A coupled MD-FE simulation method accounting for interphases in nanoparticle filled thermoplastics.

该建议旨在扩展最近开发的混合MD-FE模拟方案，将其应用于以聚合物-固体界面为主的材料。只有基于颗粒的方法才能从本质上解决界面相的微观结构和力学行为。因此，我们继续进行以下设置：一个粗粒度的MD域，其中包含一个单一的纳米粒子和尽可能多的聚合物，以确保在边界处的散装行为，包括到FE域。有限元边界用于施加各种类型的变形，并记录颗粒、周围界面和体积的整体应力响应。有了这些数据，一个纯粹的连续对应的混合设置的参数迭代调整，直到它的行为相同。作为其主要特征，连续ersatz模型取代粒子和聚合物之间的界面由吉布斯意义上的表面能控制的界面。这可以被理解为3-D界面内的微观尺度性质分布到2-D连续体力学模型中的浓缩。最终，在对连续ersatz模型进行建模之后，将实现宏观结构模拟，从而适当考虑纳米颗粒周围发生的界面效应。

This proposal aims at an extension of a recently developed, hybrid MD-FE simulation scheme towards its application to materials dominated by polymer-solid interphases. Only particle-based methods are able to intrinsically resolve microstructure and mechanical behavior of interphases. Therefore, we proceed with the following setup: A coarse-grained MD domain, which contains a single nanoparticle and as much polymer as necessary to ensure bulk behavior at the boundary, is included into a FE do-main. The FE boundary is used to apply various types of deformations and to record the overall stress responses of particle, surrounding interphase and bulk. With these data, the parameters of a purely continuous counterpart to the hybrid setup are iteratively adjusted until it behaves identically. As its main feature, the continuous ersatz-model substitutes the interphase between particle and polymer by an interface governed by a surface energy in the sense of Gibbs. This can be understood as a condensation of micro-scale property profiles within the 3-D interphase into a 2-D continuum mechanical model. Ultimately, after homogenizing the continuous ersatzmodel, macroscopic structure simulations allowing for a due consideration of interphase effects as occurring around nanoparticles are to be realized.