scholarly journals A Numerical Research on Crack Process of Gypsum Containing Single Flaw with Different Angle and Length in Uniaxial Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Dai Bing ◽  
He Guicheng ◽  
Zhang Zhijun
Keyword(s):  
Numerical Simulations ◽  
Inclination Angle ◽  
Peak Strength ◽  
Uniaxial Loading ◽  
Reduction Degree ◽  
Cd Stress ◽  
Inclination Angles ◽  
Numerical Research ◽  
Single Flaw

To investigate the crack behaviour of rock or rock-like material in uniaxial loading, a series of numerical simulations were conducted on gypsum specimens containing a single flaw with different inclination angle (0°–90°) and length (10 mm–30 mm). Based on the numerical simulations results, the effect of flaw length on peak strength, the CI stress, and the CD stress were investigated with different inclination angles. The results show that the peak strength decreased initially and then increased with increasing of the flaw angle. Meanwhile, the peak strength decreased gradually when the length of the preexisting flaw increased. When the inclination angle was 30°, 45°, and 60°, the reduction degree of peak strength increased with increasing of the flaw length. The CI stress and CD stress not only depend on the inclination angle but also depend on flaw length. Four types of crack were observed in numerical simulations. The present research facilitates increased understanding of crack behaviour of rock under different conditions.

scholarly journals A Numerical Study on the Crack Development Behavior of Rock-Like Material Containing Two Intersecting Flaws

Mathematics ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 1223 ◽  
Author(s):  
Bing Dai ◽  
Ying Chen ◽  
Guoyan Zhao ◽  
Weizhang Liang ◽  
Hao Wu
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Numerical Simulations ◽  
Inclination Angle ◽  
Numerical Study ◽  
Peak Stress ◽  
Crack Coalescence ◽  
Intersection Angle ◽  
Crack Behavior ◽  
Inclination Angles

It is quite often that rocks contain intersecting cracks. Therefore, crack behavior cannot be completely studied by only considering several isolated, single flaws. To investigate the crack behavior of rock or rock-like material containing intersecting flaws under uniaxial loading, numerical simulations were carried out using parallel bonded-particle models containing two intersecting flaws with different inclination angles (varying β) and different intersection angles (varying αα). The crack propagation processes are analyzed and two typical patterns of linkage are observed between two intersecting flaws: (1) One-tip-linkage that contains three subtypes: Coalescence position near the tip; coalescence position at the flaw, but far away from the tip; coalescence position outside the flaw at a certain distance from the tip; and (2) two-tip-linkage with two subtypes: Straight linkage and arc linkage. The geometries of flaws influence the coalescence type. Moreover, the effects of intersection angle α and inclination angle β on the peak stress, the stress of crack initiation, and the stress of crack coalescence are also investigated in detail.

scholarly journals Experimental Investigations on Creep Behavior of Coal under Combined Compression and Shear Loading

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Rongbin Hou ◽  
Leige Xu ◽  
Duoxin Zhang ◽  
Yanke Shi ◽  
Luyang Shi
Keyword(s):  
Inclination Angle ◽  
Creep Test ◽  
Creep Behavior ◽  
Shear Loading ◽  
Peak Strength ◽  
Term Strength ◽  
Creep Tests ◽  
Inclination Angles ◽  
Pure Compression

The creep behavior of rock has received much attention for analyzing the long-term response and stability of underground rock engineering structures. Numerous studies have been carried out on the creep properties of various rocks under pure compression conditions. However, little attention has been paid to the creep behavior of rocks in a combined compression-shear loading state. In this work, a novel combined compression and shear test (C-CAST) system was used to carry out inclined uniaxial compression tests and creep tests for various inclination angles (0°, 5°, 10°, and 15°). The results revealed that the peak strength of the coal decreased with the inclination angle of the specimen, which could provide the basis for setting up a creep test scheme. Multistage compression-shear creep tests were carried out on specimens with different inclination angles. Based on the analysis of the creep test data, the creep behavior of the coal in a combined compression-shear state was studied. It was found that the specimen inclination affected the time-dependent deformation, long-term strength (LTS), and time to failure. Compared with the specimen under pure compression, the inclination specimens tend to produce large shear strain with time, while they were more prone to shear failure. The reduction of the long-term strength was closely associated with the increase of the specimen inclination angle when the angle was more than 5°. Moreover, the ratio of the peak strength to the LTS was not affected by the specimen inclination, which is considered an inherent characteristic. We anticipate that the results obtained will assist in pillar design and long-term stability analysis.

