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On the material dependence of experimental shear fracture orientation

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Science China Earth Sciences 2015年第12期58卷 2357-2362页

作者： Enrique GOMEZ-RIVAS Albert GRIERA Department of Geology and Petroleum Geology School of Geosciences King’s College University of Aberdeen Departament de Geologia Universitat Autònoma de Barcelona

It is not uncommon to observe shear fractures in ductile rocks oriented at more than 45° with respect to the maximum compression direction. Since these orientations cannot be explained with the classic Mohr-Coulumb or Tresca yield criteria, Zheng et al.(Journal of Structural Geology, 35: 1394–1405, 2011) proposed the maximum effective moment(MEM) failure criterion. This rule suggests that shear fractures in ductile rocks form at ?55° with the maximum compression axis and that this orientation is material-independent and, therefore, universal. Zheng et al.(Science China: Earth Sciences, 57(11): 2819–2824, 2014) used data from our own experiments as supporting evidence of their failure criterion. In this contribution we discuss why shear fracture formation in ductile rocks indeed strongly depends on the mechanical properties of the deforming medium, and why experimental data should not be taken to prove the validity of the MEM criterion. The formation mechanisms and orientations of shear fractures in our experiments significantly vary depending on the material strength and degree and type of anisotropy(composite and intrinsic). We therefore demonstrate using experimental data that a universal failure angle in ductile and anisotropic rocks does not apply. Additionally, we highlight some inconsistencies of the MEM criterion.

关键词： shear fracture anisotropy fracture orientation material properties failure criteria ductile deformation

Deformation Localization and shear fracture of a Rapidly Solidified Al-Fe-V-Si Alloy at Elevated Temperature

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Journal of Materials Science & Technology 2007年第2期23卷 237-241页

作者： Yongbo XU Shenyang National Laboratory for Materials Sciences Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China

The tensile and fatigue behavior of a dispersoid strengthened, powder metallurgy Al-Fe-V-Si alloy at ambient and elevated temperatures was investigated. The results show that the strength and ductility of the alloy decrease significantly with increasing temperature and decreasing strain rate. Micro-structural examinations reveal that this change in mechanical behavior with increasing temperature is related to the mode of deformation of the alloy. Further observations show that localized shear deformation is responsible for the losses in both strength and ductility of the alloy at elevated temperature.

关键词： Al-Fe-V-Si alloy Dispersoids Localized shear deformation shear fracture Dislocations

Development of joints and shear fractures in the Kuqa depression and its implication to regional stress field switching

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Development of joints and Shear fractures in the Kuqa depres...

Stress-state dependence of dynamic strain aging:Thermal hardening and blue brittleness

中国科学院地质与地球物理研究所2004学术年会

作者： ZHANG Zhongpei & WANG Qingchen Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China Correspondence should be addressed to Zhang Zhongpei(email:zhzhp@***)

The superimposed basin must have undergone the changes of regional stress field. Study on the nature and switch of regional stress field of superimposed basin is very useful to understanding its stress state and tectonic events during its formation and *** sensitive markers of small stress changes,joint and shear fracture,characterized by consistency of orientation over wide area,can be used to reconstruct paleostress state and its *** observations and analysis on the orientations,geometrical patterns,sequences of joints and shear fractures and their chronological relation to faults and folds show that,the NEE-SWW systematic joints and NNW-SSE systematic joints developed in the Mesozoic and Cenozoic strata are much more prominent than NW-SE systematic joints and shear fractures with different *** the NWW-SEE and NW-SE systematic joints formed later than NEE-SWW systematic joints but earlier than shear fractures with different *** to the relationships between joint and shear fractures and stress,the NEE-SWW systematic joints are inferred to result from lateral weak extension caused by the late Cretaceous regional uplift,while the NNW-SSE and NW-SE systematic joints are interpreted as syn-tectonic deformation relating to strong N-S compression in the *** some conjugate shear fractures occur probably due to sinistral strike-slip faulting in the Kuqa *** the beginning of the Neogene,the stress field changed and the maximal principal stressσ switched from vertical to horizontal.

