纤维帘线/橡胶复合材料的压缩性能

对纤维帘线／橡胶复合材料进行了压缩性能试验，结果表明帘线体积分数是影响纤维帘线／橡胶复合材料压缩性能的主要因素，帘线的类型、规格、结构性能对纤维帘线／橡胶复合材料的抗弯曲能力也有明显影响。     

子午线轮胎有限元分析 第4讲帘线-橡胶复合材料

帘线-橡胶复合材料是一种较为特殊的复合材料,在橡胶制品中有着广泛的应用,尤其是在轮胎中起着重要的作用。橡胶起密封气体、提供轮胎与地面抓着力的作用,帘线则承担大部分负荷。二者结合构成性能优异的帘线-橡胶复合材料。子午线轮胎的材料主要有两种:一种是纯胶料材料,包括胎     

橡胶帘线粘合性能在动态及加热条件下的评价方法

橡胶-帘线(包括钢丝帘线)复合材料在动态条件下粘结界面发生物理化学变化,直接影响材料使用性能。介绍橡胶-帘线动态剪切粘合试验基本原理:将帘线埋于方块硫化橡胶试样中,帘线两端悬以质量不同的砝码。试验时橡胶试样以一定的振幅和频率沿帘线伸延方向做往复运动,考察帘线与橡胶达到某一设定的粘合强度值所需的时间,用以表征帘线与橡胶在动态条件下的粘合性能。应用该原理和实用仪器对不同材质橡胶-帘线粘合性能做出测试和评价。     

单向帘线增强橡胶复合材料在疲劳过程中的温升

哈尔滨工业大学刘宇艳等人以单向帘线增强橡胶复合材料为研究对象 ,利用自行建立的疲劳试验系统 ,研究了周期载荷作用下橡胶复合材料表面温升的一般规律 ;讨论了实际热生成对材料疲劳行为的影响。为评价轮胎疲劳特性提供了有效的手段。《宇航材料工艺》 ,1 999,(5) :3 0单向帘线增强橡胶复合材料在疲劳过程中的温升     

试验频率和温度对橡胶/纤维帘线复合材料动态粘合性能的影响

研究试验频率和温度对橡胶/纤维帘线复合材料动态粘合性能的影响,并通过扫描电镜分析粘合失效后纤维帘线的表面形貌。结果表明,降低试验频率和提高试验温度会加速橡胶/纤维帘线复合材料的粘合失效,这主要是由橡胶基体的破坏以及橡胶与纤维帘线的界面脱粘引起的。     

子午线轮胎有限元分析 第6讲子午线轮胎的有限元分析模型

子午线轮胎的材料和结构都比较复杂,又有非线性的特点,给轮胎有限元分析带来非常大的困难。轮胎的橡胶材料具有大变形和近似不可压缩的超弹性。帘线-橡胶复合材料实质上是由作为增强相的帘线在基体相橡胶中排列组成的刚柔相辅的复合材料,呈现明显的各向异性。对子午线轮胎而言,     

轮胎帘线-橡胶复合材料的疲劳(四)

<正>(接上期)4.2.2.3帘线角度的影响在帘线角度影响的分析中也发现了所观察到的与导致帘线-橡胶叠层复合材料具有较短疲劳寿命有关的相关性。帘线角度增加会减小层间剪切应变(图10和图41),但会同时降低斜裁帘线-     

橡胶复合材料在循环载荷下的疲劳损伤特性

利用自行建立的疲劳试验系统，以单向聚酯帘线增强橡胶复合材料为对象，研究了循环载荷作用下影响橡胶复合材料疲劳性能的因素。结果表明，应力幅值和加载频率对橡胶复合材料疲劳性能影响较大，而平均应力影响较小。聚酯／橡胶复合材料的疲劳强化现象主要与组分材料本身的特性有关。     

单向聚酯帘线/橡胶复合材料的疲劳损伤机理

利用较Ｘ射线技术和扫描电子显微镜技术,研究了在周期载荷下单向聚酯帘线／橡胶复合材料的疲劳机理。结果表明,在高应务下,单向聚酯帘线／橡胶复合材料的疲劳损伤以聚酯帘线断裂为主,在中应力下,单向聚酯帘线／橡胶复合材料的疲劳损伤是逐步进行的;在你力下,单向聚酯帘线／橡胶复合材料的疲劳损伤仅有局部的界面损伤。     

纤维骨架材料技术讲座第5讲 纤维骨架材料对橡胶制品性能的影响

1　纤维骨架材料对轮胎性能的影响1 1　动态模量和损耗因子在行驶运转的轮胎中 ,增强帘线经受反复的拉伸、压缩、弯曲和扭转等多种应力的作用 ,有些作用还是周期性的。合成纤维帘线是高分子材料 ,其力学行为属粘弹性。在线性粘弹行为范围内 (帘线的应变幅度小于 1 % ) ,轮胎的滚动阻力和燃油消耗与增强帘线的动态模量 (Ｅ )和损耗因子(ｔａｎδ)有直接关系。动态模量与贮存模量 (或弹性模量 ,Ｅ′)和损耗模量 (Ｅ″)的关系如下 :Ｅ′=Ｅ ｃｏｓδＥ″=Ｅ ｓｉｎδ式中δ为滞后相角。曾有研究认为 ,与橡胶对轮胎滚动阻力的贡献相比 ,增强帘…     

