The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is si...The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.展开更多
This review explores multi-directional functionally graded(MDFG)nanostructures,focusing on their material characteristics,modeling approaches,and mechanical behavior.It starts by classifying different types of functio...This review explores multi-directional functionally graded(MDFG)nanostructures,focusing on their material characteristics,modeling approaches,and mechanical behavior.It starts by classifying different types of functionally graded(FG)materials such as conventional,axial,bi-directional,and tri-directional,and the material distribution models like power-law,exponential,trigonometric,polynomial functions,etc.It also discusses the application of advanced size-dependent theories like Eringen’s nonlocal elasticity,nonlocal strain gradient,modified couple stress,and consistent couple stress theories,which are essential to predict the behavior of structures at small scales.The review covers the mechanical analysis of MDFG nanostructures in nanobeams,nanopipes,nanoplates,and nanoshells and their dynamic and static responses under different loading conditions.The effect of multi-directional material gradation on stiffness,stability and vibration is discussed.Moreover,the review highlights the need for more advanced analytical,semi-analytical,and numerical methods to solve the complex vibration problems ofMDFG nanostructures.It is evident that the continued development of these methods is crucial for the design,optimization,and real-world application of MDFG nanostructures in advanced engineering fields like aerospace,biomedicine,and micro/nanoelectromechanical systems(MEMS/NEMS).This study is a reference for researchers and engineers working in the domain of MDFG nanostructures.展开更多
The homogenized Mg−5.6Gd−0.8Zn(wt.%)alloys were treated with water cooling and furnace cooling to obtain specimens without and with the 14H long-period stacking ordered(LPSO)phase.Subsequently,multi-directional forgin...The homogenized Mg−5.6Gd−0.8Zn(wt.%)alloys were treated with water cooling and furnace cooling to obtain specimens without and with the 14H long-period stacking ordered(LPSO)phase.Subsequently,multi-directional forging(MDF)experiments were carried out.The microstructure and mechanical properties of different regions(the center,middle and edge regions)in the MDFed alloys were systematically investigated,and the effect of LPSO phase on them was discussed.The results show that the alloys in different regions undergo significant grain refinement during the MDF process.Inhomogeneous microstructures with different degrees of dynamic recrystallization(DRX)are formed,resulting in microhardness heterogeneity.The alloy with the LPSO phase has higher microstructure homogeneity,a higher degree of recrystallization,and better comprehensive mechanical properties than the alloy without the LPSO phase.The furnace-cooled alloy after 18 passes of MDF has the best comprehensive mechanical properties,with an ultimate compressive strength of 488 MPa,yield strength of 258 MPa,and fracture strain of 21.2%.DRX behavior is closely related to the LPSO phase and deformation temperature.The kinked LPSO phase can act as a potential nucleation site for DRX grains,while the fragmented LPSO phase promotes DRX nucleation through the particle-stimulated nucleation mechanism.展开更多
The superplasticity of the Mg−8.59Gd−3.85Y−1.14Zn−0.49Zr alloy was investigated before and after multi-directional forging(MDF)and the mechanisms affecting superplastic deformation were analyzed.The results indicate t...The superplasticity of the Mg−8.59Gd−3.85Y−1.14Zn−0.49Zr alloy was investigated before and after multi-directional forging(MDF)and the mechanisms affecting superplastic deformation were analyzed.The results indicate that after MDF at a temperature of 350℃and strain rates of 0.1 and 0.01 s^(−1)(1-MDFed and 2-MDFed),the superplasticity of the alloy can be significantly improved.The elongations of the MDFed alloys exceed 400%under the strain rate of 6.06×10^(−4)s^(−1)and temperatures of 350,375,and 400℃,and reach the maximum values of 766%(1-MDFed)and 693%(2-MDFed)at 375℃.The grain boundary sliding of the MDFed alloy is sufficient,and the energy barrier of deformation decreases.Theβphase limits the grain growth and promotes dynamic recrystallization,maintaining the stability of the fine-grained structure during superplastic deformation.Several Y-rich phases nucleate in the high-strain region(i.e.,the final fracture region)at high temperatures,accelerating the fracture of the specimen.展开更多
An analytical method for analyzing the thermal vibration of multi-directional functionally graded porous rectangular plates in fluid media with novel porosity patterns is developed in this study.Mechanical properties ...An analytical method for analyzing the thermal vibration of multi-directional functionally graded porous rectangular plates in fluid media with novel porosity patterns is developed in this study.Mechanical properties of MFG porous plates change according to the length,width,and thickness directions for various materials and the porosity distribution which can be widely applied in many fields of engineering and defence technology.Especially,new porous rules that depend on spatial coordinates and grading indexes are proposed in the present work.Applying Hamilton's principle and the refined higher-order shear deformation plate theory,the governing equation of motion of an MFG porous rectangular plate in a fluid medium(the fluid-plate system)is obtained.The fluid velocity potential is derived from the boundary conditions of the fluid-plate system and is used to compute the extra mass.The GalerkinVlasov solution is used to solve and give natural frequencies of MFG porous plates with various boundary conditions in a fluid medium.The validity and reliability of the suggested method are confirmed by comparing numerical results of the present work with those from available works in the literature.The effects of different parameters on the thermal vibration response of MFG porous rectangular plates are studied in detail.These findings demonstrate that the behavior of the structure within a liquid medium differs significantly from that within a vacuum medium.Thereby,they offer appropriate operational approaches for the structure when employed in various mediums.展开更多
