Sunaga Daiki, Koba Takumi, Kanakubo Toshiyuki
Department of Engineering Mechanics and Energy, University of Tsukuba, 1 Chome Tennodai, Ibaraki 305-8573, Japan.
Materials (Basel). 2021 Jan 2;14(1):179. doi: 10.3390/ma14010179.
Tensile performance of fiber-reinforced cementitious composite (FRCC) after first cracking is characterized by fiber-bridging stress-crack width relationships called bridging law. The bridging law can be calculated by an integral calculus of forces carried by individual fibers, considering the fiber orientation. The objective of this study was to propose a simplified model of bridging law for bundled aramid fiber, considering fiber orientation for the practical use. By using the pullout characteristic of bundled aramid fiber obtained in the previous study, the bridging laws were calculated for various cases of fiber orientation. The calculated results were expressed by a bilinear model, and each characteristic point is expressed by the function of fiber-orientation intensity. After that, uniaxial tension tests of steel reinforced aramid-FRCC prism specimens were conducted to obtain the crack-opening behavior and confirm the adaptability of the modeled bridging laws in crack-width evaluation. The experimental parameters are cross-sectional dimensions of specimens and volume fraction of fiber. The test results are compared with the theoretical curves calculated by using the modeled bridging law and show good agreements in each parameter.
纤维增强水泥基复合材料（FRCC）首次开裂后的拉伸性能由称为桥接定律的纤维桥接应力-裂缝宽度关系表征。考虑纤维取向，桥接定律可通过对单根纤维所承受的力进行积分计算得出。本研究的目的是针对束状芳纶纤维提出一种简化的桥接定律模型，考虑纤维取向以用于实际应用。通过使用前期研究中获得的束状芳纶纤维的拔出特性，针对各种纤维取向情况计算桥接定律。计算结果用双线性模型表示，每个特征点用纤维取向强度的函数表示。之后，对钢纤维增强芳纶-FRCC棱柱体试件进行单轴拉伸试验，以获得裂缝张开行为并确认所建桥接定律模型在裂缝宽度评估中的适用性。试验参数为试件的横截面尺寸和纤维体积分数。将试验结果与使用所建桥接定律模型计算得到的理论曲线进行比较，各参数均显示出良好的一致性。
