Objectives: This article presents a new computational procedure to discover scratches buried in the earth's crust. We also validate this new interdisciplinary analysis method with regional gravity data located in a ...Objectives: This article presents a new computational procedure to discover scratches buried in the earth's crust. We also validate this new interdisciplinary analysis method with regional gravity data located in a well-known Dabie orogenic zone for test. Methods: Based on the scratch analysis method evolved with mathematical morphology of surfaces, we present a procedure that extracts information of the crustal scratches from regional gravity data. Because the crustal scratches are positively and highly correlated to crustal deformation bands, it can be used for delineation of the crustal deformation belts. The scratches can be quantitatively characterized by calculation of the ridge coefficient function, whose high value traces delineate the deformation bands hidden in the regional gravity field. In addition, because the degree of crustal deformation is an important indicator of tectonic unit divisions, so the crust can be further divided according to the degree of crustal deformation into some tectonic units by using the ridge coefficient data, providing an objective base map for earth scientists to build tectonic models with quantitative evidence. Results: After the ridge coefficients are calculated, we can further enhance the boundary of high ridge-coefficient blocks, resulting in the so-called ridge-edge coefficient function. The high-value ridge-edge coefficients are well correlated with the edge faults of tectonic units underlay, providing accurate positioning of the base map for compilation of regional tectonic maps. In order to validate this new interdisciplinary analysis method, we select the Dabie orogenic zone as a pilot area for test, where rock outcrops are well exposed on the surface and detailed geological and geophysical surveys have been carried out. Tests show that the deformation bands and the tectonic units, which are conformed by tectonic scientists based on surface observations, are clearly displayed on the ridge and ridge-edge coefficient images obtained in this article. Moreover, these computer-generated images provide more accurate locations and geometric details. Conclusions: This work demonstrates that application of modern mathematical tools can promote the quantitative degree in research of modern geosciences, helping to open a door to develop a new branch of mathematical tectonics.展开更多
The thin foil specimen of a ferrite-austenite duplex stainless steel was tensiled under transmis- sion electron microscope(TEM).It was found that both in ferrite and austenite the local deformation band at crack tip w...The thin foil specimen of a ferrite-austenite duplex stainless steel was tensiled under transmis- sion electron microscope(TEM).It was found that both in ferrite and austenite the local deformation band at crack tip was formed near to the crack propagating direction.Its forma- tion was related with the crack tip Schmid factor,dislocation shielding,latent hardening and hardening coefficient.When the crack tip emitted dislocations to a slip system by the action of pure mode Ⅱ stress resolute,and the decreasing rate of hardening coefficient was suitable,lo- cal deformation band was easy to form.展开更多
In order to further understand the similarity and difference betweendeformation mechanisms of single crystals and poly-crystalline materials, the influence of externalconstraint and rolling geometry on the deformation...In order to further understand the similarity and difference betweendeformation mechanisms of single crystals and poly-crystalline materials, the influence of externalconstraint and rolling geometry on the deformation behaviour of copper single crystals with{123}<634> orientation was investigated by embedding them into metal frames of different strengths.The metal frames were made of aluminum and mild steel, respectively. The results show that thedeformation banding degree of the crystal increases with the strength of metal frame and shearstrain. For the crystals rolled under lower (gamma)g ((gamma)g is the ratio of the geometricalredundant shear strain to the normal rolling strain), the deformation is homogeneous. For thecrystals rolled under higher (gamma)g, the deformation is extremely inhomogeneous. The deformationis more homogeneous in the crystals rolled in steel frames than that rolled in aluminum frames. TheS-orientation is more stable in the crystals rolled under lower (gamma)g than that rolled underhigher (gamma)g.展开更多
The conductivity anisotropy behaviour is described for certain environment in the Earths crust and the MT inversion method for a layered symmetrically anisotropic model is presented. The inversion interpretations of t...The conductivity anisotropy behaviour is described for certain environment in the Earths crust and the MT inversion method for a layered symmetrically anisotropic model is presented. The inversion interpretations of the anisotropic model from the observational data are helpful to identify the earthquake precusors as indicated by the deep conductivity anisotropic variations, and also provide some useful information to investigate the stress states and deformation bands in the deep crust of the Earth.展开更多
