This paper presents an investigation of well integrity during low-temperature CO_(2)injection using a model of thermo-poroelasticity with interface damage mechanics.The casing-cement and cement-formation interfaces ar...This paper presents an investigation of well integrity during low-temperature CO_(2)injection using a model of thermo-poroelasticity with interface damage mechanics.The casing-cement and cement-formation interfaces are described using cohesive interface elements and a bilinear traction-separation law.Verification testing is performed to establish the correct implementation of the coupled thermal,hydraulic,and mechanical equations.Simulation scenarios are developed to determine well interface damage initiation and development for intact wells and wells with an initial defect in the form of a 45°debonded azimuth.Each intact and defective well was simulated for30 days of CO_(2)injection at selected temperatures.Under the conditions considered,tensile radial stress developed at both the casing-cement and cement-formation interfaces.Hoop stress in the cement sheath remained compressive after 30 days but with reduced magnitude at the lower injection temperature,indicating greater risk of tensile stress and radial cracking as the injection temperature was reduced.Damage occurred in two of four scenarios considered,namely,the intact and defective wells at an injection temperature of 10℃,and was limited to the casing-cement interface,with no damage to the cement-formation interface.Inclusion of the pre-existing defect led to earlier damage initiation,at 2.75 days compared to 4 days,and produced a microannulus with over double the peak aperture at 0.077 mm compared to 0.037 mm.These findings emphasize the importance of accounting for initial defects and damage evolution when investigating the integrity of CO_(2)injection wells.展开更多
The interface between concrete and soil-rock mixture(SRM-concrete interface)under freeze-thaw cycles is very prone to creep damage,threatening the long-term stability of the superstructure in cold regions.However,ther...The interface between concrete and soil-rock mixture(SRM-concrete interface)under freeze-thaw cycles is very prone to creep damage,threatening the long-term stability of the superstructure in cold regions.However,there is no study concerning the characteristics of the nonlinear accelerated creep stage using the existing creep model in SRM-concrete interface.Therefore,shear creep tests were conducted to study the creep displacement and failure modes at the SRM-concrete interface under varying rock contents(15%-65%)and freeze-thaw cycles(0-20 iterations).A modified Burgers viscoelastic-plastic constitutive model is proposed to illustrate the creep failure characteristics of SRM-concrete interface induced by freeze-thaw cycles,which contains a hardening and loosening component.Results reveal a notable decrease in creep deformation correlating with increased rock content at SRM-concrete interface.Notably,the resistance of SRM-concrete interface to shear creep behavior peaks after five freeze-thaw cycles.This modified creep model accurately describes the nonlinear hardening and loosening creep behavior at the SRM-concrete interface,offering a substantial theoretical foundation for studying the longterm deformation and service life of superstructures in cold regions.展开更多
It is an important standard to judge the flood disaster in the basin whether the rainfall at the flood-inducing interface is reached.In this paper,the Xin'anjiang model,Topmodel model and SCS model were selected t...It is an important standard to judge the flood disaster in the basin whether the rainfall at the flood-inducing interface is reached.In this paper,the Xin'anjiang model,Topmodel model and SCS model were selected to calculate and compare the rainfall at the flood-inducing interface in the Zhanghe Reservoir basin in Hubei Province.The results showed that average relative error and average absolute error of Xin'anjiang model were-3.36%and-21.46×10^(5)m^(3),which were the minimum,followed by Topmodel model with 5.72%and 26.22×10^(5)m^(3),SCS model with 11.33%and 58.13×10^(5)m^(3).The minimum absolute error of the three hydrological models in calculating the rainfall at the critical interface was 3.26 mm,while the maximum was 49.24 mm.When the initial water level exceeded 120 m,the difference among the three models in calculating the rainfall at the critical interface became more and more obvious.When the reservoir water level was lower than 120 m,it mainly referred to the calculation results of Xin'anjiang model.When the reservoir water level was higher than 120 m,it mainly referred to the calculation results of Topmodel model.The research conclusion can provide reference for small and medium-sized basins selecting hydrological model to calculate the rainfall at the flood-inducing interface.展开更多
Building a model for a object through model composition is a interesting topics, this paper research the interface composit ion of models in the Zeigler’s modeling methodology DEVS.