Reservoir heterogeneities play a crucial role in governing reservoir performance and management.Traditionally,detailed and inter-well heterogeneity analyses are commonly performed by mapping seismic facies change in t...Reservoir heterogeneities play a crucial role in governing reservoir performance and management.Traditionally,detailed and inter-well heterogeneity analyses are commonly performed by mapping seismic facies change in the seismic data,which is a time-intensive task.Many researchers have utilized a robust Grey-level co-occurrence matrix(GLCM)-based texture attributes to map reservoir heterogeneity.However,these attributes take seismic data as input and might not be sensitive to lateral lithology variation.To incorporate the lithology information,we have developed an innovative impedance-based texture approach using GLCM workflow by integrating 3D acoustic impedance volume(a rock propertybased attribute)obtained from a deep convolution network-based impedance inversion.Our proposed workflow is anticipated to be more sensitive toward mapping lateral changes than the conventional amplitude-based texture approach,wherein seismic data is used as input.To evaluate the improvement,we applied the proposed workflow to the full-stack 3D seismic data from the Poseidon field,NW-shelf,Australia.This study demonstrates that a better demarcation of reservoir gas sands with improved lateral continuity is achievable with the presented approach compared to the conventional approach.In addition,we assess the implication of multi-stage faulting on facies distribution for effective reservoir characterization.This study also suggests a well-bounded potential reservoir facies distribution along the parallel fault lines.Thus,the proposed approach provides an efficient strategy by integrating the impedance information with texture attributes to improve the inference on reservoir heterogeneity,which can serve as a promising tool for identifying potential reservoir zones for both production benefits and fluid storage.展开更多
The effect of forging passes on the refinement of high purity aluminum during multi-forging was investigated. The attention was focused on the structure uniformity due to deformation uniformity and the grain refinemen...The effect of forging passes on the refinement of high purity aluminum during multi-forging was investigated. The attention was focused on the structure uniformity due to deformation uniformity and the grain refinement limitation with very high strains. The results show that the fine grain zone in the center of sample expands gradually with the increase of forging passes. When the forging passes reach 6, an X-shape fine grain zone is initially formed. With a further increase of the passes, this X-shape zone tends to spread the whole sample. Limitation in the structural refinement is observed with increasing strains during multi-forging process at the room temperature. The grains size in the center is refined to a certain size （110 μm as forging passes reach 12, and there is no further grain refinement in the center with increasing the forging passes to 24. However, the size of the coarse grains near the surface is continuously decreased with increasing the forging passes to 24.展开更多
Magnesium cylindrical parts have relatively poor mechanical properties and distinct anisotropy of microstructure,which hinder their application as structural components.To improve the performance of WE71 cylindrical p...Magnesium cylindrical parts have relatively poor mechanical properties and distinct anisotropy of microstructure,which hinder their application as structural components.To improve the performance of WE71 cylindrical parts,multi-direction forging(MDF)was introduced before back extrusion,and the microstructure and mechanical properties were investigated.Results of microstructure show that the grain size in the outer of the cylindrical bottom is refined from 30.1 to 27.7μm,the micro structure is more uniform and the dislocation density is higher.The bimodal grain structure is formed in the outer of the cylindrical wall,which is ascribed to the formation of MgsRE phases along grain boundaries.These phases result in the Zener pinning effect on grain boundaries and the reduction of DRX volume fraction.The texture type of the cylindrical bottom is<0001>‖ED and the cylindrical wall is<1010>‖ED,and the maximum pole intensity is 1.986 and 1.664,respectively.Results of the tensile test at room temperature show that combined improved strength and ductility of the cylindrical part is attained after introducing the MDF process.The ultimate tensile strength(UTS),yield strength(YS)and elongation are279 MPa,185 MPa and 12%at the bottom and 299 MPa,212 MPa and 20%at the wall.展开更多
Effect of pre-induced twinning on the microstructure evolution and mechanical properties of extruded Mg-9.26Gd-2.08Y-0.36Zr(GW92K)alloy have been investigated during multi-direction forging with large strains at decre...Effect of pre-induced twinning on the microstructure evolution and mechanical properties of extruded Mg-9.26Gd-2.08Y-0.36Zr(GW92K)alloy have been investigated during multi-direction forging with large strains at decreasing temperature from 400℃ to 300℃.The results showed that,whether there pre-induced twinning existing in the initial microstructure by pre-deformation or not,a mixed microstructure of residual coarse grains and notably refined grains formed under both conditions,combing with some residual coarse grains with less deformation inside grains and lots of dispersed nano-precipitates distributed along refined grain boundaries.However,a significant improvement with the tensile ductility was obtained by the pre-induced twinning in the former alloy.It was suggested that,the pre-induced twinning largely contributed to the grain refinement and lead to an increase in the ratio of fine grain structure which would be responsible for the better properties.Furthermore,during subsequent forging deformation in the pre-deformed sample,the grain refinement mechanism by gradual grain orientation rotation around the surface section in residual coarse-grains was a little different from that by the macro-shear deformation in the as-extruded condition.展开更多
