熔接线是聚合物材料成型加工中常见缺陷之一，而熔接线区域的分子链取向和缠结程度是影响其力学性能的关键因素。本项目从微观结构对熔接线区域的力学性能进行分析，探索微观分子信息对熔接线区域力学性能的影响以及加工工艺参数对其的影响规律。具体内容包括：在多尺度建模方面，以宏观连续介质力学和微观分子动力学模型为基础，考虑跨尺度信息双向传递的影响，建立耦合的宏-微观多尺度模型；在多尺度计算框架下，基于人工神经网络优化和区域分解技术，提出高效稳定的多尺度耦合算法；根据数值模拟结果和物理分析，研究熔接线区域的力学性能并探索加工工艺对力学性能的影响规律。其中，建模方面的关键问题是跨尺度信息准确高效地传递方式的确定；计算方面的关键问题是宏微观区域的精准划分。通过本项目的研究，将为熔接线区域力学性能分析提供一套理论分析模型和数值计算方法，进而为聚合物成型过程中改善制品的力学性能提供一定的理论依据。

The weld line is the one of the typical molding defects in injection molding, the macromolecule orientation and intertwist degree of weld line region are all key factors influencing its mechanical properties. This project aims to investigate the mechanical properties and some influence rules of processing parameters on mechanical properties from microscopic point of view by numerical simulation. First, a coupling multi-scale model will be established based on continuum mechanics model and molecular dynamics model by considering the multi-scale transfer of information. Then a stable and efficient numerical method for the coupling model will be proposed by using the optimization of artificial neural network and a domain decomposition technique under the framework of multi-scale computation. Finally, based on numerical results and physical analysis, the mechanical properties of weld line region will be analyzed and some influence rules of processing parameters on mechanical properties will be revealed. The key problems of this project are the determination of the multi-scale information transfer method in the modeling stage, and the domain decomposition in the simulation stage. According to the study of this project, some of the key theories and technologies for simulating mechanical properties of weld line region from microscopic point of view will be settled, and it will provide an important theoretical basis for improving the mechanical properties of injection products.