scholarly journals Acoustic Emission Characteristics and Joint Nonlinear Mechanical Response of Rock Masses under Uniaxial Compression

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 200
Author(s):  
Zhongliang Feng ◽  
Xin Chen ◽  
Yu Fu ◽  
Shaoshuai Qing ◽  
Tongguan Xie
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Inclination Angle ◽  
Failure Modes ◽  
Strain Curve ◽  
Particle Flow Code ◽  
Rock Masses ◽  
Physical Experiments ◽  
Inclination Angles ◽  
Joint Inclination

The joint arrangement in rock masses is the critical factor controlling the stability of rock structures in underground geotechnical engineering. In this study, the influence of the joint inclination angle on the mechanical behavior of jointed rock masses under uniaxial compression was investigated. Physical model laboratory experiments were conducted on jointed specimens with a single pre-existing flaw inclined at 0°, 30°, 45°, 60°, and 90° and on intact specimens. The acoustic emission (AE) signals were monitored during the loading process, which revealed that there is a correlation between the AE characteristics and the failure modes of the jointed specimens with different inclination angles. In addition, particle flow code (PFC) modeling was carried out to reproduce the phenomena observed in the physical experiments. According to the numerical results, the AE phenomenon was basically the same as that observed in the physical experiments. The response of the pre-existing joint mainly involved three stages: (I) the closing of the joint; (II) the strength mobilization of the joint; and (III) the reopening of the joint. Moreover, the response of the pre-existing joint was closely related to the joint’s inclination. As the joint inclination angle increased, the strength mobilization stage of the joint gradually shifted from the pre-peak stage of the stress–strain curve to the post-peak stage. In addition, the instantaneous drop in the average joint system aperture (aave) in the specimens with medium and high inclination angles corresponded to a rapid increase in the form of the pulse of the AE activity during the strength mobilization stage.

scholarly journals Experimental and Numerical Research on Cylindrical Tubes under Outer Cylindrical Explosive Waves

2017 ◽  
Vol 2017 ◽  
pp. 1-10
Author(s):  
Sui Yaguang ◽  
Zhang Dezhi ◽  
Tang Shiying ◽  
Chen Bo
Keyword(s):  
Numerical Methods ◽  
Numerical Simulations ◽  
Explosive Loading ◽  
Important Application ◽  
Uniform Deformation ◽  
Collision Region ◽  
Explosive Wave ◽  
Cylindrical Tubes ◽  
Numerical Research ◽  
Microscopic Deformation

Cylindrical explosive loading has an important application in explosive working, researching on weapon damage, and explosive-driving load. This study uses experimental and numerical methods to study the response of long and thin tubes when subjected to cylindrical explosive loading. The flake-like charge and multipoint initiation technique were adopted to load cylindrical explosive waves. Experimental results showed that the method could produce uniform deformation in certain parts of the long tube, but partial spall injuries occurred after the explosion. The macroscopic and microscopic deformation of tubes were analyzed. Numerical simulations were conducted to investigate the detailed response of the tube subjected to a cylindrical explosive wave. The results indicate that the collision of explosive waves brought inconsistencies in pressure and velocity. The pressure and velocity in the collision region were significantly higher than those of other parts, which caused the collision region to be easily damaged.

