孔隙率对复合材料单向板横向力学性能的影响

在考虑纤维和孔隙随机分布的情况下,通过随机算法生成包含孔隙的代表性体积单元Representative Volume Element(RVE)。对生成的RVE建立有限元模型,引入基体的塑性本构模型和界面的双线性本构模型,采用有限元方法研究了孔隙率对碳纤维/环氧树脂复合材料单向板横向力学性能的影响。研究显示,孔隙随机分布对横向力学性能的影响不是很大;当孔隙率不超过临界值时,孔隙对横向力学性能的影响相对较小;当孔隙率超过临界值后,材料横向弹性模量、横向拉伸强度和横向压缩强度都会有较大的下降。     

连续玄武岩纤维及其复合材料研究

通过连续玄武岩纤维的成分对其性能的影响分析,连续玄武岩纤维的拉丝成纤工艺对其性能的影响研究以及当前我国最具代表性的横店集团上海俄金玄武岩纤维有限公司玄武岩复合材料的性能研究,得出了我国现阶段连续玄武岩纤维的研制发展水平,并对未来我国连续玄武岩纤维的发展进行了展望.     

玄武岩纤维多轴向经编增强复合材料力学性能研究

以玄武岩纤维多轴向经编织物为增强体,以环氧树脂为基体,通过真空辅助树脂传递模塑(VARTM)工艺,实现复合材料成型。分别测试玄武岩纤维的单轴向、双轴向、四轴向经编复合材料沿0°和90°方向的拉伸、弯曲性能,并对断裂后的图像及试验数据进行对比分析。最终确定了玄武岩纤维的三种轴向经编复合材料沿0°方向双轴向拉伸强度比四轴向高28. 13%,弯曲强度比四轴向高10. 59%,沿90°方向单轴向拉伸强度比双轴向高22. 94%,比四轴向高58. 64%,弯曲强度比双轴向高21. 02%,比四轴向高63. 46%。     

玄武者纤维及其复合材料的研究进展

对玄武岩纤维的组成成分和性能进行了总结,对玄武岩纤维在国内外的研究进展及玄武岩纤维水泥基复合材料、玄武岩纤维沥青基复合材料、玄武岩纤维树脂基复合材料、玄武岩纤维与其他纤维的复合材料在各领域的研究和应用状况进行了概述。     

基体中含有随机分布裂纹的纤维增强复合材料的总体弹性常数

本文应用自洽方法计算了含随机分布裂纹的基体的等效弹性常数,然后利用GMC方法计算了复合材料的总体弹性常数.结果表明,随着裂纹密度的增加,基体的等效弹性模量和泊松比会降为零;而同时,复合材料的纤维方向的弹性模量的下降,但是仍然能达到没有裂纹时的90%.这表明当基体完全破坏的时候,纤维仍能够在纵向承受载荷.另外,当基体的等效弹性模量和泊松比会降为零时,复合材料的横向弹性模量和剪切模量都接近为零,表明这时复合材料无法承受横向的拉压力和剪切力.     

玄武岩纤维增强聚乳酸力学性能及耐老化性能

通过拉伸实验和老化实验,研究了玄武岩纤维含量对BF/PLA拉伸性能、抗冲击性能及耐老化性能的影响规律,通过DSC实验得到BF/PLA复合材料的结晶度,分析其耐老化原因。随着质量分数增加,其拉伸强度增加可达到141 MPa,弹性模量达到5 GPa,达到峰值后又减小。质量分数达到30%时,缺口冲击强度和非缺口冲击强度分别达到6.7 kJ/m~2和20.76 kJ/m~2。DSC实验结果表明,随着玄武岩纤维含量的增加,聚乳酸复合材料的结晶度由34.6%增加到54.6%,而结晶度的增加可以减缓聚乳酸的降解速度。当质量分数达到60%时,老化实验后的弹性模量可以保持降解前的77%,延缓降解速度较为明显。经分析,拉伸强度与玄武岩纤维质量分数呈二次多项式关系,而弹性模量与玄武岩纤维质量分数之间呈线性关系。这种函数关系不受材料力学性能下降的影响。     

玄武岩纤维及其增强水泥基复合材料研究进展

玄武岩纤维是一种新型无机绿色环保高性能纤维材料.综述了玄武岩纤维及其玄武岩纤维增强水泥基复合材料(basalt fiber reinforced cement-based composite)国内外最新研究进展,简要介绍了玄武岩纤维国内外研究进展,玄武岩纤维表面处理技术对界面性能的影响以及对提高复合材料整体性能的必要性,并重点介绍了玄武岩纤维增强水泥基复合材料力学性能研究和纤维增强机理以及玄武岩纤维水工混凝土及BFRP加固应用.最后对玄武岩纤维增强水泥基复合材料的发展研究方向进行了展望.     

