短纤维增强金属基复合材料拉伸变形的屈服行为的理论研究

运用空间轴对称弹塑性有限元方法的混合律模型,推导出应力应变分配系数的解析表达式。并由此提出了一种新的定义复合材料比例极限和屈服强度的方法,进而研究了材料参数（纤维长径比、纤维体积分数、纤维根间距和基体应变硬化指数）对短纤维金属基复合材料拉伸变形行为的影响。     

颗粒团聚对Al基SiC颗粒增强复合材料的流变形为影响

基于微观组织的有限元分析模型,研究颗粒团聚对Al基SiC颗粒增强金属基复合材料流变行为的影响。通过建立的3种增强颗粒分布的胞元模型（一个团聚现象、两个团聚现象和随机分布）,分析讨论基体和增强颗粒中的等效应力和等效应变的分布规律,以此为基础,获得3种颗粒分布模型下的SiC颗粒增强Al基复合材料的应力应变曲线。结果表明：颗粒增强金属基复合材料的流变行为和力学响应与增强颗粒的分布非常敏感,但在弹性变形阶段这种影响就相对较弱。从增强颗粒的最大主应力分布来看,颗粒团聚增加了SiC颗粒开裂的概率。从基体的静水应力分布来看,颗粒团聚将促进早期的界面脱粘和在韧性基体中形成微空洞。     

颗粒增强镁基复合材料热残余应力及其对宏观力学性能的影响

采用有限元方法对Si CP/AZ91复合材料制备后的热残余应力进行了数值模拟,建立了平面应力多颗粒随机分布的几何模型,研究了颗粒形状对该复合材料热残余应力的影响。通过简化模型,研究了受静态外力载荷时复合材料内部的热残余应力场变化。同时利用Taylor非局部应变梯度塑性理论和有限元法相结合,研究了热残余应力、颗粒形状及颗粒尺寸效应对颗粒增强金属基复合材料拉伸变形行为的影响。同时还说明了热残余应力对基体塑性变形的影响过程。     

铸造混杂增强金属基复合材料研究进展

对混杂增强金属基复合材料的铸造方法，常见的4种增强体混杂类型，连续纤维／颗粒（晶须），短纤维（晶须）／短纤维，短纤维（晶须）／颗粒，颗粒／颗粒混杂增强金属基复合材料的基础研究现状进行了综述，分析和讨论，指出开发预制体制备方法，制备出增强体混杂均匀的参制体，以及研究增强体的行为交互作用和机理是混杂增强金属基复合材料领域的进一步研究方向。     

短纤维增强金属基复合材料微屈服行为的细观力学分析

在Eshelby等效夹杂方法和双夹杂模型等的基础上建立了细观力学模型，定量计算了短纤维增强金属基复合材料的微屈服行为．计算结果表明：在基体材料的微屈服行为符合Brown—Lukens线性规律的情况下，复合材料的α-(ε^ρ)^1^/^2也近似符合Brown-Lukens规律．同时，计算了增强体短纤维的含量、形状、热残余应力和位错密度诸因素对复合材料微屈服规律的影响．     

改善颗粒增强金属基复合材料塑性和韧性的途径与机制

评述了影响颗粒增强金属基复合材料塑性和韧性的各种因素,在此基础上深入研究了颗粒形状对ＳｉＣｐ／ＬＤ２复合材料塑性和断裂韧性的影响规律。采用有限单元法分析不同形状的ＳｉＣ颗粒增强的ＬＤ２复合材料的微区力学环境和整体力学行为,结果表明颗粒的尖锐化导致基体内应变集中和颗粒尖端断裂的可能性加剧,因而降低材料的塑性;而在外加载荷的作用下,由于复合材料基体整体均处于较高的加工硬化状态,因此颗粒形状对材料断裂韧     

SiC_(foam)/Al双连续相复合材料的压缩行为

采用实验和模拟相结合的方法,利用ANSYS有限元软件对SiCfoam/Al(碳化硅泡沫增强铝基复合材料)双连续相复合材料的压缩行为进行了研究,分析变形过程中应力应变分布和材料特殊双连续结构对复合材料性能的影响。结果表明:应力和应变分布都具有明显的轮廓曲线,且与SiC泡沫轮廓吻合,最大应力和应变均出现在泡沫筋的连接区,加速了材料的失效。复合材料的弹性模量同时具有奇异的成分效应和结构效应,即弹性模量不但与材料成分有关,而且由材料中连续的强化相决定,特殊的双连续相结构使复合材料具有高的弹性模量和压缩屈服强度。随着增强体体积分数的增加,复合材料的屈服强度具有最大值,模拟结果和实验结果一致。     

短纤维／晶须增强金属基复合材料的弹塑性本构关系

研究了短纤维／晶须增强金属基复合材料在弹塑性变形中的应变分布，得到了增强体与基体应变的统计规律、提出了短纤维／晶须增强金属基复合材料的材料模型、导出了相应的弹塑性本构关系，预测了硼酸铝晶须增强Al基([AlBO]w／Al)复合材料单轴拉伸应力应变关系．结果与实验吻合良好。     

空心微珠增强铝基复合材料细观力学性能的数值模拟

基于代表性体积元的细观力学有限元的方法预测了空心微珠增强铝基复合材料的有效弹性模量、弹塑性应力应变和空心微珠与基体的界面性能.研究表明:影响复合材料有效弹性模量的重要参数为:空心微珠体积百分比(V4)和空心微珠壁厚与空心微珠半径的比值(t/R).同时也发现复合材料的颗粒增强金属基材料的特性随着空心微珠Vf的增加而减弱.     