This article introduces an element diffusion behavior model for a titanium/steel explosive clad plate characterized by a typical curved interface during the heat-treatment process. A series of heat-treatment experimen...This article introduces an element diffusion behavior model for a titanium/steel explosive clad plate characterized by a typical curved interface during the heat-treatment process. A series of heat-treatment experiments were conducted in the temperature range from 750℃ to 950℃, and the effects of heat-treatment parameters on the microstructural evolution and diffusion behavior were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction analysis, and electron-probe microanalysis. Carbon atoms within the steel matrix were observed to diffuse toward the titanium matrix and to aggregate at the bonding interface at 850℃ or lower; in contrast, when the temperature exceeded 850℃, the mutual diffusion of Ti and Fe occurred, along with the diffusion of C atoms, resulting in the for- marion of Ti-Fe intermetallics （Fe2Ti/FeTi）. The diffusion distances of C, Ti, and Fe atoms increased with increasing heating temperature and/or holding time. On the basis of this diffusion behavior, a novel diffusion model was proposed. This model considers the effects of various factors, including the curvature radius of the curved interface, the diffusion coefficient, the heating temperature, and the holding rime. The experimental results show good agreement with the calculated values. The proposed model could clearly provide a general prediction of the elements＇ diffusion at both straight and curved interfaces.展开更多
Due to the complexity of soil-structure interaction, simple constitutive models typically used for interface elements in general computer programs cannot satisfy the requirements of discontinuous deformation analysis ...Due to the complexity of soil-structure interaction, simple constitutive models typically used for interface elements in general computer programs cannot satisfy the requirements of discontinuous deformation analysis of structures that contain different interfaces. In order to simulate the strain-softening characteristics of interfaces, a nonlinear strain-softening interface constitutive model was incorporated into fast Lagrange analysis of continua in three dimensions （FLAC3D） through a user-defined program in the FISH environment. A numerical simulation of a direct shear test for geosynthetic interfaces was conducted to verify that the interface model was implemented correctly. Results of the numerical tests show good agreement with the results obtained from theoretical calculations, indicating that the model incorporated into FLAC3D can simulate the nonlinear strain-softening behavior of interfaces involving geosynthetic materials. The results confirmed the validity and reliability of the improved interface model. The procedure and method of implementing an interface constitutive model into a commercial computer program also provide a reference for implementation of a new interface constitutive model in FLAC3D.展开更多
Whether the particle will be trapped by the solid-liquid interface or not is dependent on its moving behavior ahead of the interface, so a mathematical model has been developed to investigate the movement of the parti...Whether the particle will be trapped by the solid-liquid interface or not is dependent on its moving behavior ahead of the interface, so a mathematical model has been developed to investigate the movement of the particle ahead of the solid-liquid interface. Based on the theory for the boundary layer, the fluid velocity field near the solid-liquid interface was obtained, and the trajectories of particles were calculated by the equations of motion for particles. In this model, the drag force, the added mass force, the buoyance force, the gravitational force, the Saffman force and the Basset history force are considered. The results show that the behavior of the particle ahead of the solid-liquid interface is affected by the physical property of the particle and fluid flow. And in the continuous casting process, if it moves in the stream directed upward or downward near vertical solid-liquid interface or in the horizontal flow under the solid-liquid interface, the particle with the diameter from 5 um to 60um can reach the solid-liquid interface. But if it moves in horizontal flow above the solid-liquid interface, only the particle with the diameter from 5 um to 10 um can reach the solid-liquid interface.展开更多
The behavior of soil-structure interface plays a major role in the definition of soil-structure interaction. In this paper a bi-potential surface elasto-plastic model for soil-structure interface is proposed in order ...The behavior of soil-structure interface plays a major role in the definition of soil-structure interaction. In this paper a bi-potential surface elasto-plastic model for soil-structure interface is proposed in order to describe the interface deformation behavior,including strain softening and normal dilatancy. The model is formulated in the framework of generalized potential theory,in which the soil-structure interface problem is regard as a two-dimensional mathematical problem in stress field,and plastic state equations are used to replace the traditional field surface. The relation curves of shear stress and tangential strain are fitted by a piecewise function composed by hyperbolic functions and hyperbolic secant functions,while the relation curves of normal strain and tangential strain are fitted by another piecewise function composed by quadratic functions and hyperbolic secant functions. The approach proposed has the advantage of deriving an elastoplastic constitutive matrix without postulating the plastic potential functions and yield surface. Moreover,the mathematical principle is clear,and the entire model parameters can be identified by experimental tests. Finally,the predictions of the model have been compared with experimental results obtained from simple shear tests under normal stresses,and results show the model is reasonable and practical.展开更多
Two modeling methods of the root insert for wind turbine blade are presented,i.e.,the local mesh optimization method(LMOM)and the global modeling method(GMM).Based on the optimized mesh of the local model for the meta...Two modeling methods of the root insert for wind turbine blade are presented,i.e.,the local mesh optimization method(LMOM)and the global modeling method(GMM).Based on the optimized mesh of the local model for the metal contact interface,LMOM is proposed to analyze the load path and stress distribution characteristics,while GMM is used to calculate and analyze the stress distribution characteristics of the resin layer established between the bushing and composite layers of root insert.To validate the GMM,a tension test is carried out.The result successfully shows that the shear strain expresses a similar strain distribution tendency with the GMM′s results.展开更多
