Article
Materials Science, Ceramics
R. Vargas, R. B. Canto, F. Hild
Summary: This study proposes a method to estimate fracture energy from notch opening displacement (NOD) measurements when crack mouth opening displacements (CMODs) are not accessible. NODs and CMODs were calculated for two WST experiments on a castable refractory using digital image correlation (DIC) and finite element simulations. The results show that NOD data can effectively estimate crack propagation energy when CMODs cannot be measured.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2021)
Article
Materials Science, Ceramics
R. Vargas, R. B. Canto, F. Hild
Summary: This study provides a guideline on calibrating fracture parameters using notch opening displacements measured via digital image correlation and force data from wedge splitting tests. Weighted finite element model updating is applied to calibrate material and boundary condition parameters, resulting in very consistent numerical results.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2021)
Article
Engineering, Multidisciplinary
Liang Yang, Yongtao Yang, Hong Zheng, Zhijun Wu
Summary: The paper proposes an algorithm in which the values of phase field are used to identify crack paths, and physical patches are then cut by reconstructed crack paths to obtain explicit cracks and jump displacement field. The numerical examples demonstrate the predictions of various explicit cracks by the proposed method are in good agreement with literature, and Sneddon's example verifies the discontinuous displacement field across explicit cracks is consistent with the closed form solution. The proposed numerical model warrants further investigation.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Engineering, Mechanical
Taeseul Park, Asuka Kitahara, Toshiyuki Ishina, Shigeru Hamada, Hiroshi Noguchi
Summary: In this study, the current status of linear and nonlinear fracture mechanics was examined, and the requirements for elastic-plastic fracture mechanics (EPFM) as the next step in fracture mechanics were identified. The study proposed the use of imaginary crack tip opening displacement (I-CTOD) as a driving force for EPFM and conducted elastic-plastic finite element analyses of cracked solids in different work-hardened materials to understand the characteristics of the singular fields of elastic and plastic strains near a crack tip. It was found that I-CTOD represents the intensity of the singular fields of plastic strain, elastic strain, and imaginary plastic deformation near the crack tip in both plane stress and plane strain states. Therefore, I-CTOD shows promise as a mechanical driving force parameter for EPFM.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Chemistry, Physical
Jose Manuel Vasco-Olmo, Alonso Camacho-Reyes, Giancarlo Luis Gomez Gonzales, Francisco Diaz
Summary: This work uses the CJP model to investigate the plasticity-induced shielding effects on growing fatigue cracks and characterize the size and shape of the plastic zone. By analyzing displacement fields measured experimentally, the study successfully contributes to a better understanding of the shielding effects during fatigue crack growth.
Article
Chemistry, Physical
Hongbin Shang, Zhiyuan Lin, Hongli Gao, Xiaofeng Shan, Jingsong Zhan
Summary: This paper proposes a novel method for measuring dual microscopic fatigue-crack and tip-deformation-fields using a hybrid image-processing technique. The method is applied to research the physical short fatigue crack (SFC) closure effect and the evolution law of the tip deformation fields of Quenching-Partitioning (Q&P) steel during the crack-closure process. The method effectively solves the measurement problems associated with small crack tip regions, large deformation gradients, and strong material anisotropy. The results show that the stress ratio affects the crack-closure behavior and crack growth rate of Q&P steel in the physical SFC crack-growing stage. The research provides experimental and theoretical support for further studies on the SFC growth mechanism and fatigue life prediction of Q&P steel.
Article
Engineering, Multidisciplinary
Chang Ma, Zhoumo Zeng, Hui Zhang, Xiaobo Rui
Summary: DIC technology is widely used in measuring deformation, but its accuracy can be affected by discontinuous deformation in practical applications. This paper proposes a variable subset DIC algorithm that automatically selects the most suitable subset for matching under the guidance of a pixel-level ZNCC value distribution map, providing flexibility, applicability, and high precision.
Article
Engineering, Mechanical
A. Camacho-Reyes, F. V. Antunes, J. M. Vasco-Olmo, F. A. Diaz, L. A. Felipe-Sese
Summary: This study combines a novel differential geometry approach, 3D-DIC, and FEA results to characterize crack tip fields on curve-cracked elements. It aims to validate and compare aspects that cannot be addressed using 3D-DIC and provides a comprehensive comparison between experimental and numerical fields using an Image Decomposition technique.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Engineering, Marine
Jingjie Chen, Yanxian Chen, Yi Huang
Summary: This paper proposes an approach to determine crack opening stress (COS) based on the variable quantity of maximum crack opening displacement (VMCOD) considering thickness effect. The explicit expressions of the relationship between COS and VMCOD are derived through three-dimensional elastic-plastic finite element analysis, considering the effects of specimen thickness, crack length, stress ratio, Young's modulus, yield stress, and strain hardening. The relationships can be used to calculate the effective stress intensity factor range and predict crack growth rates for plates of different thicknesses, which show good correlation with experimental results.
