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RSS2016 Vol. 35, No. 10
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2016, 35(10): 1477-1483.
doi: 10.13433/j.cnki.1003-8728.2016.1001
PDF 1010KB
Abstract:
The mechanical properties of atomic force microscope (AFM) between tip-sample systems were investigated. The model of molecular dynamics between tip-sample systems was established and the hybrid potential was used to simulate the interaction force of the tip-sample system and obtain the expression of force-distance curve. Based on the expression, the dynamic equation of the tip-sample system was established and the influence of different sample materials on the dynamical characteristic in AFM-coupled system was studied with the multi-scale method and numerical simulation respectively. The simulation results indicate that it has a great impact on the tip of load for different materials and that the force-distance curve fluctuates greatly and should be treated differently. Besides, various periodic motions occur in the tip-sample system and different sample materials have a high impact on the nonlinear behavior of the AFM-coupled system.
The mechanical properties of atomic force microscope (AFM) between tip-sample systems were investigated. The model of molecular dynamics between tip-sample systems was established and the hybrid potential was used to simulate the interaction force of the tip-sample system and obtain the expression of force-distance curve. Based on the expression, the dynamic equation of the tip-sample system was established and the influence of different sample materials on the dynamical characteristic in AFM-coupled system was studied with the multi-scale method and numerical simulation respectively. The simulation results indicate that it has a great impact on the tip of load for different materials and that the force-distance curve fluctuates greatly and should be treated differently. Besides, various periodic motions occur in the tip-sample system and different sample materials have a high impact on the nonlinear behavior of the AFM-coupled system.
2016, 35(10): 1484-1488.
doi: 10.13433/j.cnki.1003-8728.2016.1002
Abstract:
Tunnel boring machine (TBM) is a kind of the complex engineering machinery in tunnel boring. Cutterhead is a key part of TBM, which holds tens of cutters to bore. The force and torque on cutterhead are easy to generate cracks and reduce its lifetime. TBM lifetime depends on cutterhead lifetime. To investigate cutterhead lifetime, a method to calculate stress with dynamics and finite element method has been proposed. The calculation cutterhead stresses have been compared with that via in-situ experiement, which the error is only of 13%. According to the stress distribution, the dynamic stresses have been divided into eight levels. With the stress-lifetime curve of material, the prediction initiation lifetime of cutterhead is of 84 days. This result could offer anti-fatigue reference for cutterhead design and maintenance period accordance for construction.
Tunnel boring machine (TBM) is a kind of the complex engineering machinery in tunnel boring. Cutterhead is a key part of TBM, which holds tens of cutters to bore. The force and torque on cutterhead are easy to generate cracks and reduce its lifetime. TBM lifetime depends on cutterhead lifetime. To investigate cutterhead lifetime, a method to calculate stress with dynamics and finite element method has been proposed. The calculation cutterhead stresses have been compared with that via in-situ experiement, which the error is only of 13%. According to the stress distribution, the dynamic stresses have been divided into eight levels. With the stress-lifetime curve of material, the prediction initiation lifetime of cutterhead is of 84 days. This result could offer anti-fatigue reference for cutterhead design and maintenance period accordance for construction.
2016, 35(10): 1489-1493.
doi: 10.13433/j.cnki.1003-8728.2016.1003
Abstract:
Due to the structural complexity, finite element modeling of TBM cutterhead will spend a lot of time. The parametric modeling method for finite element analysis of typical TBM cutterhead is established base on the ANSYS Parametric Design Language. And the modal experiment of TBM cutterhead is employed to verify the reliability of the modeling method. The results show that the maximum error between the numerical value and the experimental value of the natural frequencies of cutterhead is only 6.58%. The finite element model of the cutterhead accomplished by our method can well reflect the natural characteristic of physical model and it can be used as the base model of the related simulation. The study results can provide reference for the optimization design of cutterhead and the rapid finite element modeling of complex structure.
Due to the structural complexity, finite element modeling of TBM cutterhead will spend a lot of time. The parametric modeling method for finite element analysis of typical TBM cutterhead is established base on the ANSYS Parametric Design Language. And the modal experiment of TBM cutterhead is employed to verify the reliability of the modeling method. The results show that the maximum error between the numerical value and the experimental value of the natural frequencies of cutterhead is only 6.58%. The finite element model of the cutterhead accomplished by our method can well reflect the natural characteristic of physical model and it can be used as the base model of the related simulation. The study results can provide reference for the optimization design of cutterhead and the rapid finite element modeling of complex structure.
2016, 35(10): 1494-1498.
doi: 10.13433/j.cnki.1003-8728.2016.1004
Abstract:
In this paper, the impact of micro-scale turbulence wind speed on wind power generation is studied. The relationship between some key parameters such as the accumulator effective volume, unit mass storage, state of charge and turbulence parts is analyzed when the mean of the micro-scale turbulence wind speed is the rated wind speed. Based on that, a hydrostatic wind power generation system and its corresponding control method are proposed, which can not only realize the short-term storage energy, but also keep a wind turbine working at the rated power. Finally, for the 10 kw hydrostatic wind power generation system with an accumulator implementing short-term storage energy, the simulation analysis is carried out when the micro-scale turbulence intensity is 12% of the rated wind speed. The simulation results show that the output energy of the hydrostatic wind power generation system with a short-term storage accumulator is 11.3% larger than that of the corresponding system without accumulator.
