Sun Qingping, Zhou Guowei, Tang Haibin, Chen Zhangxing, Fenner Joel, Meng Zhaoxu, Jain Mukesh, Su Xuming
School of Intelligent Manufacturing, Nanjing University of Science and Technology, Nanjing 210094, China.
Department of Mechanical Engineering, McMaster University, Hamilton, ON L8S4L7, Canada.
Compos B Eng. 2021 Jun 15;215. doi: 10.1016/j.compositesb.2021.108803. Epub 2021 Mar 19.
In this study, integrated experimental tests and computational modeling are proposed to investigate the failure mechanisms of open-hole cross-ply carbon fiber reinforced polymer (CFRP) laminated composites. In particular, we propose two effective methods, which include width-tapered double cantilever beam (WTDCB) and fixed-ratio mixed-mode end load split (FRMMELS) tests, to obtain the experimental data more reliably. We then calibrate the traction-separation laws of cohesive zone model (CZM) used among laminas of the composites by leveraging these two methods. The experimental results of fracture energy, i.e. and , obtained from WTDCB and FRMMELS tests are generally insensitive to the crack length thus requiring no effort to accurately measure the crack tip. Moreover, FRMMELS sample contains a fixed mixed-mode ratio of / depending on the width taper ratio. Examining comparisons between experimental results of FRMMELS tests and failure surface of B-K failure criterion predicted from a curve fitting, good agreement between the predictions and experimental data has been found, indicating that FRMMELS tests are an effective method to determine mixed-mode fracture criterion. In addition, a coupled experimental-computational modeling of WTDCB, edge notched flexure, and FRMMELS tests are adopted to calibrate and validate the interfacial strengths. Finally, failure mechanisms of open-hole cross-ply CFRP laminates under flexural loading have been studied systematically using experimental and multi-scale computational analyses based on the developed CZM model. The initiation and propagation of delamination, the failure of laminated layers as well as load-displacement curves predicted from computational analyses are in good agreement with what we have observed experimentally.
在本研究中，提出了综合实验测试和计算建模方法，以研究开孔正交铺层碳纤维增强聚合物（CFRP）层合复合材料的失效机制。具体而言，我们提出了两种有效方法，包括宽度渐变双悬臂梁（WTDCB）和固定比例混合模式端载荷劈裂（FRMMELS）试验，以更可靠地获取实验数据。然后，我们利用这两种方法校准复合材料层间使用的内聚区模型（CZM）的牵引-分离定律。从WTDCB和FRMMELS试验获得的断裂能实验结果，即 和 ，通常对裂纹长度不敏感，因此无需精确测量裂纹尖端。此外，FRMMELS试样根据宽度渐变率包含固定的 / 混合模式比。通过检查FRMMELS试验的实验结果与曲线拟合预测的B-K失效准则的破坏面之间的比较，发现预测结果与实验数据之间具有良好的一致性，这表明FRMMELS试验是确定混合模式断裂准则的有效方法。此外，采用WTDCB、边缘切口弯曲和FRMMELS试验的实验-计算耦合建模来校准和验证界面强度。最后，基于所开发的CZM模型，通过实验和多尺度计算分析系统地研究了开孔正交铺层CFRP层合板在弯曲载荷下的失效机制。计算分析预测的分层的起始和扩展、层合板层的失效以及载荷-位移曲线与我们的实验观察结果吻合良好。
