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RSS2013 Vol. 32, No. 9
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2013, 32(9): 1249-1253.
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Abstract:
The dynamics numerical simulation is more and more important in the product design of flexible net. The modeling and dynamical characteristic of rope element are discussed in this paper. Based on the finite element method,a new method is proposed to simulate flexible net with seatbelt element in LS-DYNA. The key points of modeling in the method are described,including definition of elements and material character,load setting,initial condition setting and the processing of contact relationship. The method is verified by a simulation for the deployment process of flexible net. The result shows that it is effective and robust to simulate of net deployment with LS-DYNA seatbelt elements,and the contact relationship between flexible net and entity can be realistically simulated with "nodes to surface" contact definition.
The dynamics numerical simulation is more and more important in the product design of flexible net. The modeling and dynamical characteristic of rope element are discussed in this paper. Based on the finite element method,a new method is proposed to simulate flexible net with seatbelt element in LS-DYNA. The key points of modeling in the method are described,including definition of elements and material character,load setting,initial condition setting and the processing of contact relationship. The method is verified by a simulation for the deployment process of flexible net. The result shows that it is effective and robust to simulate of net deployment with LS-DYNA seatbelt elements,and the contact relationship between flexible net and entity can be realistically simulated with "nodes to surface" contact definition.
2013, 32(9): 1254-1258.
Abstract:
Based on the characteristics of high-speed turbopump system,taking into account of the seals,thrust bearing,axial balancing device and other tribological components,we conducted the integrated modeling including the rotor,the thrust bearings and other components. Numerical simulations for the performance of a liquid hydrogen high-speed turbopump rotor dynamics were performed and the results showed that when taking into account the torque stiffness of the seal,thrust bearings,balance disc and superconducting tilting pad,the first critical speed of the system was increased by 25%,instability speed was increased by 50%,thus,it provides a new idea for high-speed turbopump rotor to improving the stability of the rotor system. To further enhance the stability of the rotor system,we introduced the superconducting tilting pad in the bearing and discussed the integrated modeling method for the rotor system with this attachment.
Based on the characteristics of high-speed turbopump system,taking into account of the seals,thrust bearing,axial balancing device and other tribological components,we conducted the integrated modeling including the rotor,the thrust bearings and other components. Numerical simulations for the performance of a liquid hydrogen high-speed turbopump rotor dynamics were performed and the results showed that when taking into account the torque stiffness of the seal,thrust bearings,balance disc and superconducting tilting pad,the first critical speed of the system was increased by 25%,instability speed was increased by 50%,thus,it provides a new idea for high-speed turbopump rotor to improving the stability of the rotor system. To further enhance the stability of the rotor system,we introduced the superconducting tilting pad in the bearing and discussed the integrated modeling method for the rotor system with this attachment.
2013, 32(9): 1259-1262.
Abstract:
The dynamical equation and state equation of gear transmission system are established according to Newton's principle. The complex dynamics characters of gear transmission system are studied. The bifurcation characteristic of nonlinear system is studied by the bifurcation diagram,phase portrait,time course diagram and Poincar閙ap. The method to control chaos by linear feedback controller is developed to guide chaotic motions towards regular motions. Numerical simulation shows that with the increasing of gear pair meshing damping,gear transmission system will be from chaotic motions to the periodic motions by inverse doubling bifurcation,the effectiveness and feasibility of strategy to get rid of chaos by stabilizing the related unstable periodic orbit.
The dynamical equation and state equation of gear transmission system are established according to Newton's principle. The complex dynamics characters of gear transmission system are studied. The bifurcation characteristic of nonlinear system is studied by the bifurcation diagram,phase portrait,time course diagram and Poincar閙ap. The method to control chaos by linear feedback controller is developed to guide chaotic motions towards regular motions. Numerical simulation shows that with the increasing of gear pair meshing damping,gear transmission system will be from chaotic motions to the periodic motions by inverse doubling bifurcation,the effectiveness and feasibility of strategy to get rid of chaos by stabilizing the related unstable periodic orbit.
