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为预测含孔隙复合材料单向层合板的有效弹性常数, 基于孔隙周边纤维分布和形态与三维Rankine椭圆体绕流流场的相似性, 提出了一种基于三维Rankine椭圆体绕流流场比拟的含孔隙复合材料弹性常数计算模型与方法。建立了含孔隙复合材料的有限元单胞计算模型, 用流场的速度变化比拟单胞内纤维体积分数的变化, 用流线形状比拟孔隙周边纤维的形态。通过对单胞施加周期性边界条件, 结合孔隙形态的概率分布模型和刚度平均法, 计算了含孔隙复合材料单向层合板的弹性常数。计算结果与实验数据有较好的一致性, 数值计算可以有效反映孔隙对复合材料单向层合板弹性常数的影响。 相似文献
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由于复合材料具体构造的复杂性,各种预测复合材料弹性常数的微观力学模型都难以确切模拟复合材料的几何构造、组份的物理状态及其真实的受力和变形情况。因而对既定模型的严格分析和数学推导不一定都能得到精确的预测。本文根据单向纤维复合材料中纤维分布的不均匀性,采用两级模型,简便地导得预测ET(E2)、GLT(G12)的理论表达式,收集不同复合材料的多组试验数据进行检验结果表明本文方法与其他八种预测公式相比,具有较高的精度。尤其是对GLT这个通常认为很难预测的剪切模量,本文方法似乎远优于其他公式。其中的机理还不能说得很清楚。 相似文献
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为了探究磨损对聚四氟乙烯(PTFE)和芳纶(Kevlar)纤维及酚醛树脂基体(PTFE-Kevlar/酚醛树脂)编织成的斜纹织物衬垫宏观弹性常数的影响。基于复合材料细观力学中的数学模型和体积平均算法,结合斜纹衬垫的细观结构,建立了不同磨损阶段的细观几何模型。从未磨损阶段入手,基于纤维织物几何参数及纤维各自弹性常数,利用MATLAB计算衬垫纤维束和基体的各自体积分数及相关矩阵,实现斜纹织物衬垫局部坐标系与整体坐标系下的弹性常数转化。构建了未磨损阶段衬垫的弹性常数计算模型,并利用算例证明方法的正确性,理论值与试验值的最大误差为5.88%。在此基础上,根据衬垫的结构,把磨损划分为6个阶段,建立不同磨损阶段的弹性常数计算模型。 相似文献
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为了求解缝合层合板中单层的弹性常数, 基于单层面内纤维走向与绕流流场中流线形状的相似性, 建立了与缝合单胞相对应的有限空间定常二维无粘性不可压理想流体的无旋绕流流场模型, 流场的几何边界与单胞的边界一致, 绕流物面与缝线截面形状一致。用该流场的速度变化描述单胞面内纤维体积含量的变化, 用流线形状描述缝线周围面内纤维的变形。以流场模型为基础, 用细观力学方法和均匀化方法求得缝合单层的弹性常数,结果与实验值吻合。最后用流场模型分析了缝合参数对缝合单层弹性常数的影响。 相似文献
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采用复合材料细观有限元分析方法,并借助先进循环塑性本构模型的有限元实现,对颗粒性态的随机性对SiC颗粒增强6061Al复合材料棘轮行为的影响进行了有限元数值模拟。采用随机序列吸附方法(RSA)生成各种多颗粒随机分布的模型,探讨了颗粒分布方式、数目、形状和大小以及各自的随机性对复合材料棘轮行为的影响。研究发现:颗粒尺寸越小、数目越多、分布在基体表面的比例越大,颗粒的增强效果越好;颗粒的大小和空间位置分布越均匀,复合材料抗循环变形的能力越强;球形颗粒和均匀分布的假设可以得到很好的模拟结果。 相似文献
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为了预测二维机织复合材料的弹性性能,建立了有限元力学分析模型。基于二维机织复合材料的几何特征,建立了参数化的单胞模型;考虑了织物纤维束呈现出的各向异性材料特征,将有限元中材料主方向转化到纤维屈曲方向,建立其力学分析有限元模型;分析了单胞边界面保持平面假设的不足,提出了对于二维机织复合材料通用的周期边界条件,获得了更为准确的二维机织复合材料的工程弹性常数。结果表明:织物衬垫单胞边界面,在单向拉伸载荷和纯剪切载荷下,呈凹凸翘曲变形,即为周期边界;应用给出的织物参数化几何建模方法与有限元求解方法,可以精确地获得工程弹性常数,数值计算结果与实验值吻合较好。 相似文献
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Preparation and some properties of SiC particle reinforced aluminium alloy composites 总被引:4,自引:0,他引:4
Aluminium alloy composites containing various particle sizes of 10 and 20 wt.% SiC particles were prepared by molten metal mixing and squeeze casting method under argon gas. The stirring was carried out with graphite impeller during addition of particle. The molten mixture was poured into a die when the stirring was completed and metal matrix composites were produced by applying the pressure. Optical microscopic examination, hardness, density and porosity measurement were carried out. Moreover, metal matrix composites were machined at various cutting speeds under a fixed depth of cut and feed rate using different cutting tools. It is observed that there was a reasonably uniform dispersion of particles in the matrix alloy. The density decreased with decreasing particle sizes, but porosity decreased considerably with increasing particle size. In addition, the tool life decreased considerably with increasing cutting speeds for all tests. Among cutting tools, the wear resistance of Al2O3 coated tools showed better performance than those of the other tools without chip breaker geometries in the machining of SiCp-reinforced composites. 相似文献