连续玄武岩纤维在复合材料中应用

连续玄武岩纤维是绿色环保材料,是国家鼓励开发与应用的纤维材料。本文对玄武岩基本情况和连续玄武岩纤维制作等工艺的介绍,根据连续玄武岩纤维的特点,列举出玄武岩纤维长纤增强LFT、玄武岩直接无捻粗纱增强纤维和玄武岩纤维SMC无捻粗纱增强纤维的应用特点和情况,并对连续玄武岩纤维复合材料作了展望,期待有更大的应用范围。     

激光改性玄武岩纤维性能研究

采用高能激光束对玄武岩纤维进行表面改性,并制备玄武岩纤维/环氧树脂复合材料。利用扫描电镜、原子力显微镜、X射线衍射等手段,表征改性前后玄武岩纤维的微观形态、物相结构,系统研究了激光对纤维的微观组织变化、性能等影响规律,并测试了玄武岩纤维/环氧树脂复合材料的力学性能。研究结果表明,随着激光功率的增加,玄武岩纤维表面缺陷深度和缺陷面积增加。当激光功率由0 W提高至120 W时,表面缺陷最大深度由9 nm增加至180 nm,表面缺陷的分布范围由3.5~6.5 nm增加至90~120 nm,表面粗糙度由1.41 nm增加至24.70 nm。激光改性后,玄武岩纤维单丝拉伸性能降低,由于激光对纤维的辐射作用,玄武岩纤维的表面缺陷深度与拉伸强度的关系不符合经典理论。激光改性前后,玄武岩纤维XRD谱峰位基本一致,表面所含元素的种类没有发生变化。激光改性使玄武岩纤维/环氧树脂复合材料的力学性能有所改善,随着激光功率的增加,复合材料的拉伸强度和冲击强度呈先升高后降低的趋势。     

玄武岩纤维增强聚乳酸力学性能及耐老化性能

通过拉伸实验和老化实验，研究了玄武岩纤维含量对BF/PLA拉伸性能、抗冲击性能及耐老化性能的影响规律，通过DSC实验得到BF/PLA复合材料的结晶度，分析其耐老化原因。随着质量分数增加，其拉伸强度增加可达到141 MPa，弹性模量达到5 GPa，达到峰值后又减小。质量分数达到30%时，缺口冲击强度和非缺口冲击强度分别达到6.7 kJ/m²和20.76 kJ/m²。DSC实验结果表明，随着玄武岩纤维含量的增加，聚乳酸复合材料的结晶度由34.6%增加到54.6%，而结晶度的增加可以减缓聚乳酸的降解速度。当质量分数达到60%时，老化实验后的弹性模量可以保持降解前的77%，延缓降解速度较为明显。经分析，拉伸强度与玄武岩纤维质量分数呈二次多项式关系，而弹性模量与玄武岩纤维质量分数之间呈线性关系。这种函数关系不受材料力学性能下降的影响。     

钢丝-连续玄武岩纤维复合板及其力学性能研究

简易制作了钢丝一连续玄武岩纤维复合板试件及其单向拉伸试验装置,通过单向拉伸试验,测试分析了该复合板的力学性能。结果表明钢丝一连续玄武岩纤维复合板具有较好的力学性能：当试样钢丝体积分数为20．6％时,其复合板弹性模量为99．8GPa,比纯CBF复合板试样提高12．9‰且抗拉强度也提高9．6％;同时成本降低35‰因此是一种高性价比的加固材料。     

盐冻作用下玄武岩纤维混凝土力学性能损伤研究

针对西北寒旱地区混凝土结构易开裂耐久性降低的问题,选取力学性能优异的玄武岩纤维作为混凝土增强材料,采用室内快速冻融试验,以纤维体积掺量为变量,研究了不同纤维体积掺量(0.05%、0.1%、0.15%、0.2%)混凝土试件分别在清水、质量分数为3%的NaCl溶液、质量分数为5%的Na₂SO₄溶液冻融作用下动弹性模量、抗压强度、抗折强度三个力学性指标的变化。研究发现,玄武岩纤维的掺入能有效提升混凝土的初始抗折强度和抗盐冻能力,纤维体积掺量在0.15%~0.2%时混凝土试件动弹性模量、抗压强度与抗折强度在盐冻作用下的衰减速率减缓明显,玄武岩纤维混凝土在三种冻融介质中力学性能下降速率排序为清水<5%Na₂SO₄溶液<3%NaCl溶液。以动弹性模量为损伤变量,拟合混凝土相对抗压强度、相对抗折强度与损伤度的相关模型,模型相关性良好。研究结果可为玄武岩纤维混凝土的实际运用与后期维护提供理论依据与参考。     