关键词： joint shear fracture paleostrcss paleostress field Kuqa depression

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International Journal of Minerals,Metallurgy and Materials 2021年第5期28卷 854-866页

作者： Wen-qi Liu Jun-he Lian Advanced Manufacturing and Materials Department of Mechanical EngineeringAalto UniversityPuumiehenkuja 302150 EspooFinland Impact and Crashworthiness Lab Department of Mechanical EngineeringMassachusetts Institute of Technology77 Massachusetts AvenueCambridgeMA 02139-4307USA

This study aims to discover the stress-state dependence of the dynamic strain aging(DSA)effect on the deformation and fracture behavior of high-strength dual-phase(DP)steel at different deformation temperatures(25-400°C)and reveal the damage mechanisms under these various *** achieve different stress states,predesigned specimens with different geometric features were *** electron microscopy was applied to analyze the fracture modes(e.g.,dimple or shear mode)and underlying damage mechanism of the investigated *** is present in this DP steel,showing the Portevin-Le Chatelier(PLC)effect with serrated flow behavior,thermal hardening,and blue brittleness *** show that the stress state contributes distinctly to the DSA effect in terms of the magnitude of thermal hardening and the pattern of blue *** low stress triaxiality or Lode angle parameter promotes DSA-induced blue ***,the damage mechanisms also show dependence on the stress states in conjunction with the DSA effect.

关键词： dynamic strain aging effect Portevin-Le Chatelier effect damage mechanism dimple fracture shear fracture dual-phase steel

Mechanical Properties,Damage and fracture Mechanisms of Bulk Metallic Glass Materials

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Journal of Materials Science & Technology 2007年第6期23卷 I0003-I0006,747-767页

作者： Zhefeng ZHANG Fufa WU Guo HE Eckert Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China School of Materials Science and Engineering Shanghai Jiaotong University Shanghai 200030 China IFW Dresden Institute for Complex Materials P.O. Box 270116 D-01171 Dresden Germany TU Dresden Institute for Materials Science D-01062 Dresden Germany

The deformation, damage, fracture, plasticity and melting phenomenon induced by shear fracture were investigated and summarized for Zr-, Cu-, Ti- and Mg-based bulk metallic glasses （BMGs） and their composites. The shear fracture angles of these BMG materials often display obvious differences under compression and tension, and follow either the Mohr-Coulomb criterion or the unified tensile fracture criterion. The compressive plasticity of the composites is always higher than the tensile plasticity, leading to a significant inconsistency. The enhanced plasticity of BMG composites containing ductile dendrites compared to monolithic glasses strongly depends on the details of the microstructure of the composites. A deformation and damage mechanism of pseudo-plasticity, related to local cracking, is proposed to explain the inconsistency of plastic deformation under tension and compression. Besides, significant melting on the shear fracture surfaces was observed. It is suggested that melting is a common phenomenon in these materials with high strength and high elastic energy, as it is typical for BMGs and their composites failing under shear fracture. The melting mechanism can be explained by a combined effect of a significant temperature rise in the shear bands and the instantaneous release of the large amount of elastic energy stored in the material.

关键词： Bulk metallic glasses (BMGs) criterion Plastic deformation Mechanical properties shear fracture Failure Melting phenomenon

Laboratory visualization of damage asymmetry formation of rock fracture via acoustic emission and digital imaging correlation

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第11期16卷 4480-4490页

作者： Qiquan Xiong Qing Lin Yue Gao Yanhui Han Jesse C.Hampton Geomechanics and Damage Group(GeoD) Department of Civil and Environmental EngineeringUniversity of Wisconsin-MadisonMadisonWI53706USA State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China College of Petroleum Engineering China University of PetroleumBeijing102249China Aramco Americas:Aramco Research Center-Houston HoustonTX77084USA

Rock fracture mechanics and accurate characterization of rock fracture are crucial for understanding a variety of phenomena interested in geological engineering and *** phenomena range from very large-scale asymmetrical fault structures to the scale of engineering projects and laboratory-scale rock fracture *** study can involve mechanical modeling,site or post-mortem investigations,and inspection on the point cloud of the source locations in the form of earthquake,microseismicity,or acoustic *** study presents a comprehensive data analysis on characterizing the forming of the asymmetrical damage zone around a laboratory mixed-mode rock *** substantiate the presence of asymmetrical damage through qualitative analysis and demonstrate that measurement uncertainties cannot solely explain the observed *** implications of this demonstration can be *** a larger scale,it solidifies a mechanical model used for explaining the contribution of aseismic mechanisms to asymmetrical fault *** a laboratory scale,it exemplifies an alternative approach to understanding the observational difference between the source location and the in situ or post-mortem inspection on the rock fracture *** mechanical model and the data analysis can be informative to the interpretations of other engineering practices as well,but may face different types of challenges.