Fatigue crack initiation and damage characterization in Brazilian test specimens for adhesive joints

The present study is focused on the fatigue failure initiation at bimaterial corners by means of a configuration based on the Brazilian disc specimens. These specimens were previously used for the generalized fracture toughness determination and prediction of failure in adhesive joints, carried out under static compressive loading. Under static loading, local yielding effects might affect the asymptotic two-dimensional linear elastic stress representation under consideration. Fatigue loading avoids this fact due to the lower load levels used. The present tests were performed using load control; video microscopy and still cameras were used for monitoring initiation and crack growth. The fatigue tests were halted periodically and images of the corner were taken where fatigue damage was anticipated. Damage initiation and subsequent crack growth were observed in some specimens, especially in those which presented brittle failure under static and fatigue tests. These analyses allowed the characterization of damage initiation for a typical bimaterial corner that can be found in composite to aluminium adhesive lap joints.     

Fabrication process and mechanical properties of C/SiC corrugated core sandwich panel

Carbon fiber reinforced SiC composite is a kind of promising high-temperature thermal protection structural material owing to the excellent oxidative resistance and superior mechanical properties at high temperatures. In this work, a novel design and fabrication process of lightweight C/SiC corrugated core sandwich panel will be proposed. The compressive and three-point bending of the C/SiC corrugated sandwich panels are conducted by experiment and numerical simulation. The relative density of as-prepared C/SiC sandwich panel and the density composite material are 1.1 and 2.1 g/cm³, respectively. As the density of the C/SiC sandwich panel is only 52.3% of the bulk C/SiC, suggesting that lightweight characteristic is realized. Moreover, the C/SiC sandwich panel manifests itself as linear-elastic behavior before failure in compression and the strength is as high as 15.1 MPa. The failure mode is governed by the core shear failure and panel interlayer cracking. The load capacity under the three-point bending C/SiC composite sandwich panel is 1947.0 N. The main failure behavior is core shear failure. The stress distribution under the compression and three-point bend was simulated by FE analysis, and the results of numerical simulations are in accordance with the experimental results.     

复合材料-木塑组合柱轴心受压性能试验研究

以木塑复合材料、无碱玻璃纤维织物以及不饱和聚酯树脂为原料,采用真空导入工艺制造复合材料-木塑组合柱。对该组合柱进行轴心受压试验,得到其失效模式、承载力以及纵向变形等力学行为。试验结果表明:复合材料-木塑组合柱在轴压荷载作用下,主要破坏模式为轴向受压破坏,且在复合材料面层出现横向裂纹;组合柱极限承载力随着截面尺寸的增加而显著提高,而且组合柱具有良好的延性。采用考虑组合效应的分析方法对该组合柱的轴压承载力进行预测,结果表明当组合系数取0.3时,理论计算结果与试验结果吻合较好。     

Evaluating the heat resistance of thermal insulated sandwich composites subjected to a turbulent fire

The fire structural response of sandwich composite laminates incorporating bio‐derived constituents subjected to a turbulent flaming fire was investigated. Fire structural tests were conducted on thermal insulated sandwich composites incorporating a thin surface‐bonded non‐woven glass fibre tissue impregnated with char‐forming fire retardant, ammonium polyphosphate. The sandwich composite laminates were loaded in compression at 10%, 15% or 20% of the ultimate compressive strength while simultaneously subjected to turbulent flames imposing an incident heat flux of 35 kW/m². Generally, the failure time increased with the reduced applied compressive load. The thermal insulated sandwich composite laminates had considerably improved fire resistance in comparison to their unmodified counterparts. The unmodified composites failed 96 s earlier than the thermal insulated specimens when the compression load was 10% of the ultimate compressive strength. The presence of ammonium polyphosphate at the heat‐exposed surface promoted the formation of a consolidated char layer, which slowed down heat conduction into composite laminate substrate. The fire reaction parameters measured via the cone calorimeter provided insights into the thermal response hence fire structural survivability of sandwich composite laminates. Copyright © 2015 John Wiley & Sons, Ltd.     

Strength of a Hi-Nicalon™/Silicon-Carbide-Matrix Composite Fabricated by the Multiple Polymer Infiltration-Pyrolysis Process

A woven-fabric Hi-Nicalon™-fiber reinforced SiC-matrix composite has been fabricated by using a multiple polymer infiltration-pyrolysis (PIP) process. The three-point bend strength, at room temperature, of the composite is examined as a function of total porosity of the composite. The porosity of the composite decreases as the number of PIP cycles ( N ) increases. Both the proportional-limit load and the maximum load in the three-point bend test increase as N increases. A compressive fracture mode is observed for N < 10 (total porosity of >10%), and a tensile fracture mode is observed for N greaterthan equal to 10 (total porosity of lessthan equal to10%). For the composite with N = 14, with a total porosity of 8 vol%, a proportional-limit stress of 410 MPa and a maximum stress of 600 MPa are achieved.     

