A compound varifocal lens based on electromagnetic drive technology is designed and fabricated, where the polydimethylsiloxane(PDMS) film acts as a driving component, while the PDMS biconvex lens and the plane-concave...A compound varifocal lens based on electromagnetic drive technology is designed and fabricated, where the polydimethylsiloxane(PDMS) film acts as a driving component, while the PDMS biconvex lens and the plane-concave lens form a coaxial compound lens system. The plane-concave lens equipped with driving coils is installed directly above the PDMS lens surrounded by the annular magnet. When different currents are applied, the annular magnet moves up and down, driving the PDMS film to undergo elastic deformation, and then resulting in longitudinal movement of the PDMS lens. The position change of the PDMS lens changes the focal length of the compound lens system. To verify the feasibility and practicability of this design, a prototype of our compound lens system is fabricated in experiment. Our proposed compound lens shows that its zoom ability reaches 9.28 mm when the current ranges from -0.20 A to 0.21 A.展开更多
A classic hysteretic model, Preisach-Mayergoyz model （P-M model）, was used to calculate the nonlinear elastic deformation of magnesium （Mg） and cobalt （Co）. Mg and Co samples in cylinder shape were compressively...A classic hysteretic model, Preisach-Mayergoyz model （P-M model）, was used to calculate the nonlinear elastic deformation of magnesium （Mg） and cobalt （Co）. Mg and Co samples in cylinder shape were compressively tested by uniaxial test machine to obtain their stress—strain curves with hysteretic loops. The hysteretic loops do have two properties of P-M hysteretic systems： wiping out and congruency. It is proved that P-M model is applicable for the analysis of these two metals’ hysteresis. This model was applied on Mg at room temperature and Co at 300 ℃. By the P-M model, Co and Mg nonlinear elastic deformation can be calculated based on the stress history. The simulated stress—strain curves agree well with the experimental results. Therefore, the mechanical hysteresis of these two metals can be easily predicted by the classic P-M hysteretic model.展开更多
The calculation error of the gauge-meter model will affect the gap setting precision and the self-learn precision of rolling force. The precision of the gauge-meter model is strongly influenced by plate width, working...The calculation error of the gauge-meter model will affect the gap setting precision and the self-learn precision of rolling force. The precision of the gauge-meter model is strongly influenced by plate width, working roll radius, backup roll radius, working roll crown, backup roll crown, and rolling force. The influence rules are hard to get by measuring. Taking a conventional 4-h plate mill as the research subject, these influences were transferred into the calculation of roll deflection and flattening deformation. To calculate these deformations, the theory of the influence function method was adopted. By modifying the traditional gauge-meter model, a novel model of the effect of roll elastic deformation on the gap setting was built by data fitting. By this model, it was convenient to analyze the variation caused by the rolling condition. Combining the elastic deformation model of rolls with the kiss-rolls method, a gauge-meter model was put forward for plate thickness prediction. The prediction precision of thickness was greatly improved by the new gauge- meter model.展开更多
The buoyancy driven flow of a second-grade nanofluid in the presence of a binary chemical reaction is analyzed in the context of a model based on the balance equations for mass,species concentration,momentum and energ...The buoyancy driven flow of a second-grade nanofluid in the presence of a binary chemical reaction is analyzed in the context of a model based on the balance equations for mass,species concentration,momentum and energy.The elastic properties of the considered fluid are taken into account.The two-dimensional slip flow of such non-Newtonian fluid over a porous flat material which is stretched vertically upwards is considered.The role played by the activation energy is accounted for through an exponent form modified Arrhenius function added to the Buongiorno model for the nanofluid concentration.The effects of thermal radiation are also examined.A similarity transformations is used to turn the problem based on partial differential equations into a system of ordinary differential equations.The resulting system is solved using a fourth order RK and shooting methods.The velocity profile,temperature profile,concentration profile,local skin friction,local Nusselt number and local Sherwood number are reported for several circumstances.The influence of the chemical reaction on the properties of the concentration and momentum boundary layers is critically discussed.展开更多
