The anchor stress extent of a prestress anchor cable project has a direct relation with the project safety and performance. Prestressed tensioning method is a kind of nondestructive testing method, by which a reverse ...The anchor stress extent of a prestress anchor cable project has a direct relation with the project safety and performance. Prestressed tensioning method is a kind of nondestructive testing method, by which a reverse stretching load is applied on the external exposure section of anchor cable under construction or in service, and then the elongation variation of stress bars is measured to determine the anchor stress. We elaborated the theory and testing mechanism of prestressed tensioning method, and systematically studied key issues during the prestressed tensioning process of anchor cable by using physical model test, including the composition of tension stress-elongation curve, the variation of anchor stress, the compensation of locked anchor stress, and the judgment of anchor stress, and verified the theory feasibility of prestressed tensioning method. A case study on slope anchor cable of one highway project was conducted to further discuss on the test method, operation procedures and judgment of prestressed tensioning method on obtaining anchor stress, and then the test data of three situations were analyzed. The result provides a theoretical basis and technical base for the application of prestressed tensioning method to the evaluation of construction quality and operation conditions of anchor cable project.展开更多
Filament winding has emerged as the main process for carbon fiber reinforced plastic(CFRP) fabrication, and tension control plays a key role in enhancing the quality of the winding products. With the continuous improv...Filament winding has emerged as the main process for carbon fiber reinforced plastic(CFRP) fabrication, and tension control plays a key role in enhancing the quality of the winding products. With the continuous improvement of prod?uct quality and e ciency, the precision of the tension control system is constantly improving. In this paper, a novel tension control method is proposed, which can regulate the fiber tension and transport speed of the winding process by governing the outputs of three di erent driven rollers(the torque of the unwind roll, the torque of the magnetic powder brake roller, and the speed of the master speed roller) in three levels. The mechanical structures and dynamic models of the driven rollers and idle rollers are established by considering the time?varying features of the roller radius and inertia. Moreover, the influence of parameters and speed variation on fiber tension is investigated using the increment model. Subsequently, the control method is proposed by applying fiber tension in three levels accord?ing to the features of the three driven rollers. An adaptive fuzzy controller is designed for tuning the PID parameters online to control the speed of the master speed roller. Simulation is conducted for verifying the performance and sta?bility of the proposed tension control method by comparing with those of the conventional PID control method. The result reveals that the proposed method outperforms the conventional method. Finally, an experimental platform is constructed, and the proposed system is applied to a winding machine. The performance and stability of the tension control system are demonstrated via a series of experiments using carbon fiber under di erent reference speeds and tensions. This paper proposes a novel tension control method to regulate the fiber tension and transport speed.展开更多
The surface tension of molten tin was determined by a set of self-developed digital equipment with sessile drop method at oxygen partial pressure of 1.0×10 -6MPa under different temperatures, and the dependence...The surface tension of molten tin was determined by a set of self-developed digital equipment with sessile drop method at oxygen partial pressure of 1.0×10 -6MPa under different temperatures, and the dependence of surface tension of molten tin on temperature was also discussed. The emphasis was placed on the comparison of surface tension of the same molten tin sample measured by using different equipments with sessile drop method. Results of the comparison indicate that the measurement results with sessile drop method under the approximate experimental conditions are coincident, and the self-developed digital equipment for surface tension measurement has higher stability and accuracy. The relationships of surface tension of molten tin and its temperature coefficient with temperature and oxygen partial pressure were also elucidated from the thermodynamic equilibrium analysis.展开更多
Parasitic flows may occur in the numerical simulation of incompressible multiphase flow due to errors in the calculation of surface tension terms, specifically for the curvature and unit normal vector. An improved met...Parasitic flows may occur in the numerical simulation of incompressible multiphase flow due to errors in the calculation of surface tension terms, specifically for the curvature and unit normal vector. An improved method for calculating the surface tension based on the level set approach is proposed, in which the contribution of not only the center node but also the rest area of a control volume to the calculation of surface tension is considered in a balanced manner. The weighted integration method (WIM) is more consistent with the concept of a banded in- terface in the level set method. It is applied to the temporal evolution of a two-dimensional neutrally buoyant liquid drop and a buoyancy driven deformable bubble in an immiscible fluid for the validation of WIM. The results show that the parasitic flows are evidently suppressed by the weighted integration method. The weight factors for WIM in 3-D cases are also suggested.展开更多
