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| 1 | Numerical simulation of gas flow process in mining-induced crack network显示文摘The exploitation of coal bed methane or coal gas is one of the most effective solutions of the problem of coal gas hazard.A better understanding of gas flow in mining-induced cracks plays an important role in comprehensive development and utilization of coal gas as well as prevention of coal gas hazard.This paper presents a case study of gas flow in mining-induced crack network regarding the situation of low permeability of coal seam.A two-dimensional physical model is constructed on the basis of geological background of mining face No.1122(1) in coal seam No.11-2,Zhangji Coal Mine,Huainan Mining Group Corporation.The mining-induced stress and cracks in overburden rocks are obtained by simulating an extraction in physical model.An evolution of mining-induced cracks in the process of advancing of coal mining face is characterized and three typical crack networks are taken from digital photos by means of image analysis.Moreover,the numerical software named COMSOL Multiphysics is employed to simulate the process of gas flow in three representative crack networks.Isograms of gas pressure at various times in mining-induced crack networks are plotted,suggesting a shape and dimension of gas accumulation area. | Zhou Hongwei Liu Jinfeng Xue Dongjie Yi Haiyang Xue Junhua | 2012 | International Journal of Mining Science and Technology2012，22，6： | 14 |
| 2 | Anti-plane Analysis of a Circular Hole withThree Unequal Cracks in One-dimensionalHexagonal Piezoelectric Quasicrystals显示文摘This paper employes variable function method and the technique of conformal mappingto discuss the anti-plane problem of a circular hole with three unequal cracksin a one-dimensional (1D) hexagonal piezoelectric quasicrystal. Based on the piezoelectricityfundamental equations of quasicrystal materials and the symmetry of1D hexagonal quasicrystal and its linear piezoelectricity effect, 1D hexagonal quasicrystalcontrol equations of anti-plane problem are derived. Applying Cauchyintegral formula, the analytical expressions for the crack tip filed intensity factorsare presented with the assumption that the crack are electrical impermeable andelectrical permeable. With the variation of the hole-size and the crack length, someof the new model of crack are obtained. In the absence of the electric load, theresults match with the classical ones. The numerical results indicate the effects ofgeometric parameters on the field intensity factors. It is verified that the horizontalcrack length and the circle radius can easily promote crack growth. Researchon such issues will provide reliable theoretical value for the engineering materialspreparation and application. | | 2016 | 工程数学学报2016，33，2： | 13 |
| 3 | Anti-plane problem of four edge cracks emanating from a square hole in piezoelectric solids显示文摘By constructing a new numerical conformal mapping and using the Stroh-type formulism, an anti-plane problem of four edge cracks emanating from a square hole in piezoelectric solids is investigated. The explicit expressions of the complex potential function, field intensity factors, energy release rates and mechanical strain energy release rate near the crack tip are obtained under the assumptions that the surfaces of the cracks and hole are electrically permeable and electrically impermeable. Numerical examples are presented to show the influences of the geometrical parameters of defects and applied mechanical/electrical loads on the energy release rate and mechanical strain energy release rate under two electrical boundary conditions. | Fan Shiwang Guo Junhong Yu Jing | 2017 | Chinese Journal of Aeronautics2017，30，1： | 9 |
| 4 | Experimental study on cracking behaviour of moulded gypsum containing two non-parallel overlapping flaws under uniaxial compression显示文摘Failure of rock mass that is subjected to compressive loads occurs from initiation, propagation, and linkage of new cracks from preexisting fissures. Our research investigates the cracking behaviour and coalescence process in a brittle material with two non-parallel overlapping flaws using a high-speed camera. The coalescence tensile crack and tensile wing cracks were the first cracks to occur from the preexisting flaws. The initiation stresses of the primary cracks at the two tips of each flaw were simultaneous and decreased with reduced flaw inclination angle. The following types of coalescence cracks were identified between the flaws: primary tensile coalescence crack, tensile crack linkage, shear crack linkage, mixed tensile-shear crack, and indirect crack coalescence. Coalescence through tensile linkage occurred mostly at pre-peak stress. In contrast, coalescence through shear or mixed tensile-shear cracks occurred at higher stress.Overall, this study indicates that the geometry of preexisting flaws affect crack initiation and coalescence behaviour. | Lekan Olatayo Afolagboye Jianming He Sijing Wang | 2017 | Acta Mechanica Sinica2017，33，2： | 7 |