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采用微机控制电子万能实验机和分离式霍普金森压杆(SHPB)对石墨烯增强的铝基复合材料和碳化硅增强的铝基复合材料进行准静态压缩实验和动态冲击实验,研究石墨烯增强铝基复合材料在不同应变率下的冲击力学性能,采用SEM扫描电镜研究石墨烯增强的铝基复合材料和碳化硅增强的铝基复合材料的形貌特征。结果表明:在各个应变率载荷下,添加石墨烯和添加碳化硅都增强了铝合金的屈服强度,其中,添加石墨烯对铝合金的屈服强度提升更加明显,但不影响材料的应变硬化率;相较于在材料中添加碳化硅,添加石墨烯弱化了材料的应变率效应,在高应变率条件下,添加石墨烯降低了材料的强度极限;选取部分实验数据,拟合确定了添加石墨烯和添加碳化硅两种复合材料的J-C和Z-A本构方程的参数,并比较了两种本构模型的预测能力,对于本工作所研究的复合材料,J-C模型的预测能力更好。 相似文献
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Using a push-rod dilatometer, we measured between 76 and 390 K the thermal expansion of a particle-reinforced-composite wrought plate obtained by powdermetallurgy methods. The particles, 30% by volume, consisted of monocrystals of -SiC with sizes near 10 m. The matrix consisted of a 6061 aluminum alloy with original particle sizes near 20 m. We found the perpendicular thermal expansivity, 3, higher by 26% than the in-plane thermal expansivity, 1-2. These values differ from a rule-of-mixture prediction by –3 and –23%, respectively. All three i, components lie outside the Rosen-Hashin bounds. Levin's isotropic model agrees within 10% with the 1-2-3 average. Both the anisotropy and the bounds violation result from microstructural nonhomogeneity arising from processing. Rosen and Hashin's transverse-isotropicsymmetry relationships account approximately for these effects by introducing the anisotropic elastic constants. Using neutron diffraction, we determined that the SiC particles are textureless.Paper presented at the Tenth International Thermal Expansion Symposium, June 6–7, 1989, Boulder, Colorado, U.S.A. 相似文献
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Pulsed metall inert gas (MIG) welding and its effects on the microstructure and element distribution of an aluminum matrix reinforced with SiC composite material 下载免费PDF全文
A. Uluköy 《Materialwissenschaft und Werkstofftechnik》2017,48(2):163-176
This study aims to demonstrate the effects of pulsed current on the welding pool and fusion zone microstructures of the aluminum 2014 alloy matrix composite material reinforced with 14 and 20 vol% SiC particles. A programmable synergic controlled MIG welding machine with pulsed power supply was used. One hundred Ampere and 120 Ampere pulsed current values were used to determine the effect of heat input on microstructures. A 1 mm diameter SG‐AlSi5 wire was used as filler material. The microstructures were studied using a scanning electron microscope (SEM) with energy dispersive X‐ray (EDX) spectroscopy, and the phase analyses were performed via X‐ray diffraction analyzer (XRD). The study showed that increasing the SiC rate has a greater effect on the formation of Al4C3 phase than increasing the heat input values. Al4C3 formation was not formed as a needle‐like structure. 相似文献
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为提高颗粒增强金属基复合材料的力学性能,采用基于微观组织的胞元模型建模方法,并利用有限元软件ABAQUS着重分析了界面层厚度以及界面层强度对复合材料性能的影响,通过对复合材料中各组成部分的应力、应变云图的获取,形象地说明了各部分的变形规律.研究结果表明,在弱界面层下,随着界面层厚度的增加,复合材料的强化效果并不显著,而在强界面层下,随着界面层厚度的增加,强化效果非常明显;就界面层强度来说,界面越强,所表现出的强化效果就越明显,但当界面层强度比基体大得多时,随着界面层强度的增加,虽然复合材料的强化呈递增趋势,但是递增的幅度已逐渐降低. 相似文献
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