In this paper, the impact of micro-scale turbulence wind speed on wind power generation is studied. The relationship between some key parameters such as the accumulator effective volume, unit mass storage, state of charge and turbulence parts is analyzed when the mean of the micro-scale turbulence wind speed is the rated wind speed. Based on that, a hydrostatic wind power generation system and its corresponding control method are proposed, which can not only realize the short-term storage energy, but also keep a wind turbine working at the rated power. Finally, for the 10 kw hydrostatic wind power generation system with an accumulator implementing short-term storage energy, the simulation analysis is carried out when the micro-scale turbulence intensity is 12% of the rated wind speed. The simulation results show that the output energy of the hydrostatic wind power generation system with a short-term storage accumulator is 11.3% larger than that of the corresponding system without accumulator.
2016, 35(10): 1499-1504.
doi: 10.13433/j.cnki.1003-8728.2016.1005
Abstract:
Considering the coupled motion and displacement coordination relationship of basic layer, viscoelastic layer and piezoelectric layer, we establish the dynamic equations of plate with smart constrained layer damping based on the Kirchhoff thin plate theory. The elastic structure damping of basic layer was taken into account using proportional damping, and the global dynamic analysis equations of finite element was established based Golla-Hughes-Mctavish (GHM) model to represent the mechanical characterization of viscoelastic materials varying with temperature and frequency. The comparison of theoretical calculation and modal experiments for kinetic parameters was conducted with the examples of clamped-clamped plate with partially treated smart constrained layer damping. The results show that the analysis results considering basic layer damping are closer to the experiment, significantly better than the results without considering basic layer damping. The finite element dynamic model can be obtained accurately by lesser dissipation of degrees of freedom using the method of introducing GHM model in global dynamic equations, and the computation cost can also be reduced.
Considering the coupled motion and displacement coordination relationship of basic layer, viscoelastic layer and piezoelectric layer, we establish the dynamic equations of plate with smart constrained layer damping based on the Kirchhoff thin plate theory. The elastic structure damping of basic layer was taken into account using proportional damping, and the global dynamic analysis equations of finite element was established based Golla-Hughes-Mctavish (GHM) model to represent the mechanical characterization of viscoelastic materials varying with temperature and frequency. The comparison of theoretical calculation and modal experiments for kinetic parameters was conducted with the examples of clamped-clamped plate with partially treated smart constrained layer damping. The results show that the analysis results considering basic layer damping are closer to the experiment, significantly better than the results without considering basic layer damping. The finite element dynamic model can be obtained accurately by lesser dissipation of degrees of freedom using the method of introducing GHM model in global dynamic equations, and the computation cost can also be reduced.
2016, 35(10): 1505-1512.
doi: 10.13433/j.cnki.1003-8728.2016.1006
Abstract:
In order to obtain all structures of eight-bar mechanism, a type synthesis method for eight-bar one degree of freedom (DoF) multiple-joint mechanism is proposed based on the group adjacent matrix. Firstly, according to the number of bars and degree of freedom, we analyze all combination of the Assur groups and construct the diagonal elements of group adjacent matrix. Then, for difference in the numbers and types of multiple-joint, the mechanisms are divided into different types with multiple-joint factor (v) of 1~4, and the Assur groups are connected to former linkages or joints to form the multiple pair linkage or multiple-joint. Meanwhile the other elements of the group adjacent matrix are progressively constructed and the isomorphism is identified in synchronism. Finally, all the groups are connected and all types of eight-bars multiple-joint mechanisms are obtained. The present structural design method generates a total of 681 kinds of structural forms for eight-bar one-DoF multiple-joint.
In order to obtain all structures of eight-bar mechanism, a type synthesis method for eight-bar one degree of freedom (DoF) multiple-joint mechanism is proposed based on the group adjacent matrix. Firstly, according to the number of bars and degree of freedom, we analyze all combination of the Assur groups and construct the diagonal elements of group adjacent matrix. Then, for difference in the numbers and types of multiple-joint, the mechanisms are divided into different types with multiple-joint factor (v) of 1~4, and the Assur groups are connected to former linkages or joints to form the multiple pair linkage or multiple-joint. Meanwhile the other elements of the group adjacent matrix are progressively constructed and the isomorphism is identified in synchronism. Finally, all the groups are connected and all types of eight-bars multiple-joint mechanisms are obtained. The present structural design method generates a total of 681 kinds of structural forms for eight-bar one-DoF multiple-joint.
2016, 35(10): 1513-1519.
doi: 10.13433/j.cnki.1003-8728.2016.1007
Abstract:
An approach was proposed to estimate the servomotor parameter of a 3-DOF motion platform of flight simulator. The motion platform was composed of a moving platform, a static platform, three unconstrained active branch chains and a just constraint driven branch chain. It was proposed that the just constraint driven branch chain was composed of a pneumatic support unit and a mechanism. The moving platform was limited by the mechanism. In order to reduce the active branch driving force, the weight of motion platform and the main load were borne by the pneumatic support unit through the compressed gas. The inverse dynamic model was established by the virtual work principle in the worst case. The estimation and selection of servomotor parameter were studied for the worst case of the motion platform based on the inverse dynamic model. In the example study, the influence of the force which was provided by pneumatic support unit on the peak torque of servomotor was studied. Servomotor parameters were checked by part of the take-off process on the flight from Qingdao to Beijing, and the effectiveness of the method and the rationality of the servomotor were proved.
