Lim Taeuk, Cheng Hao, Hu Jie, Lee Yeongjun, Kim Sangyou, Kim Jangheon, Jung Wonsuk
School of Mechanical Engineering, Chungnam National University, Daejeon 34134, Republic of Korea.
Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1, Daejeon 34141, Republic of Korea.
Materials (Basel). 2023 Aug 18;16(16):5687. doi: 10.3390/ma16165687.
Studies on self-healing capsules embedded in cement composites to heal such cracks have recently been actively researched in order to improve the dimensional stability of concrete structures. In particular, capsule studies were mainly conducted to separately inject reactive healing solutions into different capsules. However, with this method, there is an important limitation in that the probability of self-healing is greatly reduced because the two healing solutions must meet and react. Therefore, we propose three-dimensional (3D) printer-based self-healing capsules with a membrane structure that allows two healing solutions to be injected into one capsule. Among many 3D printing methods, we used the fusion deposition modeling (FDM) to design, analyze, and produce new self-healing capsules, which are widely used due to their low cost, precise manufacturing, and high-speed. However, polylactic lactic acid (PLA) extruded in the FDM has low adhesion energy between stacked layers, which causes different fracture strengths depending on the direction of the applied load and the subsequent performance degradation of the capsule. Therefore, the isotropic fracture characteristics of the newly proposed four types of separated membrane capsules were analyzed using finite element method analysis. Additionally, capsules were produced using the FDM method, and the compression test was conducted by applying force in the x, y, and z directions. The isotropic fracture strength was also analyzed using the relative standard deviation (RSD) parameter. As a result, the proposed separated membrane capsule showed that the RSD of isotropic fracture strength over all directions fell to about 18% compared to other capsules.
为提高混凝土结构的尺寸稳定性，近年来人们积极开展了关于嵌入水泥复合材料中的自修复胶囊以修复此类裂缝的研究。特别是，胶囊研究主要是为了将反应性修复溶液分别注入不同的胶囊中。然而，采用这种方法存在一个重要的局限性，即由于两种修复溶液必须相遇并发生反应，自修复的概率会大大降低。因此，我们提出了一种基于三维（3D）打印的具有膜结构的自修复胶囊，该结构允许将两种修复溶液注入一个胶囊中。在众多3D打印方法中，我们使用熔融沉积建模（FDM）来设计、分析和生产新型自修复胶囊，该方法因其成本低、制造精确和速度快而被广泛使用。然而，FDM中挤出的聚乳酸（PLA）在堆叠层之间的粘附能较低，这导致根据施加负载的方向不同而具有不同的断裂强度，进而导致胶囊性能下降。因此，使用有限元方法分析了新提出的四种分离膜胶囊的各向同性断裂特性。此外，使用FDM方法制作了胶囊，并在x、y和z方向施加力进行压缩试验。还使用相对标准偏差（RSD）参数分析了各向同性断裂强度。结果表明，与其他胶囊相比，所提出的分离膜胶囊在所有方向上的各向同性断裂强度的RSD降至约18%。
