基于显微CT图像的近场动力学建模与复合材料微结构破坏模拟

随着纤维增强复合材料应用领域的不断扩展且用量激增，亟需理清复合材料微观结构损伤对宏观力学性能影响的内在机制。因此，发展针对纤维增强复合材料微结构破坏过程的建模与高效模拟方法就显得十分重要。本文借助显微CT(Micro-computed Tomography)扫描技术，提出了一种基于显微CT图像中像素点离散的近场动力学建模与模拟方法。一方面，近场动力学作为一种由积分方程建模的非局部理论，便于采用基于空间点离散的数值计算方法，相比传统的连续介质力学能够更有效地模拟材料从连续变形到裂纹萌生与扩展(非连续变形)的全过程。另一方面，对显微CT图像使用像素点灰度阈值分割处理技术，能够快速建立含有复合材料原位微结构信息的空间点离散模型。该离散模型可以直接用于微结构破坏过程的近场动力学模拟，从而避免了传统的数值模拟技术需要依据像素点先建立光滑的几何模型、再划分成有限单元网格的复杂前处理过程，并且极大地保留了复合材料的原位组分分布信息。数值模拟结果表明，基于显微CT图像的近场动力学建模方法能够精确捕捉到复合材料微结构信息，并能准确模拟纤维增强复合材料的微结构破坏过程。

Peridynamic modeling through micro-CT images for failure simulation of composite microstructure

Since the fields of fiber-reinforced composites expand continuously, the effect of microstructure damage on the mechanical properties of composites has become an essential yet unclarified issue. Therefore, it is necessary to develop a feasible and efficient method to model and simulate the microstructure failure of fiber-reinforced composites. In this paper, a peridynamic-based computational scheme is proposed to simulate the failure of composite microstructure, using discrete pixel points of micro-computed tomography (micro-CT) images taken from the micro-CT scanning technology. Peridynamics is a nonlocal theory based on integral equations. Therefore, it is more convenient to implement particle-based numerical methods, which makes it more effective to simulate the failure process from deformation to fracture. By introducing the gray threshold segmentation technology into the micro-CT image processing, a particle discretization containing in situ information of composite materials can be obtained, which is employed for peridynamic simulations. Consequently, the complex geometric reconstruction and finite element partition are unnecessary, whereas the in situ information of composite microstructure, such as fiber, matrix, and voids, is preserved as possible. The simulation results show that the peridynamic modeling based on micro-CT images can accurately capture the microstructure information of composites and successfully simulate the failure evolution of composite materials.