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RSS2012 Vol. 31, No. 11
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2012, 31(11): 1721-1725.
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Abstract:
Based on comprehensive integration technology,the method for optimal design of V-riblets angle was explored using iSIGHT optimal design platform integrated with fluid dynamics simulation software Fluent.Using Reynolds Averaged N-S formula and RNGk-ε turbulence model,the riblets reduction characteristic was numerically simulated.According to the characteristics of the riblets,computational model,computational grid and boundary conditions were reasonably processed in the numerical simulation.Based on the least resistance,the optimal design model for reblets angle was established,and the reblets angle was optimally designed by adopting the two-stage combining optimal program of overall search based on adaptive simulated annealing algorithm and partial optimal search of sequential quadratic programming.The result shows that V-reblets drag decreases after the optimal design;the relative drag reduction reaches 5.5%;the drag-reducing effect of reblets are greatly improved compared with the initial value,which provides the optimal angle a new method for the optimal design of reblets.
Based on comprehensive integration technology,the method for optimal design of V-riblets angle was explored using iSIGHT optimal design platform integrated with fluid dynamics simulation software Fluent.Using Reynolds Averaged N-S formula and RNGk-ε turbulence model,the riblets reduction characteristic was numerically simulated.According to the characteristics of the riblets,computational model,computational grid and boundary conditions were reasonably processed in the numerical simulation.Based on the least resistance,the optimal design model for reblets angle was established,and the reblets angle was optimally designed by adopting the two-stage combining optimal program of overall search based on adaptive simulated annealing algorithm and partial optimal search of sequential quadratic programming.The result shows that V-reblets drag decreases after the optimal design;the relative drag reduction reaches 5.5%;the drag-reducing effect of reblets are greatly improved compared with the initial value,which provides the optimal angle a new method for the optimal design of reblets.
2012, 31(11): 1726-1730.
Abstract:
According to the physical and mechanical characteristics of rock,combining with the working principle of the conical bit while cutting rock,the mathematical model of single conical bit was built.And it was applied in the whole force analysis of the short helix bit with twelve conical bits and the mathematical model of short helix bit's torque was built.Also the mathematical expression of rotary speed of short helix bit was obtained because the power of the hydraulic piling rig is constant while drilling rock.Grounded on all these above,it can be deducted to a relational expression among drilling speed,cutting thickness and contact strength of rock.In accordance with rock stratum of different contact strength,drilling speed of the machine with different cutting thickness were got by Matlab program,which were compared with those statistics from the practical test under the same condition.From the results,it can be concluded as following: the excessively small cutting thickness will lead to low drilling efficiency because drilling speed isn't maximum,and excessively big cutting thickness will lead to the damage of the machine for the torques can't get over the load(drilling speed is zero).
According to the physical and mechanical characteristics of rock,combining with the working principle of the conical bit while cutting rock,the mathematical model of single conical bit was built.And it was applied in the whole force analysis of the short helix bit with twelve conical bits and the mathematical model of short helix bit's torque was built.Also the mathematical expression of rotary speed of short helix bit was obtained because the power of the hydraulic piling rig is constant while drilling rock.Grounded on all these above,it can be deducted to a relational expression among drilling speed,cutting thickness and contact strength of rock.In accordance with rock stratum of different contact strength,drilling speed of the machine with different cutting thickness were got by Matlab program,which were compared with those statistics from the practical test under the same condition.From the results,it can be concluded as following: the excessively small cutting thickness will lead to low drilling efficiency because drilling speed isn't maximum,and excessively big cutting thickness will lead to the damage of the machine for the torques can't get over the load(drilling speed is zero).
2012, 31(11): 1731-1734.
Abstract:
According to turbines' two typical axial force balance devices,balancing drum and balancing disc,a system model was developed,which contains general mathematic model,basic structure and function parameters characteristic of typical balancing drum and balancing disc.Three parameters of boundary condition coefficient ration,fluid resistance coefficient ration and the sensitivity of flow to pressure changes were defined to extract common laws of these two axial force balance devices.And the model was analyzed by simulation of four typical applications: the effect of boundary conditions of flow 2 on the balance drum's balance force and the flow sensitivity k2,the effect of sealing performance of flow 1 on balance drum's balance force and flow,the relation of boundary conditions coefficient ration with the balance disc's balance force and the flow sensitivity k1,and the effect of sealing performance of flow 4 on balance disc's balance force and flow.
According to turbines' two typical axial force balance devices,balancing drum and balancing disc,a system model was developed,which contains general mathematic model,basic structure and function parameters characteristic of typical balancing drum and balancing disc.Three parameters of boundary condition coefficient ration,fluid resistance coefficient ration and the sensitivity of flow to pressure changes were defined to extract common laws of these two axial force balance devices.And the model was analyzed by simulation of four typical applications: the effect of boundary conditions of flow 2 on the balance drum's balance force and the flow sensitivity k2,the effect of sealing performance of flow 1 on balance drum's balance force and flow,the relation of boundary conditions coefficient ration with the balance disc's balance force and the flow sensitivity k1,and the effect of sealing performance of flow 4 on balance disc's balance force and flow.
2012, 31(11): 1735-1739.
Abstract:
In the process of high-speed milling,cutting force has a very important impact on tool life.This paper focused on modelling the cutting force in high-speed milling.According to oblique cutting model,a cutting force model of flank edge was presented firstly.Differential method was used in this process.The model was approached with calculating instantaneous chip thickness based on real tooth trajectory.Secondly,the cutting force model of chisel edge was adopted with the method of integral.The chisel edge was divided into millions of micro-units along the direction that is normal to cutting edge.We got the cutting force of every unit.Then the model of chisel edge cutting force was gotten by means of integration.Force of the flank edge and the chisel one were combined.In the end,the model was programmed by means of Matlab.The result indicates that the numerical results agree well with the experimental data,the maximum error is 7.14 percent between simulation and the experiment.
