Micro-scale modeling of 3D needled nonwoven fiber preforms

This paper proposes a numerical modeling method for generating the virtual fiber structures of 3D needled nonwoven preforms. Microstructures of the preforms are investigated using Micro-CT technology. Geometric parameters of the fibers, including length, orientation and aggregation are statistically analyzed. Then the virtual fibers are generated based on the statistical parameters. Each virtual fiber is a flexible chain connected by truss elements with very short length. After that the virtual fibers are assembled together and compressed to a certain thickness. Deformations and contacts of the virtual fibers are simulated by finite element method using an explicit dynamics algorithm. Finally, 3D needled nonwoven preforms are modeled by numerical simulation of the needling process. The virtual fiber structures and the Micro-CT images are found to be in excellent agreement with each other. The modeling method of this study would be helpful for understanding internal fiber structures of 3D needled nonwoven preforms and provides a good basis to analyze the permeability for resin flow and mechanical properties of the composites.