The error of gaugemeter equation decreases the gap setting precision.The precision of gaugemeter equation is strongly influenced by plate width,work roll radius,backup roll radius,work roll crown,backup roll crown and...The error of gaugemeter equation decreases the gap setting precision.The precision of gaugemeter equation is strongly influenced by plate width,work roll radius,backup roll radius,work roll crown,backup roll crown and rolling force.And these influences are hard to measure.All these factors are converted to roll deflection deformation and roll flattening deformation for calculation.In order to calculate the deformation,the theory of influence function method was adopted.By using simulation program,the influence of these factors on deformation was obtained.Then a simple model can be built.With this model,it is convenient to analyze the influence of different factors on gaugemeter equation.展开更多
In this work,the underlying mechanism responsible for the near-linear elastic deformation behavior of a dual-phase Ti-Nb alloy consisting of β and α'' phase with large recoverable strain was systematically e...In this work,the underlying mechanism responsible for the near-linear elastic deformation behavior of a dual-phase Ti-Nb alloy consisting of β and α'' phase with large recoverable strain was systematically elucidated.Based on in situ synchrotron X-ray diffraction(SXRD)analyses,it was found that besides intrinsic elastic deformation,a slight reversible β-α'' stress-induced martensitic(SIM)transformation,which proceeded in a consecutive mode under the retarding effect of micro-defects,took place during the near-linear elastic deformation.After unloading,a small amount of residual macroscopic strain remained in the specimen due to the incomplete reverse α''→β transformation on unloading.The high near-linear elastic deformability of the cold drawing(CD)Ti-Nb alloy has been revealed to be attributed to the coupling actions of intrinsic elasticity as well as the consecutive and reversible β-α'' SIM transformation.Our research may contribute to a new avenue for the design and development of novel dual-phase Ti-based alloys with desirable elastic deformability.展开更多
Precision prediction of machined surface roughness is challenging facing the robotic belt grinding of complex blade,since this process is accompanied by significant elastic deformation.The resulting poor prediction ac...Precision prediction of machined surface roughness is challenging facing the robotic belt grinding of complex blade,since this process is accompanied by significant elastic deformation.The resulting poor prediction accuracy,to a great extent,is attributed to the existing prediction model which less considers the dynamics.In this paper,an improved scallop height model is developed to predict and assess the machined surface roughness by taking into account the elastic deformation and the varying curvature of blade,then robotic belt grinding experiments are carried out to evaluate the proposed model from the perspective of surface roughness.Finally factors that influence the scallop height are analyzed,and the suitable empirical equation of surface roughness is proposed to assess and predict the surface quality from the aspect of blade concave and convex surface by adopting the constant scallop height machining.展开更多
This communication is devoted to analyze elastic deformation on electrically conducted viscoelastic fluid in the presence of viscous dissipation effects. Non-linear analysis is computed through exact solutions for vel...This communication is devoted to analyze elastic deformation on electrically conducted viscoelastic fluid in the presence of viscous dissipation effects. Non-linear analysis is computed through exact solutions for velocity,temperature and concentration profiles. Special emphasis is provided for elastic deformation in the presence of magnetohydrodynamics effects. Concentration profile is discussed significantly in the presence constructive and destructive chemical reaction. Results are displayed through graphs and discussed for physical parameters that are used in present analysis. Notable findings include that temperature and thermal boundary layer thickness is an increasing function of Prandtl number and a decreasing function of elastic deformation. In addition, heat transfer rate is enhanced by increasing the conjugate parameter(γ) which measures the strength of surface heating.展开更多
The room temperature brittleness has been a long standing problem in bulk metallic glasses realm.This has seriously limited the application potential of metallic glasses and their composites.The elastic deformation be...The room temperature brittleness has been a long standing problem in bulk metallic glasses realm.This has seriously limited the application potential of metallic glasses and their composites.The elastic deformation behaviors of metallic glass matrix composites are closely related to their plastic deformation states.The elastic deformation behaviors of Cu48-xZr48Al4Nbx（x=0,3at.%）metallic glass matrix composites（MGMCs）with different crystallization degrees were investigated using an in-situ digital image correlation（DIC）technique during tensile process.With decreasing crystallization degree,MGMC exhibits obvious elastic deformation ability and an increased tensile fracture strength.The notable tensile elasticity is attributed to the larger shear strain heterogeneity emerging on the surface of the sample.This finding has implications for the development of MGMCs with excellent tensile properties.展开更多