In this study,the Mg-7Gd-5Y-1Nd-0.5Zr alloy can reach a high ductility by the process of multi-directional forging,and the evolution of the microstructure,texture and the mechanical properties were discussed systemati...In this study,the Mg-7Gd-5Y-1Nd-0.5Zr alloy can reach a high ductility by the process of multi-directional forging,and the evolution of the microstructure,texture and the mechanical properties were discussed systematically.The results show that after the solutionized sample was multi-forged at 500℃,its grain size can be refined from 292 um to 58 um.As the forging temperature decreased,fine particles precipitated in the matrix.The volume fraction of the particles increased with the forging temperature decreasing,so the nucleation and growth of crystallization were strongly restricted.There was no recrystallization as the forging temperature fell to 410℃,and the severe deformed grains distributed as streamlines perpendicular to the final compression axis.The texture intensity decreased with increasing forging passes.The sample with best ductility was obtained after compressed at 470℃,with an elongation to failure of 21%at room temperature,which is increased by 200%,in comparison with that of the samples in solutionized condition.EBSD results revealed that the mean grain size was 15 um.Refined grains as well as the weakened texture were the key factors to its high ductility.展开更多
Multi-direction impact forging(MDIF)was applied to the as-extruded ZK60 Mg alloy,and the microstructure,texture evolution and yield strength symmetry were investigated in the current study.The results showed that the ...Multi-direction impact forging(MDIF)was applied to the as-extruded ZK60 Mg alloy,and the microstructure,texture evolution and yield strength symmetry were investigated in the current study.The results showed that the average grain size of forged piece was greatly refined to 5.3μm after 120 forging passes,which was ascribed to the segmenting effect of{10–12}twins and the subsequent multiple rounds of dynamic recrystallization(DRX).A great deal of{10–12}twins were activated at the beginning of MDIF process,which played an important role in grain refinement.With forging proceeding,continuous and discontinuous DRX were successively activated,resulting in the fully DRXed microstructure.Meanwhile,the forged piece exhibited a unique four-peak texture,and the initial<10-10>//ED fiber texture component gradually evolved into multiple texture components composed of<0001>//FFD(first forging direction)and<11–20>//FFD texture.The special strain path was the key to the formation of the unique four-peak texture.The{10–12}twinning and basal slip were two dominant factors to the evolution of texture during MDIF process.Grain strengthening and dislocation strengthening were two main strengthening mechanisms of the forged piece.Besides,the symmetry of yield strength was greatly improved by MDIF process.展开更多
This work discusses tribological properties of commercial pure (CP) titanium processed by multi-directional forging (MDF) up to six passes at room temperature and 220 ℃. For this purpose, wear test was conducted by d...This work discusses tribological properties of commercial pure (CP) titanium processed by multi-directional forging (MDF) up to six passes at room temperature and 220 ℃. For this purpose, wear test was conducted by dry sliding pin-on-disk method on the initial and ultrafine grained samples using different stress magnitudes of 1, 1.5 and 2 MPa. The results showed that wear resistance of CP titanium increases after the first pass of MDF in comparison with the initial condition, irrespective of the applied normal stress. For example, the average wear rate of MDFed samples was decreased about 30% and 24%, after first pass at room temperature and 220 ℃, respectively. However, average wear rate of the samples processed by six MDF passes was reduced about 40% at lower normal loads;it was increased about 9% at higher ones as compared to the initial condition. It was also found that the dominated wear mechanisms were abrasive and delaminated at the lower stresses, while the delamination mechanism was intensified and a slight adhesion was observed during the higher applied normal loads.展开更多
Measuring multi-directional waves with the wave gauge array is one of the fundamental and easily realised methods. In this paper, the wave gauge array is described and the effects of the gauge spacing, the array orien...Measuring multi-directional waves with the wave gauge array is one of the fundamental and easily realised methods. In this paper, the wave gauge array is described and the effects of the gauge spacing, the array orientations, etc. of the three array arrangements, i. e., linear array, T-type array and pentagon array, on the resolution of the directional spreading of waves, are investigated experimentally. This study can be used as a reference in the experimental study and the field measurement of directional waves.展开更多
Effect of multi-directional forging(MDF)on wear properties of Mg-Zn alloys(with 2,4,and 6wt%Zn)is investigated.Dry sliding wear test was performed using pin on disk machine on MDF processed and homogenized samples.Wea...Effect of multi-directional forging(MDF)on wear properties of Mg-Zn alloys(with 2,4,and 6wt%Zn)is investigated.Dry sliding wear test was performed using pin on disk machine on MDF processed and homogenized samples.Wear behavior of samples was analyzed at loads of ION and 20 N,with sliding distances of 2000m and 4000m,at a sliding velocity of 3m/s.Microstructures of worn samples were observed under scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and x-ray diffraction(XRD)and the results were analyzed.Mechanical properties were evaluated using microhardness test.After 5 passes of MDF,the average grain size was found to be 30±4p m,22±3 pm,and 18±3 pm,in Mg-2%Zn,Mg-4%Zn,and Mg-6%Zn alloys,respectively,with significant improvement in hardness in all cases.Wear resistance was improved after MDF processing,as well as,with increment in Zn content in Mg alloy.However,it decreased when the load and the sliding distance increased.Worn surface exhibited ploughing,delamination,plastic deformation,and wear debris along sliding direction,and abrasive wear was found to be the main mechanism.展开更多
To predict the performance of multi-direction piezoelectric vibration energy harvester,an equation for calculating its output power is obtained based on elastic mechanics theory and piezoelectricity theory.Experiments...To predict the performance of multi-direction piezoelectric vibration energy harvester,an equation for calculating its output power is obtained based on elastic mechanics theory and piezoelectricity theory.Experiments are performed to verify theoretical analysis.When the excitation direction is along Y direction,a maximal output power about 0.139 mW can be harvested at a resistive load of 65kΩ and an excitation frequency of 136 Hz.Theoretical analysis agrees well with experimental results.Furthermore,the performance of multi-direction vibration energy harvester is experimentally tested.The results show that the multi-direction vibration energy harvester can harvest perfect energy as the excitation direction changes in XY plane,YZ plane,XZ plane and body diagonal plane of the harvester.展开更多