Axial piston pumps have been widely used in aircraft hydraulic systems to supply the system with pressurized fluid. The continuous improvement of the aircraft performance has put forward the demand on aviation piston ...Axial piston pumps have been widely used in aircraft hydraulic systems to supply the system with pressurized fluid. The continuous improvement of the aircraft performance has put forward the demand on aviation piston pumps for high power density, safety, and reliability. The lubricating interfaces in axial piston machines are the key design issue that greatly determines the pump performance and service life. The cylinder block/valve plate interface is one of these critical lubricating interfaces and has received considerable attention from many researchers in the last half century. This study aims to review the state-of-the-art literature on the cylinder block/valve plate interface comprehensively and systematically. First, we introduce various theoretical models developed to investigate the lubrication behaviors of the interface and compare them in terms of their assumptions and limitations. Second, the experimental studies on the cylinder block/valve plate interface are presented comprehensively, where the involved test rigs are divided into three types according to their fidelity levels and measurement functionality. Third, we summarize some typical approaches of structure optimization, surface shaping, and surface strengthening, which help improve the load-carrying and anti-wear capacities of the interface under severe operating conditions. Finally, the challenges and future trends of the cylinder block/valve plate interface research are discussed briefly.展开更多
The shear characteristics of soil-structure interfaces with different roughness are studied systematically by us-ing the DRS-1 high normal stress and residual shear apparatus. The experimental results indicate that,un...The shear characteristics of soil-structure interfaces with different roughness are studied systematically by us-ing the DRS-1 high normal stress and residual shear apparatus. The experimental results indicate that,under a relatively high normal stress,normal stress and the coefficient of structural roughness are the most important factors affecting the mechanical interface characteristics. The relationship between shear stress and shear displacement of the soil-structure interface is a hyperbolic curve with high regression accuracy. Based on our experimental results,a nonlinear elastic con-stitutive model of the soil-structure interface under relatively high normal stress is established with a definite physical meaning for its parameters. The model can predict the strain hardening behavior of the soil during the shearing process. The results show an encouraging agreement with experimental data from direct shear tests.展开更多
The current work models a weak(soft) interface between two elastic materials as containing a periodic array of micro-crazes. The boundary conditions on the interfacial micro-crazes are formulated in terms of a system ...The current work models a weak(soft) interface between two elastic materials as containing a periodic array of micro-crazes. The boundary conditions on the interfacial micro-crazes are formulated in terms of a system of hypersingular integro-differential equations with unknown functions given by the displacement jumps across opposite faces of the micro-crazes. Once the displacement jumps are obtained by approximately solving the integro-differential equations, the effective stiffness of the micro-crazed interface can be readily computed. The effective stiffness is an important quantity needed for expressing the interfacial conditions in the spring-like macro-model of soft interfaces. Specific case studies are conducted to gain physical insights into how the effective stiffness of the interface may be influenced by the details of the interfacial micro-crazes.展开更多
Objectives To explore the relationship between CD80 expression on lymphocytes at the fetomaternal interface and the fertility characteristics in CBA/J×DBA/2 mice as a model of recurrent spontaneous abortion (RSA...Objectives To explore the relationship between CD80 expression on lymphocytes at the fetomaternal interface and the fertility characteristics in CBA/J×DBA/2 mice as a model of recurrent spontaneous abortion (RSA) and to investigate the effects of lymphocyte immunotherapy (LIT) on the level of CD80 expression. Materials & Methods The characteristics of fertility in CBA/J×DBA/2 mice were observed in a 120 day period and compared with four normal fertile groups. In another 15 pairs of CBA/J×DBA/2 breedings, resorption rate on day 13 of pregnancy were calculated and the proportion of CD80 + cells at the fetomaternal interface were determined by using two color flow cytometric analysis, mainly stained with CD80 FITC and CD45 PE. In order to determine the identity of CD80 + cells, the expression levels of CD3(T cell marker), DX5(NK cell marker), and MHC II(antigen presenting cell marker) were detected in this cell population. Furthermore, the resorption rate and the proportion of CD80 + cells among CBA/J×DBA/2 breedings with and without immunotherapy were also determined and compared with normal fertile controls. Results The characteristics of abortion in CBA/J×DBA/2 mice were recurrent abortion on about day 10 of gestation. The resorption rate in CBA/J×DBA/2 mice was significantly higher than that in BALB/c×DBA/2 mice (30.8%±16.6% vs. 7.7%±6.7%, P<0.01). Accordingly, the proportion of CD80 + cells evaluated at the fetomaternal interface in CBA/J×DBA/2 mice was also significantly higher (11.7% ±5.8% vs. 3.9%±1.8%, P<0.01). Resorption rate of CBA/J×DBA/2 mice underwent of LIT was significantly lower than that without LIT, and this decreased rate was correlated with decreased proportion of CD80 + cells. Conclusion In CBA/J×DBA/2 mice model, the characteristics of abortion seem to be peri implantation embryo resorption. A correlation between early embryonic waste and higher CD80 proportion at the fetomaternal interface suggests that CD80 + cells may be an important determinant in recurrent peri implantation abortion.展开更多
The microstructures of the Zn-27Al alloy after modification, solid-solution treatment, and natural aging were studied. It was clarified why the damping properties of Zn-27Al alloys, after treatment, had advanced most ...The microstructures of the Zn-27Al alloy after modification, solid-solution treatment, and natural aging were studied. It was clarified why the damping properties of Zn-27Al alloys, after treatment, had advanced most on the basis of analyzing the microstructures. Approximate expressions have been educed, which can be used to quantificationally work out the damping of the Zn-27Al alloy on the basis of the micro interface sliding model. By comparing the testing damping properties of the foundry Zn-27Al alloys and the Zn-27Al alloys after modification, solid solution, and natural aging, it was shown that the expressions were rational.展开更多