2013, 32(9): 1263-1266.
Abstract:
Dry friction platform damper system can be used to reduce the blade vibration amplitude. When the normal load between the contacts is becoming larger,dry friction damper will lose its damping characteristic. By considering this issue,an improved model is present. Based on the improved friction model,the damping characteristic of systems with platform damper is simulated with first-order Harmonic Balance Method( HBM). The influence of damper stiffness coefficient,normal pressure of the contacts and the external excitation amplitude on vibration reduction is studied. Simulation results show that the improved model can better reflect the dynamic characteristics of the system.
Dry friction platform damper system can be used to reduce the blade vibration amplitude. When the normal load between the contacts is becoming larger,dry friction damper will lose its damping characteristic. By considering this issue,an improved model is present. Based on the improved friction model,the damping characteristic of systems with platform damper is simulated with first-order Harmonic Balance Method( HBM). The influence of damper stiffness coefficient,normal pressure of the contacts and the external excitation amplitude on vibration reduction is studied. Simulation results show that the improved model can better reflect the dynamic characteristics of the system.
2013, 32(9): 1267-1271.
Abstract:
Dynamic characteristics of the vehicle frame were analyzed using finite element modal analysis theory and the rationality was proved by the corresponding modal test. Bending and torsional stiffness was solved with the proved model. Sensitivity analysis was conducted to choose the effective design variables. A optimizationdesign model for lightweight vehicle frame was built with constraint for its stiffness and the first-order modal frequency.Sampling points were obtained by using Latin Hypercube experimental design method; approximate models for responses were built by using radial basis functions,genetic algorithm was used to optimize the approximation model.The optimized parameters were substituted into the true model,the results showed that at with the requirements of stiffness and the first-order modal frequency the total mass of frame was decreased by 18. 37kg.
Dynamic characteristics of the vehicle frame were analyzed using finite element modal analysis theory and the rationality was proved by the corresponding modal test. Bending and torsional stiffness was solved with the proved model. Sensitivity analysis was conducted to choose the effective design variables. A optimizationdesign model for lightweight vehicle frame was built with constraint for its stiffness and the first-order modal frequency.Sampling points were obtained by using Latin Hypercube experimental design method; approximate models for responses were built by using radial basis functions,genetic algorithm was used to optimize the approximation model.The optimized parameters were substituted into the true model,the results showed that at with the requirements of stiffness and the first-order modal frequency the total mass of frame was decreased by 18. 37kg.
2013, 32(9): 1272-1275.
Abstract:
The UAV's( Unmanned Aerial Vehicle) weight analysis is a key segment in the preliminary design of the UAV. The paper deduced the UAV's structural weight formulas through the statistics of UAV's structural weight data combined with experiments of experts and engineering practice. Then the author analyzed a HALE( High Altitude Long Endurance) UAV' s structural weight and the results showed the merits from these formulas to analyze the UAV's structural weight in preliminary design phase is sufficient and credible. Lastly,the author deduced the impact equations based upon these equations of structural weight calculation,using these equations to analyze the impact of the parameters on the weight of the UAV and showed a better result compared with the practical result. I believe we should pay more attention to these parameters and may also notice other factors contributed to the weight in the design of the UAVs.
The UAV's( Unmanned Aerial Vehicle) weight analysis is a key segment in the preliminary design of the UAV. The paper deduced the UAV's structural weight formulas through the statistics of UAV's structural weight data combined with experiments of experts and engineering practice. Then the author analyzed a HALE( High Altitude Long Endurance) UAV' s structural weight and the results showed the merits from these formulas to analyze the UAV's structural weight in preliminary design phase is sufficient and credible. Lastly,the author deduced the impact equations based upon these equations of structural weight calculation,using these equations to analyze the impact of the parameters on the weight of the UAV and showed a better result compared with the practical result. I believe we should pay more attention to these parameters and may also notice other factors contributed to the weight in the design of the UAVs.
2013, 32(9): 1276-1280.
