The interface energy theory developed by Huang et al. is further extended to incorporate the effect of the residual interface stresses on the effective specific heats of multiphase thermoelastic nanocomposites. First, a micromechanics-based method is employed to derive the expressions of the effective specific heats at constant-strain and constant-stress of the composites. Second, in order to take into account the influence of the interface stresses on the overall properties of the nanocomposites, a thermoelastic interface constitutive relation expressed in terms of the first Piola-Kirchhoff interface stresses and the Lagrangian description of the generalized Young-Laplace equations are presented. Finally, by means of the Helmholtz free energy of the "equivalent inclusion" (the inclusion together with its interface), analytical expressions of the size-dependent effective specific heats of the nanocomposites are obtained. The model is illustrated by an example of a "three-phase thermoelastic composite" showing that the overall properties of the nanocomposites are influenced by the "residual interface stresses," which was sometimes ignored in the literature.

基于细观力学复合球模型研究了含非均匀界面相球形颗粒填充复合材料的有效比热和其他热弹性性质,讨论了界面相性质沿径向的分布对有效性质的影响。首先,将不均匀界面相沿径向离散为多个同心球壳,假设每个球壳内材料性质是均匀的,不同球壳内的材料性质沿径向满足一定的分布。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比热及有效体积模量、有效热膨胀系数的数值求解表达式。预测的有效热膨胀系数与实验结果吻合良好。另外,结果表明,界面相弹性模量和热膨胀系数的径向分布均对有效比热有较大的影响;而有效热膨胀系数虽然与界面相的模量和热膨胀系数都有关,但只有界面相热膨胀系数的径向分布对其影响较大。

提出了一种新的细观模型用以反映含连通开孔的饱和孔隙介质的结构特性。将流体作为基体,以取向随机分布的长柱形固体作为等效夹杂,利用Mori-Tanaka方法求解了饱和孔隙介质在排水和不排水状态时的有效弹性模量。该模型预测枫丹白露砂岩等岩土类饱和孔隙介质的有效弹性性质与实验相符很好。

本文用边界元方法求解颗粒填充复合材料的变形和界面分离问题,采用多子域法实现颗粒和基体之间的界面连续和分离条件,并采用主从自由度法(Master-Slave Elimination)[1]求解了界面从完美结合到分离的过程。算例表明,边界元法在此类问题中具有精度高和容易实施的优势。

The interface energy theory developed by Huang et al. is further extended to incorporate the effect of the residual interface stresses on the effective specific heats of multiphase thermoelastic nanocomposites. First, a micromechanics-based method is employed to derive the expressions of the effective specific heats at constant-strain and constant-stress of the composites. Second, in order to take into account the influence of the interface stresses on the overall properties of the nanocomposites, a thermoelastic interface constitutive relation expressed in terms of the first Piola-Kirchhoff interface stresses and the Lagrangian description of the generalized Young-Laplace equations are presented. Finally, by means of the Helmholtz free energy of the "equivalent inclusion" (the inclusion together with its interface), analytical expressions of the size-dependent effective specific heats of the nanocomposites are obtained. The model is illustrated by an example of a "three-phase thermoelastic composite" showing that the overall properties of the nanocomposites are influenced by the "residual interface stresses," which was sometimes ignored in the literature.