Parametric Characteristics Analysis of Three-Unit-Cell Model in 3D Seven-Directional Braided Composites

Three-dimensional (3D) braided composites are widely used in aerospace and automotive industries due to their superior mechanical properties. However, traditional 3D four-directional or five-directional braided composites exhibit limitations in multi-axial load-bearing capacity and structural stability under complex stress conditions. To address these challenges, we propose a novel 3D seven-directional braided composite structure, which enhances mechanical performance in both axial and transverse directions by incorporating additional reinforcement yarns. This structure consists of braiding yarns, axial yarns, six-directional yarns and seven-directional yarns, forming a more uniform and stable interlacing network. Based on the positional relationships between yarns, a parametric three-unit-cell model (incorporating interior, surface, and corner unit-cells) was developed to analyze the effects of braiding parameters and angles on fiber volume fraction and unit-cell geometry. Especially, an automated modeling plugin was created to efficiently generate unit-cell models for further mechanical analysis. The proposed 3D seven-directional braided composite provides a new theoretical framework for designing advanced textile composites, expanding their potential for diverse engineering applications.