Abstract:
Based on the finite element method,commercial finite element analysis software MSC. Patran/Nastran is used to do some research on bird strike damage of laminated composite plate. The laminated composite plate dam-aged will be repaired with a stepped repair way. The damage model and the damaged stress of repaired areas of laminated composite plate with different repairing methods,such as changing the layer order and ladder number,are studied in simulation. This research can provide certain theoretical basis to the impact damage on engineering.
Based on the finite element method,commercial finite element analysis software MSC. Patran/Nastran is used to do some research on bird strike damage of laminated composite plate. The laminated composite plate dam-aged will be repaired with a stepped repair way. The damage model and the damaged stress of repaired areas of laminated composite plate with different repairing methods,such as changing the layer order and ladder number,are studied in simulation. This research can provide certain theoretical basis to the impact damage on engineering.
2013, 32(9): 1281-1286.
Abstract:
The effects of reinforcement's volume fraction and size,heat-treatment condition and cooling condition on the high-speed machinability were investigated when milling SiCp/2009Al composites at the cutting speed of 1200 m/ min using PCD tools. The results show that decreasing the volume fraction or using coolant will improve the high-speed milling machinability. When cutting the heat-treated composites,the machined surface is improved significantly but the increasing of cutting forces,decreasing of tool life and the tendency of producing saw-toothed chip are also evident. Keeping the volume fraction unchanged and increasing the average size of reinforcement will reduce the cutting forces and cutting temperature and prolong the tool life,but the machined surface quality will be decreased simultaneously.
The effects of reinforcement's volume fraction and size,heat-treatment condition and cooling condition on the high-speed machinability were investigated when milling SiCp/2009Al composites at the cutting speed of 1200 m/ min using PCD tools. The results show that decreasing the volume fraction or using coolant will improve the high-speed milling machinability. When cutting the heat-treated composites,the machined surface is improved significantly but the increasing of cutting forces,decreasing of tool life and the tendency of producing saw-toothed chip are also evident. Keeping the volume fraction unchanged and increasing the average size of reinforcement will reduce the cutting forces and cutting temperature and prolong the tool life,but the machined surface quality will be decreased simultaneously.
2013, 32(9): 1287-1290.
Abstract:
Pulsating changes of cabin pressure arisen in some aircrafts that use CYT-xx pressure regulating systems.The dynamic characteristics of proportional pressure modulating suit are studied in order to eliminate the possible unstable factor that may be caused by this suit. The present study introduces the functional components of aircraft cabin pressure regulating system to describe the structure,working principle and static characterization of proportional modulating suit. And after analyzing the external character of the moving parts and the physical feature of polymer,it is found that the stickiness of the material is essential to the stability of the suit. On this basis,a second order dynamic model is build for the suit. According to the special demand of the cabin pressure regulating system,it points out that the requirement of the stable operating is ξ≥1. Based on theoretical deduction,it comes to conclusion that with the premise of satisfying stability requirement,a smaller mass of movable part and bigger equivalent elastic coefficient k is useful to shorten the reaction time. A simulation model is built according to the real parameter of the suit and the simulating results agree well with the experimental data.
Pulsating changes of cabin pressure arisen in some aircrafts that use CYT-xx pressure regulating systems.The dynamic characteristics of proportional pressure modulating suit are studied in order to eliminate the possible unstable factor that may be caused by this suit. The present study introduces the functional components of aircraft cabin pressure regulating system to describe the structure,working principle and static characterization of proportional modulating suit. And after analyzing the external character of the moving parts and the physical feature of polymer,it is found that the stickiness of the material is essential to the stability of the suit. On this basis,a second order dynamic model is build for the suit. According to the special demand of the cabin pressure regulating system,it points out that the requirement of the stable operating is ξ≥1. Based on theoretical deduction,it comes to conclusion that with the premise of satisfying stability requirement,a smaller mass of movable part and bigger equivalent elastic coefficient k is useful to shorten the reaction time. A simulation model is built according to the real parameter of the suit and the simulating results agree well with the experimental data.
2013, 32(9): 1291-1297.
