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复合材料的宏观性能与参数设计 总被引:5,自引:0,他引:5
本文综述了预测复合材料宏观性能──有效刚度的几类方法:自洽模型、单胞模型以及它们的结合──自洽有限元法.阐述了复合材料发生弹塑性变形时的有关力学问题.基于细观力学的定量分析结果,探讨了面向材料宏观刚度的细观结构参数设计的基本原则,以期对建立复合材料细观结构设计的力学和数学模型有所启发. 相似文献
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将近片层-γTiAl基合金视为以等轴γ颗粒为基体,PST颗粒为夹杂的两相复合材料,基于细观力学自洽理论,对合金的有效弹性模量及基体和夹杂中的应力和应变场进行了解析分析计算,并结合细观力学的宏细观关联方法,确定了近片层-γTiAl基合金的宏观屈服的微观表征.结果表明:夹杂颗粒中的应力和应变场与外载及夹杂的体积分数f和椭球长细比ρ有关,软取向PST夹杂颗粒的微变形屈服导致近片层-γTiAl基合金材料的整体宏观屈服. 相似文献
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基于自洽法的电化学沉积修复饱和混凝土细观描述 总被引:2,自引:1,他引:1
针对当前电化学沉积修复混凝土缺乏细观层次上的理论描述,首先,以饱和混凝土的细观结构和电化学沉积修复的主要机理为基础, 提出了含电化学沉积产物、水和混凝土基体在内的三相复合材料细观力学模型. 其次,为了从细观层次定量描述电化学沉积修复对混凝土宏观性能的影响,基于自洽法对上述细观力学模型进行多层次均匀化处理,获取电化学沉积修复饱和混凝土的有效性能,其中,第一层均匀化是采用广义自洽模型获取等效夹杂的有效性能,第二层均匀化是采用自洽方法和沃伊特(Voigt) 上限相结合的方式获取修复混凝土的有效性能. 最后,为了验证该文所提出模型和方法的有效性,对比了该文的预测结果、试验数据和已有模型,结果表明了该文模型和方法是合理的. 相似文献
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基于细观力学复合球模型研究了含非均匀界面相粒子填充复合材料的有效热弹性性质,重点讨论了界面相性质的径向分布对有效比热的影响. 首先,将非均匀界面相沿径向离散为多个同心球壳,每个球壳内的材料性质假设是均匀的. 基于上述离散模型,利用含界面相的复合球模型,推导了复合材料的有效体积模量、有效热膨胀系数及有效比热的数值求解表达式;进一步,假设界面相的性质沿径向连续变化,建立了一组微分方程,上述有效性质依赖于该微分方程组的解. 特别地,当界面相杨氏模量为幂次分布时,通过求解该微分方程组得到了有效比热等热弹性性质的解析解. 算例结果表明,应用此方法预测的有效热膨胀系数与实验结果吻合良好;界面相热膨胀系数的径向分布对有效比热和有效热膨胀系数均有显著的影响,而界面相弹性模量的径向分布对有效比热有显著的影响,对有效热膨胀系数的影响相对较小. 相似文献
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基于细观力学复合球模型研究了含非均匀界面相粒子填充复合材料的有效热弹性性质,重点讨论了界面相性质的径向分布对有效比热的影响. 首先,将非均匀界面相沿径向离散为多个同心球壳,每个球壳内的材料性质假设是均匀的. 基于上述离散模型,利用含界面相的复合球模型,推导了复合材料的有效体积模量、有效热膨胀系数及有效比热的数值求解表达式;进一步,假设界面相的性质沿径向连续变化,建立了一组微分方程,上述有效性质依赖于该微分方程组的解. 特别地,当界面相杨氏模量为幂次分布时,通过求解该微分方程组得到了有效比热等热弹性性质的解析解. 算例结果表明,应用此方法预测的有效热膨胀系数与实验结果吻合良好;界面相热膨胀系数的径向分布对有效比热和有效热膨胀系数均有显著的影响,而界面相弹性模量的径向分布对有效比热有显著的影响,对有效热膨胀系数的影响相对较小. 相似文献
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混凝土材料宏观力学特性分析的细观单元等效化模型 总被引:5,自引:1,他引:4
提出了一种混凝土材料宏观力学特性分析的新方法—细观单元等效化模型。该方法从描述混凝土材料的细观尺度入手,采用Monte Carlo法生成由骨料颗粒及砂浆基质组成的混凝土试件的随机骨料模型;然后,依据混凝土材料特征单元尺度来剖分有限元网格并投影到建立的随机骨料模型上,各细观单元的有效力学特性则采用复合材料等效化方法来确定。本文方法体现了材料非线性宏观力学特性源于其内在的不均匀性这一认识,而对不均匀性的描述则是以网格剖分是否影响其宏观力学特性为准则。因此,本文方法较其他细观力学方法最大的优点在于极大地减小了体系自由度数目(特别是对于三维问题),从而提高了计算效率。算例分析初步验证了本文方法的高效性。 相似文献
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基于遗传算法的复合材料细观结构拓扑优化设计 总被引:2,自引:0,他引:2
利用高精度通用单胞模型将复合材料的细观拓扑结构与宏观力学性能结合起来,采用遗传算法对复合材料的细观结构进行优化,发展了基于遗传算法的复合材料细观结构拓扑优化设计方法.以材料的宏观力学性能为优化目标,从随机的初始细观结构出发,对复合材料纤维体积百分比进行约束,经过迭代获得满足设计要求的代表性体积单元.在优化过程中,对遗传算法的交叉过程作了较大的改进,实现了复合材料细观拓扑结构的任意变化,提高了对可行域的搜索效率.分别以极限剪切模量和泊松比为优化目标,验证了所提出优化方法的正确性和有效性. 相似文献
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弹塑性复合材料力学性能的细观研究 总被引:4,自引:0,他引:4
应用细观力学的Eshelby等效夹杂理论研究了复合材料的弹塑性问题。以铝基复合材料为例,建立了多轴载荷下复合材料弹塑性应力-应变关系,并且理论预报与实验结果符合较好,分析了夹杂形状、体积分数及加载路径对材料宏观性能的影响。同时,还研究了热塑性复合材料热膨胀系数与工艺温度之间的变化规律,分析了热残余应变对材料设计的影响。 相似文献
