Electro-fracture Studies of Natural Fiber Composites

ABSTRACT

The electro-fracture studies on jute/epoxy composites are conducted for monitoring damage under mode-I interlaminar fracture loading condition. A well-connected electrical network is built inside the composites by electro-flocking microcarbon fibers between the laminates and dispersing carbon nanotubes in the matrix. The effect of carbon fiber length and density on the electro-fracture behavior is studied. The change in electrical resistance is measured using a novel four-probe method through the thickness direction of cantilever beam test specimen. Results show that the maximum increase of fracture initiation toughness is 75% by the composite with carbon fibers length of 350 μm and fiber density of 2000 fibers/mm² compare to composites with no carbon fibers. For all composite types, the increase in resistance is not noticeable before crack initiation. The cycles of fracture energy build up and release during the crack propagation are accurately detected onsite by the composite with carbon fiber length of 350 μm and fiber density of 2000 fibers/mm².

摘要

对黄麻/环氧树脂复合材料在型层间断裂载荷作用下的电损伤进行了研究. 通过在复合材料层合板之间电植绒微碳纤维和在基体中分散碳纳米管，在复合材料内部形成了一个连接良好的电网络. 研究了碳纤维长度和密度对电致断裂行为的影响. 采用一种新的四探针法，通过悬臂梁试件的厚度方向来测量电阻的变化. 结果表明，碳纤维长度为350μm、纤维密度为2000纤维/MM2的复合材料与无碳纤维复合材料相比，断裂韧性最大提高75%. 对于所有类型的复合材料，在裂纹萌生之前，电阻的增加并不明显. 采用碳纤维长度为350μm、纤维密度为2000纤维/mm~2的复合材料，对裂纹扩展过程中的断裂能积累和释放循环进行了现场精确检测.

KEYWORDS:

• Structural health monitoring
• natural fiber composites
• electro-fracture response
• mode-I interlaminar fracture
• R-curves

关键词:

• 结构健康监测
• 天然纤维复合材料
• 电断裂响应
• -型层间骨折
• R-曲线

Acknowledgments

The authors acknowledge the financial support of the National Science Foundation (NSF) of United States of America, under grant numbers CMMI-1563040 and NSF-MRI-1726239.

Additional information

Funding

This work was supported by the Division of Civil, Mechanical and Manufacturing Innovation [CMMI-1563040].