Experimental study and numerical simulation of uniaxial compression on artificial rock samples with Z-shaped fractures

2021 ◽  
Author(s):  
Tao Zhou ◽  
Haijun Chen ◽  
Liangxiao Xiong ◽  
Zhongyuan Xu ◽  
Jie Yang ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Crack Length ◽  
Uniaxial Compression ◽  
Inclination Angle ◽  
Failure Surface ◽  
Peak Strength ◽  
Particle Flow Code ◽  
Compression Tests ◽  
Failure Characteristics ◽  
Change Trend

Abstract To study the influence of the inclination and length of Z-shaped fissures on the mechanical properties and failure characteristics of the rock mass, this study conducts a series of uniaxial compression tests on rock-like materials with prefabricated Z-shaped fractures. In addition, two-dimensional Particle Flow Code software is used to perform uniaxial compression numerical simulations. The results show that when the specified inclination angle γ (γ = 0°, 30° or 45°) of the parallel cracks on both sides remains unchanged, the peak strength and elastic modulus of the sample show an M-shaped change trend with an increase in the inclination angle β of the middle connection crack. When γ = 60° or 90°, however, the peak strength and elastic modulus of the sample show a trend of decreasing, increasing, and then decreasing as β increases. In addition, the peak strength and elastic modulus of the sample decrease with an increase in the crack length. The influence of crack length on the elastic modulus is less than that of compressive strength. Further, the main failure mode of specimens with Z-shaped cracks is determined to be tension–shear mixed failure manifested by crack propagation from the tip of the prefabricated crack to the upper and lower boundaries of the sample. As a result, a through failure surface is formed with the prefabricated crack, which destroys the sample.

Aerodynamic effects of bio-inspired corrugated wings on gliding and hovering performances

2020 ◽  
pp. 095440622091799
Author(s):  
Haibin Xuan ◽  
Jun Hu ◽  
Yong Yu ◽  
Jiaolong Zhang
Keyword(s):  
Inclination Angle ◽  
Fluid Dynamic ◽  
Angle Of Attack ◽  
Aerodynamic Forces ◽  
Limited Effect ◽  
Gliding Flight ◽  
Significant Difference ◽  
Inclination Angles ◽  
Underlying Mechanisms ◽  
Lift And Drag

Recently, numerous studies have been conducted to clarify the effects of corrugation wing on aerodynamic performances. The effects of the corrugation patterns and inclination angles were investigated using computational fluid dynamic method in gliding and hovering flight at Reynolds numbers of order 104. The instantaneous aerodynamic forces and the vorticity field around the wing models were provided to research the underlying mechanisms of aerodynamic effects of corrugated wing models. The findings can be concluded as follows: (1) the corrugation patterns have different effects on aerodynamic performance. The effect of noncamber corrugated wing is to decrease the lift and increase drag compared with a flat-plate when the angle of attack is less than 25° during gliding flight. The corrugated wing with a camber (corrug-2) after the valleys enhances the aerodynamic forces when angle of attack is higher than 35°. The valley inclination angle has limited effect on aerodynamic forces in gliding flight. (2) The lift forces of different corrugation patterns show significantly asymmetric during the upstroke and downstroke. The main reason leads to this phenomenon is the case that two sides of the corrugated wings are not symmetric around the pitching axis. The corrugated wing with only two valleys (corrug-1) changes the lift and drag very slightly. Corrug-2 produces larger peak during downstroke and smaller peak during upstroke. The increase in the inclination angle has limited effect on the aerodynamic forces. The possible reason for these small aerodynamic effects might be that the corrugated wings are smoothed by small vortices trapped in valleys. The main reason for the significant difference between plate and corrug-2 is that the recirculating vortices trapped in the saddle and hump reduce the pressure above the wing surface.

Effect of Fluke Inclination on Behavior of Drag Anchor in Uniform Clay Under Unidirectional and Combined Loading

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Xiaoni Wu ◽  
Yean Khow Chow ◽  
Chun Fai Leung
Keyword(s):  
Inclination Angle ◽  
Promising Method ◽  
Combined Loading ◽  
Embedment Depth ◽  
Practical Case ◽  
Depth Ratio ◽  
Envelope Method ◽  
Inclination Angles ◽  
Selection Of ◽  
Shape And Size