Based on the new viewpoint of solid and gas interaction mechanics, gas leakage in a double deformable coal seam can be understood. That is, under the action of geophysical fields, the methane flow in a double deformab...Based on the new viewpoint of solid and gas interaction mechanics, gas leakage in a double deformable coal seam can be understood. That is, under the action of geophysical fields, the methane flow in a double deformable coal seam can be essentially considered to be compressible with time dependent and mixed permeation and diffusion through a pore cleat deformable heterogeneous and anisotropy medium. Based on this new viewpoint, a coupled mathematical model for coal seam deformation and gas leakage in a double coal seam was formulated and numerical simulations for gas emission from the coal seam are presented. It is found that coupled models might be closer to reality.展开更多
A flew numerical method for constructing a pressure distribution to calculate surface elastic deformationcaused by normal contact pressure is developed in this paper. The pressure distribution over one of nonequidista...A flew numerical method for constructing a pressure distribution to calculate surface elastic deformationcaused by normal contact pressure is developed in this paper. The pressure distribution over one of nonequidistantrectangles is fitted by an approximate tangent plane(ATP), which is formed by five pressure samples. Because thepressure distribution could be expressed as an one order linear polynomial, the iterative expression of elasticdeformation deduced by this method is simple, and the numerical accuracy is higher.展开更多
In this paper. we obtain the rate-tvpe constitutive expressions of the nonlinearisotropic elastieity by using the Jaumann, Truesdell and Green-Naghdi stress rgterespectively,Through analysing the simple shear deformat...In this paper. we obtain the rate-tvpe constitutive expressions of the nonlinearisotropic elastieity by using the Jaumann, Truesdell and Green-Naghdi stress rgterespectively,Through analysing the simple shear deformation for Mooney-Rivlin material.three kinds of rate-type constitutive equations are verified to be equivalent to the original equation.Rate-type variational prineiples are also presented, and the Ritzmethod is used to obtain the numerical solution of a reetangular rubber membraneunder uniaxial streteh.展开更多
Surrounding rocks at different locations are generally subjected to different stress paths during the process of deep hard rock excavation.In this study,to reveal the mechanical parameters of deep surrounding rock und...Surrounding rocks at different locations are generally subjected to different stress paths during the process of deep hard rock excavation.In this study,to reveal the mechanical parameters of deep surrounding rock under different stress paths,a new cyclic loading and unloading test method for controlled true triaxial loading and unloading and principal stress direction interchange was proposed,and the evolution of mechanical parameters of Shuangjiangkou granite under different stress paths was studied,including the deformation modulus,elastic deformation increment ratios,fracture degree,cohesion and internal friction angle.Additionally,stress path coefficient was defined to characterize different stress paths,and the functional relationships among the stress path coefficient,rock fracture degree difference coefficient,cohesion and internal friction angle were obtained.The results show that during the true triaxial cyclic loading and unloading process,the deformation modulus and cohesion gradually decrease,while the internal friction angle gradually increases with increasing equivalent crack strain.The stress path coefficient is exponentially related to the rock fracture degree difference coefficient.As the stress path coefficient increases,the degrees of cohesion weakening and internal friction angle strengthening decrease linearly.During cyclic loading and unloading under true triaxial principal stress direction interchange,the direction of crack development changes,and the deformation modulus increases,while the cohesion and internal friction angle decrease slightly,indicating that the principal stress direction interchange has a strengthening effect on the surrounding rocks.Finally,the influences of the principal stress interchange direction on the stabilities of deep engineering excavation projects are discussed.展开更多
A three-dimensional finite element model was established for the milling of thin-walled parts. The physical model of the milling of the part was established using the AdvantEdge FEM software as the platform. The alumi...A three-dimensional finite element model was established for the milling of thin-walled parts. The physical model of the milling of the part was established using the AdvantEdge FEM software as the platform. The aluminum alloy impeller was designated as the object to be processed and the boundary conditions which met the actual machining were set. Through the solution, the physical quantities such as the three-way cutting force, the tool temperature, and the tool stress were obtained, and the calculation of the elastic deformation of the thin-walled blade of the free-form surface at the contact points between the tool and the workpiece was realized. The elastic deformation law of the thin-walled blade was then predicted. The results show that the maximum deviation between the predicted value and the actual measured machining value of the elastic deformation was 26.055 μm; the minimum deviation was 2.011 μm, with the average deviation being 10.154 μm. This shows that the prediction is in close agreement with the actual result.展开更多
