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Mesomechanics coal experiment and an elastic-brittle damage model based on texture features

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International Journal of Mining Science and Technology 2018年第4期28卷 634-642页

作者： Sun Chuanmeng Cao Shugang Li Yong School of Electrical and Control Engineering North University of ChinaTaiyuan 030051China National Key Laboratory of Electronic Measurement Technology North University of ChinaTaiyuan 030051China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China College of Resources and Environmental Science Chongqi ng UniversityChongqing 400044China

To accurately describe damage within coal, digital image processing technology was used to determine texture parameters and obtain quantitative information related to coal meso-cracks. The relationship between damage and mesoscopic information for coal under compression was then analysed. The shape and distribution of damage were comprehensively considered in a defined damage variable, which was based on the texture characteristic. An elastic-brittle damage model based on the mesostructure information of coal was established. As a result, the damage model can appropriately and reliably replicate the processes of initiation, expansion, cut-through and eventual destruction of microscopic damage to coal under compression. After comparison, it was proved that the predicted overall stress-strain response of the model was comparable to the experimental result.

关键词： Mesomechanics experiment Image processing Texture feature damage variable damage model

Thermal-hydro-mechanical coupling damage model of brittle rock

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Journal of Central South University 2014年第3期21卷 1136-1141页

作者：李鹏饶秋华李卓马雯波马彬 School of Civil Engineering Central South University

Based on fluid mechanics, thermodynamics and damage mechanics, thermal-hydro-mechanical （THM） coupling damage model of brittle rock is established by analyzing THM coupling mechanism, where THM coupling damage variable DTHM is dominated by TH coupling damage variable DTH, TM coupling damage variable DTM and HM coupling damage variable DHM, and DTH is firstly expressed in term of dimensionless total thermal conductivity of the water Nu. Permeability test, uni-axial compression test and THM coupling test are conducted to measure the permeability, elastic modulus and THM coupling stress-strain curves of brittle rock. The tested values of THM coupling elastic modulus E＇HM are in good agreement with the predicted values of THM coupling elastic modulus ETHM, which can verify the newly established THM coupling damage model.

关键词： damage model THM coupling mechanism permeability test THM coupling test brittle rock

The Mechanical Characteristics and damage model of Helan Mountain Rock based on Acoustic Emission

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Journal of Wuhan University of Technology(Materials Science) 2021年第6期36卷 845-864页

作者： YANG Youzhen ZHAO Yishen MA Hailong CHEN Wenwu FENG Haiyan JIN Menghua LIN Qingqing MA Wenguo School of Physics and Electronic and Electrical Engineering Ningxia UniversityYinchuan 750021China Institute of Solid Mechanics Ningxia UniversityYinchuan 750021China College of Civil Engineering and Mechanics Lanzhou UniversityYinchuan 750021China Institute of Ethnic Preparatory Education Ningxia UniversityLanzhou 730000China Shanghai Junnel Engineering Co.Ltd. Shanghai 200030China

With the risk of disappearing for the rock paintings considering long-term exposure in Helan Mountain,the freeze-thaw(F-T)cycling experiments were carried out with 12-hour F-T cycling(0,10,20,30,and 40 F-T cycles)under five kinds of confining pressures(5,10,20,30,and 40 MPa).The acoustic emission(AE)detect technology was used to reveal the rock fracturing characteristics during the triaxial compression test whole *** stress-strain relation changes along with different confining pressures and F-T *** stress and residual stress changes along with different confining pressures and damages,and the variation of axial stress-AE ringing counts-time changes along with different confining pressures and F-T *** damage variable with AE parameter under F-T and force coupling was defined for the first time,and the damages model was *** experimental results show that the F-T cycles lead to the decrease of rock strength and the gradual transformation of compression failure mode from brittleness to *** confining pressure provides a certain ability to resist deformation and inhibit crack growth for rock samples after F-T *** temporal and spatial evolution law of AE counts well corresponds to the loading and failure process of the rock *** AE 3D positioning technology can accurately capture the development position and direction of internal cracks and pores of rock,and the failure form is conical shear *** established damage model has a better fittingness between the theoretical calculation results and the test results,and is reasonable to be used in the future for protection of Helan Mountain rock painting.

关键词： helan mountain rock freeze-thaw(F-T) acoustic emission(AE) damage model

A NEW damage model FOR MICROCRACK-WEAKENED BRITTLE SOLIDS

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Acta Mechanica Sinica 1993年第3期9卷 251-260页

作者：冯西桥余寿文 Department of Engineering Mechanics Tsinghua University Beijing China 100084

In the present paper, a micromechanically based damage model for microcrack-weakened solids is developed. The concept of the domain of microcrack growth (DMG) is defined and used to describe the damage state and the anisotropic properties of brittle materials. After choosing an appropriate fracture criterion of microcrack, we obtain the analytical expression of DMG under a monotonically in- creasing proportional plane stress. Under a complex loading path, the evolution equation of DMG and the overall effective compliance tensor of damaged materials are given.

关键词： damage model brittle material constitutive relation

A damage model of Concrete under Freeze-Thaw Cycles

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Journal of Wuhan University of Technology(Materials Science) 2003年第3期18卷 40-42页

作者：卫军 School of Civil Engineering & Mechanics Huazhong University of Science and Technology

The frost durability of concrete is considered from structural engineering points of *** failure process is analyzed and a damage model is established,which can describe the deterioration of concrete during the whole freeze thawing *** model is verified by test *** parameters of model can explain the effect of pore structures or water to binder ratio on frost durability of concrete.

关键词： concrete frost durability damage model parameters of model

Online damage model of Steam Turbine based on Continuum damage Mechanics 36

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Online Damage Model of Steam Turbine based on Continuum Dama...

Study on sulfur deposition damage model of fractured gas reservoirs with high-content H_(2)S

第36届中国控制会议

作者： Yongjian Sun Shizeng Lu Qingjin Meng Xiaohong Wang School of Electrical Engineering University of Jinan

ISBN: (纸本)9781538629185

Due to the drawbacks of linear damage accumulation model,it is necessary to substitute nonlinear model for it.A novel concept of online damage calculation model based on the continuum damage mechanics is proposed in this *** transfer process is analyzed detailedly,the complexity is decomposed into single input and single output *** of thermal decomposition with continuum damage mechanics establish the foundation for online damage computing model.A set of numerical finite element analysis is utilized to verify the effectiveness of this ***,simulation implemented in Simulink software is given out to supply a new practical exploration in engineering.

关键词： low cycle fatigue fatigue damage steam turbine damage model continuum damage mechanics

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Petroleum 2017年第3期3卷 321-325页

作者： Linji He Xiao Guo State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengduSichuan 610500China

Due to extreme poison,strong corrosion,and complex precipitation and deposition of H_(2)S in the reservoir,it is very difficult and risky to investigate and explore drilling,completion,production and gas *** the course of production of fractured gas reservoir with high H_(2)S content,formation pressure falls continually,which lead to decline of solubility of sulfur particles in gas *** particles which dissolve in gas phase originally in the formation should precipitate from gas phase after running up to saturation state and deposit at pore space and throat,sequentially resulting in formation porosity and permeability *** present,the researches of sulfur deposition are mainly focused on the conventional gas reservoirs and sulfur deposition in the near wellbore region is generally estimated using Roberts'***,most of the gas reservoirs with high-content H2S are fractured gas reservoirs,classical damage model is no longer applicable to fractured gas reservoirs with high H2S *** the present study,a sulfur deposition damage model is *** refined model,based on non-Darcy flow,takes into consideration the effects of sulfur deposition,variation in gas properties and *** addition,the effect of gas well production rate on formation permeability is also *** results show that formation permeability decreases with fracture aperture and gas well production rate *** bigger gas well production rate is,the quicker sulfur *** sulfur deposition of fractured gas reservoir with high-content H_(2)S is mainly in the near wellbore zone,and the fracture aperture has a significant impact on the formation permeability in the near wellbore zone.

