Abstract Three-dimensional (3D) six-directional braided carbon/epoxy composites are widely used in aerospace field and this is successfully fabricated in this study. The composite is thoroughly analyzed with regard to both mechanical properties and failure mechanism in connection with the affecting factors, i.e., loading direction and temperature. At room and elevated temperatures, the in-plane compressive properties of such composites are obtained, and their failure mechanism is evaluated. A progressive damage model is established to predict the mechanical properties and to quantitatively interpret the failure behavior. At room temperature, longitudinal curve increases linearly and then drops suddenly, indicating brittle characteristics; the transverse curve is linear up to the failure point and drops gradually after the peak point. At elevated temperatures, the curves become non-linear up and the mechanical properties of composites decrease. At room temperature, the longitudinal compression presents shear fracture and shear plane exfoliation. Meanwhile, failure is observed in fiber rupture in various directions and matrix cracks. The transverse failure is observed in shear cracks and braiding fibers shedding. At elevated temperatures, 45° shear cracks are developed, the fibers are pulled out, the texture of matrix softens and exfoliates, and a noticeable debonding of the interface occurs.

中文翻译：

---

大编织角3D六向编织复合材料面内压缩性能及破坏的实验与数值研究

摘要 三维（3D）六向编织碳/环氧树脂复合材料广泛应用于航空航天领域，并在本研究中成功制备。结合影响因素，即加载方向和温度，对复合材料的机械性能和失效机制进行了彻底的分析。在室温和高温下，获得了这种复合材料的面内压缩性能，并评估了它们的失效机制。建立渐进式损伤模型以预测机械性能并定量解释失效行为。常温下纵向曲线呈线性上升后突然下降，为脆性特性；横向曲线在故障点之前是线性的，在峰值点之后逐渐下降。在升高的温度下，曲线变得非线性并且复合材料的机械性能下降。在室温下，纵向压缩呈现剪切断裂和剪切平面剥落。同时，在不同方向的纤维断裂和基体裂纹中观察到失效。在剪切裂纹和编织纤维脱落中观察到横向破坏。在升高的温度下，会产生 45° 剪切裂纹，纤维被拉出，基质的质地软化和剥落，界面出现明显的脱粘。在剪切裂纹和编织纤维脱落中观察到横向破坏。在升高的温度下，会产生 45° 剪切裂纹，纤维被拉出，基质的质地软化和剥落，界面出现明显的脱粘。在剪切裂纹和编织纤维脱落中观察到横向破坏。在升高的温度下，会产生 45° 剪切裂纹，纤维被拉出，基质的质地软化和剥落，界面出现明显的脱粘。