An approach was proposed to estimate the servomotor parameter of a 3-DOF motion platform of flight simulator. The motion platform was composed of a moving platform, a static platform, three unconstrained active branch chains and a just constraint driven branch chain. It was proposed that the just constraint driven branch chain was composed of a pneumatic support unit and a mechanism. The moving platform was limited by the mechanism. In order to reduce the active branch driving force, the weight of motion platform and the main load were borne by the pneumatic support unit through the compressed gas. The inverse dynamic model was established by the virtual work principle in the worst case. The estimation and selection of servomotor parameter were studied for the worst case of the motion platform based on the inverse dynamic model. In the example study, the influence of the force which was provided by pneumatic support unit on the peak torque of servomotor was studied. Servomotor parameters were checked by part of the take-off process on the flight from Qingdao to Beijing, and the effectiveness of the method and the rationality of the servomotor were proved.
2016, 35(10): 1520-1524.
doi: 10.13433/j.cnki.1003-8728.2016.1008
Abstract:
This paper analyzes the dynamic response of a variable thickness rectangular thin plate on a viscoelastic foundation. The viscoelastic characteristic of the foundation is described with Kelvin-Voigt model with fractional order differential. The governing differential equation of variable thickness rectangular plate on a viscoelastic foundation is established based on the basic hypothesis of elastic plate. The numerical solution of the fractional order differential equation with variable coefficient is obtained with the Galerkin method and the Haar wavelet collocation method. The dynamic response characteristics of the simply supported plate are analyzed, and the central deflection curves of linear model and the parabola model plate under uniform loading are obtained. The influences of length-width ratio and thickness ratio of the rectangular variable thickness plate, and the fractional order, spring coefficient, viscosity coefficient and horizontal shear parameter of the foundation on the dynamic characteristics of the plate are discussed.
This paper analyzes the dynamic response of a variable thickness rectangular thin plate on a viscoelastic foundation. The viscoelastic characteristic of the foundation is described with Kelvin-Voigt model with fractional order differential. The governing differential equation of variable thickness rectangular plate on a viscoelastic foundation is established based on the basic hypothesis of elastic plate. The numerical solution of the fractional order differential equation with variable coefficient is obtained with the Galerkin method and the Haar wavelet collocation method. The dynamic response characteristics of the simply supported plate are analyzed, and the central deflection curves of linear model and the parabola model plate under uniform loading are obtained. The influences of length-width ratio and thickness ratio of the rectangular variable thickness plate, and the fractional order, spring coefficient, viscosity coefficient and horizontal shear parameter of the foundation on the dynamic characteristics of the plate are discussed.
2016, 35(10): 1525-1530.
doi: 10.13433/j.cnki.1003-8728.2016.1009
Abstract:
For metal powder shock compaction, the particles number in the model created are far below the actual number due to the difficulty to simulate the pressing process via finite element software. As a consequent, the deviation of results would be so large that the quality of die and other relevant parameters need to be optimized. In order to complete the optimization, ABAQUS was used to establish a discrete density volleyball accumulation model for aluminum powder according to the SHPB experiment, and the number of particles in the lateral and longitudinal direction of the model was increased regularly to build the relationship between the number of particles in simulation and relative quality of die. The relationship between particle rows of transverse and portrait with the quality of the die were obtained through the simulation results. The relative quality of discrete density volleyball accumulation model is 0.093. The relationship built was applicable for other materials by comparing the experimental results of copper powder with the simulation results.
For metal powder shock compaction, the particles number in the model created are far below the actual number due to the difficulty to simulate the pressing process via finite element software. As a consequent, the deviation of results would be so large that the quality of die and other relevant parameters need to be optimized. In order to complete the optimization, ABAQUS was used to establish a discrete density volleyball accumulation model for aluminum powder according to the SHPB experiment, and the number of particles in the lateral and longitudinal direction of the model was increased regularly to build the relationship between the number of particles in simulation and relative quality of die. The relationship between particle rows of transverse and portrait with the quality of the die were obtained through the simulation results. The relative quality of discrete density volleyball accumulation model is 0.093. The relationship built was applicable for other materials by comparing the experimental results of copper powder with the simulation results.
2016, 35(10): 1531-1537.
doi: 10.13433/j.cnki.1003-8728.2016.1010
Abstract:
Combined with the traditional point contact lubrication problem and fractal contact theory, and introduced the microscopic parameters associated with the surface morphology into the partial elastohydro-dynamic (EHL) lubrication problem, the micro elastohydro-dynamic fractal point contact analysis model is established for the machine joint surfaces on lubrication condition. By non-dimensionalizing these analysis model, the Reynolds equation, film thickness equation and load balance equation are discretized with finite difference method and nine points Simpson method of double integral in the solving domain separately. Then three-dimensional distribution of the oil film pressure and the oil film thickness are calculated using the method of multigrid method and multigrid integration method, respectively. From the calculation results, it can be seen that the oil film shrink phenomenon will appear near the oil film pressure peak when the micro contact surface has certain roughness.
Combined with the traditional point contact lubrication problem and fractal contact theory, and introduced the microscopic parameters associated with the surface morphology into the partial elastohydro-dynamic (EHL) lubrication problem, the micro elastohydro-dynamic fractal point contact analysis model is established for the machine joint surfaces on lubrication condition. By non-dimensionalizing these analysis model, the Reynolds equation, film thickness equation and load balance equation are discretized with finite difference method and nine points Simpson method of double integral in the solving domain separately. Then three-dimensional distribution of the oil film pressure and the oil film thickness are calculated using the method of multigrid method and multigrid integration method, respectively. From the calculation results, it can be seen that the oil film shrink phenomenon will appear near the oil film pressure peak when the micro contact surface has certain roughness.