The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitut...The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitutive theory([1]) and B-L planar anisotropy yield criterion([2]). Simulated results are compared with experimental ones. Very good consistence is obtained between numerical and experimental results. The relationship between the anisotropy coefficient R and the shear band angle theta is found.展开更多
Flow localization, which is an importantmode of deformation in engineering materi-als, has been the interesting subject ofa number of experimental observationsand theoretical investigations in recentyears. However, th...Flow localization, which is an importantmode of deformation in engineering materi-als, has been the interesting subject ofa number of experimental observationsand theoretical investigations in recentyears. However, the basic mechanism ofthe phenomena is not well understood atpresent. In a tensile test, the initiationand growth of a shear band are often simul-taneous. Therefore, it is rather difficult展开更多
For the development of high-strength Mg alloys,active use of Laves phases such as C14-type Mg_(2)Yb and Mg_(2)Ca is strongly expected.However,the brittleness of the Laves phases is the biggest obstacle to it.We first ...For the development of high-strength Mg alloys,active use of Laves phases such as C14-type Mg_(2)Yb and Mg_(2)Ca is strongly expected.However,the brittleness of the Laves phases is the biggest obstacle to it.We first found that kink-band formation can be induced in directionally solidified Mg/Mg_(2)Yb and Mg/Mg_(2)Ca eutectic lamellar alloys when a stress is applied parallel to the lamellar interface,leading to a high yield stress accompanied with ductility.That is,microstructural control can induce a new deformation mode that is not activated in the constituent phases,thereby inducing ductility.It was clarified that the geometric relationship between the operative slip plane in the constituent phases and the lamellar interface,and the microstructural features that provide kink-band nucleation sites are important factors for controlling kink-band formation.The obtained results show a possibility to open the new door for the development of novel high-strength structural material using the kink bands.展开更多
The chiral geometry of multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters γ in the particle rotor model with πh11/2×γh11/2^-1.The energy spect...The chiral geometry of multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters γ in the particle rotor model with πh11/2×γh11/2^-1.The energy spectra,electromagnetic transition probabilities B(M1) and B(E2),angular momenta,and K-distributions are studied.It is demonstrated that the chirality still remains not only in the yrast and yrare bands,but also in the two higher excited bands whenγ deviates from 30°.The chiral geometry relies significantly on γ,and the chiral geometry of the two higher excited partner bands is not as good as that of the yrast and yrare doublet bands.展开更多
Multiple ballistic impacts are carried out on a 2024-T4 aluminum alloy by spherical steel projectiles(5-mm diameter)at~400 m s^(-1),to investigate its dynamic deformation and damage.The ballistic impact process is cap...Multiple ballistic impacts are carried out on a 2024-T4 aluminum alloy by spherical steel projectiles(5-mm diameter)at~400 m s^(-1),to investigate its dynamic deformation and damage.The ballistic impact process is captured with high-speed photography.Postmortem samples are characterized with optical imaging,three-dimensional laser scanning,microhardness testing and electron backscatter diffraction.With increasing number of impacts,crater diameter increases slightly,but crater depth and crater volume increase significantly,and strain accumulation leads to microhardness increase overall.Crater parameters all follow power-law relations with the number of impacts.Twin-like deformation bands and macroscopic deformation twins are produced by impact as a result of spontaneous dislocation self-pinning under high strain rate,large shear deformation.Under multiple impacts,shear strain accumulation in the arc-shaped region of the crater induces deformation twinning when it exceeds a critical value(~1.1-1.6).It is highly possible that the deformation twins are related to deformation bands,since they both share one set of the{111}pole with the initial matrix grain.A finite element method model is optimized to reproduce experimental observations and interpret deformation mechanisms.展开更多
The evolution of shear bands in the glassy matrix composites was observed and analyzed during in-situ tension.Based on the simple calculation,the temperature rise within the shear bands is sufficient to cause the form...The evolution of shear bands in the glassy matrix composites was observed and analyzed during in-situ tension.Based on the simple calculation,the temperature rise within the shear bands is sufficient to cause the formation of viscous shearing layer,resulting in the early failure.Zr-based metallic-glass-matrix composites(labeled as DH1 and DH2) exhibit improved tensile ductility rather than brittle failure,since the existence of secondary ductile dendrites promotes the impedance of prompt propagation of shear bands,evidenced by the multiplication of shear bands.展开更多