| 5 | Early diagenetic deformation structures of the Furongian ribbon rocks in Shandong Province of China——A new perspective of the genesis of limestone conglomerates显示文摘Ribbon rocks are characterized by an alternation of millimeter-to centimeter-thick limestone and argillaceous deposits (marlstone or shale).The sedimentary processes and diagenetic characteristics of ribbon rocks might be critical to the formation of limestone conglomerates.According to detailed field measurement and laboratory analyses (thin section observation and XRD analysis),four types of ribbon rocks are classified,i.e.,limestone and marlstone couplet (L-M),limestone and shale couplet (L-S),thin-bedded lime mudstone (Ltb),and laminated limestone and marlstone couplet (Cl).These ribbon rocks were mostly deposited in low-energy subtidal environments (below fair-weather wave base).Ribbon rocks exhibit various subtle deformation structures such as intrastratal cracks and 'boudin' structures.Differential cementation of carbonate and argillaceous layers during early diagenesis is a prerequisite condition for the deformation of ribbon rock under compaction.Ribbon rocks would be deformed into limestone conglomerates under differential compaction that might be triggered by external forces such as storm and earthquake. | CHEN JiTao HAN ZuoZhen ZHANG XiaoLei FAN AiPing YANG RenChao | 2010 | Science China Earth Sciences2010，53，2： | 6 |
| 6 | DYNAMIC BEHAVIOR OF A CRACKED FLEXIBLE ROTOR SUPPORTED ON JOURNAL BEARINGS显示文摘The dynamic behavior of a cracked flexible rotor supported on three kinds ofjournal bearings is presented. Numerical experiments show that nonsynchronous responseswill happen due to the rotor crack, and the amplitudes of the nonsynchronous componentsbecome larger with the increase of crack. On the other hand, the fluid forces of journalbearings can suppress the nonsynchronous response. The (1/2) × or (3/2) × harmoniccomponent rarely appears for small crack near the rotating speed ratio Ω = 2Ωc or Ω =(2/3)Ωc. In the case of supercritical rotating speed, the additional 0× harmonic component is increased as the crack increases. The bearing parameters affect greatly the occur-rence of the nonsynchronous responses by means of exerting innuence on the critical spedand the stabi1ity of the system. | Zheng Jibing Meng Guang(Institute of Vibratian Engineering, Northwestern PolytechnicalUniversity, Xi’an, China, 710072) | 1997 | Chinese Journal of Aeronautics1997，10，1： | 6 |
| 7 | Nondestructive testing for crack of tunnel lining using GPR显示文摘Lining craze, as a common engineering damage, affects the bearing capacity and the safety of tunnels.To improve the capabilities of the surface crack detection in the tunnel lining, ground penetrating radar(GPR) was employed. The principle and method of GPR for cracks investigation of tunnel lining were expounded. As an application example, some field measurements in order to detect the depth of cracks for the tunnel lining were achieved in a new tunnel. All GPR investigations were made with the antennae of 1 GHz. The cracks of concrete structure were located, and the distributing and depth of cracks are inspected and estimated by GPR. The results of investigation show GPR is accurate and efficient to detect cracks of tunnel lining. | LIU Dun-wen DENG Yu YANG Fei XU Guo-yuan | 2005 | Journal of Central South University of Technology2005，12，z1： | 5 |
| 8 | INVESTIGATIONS ON THE FORMATION OF INITIAL CRACKS IN THERMAL BARRIER COATINGS PREPARED BY EB-PVD显示文摘INVESTIGATIONSONTHEFORMATIONOFINITIALCRACKSINTHERMALBARRIERCOATINGSPREPAREDBYEB-PVDS.K.Gong;L.Deng;F.S.LiuandH.B.Xu(Departmen... | S.K.Gong L. Deng F.S.Liu and H.B.Xu(Department of Material Science and Engineering,Beijing University of Aeronautics and Astronautics,Beijing 100083,China ) | 1996 | Acta Metallurgica Sinica(English Letters)1996，9，6： | 4 |
| 9 | Development of Microbe Cementitious Material in China显示文摘Microbe cementitious material as a binder has been developed due to the ever increasing awareness of environmental protection.The new cementitious material relies on microbiologically induced precipitation of calcium carbonate to bind loose particles or repair surface defects and cracks of cement-based material.This paper elaborates the research on loose sand particles cemented by microbe cement from three aspects:compressive strength,pore structure and microstructure.In addition,the research on restoration surface defects and cracks of cement-based material by microbe cement is introduced from two parameters:surface water absorption and compressive strength recover coefficient.The results show that microbe cementitious material can bind loose particles and repair surface defects or cracks of cement-based material. | 荣辉 钱春香 | 2012 | Journal of Shanghai Jiaotong university(Science)2012，17，3： | 3 |