2016, 35(10): 1538-1543.
doi: 10.13433/j.cnki.1003-8728.2016.1011
Abstract:
To obtain the law of effects of structural parameters of a lathe saddle on its dynamic characteristics, we study the lathe saddle of the high-speed precision CNC ADGM35 and establish its finite element model. Combined with the orthogonal experimental design method, key structural parameters were taken as factors, and the first two-order natural frequency and the mass of saddle as experimental indices, the three-factors and five-level orthogonal experiment is carried out. With the range method and the variance method, the law of effect of the structural parameters on the experimental indices is determined. Finally the response surface model of structure parameters and natural frequency and mass is established. The study can provide reference for the optimal design of lathe saddle structure.
To obtain the law of effects of structural parameters of a lathe saddle on its dynamic characteristics, we study the lathe saddle of the high-speed precision CNC ADGM35 and establish its finite element model. Combined with the orthogonal experimental design method, key structural parameters were taken as factors, and the first two-order natural frequency and the mass of saddle as experimental indices, the three-factors and five-level orthogonal experiment is carried out. With the range method and the variance method, the law of effect of the structural parameters on the experimental indices is determined. Finally the response surface model of structure parameters and natural frequency and mass is established. The study can provide reference for the optimal design of lathe saddle structure.
2016, 35(10): 1544-1549.
doi: 10.13433/j.cnki.1003-8728.2016.1012
Abstract:
A new 3-RPRS parallel mechanism is proposed and its degrees of freedom are calculated. Kinematics based on 3-RPRS parallel mechanism were studied, and the lengths between the three moving platforms were regarded as the restrict conditions to obtain the constrained equations and thus a closed-form solution of the forward position problem of the parallel mechanism was studied. The vertex coordinates on the moving platform are expressed on the fixed coordinate system by coordinate transformation method. Based on the constant length between the three vertexes constraint equations are obtained, and then inverse problem for the mechanism are gotten. A numerical verification was put up to the results of the forward and inverse problems. The forward problem is coincident with the inverse problem. Lastly, application of joint of hopping robot of 3-RPRS parallel mechanism was researched.
A new 3-RPRS parallel mechanism is proposed and its degrees of freedom are calculated. Kinematics based on 3-RPRS parallel mechanism were studied, and the lengths between the three moving platforms were regarded as the restrict conditions to obtain the constrained equations and thus a closed-form solution of the forward position problem of the parallel mechanism was studied. The vertex coordinates on the moving platform are expressed on the fixed coordinate system by coordinate transformation method. Based on the constant length between the three vertexes constraint equations are obtained, and then inverse problem for the mechanism are gotten. A numerical verification was put up to the results of the forward and inverse problems. The forward problem is coincident with the inverse problem. Lastly, application of joint of hopping robot of 3-RPRS parallel mechanism was researched.
2016, 35(10): 1550-1555.
doi: 10.13433/j.cnki.1003-8728.2016.1013
Abstract:
In view of existing overloading error for the industrial robot, especially the industrial robot general problems:the terminal trajectory has low precision; the calculation of real-time monitoring is complex and so on. In this paper, the way of extended Kalman filters combined with registration algorithm is proposed to improve position precision of the robot, the problems such as the low precision of terminal trajectory and the inaccurate analysis of control compensation have been solved. First, the mathematical model of SCARA robot and error analysis evaluation model are established. Based on extended Kalman filters and registration algorithm, the terminal trajectory precision has been improved. As result, through simulation by professional software, analyzing the difference of using algorithm and not using algorithm, the reliability and accuracy of the algorithm is proved.
In view of existing overloading error for the industrial robot, especially the industrial robot general problems:the terminal trajectory has low precision; the calculation of real-time monitoring is complex and so on. In this paper, the way of extended Kalman filters combined with registration algorithm is proposed to improve position precision of the robot, the problems such as the low precision of terminal trajectory and the inaccurate analysis of control compensation have been solved. First, the mathematical model of SCARA robot and error analysis evaluation model are established. Based on extended Kalman filters and registration algorithm, the terminal trajectory precision has been improved. As result, through simulation by professional software, analyzing the difference of using algorithm and not using algorithm, the reliability and accuracy of the algorithm is proved.
2016, 35(10): 1556-1562.
doi: 10.13433/j.cnki.1003-8728.2016.1014
Abstract:
In this paper, an experimental study on the surface radiation noise source identification of the diesel engine was carried out, by the proposed joint information method of near field sound pressure and surface velocity. A single cylinder diesel engine was used in the experiment. Firstly, main radiating components of main radiating surface were identified quickly by near field scan method under engine calibration conditions; the radiation capability of main radiating components was studied based on plate radiation model. Secondly, on the basis of considering influence factor of the sound radiation coefficient, radiation characteristics of structural surface noise for main radiating components were analyzed, compared with the traditional method, identification accuracy was improved; the main noise source from structural noise of main radiating components was further identified with sound insulation. Lastly, recognition results got by the proposed method were verified through noise abatement test. This identification method can provide theoretical guidance for defining goals of the diesel engine noise abatement and low noise structure design.
In this paper, an experimental study on the surface radiation noise source identification of the diesel engine was carried out, by the proposed joint information method of near field sound pressure and surface velocity. A single cylinder diesel engine was used in the experiment. Firstly, main radiating components of main radiating surface were identified quickly by near field scan method under engine calibration conditions; the radiation capability of main radiating components was studied based on plate radiation model. Secondly, on the basis of considering influence factor of the sound radiation coefficient, radiation characteristics of structural surface noise for main radiating components were analyzed, compared with the traditional method, identification accuracy was improved; the main noise source from structural noise of main radiating components was further identified with sound insulation. Lastly, recognition results got by the proposed method were verified through noise abatement test. This identification method can provide theoretical guidance for defining goals of the diesel engine noise abatement and low noise structure design.