基金National Science Foundation and Chinese Geological Survey for supporting this work
文摘Objectives: This article presents a new computational procedure to discover scratches buried in the earth's crust. We also validate this new interdisciplinary analysis method with regional gravity data located in a well-known Dabie orogenic zone for test. Methods: Based on the scratch analysis method evolved with mathematical morphology of surfaces, we present a procedure that extracts information of the crustal scratches from regional gravity data. Because the crustal scratches are positively and highly correlated to crustal deformation bands, it can be used for delineation of the crustal deformation belts. The scratches can be quantitatively characterized by calculation of the ridge coefficient function, whose high value traces delineate the deformation bands hidden in the regional gravity field. In addition, because the degree of crustal deformation is an important indicator of tectonic unit divisions, so the crust can be further divided according to the degree of crustal deformation into some tectonic units by using the ridge coefficient data, providing an objective base map for earth scientists to build tectonic models with quantitative evidence. Results: After the ridge coefficients are calculated, we can further enhance the boundary of high ridge-coefficient blocks, resulting in the so-called ridge-edge coefficient function. The high-value ridge-edge coefficients are well correlated with the edge faults of tectonic units underlay, providing accurate positioning of the base map for compilation of regional tectonic maps. In order to validate this new interdisciplinary analysis method, we select the Dabie orogenic zone as a pilot area for test, where rock outcrops are well exposed on the surface and detailed geological and geophysical surveys have been carried out. Tests show that the deformation bands and the tectonic units, which are conformed by tectonic scientists based on surface observations, are clearly displayed on the ridge and ridge-edge coefficient images obtained in this article. Moreover, these computer-generated images provide more accurate locations and geometric details. Conclusions: This work demonstrates that application of modern mathematical tools can promote the quantitative degree in research of modern geosciences, helping to open a door to develop a new branch of mathematical tectonics.
文摘The thin foil specimen of a ferrite-austenite duplex stainless steel was tensiled under transmis- sion electron microscope(TEM).It was found that both in ferrite and austenite the local deformation band at crack tip was formed near to the crack propagating direction.Its forma- tion was related with the crack tip Schmid factor,dislocation shielding,latent hardening and hardening coefficient.When the crack tip emitted dislocations to a slip system by the action of pure mode Ⅱ stress resolute,and the decreasing rate of hardening coefficient was suitable,lo- cal deformation band was easy to form.
文摘In order to further understand the similarity and difference betweendeformation mechanisms of single crystals and poly-crystalline materials, the influence of externalconstraint and rolling geometry on the deformation behaviour of copper single crystals with{123}<634> orientation was investigated by embedding them into metal frames of different strengths.The metal frames were made of aluminum and mild steel, respectively. The results show that thedeformation banding degree of the crystal increases with the strength of metal frame and shearstrain. For the crystals rolled under lower (gamma)g ((gamma)g is the ratio of the geometricalredundant shear strain to the normal rolling strain), the deformation is homogeneous. For thecrystals rolled under higher (gamma)g, the deformation is extremely inhomogeneous. The deformationis more homogeneous in the crystals rolled in steel frames than that rolled in aluminum frames. TheS-orientation is more stable in the crystals rolled under lower (gamma)g than that rolled underhigher (gamma)g.
文摘The conductivity anisotropy behaviour is described for certain environment in the Earths crust and the MT inversion method for a layered symmetrically anisotropic model is presented. The inversion interpretations of the anisotropic model from the observational data are helpful to identify the earthquake precusors as indicated by the deep conductivity anisotropic variations, and also provide some useful information to investigate the stress states and deformation bands in the deep crust of the Earth.
基金The project supported by the National Natural Science Foundation of China and the Excellent Youth Teacher Foundation of the State Education Commission of China
文摘The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitutive theory([1]) and B-L planar anisotropy yield criterion([2]). Simulated results are compared with experimental ones. Very good consistence is obtained between numerical and experimental results. The relationship between the anisotropy coefficient R and the shear band angle theta is found.