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Thermoelastic behavior of functionally graded particulate materials is investigated with a micromechanical approach. Based on a special representative volume element constructed to represent the graded microstructure of a macroscopic material point, the relation between the averaged strains of the particle and matrix phases is derived with pair-wise particle interactions, and a set of governing equations for the thermoelastic behavior of functionally graded materials is presented. The effective coefficient of thermal expansion at a material point is solved through the overall averaged strain of two phases induced by temperature change under the stress-free condition, and is shown to exhibit a weak anisotropy due to the particle interactions within the graded microstructure. When the material gradient is eliminated, the proposed model predicts the effective coefficient of thermal expansion for uniform composites as expected. If the particle interactions are disregarded, the proposed model recovers the Kerner model. The proposed semi-analytical scheme is consistent and general, and can handle any thermal loading variation. As examples, the thermal stress distributions of graded thermal barrier coatings are solved for two types of thermal loading: uniform temperature change and steady-state heat conduction in the gradation direction. 相似文献
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For the accurate prediction of the effective thermal conductivities of the twisted multi-filamentary superconducting strand, a two-step homogenization method is adopted. Based on the distribution of filaments, the superconducting strand can be decomposed into a set of concentric cylinder layers. Each layer is a two-phase composite composed of the twisted filaments and copper matrix. In the first step of homogenization, the representative volume element (RVE) based finite element (FE) homogenization method with the periodic boundary condition (PBC) is adopted to evaluate the effective thermal conductivities of each layer. In the second step of homogenization, the generalized self-consistent method is used to obtain the effective thermal conductivities of all the concentric cylinder layers. The accuracy of the developed model is validated by comparing with the local and full-field FE simulation. Finally, the effects of the twist pitch on the effective thermal conductivities of twisted multi-filamentary superconducting strand are studied. 相似文献
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S. V. Sheshenin B. P. Lazarev N. B. Artamonova 《Moscow University Mechanics Bulletin》2016,71(6):127-131
An approach is proposed to determine the effective relative expansion coefficient of a porous medium filled with water during its freezing. This approach is based on an asymptotic homogenization method. An explicit formula is derived to find the expansion coefficient in the case of open pores. In the case of closed pores, the expansion coefficient is a second-rank tensor. Its determination requires to solve the so-called local problems in a representative volume element. The proposed approach can be used to determine the effective expansion coefficient during the freezing of water in the soil. Its efficiency is confirmed for model and realistic geological structures. 相似文献
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《Comptes Rendus de l'Académie des Sciences》2000,328(12):855-862