2016, 35(10): 1563-1571.
doi: 10.13433/j.cnki.1003-8728.2016.1015
Abstract:
On the basis of deep research on relationship between meshing line and rotor profile, which begins with designing meshing line and then calculates the rotor profiles. After establishing coordinate transformation relations between the male and female rotors, the specific process of reverse design of rotor profile based on the meshing theory is presented. The corresponding rotor profile equations are derived through meshing line consisting of straight line, arc and cubic B-spline curve, respectively. After a meshing line is designed independently according to the research on GHH-type lines, the reverse design method is applied to design a pair of male and female rotor profiles, and the fluid analysis is carried out and compared with GHH-type line. It is found that the performance of these rotor profiles is close to the GHH-type rotor profiles. The experimental results show that the reverse design method can be effectively applied to design the screw rotor profile.
On the basis of deep research on relationship between meshing line and rotor profile, which begins with designing meshing line and then calculates the rotor profiles. After establishing coordinate transformation relations between the male and female rotors, the specific process of reverse design of rotor profile based on the meshing theory is presented. The corresponding rotor profile equations are derived through meshing line consisting of straight line, arc and cubic B-spline curve, respectively. After a meshing line is designed independently according to the research on GHH-type lines, the reverse design method is applied to design a pair of male and female rotor profiles, and the fluid analysis is carried out and compared with GHH-type line. It is found that the performance of these rotor profiles is close to the GHH-type rotor profiles. The experimental results show that the reverse design method can be effectively applied to design the screw rotor profile.
2016, 35(10): 1572-1577.
doi: 10.13433/j.cnki.1003-8728.2016.1016
Abstract:
The MK 7 MOD 3 Arresting Gear has the largest arresting energy among all of the arresting gears of the world; it has operated in the fleet for decades and provides the reliability and safety that is demanded of Aircraft Carrier Operations. The purpose of this paper is to establish detailed numerical dynamic model of the MK 7 MOD 3 Arresting Gear which comprised of hydraulic buffer system, pulley block system and arresting cables. The 3D flexible cable elements are used to build the dynamic model of the arresting cable. The 3D flexible cable elements can describe shape of the bending wave of the arresting cable under serious instantaneous impact. The fluid force of the hydraulic buffer system is described by nonlinear spring-damping element. Except the arresting cable, all of the pulleys and movable parts are modeled by rigid body objects. Validation of the model built in this paper is demonstrated by numerical example. Simulation results show that bending wave shape of the arresting cable can be described precisely. Landing response of the aircraft obtained by using the model presented in this paper matches well with the test data.
The MK 7 MOD 3 Arresting Gear has the largest arresting energy among all of the arresting gears of the world; it has operated in the fleet for decades and provides the reliability and safety that is demanded of Aircraft Carrier Operations. The purpose of this paper is to establish detailed numerical dynamic model of the MK 7 MOD 3 Arresting Gear which comprised of hydraulic buffer system, pulley block system and arresting cables. The 3D flexible cable elements are used to build the dynamic model of the arresting cable. The 3D flexible cable elements can describe shape of the bending wave of the arresting cable under serious instantaneous impact. The fluid force of the hydraulic buffer system is described by nonlinear spring-damping element. Except the arresting cable, all of the pulleys and movable parts are modeled by rigid body objects. Validation of the model built in this paper is demonstrated by numerical example. Simulation results show that bending wave shape of the arresting cable can be described precisely. Landing response of the aircraft obtained by using the model presented in this paper matches well with the test data.
2016, 35(10): 1578-1585.
doi: 10.13433/j.cnki.1003-8728.2016.1017
Abstract:
The deformation mechanisms of double cup extrusion processes with fluttering container were carried out. Deform-3D was employed to simulate the present processes. The influences of the flutter on the mean extrusion load, flow velocity, cup height ratio and stress distribution were analyzed. The simulation results showed that the mean extrusion load under fluttering container decreased and the maximum reduction of load increased with the increasing of fluttering velocity. However, the effect of the fluttering on the load reduction was not significant. The flow velocity of the upper cup wall decreased with the increasing of flutter velocity, that of lower cup wall was opposite in the extrusion process of double cup with fluttering container. On the fluttering velocity below the flow velocity of lower cup wall, the value of cup height ratio was greater than that without fluttering container and increased with the increasing of fluttering velocity. On the fluttering velocity above the flow velocity of the lower cup wall, the direction of the flow velocity of upper cup wall is reversed. Moreover, the less magnitude of cup height ratio was attained and sharply decreased with the increasing of fluttering velocity. The cyclical shift of deformation zone adjacent to container and the almost constant of the maximum stress in the extrusion process with fluttering container were observed.
The deformation mechanisms of double cup extrusion processes with fluttering container were carried out. Deform-3D was employed to simulate the present processes. The influences of the flutter on the mean extrusion load, flow velocity, cup height ratio and stress distribution were analyzed. The simulation results showed that the mean extrusion load under fluttering container decreased and the maximum reduction of load increased with the increasing of fluttering velocity. However, the effect of the fluttering on the load reduction was not significant. The flow velocity of the upper cup wall decreased with the increasing of flutter velocity, that of lower cup wall was opposite in the extrusion process of double cup with fluttering container. On the fluttering velocity below the flow velocity of lower cup wall, the value of cup height ratio was greater than that without fluttering container and increased with the increasing of fluttering velocity. On the fluttering velocity above the flow velocity of the lower cup wall, the direction of the flow velocity of upper cup wall is reversed. Moreover, the less magnitude of cup height ratio was attained and sharply decreased with the increasing of fluttering velocity. The cyclical shift of deformation zone adjacent to container and the almost constant of the maximum stress in the extrusion process with fluttering container were observed.
