含非均匀界面相粒子填充复合材料的有效比热

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. 

EFFECTIVE SPECIFIC HEATS OF SPHERICAL PARTICULATE COMPOSITES WITH INHOMOGENEOUS INTERPHASES

The effective thermoelastic properties of spherical particulate composites with inhomogeneous interphases are studied. Particular emphasis is put on discussing the influence of the radial distribution of the interphase properties on the effective specific heats. Firstly, the inhomogeneous interphase is modeled by multiple concentric layers and the material properties are assumed to be homogeneous in each layer. The composite-sphere model, in which an interphase layer is embedded between the matrix and inclusion, is applied to derive the effective bulk modulus, thermal expansion coefficient (CTE) and specific heats. Secondly, for the case that the interphase properties vary continuously along the radial direction, a set of differential equations are established to determine the effective themoelastic properties of the composites. When the distribution of the Young's modulus of the interphase follows a power law, the analytical expressions of the effective properties are obtained by solving the differential equations. The effective CTE predicted by the present model is in good agreement with the experimental data. It is found that the distribution of both the interphase elastic moduli and the interphase CTE have great effects on the effective specific heats; however, only the distribution of the interphase CTE has significant impacts on the effective CTE.