Surface tension is one of important physical features of melt alloy. Many properties of melt alloy, such as graphite shape of cast iron and modified microstructure of aluminum alloy, can be evaluated by means of surfa...Surface tension is one of important physical features of melt alloy. Many properties of melt alloy, such as graphite shape of cast iron and modified microstructure of aluminum alloy, can be evaluated by means of surface tension. In order to evaluate and control the melt quality in-situ melting operation, the authors advanced a new method and developed an automatic device for fast measuring surface tension of melt alloy and applied it to the practice of rapid identifying graphite shape of cast iron. In this paper, the principle of fast measuring surface tension, the construction of the automatic measurement device and the examples of evaluating graphite shape of cast iron based on the new method and device are discussed.展开更多
In this paper a method has been proposed for the calculation of cohesive work and thus sur-face tension of liquids by the Monte Carlo computer simulation method with the use of Kihara po-tential. The surface tension v...In this paper a method has been proposed for the calculation of cohesive work and thus sur-face tension of liquids by the Monte Carlo computer simulation method with the use of Kihara po-tential. The surface tension values calculated for liquid argon, oxygen and nitrogen are in fairagreement with the experimental data.展开更多
This paper aims to present the critical top tension for static equilibrium configurations of a steel catenary riser（SCR） by using the finite element method. The critical top tension is the minimum top tension that c...This paper aims to present the critical top tension for static equilibrium configurations of a steel catenary riser（SCR） by using the finite element method. The critical top tension is the minimum top tension that can maintain the equilibrium of the SCR. If the top tension is smaller than the critical value, the equilibrium of the SCR does not exist. If the top tension is larger than the critical value, there are two possible equilibrium configurations. These two configurations exhibit the nonlinear large displacement. The configuration with the smaller displacement is stable, while the one with larger displacement is unstable. The numerical results show that the increases in the riser＇s vertical distances, horizontal offsets, riser＇s weights, internal flow velocities, and current velocities increase the critical top tensions of the SCR. In addition, the parametric studies are also performed in order to investigate the limit states for the analysis and design of the SCR.展开更多
This paper presents a numerical analysis of the dynamic transient behaviors of undersea cables.In this numerical study,the governing equations based on Euler-Bernoulli beam theory are adopted,and they can satisfy many...This paper presents a numerical analysis of the dynamic transient behaviors of undersea cables.In this numerical study,the governing equations based on Euler-Bernoulli beam theory are adopted,and they can satisfy many applications no matter what the magnitude of the cable tension is.The nonlinear coupled equations are solved by a popular central finite difference method,and the numerical results of transient behaviors are presented when several kinds of surrounding conditions,such as different towing speeds of surface vessel,different currents and waves with various frequencies and amplitudes,are exerted.Then a detailed comparison of the results,including the upper end tension and cable shape in time-domain,is made under the above external excitations,and finally the possible reasons for these are further explained.展开更多
Surface tension of molten Ni-(Cr,Co,W) alloys was measured at the temperature of 1 773-1 873 K in an Ar+3%H2 atmosphere using an improved sessile drop method.The segregation of Cr,Co and W in alloy was calculated and ...Surface tension of molten Ni-(Cr,Co,W) alloys was measured at the temperature of 1 773-1 873 K in an Ar+3%H2 atmosphere using an improved sessile drop method.The segregation of Cr,Co and W in alloy was calculated and analyzed using Butler's equation.The results show a good agreement between measured and calculated data.The surface tension of molten Ni-(Cr,Co,W) alloys decreases with increasing temperature.In Ni-(Cr,Co,W) alloys,the element with lower surface tension tends to segregate on the surface of molten alloy while that with higher surface tension tends to segregate inside of the molten alloy.The larger the differences in surface tension,atom radius and electron configuration between solvent and solute are,the more significant the segregation is.As a result,Ni segregates onto the surface and Co and W segregate inside the alloys.展开更多