2016, 35(10): 1586-1592.
doi: 10.13433/j.cnki.1003-8728.2016.1018
Abstract:
The paper analyzed the formation mechanisms of interference on the beating-in and beating-out process of the roller according to the interference of roller and workpiece on the continuous-division cold roll-beating process of an involute spline. The analysis indicates that the interference on the beating-in and beating-out processes respectively appear on the two sides of the keyway contour. The mathematical model for calculating the interference of cold roll-beating is established, and the method for interference characterization with tooth thickness error was put forward. The calculation results indicate that the continuous-division cold roll-beating process of the involute spline has generation characteristics, and the interference mainly concentrates in the bottom part of the involute spline and that the interference is equal on the two sides of keyway contour. The finite element simulation of cold roll-beating process was carried out with DEFORM. The distribution of deformation force was analyzed, the section keyway contour curve was given, and the correctness of analysis and calculation was verified. Further calculation indicates that the interference was proportional to the number of modules of the involute spline and was inversely proportional to the radius of roller gyration and the pressure angle of the involute spline. The quantitative characterization of interference laid the theoretical foundation for angle calculation and roller contour design.
The paper analyzed the formation mechanisms of interference on the beating-in and beating-out process of the roller according to the interference of roller and workpiece on the continuous-division cold roll-beating process of an involute spline. The analysis indicates that the interference on the beating-in and beating-out processes respectively appear on the two sides of the keyway contour. The mathematical model for calculating the interference of cold roll-beating is established, and the method for interference characterization with tooth thickness error was put forward. The calculation results indicate that the continuous-division cold roll-beating process of the involute spline has generation characteristics, and the interference mainly concentrates in the bottom part of the involute spline and that the interference is equal on the two sides of keyway contour. The finite element simulation of cold roll-beating process was carried out with DEFORM. The distribution of deformation force was analyzed, the section keyway contour curve was given, and the correctness of analysis and calculation was verified. Further calculation indicates that the interference was proportional to the number of modules of the involute spline and was inversely proportional to the radius of roller gyration and the pressure angle of the involute spline. The quantitative characterization of interference laid the theoretical foundation for angle calculation and roller contour design.
2016, 35(10): 1593-1596.
doi: 10.13433/j.cnki.1003-8728.2016.1019
Abstract:
An approach based on the minimum amplitude of loaded transmission error, meshing impact force and acceleration of vibration of drive spur gears was proposed to improve meshing performances. The real modified tooth surface was represented by a sum of two vector functions that determine the theoretical tooth surface, and a dynamic model of spur gears was built according to the TCA and LTCA, and the genetic algorithm was used to optimize the parameters of the best deviation surface. The results show that the loaded transmission error is a lin-ear increase in amplitude with the increasing load on theoretical tooth gears; however, its amplitude comes into fluctuations and finally tends to be stable due to increasing contact ratio with increasing load on modified gears; besides, the impact on gear meshing can be avoided with modified gears, which contribute to the reduction of vi-bration greatly.
An approach based on the minimum amplitude of loaded transmission error, meshing impact force and acceleration of vibration of drive spur gears was proposed to improve meshing performances. The real modified tooth surface was represented by a sum of two vector functions that determine the theoretical tooth surface, and a dynamic model of spur gears was built according to the TCA and LTCA, and the genetic algorithm was used to optimize the parameters of the best deviation surface. The results show that the loaded transmission error is a lin-ear increase in amplitude with the increasing load on theoretical tooth gears; however, its amplitude comes into fluctuations and finally tends to be stable due to increasing contact ratio with increasing load on modified gears; besides, the impact on gear meshing can be avoided with modified gears, which contribute to the reduction of vi-bration greatly.
2016, 35(10): 1597-1602.
doi: 10.13433/j.cnki.1003-8728.2016.1020
Abstract:
In order to predict the microstructure change and the micro-hardness change in the cutting process of Inconel 718, the simulation results were compared with the experimental and the best parameters of J-C model for Inconel 718 were found, and then the FEM calibration was furtherly used to calibrate the other physics parameters to make the simulations more perfect. The second-development for Deform-2D was made, the grain refinement was simulated via Zener-Hollomon equation, and the micro-hardness was simulated via Hall-Petch equation. Finally, the microstructure and micro-hardness were simulated in the cutting process of Inconel 718, and the corresponding results can provide reliable judgement for the cutting surface property of Inconel 718.
In order to predict the microstructure change and the micro-hardness change in the cutting process of Inconel 718, the simulation results were compared with the experimental and the best parameters of J-C model for Inconel 718 were found, and then the FEM calibration was furtherly used to calibrate the other physics parameters to make the simulations more perfect. The second-development for Deform-2D was made, the grain refinement was simulated via Zener-Hollomon equation, and the micro-hardness was simulated via Hall-Petch equation. Finally, the microstructure and micro-hardness were simulated in the cutting process of Inconel 718, and the corresponding results can provide reliable judgement for the cutting surface property of Inconel 718.
2016, 35(10): 1603-1608.
doi: 10.13433/j.cnki.1003-8728.2016.1021
Abstract:
In order to solve the response speed and operation efficiency of airborne electro-hydrostatic actuator (EHA) both, a pump and valve coordinated control EHA was designed and simulated with MATLAB/SIMULINK software. Firstly, the EHA composition and structure principle were described by combing typical EHA with direct drive valve, and three mutually backup work patterns were proposed according to the different flight phases. Then, considering the EHA complexity and nonlinearity, we established the pump control and valve control models respectively. Lastly, the EHA controller was designed and the computer simulation was carried out for the performance requirements of a certain type of flight control systems. The experimental results show that the pump and valve coordinated control EHA has higher precision and stability, and the valve control system's dynamic response characteristics is superior to that of pump control system.
