A three dimensional multiscale method for modeling fracture in nanocomposites

本研究方案的主要目的是开发和验证用于纳米复合材料断裂分析的三维多尺度方法。纳米复合材料由聚合物基质和粘土增强材料组成，有望显著改善纯聚合物的机械和热性能。该方法通过层次化的升阶方法将纳米尺度过渡到微观尺度，通过并发的多尺度方法将微观尺度过渡到宏观尺度，即单位分割丰富的Arlequin方法。我们将使用扩展的有限元方法在微观和宏观尺度上模拟断裂，而将使用分子动力学(MD)模拟来确定微观模型的材料参数。由于纳米复合材料的断裂过程区较大，粘聚区模型将在微观尺度上得到应用。据我们所知，用三维多尺度方法研究聚合物基材料的断裂问题是为数不多的尝试之一。该方法将通过与前期工作中已获得的实验数据进行比较来验证。最终目标是更好地了解纳米复合材料的断裂，以便改进本构模型并支持这些材料的未来设计(计算材料设计)。

The main objective of this research proposal is to develop and validate a three-dimensional multiscale method for the analysis of fracture in nanocomposite materials. Nanocomposites consist of a polymer matrix and a clay reinforcement that promises to significantly improve the mechanical and thermal properties of pure polymers. The method will brigde three scales: the nano-scale to the micro-scale through a hierarchical upscaling approach and the microscale to the macro-scale by a concurrent multiscale method; i.e. a partition of unity enriched Arlequin method. We will use the extended finite element method to model fracture on the micro-scale and the macro-scale while molecular dynamics (MD) simulations will be used in order to determine the material parameters for the microscopic models. Cohesive zone models (CZM) will be used on the micro-scale as the fracture process zone in nanocomposites is large. To our best knowledge, it is one of the few attempts for a three-dimensional multiscale method that is used to 1. bridge three scales and 2. is applied to study the fracture of polymer-based materials. The method will be validated by comparisons to experimental data already obtained in the preliminary work. The final goal is to better understand the fracture of nanocomposites in order to improve constitutive models and to support future design of those materials (Computational Materials Design).