This work aims at comparing surface tension models in VOF(Volume of Fluid) modeling and investigating the effects of gas distributor and gas velocity. Hydrodynamics of a continuous chain of bubbles inside a bubble col...This work aims at comparing surface tension models in VOF(Volume of Fluid) modeling and investigating the effects of gas distributor and gas velocity. Hydrodynamics of a continuous chain of bubbles inside a bubble column reactor was simulated. The grid independence study was first conducted and a grid size of 1.0 mm was adopted in order to minimize the computing time without compromising the accuracy of the results. The predictions were validated by comparing the experimental studies reported in the literature. It was found that all surface tension models can describe the bubble rise and bubble plume in a column with slight deviations.展开更多
This paper presents a numerical investigation into the dynamics of marine cables which are extensively used in offshore industry. In this numerical study, the Euler-Bernoulli beam model is adopted to develop the gover...This paper presents a numerical investigation into the dynamics of marine cables which are extensively used in offshore industry. In this numerical study, the Euler-Bernoulli beam model is adopted to develop the governing equations of the cable. Bending stiffness is considered to cope with the low tension problem in local area of towing cable, and thus a more accurate solution with the consideration of the axial elongation can be given.The derived strongly-coupled and nonlinear governing equations are solved by a second-order accurate, implicit,and large time step stable central finite difference method. The quadratically convergent Newton-Raphson iteration method is applied to solving the discrete nonlinear algebraic equations. Then a towed array sonar system(TASS)problem is studied. The numerical solutions agree reasonably well with the experimental data and the simulated results of the references. The specified program of the present paper shows great robustness with high efficiency.展开更多
The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitut...The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitutive theory([1]) and B-L planar anisotropy yield criterion([2]). Simulated results are compared with experimental ones. Very good consistence is obtained between numerical and experimental results. The relationship between the anisotropy coefficient R and the shear band angle theta is found.展开更多
Surface tension of molten Ni and Ni-Co (5 and 10 mass fraction) alloys was measured at the temperature range of 1773-1873 K using an improved sessile drop method with an alumina substrate in an Ar+3%H2 atmosphere. The...Surface tension of molten Ni and Ni-Co (5 and 10 mass fraction) alloys was measured at the temperature range of 1773-1873 K using an improved sessile drop method with an alumina substrate in an Ar+3%H2 atmosphere. The error of the data obtained was analyzed. The surface tension of molten Ni and Ni-Co (5 and 10 mass fraction) alloys decreases with increasing temperature. The influence of Co on the surface tension of Ni-Co alloys is little in the studied Co concentration range.展开更多
In this study, we investigate the pseudopotential multiphase model of lattice Boltzmann method（LBM） and incorporate a surface tension term to implement the particle interaction force. By using the Carnahan–Starling...In this study, we investigate the pseudopotential multiphase model of lattice Boltzmann method（LBM） and incorporate a surface tension term to implement the particle interaction force. By using the Carnahan–Starling（CS） equation of state（EOS） with a proper critical pressure–density ratio, a density ratio over 160000 is obtained with satisfactory numerical stability. The added surface tension term offers a flexible choice to adjust the surface tension strength. Numerical tests of the Laplace rule are conducted, proving that smaller spurious velocity and better numerical stability can be acquired as the surface tension becomes stronger. Moreover, by wall adhesion and heterogeneous cavitation tests, the surface tension term shows its practical application in dealing with problems in which the surface tension plays an important role.展开更多
Stress Joint （SJ） plays a key role in the Top Tensioned Riser （TTR） system for deep water engineering. A preliminary design method of tapered SJ is proposed in the paper, which could help designers obtain accurate...Stress Joint （SJ） plays a key role in the Top Tensioned Riser （TTR） system for deep water engineering. A preliminary design method of tapered SJ is proposed in the paper, which could help designers obtain accurate design data. After a further sensitive analysis is carried out, the related parameters choice and control methods are recommended in the engineering practice. By taking the extreme environment conditions into consideration, the effects of bending stress reduction and curve control are analyzed, and the 3-D FE models are established by ABQOUS for numerical evaluation to verify the correctness of design results. At last, dynamic analysis and fatigue analysis, based on actual project, are carried out with designed stress joint. The analysis results prove the feasibility and guidance of this method in the practical engineering applications.展开更多