关键词： shear fracture Dynamics of fracture Acoustic emission Digital image correlation Uncertainty analysis Error ellipsoid

Mechanical Properties of Deep-buried Marble Material Under Loading and Unloading Tests

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Journal of Wuhan University of Technology(Materials Science) 2013年第3期28卷 514-520页

作者：李新平 ZHAO Hang WANG Bin XIAO Taoli Hubei Key Laboratory of Roadway Bridge and Structure Engineering Wuhan University of Technology School of Civil Engineering and Architecture Wuhan University of Technology Changjiang Institute of Survey Planning Design and Research School of Urban Construction Yangtze University

The mechanical properties are essentially different when rock material is subjected to loading or unloading conditions. In this study, loading and unloading tests with various confining pressures are conducted to investigate the mechanical properties of marble material samples taken from the deep diversion tunnels of Jinping II Hydropower Station. The stress-strain relationship, failure characteristics and strength criterion are compared and analyzed based on the experiment results. The results show： in the loading and unloading test, peak strength, lateral strain, axial strain and plastic deformation increase significantly as the confining pressure increases. Lateral strain increased significantly and obvious lateral dilatancy can be observed to the change of confining pressure; The fracture mode is mainly the single shear fracture for the triaxial compression test and post-peak test, angle between the failure surface and the ends of the rock material becomes smaller as the confining pressure increases. Hock-Brown strength criterion reflects the strength characteristics of marble material under two different unloading conditions, and has some supplementary effects to the rock material of mechanical field.

关键词： deep-buried material loading and unloading tests mechanical properties strength criterion shear fracture

Characteristics of New-type Energy Absorber for Vehicle Collision

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Journal of Shanghai Jiaotong university(Science) 2008年第2期13卷 252-256页

作者：许庆新沈荣瀛周海亭 State Key Laboratory of Mechanical System and Vibration Shanghai Jiaotong University

A new type energy absorber was introduced,which is composed of thousands of thin ring plates with different *** it can switch the impact to thousands of shearing actions among thin ring plates inside the absorber,the impact energy is decentralized and dissipated gradually,the impact acting time is extended and the peak of acceleration is reduced *** simulations by finite element method (FEM) coupled with smoothed particle hydrodynamics (SPH) method were preformed to predict the energy absorption *** absorption ability with different impact velocities was studied and the effects of thickness and material of ring plates were *** sled crash test was carried out to validate the result of *** new type absorber is effective for collision that impact velocity is lower than 40 km/h.

关键词： energy absorber impact shear fracture numerical simulation smoothed particle hydrodynamics sled crash test

Effect of Porous Copper Pore Density on Joint Interface:Microstructure and Mechanical Analysis

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Journal of Harbin Institute of Technology(New Series) 2022年第1期29卷 24-31页

作者： Nur Amirah Mohd Zahri Farazila Yusof Yukio Miyashita Tadashi Ariga ASMdAbdul Haseeb Nazatul Liana Sukiman Department of Mechanical Engineering Faculty of EngineeringUniversity of MalayaKuala Lumpur 50603Malaysia Department of Mechanical Engineering Faculty of Engineering and Advanced Manufacturing&Material Processing(AMMP Centre)University of MalayaKuala Lumpur 50603Malaysia Department of Mechanical Engineering Nagaoka University of TechnologyNagaoka 940-2188Japan Department of Metallurgical Engineering Tokai UniversityHiratsuka 259-1292Japan Department of Mechanical Engineering Faculty of Engineering and Centre of Advanced Materials(CAM)University of MalayaKuala Lumpur 50603Malaysia

The effect of the pore density of porous copper(Cu)on brazed Cu/porous Cu was investigated.A filler with a composition of Cu⁃9.0Sn⁃7.0Ni⁃6.0P(Sn:Tin;Ni:Nickel;P:Phosphorus)and porous Cu with pore densities of 15 pores per inch(PPI),25 PPI,and 50 PPI were *** joint strength of Cu/porous Cu was evaluated with shear tests at different brazing *** of the joint interface and fractured surface were achieved with scanning electron microscope(SEM),energy dispersive X⁃ray spectroscopy(EDX),and X⁃ray diffraction(XRD).The micro⁃hardness test of Cu/porous Cu joint interface showed a high hardness value(HV)for 50 PPI porous *** result was in line with its low shear *** was proved that the joint strength of Cu/porous Cu is dependent on the pore density of the porous Cu structure and brittle phases of Cu_(3)P and Ni_(3)P in the brazed interface.

关键词： porous metal brazing interface microstructure shear fracture