The rheological behavior of setting heterogeneous materials is studied from a theoretical approach by means of the homogenization technique of periodic medium. These materials considered as suspensions of gas bubbles at finite concentration in a viscoelastic matrix with low compressibility, present the macroscopic behavior of a compressible viscoelastic medium. The shear and volume macroscopic moduli are of the same order of magnitude and directly proportional to that of the fluid. The effective compressibility of the gas (out of thermal equilibrium) is added to these fluid contributions. 相似文献
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SMA短纤维复合材料的热胀系数和相变应变系数 总被引:4,自引:0,他引:4
基于Eshelby的等效夹杂模型、Mori和Tanaka的场平均法,考虑到形状记忆合金(SMA)的强物理非线性,发展了增量型的等效夹杂模型(Incremental Equivalent Inclusion Model)。讨论了SMA短纤维增强的铝基复合材料的热胀系数和相变应变系数。特别研究了SMA短纤维复合材料纤维几何尺寸和体积分数等参数对SMA复合材料的热胀系数和相变应变系数的影响。这些工作对于指导材料设计和了解SMA复合材料热机械特性是非常有意义的。 相似文献
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计算微裂纹损伤材料有效模量的一种简单方法 总被引:7,自引:0,他引:7
给出了一种基于Taylor模型的有效介质方法。用以计算微裂纹相互作用对有效本构关系的影响,该方法假设每一个微裂纹位于一种有效介质之中,该有效介质的弹性模量由不考虑微裂纹相互作用的Taylor模型计算、和自洽方法相比,这种方法计算简单,而且结果更准确。 相似文献
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The present paper describes a micromechanics-based approach to the strength properties of composite materials with a Drucker–Prager matrix in the situation of non-associated plasticity. The concept of limit stress states for such materials is first extended to the context of homogenization. It is shown that the macroscopic limit stress states can theoretically be obtained from the solution to a sequence of viscoplastic problems stated on the representative elementary volume. The strategy of resolution implements a non-linear homogenization technique based on the modified secant method. This procedure is applied to the determination of the macroscopic strength properties and plastic flow rule of materials reinforced by rigid inclusions, as well as for porous media. The role of the matrix dilatancy coefficient is in particular discussed in both cases. Finally, finite element solutions are derived for a porous medium and compared to the micromechanical predictions. 相似文献
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In this work, a new homogenization method to estimate the effective behavior of viscoelastic heterogeneous materials with multi-coated reinforcements is presented. Unlike classical methods that are based on the Laplace transform, the present internal variables formulation operates directly in the time domain. Using the Green’s function techniques, the micromechanical approach is based on establishing a new integral equation adapted to scale transition methods. Using this integral equation, we apply a generalized self-consistent scheme to determine the local stress concentration equations and the effective behavior of multi-coated inclusion-reinforced materials. To assess the reliability of our model, some applications to the isotropic viscoelastic heterogeneous materials with homothetic spherical inclusions are given. The model is applied to the case of two-phase and three-phase materials, and the results are compared to exact solutions. Results for three-phase materials are presented regarding the influence of soft and stiff viscoelastic interphase on the effective behavior of heterogeneous materials. 相似文献