In the process of high-speed milling,cutting force has a very important impact on tool life.This paper focused on modelling the cutting force in high-speed milling.According to oblique cutting model,a cutting force model of flank edge was presented firstly.Differential method was used in this process.The model was approached with calculating instantaneous chip thickness based on real tooth trajectory.Secondly,the cutting force model of chisel edge was adopted with the method of integral.The chisel edge was divided into millions of micro-units along the direction that is normal to cutting edge.We got the cutting force of every unit.Then the model of chisel edge cutting force was gotten by means of integration.Force of the flank edge and the chisel one were combined.In the end,the model was programmed by means of Matlab.The result indicates that the numerical results agree well with the experimental data,the maximum error is 7.14 percent between simulation and the experiment.
2012, 31(11): 1740-1743.
Abstract:
Through the analysis of rotor dynamics model,the mathematical formula of influence coefficient matrix was discussed,and the theory that condition number of influence coefficient matrix can measure the accuracy of dynamic balancing was proved.The finite element model of dynamic balance of rotor-bearing system was established by using ANSYS,on which full vector dynamic balancing method and traditional influence coefficient method based on the signal of single-channel were used for rotor dynamic balance.The result shows that the condition number of full vector dynamic balancing method is less than that of traditional influence coefficient method,which proves that full vector dynamic balance method has higher accuracy.The result is also validated by imbalance experimental measurements of double disc on BENTLY rotor experimental table.
Through the analysis of rotor dynamics model,the mathematical formula of influence coefficient matrix was discussed,and the theory that condition number of influence coefficient matrix can measure the accuracy of dynamic balancing was proved.The finite element model of dynamic balance of rotor-bearing system was established by using ANSYS,on which full vector dynamic balancing method and traditional influence coefficient method based on the signal of single-channel were used for rotor dynamic balance.The result shows that the condition number of full vector dynamic balancing method is less than that of traditional influence coefficient method,which proves that full vector dynamic balance method has higher accuracy.The result is also validated by imbalance experimental measurements of double disc on BENTLY rotor experimental table.
2012, 31(11): 1744-1747.
Abstract:
To analyze the radial equivalent stiffness of the elastic-ring flexible support,the Ansys APDL language was used to establish the FEM model,which considers the nonlinear contact between the ring and the supports.The effect of variation of the ring's structural parameters,including the number of the segments,the circumference width of the boss,and the effective thickness of the ring,on the radial equivalent stiffness of the ring was analyzed by using FEM method and its variety laws were obtained.By taking into account the machining,assembly and stability requirement,the optimization analysis was carried out and four referenced structural schemes were provided.
To analyze the radial equivalent stiffness of the elastic-ring flexible support,the Ansys APDL language was used to establish the FEM model,which considers the nonlinear contact between the ring and the supports.The effect of variation of the ring's structural parameters,including the number of the segments,the circumference width of the boss,and the effective thickness of the ring,on the radial equivalent stiffness of the ring was analyzed by using FEM method and its variety laws were obtained.By taking into account the machining,assembly and stability requirement,the optimization analysis was carried out and four referenced structural schemes were provided.
2012, 31(11): 1748-1753.
Abstract:
A three-DOF cable-driven extravehicular planar transport robot with four cables was designed and manufactured.The kinematic models of the robot were established and then solved by Matlab.The trajectory was planned and the changes of the length of the four cables were simulated along the trajectory based the models.Furthermore,the workspace of the robot was analyzed based on the method of orthogonal complement,which can avoid the solving problems brought by the arbitrariness of the vector z.And the kinematic models and the continuous and controllable movement have been verified by an experiment platform.Research shows that the changes of the length of cables are continuous when the robot moves along the planned trajectory,which ensures the smooth and continuous movement of the robot during the whole operation,and the accuracy of positioning and the workspace of the cable-driven robot can also satisfy the task requirements.
A three-DOF cable-driven extravehicular planar transport robot with four cables was designed and manufactured.The kinematic models of the robot were established and then solved by Matlab.The trajectory was planned and the changes of the length of the four cables were simulated along the trajectory based the models.Furthermore,the workspace of the robot was analyzed based on the method of orthogonal complement,which can avoid the solving problems brought by the arbitrariness of the vector z.And the kinematic models and the continuous and controllable movement have been verified by an experiment platform.Research shows that the changes of the length of cables are continuous when the robot moves along the planned trajectory,which ensures the smooth and continuous movement of the robot during the whole operation,and the accuracy of positioning and the workspace of the cable-driven robot can also satisfy the task requirements.
2012, 31(11): 1754-1759.
Abstract:
The function of the transport mechanism is to transfer the lunar rover to the lunar surface safely and to give the initial condition for the independent detection of the lunar rover.The success of a lunar exploration program will be determined by the transport mechanism.This paper reviewed the features and application conditions of the successfully used foreign transport mechanisms and summarized technical characteristics of the principle schemes of the national transport mechanisms.Based on this work,we proposed the principle scheme of the transport mechanism with swing-arm type by combining with the lunar exploration mission objective and the structural characteristics and technical requirements of the lunar lander and the lunar rover in our country.In addition,we analyzed the reliability of the structural and did the corresponding experiments.It is found that the transfer process of the proposed transfer structural system is completely controllable with good predictability,simple structure and high reliability.
The function of the transport mechanism is to transfer the lunar rover to the lunar surface safely and to give the initial condition for the independent detection of the lunar rover.The success of a lunar exploration program will be determined by the transport mechanism.This paper reviewed the features and application conditions of the successfully used foreign transport mechanisms and summarized technical characteristics of the principle schemes of the national transport mechanisms.Based on this work,we proposed the principle scheme of the transport mechanism with swing-arm type by combining with the lunar exploration mission objective and the structural characteristics and technical requirements of the lunar lander and the lunar rover in our country.In addition,we analyzed the reliability of the structural and did the corresponding experiments.It is found that the transfer process of the proposed transfer structural system is completely controllable with good predictability,simple structure and high reliability.
2012, 31(11): 1760-1766.