Mechanical behaviors of four‐step 1 × 1 braided carbon/epoxy three‐dimensional composite tubes under axial compression loading

This article focuses on the quasistatic axial compression behavior and the consequent energy absorption of three different types of carbon/epoxy braided composite tubes. The focus is to evaluate the effect of sample length and braiding angle on the energy absorption and failure mechanism of the braided composite tubes. All tubes were manufactured with carbon fiber through four‐step 1 × 1 braiding process and epoxy resin. Quasistatic axial compression tests were carried out to comprehend the failure mechanism and the corresponding compressive load–displacement characteristics of each braided composite tube. The quasistatic compression test parameters such as the compression peak load and the energy absorption of all these composite tubes were compared. It was found that as the length of the sample increased, the peak load reduced and the energy absorption of the braided tubes at 45° braiding angle was considerably higher than that of other braiding angles of 25° and 35°. The failure modes included matrix crack along the braiding angle, fiber breakage, bulging and debonding between yarns. POLYM. COMPOS., 37:3210–3218, 2016. © 2015 Society of Plastics Engineers     

The bond of near-surface mounted reinforcement to low-strength concrete

This paper focuses on the bond between near-surface mounted (NSM) reinforcement and low-strength concrete. In order to investigate this, eight beams made of low-strength concrete were made. The compressive strength of this concrete varied from 14.22?MPa to 16.83?MPa. These beams were then tensioned under monotonic loading until failure. The test setups differed in terms of their groove size and the type of reinforcement (a rod and plate of carbon fiber reinforced polymer, prestressing steel). Based on the achieved results and analysis, it was found that the NSM method can be applied to low-strength concrete. Furthermore, the application of a NSM reinforcement rod and plate, made of the carbon fiber reinforced polymer, and prestressing steel showed a satisfactory bond strength when compared to low-strength concrete. However, the carbon plates performed better in terms of failure load and rate use than the rods made of carbon and the prestressing steel. Moreover, the results showed that the increase of groove size for the near-surface mounted reinforcement made of prestressing steel did not have an effect on the failure mode. In addition, a significant increase of the failure load was observed for the prestressing steel. Finally, the effect of concrete strength was analyzed and compared with the results found in literature.     

Mechanical properties of carbon nanofiber/fiber-reinforced hierarchical polymer composites manufactured with multiscale-reinforcement fabrics

Hierarchical polymer composites – defined as carbon nanofiber/fiber-reinforced polymer composites – were manufactured using multiscale-reinforcement fabrics (MRFs) and they were characterized for their mechanical properties. The MRFs were fabricated by electrophoretic deposition of carboxylic acid- or amine-functionalized carbon nanofibers (CNFs) on the surface of sized or unsized carbon fiber layers. Compared to the base composite (not containing CNFs), the hierarchical composites containing the functionalized CNFs showed an increase in interlaminar shear strength (ILSS) and compressive strength. Panels containing amine-functionalized CNFs had the highest increase in properties: 12% in ILSS and 13% in compressive strength. The reinforcement mechanism was also investigated with emphasis placed on the fiber/matrix interface and the load transfer between matrix, CNFs, and carbon fiber.     

The compressive and tensile behavior of a 0/90 C fiber woven composite at high strain rates

An investigation into the compressive and tensile behavior of a carbon fiber reinforced resin matrix composite at high strain rates is carried out using a split Hopkinson bar. All the dynamic tests are performed under the condition of stress equilibrium and constant strain rate. The results of the compressive tests show that the failure strength and strain of the composite increase with the increase of strain rate. A plateau is observed in a typical stress–strain curve which prompts further study into the failure mechanism by monitoring the failure process with a high-speed camera. The three-phase failure mechanism of on-impact compression, crack-induced unloading, and crack deviation-caused further condensation, is found to have greatly increased the strength and toughness of the composite. In the tensile tests, an increase of strain rate produces a reduced fracture angle and extended crack path. In this process, more failure energy is absorbed, thus the failure strength and strain of the composite are improved. The Cowper–Symonds model of strain rate dependency indicates that the material has a higher tensile strength than compressive strength, and the strain rate sensitivity is more noticeable at high stain rates than quasi-static conditions.     

Melt processing and mechanical property characterization of multi-walled carbon nanotube/high density polyethylene (MWNT/HDPE) composite films

High density polyethylene (HDPE) was used as the matrix material for a carbon nanotube (CNT) polymer composites. This combination of composite constituents has not been previously reported in the literature. Multi-wall carbon nanotube (MWNT)/HDPE composite films were fabricated using the melt processing method. The composite films with 0, 1, 3 and 5% nanotube content by weight were analyzed under SEM and TEM to observe nanotube dispersion. The mechanical properties of the films were measured by small punch test. Results show increases in the stiffness, peak load and work to failure for the composite films with increasing MWNT content.