玄武岩纤维混凝土耐高温性能分析

对不同玄武岩纤维体积率混凝土进行室内高温试验,总结与分析了温度和纤维体积率对混凝土立方体抗压强度、劈裂抗拉强度和静弹性模量的影响规律。研究结果表明:玄武岩混凝土的抗压强度、抗拉强度和弹性模量均在200℃高温出现拐点,200℃高温后玄武岩纤维混凝土的力学性能均出现不同程度的降低;混凝土的力学性能随玄武岩纤维体积率的增大而呈现出先增大后减小的趋势,最优的玄武岩纤维体积率为0.15%;玄武岩再生混凝土的力学性能随再生骨料取代率的增大而减弱,再生骨料取代率不宜大于30%。     

Elastic Properties of Laminated Calcium Aluminosilicate/Silicon Carbide Composites Determined by Resonant Ultrasound Spectroscopy

The elastic properties of unidirectional and 0°/90° crossply Nicalon-SiC-fiber-reinforced calcium aluminosilicate (CAS/SiC) ceramic-matrix composites have been measured using a resonant ultrasound spectroscopy (RUS) technique. This approach has allowed the nondestructive determination of the complete set of independent second-order elastic stiffness constants of these ceramic composites. These stiffness data have been used to obtain the orientation dependence of Young's modulus and the shear modulus. The results are in reasonably good agreement with the limited experimental data obtained from mechanical testing. The RUS measurements reveal that the unidirectional CAS/SiC composite is well modeled by transverse isotropic symmetry, indicating relatively isotropic fiber spacing in the transverse plane. The analysis indicates that the overall elastic anisotropy is also small for unidirectional and 0°/90° laminated CAS ceramic-matrix composites, a result that can be attributed to the relatively low modulus ratio of the Nicalon SiC fiber to the CAS matrix and to the moderate fiber volume fraction.     

Characterizing elastic properties of carbon nanotube‐based composites by using an equivalent fiber

Effective elastic properties for carbon nanotube (CNT)‐reinforced composites are obtained through a variety of micromechanics techniques. An embedded CNT in a polymer matrix and its surrounding interphase is replaced with an equivalent fiber for predicting the mechanical properties of the CNT/polymer composite. Formulas to extract the effective material constants from solutions for the representative volume element under three loading cases are derived based on the elasticity theory. The effects of an interphase layer between the nanotubes and the polymer matrix as result of effective interphase layer are also investigated. Furthermore, this research is aimed at characterizing the elastic properties of CNTs‐reinforced composites using Eshelby–Mori–Tanaka approach based on an equivalent fiber. The variations of mechanical properties with tube radius, interphase thickness, and degree of aggregation are investigated. It is shown that the presence of aggregates has stronger impact than the interphase thickness on the effective modulus of the composite. This is because aggregates have significantly lower modulus than individual CNTs. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers     

On the Effect of Fiber Shape and Packing Array on Elastic Properties of Fiber-Polymer-Matrix Composites

Abstract

In this study, three-dimensional finite element simulations on the base of the cell model and micromechanics are made to predict effective elastic properties of fibrous composites. The effects of fiber shape, packing array and volume fraction on the overall elastic behavior of an epoxy resin containing unidirectional glass fibers are examined. The geometrical structure includes three types of periodic fiber arrangements in cubic, hexagonal and rectangular cells. The fibers are assumed to be of four shapes; square, circular, elliptic and rectangular. The numerical results indicate that the overall transverse elastic properties are rather sensitive to both fiber shape and packing array while fiber geometry has no effect on the apparent overall Young's modulus in the longitudinal direction of the fibrous composite.     

