scholarly journals Assessment of Acoustic Emission and Triaxial Mechanical Properties of Rock-Cemented Tailings Matrix Composites

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Shuai Cao ◽  
Erol Yilmaz ◽  
Weidong Song ◽  
Gaili Xue
Keyword(s):  
Acoustic Emission ◽  
Mechanical Strength ◽  
Failure Modes ◽  
Failure Process ◽  
Development Stage ◽  
Test System ◽  
Energy Reserve ◽  
Strengthening Effect ◽  
Matrix Composites ◽  
Damage Development

Acoustic emission (AE) test is a powerful technique for examining the sounds of cracks growing, breaking, and other modes of damage in cementitious materials deforming under stress, such as rock-cemented tailings matrix composites (RCTMC). RCTMC, an engineered mixture of tailings, cement, rock, and water, is widely used to fulfill numerous important roles at underground mine sites as a construction material and a ground support tool. To study the mechanical strength and AE properties of RCTMC, compression testing was carried out using a triaxial compression test system (TAW-2000) and AE monitoring system (PCI-2), and the failure modes of samples were also examined. Results have shown that (1) the failure process of RCTMC samples can be divided into six main stages: compaction, linear elastic characteristic, crack growth, primary damage development, cemented tailings backfill withstand stress zone, and secondary damage development stage. CTB has the strengthening effect on mechanical strength of rock; (2) the AE process can be also divided into six main stages: the prepeak quiescence period, the elastic energy reserve period, the first destruction development AE area, the secondary energy reserve period, the second damage development stage, and the postpeak calm period; and (3) samples’ cumulative ring count is “stepped” distribution over time, and the ring count has entered the postpeak flat stage after many active periods. The process of RCTMC samples from tensile to shear failure mode is represented by numerical simulation. Finally, the obtained experimental results can offer a useful reference for the further study of the mechanism of the surrounding rock and cemented tailings backfill structure.

scholarly journals Research on Failure Characteristics of Concrete Three-Point Bending Beams with Preexisting Cracks in Different Positions Based on Numerical Simulation

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Liuqun Zhao ◽  
Li Zheng ◽  
Hui Qin ◽  
Tiesuo Geng ◽  
Yonggang Tan ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Failure Process ◽  
Engineering Application ◽  
Tensile Failure ◽  
Engineering Structures ◽  
Failure Characteristics ◽  
Three Point Bending ◽  
Wide Range

Concrete three-point bending beams with preexisting cracks are widely used to study the growth process of I-II mixed mode cracks. Studying the failure characteristics of preexisting cracks at different locations on concrete three-point bending beams not only has important scientific significance but also has a wide range of engineering application backgrounds in the safety assessment of engineering structures. In this paper, through several numerical experiments, the influence of preexisting cracks at different positions on the failure characteristics of concrete three-point bending beams is studied, and three typical failure modes are obtained. The failure process of the specimens with three typical failure modes is discussed in detail, and it is pointed out that the crack failure mode is tensile failure. The change trends of bearing capacity, acoustic emission quantity, and acoustic emission energy of three typical failure modes are analyzed. The maximum bearing capacity, the maximum acoustic emission quantity, and energy of three failure modes of concrete three-point bending beams generally show an increasing trend.

Acoustic Emission Characteristics of Rock Failure under Uniaxial Loading

2011 ◽  
Vol 378-379 ◽  
pp. 43-46 ◽  
Author(s):  
Tao Xie ◽  
Qing Hui Jiang ◽  
Rui Chen ◽  
Wei Zhang
Keyword(s):  
Acoustic Emission ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Progressive Failure ◽  
Failure Process ◽  
Testing Machine ◽  
Rock Failure ◽  
Rock Failure Process ◽  
State Variation ◽  
Acoustic Emission Test

With RMT-150C rock testing machine and AEWIN E1.86 DISP acoustic emission system applied, the acoustic emission test was accomplished with two kinds of rock samples including marble and granite under uniaxial compression. Cyclic loading and continuous loading were used through the experiment, and the mechanical performance and acoustic emission (AE) characteristics were obtained during the process of rock progressive failure. Details related to the relationship between amount of AE and stress-strain was given in this paper. A comparison between marble and granite was made as well following the general AE law, on the basis of which, the failure mechanism of rock mass was investigated. Finally, some conclusions can be summarized as follows:(1) AE activity features are different with stress state variation in rock failure process;(2) loading patterns make a direct impact on the failure process thereby affecting AE activities;(3)AE activities are various basing on the different types of rocks, structures and failure modes.