In this study,the mechanical properties and damping capacities of cast Mg-5.5 Zn-0.6 Zr(weight percent,ZK60)alloys have been simultaneously improved by a facile multi-directional forging(MDF)processing,and the mechani...In this study,the mechanical properties and damping capacities of cast Mg-5.5 Zn-0.6 Zr(weight percent,ZK60)alloys have been simultaneously improved by a facile multi-directional forging(MDF)processing,and the mechanisms of microstructure evolution and texture modification are systematically investigated.The activation of tension twinning occurs during the initial MDF stage,due to the coarse-grained structure of the as-cast alloy.With increasing MDF passes,the continuous dynamic recrystallization(CDRX)results in a fine equiaxed-grain structure.The typical non-basal texture is formed in the as-MDFed alloy for 6 passes,with the(0001)planes inclined 60°–70°to forged direction and 10°–20°to transverse direction,respectively.A good balance between the strength(~194.9 MPa)and ductility(~24.9%)has been achieved,which can be ascribed to the grain refinement,non-basal texture and fine precipitate particles.The damping capacity is remarkably improved after MDF processing,because the severe deformation increases the dislocation density,which effectively enlarges the sweep areas of mobile dislocations.展开更多
The three-dimensional free vibration analysis of a multi-directional func- tionally graded piezoelectric （FGP） annular plate resting on two parameter （Pasternak） elastic foundations is investigated under different...The three-dimensional free vibration analysis of a multi-directional func- tionally graded piezoelectric （FGP） annular plate resting on two parameter （Pasternak） elastic foundations is investigated under different boundary conditions. The material properties are assumed to vary continuously along the radial and thickness directions and have exponent-law distribution. A semi-analytical approach named the state space based differential quadrature method （SSDQM） is used to provide an analytical solution along the thickness using the state space method （SSM） and an approximate solution along the radial direction using the one-dimensional differential quadrature method （DQM）. The influence of the Winkler and shear stiffness of the foundation~ the material property graded variations, and the circumferential wave number on the nomdimensional natural frequency of multi-directional FGP annular plates is studied.展开更多
Bending Pneumatic Artificial Muscles(PAMs)are particularly attractive and extensively applied to the soft grasper,snake-like robot,etc.To extend the application of PAMs,we fabricate a Multi-directional Bending Pneumat...Bending Pneumatic Artificial Muscles(PAMs)are particularly attractive and extensively applied to the soft grasper,snake-like robot,etc.To extend the application of PAMs,we fabricate a Multi-directional Bending Pneumatic Artificial Muscle(MBPAM)that can bend in eight directions by changing the pressurized chambers.The maximum bending angle and output force are 151°and 0.643 N under the pressure of 100 kPa,respectively.Additionally,the Finite Element Model(FEM)is established to further investigate the performance.The experimental and numerical results demonstrate the nonlinear relationship between the pressure and the bending angle and output force.Moreover,the effects of parameters on the performance are studied with the validated FEM.The results reveal that the amplitude of waves and the thickness of the base layer can be optimized.Thus,multi-objective optimization is performed to improve the bending performance of the MBPAM.The optimization results indicate that the output force can be increased by 7.8%with the identical bending angle of the initial design,while the bending angle can be improved by 8.6%with the same output force.Finally,the grasp tests demonstrate the grip capability of the soft four-finger gripper and display the application prospect of the MBPAM in soft robots.展开更多
This paper presents the design, analysis and experimental study of a loading system for heavy-duty nodes test based on a large-scale multi-directional in-plane loading device, which has been used in a full-scale heavy...This paper presents the design, analysis and experimental study of a loading system for heavy-duty nodes test based on a large-scale multi-directional in-plane loading device, which has been used in a full-scale heavy-duty support node test. Test loads of the support reached 6 567 kN with multi-directional loading requirements, which outrange the capacity of the available loading devices. Through the reinforcement of a large-scale multi-directional inplane loading device, the innovative design of a self-balanced load transferring device, and other arrangement considerations of the loading system, the test was implemented and the loading capacity of the ring was considerably enlarged. Due to the heavy loading requirements, some checking computations of the ring and the load transferring device outranged the limit of the Chinese national code "Code for Design of Steel Structures (GB 50017—2003)", thus elastic-plastic finite element (FE) analysis was carried out on the two devices, and also the real-time monitoring on the whole loading systems during experiments to ensure test safety. FE analysis and test results show that the loading system worked elastically during experiments.展开更多
Extensive 3-D model tests have been performed to study the effects of wave obliquity and multi-directionality on the wave loads acting on vertical breakwaters. The variation of horizontal and uplift forces acting on a...Extensive 3-D model tests have been performed to study the effects of wave obliquity and multi-directionality on the wave loads acting on vertical breakwaters. The variation of horizontal and uplift forces acting on an unit length of a breakwater with wave direction, the longitudinal distribution of wave forces, as well as the longitudinal load reduction are analyzed. Some empirical formulae of the longitudinal distribution coefficient and the longitudinal load reduction factor are presented for practical use.展开更多
基金This study was jointly supported by the Science&Technology Fundamental Resources Investigation Program(2022FY101800)National Science Foundation(92162212)+1 种基金the project from the Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences,Wuhan)(TPR-2022-22)the International Geoscience Programme(IGCP-675)。
文摘The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.