Abstract:
The excitation induced by the interactions of wheels and subway tracks was discussed.Also,its models and applied methods were depicted.After the introducing of the principle of isolation for floating slab track(FST) and displaying of the structures of FST supported with elastomer and spring,the models of FST,including lumped parameter model,continuous model and discrete model,were demonstrated.Then the dynamic performance,modal analysis and effectiveness of isolation for FST were showed.In order to solve the main isolation problems of FST,the parameter optimization for stiffness and damping constant as well as the semi-active vibration isolation technology or active vibration isolation technology were considered to be the development trend.
The excitation induced by the interactions of wheels and subway tracks was discussed.Also,its models and applied methods were depicted.After the introducing of the principle of isolation for floating slab track(FST) and displaying of the structures of FST supported with elastomer and spring,the models of FST,including lumped parameter model,continuous model and discrete model,were demonstrated.Then the dynamic performance,modal analysis and effectiveness of isolation for FST were showed.In order to solve the main isolation problems of FST,the parameter optimization for stiffness and damping constant as well as the semi-active vibration isolation technology or active vibration isolation technology were considered to be the development trend.
2012, 31(11): 1767-1771.
Abstract:
Optimization of temperature measuring points for machine tool is one of the difficulties of thermal error compensation.Fuzzy group combined with partial correlation analysis was adopted to optimize the temperature measuring points.Temperature measuring points were classified by fuzzy group analysis and F-statistics firstly.Then according to the partial correlation coefficient between thermal error and the temperature measuring points,the key temperature variables are determined.Lastly,by using these key temperature variables,linear regression model of thermal error was established to test prediction accuracy.This method was tested in precision horizontal machining center MCH63.The result shows as following,this method reduces the number of temperature measuring points efficiently;thermal error reduces from about 45 μm to 7 μm.Threshold which is optimized by F-statistics,can quickly and exactly determine the grouping result of the temperature variables.
Optimization of temperature measuring points for machine tool is one of the difficulties of thermal error compensation.Fuzzy group combined with partial correlation analysis was adopted to optimize the temperature measuring points.Temperature measuring points were classified by fuzzy group analysis and F-statistics firstly.Then according to the partial correlation coefficient between thermal error and the temperature measuring points,the key temperature variables are determined.Lastly,by using these key temperature variables,linear regression model of thermal error was established to test prediction accuracy.This method was tested in precision horizontal machining center MCH63.The result shows as following,this method reduces the number of temperature measuring points efficiently;thermal error reduces from about 45 μm to 7 μm.Threshold which is optimized by F-statistics,can quickly and exactly determine the grouping result of the temperature variables.
2012, 31(11): 1772-1775.
Abstract:
Finrstly,integrom,chassis of rhombus concept off-road vehicle was studied at home and abroad.Then the article introduced structural theory of the integrally chassis of rhombus concept off-road vehicle.On this base,the articulated chassis of rhombus concept off-road vehicle was designed to make up for the passing capability of the integrally chassis.The dynamic model of the articulated chassis was built by the software ADAMS and the dynamic simulation was carried out which provides the maximum values of crossing-obstacle and climbing-slope.The simulation results on the pavement adaptability are in good agreement with the test data of the physical prototype test.And the validated dynamical model is available for further analysis and optimization of this kind chassis.
Finrstly,integrom,chassis of rhombus concept off-road vehicle was studied at home and abroad.Then the article introduced structural theory of the integrally chassis of rhombus concept off-road vehicle.On this base,the articulated chassis of rhombus concept off-road vehicle was designed to make up for the passing capability of the integrally chassis.The dynamic model of the articulated chassis was built by the software ADAMS and the dynamic simulation was carried out which provides the maximum values of crossing-obstacle and climbing-slope.The simulation results on the pavement adaptability are in good agreement with the test data of the physical prototype test.And the validated dynamical model is available for further analysis and optimization of this kind chassis.
2012, 31(11): 1776-1780.
Abstract:
300MN forging hydraulic press is the essential equipment of the national defense and the basic construction of our country.The cylinder is an important part of the hydraulic press,the reliability of the hydraulic cylinder affects directly to the production efficiency of the hydraulic presses.This paper selected the material young's modulus,ultimate strength,pressure load inside of the hydraulic cylinder as design variables.Firstly,sampling points were obtained by using latin hypercube experimental design method,and then approximate equation of the model was built by using response surface approximately method.Finally,hydraulic cylinder's reliability index was obtained by using non-probabilistic convex model.As the model's reliability index is 2.054 7,so it proves that the hydraulic cylinder is reliable.
300MN forging hydraulic press is the essential equipment of the national defense and the basic construction of our country.The cylinder is an important part of the hydraulic press,the reliability of the hydraulic cylinder affects directly to the production efficiency of the hydraulic presses.This paper selected the material young's modulus,ultimate strength,pressure load inside of the hydraulic cylinder as design variables.Firstly,sampling points were obtained by using latin hypercube experimental design method,and then approximate equation of the model was built by using response surface approximately method.Finally,hydraulic cylinder's reliability index was obtained by using non-probabilistic convex model.As the model's reliability index is 2.054 7,so it proves that the hydraulic cylinder is reliable.
2012, 31(11): 1781-1785.
Abstract:
The generating of face gear with arcuate tooth was studied in this paper.The value of inner radius and outer radius of face gear,and its manufacture on NC machine were investigated.Tooth surface equation was derived based on the concept of imaginary gear.According to the conditions of undercutting in the dedendum area of inner radius and the pointing of the tooth in the addendum area in outer radius,tooth width limiting value was determined.The machining principle in the general multi-axle numerical control machine tool was created by using coordinate transformation.Then the polynomial expression of motion axes was obtained.An example was employed to analyze the tooth width with different design parameters such as the number of imaginary tooth,cutter head radius,initial tilted angle,etc.Tooth surface model was established,and the result proves the manufacture is feasible.