| 10 | Reliability analysis of ship structure system with multi-defects显示文摘This paper analyzes the influence of multi-defects including the initial distortions,welding residual stresses,cracks and local dents on the ultimate strength of the plate element,and has worked out expressions of reliability calculation and sensitivity analysis of the plate element.Reliability analysis is made for the system with multi-defects plate elements.Failure mechanism,failure paths and the calculating approach to global reliability index are also worked out.After plate elements with multi-defects fail,the formula of reverse node forces which affect the residual structure is deduced,so are the sensitivity expressions of the system reliability index.This ensures calculating accuracy and rationality for reliability analysis,and makes it convenient to find weakness plate elements which affect the reliability of the structure system.Finally,for the validity of the approach proposed,we take the numerical example of a ship cabin to compare and contrast the reliability and the sensitivity analysis of the structure system with multi-defects with those of the structure system with no defects.The approach has implications for the structure design,rational maintenance and renewing strategy. | AN Hai 1,AN WeiGang 1 & ZHAO WeiTao 2 1 School of Aerospace and Civil Engineering,Harbin Engineering University,Harbin 150001,China 2 School of Aeronautics and Astronautics,Shenyang Institute of Aeronautical Engineering,Shenyang 110034,China | 2010 | Science China(Physics,Mechanics & Astronomy)2010，53，11： | 3 |
| 11 | Thermophysical properties of solution precursor plasma-sprayed La2Ce2O7 thermal barrier coatings显示文摘La2Ce2O7 (LCO) is a promising candidate for thermal barrier coatings (TBCs) due to that it provides better thermal insulation than yttria-stabilized zirconia (YSZ) does. In this work, a TBC LCO was produced by solution precursor plasma spraying (SPPS). After the solution precursors were prepared and the spraying parameters were optimized, the thermophysical properties and thermal shock performance of the coatings were tested. It was found that the SPPS coating with segmentation crack density of 6 mm^-1 had the porosities of about 33.5% at spray distances of 35 mm. The thermal conductivity of the SPPS coatings is 0.50-0.75 W·m^-1·K^-1, much lower than that of the atmospheric plasma spraying (APS) coatings (0.85-1.25 W·m^-1·K^-1). The thermal shock performance of the SPPS coatings reached 60 cycles, much better than the APS coatings. This improvement is due to the segmentation cracks in the coatings, which can improve strain tolerance and effectively relieve internal stress. This study provides reference significance for further research on thermal barrier coatings. | Bei-Bei Feng Yi Wang Qiang Jia Wei Huang Hong-Li Suo Wen Ma | 2019 | Rare Metals2019，38，7： | 3 |
| 12 | GENERALIZED 2D PROBLEM OF PIEZOELECTRIC MEDIA CONTAINING COLLINEAR CRACKS显示文摘The generalized 2D problem in piezoelectric media with collinearcracks is addressed based on Stroh’s formulation and the exact electric boundaryconditions on the crack faces.Exact solutions are obtained,respectively,for twospecial cases:one is that a piezoelectric solid with N collinear cracks is subjected touniform loads at infinity,and the other is that a piezoelectric solid containing a singlecrack is subjected to a line load at an arbitrary point.It is shown when uniform loadsare applied at infinity or on the crack faces that,the stress intensity factors are thesame as those of isotropic materials,while the intensity factor of electric displacementis dependent on the material constants and the applied mechanical loads,but not onthe applied electric loads.Moreover,it is found that the electric field inside anycrack is not equal to zero,which is related to the material properties and appliedmechanical-electric loads. | 高存法 王敏中 | 1999 | Acta Mechanica Sinica1999，15，3： | 3 |
| 13 | Problems of antiplane strain of electrically permeable cracks between bonded dissimilar piezoelectric materials显示文摘The electrically permeable slit crack within a piezoelectric body is treated as a bonded interface in electrostatics. The electric boundary conditions along the interface should be the continuity of the tangent component of the electric field strength and the normal component of the electric displacement. Using such boundary conditions, the problems of antiplane strain of collinear cracks between bonded dissimilar piezoelectric materials are exactly analyzed. Solutions of the complex potentials in a closed form are given for a single and two interface cracks. It is shown from the solutions that the stress, strain, electric field strength and electric displacement have (1/2) type of singularity at the crack tip, and the energy release rate for crack propagation depends only on both stress intensity factor and strain intensity factor. | Hou Mishan Mei Fuliang | 1998 | Chinese Science Bulletin1998，43，4： | 3 |