The Cr-plated coating inside a gun barrel can effectively improve the barrel’s erosion resistance and thus increase the service life.However,due to the cyclic thermal load caused by high-temperature gunpowder,micro-e...The Cr-plated coating inside a gun barrel can effectively improve the barrel’s erosion resistance and thus increase the service life.However,due to the cyclic thermal load caused by high-temperature gunpowder,micro-element damage tends to occur within the Cr coating/steel substrate interface,leading to a gradual deterioration in macro-mechanical properties for the material in the related region.In order to mimic this cyclic thermal load and,thereby,study the thermal erosion behavior of the Cr coating on the barrel’s inner wall,a laser emitter is utilized in the current study.With the help of in-situ tensile test and finite element simulation results,a shear stress distribution law of the Cr coating/steel substrate and a change law of the interface ultimate shear strength are identified.Studies have shown that the Cr coating/steel substrate interface’s ultimate shear strength has a significant weakening effect due to increasing temperature.In this study,the interfacial ultimate shear strength decreases from 2.57 GPa(no erosion)to 1.02 GPa(laser power is 160 W).The data from this experiment is employed to establish a Cr coating/steel substrate interface shear damage model.And this model is used to predict the flaking process of Cr coating by finite element method.The simulation results show that the increase of coating crack spacing and coating thickness will increase the service life of gun barrel.展开更多
Cyclic loads generated by environmental factors,such as winds,waves,and trains,will likely lead to performance degradation in pile foundations,resulting in issues like permanent displacement accumulation and bearing c...Cyclic loads generated by environmental factors,such as winds,waves,and trains,will likely lead to performance degradation in pile foundations,resulting in issues like permanent displacement accumulation and bearing capacity attenuation.This paper presents a semi-analytical solution for predicting the axial cyclic behavior of piles in sands.The solution relies on two enhanced nonlinear load-transfer models considering stress-strain hysteresis and cyclic degradation in the pile-soil interaction.Model parameters are calibrated through cyclic shear tests of the sand-steel interface and laboratory geotechnical testing of sands.A novel aspect involves the meticulous formulation of the shaft loadtransfer function using an interface constitutive model,which inherently inherits the interface model’s advantages,such as capturing hysteresis,hardening,degradation,and particle breakage.The semi-analytical solution is computed numerically using the matrix displacement method,and the calculated values are validated through model tests performed on non-displacement and displacement piles in sands.The results demonstrate that the predicted values show excellent agreement with the measured values for both the static and cyclic responses of piles in sands.The displacement pile response,including factors such as bearing capacity,mobilized shaft resistance,and convergence rate of permanent settlement,exhibit improvements compared to non-displacement piles attributed to the soil squeezing effect.This methodology presents an innovative analytical framework,allowing for integrating cyclic interface models into the theoretical investigation of pile responses.展开更多
Metallic flaky sendust particles are prepared for use as fillers in electromagnetic attenuation composites. We report the interface reflection model to divide the broad bandwidth into electromagnetic loss and quarter-...Metallic flaky sendust particles are prepared for use as fillers in electromagnetic attenuation composites. We report the interface reflection model to divide the broad bandwidth into electromagnetic loss and quarter-wavelength （λ/4） cancelation. Combining with the face reflection calculation, we identify the electromagnetic loss originated from skin effect, which is used to explain over half of the absorbed energy in high frequency band. Most impor- tantly, the unique electromagnetic loss cannot generate the reflection loss （RL） peak. Using the phase relation of face reflection, we show evidence that the λ/4 cancelation is vital to generate the RL peak. The calculated energy loss agrees well with the experimental data and lays the foundation for further research.展开更多
Considering both the effect of nonisothermal nature of the solid/liquid interface and the microscopic solvability theory (MicST), a further improved version of free dendritic growth model for pure materials was propos...Considering both the effect of nonisothermal nature of the solid/liquid interface and the microscopic solvability theory (MicST), a further improved version of free dendritic growth model for pure materials was proposed. Model comparison indicates that there is a higher temperature at the tip of dendrite predicted by the present model compared with the corresponding model with the isothermal solid/liquid interface assumption. This is attributed to the sidewise thermal diffusion, i.e. the gradient of temperature along the nonisothermal interface. Furthermore, it is indicated that the distinction between the stability criteria from MicST and marginal stability theory (MarST) is more significant with the increase of bath undercoolings. Model test also indicates that the present model can give an agreement with the available experimental data. It is finally concluded that the nonisothermal nature of the solid/liquid interface and the stability criterion from MicST should be taken into account in modeling free dendritic growth.展开更多
This paper proposes a new interface constitutive model for fully grouted rock-bolts and cable-bolts based on pull-out test results.A database was created combining published experimental data with in-house tests.By me...This paper proposes a new interface constitutive model for fully grouted rock-bolts and cable-bolts based on pull-out test results.A database was created combining published experimental data with in-house tests.By means of a comprehensive framework,a Coulomb-type failure criterion accounting for friction mobilization was defined.During the elastic phase,in which the interface joint is not yet created,the proposed model provides zero radial displacement,and once the interface joint is created,interface dilatancy is modeled using a non-associated plastic potential inspired from the behavior of rock joints.The results predicted by the proposed model are in good agreement with experimental results.The model has been implemented in a finite element method(FEM)code and numerical simulations have been performed at the elementary and the structural scales.The results obtained provide confidence in the ability of the new model to assist in the design and optimization of bolting patterns.展开更多
Seismic traveltime tomographic inversion has played an important role in detecting the internal structure of the solid earth. We use a set of blocks to approximate geologically complex media that cannot be well descri...Seismic traveltime tomographic inversion has played an important role in detecting the internal structure of the solid earth. We use a set of blocks to approximate geologically complex media that cannot be well described by layered models or cells. The geological body is described as an aggregate of arbitrarily shaped blocks,which are separated by triangulated interfaces. We can describe the media as homogenous or heterogeneous in each block. We define the velocities at the given rectangle grid points for each block,and the heterogeneous velocities in each block can be calculated by a linear interpolation algorithm. The parameters of the velocity grid positions are independent of the model parameterization,which is advantageous in the joint inversion of the velocities and the node depths of an interface. We implement a segmentally iterative ray tracer to calculate traveltimes in the 3D heterogeneous block models.The damped least squares method is employed in seismic traveltime inversion,which includes the partial derivatives of traveltime with respect to the depths of nodes in the triangulated interfaces and velocities defined in rectangular grids. The numerical tests indicate that the node depths of a triangulated interface and homogeneous velocity distributions can be well inverted in a stratified model.展开更多