Abstract:
As all-electric aircraft has many advantages,the all-electric aircraft nose wheel steering system would be developed. Aiming at the control demand of nose wheel steering system,based on the basic principles of nose wheel steering system and the design technique of mechanotronics,an all-electric aircraft nose wheel steering system is designed to meet the demand for operation control in nose wheel steering system,the system is composed of a nose wheel steering mechanism of turbine worm and a control servo system of fly-by-wire having both steering and antishimmy function. The simulation model of the system is established to perform the optimization of dynamic properties and dynamic simulation analysis for the verification of its steering and shimmy damping function. The results indicate that the nose wheel steering system is reasonable and validated,and it can meet the requirements of the general project.
As all-electric aircraft has many advantages,the all-electric aircraft nose wheel steering system would be developed. Aiming at the control demand of nose wheel steering system,based on the basic principles of nose wheel steering system and the design technique of mechanotronics,an all-electric aircraft nose wheel steering system is designed to meet the demand for operation control in nose wheel steering system,the system is composed of a nose wheel steering mechanism of turbine worm and a control servo system of fly-by-wire having both steering and antishimmy function. The simulation model of the system is established to perform the optimization of dynamic properties and dynamic simulation analysis for the verification of its steering and shimmy damping function. The results indicate that the nose wheel steering system is reasonable and validated,and it can meet the requirements of the general project.
2013, 32(9): 1298-1302.
Abstract:
Survival ability of a gear transmission system in helicopter after Loss-Of-Lubrication( LOL) is greatly dependent on the transient temperature fields of the systems. And the gearbox reversing bevel gear transmission system is extremely easy to failure after LOL because of its high rotate speed and power. So the transient thermal analysis of a helicopter gearbox reversing bevel gear transmission system is needed while design a new model. To research its transient temperature fields,a reversing bevel gear transmission system in gearbox is researched in this paper,and the calculation model of temperature field is established based on the thermal network. The tim-evariance characteristics of thermal physical parameters,such as viscosity,thermal conductivity are considered in this model. Numerical simulations are performed to calculate the steady temperature field and transient temperature field and the results of steady state temperature field in the transmission system are used as initial values of the transient temperature fields. The results agree well with the theoretical predictions.
Survival ability of a gear transmission system in helicopter after Loss-Of-Lubrication( LOL) is greatly dependent on the transient temperature fields of the systems. And the gearbox reversing bevel gear transmission system is extremely easy to failure after LOL because of its high rotate speed and power. So the transient thermal analysis of a helicopter gearbox reversing bevel gear transmission system is needed while design a new model. To research its transient temperature fields,a reversing bevel gear transmission system in gearbox is researched in this paper,and the calculation model of temperature field is established based on the thermal network. The tim-evariance characteristics of thermal physical parameters,such as viscosity,thermal conductivity are considered in this model. Numerical simulations are performed to calculate the steady temperature field and transient temperature field and the results of steady state temperature field in the transmission system are used as initial values of the transient temperature fields. The results agree well with the theoretical predictions.
2013, 32(9): 1303-1306.
Abstract:
In the grinding process,a portion of the coolant lubricant is accelerated into the contact zone by grinding wheel. Because of the wedge effect between grinding wheel and work-piece in the contact zone,hydrodynamic pressure is generated,which influences the grinding results. So it is necessary to study hydrodynamic pressure of the coolant. In this paper,a new model for the hydrodynamic pressure of coolant is presented. The simulation about distributing of hydrodynamic pressure was carried out. The results show that the hydrodynamic pressure is affected by grinding wheel velocity and the minimum gap between grinding wheel and work-piece. On the other hand,it will be affected by the specification of the grinding wheel. Furthermore the experiment was fulfiled. The comparison between the experimental and the simulation results shows that the present model for hydrodynamic pressure and the simulation results are correct.