Based on the elongated Kelvin obtained to investigate the tensile behavior Kelvin model＇s periodicity and symmetry in model, a simplified periodic structural cell is of anisotropic open-cell elastic foams due to the ...Based on the elongated Kelvin obtained to investigate the tensile behavior Kelvin model＇s periodicity and symmetry in model, a simplified periodic structural cell is of anisotropic open-cell elastic foams due to the whole space. The half-strut element and elastic deflection theory are used to analyze the tensile response as done in the previous studies. This study produces theoretical expressions for the tensile stress-strain curve in the rise and transverse directions. In addition, the theoretical results are examined with finite element simulation using an existing formula. The results indicate that the theoretical analysis agrees with the finite element simulation when the strain is not too high, and the present model is better. At the same time, the anisotropy ratio has a significant effect on the mechanical properties of foams. As the anisotropy ratio increases, the tensile stress is improved in the rising direction but drops in the transverse direction under the same strain.展开更多
Dynamics of domain walls(DWs) was studied in transparent thin orthoferrite samples with weak ferromagnetic ordering at subsonic and supersonic speeds.Direct measurements were made of flexural vibration amplitude in th...Dynamics of domain walls(DWs) was studied in transparent thin orthoferrite samples with weak ferromagnetic ordering at subsonic and supersonic speeds.Direct measurements were made of flexural vibration amplitude in the samples studied,which were induced by a solitary DW with periodic actions of a driving magnetic field.The values of the amplitude reached 7 nm at a resonance.The formation of magnetoelastic solitons was observed and their dynamics was studied at a resonance between an elastic and a spin subsystems.Solitons lag behind the DW at the moment when the DW surpasses the sound barrier and are ahead of it at the subsonic motion.展开更多
Composite wing static aeroelasticity was analyzed through a loosely coupled method and the effects on composite wing characteristics under different flight attitudes were presented. Structural analysis and aerodynamic...Composite wing static aeroelasticity was analyzed through a loosely coupled method and the effects on composite wing characteristics under different flight attitudes were presented. Structural analysis and aerodynamic analysis were carried out through finite element method (FEM) software NASTRAN and computational fluid dynamics (CFD) software FLUENT, respectively. Correlative data transfer and mesh regenerate procedure were applied to couple the results of computational structure dynamics (CSD) and CFD. After static aeroelasticity analysis under different flight attitudes, it can be seen that lift increases with the increase of flight speed and the incremental value enlarges gradually in both rigid and elastic wings. Lift presents a linear increment relationship with the increase of attack angle when the flight speed is 0.4Ma or 0.6Ma, but nonlinear increment in elastic wing when flight speed is 0.8Ma. On the effect of aeroelasticity, the maximum of deformation increases with the increase of flight speed and attack angle, and the incremental value decreases with the increase of flight speed while uniform with different attack angles. The results provide a reference for engineering applications.展开更多
The cold strip rolling process on a 4 h mill is studied by coupling the 3 dimensional plasticity deformation of the strip with the elastic deformation of the rolls. On the conditions of that the width to thickness ra...The cold strip rolling process on a 4 h mill is studied by coupling the 3 dimensional plasticity deformation of the strip with the elastic deformation of the rolls. On the conditions of that the width to thickness ratio of the strip is 660 and the exit strip shapes are respectively edge wave, centre wave and good, the computed results of the transverse distributions of the roll gap, the rolling pressure, the inter roll pressure, and the front and back tension agree with the experimental results well. The studing methods and the studied results are of great importance to forming shape theory and guiding the development of shape control technology.展开更多
Quantitative investigation on mechanical characteristics of cardiac myocytes has important physiological significance. Based on elastic substrate technique, this paper develops a set of algorithms for high-efficiency ...Quantitative investigation on mechanical characteristics of cardiac myocytes has important physiological significance. Based on elastic substrate technique, this paper develops a set of algorithms for high-efficiency cellular traction recovery. By applying a gradient-based digital image correlation method to track randomly distributed fluorescence microbeads on the deformed substrate induced by single cardiac myocyte, high-resolution substrate displacement field can readily be obtained. By using a numerical algorithm based on the integral Boussinesq solution, cell-substrate tractions are reconstructed in a stable and reliable manner. Finally, spatiotemporal dynamics of a single cardiac myocyte is investigated as it adheres to a polyacrylamide elastic substrate.展开更多