文摘This review explores multi-directional functionally graded(MDFG)nanostructures,focusing on their material characteristics,modeling approaches,and mechanical behavior.It starts by classifying different types of functionally graded(FG)materials such as conventional,axial,bi-directional,and tri-directional,and the material distribution models like power-law,exponential,trigonometric,polynomial functions,etc.It also discusses the application of advanced size-dependent theories like Eringen’s nonlocal elasticity,nonlocal strain gradient,modified couple stress,and consistent couple stress theories,which are essential to predict the behavior of structures at small scales.The review covers the mechanical analysis of MDFG nanostructures in nanobeams,nanopipes,nanoplates,and nanoshells and their dynamic and static responses under different loading conditions.The effect of multi-directional material gradation on stiffness,stability and vibration is discussed.Moreover,the review highlights the need for more advanced analytical,semi-analytical,and numerical methods to solve the complex vibration problems ofMDFG nanostructures.It is evident that the continued development of these methods is crucial for the design,optimization,and real-world application of MDFG nanostructures in advanced engineering fields like aerospace,biomedicine,and micro/nanoelectromechanical systems(MEMS/NEMS).This study is a reference for researchers and engineers working in the domain of MDFG nanostructures.
基金the financial supports from the Key Research and Development Program of Hunan Province,China(No.2023GK2020)。
文摘The homogenized Mg−5.6Gd−0.8Zn(wt.%)alloys were treated with water cooling and furnace cooling to obtain specimens without and with the 14H long-period stacking ordered(LPSO)phase.Subsequently,multi-directional forging(MDF)experiments were carried out.The microstructure and mechanical properties of different regions(the center,middle and edge regions)in the MDFed alloys were systematically investigated,and the effect of LPSO phase on them was discussed.The results show that the alloys in different regions undergo significant grain refinement during the MDF process.Inhomogeneous microstructures with different degrees of dynamic recrystallization(DRX)are formed,resulting in microhardness heterogeneity.The alloy with the LPSO phase has higher microstructure homogeneity,a higher degree of recrystallization,and better comprehensive mechanical properties than the alloy without the LPSO phase.The furnace-cooled alloy after 18 passes of MDF has the best comprehensive mechanical properties,with an ultimate compressive strength of 488 MPa,yield strength of 258 MPa,and fracture strain of 21.2%.DRX behavior is closely related to the LPSO phase and deformation temperature.The kinked LPSO phase can act as a potential nucleation site for DRX grains,while the fragmented LPSO phase promotes DRX nucleation through the particle-stimulated nucleation mechanism.
基金supported by the National Natural Science Foundation of China(No.52127808)。
文摘The superplasticity of the Mg−8.59Gd−3.85Y−1.14Zn−0.49Zr alloy was investigated before and after multi-directional forging(MDF)and the mechanisms affecting superplastic deformation were analyzed.The results indicate that after MDF at a temperature of 350℃and strain rates of 0.1 and 0.01 s^(−1)(1-MDFed and 2-MDFed),the superplasticity of the alloy can be significantly improved.The elongations of the MDFed alloys exceed 400%under the strain rate of 6.06×10^(−4)s^(−1)and temperatures of 350,375,and 400℃,and reach the maximum values of 766%(1-MDFed)and 693%(2-MDFed)at 375℃.The grain boundary sliding of the MDFed alloy is sufficient,and the energy barrier of deformation decreases.Theβphase limits the grain growth and promotes dynamic recrystallization,maintaining the stability of the fine-grained structure during superplastic deformation.Several Y-rich phases nucleate in the high-strain region(i.e.,the final fracture region)at high temperatures,accelerating the fracture of the specimen.
文摘An analytical method for analyzing the thermal vibration of multi-directional functionally graded porous rectangular plates in fluid media with novel porosity patterns is developed in this study.Mechanical properties of MFG porous plates change according to the length,width,and thickness directions for various materials and the porosity distribution which can be widely applied in many fields of engineering and defence technology.Especially,new porous rules that depend on spatial coordinates and grading indexes are proposed in the present work.Applying Hamilton's principle and the refined higher-order shear deformation plate theory,the governing equation of motion of an MFG porous rectangular plate in a fluid medium(the fluid-plate system)is obtained.The fluid velocity potential is derived from the boundary conditions of the fluid-plate system and is used to compute the extra mass.The GalerkinVlasov solution is used to solve and give natural frequencies of MFG porous plates with various boundary conditions in a fluid medium.The validity and reliability of the suggested method are confirmed by comparing numerical results of the present work with those from available works in the literature.The effects of different parameters on the thermal vibration response of MFG porous rectangular plates are studied in detail.These findings demonstrate that the behavior of the structure within a liquid medium differs significantly from that within a vacuum medium.Thereby,they offer appropriate operational approaches for the structure when employed in various mediums.