In the grinding process,a portion of the coolant lubricant is accelerated into the contact zone by grinding wheel. Because of the wedge effect between grinding wheel and work-piece in the contact zone,hydrodynamic pressure is generated,which influences the grinding results. So it is necessary to study hydrodynamic pressure of the coolant. In this paper,a new model for the hydrodynamic pressure of coolant is presented. The simulation about distributing of hydrodynamic pressure was carried out. The results show that the hydrodynamic pressure is affected by grinding wheel velocity and the minimum gap between grinding wheel and work-piece. On the other hand,it will be affected by the specification of the grinding wheel. Furthermore the experiment was fulfiled. The comparison between the experimental and the simulation results shows that the present model for hydrodynamic pressure and the simulation results are correct.
2013, 32(9): 1307-1313.
Abstract:
The phenomenon of vibration in high-speed rolling process has been recognized as a major restriction to the improvement of strip quality and rolling productivity. Based on the summary and analysis of research works at home and abroad,the reasons to lead vibration in rolling mills were analyzed in this paper. The dynamic model of rolling mills as well as its control strategy was introduced,and especially the significance of coupling effects on vibration mechanism and control method has been illustrated. Finally,study direction and emphasis in the future are put forward according to the problems and difficulties existing in current researches.
The phenomenon of vibration in high-speed rolling process has been recognized as a major restriction to the improvement of strip quality and rolling productivity. Based on the summary and analysis of research works at home and abroad,the reasons to lead vibration in rolling mills were analyzed in this paper. The dynamic model of rolling mills as well as its control strategy was introduced,and especially the significance of coupling effects on vibration mechanism and control method has been illustrated. Finally,study direction and emphasis in the future are put forward according to the problems and difficulties existing in current researches.
2013, 32(9): 1314-1317.
Abstract:
The starting safety performance of internal combustion engines is an important indicator of safety requirements. As to the recoil starting equipment,many researchers in China adopts the equivalent security requirements of international standards and has clear numerical requirements to test the starting rope's maximum force. How to determine the force is still a pending problem. In this paper,the influencing factors in the starting resistance torque of an internal combustion engine is analyzed; the calculation methods of inertia resistance moment,friction resistance moment and compression resistance moment is proposed; the variation of the calculated value that caused by the main influencing factors of starting performance is discussed. The comparison between the results and the relevant test data,a calculation method is drawn and verified to measure the rope force with the use of starting resistance torque. For a 186 FA diesel engine and 190F,168F,152F gasoline engines,the rope force of recoil starting equipment is calculated and analyzed,and the design and inspection of products in the industry of internal combustion engine will be based on the results of the calculation and analysis.
The starting safety performance of internal combustion engines is an important indicator of safety requirements. As to the recoil starting equipment,many researchers in China adopts the equivalent security requirements of international standards and has clear numerical requirements to test the starting rope's maximum force. How to determine the force is still a pending problem. In this paper,the influencing factors in the starting resistance torque of an internal combustion engine is analyzed; the calculation methods of inertia resistance moment,friction resistance moment and compression resistance moment is proposed; the variation of the calculated value that caused by the main influencing factors of starting performance is discussed. The comparison between the results and the relevant test data,a calculation method is drawn and verified to measure the rope force with the use of starting resistance torque. For a 186 FA diesel engine and 190F,168F,152F gasoline engines,the rope force of recoil starting equipment is calculated and analyzed,and the design and inspection of products in the industry of internal combustion engine will be based on the results of the calculation and analysis.
2013, 32(9): 1318-1321.
Abstract:
The sticking process is one of the key techniques in the continuous production process of paper-based friction plate,and the performance and productivity of the paper-based friction plate are greatly affected by the advantages and disadvantages of sticking process. In this paper,on the basis of the appropriate sticking process selection,an indexing and reset device applied on the sticking process of a type of clutch was designed by studying the sticking technology in its production process,and the key techniques of substrate positioning fixture design,the implementation of the indexing and reset action related to the device were also studied. The device can achieve the role of positioning,indexing and reset of the substrate simultaneously,and meets the use requirements.