基金UK Carbon Capture and Storage Research Community,Grant/Award Number:Flexible Funding Call(2023#20)。
文摘This paper presents an investigation of well integrity during low-temperature CO_(2)injection using a model of thermo-poroelasticity with interface damage mechanics.The casing-cement and cement-formation interfaces are described using cohesive interface elements and a bilinear traction-separation law.Verification testing is performed to establish the correct implementation of the coupled thermal,hydraulic,and mechanical equations.Simulation scenarios are developed to determine well interface damage initiation and development for intact wells and wells with an initial defect in the form of a 45°debonded azimuth.Each intact and defective well was simulated for30 days of CO_(2)injection at selected temperatures.Under the conditions considered,tensile radial stress developed at both the casing-cement and cement-formation interfaces.Hoop stress in the cement sheath remained compressive after 30 days but with reduced magnitude at the lower injection temperature,indicating greater risk of tensile stress and radial cracking as the injection temperature was reduced.Damage occurred in two of four scenarios considered,namely,the intact and defective wells at an injection temperature of 10℃,and was limited to the casing-cement interface,with no damage to the cement-formation interface.Inclusion of the pre-existing defect led to earlier damage initiation,at 2.75 days compared to 4 days,and produced a microannulus with over double the peak aperture at 0.077 mm compared to 0.037 mm.These findings emphasize the importance of accounting for initial defects and damage evolution when investigating the integrity of CO_(2)injection wells.
基金The National Natural Science Foundation of China(Grant No.42271144,Grant No.42071100)the Project of Shaanxi Province Qinchuangyuan"scientists&engineers"team construction(Grant No.2022KXJ-086)the Project of Application Fundamental Research of China Communications Construction(Grant No.2022-ZJKJ-PTJS07)。
文摘The interface between concrete and soil-rock mixture(SRM-concrete interface)under freeze-thaw cycles is very prone to creep damage,threatening the long-term stability of the superstructure in cold regions.However,there is no study concerning the characteristics of the nonlinear accelerated creep stage using the existing creep model in SRM-concrete interface.Therefore,shear creep tests were conducted to study the creep displacement and failure modes at the SRM-concrete interface under varying rock contents(15%-65%)and freeze-thaw cycles(0-20 iterations).A modified Burgers viscoelastic-plastic constitutive model is proposed to illustrate the creep failure characteristics of SRM-concrete interface induced by freeze-thaw cycles,which contains a hardening and loosening component.Results reveal a notable decrease in creep deformation correlating with increased rock content at SRM-concrete interface.Notably,the resistance of SRM-concrete interface to shear creep behavior peaks after five freeze-thaw cycles.This modified creep model accurately describes the nonlinear hardening and loosening creep behavior at the SRM-concrete interface,offering a substantial theoretical foundation for studying the longterm deformation and service life of superstructures in cold regions.
基金Supported by Open Project Fund of China Meteorological Administration Basin Heavy Rainfall Key Laboratory(2023BHR-Y26)Innovation Project Fund of Wuhan Metropolitan Area Meteorological Joint Science and Technology(WHCSQY202305)+1 种基金Innovation and Development Special Project of China Meteorological Administration(CXFZ2022J019)Project of Huanggang Meteorological Bureau's Scientific Research(2022Y02).
文摘It is an important standard to judge the flood disaster in the basin whether the rainfall at the flood-inducing interface is reached.In this paper,the Xin'anjiang model,Topmodel model and SCS model were selected to calculate and compare the rainfall at the flood-inducing interface in the Zhanghe Reservoir basin in Hubei Province.The results showed that average relative error and average absolute error of Xin'anjiang model were-3.36%and-21.46×10^(5)m^(3),which were the minimum,followed by Topmodel model with 5.72%and 26.22×10^(5)m^(3),SCS model with 11.33%and 58.13×10^(5)m^(3).The minimum absolute error of the three hydrological models in calculating the rainfall at the critical interface was 3.26 mm,while the maximum was 49.24 mm.When the initial water level exceeded 120 m,the difference among the three models in calculating the rainfall at the critical interface became more and more obvious.When the reservoir water level was lower than 120 m,it mainly referred to the calculation results of Xin'anjiang model.When the reservoir water level was higher than 120 m,it mainly referred to the calculation results of Topmodel model.The research conclusion can provide reference for small and medium-sized basins selecting hydrological model to calculate the rainfall at the flood-inducing interface.
文摘Building a model for a object through model composition is a interesting topics, this paper research the interface composit ion of models in the Zeigler’s modeling methodology DEVS.
文摘This article introduces an element diffusion behavior model for a titanium/steel explosive clad plate characterized by a typical curved interface during the heat-treatment process. A series of heat-treatment experiments were conducted in the temperature range from 750℃ to 950℃, and the effects of heat-treatment parameters on the microstructural evolution and diffusion behavior were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction analysis, and electron-probe microanalysis. Carbon atoms within the steel matrix were observed to diffuse toward the titanium matrix and to aggregate at the bonding interface at 850℃ or lower; in contrast, when the temperature exceeded 850℃, the mutual diffusion of Ti and Fe occurred, along with the diffusion of C atoms, resulting in the for- marion of Ti-Fe intermetallics （Fe2Ti/FeTi）. The diffusion distances of C, Ti, and Fe atoms increased with increasing heating temperature and/or holding time. On the basis of this diffusion behavior, a novel diffusion model was proposed. This model considers the effects of various factors, including the curvature radius of the curved interface, the diffusion coefficient, the heating temperature, and the holding rime. The experimental results show good agreement with the calculated values. The proposed model could clearly provide a general prediction of the elements＇ diffusion at both straight and curved interfaces.