Article
Construction & Building Technology
Lei Zhang, Jiayan Nie, Bin Shi, Heming Han, Jinghong Wu, Yifei Cui
Summary: Concrete structures are vulnerable to cracking due to temperature change, construction quality, and external force, which poses a significant threat to their safety. Distributed fiber optic sensing (DFOS) technology, with its advantages over traditional methods, has become widely used in detecting and monitoring concrete cracks. By analyzing strain peaks and integrating strain exerted on optical cables, the location and width of cracks can be determined. However, when the spacing between neighboring cracks is small, strain induced by cracks may overlap and lead to a saddle-shaped double strain peak, making it challenging to calculate the crack opening displacement (COD). To address this issue, an analytical method based on the shear strain transfer mechanism is proposed, and its effectiveness is verified through crack simulation experiments and concrete beam loading tests using optical frequency domain reflectometry (OFDR) technology for strain recording. The proposed method provides a feasible approach to calculate the COD of neighboring cracks with strain overlap.
CONSTRUCTION AND BUILDING MATERIALS
(2023)
Article
Chemistry, Physical
Muhammad Ajmal, Cristina Lopez-Crespo, Alejandro S. Cruces, Pablo Lopez-Crespo
Summary: This study presents a novel approach to investigate fatigue-induced crack growth by using the plastic contribution of crack-tip opening displacement (CTODp). CTODp is employed to predict the crack propagation in austenitic stainless-steel. Unlike linear elastic fracture mechanics analysis, this method is useful for tasks beyond small-scale yielding. The approach is based on correlating full-field displacement information with post-processing digital images. A detailed post-processing protocol is described to calculate CTODp, and the results for steel compact-tension specimens show promising findings, as there is a linear relationship between the propagation rate of fatigue cracks and the CTODp range.
Article
Engineering, Mechanical
Ilari Tillikainen, Pasquale Gallo, Pauli Lehto, Heikki Remes
Summary: The study investigates the relationship between crack growth rate (CGR) and cyclic crack-tip opening displacement (ΔCTOD) of microstructurally small fatigue cracks using high-resolution digital image correlation (DIC). Load-controlled fatigue tests were performed on small-scale specimens of 18%Cr ferritic stainless steel. The findings reveal that the non-linear relationship between CGR and ΔCTOD on a double logarithmic scale is caused by the crack-tip bypassing an inhomogeneous shear strain localization zone. ΔCTOD is not able to characterize the behavior of microstructurally small fatigue cracks within this zone, but remains a valid crack driving force parameter outside it.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2023)
Article
Engineering, Civil
Myung Soo Kang, Seok Been Im, Yun-Kyu An
Summary: The paper introduces crack opening phenomenon evaluation using digital image correlation (DIC) with a statistically optimized subset size. A new statistical optimization algorithm of the subset size is proposed, which calculates the optimal subset size by the 3-loop iteration of normalized cross correlation within the entire region of interest (ROI). The validation test results show significantly lower maximum error compared to a conventional subset size determination algorithm-based DIC analysis.
SMART STRUCTURES AND SYSTEMS
(2021)
Article
Engineering, Mechanical
Simon Lubich, Carl Fischer, Simon Schilli, Thomas Seifert
Summary: In this paper, the effect of the polycrystalline microstructure on crack-tip opening displacement and crack closure is investigated. It is found that the crack opening stress and cyclic crack-tip opening displacement are significantly influenced by the local grain structure, and the differences in the cyclic crack opening displacement are attributed to the asymmetric plastic strain fields in the plastic wake behind the crack-tip of the microstructure-based model.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Engineering, Marine
Yuelin Song, Ping Yang, Tian Xia, Ziya Peng, Jiping Zhang
Summary: This study aims to investigate the low-cycle fatigue crack growth behavior of EH-36 steel by analyzing crack opening displacement and proposing a simple method to calculate the crack growth rate. The crack tip opening displacement is described by a theoretical formula that considers accumulative strain and crack closure. Quantitative load tests on LCF crack growth of EH-36 steel are conducted to examine the variation of accumulative strain, crack opening displacement, and crack growth life. By fitting and verifying the test data, the relationship between crack opening displacement and crack growth rate is obtained. The proposed calculation formula effectively characterizes and predicts the crack growth behavior of EH-36 steel under low-cycle fatigue regimes.