文摘Flow localization, which is an importantmode of deformation in engineering materi-als, has been the interesting subject ofa number of experimental observationsand theoretical investigations in recentyears. However, the basic mechanism ofthe phenomena is not well understood atpresent. In a tensile test, the initiationand growth of a shear band are often simul-taneous. Therefore, it is rather difficult
基金supported by Japan Society for the Promotion of Science (JSPS) KAKENHI for Scientific Research on Innovative Areas "MFS Materials Science" (Grant Numbers: JP18H05478 and JP18H05475)partly supported by the Light Metals Educational Foundation of Japan。
文摘For the development of high-strength Mg alloys,active use of Laves phases such as C14-type Mg_(2)Yb and Mg_(2)Ca is strongly expected.However,the brittleness of the Laves phases is the biggest obstacle to it.We first found that kink-band formation can be induced in directionally solidified Mg/Mg_(2)Yb and Mg/Mg_(2)Ca eutectic lamellar alloys when a stress is applied parallel to the lamellar interface,leading to a high yield stress accompanied with ductility.That is,microstructural control can induce a new deformation mode that is not activated in the constituent phases,thereby inducing ductility.It was clarified that the geometric relationship between the operative slip plane in the constituent phases and the lamellar interface,and the microstructural features that provide kink-band nucleation sites are important factors for controlling kink-band formation.The obtained results show a possibility to open the new door for the development of novel high-strength structural material using the kink bands.
基金Supported by Plan Project of Beijing College Students' Scientific Research and Entrepreneurial Action,Major State 973 Program of China(2013CB834400)National Natural Science Foundation of China(11175002,11335002,11375015,11461141002)+2 种基金National Fund for Fostering Talents of Basic Science(NFFTBS)(J1103206)Research Fund for Doctoral Program of Higher Education(20110001110087)China Postdoctoral Science Foundation(2015M580007)
文摘The chiral geometry of multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters γ in the particle rotor model with πh11/2×γh11/2^-1.The energy spectra,electromagnetic transition probabilities B(M1) and B(E2),angular momenta,and K-distributions are studied.It is demonstrated that the chirality still remains not only in the yrast and yrare bands,but also in the two higher excited bands whenγ deviates from 30°.The chiral geometry relies significantly on γ,and the chiral geometry of the two higher excited partner bands is not as good as that of the yrast and yrare doublet bands.
基金supported by the Scientific Challenge Project of China(Grant No.TZ2018001)the National Natural Science Foundation of China(Grant Nos.11627901,11802252)the Science and Technology Program of Sichuan Province(Grant No.2020YFG0415)。
文摘Multiple ballistic impacts are carried out on a 2024-T4 aluminum alloy by spherical steel projectiles(5-mm diameter)at~400 m s^(-1),to investigate its dynamic deformation and damage.The ballistic impact process is captured with high-speed photography.Postmortem samples are characterized with optical imaging,three-dimensional laser scanning,microhardness testing and electron backscatter diffraction.With increasing number of impacts,crater diameter increases slightly,but crater depth and crater volume increase significantly,and strain accumulation leads to microhardness increase overall.Crater parameters all follow power-law relations with the number of impacts.Twin-like deformation bands and macroscopic deformation twins are produced by impact as a result of spontaneous dislocation self-pinning under high strain rate,large shear deformation.Under multiple impacts,shear strain accumulation in the arc-shaped region of the crater induces deformation twinning when it exceeds a critical value(~1.1-1.6).It is highly possible that the deformation twins are related to deformation bands,since they both share one set of the{111}pole with the initial matrix grain.A finite element method model is optimized to reproduce experimental observations and interpret deformation mechanisms.
基金financially supported by the National Natural Science Foundation of China (Nos.51101110,51371122 and 51341006)the Youth Science Foundation of Shanxi Province,China (No.2014021017-3)+1 种基金Technology Foundation for Selected Overseas Chinese Scholar,Ministry of Human Resources and Social Security of Chinathe Program for the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi (2013) and State Key Lab of Advanced Metals and Materials (No.2013-Z03)
文摘The evolution of shear bands in the glassy matrix composites was observed and analyzed during in-situ tension.Based on the simple calculation,the temperature rise within the shear bands is sufficient to cause the formation of viscous shearing layer,resulting in the early failure.Zr-based metallic-glass-matrix composites(labeled as DH1 and DH2) exhibit improved tensile ductility rather than brittle failure,since the existence of secondary ductile dendrites promotes the impedance of prompt propagation of shear bands,evidenced by the multiplication of shear bands.