The equations for calculating the deformation of parallelogram type flexible guide, which is caused by the external force, are derived. The correctness of these equations is verified by comparison with other research ...The equations for calculating the deformation of parallelogram type flexible guide, which is caused by the external force, are derived. The correctness of these equations is verified by comparison with other research results and through the concrete design. These equations are applicable for flexible guides with any size.展开更多
文摘A compound varifocal lens based on electromagnetic drive technology is designed and fabricated, where the polydimethylsiloxane(PDMS) film acts as a driving component, while the PDMS biconvex lens and the plane-concave lens form a coaxial compound lens system. The plane-concave lens equipped with driving coils is installed directly above the PDMS lens surrounded by the annular magnet. When different currents are applied, the annular magnet moves up and down, driving the PDMS film to undergo elastic deformation, and then resulting in longitudinal movement of the PDMS lens. The position change of the PDMS lens changes the focal length of the compound lens system. To verify the feasibility and practicability of this design, a prototype of our compound lens system is fabricated in experiment. Our proposed compound lens shows that its zoom ability reaches 9.28 mm when the current ranges from -0.20 A to 0.21 A.
基金Projects (51002045, 10947105) supported by the National Natural Science Foundation of ChinaProject (2010B430016) supported by the Nature Science Research Project of Education Department of Henan Province, ChinaProject (2012IRTSTHN007) supported by Program for Innovative Research Team (in Science and Technology) in the University of Henan Province, China
文摘A classic hysteretic model, Preisach-Mayergoyz model （P-M model）, was used to calculate the nonlinear elastic deformation of magnesium （Mg） and cobalt （Co）. Mg and Co samples in cylinder shape were compressively tested by uniaxial test machine to obtain their stress—strain curves with hysteretic loops. The hysteretic loops do have two properties of P-M hysteretic systems： wiping out and congruency. It is proved that P-M model is applicable for the analysis of these two metals’ hysteresis. This model was applied on Mg at room temperature and Co at 300 ℃. By the P-M model, Co and Mg nonlinear elastic deformation can be calculated based on the stress history. The simulated stress—strain curves agree well with the experimental results. Therefore, the mechanical hysteresis of these two metals can be easily predicted by the classic P-M hysteretic model.
文摘The calculation error of the gauge-meter model will affect the gap setting precision and the self-learn precision of rolling force. The precision of the gauge-meter model is strongly influenced by plate width, working roll radius, backup roll radius, working roll crown, backup roll crown, and rolling force. The influence rules are hard to get by measuring. Taking a conventional 4-h plate mill as the research subject, these influences were transferred into the calculation of roll deflection and flattening deformation. To calculate these deformations, the theory of the influence function method was adopted. By modifying the traditional gauge-meter model, a novel model of the effect of roll elastic deformation on the gap setting was built by data fitting. By this model, it was convenient to analyze the variation caused by the rolling condition. Combining the elastic deformation model of rolls with the kiss-rolls method, a gauge-meter model was put forward for plate thickness prediction. The prediction precision of thickness was greatly improved by the new gauge- meter model.
基金United Arab Emirates University,Al Ain,UAE with Grant No.31S363-UPAR(4)2018.
文摘The buoyancy driven flow of a second-grade nanofluid in the presence of a binary chemical reaction is analyzed in the context of a model based on the balance equations for mass,species concentration,momentum and energy.The elastic properties of the considered fluid are taken into account.The two-dimensional slip flow of such non-Newtonian fluid over a porous flat material which is stretched vertically upwards is considered.The role played by the activation energy is accounted for through an exponent form modified Arrhenius function added to the Buongiorno model for the nanofluid concentration.The effects of thermal radiation are also examined.A similarity transformations is used to turn the problem based on partial differential equations into a system of ordinary differential equations.The resulting system is solved using a fourth order RK and shooting methods.The velocity profile,temperature profile,concentration profile,local skin friction,local Nusselt number and local Sherwood number are reported for several circumstances.The influence of the chemical reaction on the properties of the concentration and momentum boundary layers is critically discussed.