scholarly journals Effect of Filling Interval Time on Long-Term Mechanical Strength of Layered Cemented Tailing Backfill

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Shuai Cao ◽  
Wei-dong Song
Keyword(s):  
Compressive Strength ◽  
Mechanical Strength ◽  
Failure Modes ◽  
Shear Failure ◽  
Development Stage ◽  
Stability Control ◽  
Tensile Failure ◽  
Uniaxial Compression Test ◽  
Linear Elastic ◽  
Shear Mixing

To explore the influence that filling interval has on the mechanical strength of layered cemented tailing backfill (LCTB), uniaxial compression test is conducted on LCTB samples with a concentration of 70%, 72%, and 75% and a filling interval of 12 h, 24 h, 36 h, and 48 h. From the tests above, mechanical properties and failure modes of LCTB are acquired. The results are as follows: (1) The peak compressive strength of LCTB decreases as the filling interval increases, and it increases when the concentration grows with a certain length of filling interval. At the same time, the peak compressive strength and filling interval show polynomial distribution. (2) There are four stages during the loading process of cemented backfill specimen, that is, compression stage, linear elastic stage, crack extension stage, and undermines development stage. As the filling interval increases, CTB shows a failure mode of tensile failure-tensile shear failure transition-tensile and shear mixing destruction, which provides a theoretical basis for strength design and stability control of backfill.

A Review on Mechanical and Acoustic Emission Behavior of Basalt Fiber Reinforced Composites

2018 ◽  
Vol 1148 ◽  
pp. 37-42
Author(s):  
Vemu Vara Prasad ◽  
Tanna Eswara Rao
Keyword(s):  
Acoustic Emission ◽  
Polymer Matrix ◽  
Failure Modes ◽  
Natural Fiber ◽  
Polymer Matrix Composites ◽  
Basalt Fiber ◽  
Fiber Reinforced Composites ◽  
Matrix Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced

Now a day’s eco-friendly natural fiber used as the reinforcement for the fabrication of the light weight, lower cost and biodegradable polymer matrix composites. One of such available natural reinforcement for the composite material is basalt fiber. The present paper gives a review on how the basalt fiber reinforced polymer matrix composite behave when they are adhesively, riveted and hybrid joined with other reinforcements such as aluminum, which is used for the particular or other applications and which joint gives better efficiency , suited for given application were discussed and the three joining techniques were investigated. Behavior of basalt fiber reinforced composites for the frequencies at which frequencies the failures like adhesive failure, light fiber tear, and mixed failure modes will occur. These three types of failure modes are investigated with the help of acoustic emission monitoring system.

scholarly journals Acoustic Emission and Failure Modes for Coal-Rock Structure under Different Loading Rates

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Ning Wang ◽  
Yingqian Xu ◽  
Dengyuan Zhu ◽  
Nan Wang ◽  
Benfu Yu
Keyword(s):  
Acoustic Emission ◽  
Energy Release ◽  
Failure Modes ◽  
Loading Rate ◽  
Failure Process ◽  
Coal Mass ◽  
Transient Growth ◽  
Loading Rates ◽  
Rock Structure ◽  
Coal Rock

Coal bump refers to a sudden catastrophic failure of coal seam and usually causes serious damages to underground mining facilities and staff. Considering the combined coal-rock structure for coal bumps, failure process and acoustic emission (AE) characteristics of combined coal-sandstone samples under different loading rates were studied by uniaxial compression tests, and three basic failure modes and bump proneness for coal-rock structure were obtained. The following conclusions are drawn: (1) when loading rate was relatively low, plastic deformation of coal mass fully developed, while surface cracks of coal mass was not apparent and slip along the transfixion crack occurred in the postpeak stage; (2) with the increase in loading rate, surface tensile cracks developed into splitting cracks at the end of the prepeak stage and throughout the postpeak stage, and brittle failure finally happened due to the release of nonlinear step-shaped energy or one-time strain energy release of upper rock mass, resulting in the damage of internal bearing structure and weakening of bearing capacity; (3) the deformation and failure process of combined samples showed obvious phases, and corresponding AE energy release rate could be divided into periodic linear growth and transient growth, while the cumulative energy of AE events has multiple peak points and transient growth with the increase of loading rate; (4) it was demonstrated that two distinct frequency bands existed in AE events, which were about 50 kHz and 150 kHz, and the distribution of AE events near 50 kHz was larger and stronger, representing the main frequency range of cracks in coal mass. According to the damage characteristics and AE parameters for combined samples, an brittle model for coal-rock structure with mutation characteristics was proposed, and three basic failure modes for the combined structure with the increase of loading rate were progressive shear failure, splitting failure, and structural failure, respectively.