In order to solve the response speed and operation efficiency of airborne electro-hydrostatic actuator (EHA) both, a pump and valve coordinated control EHA was designed and simulated with MATLAB/SIMULINK software. Firstly, the EHA composition and structure principle were described by combing typical EHA with direct drive valve, and three mutually backup work patterns were proposed according to the different flight phases. Then, considering the EHA complexity and nonlinearity, we established the pump control and valve control models respectively. Lastly, the EHA controller was designed and the computer simulation was carried out for the performance requirements of a certain type of flight control systems. The experimental results show that the pump and valve coordinated control EHA has higher precision and stability, and the valve control system's dynamic response characteristics is superior to that of pump control system.
2016, 35(10): 1609-1612.
doi: 10.13433/j.cnki.1003-8728.2016.1022
Abstract:
The side-pull tilted single axis tracking PV system has an innovation of the structural design idea, which removes the driving force far away from the rotating axis, introduces the conception of lever principle to reduce the driving force, and reduces the tracking control radius leading to increase the accuracy of tracker, and introduces the geometric principle of "three points determine a plane" to improve the running stability. The new design of double-deck brackets lowered the center of gravity to effectively enhance the instability of the wind disturbances. The power generation of the solar PV system was tested and a comparative test shows the increase of daily power generation of the side-pull tilted single axis tracker is 28.9% to 51%. The results show that the side-pull tilted single axis tracking PV system can gain more electricity steady even in a partly-cloudy weather. The monthly average increase of power generation efficiency is 40.77% than the fixed one, which performs very close even beyond a dual axis tracking system.
The side-pull tilted single axis tracking PV system has an innovation of the structural design idea, which removes the driving force far away from the rotating axis, introduces the conception of lever principle to reduce the driving force, and reduces the tracking control radius leading to increase the accuracy of tracker, and introduces the geometric principle of "three points determine a plane" to improve the running stability. The new design of double-deck brackets lowered the center of gravity to effectively enhance the instability of the wind disturbances. The power generation of the solar PV system was tested and a comparative test shows the increase of daily power generation of the side-pull tilted single axis tracker is 28.9% to 51%. The results show that the side-pull tilted single axis tracking PV system can gain more electricity steady even in a partly-cloudy weather. The monthly average increase of power generation efficiency is 40.77% than the fixed one, which performs very close even beyond a dual axis tracking system.
2016, 35(10): 1613-1617.
doi: 10.13433/j.cnki.1003-8728.2016.1023
Abstract:
In this paper, an average luminous intensity of multiple calibration device for luminosity and light color spatial distribution of Light emitting diode (LED) is studied. In order to improve the gauging accuracy, the precision requirement of the distance and fixed position device in the gauging system is proposed through analyzing the effect of average luminous intensity by the measurement distance and the installation angle deviation of LED in the far/near field. The displacement platform that is able to meet accuracy requirements is used to realize the distance adjustment in far/near field; the profile image of LED is captured with charge-coupled device (CCD), the installation of LED is accurately positioned by using the Hough transform with image centroid method, therefore to improve the gauging accuracy of average luminous intensity for LED and to ensure the gauging system has good reliability.
In this paper, an average luminous intensity of multiple calibration device for luminosity and light color spatial distribution of Light emitting diode (LED) is studied. In order to improve the gauging accuracy, the precision requirement of the distance and fixed position device in the gauging system is proposed through analyzing the effect of average luminous intensity by the measurement distance and the installation angle deviation of LED in the far/near field. The displacement platform that is able to meet accuracy requirements is used to realize the distance adjustment in far/near field; the profile image of LED is captured with charge-coupled device (CCD), the installation of LED is accurately positioned by using the Hough transform with image centroid method, therefore to improve the gauging accuracy of average luminous intensity for LED and to ensure the gauging system has good reliability.
2016, 35(10): 1618-1623.
doi: 10.13433/j.cnki.1003-8728.2016.1024
Abstract:
Contact wire is subjected to fatigue failure under the impact of the pantograph in real operation conditions. It is of great significant to analyze its fatigue reliability. In order to solve the problem of lacking actual data, this article proposes a method of evaluating the contact wire fatigue reliability based on pantograph-catenary dynamic simulation. Weibull distribution is adopted to describe the fatigue life of contact wire. The fatigue reliability expressed by working life and stress cycle is deduced with its S-N curve. The stress cycle of the weakest element is calculated by solving the high-speed pantograph-catenary equation at the basis of modal analysis method. The fatigue reliability curve is drawn by substituting the mean value and amplitude value of each stress cycle obtained by rain flow count method into the reliability model. And the influence of the pre-tension change on the fatigue reliability is studied. And the influence of the pre-tension change on the fatigue reliability is studied. For the numerical example, the fatigue reliability of the contact wire decreases to 0.98 after 9 years. The increase of the pre-tension will result in the loss of reliability.
Contact wire is subjected to fatigue failure under the impact of the pantograph in real operation conditions. It is of great significant to analyze its fatigue reliability. In order to solve the problem of lacking actual data, this article proposes a method of evaluating the contact wire fatigue reliability based on pantograph-catenary dynamic simulation. Weibull distribution is adopted to describe the fatigue life of contact wire. The fatigue reliability expressed by working life and stress cycle is deduced with its S-N curve. The stress cycle of the weakest element is calculated by solving the high-speed pantograph-catenary equation at the basis of modal analysis method. The fatigue reliability curve is drawn by substituting the mean value and amplitude value of each stress cycle obtained by rain flow count method into the reliability model. And the influence of the pre-tension change on the fatigue reliability is studied. And the influence of the pre-tension change on the fatigue reliability is studied. For the numerical example, the fatigue reliability of the contact wire decreases to 0.98 after 9 years. The increase of the pre-tension will result in the loss of reliability.
