Hosoi Atsushi, Kawada Hiroyuki
Department of Applied Mechanics and Aerospace Engineering, Waseda University, Tokyo 169-8555, Japan.
Kagami Memorial Research Institute for Material Science and Technology, Waseda University, Tokyo 169-0051, Japan.
Materials (Basel). 2018 Jul 10;11(7):1182. doi: 10.3390/ma11071182.
Carbon fiber reinforced plastic (CFRP) laminates are used as main structural members in many applications. Transverse cracks that form in 90° layers of CFRP laminates are mostly initial damage in the case where tensile loading is vertically applied to the 90° layers of CFRP laminates, and they are the origin of more serious damage of delamination and fiber breakage. It is thus important to predict quantitatively the transverse crack initiation of CFRP laminates subjected to cyclic loading to ensure the long-term reliability of the laminates. The initiation and multiplication behaviors of transverse cracks strongly depend on the laminate configuration, thickness, and thermal residual stress. Therefore, a model based on the Walker model was proposed to predict transverse crack initiation in CFRP cross-ply and quasi-isotropic laminates under cyclic loading in the present study. The usefulness of the proposed model was verified with 10 different CFRP laminates formed from four different prepregs with epoxy resin matrices. The analysis results were in good agreement with experimental results. The fatigue life was expressed with three constants, which related to the fatigue strength reduction, the normalized fatigue strength at = 1 cycle, and the contribution of stress amplitude to the fatigue life, and they are independent of the laminate configuration.
碳纤维增强塑料（CFRP）层压板在许多应用中用作主要结构部件。在CFRP层压板的90°层中形成的横向裂纹，在拉伸载荷垂直作用于CFRP层压板的90°层的情况下，大多是初始损伤，并且它们是分层和纤维断裂等更严重损伤的起源。因此，定量预测承受循环载荷的CFRP层压板的横向裂纹萌生，对于确保层压板的长期可靠性很重要。横向裂纹的萌生和扩展行为强烈依赖于层压板的结构、厚度和热残余应力。因此，在本研究中提出了一种基于Walker模型的模型，用于预测循环载荷下CFRP正交铺层和准各向同性层压板中的横向裂纹萌生。用由四种不同的含环氧树脂基体的预浸料制成的10种不同的CFRP层压板验证了所提出模型的有效性。分析结果与实验结果吻合良好。疲劳寿命用三个常数表示，这三个常数与疲劳强度降低、在N = 1循环时的归一化疲劳强度以及应力幅对疲劳寿命的贡献有关，并且它们与层压板结构无关。