The generating of face gear with arcuate tooth was studied in this paper.The value of inner radius and outer radius of face gear,and its manufacture on NC machine were investigated.Tooth surface equation was derived based on the concept of imaginary gear.According to the conditions of undercutting in the dedendum area of inner radius and the pointing of the tooth in the addendum area in outer radius,tooth width limiting value was determined.The machining principle in the general multi-axle numerical control machine tool was created by using coordinate transformation.Then the polynomial expression of motion axes was obtained.An example was employed to analyze the tooth width with different design parameters such as the number of imaginary tooth,cutter head radius,initial tilted angle,etc.Tooth surface model was established,and the result proves the manufacture is feasible.
2012, 31(11): 1786-1789.
Abstract:
For fabricating sub-wavelength structure by nanoimprint lithography,the templates for ultraviolet(UV) nanoimprint lithography were prepared by the lithography and the reactive ion etching(RIE) technology on quartz substrates and the influence of the process parameters on photoresist and etching rate was investigated.The surface micrograph of the etched patterns was observed by laser scanning confocal microscope(LSCM) and atomic force microscope(AFM).It is shown that the UV nanoimprint lithography templates fabricated in this work at the optimum process parameter are highly uniform and symmetrical.The UV transmittance properties of the templates were measured by a scanning spectrophotometer.The results demonstrate that the UV transmittance of the etched template is still over 90% at the wavelength of 365 nm.
For fabricating sub-wavelength structure by nanoimprint lithography,the templates for ultraviolet(UV) nanoimprint lithography were prepared by the lithography and the reactive ion etching(RIE) technology on quartz substrates and the influence of the process parameters on photoresist and etching rate was investigated.The surface micrograph of the etched patterns was observed by laser scanning confocal microscope(LSCM) and atomic force microscope(AFM).It is shown that the UV nanoimprint lithography templates fabricated in this work at the optimum process parameter are highly uniform and symmetrical.The UV transmittance properties of the templates were measured by a scanning spectrophotometer.The results demonstrate that the UV transmittance of the etched template is still over 90% at the wavelength of 365 nm.
2012, 31(11): 1790-1795.
Abstract:
In order to stabilize the vehicle in limited driving conditions,a fuzzy direct yaw moment controller was designed to calculate the proper brake force applied to the relevant wheel.The vehicle stability control system is based on following control method.The side slip angle and yaw rate which indicate the vehicle's stability and handling performance were chosen as the control variables.The response of the vehicle model was selected as the reference value.In order to evaluate the performance of the controller,simulations of lane change and J-turn maneuver were carried out.The results show that the stability and handling performance of the vehicle are improved.
In order to stabilize the vehicle in limited driving conditions,a fuzzy direct yaw moment controller was designed to calculate the proper brake force applied to the relevant wheel.The vehicle stability control system is based on following control method.The side slip angle and yaw rate which indicate the vehicle's stability and handling performance were chosen as the control variables.The response of the vehicle model was selected as the reference value.In order to evaluate the performance of the controller,simulations of lane change and J-turn maneuver were carried out.The results show that the stability and handling performance of the vehicle are improved.
2012, 31(11): 1796-1800.
Abstract:
As the main device for connecting smelting furnace and conticaster,ladle plays an important role in continuous casting.The insulation properties of ladle have significant influence on the temperature lowering of liquid steel,the quality improvement of slab,the heat reduction of the package wall,the prolongation of the service life of ladle lining and the reduction of production costs.Insulation properties of the existing ladle were analyzed.The paper presents a new-type ladle lining.A three-dimensional finite element model of ladle based on heat transfer theory and finite element technique was built to carry out the simulation analysis of the new-type ladle and the traditional ladle.The heating time of the new-type ladle is shorter under the same condition,which saves time and energy.The insulation properties of the new-type ladle were testified from two aspects: the temperature of the ladle shell and the temperature drop speed of molten steel.When the average characteristic temperature of the ladle shell is reduced by 45 ℃ or so,the temperature drop speed of molten steel in the ladle will be reduced by 0.27 ℃/min.
As the main device for connecting smelting furnace and conticaster,ladle plays an important role in continuous casting.The insulation properties of ladle have significant influence on the temperature lowering of liquid steel,the quality improvement of slab,the heat reduction of the package wall,the prolongation of the service life of ladle lining and the reduction of production costs.Insulation properties of the existing ladle were analyzed.The paper presents a new-type ladle lining.A three-dimensional finite element model of ladle based on heat transfer theory and finite element technique was built to carry out the simulation analysis of the new-type ladle and the traditional ladle.The heating time of the new-type ladle is shorter under the same condition,which saves time and energy.The insulation properties of the new-type ladle were testified from two aspects: the temperature of the ladle shell and the temperature drop speed of molten steel.When the average characteristic temperature of the ladle shell is reduced by 45 ℃ or so,the temperature drop speed of molten steel in the ladle will be reduced by 0.27 ℃/min.
2012, 31(11): 1801-1805.
Abstract:
Features of planetary transmission system can significantly affect efficiency and reliability of wind turbin.Transmission system structure of 1.5MW wind turbin was analysed and the mathematical model of multi-objective optimization for planetary transmission system of wind turbin was established.It took the minimal volume and the maximal contact ratio as object functions,and fully considered such constraint condition as geometric parameter constraint,performance constraint and reliability strength constraint.Optimization model was given fuzzy treatment to let optimization be more close to actual engineering application.Solution to model of multi-objective fuzzy optimization by genetic algorithms avoids local optimization and gets global optimum result.The method has been applied and the result indicates that volume,stability and bearing capacity of the system are observably improved and reliability is ensured.
Features of planetary transmission system can significantly affect efficiency and reliability of wind turbin.Transmission system structure of 1.5MW wind turbin was analysed and the mathematical model of multi-objective optimization for planetary transmission system of wind turbin was established.It took the minimal volume and the maximal contact ratio as object functions,and fully considered such constraint condition as geometric parameter constraint,performance constraint and reliability strength constraint.Optimization model was given fuzzy treatment to let optimization be more close to actual engineering application.Solution to model of multi-objective fuzzy optimization by genetic algorithms avoids local optimization and gets global optimum result.The method has been applied and the result indicates that volume,stability and bearing capacity of the system are observably improved and reliability is ensured.