基金Sponsored by National Natural Science Foundation of China(50104004)
文摘The error of gaugemeter equation decreases the gap setting precision.The precision of gaugemeter equation is strongly influenced by plate width,work roll radius,backup roll radius,work roll crown,backup roll crown and rolling force.And these influences are hard to measure.All these factors are converted to roll deflection deformation and roll flattening deformation for calculation.In order to calculate the deformation,the theory of influence function method was adopted.By using simulation program,the influence of these factors on deformation was obtained.Then a simple model can be built.With this model,it is convenient to analyze the influence of different factors on gaugemeter equation.
基金financially supported by the National Natural Science Foundation of China(No.52175410)the Six Talent Peaks Project in Jiangsu Province(No.2019-XCL-113)+1 种基金Zhenjiang Science&Technology Program(No.GY2020001)the Project of Faculty of Agricultural Equipment of Jiangsu University(No.NZXB20200101)。
文摘In this work,the underlying mechanism responsible for the near-linear elastic deformation behavior of a dual-phase Ti-Nb alloy consisting of β and α'' phase with large recoverable strain was systematically elucidated.Based on in situ synchrotron X-ray diffraction(SXRD)analyses,it was found that besides intrinsic elastic deformation,a slight reversible β-α'' stress-induced martensitic(SIM)transformation,which proceeded in a consecutive mode under the retarding effect of micro-defects,took place during the near-linear elastic deformation.After unloading,a small amount of residual macroscopic strain remained in the specimen due to the incomplete reverse α''→β transformation on unloading.The high near-linear elastic deformability of the cold drawing(CD)Ti-Nb alloy has been revealed to be attributed to the coupling actions of intrinsic elasticity as well as the consecutive and reversible β-α'' SIM transformation.Our research may contribute to a new avenue for the design and development of novel dual-phase Ti-based alloys with desirable elastic deformability.
基金supported by the China Postdoctoral Science Foundation(Grant No.2019M662592)the National Key Research and Development Program of China(Grant No.2019YFA0706703)the National Natural Science Foundation of China(Grant Nos.51975443,51675394,51775211)。
文摘Precision prediction of machined surface roughness is challenging facing the robotic belt grinding of complex blade,since this process is accompanied by significant elastic deformation.The resulting poor prediction accuracy,to a great extent,is attributed to the existing prediction model which less considers the dynamics.In this paper,an improved scallop height model is developed to predict and assess the machined surface roughness by taking into account the elastic deformation and the varying curvature of blade,then robotic belt grinding experiments are carried out to evaluate the proposed model from the perspective of surface roughness.Finally factors that influence the scallop height are analyzed,and the suitable empirical equation of surface roughness is proposed to assess and predict the surface quality from the aspect of blade concave and convex surface by adopting the constant scallop height machining.
文摘This communication is devoted to analyze elastic deformation on electrically conducted viscoelastic fluid in the presence of viscous dissipation effects. Non-linear analysis is computed through exact solutions for velocity,temperature and concentration profiles. Special emphasis is provided for elastic deformation in the presence of magnetohydrodynamics effects. Concentration profile is discussed significantly in the presence constructive and destructive chemical reaction. Results are displayed through graphs and discussed for physical parameters that are used in present analysis. Notable findings include that temperature and thermal boundary layer thickness is an increasing function of Prandtl number and a decreasing function of elastic deformation. In addition, heat transfer rate is enhanced by increasing the conjugate parameter(γ) which measures the strength of surface heating.
