Application of Asymmetric Notched Semi-Circular Bending Specimen to Evaluate Mixed-Mode I-II Fracture Behaviors of Sandstone
In this paper, to investigate mixed-mode I-II fracture behaviors, three different asymmetric notched semi-circular bending specimens (ANSCB) were designed by adjusting the angle and the distance between supporting rollers to conduct asymmetric three-point bending tests. Several aid technologies, inc...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-06-01
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| Series: | Fractal and Fractional |
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| Online Access: | https://www.mdpi.com/2504-3110/6/6/336 |
| _version_ | 1797487314397560832 |
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| author | Gang Ma Jiangteng Li Xiang Zhou Lianying Zhang Peitao Qiu Yang Yu |
| author_facet | Gang Ma Jiangteng Li Xiang Zhou Lianying Zhang Peitao Qiu Yang Yu |
| author_sort | Gang Ma |
| collection | DOAJ |
| description | In this paper, to investigate mixed-mode I-II fracture behaviors, three different asymmetric notched semi-circular bending specimens (ANSCB) were designed by adjusting the angle and the distance between supporting rollers to conduct asymmetric three-point bending tests. Several aid technologies, including acoustic emission (AE), digital image correlation (DIC), crack propagation gauge (CPG), and scanning electron microscopy (SEM), was utilized to monitor and assess the fracture characteristic. Meanwhile, the fractal dimension of the fracture surface was assessed based on the reconstructed digital fracture surface. The results show that mixed-mode I-II ANSCB three-point bending fracture is a brittle failure with the characteristics of the main crack being rapidly transfixed and the bearing capacity decreasing sharply. Based on the DIC method, the whole fracture process consists of a nonlinear elastic stage, fracture process zone, crack initiation stage and crack propagation stage. The crack initiation is mainly caused by the tension-shear strain concentration at the pre-existing crack tip. At the microscale, the crack propagation path is always along the grain boundary where the resultant stress is weakest. According to the monitoring of the AE, it can be found that micro-tensile cracks are mainly responsible for the asymmetric three-point bending fracture. The data obtained by CPG suggest that the subcritical crack growth rate is positively correlated to the ultimate load. In addition, asymmetric loading leads to a coarser fracture surface, and thus a higher fractal dimension of the fracture surface. The current study can provide a better understanding of the mixed-mode I-II fracture behaviors of rock. |
| first_indexed | 2024-03-09T23:45:51Z |
| format | Article |
| id | doaj.art-7a0fdb2ab5814ce7bd030c5bf85a10c8 |
| institution | Directory Open Access Journal |
| issn | 2504-3110 |
| language | English |
| last_indexed | 2024-03-09T23:45:51Z |
| publishDate | 2022-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Fractal and Fractional |
| spelling | doaj.art-7a0fdb2ab5814ce7bd030c5bf85a10c82023-11-23T16:43:01ZengMDPI AGFractal and Fractional2504-31102022-06-016633610.3390/fractalfract6060336Application of Asymmetric Notched Semi-Circular Bending Specimen to Evaluate Mixed-Mode I-II Fracture Behaviors of SandstoneGang Ma0Jiangteng Li1Xiang Zhou2Lianying Zhang3Peitao Qiu4Yang Yu5School of Civil Engineering, Central South University, Changsha 410075, ChinaSchool of Resources and Safety Engineering, Central South University, Changsha 410083, ChinaSchool of Civil Engineering, Central South University, Changsha 410075, ChinaSchool of Civil Engineering, Xuzhou University of Technology, Xuzhou 221018, ChinaSchool of Civil Engineering, Xuzhou University of Technology, Xuzhou 221018, ChinaSchool of Civil Engineering, Xuzhou University of Technology, Xuzhou 221018, ChinaIn this paper, to investigate mixed-mode I-II fracture behaviors, three different asymmetric notched semi-circular bending specimens (ANSCB) were designed by adjusting the angle and the distance between supporting rollers to conduct asymmetric three-point bending tests. Several aid technologies, including acoustic emission (AE), digital image correlation (DIC), crack propagation gauge (CPG), and scanning electron microscopy (SEM), was utilized to monitor and assess the fracture characteristic. Meanwhile, the fractal dimension of the fracture surface was assessed based on the reconstructed digital fracture surface. The results show that mixed-mode I-II ANSCB three-point bending fracture is a brittle failure with the characteristics of the main crack being rapidly transfixed and the bearing capacity decreasing sharply. Based on the DIC method, the whole fracture process consists of a nonlinear elastic stage, fracture process zone, crack initiation stage and crack propagation stage. The crack initiation is mainly caused by the tension-shear strain concentration at the pre-existing crack tip. At the microscale, the crack propagation path is always along the grain boundary where the resultant stress is weakest. According to the monitoring of the AE, it can be found that micro-tensile cracks are mainly responsible for the asymmetric three-point bending fracture. The data obtained by CPG suggest that the subcritical crack growth rate is positively correlated to the ultimate load. In addition, asymmetric loading leads to a coarser fracture surface, and thus a higher fractal dimension of the fracture surface. The current study can provide a better understanding of the mixed-mode I-II fracture behaviors of rock.https://www.mdpi.com/2504-3110/6/6/336mixed-mode I-IIasymmetric notched semi-circular bendingthree-point bending testdigital image correlationfractal dimension |
| spellingShingle | Gang Ma Jiangteng Li Xiang Zhou Lianying Zhang Peitao Qiu Yang Yu Application of Asymmetric Notched Semi-Circular Bending Specimen to Evaluate Mixed-Mode I-II Fracture Behaviors of Sandstone Fractal and Fractional mixed-mode I-II asymmetric notched semi-circular bending three-point bending test digital image correlation fractal dimension |
| title | Application of Asymmetric Notched Semi-Circular Bending Specimen to Evaluate Mixed-Mode I-II Fracture Behaviors of Sandstone |
| title_full | Application of Asymmetric Notched Semi-Circular Bending Specimen to Evaluate Mixed-Mode I-II Fracture Behaviors of Sandstone |
| title_fullStr | Application of Asymmetric Notched Semi-Circular Bending Specimen to Evaluate Mixed-Mode I-II Fracture Behaviors of Sandstone |
| title_full_unstemmed | Application of Asymmetric Notched Semi-Circular Bending Specimen to Evaluate Mixed-Mode I-II Fracture Behaviors of Sandstone |
| title_short | Application of Asymmetric Notched Semi-Circular Bending Specimen to Evaluate Mixed-Mode I-II Fracture Behaviors of Sandstone |
| title_sort | application of asymmetric notched semi circular bending specimen to evaluate mixed mode i ii fracture behaviors of sandstone |
| topic | mixed-mode I-II asymmetric notched semi-circular bending three-point bending test digital image correlation fractal dimension |
| url | https://www.mdpi.com/2504-3110/6/6/336 |
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