2012, 31(11): 1806-1811.
Abstract:
Based on thorough investigation for an engine assembly workshop,Kanban production system was imported and carried out.Some problems caused by implementing traditional push system,such as low production efficiency and equipment utilization rate and long average waiting time of order were solved by simulation and optimization.By comparing various performance indicators Kanban production system implemented before and after,it draws some conclusions that average order delay time is greatly reduced;the equipment utility rate of workshop is increased and comprehensive production benefit of workshop is improved obviously.Meantime,using parameter optimization,it studied further that the different values of safety factor and variation coefficient influence on performance indicators,such as throughput,work-in-process,average waiting time of order and operation rate etc.,of Kanban production system,which will provide a reference for parameter selection of implementation scheme.
Based on thorough investigation for an engine assembly workshop,Kanban production system was imported and carried out.Some problems caused by implementing traditional push system,such as low production efficiency and equipment utilization rate and long average waiting time of order were solved by simulation and optimization.By comparing various performance indicators Kanban production system implemented before and after,it draws some conclusions that average order delay time is greatly reduced;the equipment utility rate of workshop is increased and comprehensive production benefit of workshop is improved obviously.Meantime,using parameter optimization,it studied further that the different values of safety factor and variation coefficient influence on performance indicators,such as throughput,work-in-process,average waiting time of order and operation rate etc.,of Kanban production system,which will provide a reference for parameter selection of implementation scheme.
2012, 31(11): 1812-1815.
Abstract:
Blowout preventer valve in practical work suffers the random shocks of high-pressure liquid in the oil wellhead,and often fails to work due to fatigue failure.This work focused on a large-scale single ram blowout preventer valve,acquired and recorded the working pressure and impact frequency of the valve.The fatigue crack growth process was recorded and observed.The fatigue mechanism of the valve body was discussed.Considering that the work load of the valve body is random,the stochastic finite element method was introduced in the fatigue life analysis of the valve body.The calculation method for the valve body life under random load was proposed.The overall life evaluation and distribution of fatigue life of various parts of valve body are realized.
Blowout preventer valve in practical work suffers the random shocks of high-pressure liquid in the oil wellhead,and often fails to work due to fatigue failure.This work focused on a large-scale single ram blowout preventer valve,acquired and recorded the working pressure and impact frequency of the valve.The fatigue crack growth process was recorded and observed.The fatigue mechanism of the valve body was discussed.Considering that the work load of the valve body is random,the stochastic finite element method was introduced in the fatigue life analysis of the valve body.The calculation method for the valve body life under random load was proposed.The overall life evaluation and distribution of fatigue life of various parts of valve body are realized.
2012, 31(11): 1816-1819.
Abstract:
Bill of material(BOM) is critical for manufacturing enterprises.Though it can supply material requirement planning with fundamental data.Traditional BOM can not describe uncertain time information due to its simplicity.This weakness confines BOM from a wide range of application.A new BOM model which is based on weighted digraph was presented in this paper.The model carried fuzzy time data as well as basic information.In the meanwhile,a time constraint model of material requirement planning was proposed on the base of time distance graph.To transform BOM model into time constraint model of material requirement planning,mapping rules were set.A case study was used to verify the feasibility of the proposed methodology.
Bill of material(BOM) is critical for manufacturing enterprises.Though it can supply material requirement planning with fundamental data.Traditional BOM can not describe uncertain time information due to its simplicity.This weakness confines BOM from a wide range of application.A new BOM model which is based on weighted digraph was presented in this paper.The model carried fuzzy time data as well as basic information.In the meanwhile,a time constraint model of material requirement planning was proposed on the base of time distance graph.To transform BOM model into time constraint model of material requirement planning,mapping rules were set.A case study was used to verify the feasibility of the proposed methodology.
2012, 31(11): 1820-1823,1830.
Abstract:
Because of influences of external environment,design manufacture and other factors,every component's transmission size of spacecraft cargo door locking mechanism should produce deformation and error.It should change motion law of locking mechanism and lead to failure.The kinematic accuracy model of cargo door locking mechanism was built based on every component's size error.Every component's size and error of input angle on error influences of mechanism output position were studied in actual working status.And the kinematic accuracy of cargo door locking mechanism was given.The results show that the size error of locking mechanism's bar 1 and bar 3 for latch hook's ideal working position has most influence on its working range.So their errors should be controlled at machining.
Because of influences of external environment,design manufacture and other factors,every component's transmission size of spacecraft cargo door locking mechanism should produce deformation and error.It should change motion law of locking mechanism and lead to failure.The kinematic accuracy model of cargo door locking mechanism was built based on every component's size error.Every component's size and error of input angle on error influences of mechanism output position were studied in actual working status.And the kinematic accuracy of cargo door locking mechanism was given.The results show that the size error of locking mechanism's bar 1 and bar 3 for latch hook's ideal working position has most influence on its working range.So their errors should be controlled at machining.
2012, 31(11): 1824-1830.
Abstract:
Wind turbine Hub is an important stress bearing and load transmission components,whose strength seriously affected the life of wind turbine.A load applying manner was provided for the strength analysis of Direct-drive Wind Turbine Hub in this paper,which can simulate the real stress of wind turbine hub effectively.Then the ultimate strength analysis of large Direct-drive Wind Turbine Hub was performed by using finite element analysis software MSC.Marc and the fatigue analysis was calculated by applying modified rain-flow Counting Method and Palmgren-Miner Linear Cumulative Damage Law,both of which were carried out according to the German Lloyd(GL) wind turbine certification standards.The results suggest that the strength of hub can meet the life requirements of 20 years,and the present study explored a new analysis method of key components of direct-drive wind turbine,which provides some basic ideas for the structure design of hub.