基金supported by the National Natural Science Foundation of China (Grant No.51079047)
文摘Due to the complexity of soil-structure interaction, simple constitutive models typically used for interface elements in general computer programs cannot satisfy the requirements of discontinuous deformation analysis of structures that contain different interfaces. In order to simulate the strain-softening characteristics of interfaces, a nonlinear strain-softening interface constitutive model was incorporated into fast Lagrange analysis of continua in three dimensions （FLAC3D） through a user-defined program in the FISH environment. A numerical simulation of a direct shear test for geosynthetic interfaces was conducted to verify that the interface model was implemented correctly. Results of the numerical tests show good agreement with the results obtained from theoretical calculations, indicating that the model incorporated into FLAC3D can simulate the nonlinear strain-softening behavior of interfaces involving geosynthetic materials. The results confirmed the validity and reliability of the improved interface model. The procedure and method of implementing an interface constitutive model into a commercial computer program also provide a reference for implementation of a new interface constitutive model in FLAC3D.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 59734080 and 59504006)the Project of National Fundamental Research and Development of China (Grant No. G1998061510) and High-Tech Research and Development Project
文摘Whether the particle will be trapped by the solid-liquid interface or not is dependent on its moving behavior ahead of the interface, so a mathematical model has been developed to investigate the movement of the particle ahead of the solid-liquid interface. Based on the theory for the boundary layer, the fluid velocity field near the solid-liquid interface was obtained, and the trajectories of particles were calculated by the equations of motion for particles. In this model, the drag force, the added mass force, the buoyance force, the gravitational force, the Saffman force and the Basset history force are considered. The results show that the behavior of the particle ahead of the solid-liquid interface is affected by the physical property of the particle and fluid flow. And in the continuous casting process, if it moves in the stream directed upward or downward near vertical solid-liquid interface or in the horizontal flow under the solid-liquid interface, the particle with the diameter from 5 um to 60um can reach the solid-liquid interface. But if it moves in horizontal flow above the solid-liquid interface, only the particle with the diameter from 5 um to 10 um can reach the solid-liquid interface.
基金supported by the National Natural Science Foundation of ChinaYalona River Hydropower Development of Ertan Hydropower Development Company (No.50639050)
文摘The behavior of soil-structure interface plays a major role in the definition of soil-structure interaction. In this paper a bi-potential surface elasto-plastic model for soil-structure interface is proposed in order to describe the interface deformation behavior,including strain softening and normal dilatancy. The model is formulated in the framework of generalized potential theory,in which the soil-structure interface problem is regard as a two-dimensional mathematical problem in stress field,and plastic state equations are used to replace the traditional field surface. The relation curves of shear stress and tangential strain are fitted by a piecewise function composed by hyperbolic functions and hyperbolic secant functions,while the relation curves of normal strain and tangential strain are fitted by another piecewise function composed by quadratic functions and hyperbolic secant functions. The approach proposed has the advantage of deriving an elastoplastic constitutive matrix without postulating the plastic potential functions and yield surface. Moreover,the mathematical principle is clear,and the entire model parameters can be identified by experimental tests. Finally,the predictions of the model have been compared with experimental results obtained from simple shear tests under normal stresses,and results show the model is reasonable and practical.
基金supported jointly by the National Basic Research Program of China("973"Program)(No2014CB046200)the National Science Foundation of Jiangsu Province(No.BK2014059)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe National Natural Science Foundation of China(No.11172135)
文摘Two modeling methods of the root insert for wind turbine blade are presented,i.e.,the local mesh optimization method(LMOM)and the global modeling method(GMM).Based on the optimized mesh of the local model for the metal contact interface,LMOM is proposed to analyze the load path and stress distribution characteristics,while GMM is used to calculate and analyze the stress distribution characteristics of the resin layer established between the bushing and composite layers of root insert.To validate the GMM,a tension test is carried out.The result successfully shows that the shear strain expresses a similar strain distribution tendency with the GMM′s results.
基金supported by Chinese Civil Aircraft Project [No. MJ-2017-S49]China National Postdoctoral Program for Innovative Talents [No. BX20200210]China Postdoctoral Science Foundation [No. 2019M660086]。
文摘Axial piston pumps have been widely used in aircraft hydraulic systems to supply the system with pressurized fluid. The continuous improvement of the aircraft performance has put forward the demand on aviation piston pumps for high power density, safety, and reliability. The lubricating interfaces in axial piston machines are the key design issue that greatly determines the pump performance and service life. The cylinder block/valve plate interface is one of these critical lubricating interfaces and has received considerable attention from many researchers in the last half century. This study aims to review the state-of-the-art literature on the cylinder block/valve plate interface comprehensively and systematically. First, we introduce various theoretical models developed to investigate the lubrication behaviors of the interface and compare them in terms of their assumptions and limitations. Second, the experimental studies on the cylinder block/valve plate interface are presented comprehensively, where the involved test rigs are divided into three types according to their fidelity levels and measurement functionality. Third, we summarize some typical approaches of structure optimization, surface shaping, and surface strengthening, which help improve the load-carrying and anti-wear capacities of the interface under severe operating conditions. Finally, the challenges and future trends of the cylinder block/valve plate interface research are discussed briefly.