The sticking process is one of the key techniques in the continuous production process of paper-based friction plate,and the performance and productivity of the paper-based friction plate are greatly affected by the advantages and disadvantages of sticking process. In this paper,on the basis of the appropriate sticking process selection,an indexing and reset device applied on the sticking process of a type of clutch was designed by studying the sticking technology in its production process,and the key techniques of substrate positioning fixture design,the implementation of the indexing and reset action related to the device were also studied. The device can achieve the role of positioning,indexing and reset of the substrate simultaneously,and meets the use requirements.
2013, 32(9): 1322-1326.
Abstract:
In order to meet the high thrust-to-weight ratio of aero-engine,all parts have a very strict quality requirements. Disks are the rotor components of the engine,so its structural design is very significant. According to the equivalent strength theory,the possibility of the equivlent strength disk exists and its design method are found. And the theoretical knowledge of the structueal design and optimization method are mastered by studying the finite element method. An optimum design model is established and main optimum design variables are chosen for disk based on ANSYS optimization platform. And then the design of an aeroengine compressor disk was optimized by this method. On the same stress conditions,the quality of the optimization disk was reduced by 10. 27% than the quality of the traditional method design.
In order to meet the high thrust-to-weight ratio of aero-engine,all parts have a very strict quality requirements. Disks are the rotor components of the engine,so its structural design is very significant. According to the equivalent strength theory,the possibility of the equivlent strength disk exists and its design method are found. And the theoretical knowledge of the structueal design and optimization method are mastered by studying the finite element method. An optimum design model is established and main optimum design variables are chosen for disk based on ANSYS optimization platform. And then the design of an aeroengine compressor disk was optimized by this method. On the same stress conditions,the quality of the optimization disk was reduced by 10. 27% than the quality of the traditional method design.
2013, 32(9): 1327-1331.
Abstract:
A method for automobile face design based on Quartic B閦ier curves with shape parameters is proposed in this paper,which describes the automobile face contours with one Quartic B閦ier curve. Firstly,a Quartic B閦ier curve with control points is created and adjusted in a plane; then the curve is projected on the automobile's surface;finally,the automobile's surface is trimmed and it forms the final shape contours of the automobile face. This method,based on the generation and splicing principle of Quartic B閦ier curve,can quickly modify the curve by global or partial adjustment and obtain many design solutions.
A method for automobile face design based on Quartic B閦ier curves with shape parameters is proposed in this paper,which describes the automobile face contours with one Quartic B閦ier curve. Firstly,a Quartic B閦ier curve with control points is created and adjusted in a plane; then the curve is projected on the automobile's surface;finally,the automobile's surface is trimmed and it forms the final shape contours of the automobile face. This method,based on the generation and splicing principle of Quartic B閦ier curve,can quickly modify the curve by global or partial adjustment and obtain many design solutions.
2013, 32(9): 1332-1336.
Abstract:
Fatigue resistance is one of the key factors of the connection quality assessment for aircraft riveted structure,which directly influence the security of aircraft service. Aiming at single riveted structure in this paper,the height of driven rivet head is selected as the control variable,which is one of parameters of riveted process. To study the effect of process on fatigue resistance,fatigue experiments and the finite element method are used to analyze the deformation and stress distribution of rivet hole in detail. A method of height interval estimation of riveted head is proposed based on stress distribution in hole and fatigue experiment. The result shows that the height of riveted head has significant effect on stress distribution in the interface between rivet and hole. The fatigue resistance of riveted structure is effectively improved by controlling the height of driven rivet head.
Fatigue resistance is one of the key factors of the connection quality assessment for aircraft riveted structure,which directly influence the security of aircraft service. Aiming at single riveted structure in this paper,the height of driven rivet head is selected as the control variable,which is one of parameters of riveted process. To study the effect of process on fatigue resistance,fatigue experiments and the finite element method are used to analyze the deformation and stress distribution of rivet hole in detail. A method of height interval estimation of riveted head is proposed based on stress distribution in hole and fatigue experiment. The result shows that the height of riveted head has significant effect on stress distribution in the interface between rivet and hole. The fatigue resistance of riveted structure is effectively improved by controlling the height of driven rivet head.