In this paper we aimed to determine the surface tension of traditional Chinese medicine (TCM) tablet and tried to provide a key reference parameter to control tablet film coating quality. Using contact angle tester, t...In this paper we aimed to determine the surface tension of traditional Chinese medicine (TCM) tablet and tried to provide a key reference parameter to control tablet film coating quality. Using contact angle tester, the Chinese medicine tablet, a famous Fufang Danshen tablet CP as a model example, was determined by Zisman critical surface tension method. Our study showed that the critical surface tension of Fufang Danshen tablet CP was determined to be 18.00 dyne/cm. The Zisman method, hence, can determine successfully the critical surface tension of Chinese medicine tablet and will become an effective manner to control tablet film coating quality.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
Different material properties leads to different metal fracture behaviors. Even if the powder material is composed of plastic metal, the fracture still does not show macroscopic plastic deformation characteristics if ...Different material properties leads to different metal fracture behaviors. Even if the powder material is composed of plastic metal, the fracture still does not show macroscopic plastic deformation characteristics if the material contains a large number of voids. Eight node isoparametric elastic plastic finite element method was used to simulate the tensile process of sintered powder material. By setting a number of voids in the analyzed metal cuboid, the initial density was taken into consideration. The material properties of the three dimensional solid for the tensile simulation were defined with reference to the known pure iron material parameters. The load displacement curves during elongation were obtained with a universal testing machine, and then the simulated curves were compared with the experimental results. The factors that cause the stress concentration and strength decrease were analyzed according to the simulated equivalent von Mises stress distribution.展开更多
Wind stress impacts on ocean relatively high waves can be perfectly illustrated by a recurrent phenomenon in the Sahara desert. Indeed, on this area where the surface wind can blow without encountering major obstacle ...Wind stress impacts on ocean relatively high waves can be perfectly illustrated by a recurrent phenomenon in the Sahara desert. Indeed, on this area where the surface wind can blow without encountering major obstacle out of the sand dunes, these main targets are gradually eroded and displaced by the wind on dozens of meters. This experience highlights the action of wind on granular targets (clusters of sand or water slides) and motivates studies similar to ours, where we want to simulate impact of wind stress and breaking on the spatio-temporal evolution of the envelope of ocean relatively high waves: Impact which can inappropriately deflect the waves on ships, oil platforms or coastal infrastructures. Euler and Navier-Stokes equations allow a mathematical formulation of the gravity wave motion (ocean waves are considered in our work as a system of water particles which are held together by low surface tension) and wind acts on targets through friction forces or stress. Michel Talon stationary phase method is used to numerically solve the equations that model the impact of wind on a stationary Gaussian.展开更多
The interfacial tension between FeO-CaO-SiO_2-MgO system slag and Cu-Fe-S system matte was determinated by the X-ray radiograph sessile drop method.The effects of FeO/SiO_2 ratio in the slag,contents of CaO,FeO,ZnO an...The interfacial tension between FeO-CaO-SiO_2-MgO system slag and Cu-Fe-S system matte was determinated by the X-ray radiograph sessile drop method.The effects of FeO/SiO_2 ratio in the slag,contents of CaO,FeO,ZnO and CaF_2 in the slag on interracial tension and the relation of inter facial tension with the grade of matte and temperature have been studied.The floatation coefficient and film coefficient of slag-matte system has been calculated and the mechanism of the transition of iron and oxygen from slag to matte has also been discussed.展开更多
基金Funded by the Science and Technolog Program of Ministry of Transport of P.R.China(No.2012318352100)
文摘The anchor stress extent of a prestress anchor cable project has a direct relation with the project safety and performance. Prestressed tensioning method is a kind of nondestructive testing method, by which a reverse stretching load is applied on the external exposure section of anchor cable under construction or in service, and then the elongation variation of stress bars is measured to determine the anchor stress. We elaborated the theory and testing mechanism of prestressed tensioning method, and systematically studied key issues during the prestressed tensioning process of anchor cable by using physical model test, including the composition of tension stress-elongation curve, the variation of anchor stress, the compensation of locked anchor stress, and the judgment of anchor stress, and verified the theory feasibility of prestressed tensioning method. A case study on slope anchor cable of one highway project was conducted to further discuss on the test method, operation procedures and judgment of prestressed tensioning method on obtaining anchor stress, and then the test data of three situations were analyzed. The result provides a theoretical basis and technical base for the application of prestressed tensioning method to the evaluation of construction quality and operation conditions of anchor cable project.
