Fracture initiation under pure shear revisited: Remarks on the mode II fracture in quasi-brittle materials
文献类型：期刊论文
| 作者 | Lin, Qing1,2; Wang, Siqi1,2; Pan, Peng-Zhi3; Ji, Wei-Wei2; Lu, Yunhu1,2 |
| 刊名 | THEORETICAL AND APPLIED FRACTURE MECHANICS
 |
| 出版日期 | 2020-10-01 |
| 卷号 | 109页码:24 |
| 关键词 | Pure shear mode II fracture Fracture kink digital image correlation (DIC) Shear influence Fracture criteria |
| ISSN号 | 0167-8442 |
| DOI | 10.1016/j.tafmec.2020.102700 |
| 英文摘要 | Mode II fracture, as one basic fracture mode, remains an interesting topic in fracture mechanics. However, its realization is a challenge in the laboratory, especially for quasi-brittle materials. In this study, two types of specimens were tested: the angled edge crack semi-circular specimen under three-point bending (SCB) and double edge notched compression (DENC) specimen. Digital image correlation (DIC) was used to measure the displacements surrounding the notch tip, which helps to identify the fracture mode. Based on experimental results, this study (i) confirms that a pure shear stress condition is achieved at the notch tip before the fracture initiation; (ii) shows that the initiated fractures are all mode I/opening fractures, not mode II/sliding fractures. More importantly, detailed experimental analyses demonstrate those mode I fractures are actually under the influence of shear load, but they are not the mixed-mode fractures. Experimental evidence is the observation of non-symmetric pattern of opening displacements. With the presence of a fracture process zone with a finite size, it is interesting to observe that shear load cannot produce a slip during fracture initiation, and only makes orthogonal displacements non-symmetric. The phenomenon represents a challenge to understand fracture initiation under large scale yielding. In this study a parameter eta( )is introduced, i.e., the ratio of opening displacements along two fracture surfaces, to quantitatively evaluate the influence of shear load. Although parameter eta does not present actual value of shear load, its value change indicates the change of shear load such that fundamental information about shear influence can be obtained. The study shows two different tendencies of parameter eta change during fracture initiation, which indicates the consequences of the SCB and DENC specimens. After examination of various fracture criteria, DIC comparisons of experimental results reveal an interpretation: (i) for the SCB specimen, pure shear condition cannot be maintained once fracture initiates, which refers to the "weak" condition. This "weak" condition creates a fracture initiation following the criterion of local symmetry, because the parameter eta changes from a finite value of larger than 1 to almost 1, suggesting local shear influence is gradually removed; (ii) for the DENC specimen, pure shear is maintained after fracture initiates, which refers to the "strong" condition. For the "strong" condition, parameter eta increases from a finite value of larger than 1 to an infinite value, which suggests shear influence increases, such that it does not obey prediction from most current fracture criteria such as MTS criterion. In addition, fracture pattern from the "weak" condition is quite simple; but the "strong" condition can result in a structural response so that a complex fracture pattern may be created. |
| 资助项目 | State Key Research Development Program of China[2017YFC0804203] ; National Natural Science Foundation of China[51304225] ; National Natural Science Foundation of China[51774305] ; National Science and Technology Major Project[2016ZX05051-003] |
| WOS研究方向 | Engineering ; Mechanics |
| 语种 | 英语 |
| WOS记录号 | WOS:000580995300024 |
| 出版者 | ELSEVIER |
| 源URL | [http://119.78.100.198/handle/2S6PX9GI/25019]  |
| 专题 | 中科院武汉岩土力学所 |
| 通讯作者 | Pan, Peng-Zhi |
| 作者单位 | 1.China Univ Petr, Coll Petr Engn, Beijing 102249, Peoples R China 2.China Univ Petr, State Key Lab Petr Resources & Prospecting, Beijing 102249, Peoples R China 3.Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China |
| 推荐引用方式 GB/T 7714 | Lin, Qing,Wang, Siqi,Pan, Peng-Zhi,et al. Fracture initiation under pure shear revisited: Remarks on the mode II fracture in quasi-brittle materials[J]. THEORETICAL AND APPLIED FRACTURE MECHANICS,2020,109:24. |
| APA | Lin, Qing,Wang, Siqi,Pan, Peng-Zhi,Ji, Wei-Wei,&Lu, Yunhu.(2020).Fracture initiation under pure shear revisited: Remarks on the mode II fracture in quasi-brittle materials.THEORETICAL AND APPLIED FRACTURE MECHANICS,109,24. |
| MLA | Lin, Qing,et al."Fracture initiation under pure shear revisited: Remarks on the mode II fracture in quasi-brittle materials".THEORETICAL AND APPLIED FRACTURE MECHANICS 109(2020):24. |
入库方式： OAI收割
来源：武汉岩土力学研究所
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