文摘Reservoir heterogeneities play a crucial role in governing reservoir performance and management.Traditionally,detailed and inter-well heterogeneity analyses are commonly performed by mapping seismic facies change in the seismic data,which is a time-intensive task.Many researchers have utilized a robust Grey-level co-occurrence matrix(GLCM)-based texture attributes to map reservoir heterogeneity.However,these attributes take seismic data as input and might not be sensitive to lateral lithology variation.To incorporate the lithology information,we have developed an innovative impedance-based texture approach using GLCM workflow by integrating 3D acoustic impedance volume(a rock propertybased attribute)obtained from a deep convolution network-based impedance inversion.Our proposed workflow is anticipated to be more sensitive toward mapping lateral changes than the conventional amplitude-based texture approach,wherein seismic data is used as input.To evaluate the improvement,we applied the proposed workflow to the full-stack 3D seismic data from the Poseidon field,NW-shelf,Australia.This study demonstrates that a better demarcation of reservoir gas sands with improved lateral continuity is achievable with the presented approach compared to the conventional approach.In addition,we assess the implication of multi-stage faulting on facies distribution for effective reservoir characterization.This study also suggests a well-bounded potential reservoir facies distribution along the parallel fault lines.Thus,the proposed approach provides an efficient strategy by integrating the impedance information with texture attributes to improve the inference on reservoir heterogeneity,which can serve as a promising tool for identifying potential reservoir zones for both production benefits and fluid storage.
基金Projects(51204053,51074048,51204048)supported by the National Natural Science Foundation of ChinaProject(20110491518)supported by China Postdoctoral Science FoundationProject(2012CB619506)supported by the National Basic Research Program of China
文摘The effect of forging passes on the refinement of high purity aluminum during multi-forging was investigated. The attention was focused on the structure uniformity due to deformation uniformity and the grain refinement limitation with very high strains. The results show that the fine grain zone in the center of sample expands gradually with the increase of forging passes. When the forging passes reach 6, an X-shape fine grain zone is initially formed. With a further increase of the passes, this X-shape zone tends to spread the whole sample. Limitation in the structural refinement is observed with increasing strains during multi-forging process at the room temperature. The grains size in the center is refined to a certain size （110 μm as forging passes reach 12, and there is no further grain refinement in the center with increasing the forging passes to 24. However, the size of the coarse grains near the surface is continuously decreased with increasing the forging passes to 24.
基金Project supported by the General Program of National Natural Science Foundation of China(51871195,51501015)。
文摘Magnesium cylindrical parts have relatively poor mechanical properties and distinct anisotropy of microstructure,which hinder their application as structural components.To improve the performance of WE71 cylindrical parts,multi-direction forging(MDF)was introduced before back extrusion,and the microstructure and mechanical properties were investigated.Results of microstructure show that the grain size in the outer of the cylindrical bottom is refined from 30.1 to 27.7μm,the micro structure is more uniform and the dislocation density is higher.The bimodal grain structure is formed in the outer of the cylindrical wall,which is ascribed to the formation of MgsRE phases along grain boundaries.These phases result in the Zener pinning effect on grain boundaries and the reduction of DRX volume fraction.The texture type of the cylindrical bottom is<0001>‖ED and the cylindrical wall is<1010>‖ED,and the maximum pole intensity is 1.986 and 1.664,respectively.Results of the tensile test at room temperature show that combined improved strength and ductility of the cylindrical part is attained after introducing the MDF process.The ultimate tensile strength(UTS),yield strength(YS)and elongation are279 MPa,185 MPa and 12%at the bottom and 299 MPa,212 MPa and 20%at the wall.
基金The authors gratefully acknowledge financial support from the National Basic Research Program of China(973 Program)through project no.2013CB632202National Natural Science Foundation of China(NSFC)through project no.51105350.
文摘Effect of pre-induced twinning on the microstructure evolution and mechanical properties of extruded Mg-9.26Gd-2.08Y-0.36Zr(GW92K)alloy have been investigated during multi-direction forging with large strains at decreasing temperature from 400℃ to 300℃.The results showed that,whether there pre-induced twinning existing in the initial microstructure by pre-deformation or not,a mixed microstructure of residual coarse grains and notably refined grains formed under both conditions,combing with some residual coarse grains with less deformation inside grains and lots of dispersed nano-precipitates distributed along refined grain boundaries.However,a significant improvement with the tensile ductility was obtained by the pre-induced twinning in the former alloy.It was suggested that,the pre-induced twinning largely contributed to the grain refinement and lead to an increase in the ratio of fine grain structure which would be responsible for the better properties.Furthermore,during subsequent forging deformation in the pre-deformed sample,the grain refinement mechanism by gradual grain orientation rotation around the surface section in residual coarse-grains was a little different from that by the macro-shear deformation in the as-extruded condition.
