Progressive failure characteristics and energy accumulation of granite with a pre-fabricated fracture during conventional triaxial loading

2021 ◽  
pp. 103219
Author(s):  
Yi Luo ◽  
Hangli Gong ◽  
Kun Xu ◽  
Chenhao Pei ◽  
Xiaoqing Wei ◽  
...  
Keyword(s):  
Progressive Failure ◽  
Triaxial Loading ◽  
Failure Characteristics ◽  
Energy Accumulation

Numerical Investigation of Post Buckling Strength and Failure Modes in Advanced Grid Stiffened Structure under Thermal-Mechanical Loads

2007 ◽  
Vol 334-335 ◽  
pp. 613-616
Author(s):  
Rui Xiang Bai ◽  
Bo Chen ◽  
Cheng Yan ◽  
Lin Ye ◽  
Ze Cheng Li ◽  
...  
Keyword(s):  
Failure Modes ◽  
Mechanical Load ◽  
Progressive Failure ◽  
Shear Deformation Theory ◽  
Failure Behavior ◽  
Linear Deformation ◽  
Failure Characteristics ◽  
Buckling Strength ◽  
Stiffened Structures ◽  
Post Buckling

This work investigated the post buckling strength and failure behavior of advanced grid stiffened structures (AGS) under thermal-mechanical load using a finite element method. Based on the first order shear deformation theory (FSDT), Von Karman non-linear deformation assumption, and a progressive failure criterion, the buckling, large deformation，local failure modes in the AGS were studied. The thermal effect was also analyzed. By some numerical examples, the failure characteristics of the AGS were discussed.

scholarly journals Progressive Failure Characteristics of Brittle Rock under High-Strain-Rate Compression Using the Bonded Particle Model

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3943 ◽  
Author(s):  
Xiaolin Huang ◽  
Shengwen Qi ◽  
Bowen Zheng ◽  
Songfeng Guo ◽  
Ning Liang ◽  
...  
Keyword(s):  
Strain Rate ◽  
High Strain ◽  
Progressive Failure ◽  
Brittle Rock ◽  
Particle Model ◽  
Failure Characteristics ◽  
Bonded Particle Model ◽  
Intact Sample ◽  
Micro Cracks ◽  
Strain Rate Compression

This paper microscopically investigated progressive failure characteristics of brittle rock under high-strain-rate compression using the bonded particle model (BPM). We considered the intact sample and the flawed sample loaded by split Hopkinson pressure bar respectively. Results showed that the progressive failure characteristics of the brittle rock highly depended on the strain rate. The intact sample first experienced in microcracking, then crack coalescing, and finally splitting into fragments. The total number of the micro cracks, the proportion of the shear cracks, the number of fragments and the strain at the peak stress all increased with the increasing strain rate. Also, a transition existed for the failure of the brittle rock from brittleness to ductility as the strain rate increased. For the flawed sample, the microcracking initiation position and the types of the formed macro cracks were influenced by the flaw angle in the initial stage. However, propagation of these early-formed macro cracks were prohibited in the later stages. New micro cracks were produced and then coalesced into diagonal macro cracks which could all form ‘X’-shape failure configuration regardless of the incline angle of the flaw. We explored micromechanics on progressive failure characteristics of the brittle rock under dynamic loads.

Progressive failure characteristics of unidirectional FRP with fiber clustering

2021 ◽  
pp. 114880
Author(s):  
Xiaofei Pang ◽  
Fangchao Huang ◽  
Fulei Zhu ◽  
Shufeng Zhang ◽  
Yashun Wang ◽  
...  
Keyword(s):  
Progressive Failure ◽  
Failure Characteristics ◽  
Fiber Clustering

scholarly journals Experimental Investigations on the Progressive Failure Characteristics of a Sandwiched Coal-Rock System Under Uniaxial Compression

2019 ◽  
Vol 9 (6) ◽  
pp. 1195 ◽  
Author(s):  
Jinwen Bai ◽  
Guorui Feng ◽  
Zehua Wang ◽  
Shangyong Wang ◽  
Tingye Qi ◽  
...  
Keyword(s):  
Rock Specimen ◽  
Progressive Failure ◽  
Failure Process ◽  
Local Strain ◽  
Experimental Investigations ◽  
Rock System ◽  
Failure Characteristics ◽  
Coal Rock ◽  
Mining Design ◽  
Seam Mining