基金Projects 50534040 supported by the National Natural Science Foundation of China2002CB412704 by the Major State Basic Research and Development Program of China
文摘The shear characteristics of soil-structure interfaces with different roughness are studied systematically by us-ing the DRS-1 high normal stress and residual shear apparatus. The experimental results indicate that,under a relatively high normal stress,normal stress and the coefficient of structural roughness are the most important factors affecting the mechanical interface characteristics. The relationship between shear stress and shear displacement of the soil-structure interface is a hyperbolic curve with high regression accuracy. Based on our experimental results,a nonlinear elastic con-stitutive model of the soil-structure interface under relatively high normal stress is established with a definite physical meaning for its parameters. The model can predict the strain hardening behavior of the soil during the shearing process. The results show an encouraging agreement with experimental data from direct shear tests.
文摘The current work models a weak(soft) interface between two elastic materials as containing a periodic array of micro-crazes. The boundary conditions on the interfacial micro-crazes are formulated in terms of a system of hypersingular integro-differential equations with unknown functions given by the displacement jumps across opposite faces of the micro-crazes. Once the displacement jumps are obtained by approximately solving the integro-differential equations, the effective stiffness of the micro-crazed interface can be readily computed. The effective stiffness is an important quantity needed for expressing the interfacial conditions in the spring-like macro-model of soft interfaces. Specific case studies are conducted to gain physical insights into how the effective stiffness of the interface may be influenced by the details of the interfacial micro-crazes.
基金National Key Fundamental Research Plan(" 973") Project( G1 9990 50 43 0 3 ) ,China
文摘Objectives To explore the relationship between CD80 expression on lymphocytes at the fetomaternal interface and the fertility characteristics in CBA/J×DBA/2 mice as a model of recurrent spontaneous abortion (RSA) and to investigate the effects of lymphocyte immunotherapy (LIT) on the level of CD80 expression. Materials & Methods The characteristics of fertility in CBA/J×DBA/2 mice were observed in a 120 day period and compared with four normal fertile groups. In another 15 pairs of CBA/J×DBA/2 breedings, resorption rate on day 13 of pregnancy were calculated and the proportion of CD80 + cells at the fetomaternal interface were determined by using two color flow cytometric analysis, mainly stained with CD80 FITC and CD45 PE. In order to determine the identity of CD80 + cells, the expression levels of CD3(T cell marker), DX5(NK cell marker), and MHC II(antigen presenting cell marker) were detected in this cell population. Furthermore, the resorption rate and the proportion of CD80 + cells among CBA/J×DBA/2 breedings with and without immunotherapy were also determined and compared with normal fertile controls. Results The characteristics of abortion in CBA/J×DBA/2 mice were recurrent abortion on about day 10 of gestation. The resorption rate in CBA/J×DBA/2 mice was significantly higher than that in BALB/c×DBA/2 mice (30.8%±16.6% vs. 7.7%±6.7%, P<0.01). Accordingly, the proportion of CD80 + cells evaluated at the fetomaternal interface in CBA/J×DBA/2 mice was also significantly higher (11.7% ±5.8% vs. 3.9%±1.8%, P<0.01). Resorption rate of CBA/J×DBA/2 mice underwent of LIT was significantly lower than that without LIT, and this decreased rate was correlated with decreased proportion of CD80 + cells. Conclusion In CBA/J×DBA/2 mice model, the characteristics of abortion seem to be peri implantation embryo resorption. A correlation between early embryonic waste and higher CD80 proportion at the fetomaternal interface suggests that CD80 + cells may be an important determinant in recurrent peri implantation abortion.
文摘The microstructures of the Zn-27Al alloy after modification, solid-solution treatment, and natural aging were studied. It was clarified why the damping properties of Zn-27Al alloys, after treatment, had advanced most on the basis of analyzing the microstructures. Approximate expressions have been educed, which can be used to quantificationally work out the damping of the Zn-27Al alloy on the basis of the micro interface sliding model. By comparing the testing damping properties of the foundry Zn-27Al alloys and the Zn-27Al alloys after modification, solid solution, and natural aging, it was shown that the expressions were rational.
文摘The Cr-plated coating inside a gun barrel can effectively improve the barrel’s erosion resistance and thus increase the service life.However,due to the cyclic thermal load caused by high-temperature gunpowder,micro-element damage tends to occur within the Cr coating/steel substrate interface,leading to a gradual deterioration in macro-mechanical properties for the material in the related region.In order to mimic this cyclic thermal load and,thereby,study the thermal erosion behavior of the Cr coating on the barrel’s inner wall,a laser emitter is utilized in the current study.With the help of in-situ tensile test and finite element simulation results,a shear stress distribution law of the Cr coating/steel substrate and a change law of the interface ultimate shear strength are identified.Studies have shown that the Cr coating/steel substrate interface’s ultimate shear strength has a significant weakening effect due to increasing temperature.In this study,the interfacial ultimate shear strength decreases from 2.57 GPa(no erosion)to 1.02 GPa(laser power is 160 W).The data from this experiment is employed to establish a Cr coating/steel substrate interface shear damage model.And this model is used to predict the flaking process of Cr coating by finite element method.The simulation results show that the increase of coating crack spacing and coating thickness will increase the service life of gun barrel.