2013, 32(9): 1337-1341.
Abstract:
The inverse dynamics of the flexible multibody system is studied based on the Spatial Operator Algebra theory,and the realization of the generalized mass procedure is built in the environment of Matahematic6. 0 software. The high effective stepping method can be used to compute forward and reward dynamics,and it is the important factor linking rotate force and rotating acceleration,and has a simple math expression and a clear physical meaning. The software structure of the generalized mass and inverse dynamics is built and the dynamics simulation model for flexible multibody system is realized based on the integrated procedure and Mathematic6. 0. According to the present analysis,the example of star generalized mass is studied,and correctness and validity is verified by computed examples.
The inverse dynamics of the flexible multibody system is studied based on the Spatial Operator Algebra theory,and the realization of the generalized mass procedure is built in the environment of Matahematic6. 0 software. The high effective stepping method can be used to compute forward and reward dynamics,and it is the important factor linking rotate force and rotating acceleration,and has a simple math expression and a clear physical meaning. The software structure of the generalized mass and inverse dynamics is built and the dynamics simulation model for flexible multibody system is realized based on the integrated procedure and Mathematic6. 0. According to the present analysis,the example of star generalized mass is studied,and correctness and validity is verified by computed examples.
2013, 32(9): 1342-1347.
Abstract:
In order to ensure the machining accuracy and cutting efficiency of a machine center,taking the column of the machine center as an example,a multi-objective optimization design method in lightweight design for machining center is proposed in this paper,based on the mass and first natural frequency objectives. First of all,the element analysis software-ABAQUS is utilized to analyze the static and dynamic performances of the column. And then according to the column structure,the key factors affecting the first natural frequency and the mass should be extracted. Through the uniform design,MATLAB is used to establish the multiple linear regression equations between the goals and the key factors. At the same time,sensitivity analysis is conducted to find out the sensitivity factors. The target's second order response surface mathematical model is built between the goals and sensitive factors by using the response surface method,and then the optimization model of column is set up with the purpose of reducing the mass and improving the natural frequency. Finally,the MATLAB is applied to optimize the mathematical model. As a conclusion,the mass is reduced by13. 6% under the condition of the improvement of the natural frequency.
In order to ensure the machining accuracy and cutting efficiency of a machine center,taking the column of the machine center as an example,a multi-objective optimization design method in lightweight design for machining center is proposed in this paper,based on the mass and first natural frequency objectives. First of all,the element analysis software-ABAQUS is utilized to analyze the static and dynamic performances of the column. And then according to the column structure,the key factors affecting the first natural frequency and the mass should be extracted. Through the uniform design,MATLAB is used to establish the multiple linear regression equations between the goals and the key factors. At the same time,sensitivity analysis is conducted to find out the sensitivity factors. The target's second order response surface mathematical model is built between the goals and sensitive factors by using the response surface method,and then the optimization model of column is set up with the purpose of reducing the mass and improving the natural frequency. Finally,the MATLAB is applied to optimize the mathematical model. As a conclusion,the mass is reduced by13. 6% under the condition of the improvement of the natural frequency.
2013, 32(9): 1348-1352.
Abstract:
This paper deals with the hand controller used in single crystal furnace,the aim is to research on ergonomics application of same kind of hand-held devices. The agreeableness of the product and customer need is the prime considerations. Palm structure,some key sizes,appearance design,color design are analyzed based on ergonomics theory. Specific and effective design principles for hand-held device are put forward and applied on design.The aim is comfortable operation,simple recognition and safe use. Customer evaluation shows that the design based on ergonomics modifies the bad factors of the original product and obtains a good result.
This paper deals with the hand controller used in single crystal furnace,the aim is to research on ergonomics application of same kind of hand-held devices. The agreeableness of the product and customer need is the prime considerations. Palm structure,some key sizes,appearance design,color design are analyzed based on ergonomics theory. Specific and effective design principles for hand-held device are put forward and applied on design.The aim is comfortable operation,simple recognition and safe use. