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| 1 | Numerical simulation of mechanisms of deformation,failure and energy dissipation in porous rock media subjected to wave stresses显示文摘The pore characteristics,mineral compositions,physical and mechanical properties of the subarkose sandstones were acquired by means of CT scan,X-ray diffraction and physical tests.A few physical models possessing the same pore characteristics and matrix properties but different porosities compared to the natural sandstones were developed.The 3D finite element models of the rock media with varied porosities were established based on the CT image processing of the physical models and the MIMICS software platform.The failure processes of the porous rock media loaded by the split Hopkinson pressure bar(SHPB) were simulated by satisfying the elastic wave propagation theory.The dynamic responses,stress transition,deformation and failure mechanisms of the porous rock media subjected to the wave stresses were analyzed.It is shown that an explicit and quantitative analysis of the stress,strain and deformation and failure mechanisms of porous rocks under the wave stresses can be achieved by using the developed 3D finite element models.With applied wave stresses of certain amplitude and velocity,no evident pore deformation was observed for the rock media with a porosity less than 15%.The deformation is dominantly the combination of microplasticity(shear strain),cracking(tensile strain) of matrix and coalescence of the cracked regions around pores.Shear stresses lead to microplasticity,while tensile stresses result in cracking of the matrix.Cracking and coalescence of the matrix elements in the neighborhood of pores resulted from the high transverse tensile stress or tensile strain which exceeded the threshold values.The simulation results of stress wave propagation,deformation and failure mechanisms and energy dissipation in porous rock media were in good agreement with the physical tests.The present study provides a reference for analyzing the intrinsic mechanisms of the complex dynamic response,stress transit mode,deformation and failure mechanisms and the disaster mechanisms of rock media. | JU Yang1,2,WANG HuiJie1,YANG YongMing1,HU QinAng3 & PENG RuiDong1 1 State Key Laboratory of Coal Resources and Safe Mining,Beijing Key Laboratory of Fracture and Damage Mechanics of Rock and Concrete,China University of Mining and Technology,Beijing 100083,China 2 Department of Mechanical and Manufacturing Engineering,University of Calgary,Calgary,Alberta,T2N 1N4,Canada 3 School of Environment and Civil Engineering,College of Engineering,Oklahoma State University,Stillwater,OK 74078,USA | 2010 | Science China(Technological Sciences)2010，53，4： | 32 |
| 2 | Energy analysis for damage and catastrophic failure of rocks显示文摘The development history and current state of studies on the characteristics and mechanisms of deformation and failure of rock materials were briefly reviewed from the viewpoint of energy.The main scope and the achievable objectives of the energy-based research system were expatiated.It was validated by experiments that the damage process of rocks can be well described by the rock damage evolution equation established based on energy dissipation.It was found from the uniaxial compression and biaxial compression tests that only a small proportion of the total input energy in hard rocks is dissipated before peak load and a large proportion in soft rocks is dissipated before peak load.For both hard and soft rocks,the energy dissipated after peak load accounts for a greater proportion.More energy would be required for rock failure under equal biaxial compression than under unequal biaxial compression.The total absorbed energy is different for rock failure under high-rate loading and low-rate loading.More fragmented failure pattern usually corresponds to higher energy absorption.The mesoscopic analysis on the damage and failure of bedded salt rocks showed that the energy dissipation is prominent and the total absorbed energy for rock failure is low when cracks propagate in the weak mud interlayer while it is contrary when cracks propagate in the salt rock.The energy accumulation,transfer,dissipation and release during the failure process of tunnel with impending failure under disturbance were analyzed theoretically based on the elastoplastic mechanics theory.Furthermore,the spatial distribution of energy dissipation and energy release of fractured rocks under unloading was simulated numerically.It was demonstrated that energy is likely to be released from the weakest surface under compression,which triggers the global failure of rocks. | XIE HePing 1,2,LI LiYun 2,1,JU Yang 2,PENG RuiDong 2 & YANG YongMing 2 1 Sichuan University,Chengdu 610065,China 2 State Key Laboratory of Coal Resources and Safe Mining,Beijing Key Laboratory of Fracture and Damage Mechanics of Rock and Concrete,China University of Mining and Technology,Beijing 100083,China | 2011 | Science China(Technological Sciences)2011，54，S1： | 29 |
| 3 | 对骨折内固定术后早期感染者保留内固定物的策略显示文摘背景:开放复位内固定术后,在内固定物存在的情况下治疗伤口深部感染极为棘手,关于治疗方案的使用,文献报道甚少。本研究旨在探讨骨折内固定术后6周内发生感染后保留内固定物直至骨性愈合的可能性。方法:通过回顾3个I级创伤中心以往的病历和创伤登记表,共纳入121例新鲜骨折患者,这些患者术中细菌培养均为阳性,内固定术后6周内共123处创口发生感染。统计保留内固定物并获骨折愈合者的比率,评价预测其治疗成败的指标。结果:86例患者(87处骨折;71%)经手术清创、保留内固定物和敏感抗生素治疗获得骨折愈合。治疗失败的有关因素包括开放性骨折(p=0.03)和髓内钉固定(p=0.01)。其他非明显相关但有相关倾向的变量包括吸烟、假单胞菌感染以及累及股骨、胫骨、踝部或足部的骨折。结论:骨折内固定术后深部感染者可通过手术清创、敏感抗生素治疗及保留内固定物成功获得骨折愈合。这些结果可通过基于危险基因、特定菌种和有关的内固定种类对患者进行选择而获得改善。 | Marschall Berkes, MD William T. Obremskey, MD MPH, Brian Scannell, MD J. Kent Ellington, MD Robert A. Hymes, MD Michael Bosse, MD, and the Southeast Fracture Consortium 黄哲元(译) 丁真奇(译) | 2010 | 中华骨科杂志2010，30，9： | 21 |
| 4 | Experimental study of dynamic mechanical properties of reactive powder concrete under high-strain-rate impacts显示文摘The dynamic mechanical properties of reactive powder concrete subjected to compressive impacts with high strain rates ranging from 10 to 1.1×102 s-1 were investigated by means of SHPB (split-Hopkinson-pressure-bar) tests of the cylindrical specimens with five different steel fiber volumetric fractions.The properties of wave stress transmission,failure,strength,and energy consumption of RPC with varied fiber volumes and impact strain rates were analyzed.The influences of impact strain rates and fiber volumes on those properties were characterized as well.The general forms of the dynamic stress-strain relationships of RPC were modeled based on the experimental data.The investigations indicate that for the plain RPC the stress response is greater than the strain response,showing strong brittle performance.The RPC with a certain volume of fibers sustains higher strain rate impact and exhibits better deformability as compared with the plain RPC.With a constant fiber fraction,the peak compressive strength,corresponding peak strain and the residual strain of the fiber-reinforced RPC rise by varying amounts when the impact strain rate increases,with the residual strain demonstrating the greatest increment.Elevating the fiber content makes trivial contribution to improving the residual deformability of RPC when the impact strain rate is constant.The tests also show that the fiber content affects the peak compressive strength and the peak deformability of RPC in a different manner.With a constant impact strain rate and the fiber fraction less than 1.75%,the peak compressive strength rises with an increasing fiber volume.The peak compressive strength tends to decrease as the fiber volume exceeds 1.75%.The corresponding peak strain,however,incessantly rises with the increasing fiber volume.The total energy Edisp that RPC consumed during the period from the beginning of impacts to the time of residual strains elevates with the fiber volume increment as long as the fiber fraction is not larger than 2%.It turns to decrease if the fiber volume exceeds 2%.The added fibers make various contributions to enhancing the capability of RPC to consume energy at different loading stages.If the fiber fraction is not larger than 2%,the added fibers make more contribution to enhancing the energy consumption ability of RPC in the period before the peak strain than in the period after the peak strain.The impact strain rate,however,distinctively affects the total energy that RPC consumed and the energy consumed in the different loading periods.The higher the impact strain rate,the more the energy consumed in the stages and therefore the higher the dynamic impact toughness.The empirical relationships of the peak compressive strength,corresponding peak strain,residual strain,total consumed energy and the energy consumed in the varied periods with the impact strain rate and the fiber fraction are derived.Four generalized forms of the dynamic impact stress-strain responses of RPC are formulated by normalizing stresses and strains as the generalized coordinates and by taking account of the influences of impact strain rates and fiber volumetric fractions. | JU Yang1,2,LIU HongBin1,SHENG GuoHua1,3 & WANG HuiJie1 1 State Key Laboratory of Coal Resources and Safe Mining,Beijing Key Laboratory of Fracture and Damage Mechanics of Rocks and Concrete,China University of Mining and Technology,Beijing 100083,China 2 Department of Mechanical and Manufacturing Engineering,University of Calgary,2500 University Drive,AB T2N 1N4,Canada 3 School of Resources and Civil Engineering,Northeastern University,Shenyang 110004,China | 2010 | Science China(Technological Sciences)2010，53，9： | 8 |
| 5 | A Model of Dynamic Recrystallization in Alloys during High Strain Plastic Deformation显示文摘Recrystallized grains, less than 200 nm in diameter were observed in heavily shear zones of a high strength low alloy steel and a Ni-based alloy, and Also grain refinement, less than 3 μm in diameter was made in high purity aluminum by ECAE at ambient temperature. The experimental results showed that high strain rate and large deformation could induce dynamic recrystallization.Based on dislocation dynamics and grain orientation change enhanced by plastic deformation,a model for the recrystallization process is developed. The model is used to explain the ultra fine grains which are formed at a temperature still much lower than that for the conventional | Qiang LI and Yongbo XU(State Key Laboratory for Fatigue and Fracture of Materials, Institute of Metal Research, Chinese Academy of Sciences,Shenyang 110015, China) To whom correspondence should be addressed Present address: Analysis Cener, School of Mater | 1999 | Journal of Materials Science & Technology1999，15，5： | 7 |
| 6 | STUDY ON FATIGUE DAMAGE BELOW THE FATIGUE LIMIT AND THE COAXING EFFECTS显示文摘STUDYONFATIGUEDAMAGEBELOWTHEFATIGUELIMITANDTHECOAXINGEFFECTSWUZhixue;LUWengeandXUHao1)(FushunPetroleuminstitute,Fushun113001,... | WU Zhixue LU Wenge and XU Hao1)(Fushun Petroleum institute, Fushun 113001, China)2)(State Key Laboratory for Fatigue and Fracture of Materials, Institute of Metal Research, ChineseAcademy of Sciences, Shenyang 110015, China)3)(Institute of Mechanical En | 1996 | Acta Metallurgica Sinica(English Letters)1996，9，3： | 5 |
| 7 | COMPUTER SIMULATION OF EARLY STAGE OF DISLOCATION STRUCTURES IN A FATIGUED COPPER SINGLE CRYSTAL显示文摘The dislocation evolution wassimulated by using positiveand negative parallelstraightedgedislocationsrandomly distributing on the primary slip planes astheinitialconditions. Thevein and wallstructuresof dynamicequilibrium have been obtained. Abig dipolestructure wasfound inthesimulation. | J.H.Yang1,2) , S.X.Li1)and C.X.Ma2) 1) State Key Laboratoryfor Fatigueand Fracture of Materials,Instituteof Metal Research ,The Chinese Academy of Sciences,72 Wenhua Road,Shenyang 110015 ,China 2) Department of Materials Physics, Northeastern Universit | 1999 | Acta Metallurgica Sinica(English Letters)1999，12，4： | 2 |
| 8 | Surgical technique显示文摘 | Kamineni S Morrey BEDistal humeral fractures treated with noncustom total elbow replacement | 2005 | J Bone Joint Surg Am2005，，： | 1 |
| 9 | Results using a prognostic computed tomography scan classification 显示文摘 | Sanders R Fortin P DiPasquale T Operative treatment in 120 displaced intraarticular calcaneal fractures | 1993 | Clin Orthop Relat Res1993，，290： | 1 |
| 10 | Othopaedic trauma association committee for coding and classification显示文摘 | Fracture and dislocation compendium | 1996 | J Orthop Trauma1996，，： | 1 |
| 11 | Anatomic and functional results in 156 cases and are view of the literature 显示文摘 | Paris H Tropiano P Clouet D Fractures of the shaft of the humerus: systematic plate fixation | 2000 | Rev Chir Orthop Reparatrice Appar Mot2000，86，4： | 1 |
| 12 | A review of 144 patients显示文摘 | Beris AE Kabbani KT Xenakis TA Surgical treatment of malleolar fractures | 1997 | Clin Orthop Relat Res1997，，341： | 1 |
| 13 | Results using a prognostic computed tomography scan classification显示文摘 | Sanders R Fortin P Dipasquale T Operative treatment in 120 displaced intra-articular calcaneal fractures | 1993 | Clin Orthop Relat Res1993，，290： | 1 |
| 14 | A randomized, controlled trial 显示文摘 | Tidemark J Ponzer S Svenson O Internal fixation compaired with total hip replacement for displaced femoral neck fractures in the elderly | 2003 | J Bone Joint Surg (Br)2003，85，： | 1 |
| 15 | Report of a WHO Study Group显示文摘 | Assessment of fracture risk and its application to screening for postmenopausal osteoporosis | | 0，，： | 1 |
| 16 | Once-yearly zoledronic acid for treatment of post-menopausal osteoporosis显示文摘 | Black DM Delmas PD Eastell R Reid IR Boonen S Cauley JA Cosman F Lakatos P Leung PC Man Z Mautalen C Mesenbrink P Hu H Caminis J Tong K Rosario-Jansen T Krasnow J Hue TF Sellmeyer D Eriksen EF Cummings SR HORIZON Pivotal Fracture Trial | | 0，，： | 1 |
| 17 | Correlation between radlologieal and functional results显示文摘 | Distal radius fracture | 2006 | Unfa Uehirurg2006，109，6： | 1 |
| 18 | Report of two cases显示文摘 | Kim S Baik MW Yoo SH Stent fracture and restenosis after placement of a drug-eluting device in the vertebral artery origin and treatment with the stent-in-stent technique | 2007 | J Neurosurg2007，106，5： | 1 |
| 19 | the flow model显示文摘 | Cacas M C E Ledoux G Marsily B Modeling fracture flow with a stochastic discrete fracture network: Calibration and validation 1 | 1990 | Water Resources Research1990，26，： | 1 |
| 20 | An important problem: Retrospective analysis of 236 cases显示文摘 | Denis F Davis S Sacral Fractures | 1988 | Clin Orthop1988，227，： | 1 |
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