Kim Eui-Hyun, Lee Hyunbae, Kim Jae-Hwan, Bae Seung-Muk, Hwang Heesu, Yang Heesun, Choi Eunsoo, Hwang Jin-Ha
Department of Materials Science and Engineering, Hongik University, Seoul 04066, Korea.
Center for Research Facilities, Kunsan National University, Kunsan 54150, Korea.
Materials (Basel). 2018 Feb 22;11(2):315. doi: 10.3390/ma11020315.
Self-healing is an essential property of smart concrete structures. In contrast to other structural metals, shape memory alloys (SMAs) offer two unique effects: shape memory effects, and superelastic effects. Composites composed of SMA wires and conventional cements can overcome the mechanical weaknesses associated with tensile fractures in conventional concretes. Under specialized environments, the material interface between the cementitious component and the SMA materials plays an important role in achieving the enhanced mechanical performance and robustness of the SMA/cement interface. This material interface is traditionally evaluated in terms of mechanical aspects, i.e., strain-stress characteristics. However, the current work attempts to simultaneously characterize the mechanical load-displacement relationships synchronized with impedance spectroscopy as a function of displacement. Frequency-dependent impedance spectroscopy is tested as an in situ monitoring tool for structural variations in smart composites composed of non-conducting cementitious materials and conducting metals. The artificial geometry change in the SMA wires is associated with an improved anchoring action that is compatible with the smallest variation in resistance compared with prismatic SMA wires embedded into a cement matrix. The significant increase in resistance is interpreted to be associated with the slip of the SMA fibers following the elastic deformation and the debonding of the SMA fiber/matrix.
自修复是智能混凝土结构的一项基本特性。与其他结构金属不同，形状记忆合金（SMA）具有两种独特效应：形状记忆效应和超弹性效应。由SMA丝和传统水泥组成的复合材料能够克服传统混凝土中与拉伸断裂相关的力学弱点。在特定环境下，胶凝成分与SMA材料之间的材料界面对于实现SMA/水泥界面增强的力学性能和坚固性起着重要作用。传统上，这种材料界面是从力学方面，即应变 - 应力特性来评估的。然而，当前的研究试图同时表征与阻抗谱同步的机械载荷 - 位移关系，并将其作为位移的函数。频率相关的阻抗谱被测试作为一种原位监测工具，用于监测由非导电胶凝材料和导电金属组成的智能复合材料的结构变化。与嵌入水泥基体的棱柱形SMA丝相比，SMA丝中人为的几何形状变化与一种改进的锚固作用相关，这种锚固作用与最小的电阻变化相匹配。电阻的显著增加被解释为与SMA纤维在弹性变形后的滑动以及SMA纤维/基体的脱粘有关。