| 14 | Non-parallel double-crack propagation in rock-like materials under uniaxial compression显示文摘Coalescence among fractures would have influence on the stability of rock masses. Deep understanding of mechanical behavior of fractured rock masses is an important mean to identify failure mechanism of geological disaster. In this study, crack propagation processing was studied through loading pre-fractured specimens of concrete block, termed as rock-like material, in uniaxial compression tests. New non-parallel double-crack geometry was introduced to observe crack coalescence. The flaw combinations are different from the normally used flaw configurations. In addition, ultrasonic detection tests were performed on the test blocks. The stress and strain data of these tests and characteristic parameters of sound wave were recorded. The stress-strain curves of each test block under the uniaxial compression test were drawn, relations among deformation characteristics and crack angle of the crack specimens, and their overall strength were analyzed. It is found that strength of the specimen decreases as crack inclination increases under two crack inclinations. The highest uniaxial compressive strength is found in the specimen with the cracks at the same angle in different directions. Based on description of the crack initiation location, crack surface and the ultimate failure patterns, failure modes of eight subtype for test blocks are divided into three categories. It is expected that the study results could be beneficial for engineering application of jointed rock masses. | Weidong Pan Xin Wang Qiming Liu Yongkang Yuan Baodong Zuo | 2019 | International Journal of Coal Science & Technology2019，6，3： | 2 |
| 15 | Fatigue crack growth investigation on offshore pipelines with three-dimensional interacting cracks显示文摘Due to high cost of full-scale experimental setup, this study presents a numerical model on fatigue behaviours of offshore pipeline with multiple coplanar cracks under cyclic tensile loadings. The validation on numerical results is made by other researchers' experimental results, and significant parameters affecting fatigue crack growth are studied. | Yanmei Zhang Zhongmin Xiao Jun Luo | 2018 | Geoscience Frontiers2018，9，6： | 2 |
| 16 | Effect of calcium lactate on compressive strength and self-healing of cracks in microbial concrete显示文摘This paper presents the effect on compressive strength and self-healing capability of bacterial concrete with the addition of calcium lactate.Compared to normal concrete,bacterial concrete possesses higher durability and engineering concrete properties.The production of calcium carbonate in bacterial concrete is limited to the calcium content in cement.Hence calcium lactate is externally added to be an additional source of calcium in the concrete.The influence of this addition on compressive strength,self-healing capability of cracks is highlighted in this study.The bacterium used in the study is bacillus subtilis and was added to both spore powder form and culture form to the concrete.Bacillus subtilis spore powder of 2 million cfu/g concentration with 0.5%cement was mixed to concrete.Calcium lactates with concentrations of 0.5%,1.0%,1.5%,2.0%,and 2.5%of cement,was added to the concrete mixes to test the effect on properties of concrete.In other samples,cultured bacillus subtilis with a concentration of 1×10^cells/mL was mixed with concrete,to study the effect of bacteria in the cultured form on the properties of concrete.Cubes of 100 mm×100 mm×100 mm were used for the study.These cubes were tested after a curing period of 7,14,and 28 d.A maximum of 12%increase in compressive strength was observed with the addition of 0.5%of calcium lactate in concrete.Scanning electron microscope and energy dispersive X-ray spectroscopy examination showed the formation of ettringite in pores;calcium silicate hydrates and calcite which made the concrete denser.A statistical technique was applied to analyze the experimental data of the compressive strengths of cementations materials.Response surface methodology was adopted for optimizing the experimental data.The regression equation was yielded by the application of response surface methodology relating response variables to input parameters.This method aids in predicting the experimental results accurately with an acceptable range of error.Findings of this investigation indicated the influence of added calcium lactate in bio-concrete which is quite impressive for improving the compressive strength and self-healing properties of concrete. | Kunamineni VIJAY Meena MURMU | 2019 | Frontiers of Structural and Civil Engineering2019，13，3： | 2 |