基金Supported by National Natural Science Foundation of China(Grant No.51575018)
文摘Filament winding has emerged as the main process for carbon fiber reinforced plastic(CFRP) fabrication, and tension control plays a key role in enhancing the quality of the winding products. With the continuous improvement of prod?uct quality and e ciency, the precision of the tension control system is constantly improving. In this paper, a novel tension control method is proposed, which can regulate the fiber tension and transport speed of the winding process by governing the outputs of three di erent driven rollers(the torque of the unwind roll, the torque of the magnetic powder brake roller, and the speed of the master speed roller) in three levels. The mechanical structures and dynamic models of the driven rollers and idle rollers are established by considering the time?varying features of the roller radius and inertia. Moreover, the influence of parameters and speed variation on fiber tension is investigated using the increment model. Subsequently, the control method is proposed by applying fiber tension in three levels accord?ing to the features of the three driven rollers. An adaptive fuzzy controller is designed for tuning the PID parameters online to control the speed of the master speed roller. Simulation is conducted for verifying the performance and sta?bility of the proposed tension control method by comparing with those of the conventional PID control method. The result reveals that the proposed method outperforms the conventional method. Finally, an experimental platform is constructed, and the proposed system is applied to a winding machine. The performance and stability of the tension control system are demonstrated via a series of experiments using carbon fiber under di erent reference speeds and tensions. This paper proposes a novel tension control method to regulate the fiber tension and transport speed.
文摘The surface tension of molten tin was determined by a set of self-developed digital equipment with sessile drop method at oxygen partial pressure of 1.0×10 -6MPa under different temperatures, and the dependence of surface tension of molten tin on temperature was also discussed. The emphasis was placed on the comparison of surface tension of the same molten tin sample measured by using different equipments with sessile drop method. Results of the comparison indicate that the measurement results with sessile drop method under the approximate experimental conditions are coincident, and the self-developed digital equipment for surface tension measurement has higher stability and accuracy. The relationships of surface tension of molten tin and its temperature coefficient with temperature and oxygen partial pressure were also elucidated from the thermodynamic equilibrium analysis.
基金the National Natural Science Foundation of China (No.20490206) the Special Funds for Major State BasicResearch Program of China (973 Program, 2004CB217604).
文摘Parasitic flows may occur in the numerical simulation of incompressible multiphase flow due to errors in the calculation of surface tension terms, specifically for the curvature and unit normal vector. An improved method for calculating the surface tension based on the level set approach is proposed, in which the contribution of not only the center node but also the rest area of a control volume to the calculation of surface tension is considered in a balanced manner. The weighted integration method (WIM) is more consistent with the concept of a banded in- terface in the level set method. It is applied to the temporal evolution of a two-dimensional neutrally buoyant liquid drop and a buoyancy driven deformable bubble in an immiscible fluid for the validation of WIM. The results show that the parasitic flows are evidently suppressed by the weighted integration method. The weight factors for WIM in 3-D cases are also suggested.
文摘Surface tension is one of important physical features of melt alloy. Many properties of melt alloy, such as graphite shape of cast iron and modified microstructure of aluminum alloy, can be evaluated by means of surface tension. In order to evaluate and control the melt quality in-situ melting operation, the authors advanced a new method and developed an automatic device for fast measuring surface tension of melt alloy and applied it to the practice of rapid identifying graphite shape of cast iron. In this paper, the principle of fast measuring surface tension, the construction of the automatic measurement device and the examples of evaluating graphite shape of cast iron based on the new method and device are discussed.
文摘In this paper a method has been proposed for the calculation of cohesive work and thus sur-face tension of liquids by the Monte Carlo computer simulation method with the use of Kihara po-tential. The surface tension values calculated for liquid argon, oxygen and nitrogen are in fairagreement with the experimental data.
基金supported by the Thailand Research Fund(TRF)through the Royal Golden Jubilee Ph.D.Program(Grant No.PHD/0112/2553)the National Research University(NRU)initiative
文摘This paper aims to present the critical top tension for static equilibrium configurations of a steel catenary riser（SCR） by using the finite element method. The critical top tension is the minimum top tension that can maintain the equilibrium of the SCR. If the top tension is smaller than the critical value, the equilibrium of the SCR does not exist. If the top tension is larger than the critical value, there are two possible equilibrium configurations. These two configurations exhibit the nonlinear large displacement. The configuration with the smaller displacement is stable, while the one with larger displacement is unstable. The numerical results show that the increases in the riser＇s vertical distances, horizontal offsets, riser＇s weights, internal flow velocities, and current velocities increase the critical top tensions of the SCR. In addition, the parametric studies are also performed in order to investigate the limit states for the analysis and design of the SCR.