基金the financial support by the National Natural Science Foundation of China(51371078,51671067)
文摘The room temperature brittleness has been a long standing problem in bulk metallic glasses realm.This has seriously limited the application potential of metallic glasses and their composites.The elastic deformation behaviors of metallic glass matrix composites are closely related to their plastic deformation states.The elastic deformation behaviors of Cu48-xZr48Al4Nbx（x=0,3at.%）metallic glass matrix composites（MGMCs）with different crystallization degrees were investigated using an in-situ digital image correlation（DIC）technique during tensile process.With decreasing crystallization degree,MGMC exhibits obvious elastic deformation ability and an increased tensile fracture strength.The notable tensile elasticity is attributed to the larger shear strain heterogeneity emerging on the surface of the sample.This finding has implications for the development of MGMCs with excellent tensile properties.
文摘Based on the new viewpoint of solid and gas interaction mechanics, gas leakage in a double deformable coal seam can be understood. That is, under the action of geophysical fields, the methane flow in a double deformable coal seam can be essentially considered to be compressible with time dependent and mixed permeation and diffusion through a pore cleat deformable heterogeneous and anisotropy medium. Based on this new viewpoint, a coupled mathematical model for coal seam deformation and gas leakage in a double coal seam was formulated and numerical simulations for gas emission from the coal seam are presented. It is found that coupled models might be closer to reality.
文摘A flew numerical method for constructing a pressure distribution to calculate surface elastic deformationcaused by normal contact pressure is developed in this paper. The pressure distribution over one of nonequidistantrectangles is fitted by an approximate tangent plane(ATP), which is formed by five pressure samples. Because thepressure distribution could be expressed as an one order linear polynomial, the iterative expression of elasticdeformation deduced by this method is simple, and the numerical accuracy is higher.
文摘In this paper. we obtain the rate-tvpe constitutive expressions of the nonlinearisotropic elastieity by using the Jaumann, Truesdell and Green-Naghdi stress rgterespectively,Through analysing the simple shear deformation for Mooney-Rivlin material.three kinds of rate-type constitutive equations are verified to be equivalent to the original equation.Rate-type variational prineiples are also presented, and the Ritzmethod is used to obtain the numerical solution of a reetangular rubber membraneunder uniaxial streteh.
基金the financial support from the National Natural Science Foundation of China(Grant Nos.51839003 and 42207221).
文摘Surrounding rocks at different locations are generally subjected to different stress paths during the process of deep hard rock excavation.In this study,to reveal the mechanical parameters of deep surrounding rock under different stress paths,a new cyclic loading and unloading test method for controlled true triaxial loading and unloading and principal stress direction interchange was proposed,and the evolution of mechanical parameters of Shuangjiangkou granite under different stress paths was studied,including the deformation modulus,elastic deformation increment ratios,fracture degree,cohesion and internal friction angle.Additionally,stress path coefficient was defined to characterize different stress paths,and the functional relationships among the stress path coefficient,rock fracture degree difference coefficient,cohesion and internal friction angle were obtained.The results show that during the true triaxial cyclic loading and unloading process,the deformation modulus and cohesion gradually decrease,while the internal friction angle gradually increases with increasing equivalent crack strain.The stress path coefficient is exponentially related to the rock fracture degree difference coefficient.As the stress path coefficient increases,the degrees of cohesion weakening and internal friction angle strengthening decrease linearly.During cyclic loading and unloading under true triaxial principal stress direction interchange,the direction of crack development changes,and the deformation modulus increases,while the cohesion and internal friction angle decrease slightly,indicating that the principal stress direction interchange has a strengthening effect on the surrounding rocks.Finally,the influences of the principal stress interchange direction on the stabilities of deep engineering excavation projects are discussed.
基金Project(U1530138)supported by the National Natural Science Foundation of ChinaProject(A1-8903-17-0103)supported by the Natural Science Foundation of Shanghai Municipal Education Commission,China
文摘A three-dimensional finite element model was established for the milling of thin-walled parts. The physical model of the milling of the part was established using the AdvantEdge FEM software as the platform. The aluminum alloy impeller was designated as the object to be processed and the boundary conditions which met the actual machining were set. Through the solution, the physical quantities such as the three-way cutting force, the tool temperature, and the tool stress were obtained, and the calculation of the elastic deformation of the thin-walled blade of the free-form surface at the contact points between the tool and the workpiece was realized. The elastic deformation law of the thin-walled blade was then predicted. The results show that the maximum deviation between the predicted value and the actual measured machining value of the elastic deformation was 26.055 μm; the minimum deviation was 2.011 μm, with the average deviation being 10.154 μm. This shows that the prediction is in close agreement with the actual result.