scholarly journals Rock Stability Assessment Based on the Chronological Order of the Characteristic Acoustic Emission Phenomena

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Penghai Zhang ◽  
Tianhong Yang ◽  
Tao Xu ◽  
Qinglei Yu ◽  
Jingren Zhou ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Failure Process ◽  
High Energy ◽  
Development Stage ◽  
Crack Development ◽  
Stability Assessment ◽  
Chronological Order ◽  
Granitic Gneiss ◽  
High Energy Level ◽  
Rock Stability

Sudden inelastic deformations in rock are associated with acoustic emission (AE). Therefore, AE monitoring technique can be used to study the fracture processes of rock. In this paper, AE tests were conducted on the granitic gneiss specimens under the uniaxial compressive loading conditions. The temporal changes in AE hit parameters and spatial-temporal evolution of AE events during the failure process of the granitic gneiss specimens were studied, and several characteristic AE phenomena (i.e., dramatic increase in dominant frequency, AE energy, and hit rate, the AE event with a high energy level, and the through-going distribution of the AE events with intermediate energy levels) were statistically analyzed before the failure occurred. It was found that the chronological order of the characteristic AE phenomena was relatively certain and correspondingly had a close relationship with the crack development stage. Because of the difference of the stress level at each crack development stage, the stability at different crack development stages is different. Therefore, a rock stability assessment approach was established based on the chronological order of the characteristic AE phenomena, and then the rock stability was assessed using the proposed approach.

Study on Acoustic Emission and Failure Modes of Rock in Uniaxial Compression Test

2011 ◽  
Vol 261-263 ◽  
pp. 1393-1400
Author(s):  
Ji Liang Zhang ◽  
Chang Hong Li
Keyword(s):  
Compressive Strength ◽  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Compression Test ◽  
Failure Modes ◽  
Soft Rock ◽  
Development Stage ◽  
Uniaxial Compression Test ◽  
Whole Process ◽  
Shear Rupture

Based on uniaxial compression test, the mechanical properties and acoustic emission characteristics of rock had been obtained, including the relationship between AE and time, AE and stress level, and so on, in the whole process of rock failure. Research shows AE rate of rock has the subparagraph features obviously. There are three obvious AE sections for the higher strength elastic-brittle rock: First section is compaction stage, corresponding stress is 10% of compressive strength of rock; Second section is crack-development stage, corresponding stress is 80% of compressive strength; Third section is rupture stage, corresponding stress is the compressive strength. Furthermore, AE signals for the rupture stage is strongest. The law is still correct in cycle loading conditions. However, the subparagraph phenomenon isn’t clear for elastic-plastic rock, and the AE peak is lagging behind the ultimate strength of rock, the AE signal in the decline stage of strength is the most intensive and strong. The lagging phenomenon is due to X-shear rupture model of soft rock. The significant stress concentration in cone tip between the two relative extrusion cones leads to local rock broken seriously. Then, many acoustic signals have been observed.

scholarly journals Experimental and Numerical Studies on the Dynamic Behaviors of Concrete Material Based on the Waveform Features in SHPB Test

2018 ◽  
Vol 183 ◽  
pp. 01001
Author(s):  
Xiao Weintu Chen ◽  
Taihong Lv ◽  
Gang Chen
Keyword(s):  
Failure Modes ◽  
Split Hopkinson Pressure Bar ◽  
Failure Process ◽  
Scale Model ◽  
Hopkinson Pressure Bar ◽  
Damage Development ◽  
Concrete Material ◽  
Deformation And Failure ◽  
Failure Patterns ◽  
Shpb Test