基金Project supported by the National Foundation of Natural Science(No.51105350 and No.51301173)project 973(No.2013CB632202)of National Ministry of Science and Technology+1 种基金This work was funded by the National Basic Research Program of China(973 Program)through project No.2013CB632202National Natural Science Foundation of China(NSFC)through projects No.51105350 and No.51301173,respectively.
文摘In this study,the Mg-7Gd-5Y-1Nd-0.5Zr alloy can reach a high ductility by the process of multi-directional forging,and the evolution of the microstructure,texture and the mechanical properties were discussed systematically.The results show that after the solutionized sample was multi-forged at 500℃,its grain size can be refined from 292 um to 58 um.As the forging temperature decreased,fine particles precipitated in the matrix.The volume fraction of the particles increased with the forging temperature decreasing,so the nucleation and growth of crystallization were strongly restricted.There was no recrystallization as the forging temperature fell to 410℃,and the severe deformed grains distributed as streamlines perpendicular to the final compression axis.The texture intensity decreased with increasing forging passes.The sample with best ductility was obtained after compressed at 470℃,with an elongation to failure of 21%at room temperature,which is increased by 200%,in comparison with that of the samples in solutionized condition.EBSD results revealed that the mean grain size was 15 um.Refined grains as well as the weakened texture were the key factors to its high ductility.
基金supported by National Natural Science Foundation of China(Grant No.51975146)Key Research and Development Plan in Shandong Province(Grant No.2018JMRH0412,2019JZZY010364)National Defense Basic Scientific Research of China(Grant no.JCK2018603C017)。
文摘Multi-direction impact forging(MDIF)was applied to the as-extruded ZK60 Mg alloy,and the microstructure,texture evolution and yield strength symmetry were investigated in the current study.The results showed that the average grain size of forged piece was greatly refined to 5.3μm after 120 forging passes,which was ascribed to the segmenting effect of{10–12}twins and the subsequent multiple rounds of dynamic recrystallization(DRX).A great deal of{10–12}twins were activated at the beginning of MDIF process,which played an important role in grain refinement.With forging proceeding,continuous and discontinuous DRX were successively activated,resulting in the fully DRXed microstructure.Meanwhile,the forged piece exhibited a unique four-peak texture,and the initial<10-10>//ED fiber texture component gradually evolved into multiple texture components composed of<0001>//FFD(first forging direction)and<11–20>//FFD texture.The special strain path was the key to the formation of the unique four-peak texture.The{10–12}twinning and basal slip were two dominant factors to the evolution of texture during MDIF process.Grain strengthening and dislocation strengthening were two main strengthening mechanisms of the forged piece.Besides,the symmetry of yield strength was greatly improved by MDIF process.
基金supported financially by the Iran National Science Foundation (No.94809610)the Czech Science Foundation Project (No.GB 14-36566G)
文摘This work discusses tribological properties of commercial pure (CP) titanium processed by multi-directional forging (MDF) up to six passes at room temperature and 220 ℃. For this purpose, wear test was conducted by dry sliding pin-on-disk method on the initial and ultrafine grained samples using different stress magnitudes of 1, 1.5 and 2 MPa. The results showed that wear resistance of CP titanium increases after the first pass of MDF in comparison with the initial condition, irrespective of the applied normal stress. For example, the average wear rate of MDFed samples was decreased about 30% and 24%, after first pass at room temperature and 220 ℃, respectively. However, average wear rate of the samples processed by six MDF passes was reduced about 40% at lower normal loads;it was increased about 9% at higher ones as compared to the initial condition. It was also found that the dominated wear mechanisms were abrasive and delaminated at the lower stresses, while the delamination mechanism was intensified and a slight adhesion was observed during the higher applied normal loads.
文摘Measuring multi-directional waves with the wave gauge array is one of the fundamental and easily realised methods. In this paper, the wave gauge array is described and the effects of the gauge spacing, the array orientations, etc. of the three array arrangements, i. e., linear array, T-type array and pentagon array, on the resolution of the directional spreading of waves, are investigated experimentally. This study can be used as a reference in the experimental study and the field measurement of directional waves.
文摘Effect of multi-directional forging(MDF)on wear properties of Mg-Zn alloys(with 2,4,and 6wt%Zn)is investigated.Dry sliding wear test was performed using pin on disk machine on MDF processed and homogenized samples.Wear behavior of samples was analyzed at loads of ION and 20 N,with sliding distances of 2000m and 4000m,at a sliding velocity of 3m/s.Microstructures of worn samples were observed under scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and x-ray diffraction(XRD)and the results were analyzed.Mechanical properties were evaluated using microhardness test.After 5 passes of MDF,the average grain size was found to be 30±4p m,22±3 pm,and 18±3 pm,in Mg-2%Zn,Mg-4%Zn,and Mg-6%Zn alloys,respectively,with significant improvement in hardness in all cases.Wear resistance was improved after MDF processing,as well as,with increment in Zn content in Mg alloy.However,it decreased when the load and the sliding distance increased.Worn surface exhibited ploughing,delamination,plastic deformation,and wear debris along sliding direction,and abrasive wear was found to be the main mechanism.
