Nor Fethma M, Lim Joong Yeon, Tamin Mohd Nasir, Lee Ho Yong, Kurniawan D
Department of Mechanical Engineering, Curtin University, Miri 98009, Malaysia.
Department of Mechanical, Robotics, and Energy Engineering, Dongguk University, Seoul 04620, Korea.
Polymers (Basel). 2020 Apr 14;12(4):904. doi: 10.3390/polym12040904.
The mechanics of damage and fracture process in unidirectional carbon fiber reinforced polymer (CFRP) composites subjected to shear loading (Mode II) were examined using the experimental method of the three-point end-notch flexure (3ENF) test. The CFRP composite consists of [0] with an insert film in the middle plane for a starter defect. A 3ENF test sample with a span of 50 mm and interface delamination crack length of 12.5 mm was tested to yield the load vs. deformation response. A sudden load drop observed at maximum force value indicates the onset of delamination crack propagation. The results are used to extract the energy release rate, G, of the laminates with an insert film starter defect. The effect of the starter defect on the magnitude of G was examined using the CFRP composite sample with a Mode II delamination pre-crack. The higher magnitude of G for the sample with insert film starter defect was attributed to the initial straight geometry of the notch/interface crack and the toughness of the resin at the notch front of the fabricated film insert. The fractured sample was examined using a micro-computerized tomography scanner to establish the shape of the internal delamination crack front. Results revealed that the interface delamination propagated in a non-uniform manner, leaving a curved-shaped crack profile.
采用三点端部切口弯曲（3ENF）试验的实验方法，研究了单向碳纤维增强聚合物（CFRP）复合材料在剪切载荷（II型）作用下的损伤和断裂过程力学机制。CFRP复合材料由[0]组成，在中间平面有一个插入薄膜作为初始缺陷。对一个跨度为50毫米、界面分层裂纹长度为12.5毫米的3ENF试验样品进行测试，以得到载荷与变形响应。在最大力值处观察到的突然载荷下降表明分层裂纹扩展的开始。这些结果用于提取带有插入薄膜初始缺陷的层压板的能量释放率G。使用具有II型分层预裂纹的CFRP复合材料样品，研究了初始缺陷对G值大小的影响。带有插入薄膜初始缺陷的样品具有较高的G值，这归因于切口/界面裂纹的初始直线几何形状以及制造的薄膜插入物切口前端树脂的韧性。使用微型计算机断层扫描仪对断裂的样品进行检查，以确定内部分层裂纹前端的形状。结果表明，界面分层以不均匀的方式扩展，留下弯曲形状的裂纹轮廓。