The tendency of the waveform curve can directly reflect the deformation and failure process of specimen in the SHPB (Split Hopkinson Pressure Bar) test of concrete. Different loading rates will result in the different ultimate failure modes, waveform curves. Furthermore, these differences are obviously characterized by some feature points of waveform or stress-strain curves. It is to say for concrete-like damage softening materials, the waveform features contains lots of information of material response. In this study, large dimension (Ф120mm) SHPB tests of concrete specimens have been conducted. Four typical failure patterns of concrete specimens are classified, as well as some typical waveform features, e.g. the “double-peak” and“compression wave” phenomena of reflection wave, etc. On the other hand, the numerical simulations corresponding to the experimental tests are performed by means of the 3D meso-scale model of concrete material. In the numerical results, waveform features observed in experiment are reliably reproduced and predicted. Associating with waveform features, the violation indicator of the specimen stress equilibrium in the SHPB test is first identified for concrete-like damage softening materials. The concrete material behaviors forstress non-equilibrium are further analyzed, e.g. DIF and damage development, etc.

Failure characterization of PLA parts fabricated by fused deposition modeling using acoustic emission

2020 ◽  
Vol 26 (7) ◽  
pp. 1177-1182
Author(s):  
Feng Li ◽  
Zhonghua Yu ◽  
Zhensheng Yang
Keyword(s):  
Acoustic Emission ◽  
Fused Deposition Modeling ◽  
Failure Modes ◽  
Failure Process ◽  
Acoustic Emissions ◽  
Peak Frequency ◽  
Monitoring Method ◽  
Content Type ◽  
Fused Deposition ◽  
Deposition Modeling

Purpose This paper aims to focus on investigating the failure mode of fused deposition modeling (FDM) fabricated parts by using acoustic emission (AE) technique. Design/methodology/approach Considering the special prototyping way of FDM, the failure modes of FDM-fabricated parts were investigated experimentally. One test was carried out and the other two describe what has been observed on this basis. Acoustic emissions are obtained during the tensile process. AE features of peak frequency, energy and amplitude are extracted and preliminarily analyzed. Then, the unsupervised clustering method of k-means is applied to explore the relationship between the failure modes and the AE signals. Findings Failure modes of filament debonding and breakage can be successfully recognized by the pattern recognition technique of k-means. Practical implications The results obtained can help us understand the failure process of FDM printed parts. This will provide an available monitoring method in the application of FDM-fabricated parts. Originality/value This paper has investigated and characterized the failure modes of FDM fabricated parts for the first time.

scholarly journals Acoustic Emission Characteristics and Damage Evolution of Rock under Different Loading Modes

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3649
Author(s):  
Ersheng Zha ◽  
Ru Zhang ◽  
Zetian Zhang ◽  
Ting Ai ◽  
Li Ren ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Fracture Surface ◽  
Tensile Stress ◽  
Energy Release ◽  
Failure Modes ◽  
Failure Process ◽  
Tensile Tests ◽  
Single Fracture ◽  
Loading Modes ◽  
Ae Signals

To study the evolution of acoustic emission (AE) parameters and the differences in the fracturing and failure process of rocks under different loading modes, AE signals of marble were detected during uniaxial compression tests (UCTs), direct tensile tests (DTTs) and indirect tensile tests (ITTs) in this paper. Then, the temporal and spatial evolution of the AE parameters and damage development of rock under different loading modes were analyzed. The results showed that the sequence of total AE events and AE counts under different loading modes was UCT > DTT > ITT. In the DTT and ITT, the energy release of AE signals was concentrated at the peak stress and weakened rapidly afterward, whereas in the UCT, there were still a large number of AE signals accompanied by violent AE energy release during the postpeak stage. The generation mechanism of AE sources in rock and the corresponding failure modes were different under different loading modes. In the UCT, the multiple cleavage fractures were mainly caused by compression-induced fracturing. In the DTT, the single fracture surface was generated by tensile stress, whereas in the ITT, compressive-tensile stress was applied to the fracture surface. In addition, the stress levels at which the b-value and the spatial fractal dimension Ds of AE events decreased dramatically were consistent under the different loading modes, and the sequence was UCT < DTT < ITT. According to the changes in AE parameters during the whole process of rock deformation and failure, the first and second precursor points before failure were defined to distinguish the development of microfracture damage and failure processes in rocks under the different loading modes. The above results have certain significance for future studies on the monitoring of surrounding rock instability and failure prediction.

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