| 17 | What is the role of tensile cracks in cohesive slopes?显示文摘The traditional limit equilibrium method(LEM) is often used to search for the failure surface with a minimum safety factor of slope. In this method, the failure surface is considered as a shear surface,irrespective of its form. However, tensile cracks are frequently found at the outcrops of landslides. In this study, three sets of tests on small-scale landslides with different inclination angles were conducted. The test results demonstrated that tensile cracks could arise in the slope sliding process and the failure surface is composed of both a shear and a tensile fracture surface. Based on the test results, we used the improved LEM, and replaced the traditional shear failure surface by a tensile-shear coupling one, thus new tensile failure modes for slope stability analysis can be established. The safety factors of slope in different failure modes were compared, which show that when considering soil tensile failure and tensile strength less than a certain value(e.g. 15 kPa, 44 kPa and 55 kPa for linear, circular and logarithmic spiral failure surfaces, respectively), the safety factors of slope with three different failure surfaces are less than the one that did not consider the tensile failure. The most critical failure surfaces of the slope may be composed of shear and tensile damages because the tensile strength of the soil cannot be generally greater than its cohesion. | Liansheng Tang Zhanlun Zhao Zhengui Luo Yinlei Sun | 2019 | Journal of Rock Mechanics and Geotechnical Engineering2019，11，2： | 2 |
| 18 | Damage and failure characteristics of rock similar materials with pre-existing cracks显示文摘In order to further study the damage and failure mechanism for rock similar materials,this study investigated the mechanical properties and failure characteristics,law of damage space development,and damage evolution characteristics for rock similar materials with pre-existing cracks of varying length under uniaxial compression load.The equipment used in this study is the self-developed YYW-Ⅱ strain controlled unconfined compression apparatus and the PCIE-8 acoustic emission monitoring system.Results show that,as the length of pre-existing crack increases:(1) the peak and residual strength reduces,and the peak axial strain and the strain during the initial compression phase increases;(2) the major failure mode is changed from shear failure to tensile failure along a vertical plane that passes the middle of the pre-existing crack;(3) The damage increases during the stable and accelerated development stage,and the effect of the pre-existing cracks is more during the accelerated development stage than the stable development stage. | Xiaoyu Cheng | 2019 | International Journal of Coal Science & Technology2019，6，4： | 2 |
| 19 | Enhancing strength and ductility of AlSi10Mg fabricated by selective laser melting by TiB_(2)nanoparticles显示文摘In the metallic components fabricated by the emerging selective laser melting(SLM)technology,most strategies used for strengthening the materials sacrifice the ductility,leading to the so-called strengthductility trade-off.In the present study,we report that the strength and ductility of materials can be enhanced simultaneously by introducing nanoparticles,which can break the trade-off of the metallic materials.In the case of in-situ nano-TiB_(2)decorated AlSi10Mg composites,the introduced nanoparticles lead to columnar-to-equiaxed transition,grain refinement and texture elimination.With increasing content of nanoparticles,the strength increases continually.Significantly,the ductility first increases and then decreases.Our results show that the ductility is controlled by the competition between the crack-induced catastrophic fracture and ductile fracture associated with dislocation activities.The first increase of ductility is mainly attributed to the suppression of crack-induced catastrophic fracture when TiB_(2)nanoparticles present.With the further increase of TiB_(2)nanoparticles,the subsequent decrease of ductility is mainly controlled by dislocation activities.Thus,the materials will exhibit the optimum strength and ductility combination in a certain range of TiB_(2)nanoparticles.This study clarifies the physical mechanism controlling ductility for nano-TiB_(2)decorated Al Si10Mg composites,which provides the insights for the design of structural materials. | Y.K.Xiao H.Chen Z.Y.Bian T.T.Sun H.Ding Q.Yang Y.Wu Q.Lian Z.Chen H.W.Wang | 2022 | Journal of Materials Science & Technology2022，，14： | 2 |
| 20 | Temperature and Stress Analysis of An Experimental Model of Prestressed Lightweight Concrete Platform显示文摘 | 宋玉普 宋小软 封盛 | 2000 | China Ocean Engineering2000，15，3： | 2 |
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