Wind turbine Hub is an important stress bearing and load transmission components,whose strength seriously affected the life of wind turbine.A load applying manner was provided for the strength analysis of Direct-drive Wind Turbine Hub in this paper,which can simulate the real stress of wind turbine hub effectively.Then the ultimate strength analysis of large Direct-drive Wind Turbine Hub was performed by using finite element analysis software MSC.Marc and the fatigue analysis was calculated by applying modified rain-flow Counting Method and Palmgren-Miner Linear Cumulative Damage Law,both of which were carried out according to the German Lloyd(GL) wind turbine certification standards.The results suggest that the strength of hub can meet the life requirements of 20 years,and the present study explored a new analysis method of key components of direct-drive wind turbine,which provides some basic ideas for the structure design of hub.
2012, 31(11): 1831-1834,1840.
Abstract:
To solve the problem of space limit when orifice-type restrictor and capillary restrictor are applied to hybrid bearings,this paper proposed a kind of non-typical long orifice-type restrictor to satisfy the space of turbine,the size of which is between other two kinds of typical restrictors,and the experimental model was established for this structure.Through analyzing the two types of restrictor structures and flow rate mode,this paper proposed a long small orifice-type restrictor similar to a typical orifice-type restrictor;and a feasible experimental modeling method was proposed,which took use of orifice plate but not the whole bearing.The flow rate of water film restrictor was measured under the aspect ratio of 4~10 and the pressure difference of 1.5 MPa~5.5 MPa,and the experimental model of long orifice-type restrictor was achieved.The result shows that the restrictor of non-typical structures should be modeled by experiment,and the flow discipline of non-typical restrictor given by this paper is familiar with typical orifice-type restrictor,of which the throttling model is almost a turbulence model.
To solve the problem of space limit when orifice-type restrictor and capillary restrictor are applied to hybrid bearings,this paper proposed a kind of non-typical long orifice-type restrictor to satisfy the space of turbine,the size of which is between other two kinds of typical restrictors,and the experimental model was established for this structure.Through analyzing the two types of restrictor structures and flow rate mode,this paper proposed a long small orifice-type restrictor similar to a typical orifice-type restrictor;and a feasible experimental modeling method was proposed,which took use of orifice plate but not the whole bearing.The flow rate of water film restrictor was measured under the aspect ratio of 4~10 and the pressure difference of 1.5 MPa~5.5 MPa,and the experimental model of long orifice-type restrictor was achieved.The result shows that the restrictor of non-typical structures should be modeled by experiment,and the flow discipline of non-typical restrictor given by this paper is familiar with typical orifice-type restrictor,of which the throttling model is almost a turbulence model.
2012, 31(11): 1835-1840.
Abstract:
According to domestic vehicle high-speed safety requirements,this paper proposed to use optimal control method to study vehicle inverse dynamics in high-speed emergency avoidance and repeatedly avoidance condition.The steering angle input of 3-DOF vehicle mode is the control variable;accurately tracking the expected path is the control object;the optimal control problem can be converted into a nonlinear programming problem while using the state variables conversion,which was solved by the sequential quadratic programming(SQP) algorithm.The results show that vehicle can well track the expected path in high speed,and provide high-speed vehicle handling dynamics optimization design the certain reference and theoretical basis through comparing maneuverability of different vehicles tracking the same path in high speed.
According to domestic vehicle high-speed safety requirements,this paper proposed to use optimal control method to study vehicle inverse dynamics in high-speed emergency avoidance and repeatedly avoidance condition.The steering angle input of 3-DOF vehicle mode is the control variable;accurately tracking the expected path is the control object;the optimal control problem can be converted into a nonlinear programming problem while using the state variables conversion,which was solved by the sequential quadratic programming(SQP) algorithm.The results show that vehicle can well track the expected path in high speed,and provide high-speed vehicle handling dynamics optimization design the certain reference and theoretical basis through comparing maneuverability of different vehicles tracking the same path in high speed.
2012, 31(11): 1841-1844,1850.
Abstract:
S-type tube valve is one of the key components widely used in concrete machinery.Its property can directly affect the performance of this kind of machines such as spraying concrete machine.By using the theory of dimensional analysis,its mathematical simulation model which is suitable for computational fluid dynamics software Fluent was made in order to reduce flow resistance through it in concrete spraying machines and to prevent clogging.The optimum proportion of each level length of it was obtained by numerical simulation under given conditions.The optimal parabola equations of it were also built in this paper.
S-type tube valve is one of the key components widely used in concrete machinery.Its property can directly affect the performance of this kind of machines such as spraying concrete machine.By using the theory of dimensional analysis,its mathematical simulation model which is suitable for computational fluid dynamics software Fluent was made in order to reduce flow resistance through it in concrete spraying machines and to prevent clogging.The optimum proportion of each level length of it was obtained by numerical simulation under given conditions.The optimal parabola equations of it were also built in this paper.
2012, 31(11): 1845-1850.
Abstract:
To control the response of engineering structures working in severe vibrating environment,it is necessary to predict and analyze the dynamic characteristics of structures accurately and design the structures dynamically.In the environment vibration experiment,the dynamic boundary condition of the actual structure should be reflected or simulated by the test clamp,which is a design problem of structural dynamic boundary.For these situations,a new method based on topology optimization satisfying natural frequency and mode requirements was investigated.Genetic algorithm was used for topology optimization of boundary plate for a wing frame model as prototype structure.The results show that it is feasible to simulate structural dynamics boundary by topology optimization method.
To control the response of engineering structures working in severe vibrating environment,it is necessary to predict and analyze the dynamic characteristics of structures accurately and design the structures dynamically.In the environment vibration experiment,the dynamic boundary condition of the actual structure should be reflected or simulated by the test clamp,which is a design problem of structural dynamic boundary.For these situations,a new method based on topology optimization satisfying natural frequency and mode requirements was investigated.Genetic algorithm was used for topology optimization of boundary plate for a wing frame model as prototype structure.The results show that it is feasible to simulate structural dynamics boundary by topology optimization method.
2012, 31(11): 1851-1854,1859.
