial interaction is favoured by a lower melt viscosity that enhances the wetting of the fibre surfaces and promotes mechanical interlocking. The composites display a bimodal fibre length distribution that accounts for significant fibre length degradation upon processing. The dimensions of the transversely orientated core differ for the two composites, which is attributed to the dissimilar pseudoplastic behaviour of the two HDPE grades and the different thermal levels of the compounds during injection moulding. Further improvements in mechanical performance are expected through the optimisation of the processing conditions, tailoring of the rheological behaviour of the compound and the use of more adequate mould designs.     

Effect of Nicalon SiC fibre heat treatment on short fibre reinforced β-sialon ceramics

SiC Nicalon fibre yarn was heat-treated at elevated temperature in a gas pressure furnace under CO atmosphere. Weak surface coating is essential for ceramic matrix composite (CMC) reinforcement. Therefore Nicalon SiC fibres were coated after CO heat treatment and then used for β-sialon ceramic reinforcement. The heat treated fibres were chopped about 1–2 mm, and β-sialon z = 1 starting powders were prepared with conventional ball milling. The sialon starting composition and the short fibres were mixed with the certain amount of water to obtain a plastically formable mud. This mud was unaxially cold-pressed to form green bodies and to decrease water content. The green bodies were hot pressed at elevated temperatures for half an hour to produce CMC samples. Vickers hardness test showed that heat-treated fibre reinforcement of β-sialon composites provided higher fracture toughness. Uniform fibre distribution, fibre coating, matrix densification and phase transformation were examined by SEM and XRD analysis.     

碳纤维增强氯丁橡胶复合材料的制备及性能

用碳纤维（CF）作增强相、氯丁橡胶（CR）作基相及硅烷偶联剂作相容剂,制备了CF/CR复合材料,考察了CF用量、硅烷偶联剂的种类及用量、硫化条件对复合材料热老化前后性能的影响,并用扫描电子显微镜（SEM）和傅里叶变换红外光谱（FTIR）仪对其结构进行了表征。结果表明,制备CF/CR复合材料的最佳配方为:CR 100份,CF 12份,KH 550 2.5份;最佳硫化条件为:温度175℃,压力10 MPa,时间30 min。SEM和FTIR分析表明,KH 550处理的CF比未处理及用Si 69处理的CF与CR的相容性更好。     

氧化石墨烯增强有机硅橡胶复合泡沫材料的性能

以甲基乙烯基硅橡胶（MVQ）为基质,以氧化石墨烯（GO）为增强剂和阻燃剂,制备了有机硅橡胶复合泡沫材料,考察了GO用量对复合泡沫材料力学性能及阻燃性能的影响。结果表明,随着GO用量的增加,有机硅橡胶复合泡沫材料的密度增大,拉伸性能和压缩性能提高,极限氧指数（LOI）增大,熔滴现象和发烟现象减弱。当GO用量为5份时,与纯MVQ相比,复合泡沫材料的拉伸强度提高了6.6倍,撕裂强度提高了4.7倍,压缩强度（50%形变）提高了12.3倍,LOI由22.3%提高至26.5%,且未发生熔滴和发烟现象,阻燃性能显著提高。