基金the National High Technology Research and Development Program (863) of China(No. 2008AA092301-1)the National Natural Science Foundation of China(No. 50909061)the Ph.D. Programs Foundation of Ministry of Education of China(No. 20070248103)
文摘This paper presents a numerical analysis of the dynamic transient behaviors of undersea cables.In this numerical study,the governing equations based on Euler-Bernoulli beam theory are adopted,and they can satisfy many applications no matter what the magnitude of the cable tension is.The nonlinear coupled equations are solved by a popular central finite difference method,and the numerical results of transient behaviors are presented when several kinds of surrounding conditions,such as different towing speeds of surface vessel,different currents and waves with various frequencies and amplitudes,are exerted.Then a detailed comparison of the results,including the upper end tension and cable shape in time-domain,is made under the above external excitations,and finally the possible reasons for these are further explained.
基金Project(2004527) supported by Scientific Research Foundation for the Returned Overseas Chinese ScholarsProject(200594) supported by the Chongqing Bureau of Personal, China+2 种基金Project(KJ070603) supported by the Municipal Education Commission of Chongqing, ChinaProject(2003ZD31) supported by Chongqing Institute of Technology, ChinaProject(CSTC2005BA4016-1) supported by Chongqing Science and Technology Commission,China
文摘Surface tension of molten Ni-(Cr,Co,W) alloys was measured at the temperature of 1 773-1 873 K in an Ar+3%H2 atmosphere using an improved sessile drop method.The segregation of Cr,Co and W in alloy was calculated and analyzed using Butler's equation.The results show a good agreement between measured and calculated data.The surface tension of molten Ni-(Cr,Co,W) alloys decreases with increasing temperature.In Ni-(Cr,Co,W) alloys,the element with lower surface tension tends to segregate on the surface of molten alloy while that with higher surface tension tends to segregate inside of the molten alloy.The larger the differences in surface tension,atom radius and electron configuration between solvent and solute are,the more significant the segregation is.As a result,Ni segregates onto the surface and Co and W segregate inside the alloys.
基金Supported by the National Ministry of Science and Technology of China(2017YFB0602401)the National Natural Science Foundation of China(21776173,91834303,U1862201,21625603)the Program of Shanghai Subject Chief Scientists(18XD1402000).
文摘This work aims at comparing surface tension models in VOF(Volume of Fluid) modeling and investigating the effects of gas distributor and gas velocity. Hydrodynamics of a continuous chain of bubbles inside a bubble column reactor was simulated. The grid independence study was first conducted and a grid size of 1.0 mm was adopted in order to minimize the computing time without compromising the accuracy of the results. The predictions were validated by comparing the experimental studies reported in the literature. It was found that all surface tension models can describe the bubble rise and bubble plume in a column with slight deviations.
基金the National Science and Technology Major Project(No.2011ZX05027-004)the National Natural Science Foundation of China(No.51279107)
文摘This paper presents a numerical investigation into the dynamics of marine cables which are extensively used in offshore industry. In this numerical study, the Euler-Bernoulli beam model is adopted to develop the governing equations of the cable. Bending stiffness is considered to cope with the low tension problem in local area of towing cable, and thus a more accurate solution with the consideration of the axial elongation can be given.The derived strongly-coupled and nonlinear governing equations are solved by a second-order accurate, implicit,and large time step stable central finite difference method. The quadratically convergent Newton-Raphson iteration method is applied to solving the discrete nonlinear algebraic equations. Then a towed array sonar system(TASS)problem is studied. The numerical solutions agree reasonably well with the experimental data and the simulated results of the references. The specified program of the present paper shows great robustness with high efficiency.
基金The project supported by the National Natural Science Foundation of China and the Excellent Youth Teacher Foundation of the State Education Commission of China
文摘The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitutive theory([1]) and B-L planar anisotropy yield criterion([2]). Simulated results are compared with experimental ones. Very good consistence is obtained between numerical and experimental results. The relationship between the anisotropy coefficient R and the shear band angle theta is found.
文摘Surface tension of molten Ni and Ni-Co (5 and 10 mass fraction) alloys was measured at the temperature range of 1773-1873 K using an improved sessile drop method with an alumina substrate in an Ar+3%H2 atmosphere. The error of the data obtained was analyzed. The surface tension of molten Ni and Ni-Co (5 and 10 mass fraction) alloys decreases with increasing temperature. The influence of Co on the surface tension of Ni-Co alloys is little in the studied Co concentration range.