Abstract:
In order to design a servo pressure hydraulic system,its transfer function was derived and the hydraulic components were selected.We analyzed the stability of the transfer function of its control system and designed its PID(Proportional Integral Differential) controller.In order to compare with the traditional PID control method,we designed the immune-particle swarm optimization control algorithm suitable for the servo pressure hydraulic system and applied the control algorithm to the PID control.We also gave the block diagram of the control system.With the crossover operator and the mutation operator of the immune-particle swarm optimization control algorithm,we optimized the new parameters of the control system and used the new optimization results to simulate its optimization.The simulation results show that the transition time for the servo pressure hydraulic system obtained from the immune-particle swarm optimization control algorithm is shorter than the traditional PID control algorithm.
In order to design a servo pressure hydraulic system,its transfer function was derived and the hydraulic components were selected.We analyzed the stability of the transfer function of its control system and designed its PID(Proportional Integral Differential) controller.In order to compare with the traditional PID control method,we designed the immune-particle swarm optimization control algorithm suitable for the servo pressure hydraulic system and applied the control algorithm to the PID control.We also gave the block diagram of the control system.With the crossover operator and the mutation operator of the immune-particle swarm optimization control algorithm,we optimized the new parameters of the control system and used the new optimization results to simulate its optimization.The simulation results show that the transition time for the servo pressure hydraulic system obtained from the immune-particle swarm optimization control algorithm is shorter than the traditional PID control algorithm.
2012, 31(11): 1855-1859.
Abstract:
Based on the property of the integral invariant irrelevant to the meshes' topology and the inner relationship between the volume integral invariant and the mean-curvature,a method was proposed to extract the feature points from scattered point sets based on the mean-curvature and the volume integral invariant.The algorithm in the present method used the global 4D Shepard surface to estimate the curvature of each point in the point cloud and it was only related to the numbers and the operations of the points cloud.Then the volume integral invariant was calculated by the given formula,and the feature points were extracted through the K-Means clustering algorithm.The experiments show that this algorithm has higher computing efficiency,and can express the boundary feature of the clouds more precisely.
Based on the property of the integral invariant irrelevant to the meshes' topology and the inner relationship between the volume integral invariant and the mean-curvature,a method was proposed to extract the feature points from scattered point sets based on the mean-curvature and the volume integral invariant.The algorithm in the present method used the global 4D Shepard surface to estimate the curvature of each point in the point cloud and it was only related to the numbers and the operations of the points cloud.Then the volume integral invariant was calculated by the given formula,and the feature points were extracted through the K-Means clustering algorithm.The experiments show that this algorithm has higher computing efficiency,and can express the boundary feature of the clouds more precisely.
2012, 31(11): 1860-1863,1867.
Abstract:
Under the action of multiple heat sources,thermal deformation would take place in the machine tools.The correct relation positions of the tool and workpiece are broken,resulting in processing errors.In those machine parts,the spindle box coordinates with main spindle directly,the temperature increase and structure deformation of spindle box leads directly to the increase of spindle temperature and the change of tools position.In this paper,the main heat sources of spindle box,including bearing,screw,rail and motor,were analyzed and calculated.The temperature field model of the spindle box was established,using the FEM method.Combining the assembly constrain conditions of the spindle box and the entire machine,the thermal deformation model was created.The analysis result shows that using thermal symmetric structure of spindle box could effectively avoid the cylindricity error when doing cylindrical turning.At last,the simulation result was proved reliable by experiments.
Under the action of multiple heat sources,thermal deformation would take place in the machine tools.The correct relation positions of the tool and workpiece are broken,resulting in processing errors.In those machine parts,the spindle box coordinates with main spindle directly,the temperature increase and structure deformation of spindle box leads directly to the increase of spindle temperature and the change of tools position.In this paper,the main heat sources of spindle box,including bearing,screw,rail and motor,were analyzed and calculated.The temperature field model of the spindle box was established,using the FEM method.Combining the assembly constrain conditions of the spindle box and the entire machine,the thermal deformation model was created.The analysis result shows that using thermal symmetric structure of spindle box could effectively avoid the cylindricity error when doing cylindrical turning.At last,the simulation result was proved reliable by experiments.
2012, 31(11): 1864-1867.
Abstract:
A new feature combination algorithm for 3D CAD model retrieval based on the inference ability of shape feature descriptors was proposed.Initially,different feature extraction algorithms were employed to extract the corresponding feature descriptors of 3D models.Next,the inference ability of those descriptors was evaluated by using the pre-classified information in model database.Then,a feature combination frame based on Bayesian conditional probability was established for multi-feature combination.The similarity of two models was measured by the likeness of their corresponding multi-feature descriptors obtained from the feature combination.The experimental results show the effectiveness of the presented method.
A new feature combination algorithm for 3D CAD model retrieval based on the inference ability of shape feature descriptors was proposed.Initially,different feature extraction algorithms were employed to extract the corresponding feature descriptors of 3D models.Next,the inference ability of those descriptors was evaluated by using the pre-classified information in model database.Then,a feature combination frame based on Bayesian conditional probability was established for multi-feature combination.The similarity of two models was measured by the likeness of their corresponding multi-feature descriptors obtained from the feature combination.The experimental results show the effectiveness of the presented method.
2012, 31(11): 1868-1871,1875.
Abstract:
Working conditions of core in water hydraulic digital valve are quite adverse,and its material needs rather high requirements on strength and wearability.According to the requirements of digital valve components in water hydraulic transmission and from the practical standpoint,core manufactured with ceramic materials could bring its advantages of high strength,big hardness,good wearability,non-affection with corrosion.The wear case of Si3N4 ceramic core was studied by the wear-resisting experiment and the dynamic performance and the input and output characteristic simulation analysis of water hydraulic digital valve with the ceramic core was made by Matlab/Simulink software.The results show that the core manufactured with Si3N4 has high abrasion resistance and low wear rate and the water hydraulic digital valve with ceramic core has good dynamic characteristics and input/output characteristics.