2016, 35(10): 1624-1628.
doi: 10.13433/j.cnki.1003-8728.2016.1025
Abstract:
Aiming at the complexity characteristics of automobile safety optimization and considering the less deformation of the part of the rear structure, a compensation response surface model was created by generating optimal latin square design through the small sample data spanning the simplified model and high accuracy model. And then, a new RBF(radical basis function)response surface model was established on the basis of new test data which was received through the simplified model and compensation response surface model. The method is applied to vehicle 100% frontal impact multi-objective optimization design for the lightest quality and minimum body B column peak acceleration through selecting 7 parts which influence greater than the others of the front structure. The results show that the method can ensure the model precision, rapid convergence to the optimal solution.
Aiming at the complexity characteristics of automobile safety optimization and considering the less deformation of the part of the rear structure, a compensation response surface model was created by generating optimal latin square design through the small sample data spanning the simplified model and high accuracy model. And then, a new RBF(radical basis function)response surface model was established on the basis of new test data which was received through the simplified model and compensation response surface model. The method is applied to vehicle 100% frontal impact multi-objective optimization design for the lightest quality and minimum body B column peak acceleration through selecting 7 parts which influence greater than the others of the front structure. The results show that the method can ensure the model precision, rapid convergence to the optimal solution.
2016, 35(10): 1629-1635.
doi: 10.13433/j.cnki.1003-8728.2016.1026
Abstract:
For the accurate identification of the physical modes of the aluminum corrugated-section plate with cavities, the hammer excitation method is hired to obtain the frequency response functions of the plate and its modal parameters are identified. In the modal parameter identification, the results obtained by using two methods are compared, and the two methods are, respectively, called the complex mode indicator function and the stabilization diagram. The influence of acoustic modes on the vibration modes is analyzed through the acoustic-vibration test, and the multiple roots are validated by using the modal assurance criterion (MAC). The accuracy of the two methods is validated through comparing the simulation results. The influence of damping materials by means of identification of modal parameters after the multiple roots validated is further analyzed. The obtained conclusions are as follows:as for the plate of aluminum corrugated section, the physical modes can be recognized with the complex mode indicator function with the aid of acoustic-vibration test; using the damping material can improve the modal damping significantly and dramatically reduce modal density at 500 Hz, 1250 Hz and 1600 Hz. This type of damping material is suitable for use of high speed train car roof, roof, side wall and side panels with low vibration and noise, according to the measured frequency spectrum of plate vibration of high-speed trains from the fields.
For the accurate identification of the physical modes of the aluminum corrugated-section plate with cavities, the hammer excitation method is hired to obtain the frequency response functions of the plate and its modal parameters are identified. In the modal parameter identification, the results obtained by using two methods are compared, and the two methods are, respectively, called the complex mode indicator function and the stabilization diagram. The influence of acoustic modes on the vibration modes is analyzed through the acoustic-vibration test, and the multiple roots are validated by using the modal assurance criterion (MAC). The accuracy of the two methods is validated through comparing the simulation results. The influence of damping materials by means of identification of modal parameters after the multiple roots validated is further analyzed. The obtained conclusions are as follows:as for the plate of aluminum corrugated section, the physical modes can be recognized with the complex mode indicator function with the aid of acoustic-vibration test; using the damping material can improve the modal damping significantly and dramatically reduce modal density at 500 Hz, 1250 Hz and 1600 Hz. This type of damping material is suitable for use of high speed train car roof, roof, side wall and side panels with low vibration and noise, according to the measured frequency spectrum of plate vibration of high-speed trains from the fields.
2016, 35(10): 1636-1640.
doi: 10.13433/j.cnki.1003-8728.2016.1027
Abstract:
In order to protect the environment and enhance the car's safety, we take the car roof as the design prototype and design the car roof of aluminum foam sandwich structure, taking into account its lightweight condition. We use the Ansys to do safety analysis of two kinds of the car roof's static performance of falling objects and tipping. The analysis results show that the weight of the car roof of aluminum foam sandwich structure decreases by 32.68% compared with the car roof of prototype structure. In static loading, maximum stress and maximal displacement decreases by 20%. The experiments on falling objects and tipping show that the maximum stress decreases by 5.92% and 27.78% respectively and that the maximal displacement decreases by 35.91% and 20.67% respectively. The car roof of aluminum foam sandwich structure not only realizes the lightweight for energy conservation and emissions reduction but also enhances the car's safety.
In order to protect the environment and enhance the car's safety, we take the car roof as the design prototype and design the car roof of aluminum foam sandwich structure, taking into account its lightweight condition. We use the Ansys to do safety analysis of two kinds of the car roof's static performance of falling objects and tipping. The analysis results show that the weight of the car roof of aluminum foam sandwich structure decreases by 32.68% compared with the car roof of prototype structure. In static loading, maximum stress and maximal displacement decreases by 20%. The experiments on falling objects and tipping show that the maximum stress decreases by 5.92% and 27.78% respectively and that the maximal displacement decreases by 35.91% and 20.67% respectively. The car roof of aluminum foam sandwich structure not only realizes the lightweight for energy conservation and emissions reduction but also enhances the car's safety.
