Ma Bin, Liu Shukui, Ma Zhanguo, Wang Qi-Ang, Yu Zibo
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China.
Department of Civil Engineering, The University of Nebraska at Lincoln, Omaha, NE 68182, USA.
Materials (Basel). 2022 Jun 24;15(13):4455. doi: 10.3390/ma15134455.
The expansion of cracks in 3D printing concrete materials may lead to structural failure, so it is essential to monitor crack propagation development. Coda wave interferometry (CWI) has been proven to be sensitive to microcracks, however, the evolution pattern of ultrasonic coda waves during crack growth is still not clear. This paper reports a numerical study of the sensitivity and feasibility of CWI for monitoring microcrack growth in heterogeneous materials. A two-phase concrete model, which contains microcracks with different angles and lengths, was developed using the finite element analysis software ABAQUS. The relative velocity change (Δv/v) and the decorrelation coefficient (Kd) at different crack increments were quantitatively analyzed. The numerical simulation results show that coda waves are sensitive to microcrack length as well as the crack angle. The Δv/v increases linearly with the increase of the length of a single microcrack, and the Kd could be linked to the crack length quadratically. Furthermore, a quantitative functional relationship between the CWI observations (Kd, Δv/v) and the angle of the crack to the source/receiver and the relative length growth of the crack are established. In addition, the nonlinear relationship between slope and angle can be fitted with a sinusoidal function. The reported results quantitatively assess the coda wave variation pattern during crack propagation, which is important for the promotion and application of CWI technology.
3D打印混凝土材料中裂缝的扩展可能会导致结构失效，因此监测裂缝的扩展发展至关重要。尾波干涉测量法（CWI）已被证明对微裂缝敏感，然而，裂缝扩展过程中超声尾波的演化模式仍不明确。本文报道了一项关于CWI监测异质材料中微裂缝扩展的敏感性和可行性的数值研究。使用有限元分析软件ABAQUS建立了一个包含不同角度和长度微裂缝的两相混凝土模型。对不同裂缝增量下的相对速度变化（Δv/v）和去相关系数（Kd）进行了定量分析。数值模拟结果表明，尾波对微裂缝长度以及裂缝角度都很敏感。Δv/v随单个微裂缝长度的增加呈线性增加，Kd与裂缝长度呈二次方关系。此外，建立了CWI观测值（Kd，Δv/v）与裂缝相对于源/接收器的角度以及裂缝相对长度增长之间的定量函数关系。另外，斜率与角度之间的非线性关系可用正弦函数拟合。所报道的结果定量评估了裂缝扩展过程中尾波的变化模式，这对CWI技术的推广和应用具有重要意义。