基金Project supported by the National Nature Science Foundation of China(Grant No.51109178)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20116102120009)
文摘In this study, we investigate the pseudopotential multiphase model of lattice Boltzmann method（LBM） and incorporate a surface tension term to implement the particle interaction force. By using the Carnahan–Starling（CS） equation of state（EOS） with a proper critical pressure–density ratio, a density ratio over 160000 is obtained with satisfactory numerical stability. The added surface tension term offers a flexible choice to adjust the surface tension strength. Numerical tests of the Laplace rule are conducted, proving that smaller spurious velocity and better numerical stability can be acquired as the surface tension becomes stronger. Moreover, by wall adhesion and heterogeneous cavitation tests, the surface tension term shows its practical application in dealing with problems in which the surface tension plays an important role.
基金supported by the National High Technology Research and Development Program of China (863 Program,Grant No. 2008AA09A105-04)
文摘Stress Joint （SJ） plays a key role in the Top Tensioned Riser （TTR） system for deep water engineering. A preliminary design method of tapered SJ is proposed in the paper, which could help designers obtain accurate design data. After a further sensitive analysis is carried out, the related parameters choice and control methods are recommended in the engineering practice. By taking the extreme environment conditions into consideration, the effects of bending stress reduction and curve control are analyzed, and the 3-D FE models are established by ABQOUS for numerical evaluation to verify the correctness of design results. At last, dynamic analysis and fatigue analysis, based on actual project, are carried out with designed stress joint. The analysis results prove the feasibility and guidance of this method in the practical engineering applications.
文摘In this paper we aimed to determine the surface tension of traditional Chinese medicine (TCM) tablet and tried to provide a key reference parameter to control tablet film coating quality. Using contact angle tester, the Chinese medicine tablet, a famous Fufang Danshen tablet CP as a model example, was determined by Zisman critical surface tension method. Our study showed that the critical surface tension of Fufang Danshen tablet CP was determined to be 18.00 dyne/cm. The Zisman method, hence, can determine successfully the critical surface tension of Chinese medicine tablet and will become an effective manner to control tablet film coating quality.
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.
文摘Different material properties leads to different metal fracture behaviors. Even if the powder material is composed of plastic metal, the fracture still does not show macroscopic plastic deformation characteristics if the material contains a large number of voids. Eight node isoparametric elastic plastic finite element method was used to simulate the tensile process of sintered powder material. By setting a number of voids in the analyzed metal cuboid, the initial density was taken into consideration. The material properties of the three dimensional solid for the tensile simulation were defined with reference to the known pure iron material parameters. The load displacement curves during elongation were obtained with a universal testing machine, and then the simulated curves were compared with the experimental results. The factors that cause the stress concentration and strength decrease were analyzed according to the simulated equivalent von Mises stress distribution.
文摘Wind stress impacts on ocean relatively high waves can be perfectly illustrated by a recurrent phenomenon in the Sahara desert. Indeed, on this area where the surface wind can blow without encountering major obstacle out of the sand dunes, these main targets are gradually eroded and displaced by the wind on dozens of meters. This experience highlights the action of wind on granular targets (clusters of sand or water slides) and motivates studies similar to ours, where we want to simulate impact of wind stress and breaking on the spatio-temporal evolution of the envelope of ocean relatively high waves: Impact which can inappropriately deflect the waves on ships, oil platforms or coastal infrastructures. Euler and Navier-Stokes equations allow a mathematical formulation of the gravity wave motion (ocean waves are considered in our work as a system of water particles which are held together by low surface tension) and wind acts on targets through friction forces or stress. Michel Talon stationary phase method is used to numerically solve the equations that model the impact of wind on a stationary Gaussian.
文摘The interfacial tension between FeO-CaO-SiO_2-MgO system slag and Cu-Fe-S system matte was determinated by the X-ray radiograph sessile drop method.The effects of FeO/SiO_2 ratio in the slag,contents of CaO,FeO,ZnO and CaF_2 in the slag on interracial tension and the relation of inter facial tension with the grade of matte and temperature have been studied.The floatation coefficient and film coefficient of slag-matte system has been calculated and the mechanism of the transition of iron and oxygen from slag to matte has also been discussed.