基金the financial support provided by the National Natural Science Foundation of China(Grant No.42272310).
文摘Cyclic loads generated by environmental factors,such as winds,waves,and trains,will likely lead to performance degradation in pile foundations,resulting in issues like permanent displacement accumulation and bearing capacity attenuation.This paper presents a semi-analytical solution for predicting the axial cyclic behavior of piles in sands.The solution relies on two enhanced nonlinear load-transfer models considering stress-strain hysteresis and cyclic degradation in the pile-soil interaction.Model parameters are calibrated through cyclic shear tests of the sand-steel interface and laboratory geotechnical testing of sands.A novel aspect involves the meticulous formulation of the shaft loadtransfer function using an interface constitutive model,which inherently inherits the interface model’s advantages,such as capturing hysteresis,hardening,degradation,and particle breakage.The semi-analytical solution is computed numerically using the matrix displacement method,and the calculated values are validated through model tests performed on non-displacement and displacement piles in sands.The results demonstrate that the predicted values show excellent agreement with the measured values for both the static and cyclic responses of piles in sands.The displacement pile response,including factors such as bearing capacity,mobilized shaft resistance,and convergence rate of permanent settlement,exhibit improvements compared to non-displacement piles attributed to the soil squeezing effect.This methodology presents an innovative analytical framework,allowing for integrating cyclic interface models into the theoretical investigation of pile responses.
基金Supported by the Fundamental Research Fund for the Central Universities under Grant No LZUJBKY-2015-121the National Natural Science Foundations of China under Grant Nos 11574122 and 51102124the National Science Foundation for Fostering Talents in Basic Research of the National Natural Science Foundation of China
文摘Metallic flaky sendust particles are prepared for use as fillers in electromagnetic attenuation composites. We report the interface reflection model to divide the broad bandwidth into electromagnetic loss and quarter-wavelength （λ/4） cancelation. Combining with the face reflection calculation, we identify the electromagnetic loss originated from skin effect, which is used to explain over half of the absorbed energy in high frequency band. Most impor- tantly, the unique electromagnetic loss cannot generate the reflection loss （RL） peak. Using the phase relation of face reflection, we show evidence that the λ/4 cancelation is vital to generate the RL peak. The calculated energy loss agrees well with the experimental data and lays the foundation for further research.
基金Project(51671075) supported by the National Natural Science Foundation of ChinaProject(E201446) supported by the Natural Science Foundation of Heilongjiang Province,China+1 种基金Project(SKLSP201606) supported by Fund of the State Key Laboratory of Solidification Processing in NWPU,ChinaProject(2016M590970) supported by China Postdoctoral Science Foundation
文摘Considering both the effect of nonisothermal nature of the solid/liquid interface and the microscopic solvability theory (MicST), a further improved version of free dendritic growth model for pure materials was proposed. Model comparison indicates that there is a higher temperature at the tip of dendrite predicted by the present model compared with the corresponding model with the isothermal solid/liquid interface assumption. This is attributed to the sidewise thermal diffusion, i.e. the gradient of temperature along the nonisothermal interface. Furthermore, it is indicated that the distinction between the stability criteria from MicST and marginal stability theory (MarST) is more significant with the increase of bath undercoolings. Model test also indicates that the present model can give an agreement with the available experimental data. It is finally concluded that the nonisothermal nature of the solid/liquid interface and the stability criterion from MicST should be taken into account in modeling free dendritic growth.
基金supported by the Research Fund for Coal and Steel(RFCS)in the context of the European project Advancing Mining Support Systems to Enhance the Control of Highly Stressed Ground(AMSSTED)。
文摘This paper proposes a new interface constitutive model for fully grouted rock-bolts and cable-bolts based on pull-out test results.A database was created combining published experimental data with in-house tests.By means of a comprehensive framework,a Coulomb-type failure criterion accounting for friction mobilization was defined.During the elastic phase,in which the interface joint is not yet created,the proposed model provides zero radial displacement,and once the interface joint is created,interface dilatancy is modeled using a non-associated plastic potential inspired from the behavior of rock joints.The results predicted by the proposed model are in good agreement with experimental results.The model has been implemented in a finite element method(FEM)code and numerical simulations have been performed at the elementary and the structural scales.The results obtained provide confidence in the ability of the new model to assist in the design and optimization of bolting patterns.
基金supported financially by the Ministry of Science and Technology of China(2011CB808904)the National Natural Science Foundation of China(Nos.41021063,41174075,41004034,41174043,and 41274090)
文摘Seismic traveltime tomographic inversion has played an important role in detecting the internal structure of the solid earth. We use a set of blocks to approximate geologically complex media that cannot be well described by layered models or cells. The geological body is described as an aggregate of arbitrarily shaped blocks,which are separated by triangulated interfaces. We can describe the media as homogenous or heterogeneous in each block. We define the velocities at the given rectangle grid points for each block,and the heterogeneous velocities in each block can be calculated by a linear interpolation algorithm. The parameters of the velocity grid positions are independent of the model parameterization,which is advantageous in the joint inversion of the velocities and the node depths of an interface. We implement a segmentally iterative ray tracer to calculate traveltimes in the 3D heterogeneous block models.The damped least squares method is employed in seismic traveltime inversion,which includes the partial derivatives of traveltime with respect to the depths of nodes in the triangulated interfaces and velocities defined in rectangular grids. The numerical tests indicate that the node depths of a triangulated interface and homogeneous velocity distributions can be well inverted in a stratified model.