关键词： High-content H_(2)S Fracture Sulfur deposition Permeability damage model

SIMULATION OF MULTIPLE-STEP LOADING TRIAXIAL COMPRESSION TEST ON A MUDSTONE BY A NEW damage model Paper No.294

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SIMULATION OF MULTIPLE-STEP LOADING TRIAXIAL COMPRESSION TES...

Extension of Flow Behaviour and damage models for Cast Iron Alloys with Strain Rate Effect

ISRM-Sponsored International Symposium on Rock Mechanics:"Rock Characterisation,modelling and Engineering Design Methods"(SINOROCK2009)

作者： A.Taheri K.Tani Tokyo University of Science Yokohama National University

ISBN: (纸本)9789628014170

Multiple-step Loading Triaxial Compression Test（ML-TCT）,permits determination of a failure envelope by testing a single rock specimen in a series of consolidation and shearing *** appropriate rocks,this technique allows determination of strength parameters from fewer specimens than does conventional triaxial testing,which requires three or more specimens to determine a failure ***,because of accumulated damage in the specimen with repeated cycles of axial loading/unloading,the shear strength is prone to be underestimated. Therefore,a Multiple-step Loading damage（MLD） model was proposed to simulate ML-TCTs with various stress *** the MLD model,the damage accumulated in the specimen by the repeated cycles of axial loading/unloading is represented by the plastic axial strains. Two series of ML-TCTs were carried out on a sedimentary soft rock of *** the first series repeated steps of axial loading-unloading were made under the constant effective confining pressures,σ'= 0.4,0.6,1.0,1.2,1.6,2.0 MPa,to determine all geotechnical parameters to describe the MLD *** the second series,repeated cycles of axial loading-unloading were made under different effective confining pressures to verify the MLD *** kinds of stress paths were attempted,three tests were done in increasing effective confining pressures in a stepwise manner and two tests were done in decreasing fashion. The MLD model built to simulate ML-TCTs on the mudstone with various stress *** model is comprised of five relationships,and is prepared on the basis of the results obtained from the first series of *** model allows prediction of peak deviator stress and the relevant excess pore water pressure due to previous plastic deformations in the specimen for mudstone. The verification of the MLD model was made using two *** the first one,comparisons were made between the experimental results of ML-TCTs and the calculated results of ML-TCTs with the id

关键词： Multiple-step loading triaxial compression test Mudstone damage model

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 297-310页

作者： Chuang Liu Dongzhi Sun Xianfeng Zhang Florence Andrieux Tobias Gersterc School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China Fraunhofer Institute for Mechanics of Materials(IWM) 79108 FreiburgGermany Fraunhofer Institute for High Speed Dynamics Ernst-Mach-Institute(EMI)79104 FreiburgGermany

Cast iron alloys with low production cost and quite good mechanical properties are widely used in the automotive *** study the mechanical behavior of a typical ductile cast iron(GJS-450)with nodular graphite,uni-axial quasi-static and dynamic tensile tests at strain rates of 10^(-4),1,10,100,and 250 s^(-1)were carried *** order to investigate the influence of stress state on the deformation and fracture parameters,specimens with various geometries were used in the *** strain curves and fracture strains of the GJS-450 alloy in the strain rate range of 10^(-4)to 250 s^(-1)were obtained.A strain rate-dependent plastic flow model was proposed to describe the mechanical behavior in the corresponding strain-rate *** available damage model was extended to take the strain rate into account and calibrated based on the analysis of local fracture *** with the proposed plastic flow model and the damage model were conducted to observe the deformation and fracture *** results show that the strain rate has obviously nonlinear effects on the yield stress and fracture strain of GJS-450 *** predictions with the proposed plastic flow and damage models at various strain rates agree well with the experimental results,which illustrates that the rate-dependent plastic flow and damage models can be used to describe the mechanical behavior of cast iron alloys at elevated strain *** proposed plastic flow and damage models can be used to describe the deformation and fracture analysis of materials with similar properties.

关键词： Dynamic behavior of materials Strain rate dependency damage model Voce model Cast iron