Working conditions of core in water hydraulic digital valve are quite adverse,and its material needs rather high requirements on strength and wearability.According to the requirements of digital valve components in water hydraulic transmission and from the practical standpoint,core manufactured with ceramic materials could bring its advantages of high strength,big hardness,good wearability,non-affection with corrosion.The wear case of Si3N4 ceramic core was studied by the wear-resisting experiment and the dynamic performance and the input and output characteristic simulation analysis of water hydraulic digital valve with the ceramic core was made by Matlab/Simulink software.The results show that the core manufactured with Si3N4 has high abrasion resistance and low wear rate and the water hydraulic digital valve with ceramic core has good dynamic characteristics and input/output characteristics.
2012, 31(11): 1872-1875.
Abstract:
The reduction in the number of components of metamorphic mechanisms during configuration transformations was analyzed and classified into two cases: components being separated from the mechanism and components being combined.A situation of reduction in numbers of components was discussed in which adjacency is not transformed.A description method of adjacency matrix based on the situation was presented.Correctness of the method was proved by an example.
The reduction in the number of components of metamorphic mechanisms during configuration transformations was analyzed and classified into two cases: components being separated from the mechanism and components being combined.A situation of reduction in numbers of components was discussed in which adjacency is not transformed.A description method of adjacency matrix based on the situation was presented.Correctness of the method was proved by an example.
2012, 31(11): 1876-1879,1884.
Abstract:
Scheme design is the key stage of product design process.To reuse the design knowledge and the design experience implicated in the existing design,a method of extension association rule mining and reuse was proposed.This method introduced extension theory;the design knowledge was formally described with basic element;the basic element implication model of product design process was established based on its implication;a kind of improved FP-growth algorithm of association rule mining was proposed;extension association rules were mined from product case library;a knowledge reuse model based on extension association rule reasoning was established.Finally,the feasibility and efficiency of the method were verified by an example of hydraulic turbine scheme design.
Scheme design is the key stage of product design process.To reuse the design knowledge and the design experience implicated in the existing design,a method of extension association rule mining and reuse was proposed.This method introduced extension theory;the design knowledge was formally described with basic element;the basic element implication model of product design process was established based on its implication;a kind of improved FP-growth algorithm of association rule mining was proposed;extension association rules were mined from product case library;a knowledge reuse model based on extension association rule reasoning was established.Finally,the feasibility and efficiency of the method were verified by an example of hydraulic turbine scheme design.
2012, 31(11): 1880-1884.
Abstract:
Jet pipe servo valve have the advantage of high reliability and anti-polution capability.In this paper,static strength of main components of jet pipe servo valve was researched.Due to the complex structure,the loading position of oil pressures are difficult to control accurately in strength test.For that reason,a three-dimensional model of valve module was established using CATIA software and the FEA was performed on the Abaqus platform in this paper.Based on the comparative analysis of different oil pressures,we also analyzed the change of stress distribution and displacement distribution.
Jet pipe servo valve have the advantage of high reliability and anti-polution capability.In this paper,static strength of main components of jet pipe servo valve was researched.Due to the complex structure,the loading position of oil pressures are difficult to control accurately in strength test.For that reason,a three-dimensional model of valve module was established using CATIA software and the FEA was performed on the Abaqus platform in this paper.Based on the comparative analysis of different oil pressures,we also analyzed the change of stress distribution and displacement distribution.
2012, 31(11): 1885-1887,1892.
Abstract:
The scope of the optimal path problem has gradually shift from static to dynamic graphics over time,but up to now those algorithms that can be effectively applied to the dynamic optimal path is scarce.This paper presented an efficient algorithm for dynamic optimal path-IAPLA algorithm,effectively reduced the unnecessary updates and improved the convergence speed,by using the linear reinforcement learning scheme and a new update algorithm.The algorithm also used the threshold idea,propossing a control method of optimal path accuracy.Comparing IAPLA algorithm with Floyd algorithm through simulation experiments,the experimental results show there is a significant improvement in efficiency in some circumstances.
The scope of the optimal path problem has gradually shift from static to dynamic graphics over time,but up to now those algorithms that can be effectively applied to the dynamic optimal path is scarce.This paper presented an efficient algorithm for dynamic optimal path-IAPLA algorithm,effectively reduced the unnecessary updates and improved the convergence speed,by using the linear reinforcement learning scheme and a new update algorithm.The algorithm also used the threshold idea,propossing a control method of optimal path accuracy.Comparing IAPLA algorithm with Floyd algorithm through simulation experiments,the experimental results show there is a significant improvement in efficiency in some circumstances.
2012, 31(11): 1887-1892.
Abstract:
Camera calibration is an important element in the application of vision robot.A method of the exterior parameter self-calibration was presented for the robot vision system with a fixed camera.The basic principle of the proposed calibration method is to control the robot end undergo three sets tiny motions along three axes of the base frame respectively,then use the image information grabbed by the calibrated camera to calculate the exterior parameters based on the relationship between the camera matrix and the matrix of the robot end to the robot base frame.Moreover,taking into account the effect of measurement and calculation noises,an orthonormalizing adjustment was also given to correctct the calibrated rotation matrix's orthonormality and error.The method is proved to have a good performance of accuracy and robustness,and is feasible of on-line camera calibration with some experiments on synthetic and real image.
Camera calibration is an important element in the application of vision robot.A method of the exterior parameter self-calibration was presented for the robot vision system with a fixed camera.The basic principle of the proposed calibration method is to control the robot end undergo three sets tiny motions along three axes of the base frame respectively,then use the image information grabbed by the calibrated camera to calculate the exterior parameters based on the relationship between the camera matrix and the matrix of the robot end to the robot base frame.Moreover,taking into account the effect of measurement and calculation noises,an orthonormalizing adjustment was also given to correctct the calibrated rotation matrix's orthonormality and error.The method is proved to have a good performance of accuracy and robustness,and is feasible of on-line camera calibration with some experiments on synthetic and real image.