Prediction of trajectory of drag anchor is important for the design and selection of drag anchor. Prediction based on yield envelope characterizing the anchor behavior under combined loading provides a promising method. However, the existing application of the yield envelope method ignores the effect of the fluke inclination angle by assuming a horizontally placed anchor fluke. This study aims to investigate the behavior of inclined fluke, which is the practical case during installation. The effects of the fluke inclination angle and embedment depth ratio on the anchor behavior in uniform clay under unidirectional loading and combined loading are investigated. It is found that the effect of the fluke inclination angle on the unidirectional capacity factors is mainly for anchor with embedment depth ratio less than 3. This results in the large difference of the size of the yield envelopes for fluke with same smaller embedment depth ratio but different fluke inclination angle, while the effect is minor on the shape of the yield envelope for such cases. However, there is large difference in the shape and size of the shallow yield envelopes for fluke with different embedment depth ratios and inclination angles.

scholarly journals Bayesian hierarchical inference of asteroseismic inclination angles

2019 ◽  
Vol 488 (1) ◽  
pp. 572-589 ◽  
Author(s):  
James S Kuszlewicz ◽  
William J Chaplin ◽  
Thomas S H North ◽  
Will M Farr ◽  
Keaton J Bell ◽  
...  
Keyword(s):  
Inclination Angle ◽  
Angle Distribution ◽  
Data Set ◽  
Single Star ◽  
Bayesian Hierarchical ◽  
Hierarchical Method ◽  
Giant Stars ◽  
Inclination Angles ◽  
Red Giant Stars ◽  
Red Giant

Abstract The stellar inclination angle – the angle between the rotation axis of a star and our line of sight – provides valuable information in many different areas, from the characterization of the geometry of exoplanetary and eclipsing binary systems to the formation and evolution of those systems. We propose a method based on asteroseismology and a Bayesian hierarchical scheme for extracting the inclination angle of a single star. This hierarchical method therefore provides a means to both accurately and robustly extract inclination angles from red giant stars. We successfully apply this technique to an artificial data set with an underlying isotropic inclination angle distribution to verify the method. We also apply this technique to 123 red giant stars observed with Kepler. We also show the need for a selection function to account for possible population-level biases, which are not present in individual star-by-star cases, in order to extend the hierarchical method towards inferring underlying population inclination angle distributions.

Effect of grout in-filling, flaw thickness and inclination angle on strength and failure pattern of rock-like specimens with single flaw

2019 ◽  
Vol 12 (22) ◽  
Author(s):  
Huilin Le ◽  
Shaorui Sun ◽  
Pinnaduwa Hewa Shanthikumar Wijayan Kulatilake ◽  
Jihong Wei
Keyword(s):  
Inclination Angle ◽  
Failure Pattern ◽  
Single Flaw

scholarly journals An experimental study on the effect of tool geometry on tool wear and surface roughness in hard turning

2020 ◽  
Vol 12 (9) ◽  
pp. 168781402095988
Author(s):  
Pham Minh Duc ◽  
Le Hieu Giang ◽  
Mai Duc Dai ◽  
Do Tien Sy
Keyword(s):  
Surface Roughness ◽  
Tool Wear ◽  
Inclination Angle ◽  
Hard Turning ◽  
Rake Angle ◽  
Machining Process ◽  
Tool Geometry ◽  
Standard Tool ◽  
Inclination Angles ◽  
Mixed Ceramic

The main purpose of this study is to investigate the influence of tool geometry (cutting edge angle, rake angle, and inclination angle) and to optimize tool wear and surface roughness in hard turning of AISI 1055 (52HRC) hardened steel by using TiN coated mixed ceramic inserts. The results show that the inclination angle is the major factor affecting the tool wear and the surface roughness in hard turning. With the increase in negative rake and inclination angles, the tool wear decreases, and the surface roughness increases. However, the surface roughness will decrease when the inclination angle increases to overpass a certain limit. This is a new and significant point in the research of the hard turning process. From this result, the large negative inclination angle (λ = −10°) should be applied to reduce the surface roughness and the tool wear simultaneously. With the optimal cutting tool angles in the research, the hard machining process is improved remarkably with decreases of surface roughness and tool wear 8.3% and 41.3%, respectively in comparison with the standard tool angles. And the proposed tool-post design approach brings an effective method to change the tool insert angles using standard tool-holders to improve hard or other difficult-to-cut materials turning quality.

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