Overlapped residual coal pillars, together with the surrounding rock strata, play a combined bearing role in ultra-close multiple seam mining. Global stability of the whole bearing system is significant for the mining design, construction, and operation. Laboratory uniaxial compressive experiments for different kinds of sandwiched coal-rock specimens are carried out to investigate the progressive failure characteristics and mechanisms. Results show that: (1) The mechanical behavior of the sandwiched coal-rock specimen is mainly divided into four stages during the failure process. The response of the electrical resistivity and the evolution of acoustic emission (AE) energy are in good agreement with the mechanical behaviors at different stages, which are a reflection of the global failure characteristics of sandwiched specimens. (2) The distribution of AE events and the development of local strain can provide further insight into the local failure characteristics of coal elements or rock elements in sandwiched specimens. AE events are more likely to be generated in coal elements, which can propagate across coal-rock interfaces and induce damage to rock elements in a certain area. Similarly, the unbalanced deformation characteristics of coal elements and rock elements are apparently revealed in the progressive failure process. (3) Progressive failure of a sandwiched coal-rock specimen is closely associated with the interactions between the coal elements and rock elements. Initial failure usually appears in the coal elements. At this process, the recovery of elastic deformation and the output of strain energy are observed in the rock elements, which can accelerate the rupture of coal elements. In turn, the dynamic fracture energy generated in the rupture process of coal elements can propagate into rock elements and induce damage to rock elements a certain area. (4) The experimental results are helpful for maintaining the long-term stability of a sandwiched coal-rock system in ultra-close multiple seam mining.

scholarly journals Uniaxial Compression Creep Relaxation and Grading of Coal Samples via Tests on the Progressive Failure Characteristics

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Zuqiang Xiong ◽  
Changsheng Song ◽  
Chengdong Su ◽  
Xiaolei Wang ◽  
Cheng Wang ◽  
...  
Keyword(s):  
Uniaxial Compression ◽  
Yield Curve ◽  
Progressive Failure ◽  
Failure Process ◽  
Thin Sheet ◽  
Strain Curve ◽  
Mechanical Parameters ◽  
Creep Failure ◽  
Creep Tests ◽  
Failure Characteristics

An RMT-150B electrohydraulic servo testing system was used to perform uniaxial compression and uniaxial grading relaxation (creep) tests. The deformation, strength, and failure characteristics of the progressive failure process of coal samples under three loading modes were analyzed. The analysis results show that the prepeak stress-strain curve of the coal samples and the load relationships are not clear and that the whole compression process of coal still showed compression, elastic, yielding, and failure stages. The local stress drop characteristics during our relaxation creep grading tests showed no clear peak value and showed a yield curve with the shape of a conventional single plateau. The values of the mechanical parameters of axial compression were significantly higher than those obtained in the grade relaxation (creep) tests, which showed the mechanical parameters of coal samples with aging characteristics. In the relaxation (creep) tests, when the stress ratio was less than 70%, the relaxation (creep) characteristics of the sample were not clear. When the ratio of stress relaxation (creep) was more than 70% in the relaxation (creep) tests during displacement (stress) with a constant relaxation (creep) over the duration of the test, the evolution, development, and convergence of microcracks in the coal samples were observed. Relaxation (creep) stress was higher, failure duration was shorter, and the duration of failure was longer. For fully mechanized coal faces, increasing the support resistance and timely moving the support after coal cutting may prevent rib spalling accidents by reducing coal stress and exposure time in the front of the working face. Additionally, routine uniaxial compressive failures showed a simple form, having a clear tension-shear dual rupture surface. The staged relaxation creep failure testing of coal is more complex. The entire coal samples were divided into many thin-sheet debris via gradual collapse and shedding, and the number of cracks increased significantly, showing evident lateral expansion characteristics that are similar to the rib spalling characteristics in high coal mining working faces.

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