SiC对SiC/6066铝基复合材料挤压过程力学行为的影响

利用有限元方法分析了SiC颗粒在不同形状、体积分数时对Al基复合材料挤压过程力学行为的影响,并对试样进行了拉伸试验。结果表明,随着SiC颗粒角度减小,颗粒的应力很快增大,基体的应变呈增大趋势;随SiC颗粒体积分数的增大,颗粒的应力、基体的应变以及该复合材料的弹性模量及屈服强度呈增大的趋势。     

Effect of thermal residual stresses on yielding behavior under tensile or compressive loading of short fiber reinforced metal matrix composite

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短纤维增强金属基复合材料拉伸应力场的有限元数值分析

运用空间轴对称弹塑性有限元方法,研究了短纤维增强金属基复合材料拉伸应力场分布。研究表明,基体和纤维的应力分布及基体塑性行为具有明显的不均匀性,材料参数（纤维长径比,纤维体积分数,纤维根间距和基体应变硬化指数）以不同方式通过影响应力传递基体约束变形和基体应变硬化进而影响应力场分布。     

An FEM investigation into the behavior of metal matrix composites: Tool–particle interaction during orthogonal cutting

An analytical or experimental method is often unable to explore the behavior of a metal matrix composite (MMC) during machining due to the complex deformation and interactions among particles, tool and matrix. This paper investigates the matrix deformation and tool–particle interactions during machining using the finite element method. Based on the geometrical orientations, the interaction between tool and particle reinforcements was categorized into three scenarios: particles along, above and below the cutting path. The development of stress and strain fields in the MMC was analyzed and physical phenomena such as tool wear, particle debonding, displacements and inhomogeneous deformation of matrix material were explored. It was found that tool–particle interaction and stress/strain distributions in the particles/matrix are responsible for particle debonding, surface damage and tool wear during machining of MMC.     

几何特征对SiC颗粒增强Al基复合材料力学行为的影响

利用有限元方法建立三维模型分析SiC颗粒在不同形状、不同体积分数和不同尺寸时对Al基复合材料力学行为的影响,并进行拉伸试验研究.结果表明,颗粒形状比颗粒尺寸和颗粒体积分数对材料的应力、应变分布及材料韧性的影响大.颗粒尖角附近有严重的应力集中现象,在外力方向上颗粒端部附近的基体上的应变也有集中现象.随颗粒角度的减小,颗粒的应力很快增大而韧性减小,材料的弹性模量有增大的趋势.随颗粒体积分数的增大,颗粒的应力有减小趋势,材料的弹性模量呈增大趋势.颗粒尺寸较小时(平均尺寸为5 μm),颗粒尺寸对材料的应力及应变的影响小.     

Finite Element Analysis of the Microstructure–Strength Relationships of Metal Matrix Composites

The influence of the shape and spatial distribution of reinforced particles on strength and damage of metal matrix composite （MMC） is investigated through finite element method under uniaxial tensile, simple shear, biaxial tensile, as well as combined tensile/shear loadings. The particle shapes change randomly from circular to regular n-sided polygon （3 ≤ n ≤ 10）; the particle alignments are determined through a sequentially random number stream and the particle locations are defined through the random sequential adsorption algorithm. The ductile failure in metal matrix and brittle failure in particles are described through damage models based on the stress triaxial indicator and maximum principal stress criterion, respectively, while the debonding behavior of interface between particles and matrix is simulated through cohesive elements. The simulation results show that, under different loadings, interface debonding is the dominated failure mechanism in MMCs and plastic deformation and ductile failure of matrix also play very important roles on the failure of MMCs.     

Effect of particle characteristics on deformation of particle reinforced metal matrix composites

The particle characteristics of 15% SiC particles reinforced metal matrix composites (MMC) made by powder metallurgy route were studied by using a statistical method. In the analysis, the approach for estimation of the characteristics of particles was presented. The study was carried out by using the mathematic software MATLAB to calculate the area and perimeter of each particle, in which the image processing technique was employed. Based on the calculations, the sizes and shape factors of each particle were investigated respectively. Additionally, the finite element model (FEM) was established on the basis of the actual microstructure. The contour plots of von Mises effective stress and strain in matrix and particles were presented in calculations for considering the influence of microstructure on the deformation behavior of MMC. Moreover, the contour maps of the maximum stress of particles and the maximum plastic strain of matrix in the vicinity of particles were introduced respectively.     

颗粒增强金属基复合材料的研究现状及展望

从材料的选择、制备技术和性能等方面对颗粒增强金属基复合材料的研究现状进行综合评述。分析了颗粒增强金属基复合材料发展过程中存在的一些问题及改进措施 ,指出了颗粒增强金属基复合材料的几个重要发展方向 :制备技术的改进、应用范围向特色应用领域的拓宽和再生回收的重视     

Simplified prediction model for elastic modulus of particulate reinforced metal matrix composites

Some structural parameters of the metal matrix composite, including particulate shape and distribution do not influence the elastic modulus. A prediction model for the elastic modulus of particulate reinforced metal matrix Al composite was developed and improved. Expressions of rigidity and flexibility of the rule of mixing were proposed. A five-zone model for elasticity performance calculation of the composite was proposed. The five-zone model is thought to be able to reflect the effects of the MMC interface on elastic modulus of the composite. The model overcomes limitations of the currently-understood rigidity and flexibility of the rule of mixing. The original idea of a five-zone model is to propose particulate/interface interactive zone and matrix/interface interactive zone. By integrating organically with the law of mixing, the new model is found to be capable of predicting the engineering elastic constants of the MMC composite.