A detailed experimental study is performed for piezo resistance damage sensing on conductive glass fiber/epoxy composites under mode-I fracture conditions. The conductive composites are fabricated by homogeneously dispersing carbon nanotubes (CNTs) within the epoxy matrix and electro-flocking short carbon fibers onto the laminates along with a vacuum infusion process. A parametric study is done on the in-situ damage sensing properties by varying the carbon fiber lengths (150 µm and 350 µm) and the carbon fiber areal densities (500, 1000, 1500, and 2000 fibers/mm2). The change in resistance is captured with a four-point probe measuring methodology by measuring the resistance through the thickness of the composite. The crack initiation toughness value of the composites containing carbon fibers showed improvement over control composites. Composites containing 350 µm length carbon fibers and 2000 fiber/mm2 not only showed the best crack initiation toughness but also provided sensitive network for detecting crack growth.

中文翻译：

---

I型断裂载荷下多功能玻璃纤维复合材料的损伤传感

对 I 型断裂条件下导电玻璃纤维/环氧树脂复合材料的压电电阻损伤传感进行了详细的实验研究。导电复合材料是通过将碳纳米管 (CNT) 均匀分散在环氧树脂基体中并将短碳纤维电植绒到层压板以及真空灌注工艺来制造的。通过改变碳纤维长度（150 µm 和 350 µm）和碳纤维面密度（500、1000、1500 和 2000 纤维/mm2），对原位损伤传感特性进行了参数研究。通过测量复合材料厚度的电阻，使用四点探针测量方法捕获电阻的变化。含有碳纤维的复合材料的裂纹起始韧性值显示出优于对照复合材料的改进。