Factors governing the tensile strength of unidirectional carbon fiber reinforced plastic (CFRP) composites were experimentally investigated by focusing on the mechanical characteristics of the epoxy matrix. Correlation analysis was conducted to reveal the mechanical characteristics of the matrix that affect the surface stress concentration of an intact fiber caused by a fracture site in an adjacent fiber. The stress concentration factors (SCFs) were evaluated by implementing double-fiber fragmentation tests in conjunction with spring element model simulations. From investigating six types of epoxy materials, a reasonable correlation was observed between the matrix crack tip opening displacement (CTOD) and the SCF; the SCF increased approximately linearly with increasing CTOD. The results reported here suggest that CTOD is one of the important tensile-strength-controlling factors to consider for the development of stronger CFRP composites.

通过关注环氧基体的机械特性，通过实验研究了控制单向碳纤维增强塑料（CFRP）复合材料拉伸强度的因素。进行了相关分析，以揭示影响相邻纤维断裂部位所引起的完整纤维表面应力集中的基体机械特性。应力集中因子（SCF）通过结合弹簧元件模型仿真执行双纤维破碎测试进行评估。通过研究六种类型的环氧树脂材料，观察到基体裂纹尖端开口位移（CTOD）与SCF之间存在合理的相关性。SCF随着CTOD的增加而线性增加。