基金Supported by the National Natural Science Foundation of China(51305183)the Qing Lan Project of Jiangsu Provincethe Doctoral Start-up Foundation of Jinling Institute of Technology(jit-b-201412)
文摘To predict the performance of multi-direction piezoelectric vibration energy harvester,an equation for calculating its output power is obtained based on elastic mechanics theory and piezoelectricity theory.Experiments are performed to verify theoretical analysis.When the excitation direction is along Y direction,a maximal output power about 0.139 mW can be harvested at a resistive load of 65kΩ and an excitation frequency of 136 Hz.Theoretical analysis agrees well with experimental results.Furthermore,the performance of multi-direction vibration energy harvester is experimentally tested.The results show that the multi-direction vibration energy harvester can harvest perfect energy as the excitation direction changes in XY plane,YZ plane,XZ plane and body diagonal plane of the harvester.
基金financially supported by the National Natural Science Foundation of China(No.51771178)the Shanxi Provincial Key Research and Development Project(Nos.2020KWZ-007,2018ZDXM-GY-149)the Natural Science Foundation of Jilin Province(No.20180414016GH)。
文摘In this study,the mechanical properties and damping capacities of cast Mg-5.5 Zn-0.6 Zr(weight percent,ZK60)alloys have been simultaneously improved by a facile multi-directional forging(MDF)processing,and the mechanisms of microstructure evolution and texture modification are systematically investigated.The activation of tension twinning occurs during the initial MDF stage,due to the coarse-grained structure of the as-cast alloy.With increasing MDF passes,the continuous dynamic recrystallization(CDRX)results in a fine equiaxed-grain structure.The typical non-basal texture is formed in the as-MDFed alloy for 6 passes,with the(0001)planes inclined 60°–70°to forged direction and 10°–20°to transverse direction,respectively.A good balance between the strength(~194.9 MPa)and ductility(~24.9%)has been achieved,which can be ascribed to the grain refinement,non-basal texture and fine precipitate particles.The damping capacity is remarkably improved after MDF processing,because the severe deformation increases the dislocation density,which effectively enlarges the sweep areas of mobile dislocations.
文摘The three-dimensional free vibration analysis of a multi-directional func- tionally graded piezoelectric （FGP） annular plate resting on two parameter （Pasternak） elastic foundations is investigated under different boundary conditions. The material properties are assumed to vary continuously along the radial and thickness directions and have exponent-law distribution. A semi-analytical approach named the state space based differential quadrature method （SSDQM） is used to provide an analytical solution along the thickness using the state space method （SSM） and an approximate solution along the radial direction using the one-dimensional differential quadrature method （DQM）. The influence of the Winkler and shear stiffness of the foundation~ the material property graded variations, and the circumferential wave number on the nomdimensional natural frequency of multi-directional FGP annular plates is studied.
基金the National Natural Science Foundation of China(11872178,51621004)are gratefully acknowledged。
文摘Bending Pneumatic Artificial Muscles(PAMs)are particularly attractive and extensively applied to the soft grasper,snake-like robot,etc.To extend the application of PAMs,we fabricate a Multi-directional Bending Pneumatic Artificial Muscle(MBPAM)that can bend in eight directions by changing the pressurized chambers.The maximum bending angle and output force are 151°and 0.643 N under the pressure of 100 kPa,respectively.Additionally,the Finite Element Model(FEM)is established to further investigate the performance.The experimental and numerical results demonstrate the nonlinear relationship between the pressure and the bending angle and output force.Moreover,the effects of parameters on the performance are studied with the validated FEM.The results reveal that the amplitude of waves and the thickness of the base layer can be optimized.Thus,multi-objective optimization is performed to improve the bending performance of the MBPAM.The optimization results indicate that the output force can be increased by 7.8%with the identical bending angle of the initial design,while the bending angle can be improved by 8.6%with the same output force.Finally,the grasp tests demonstrate the grip capability of the soft four-finger gripper and display the application prospect of the MBPAM in soft robots.
基金Supported by National Natural Science Foundation of China (No. 50878066)the National Key Technology R&D Program in the 11th Five-Year Plan of China (No. 2006BAJ01B02)the Key Technologies R&D Program of Heilongjiang Province, China (No. GB02C204)
文摘This paper presents the design, analysis and experimental study of a loading system for heavy-duty nodes test based on a large-scale multi-directional in-plane loading device, which has been used in a full-scale heavy-duty support node test. Test loads of the support reached 6 567 kN with multi-directional loading requirements, which outrange the capacity of the available loading devices. Through the reinforcement of a large-scale multi-directional inplane loading device, the innovative design of a self-balanced load transferring device, and other arrangement considerations of the loading system, the test was implemented and the loading capacity of the ring was considerably enlarged. Due to the heavy loading requirements, some checking computations of the ring and the load transferring device outranged the limit of the Chinese national code "Code for Design of Steel Structures (GB 50017—2003)", thus elastic-plastic finite element (FE) analysis was carried out on the two devices, and also the real-time monitoring on the whole loading systems during experiments to ensure test safety. FE analysis and test results show that the loading system worked elastically during experiments.
文摘Extensive 3-D model tests have been performed to study the effects of wave obliquity and multi-directionality on the wave loads acting on vertical breakwaters. The variation of horizontal and uplift forces acting on an unit length of a breakwater with wave direction, the longitudinal distribution of wave forces, as well as the longitudinal load reduction are analyzed. Some empirical formulae of the longitudinal distribution coefficient and the longitudinal load reduction factor are presented for practical use.