Finite element analysis and experiment study on the elastic properties of randomly and controllably distributed carbon fiber-reinforced hydroxyapatite composites

Randomly distributed carbon fiber-reinforced hydroxyapatite (RCF/HA) and controllably distributed carbon fiber-reinforced hydroxyapatite (CCF/HA) composites were firstly studied to design and prepare different required composite artificial bones with satisfying mechanical properties by combining experiment approach, theoretical prediction and finite element analysis (FEA). A plug-in was obtained by secondary development of ABAQUS for the FEA. A 3D representative volume element (RVE) for RCF/HA and CCF/HA can be easily generated using this tool. Stress and strain analyses of three directions of RVE were performed by ABAQUS with different fiber mass fractions and distributions. The elastic modulus of CF/HA composites were obtained. With 0.2 wt% fiber, the elastic modulus of RCF/HA and CCF/HA composites increased by 6.31% and 54.4% compared with that of HA, respectively. For CCF/HA composites, the elastic modulus increased significantly with the increasing fiber mass fraction in the E₁₁ of the fiber. The results of experiment study and theoretical prediction were consistent with that of FEA. The maximum error between the FEA and experiment study was 2.84%, which confirmed that the RVE model was rational and accurate. The results indicated the fiber distribution can greatly affect the elastic modulus of the composites. In the future study, the controllably distributed fiber–reinforced composites would be a good choice because they can improve the mechanical properties as required. This study would endow possibility of designing and preparing the CF/HA bio-ceramics with satisfied mechanical properties by FEA and proper preparation parameter. It would also speed up application of clinical practice for CF/HA composites.     

含界面随机骨料三相增强复合材料的模型构建与有效力学性能预测

利用AUTOCAD绘制不同粒径的骨料随机分布于脆性基体的几何模型,导入ANSYS系统进行网格划分,建立有限元计算的特征体积单元;运用均匀化理论,计算了由随机骨料、基体和黏结层组成的三相复合材料的等效弹性模量,分析了随机颗粒的形状、粒径大小、分布特征、弹性模量以及基体弹性模量等的变化对复合材料力学性能的影响。该方法能够快速方便地建立复杂的几何模型并较真实地反映骨料的实际分布特征,较精确预测复合材料的有效力学性能。     

Multi‐scale modelling of the tensile behavior of lithium ion battery cellulose separator

As a satisfactory green material for a lithium ion battery separator, cellulose possesses better wettability and superior thermal and chemical stability compared to commercial polyolefin separators. The macroscopic mechanical properties of the separator are determined by structural parameters on different dimensional scales. In this paper, a two‐scale modelling method is proposed for a cellulose separator. At micro‐scale, a single fiber structural model was established with a cross‐sectional profile extracted through image processing, combined with the fiber helix angle. At meso‐scale, a representative volumetric element model and a two‐dimensional random fibrous model for the fibrous network of the cellulose separator were developed. The elastic modulus in the machining direction (MD) and transverse direction (TD) of the two models were calculated by finite element simulation and compared with experimental data. The results show that the elastic modulus of the models is slightly larger than that from experiments. Compared to experiments, the relative errors in the MD and TD of the representative volumetric element model are 2.80% and 6.78%, respectively. The relative errors in the MD and TD of the two‐dimensional random fibrous model are 6.70% and 8.47%, respectively. Consequently, multi‐scale modelling is proven to have considerable value in investigating the properties of fibrous materials. © 2019 Society of Chemical Industry     

Effect on Mechanical Performance of UHMWPE/HDPE-Blend Reinforced with Kenaf,Basalt and Hybrid Kenaf/Basalt Fiber

The aim of this study was to investigate the performance of UHMWPE/HDPE-reinforced kenaf, basalt and hybrid kenaf/basalt composites. Mechanical testing of these samples was carried out such as tensile, flexural (three-point bending) and an impact test (Charpy). Pure resin (UHMWPE/HDPE) samples were tested and compare with reinforced 10% weight fraction of kenaf, basalt and hybrid kenaf/basalt samples to identifying their contribution and potential in this new composite material. UHMWPE/ HDPE sample was produced in constant ratio 60:40 respectively via extrusion process. Basalt reinforced UHMWPE/HDPE generates the highest elastic modulus result compared to kenaf and hybrid kenaf/basalt as a reinforcement material. The tensile results of kenaf reinforcement UHMWPE/HDPE samples are significantly higher (20%) than pure blend resin, which is an indication for good performance of kenaf, basalt and hybrid kenaf/basalt to be used in UHMWPE/HDPE-blend polymers. The flexural and Charpy strengths show the drawback results, where performance of polymer is reduced 5% with the absence of kenaf. It can be concluded that kenaf, basalt and hybrid kenaf/basalt fiber successfully increase the UHMWPE/HDPE blends performance especially under tensile loading.