基金Project supported by the National Natural Science Foundation of China(Nos.11472025 and 11272030)
文摘Based on the elongated Kelvin obtained to investigate the tensile behavior Kelvin model＇s periodicity and symmetry in model, a simplified periodic structural cell is of anisotropic open-cell elastic foams due to the whole space. The half-strut element and elastic deflection theory are used to analyze the tensile response as done in the previous studies. This study produces theoretical expressions for the tensile stress-strain curve in the rise and transverse directions. In addition, the theoretical results are examined with finite element simulation using an existing formula. The results indicate that the theoretical analysis agrees with the finite element simulation when the strain is not too high, and the present model is better. At the same time, the anisotropy ratio has a significant effect on the mechanical properties of foams. As the anisotropy ratio increases, the tensile stress is improved in the rising direction but drops in the transverse direction under the same strain.
文摘Dynamics of domain walls(DWs) was studied in transparent thin orthoferrite samples with weak ferromagnetic ordering at subsonic and supersonic speeds.Direct measurements were made of flexural vibration amplitude in the samples studied,which were induced by a solitary DW with periodic actions of a driving magnetic field.The values of the amplitude reached 7 nm at a resonance.The formation of magnetoelastic solitons was observed and their dynamics was studied at a resonance between an elastic and a spin subsystems.Solitons lag behind the DW at the moment when the DW surpasses the sound barrier and are ahead of it at the subsonic motion.
基金Project(50905142) supported by the National Natural Science Foundation of ChinaProject(2009JQ1006) supported by the Natural Science Foundation of Shaanxi Province,China
文摘Composite wing static aeroelasticity was analyzed through a loosely coupled method and the effects on composite wing characteristics under different flight attitudes were presented. Structural analysis and aerodynamic analysis were carried out through finite element method (FEM) software NASTRAN and computational fluid dynamics (CFD) software FLUENT, respectively. Correlative data transfer and mesh regenerate procedure were applied to couple the results of computational structure dynamics (CSD) and CFD. After static aeroelasticity analysis under different flight attitudes, it can be seen that lift increases with the increase of flight speed and the incremental value enlarges gradually in both rigid and elastic wings. Lift presents a linear increment relationship with the increase of attack angle when the flight speed is 0.4Ma or 0.6Ma, but nonlinear increment in elastic wing when flight speed is 0.8Ma. On the effect of aeroelasticity, the maximum of deformation increases with the increase of flight speed and attack angle, and the incremental value decreases with the increase of flight speed while uniform with different attack angles. The results provide a reference for engineering applications.
文摘The cold strip rolling process on a 4 h mill is studied by coupling the 3 dimensional plasticity deformation of the strip with the elastic deformation of the rolls. On the conditions of that the width to thickness ratio of the strip is 660 and the exit strip shapes are respectively edge wave, centre wave and good, the computed results of the transverse distributions of the roll gap, the rolling pressure, the inter roll pressure, and the front and back tension agree with the experimental results well. The studing methods and the studied results are of great importance to forming shape theory and guiding the development of shape control technology.
基金supported by the National Basic Research Program (Grant No2007CB935602)the National Natural Science Foundation of China (Grant Nos90607004,10672005 and 10872008)
文摘Quantitative investigation on mechanical characteristics of cardiac myocytes has important physiological significance. Based on elastic substrate technique, this paper develops a set of algorithms for high-efficiency cellular traction recovery. By applying a gradient-based digital image correlation method to track randomly distributed fluorescence microbeads on the deformed substrate induced by single cardiac myocyte, high-resolution substrate displacement field can readily be obtained. By using a numerical algorithm based on the integral Boussinesq solution, cell-substrate tractions are reconstructed in a stable and reliable manner. Finally, spatiotemporal dynamics of a single cardiac myocyte is investigated as it adheres to a polyacrylamide elastic substrate.
文摘The equations for calculating the deformation of parallelogram type flexible guide, which is caused by the external force, are derived. The correctness of these equations is verified by comparison with other research results and through the concrete design. These equations are applicable for flexible guides with any size.
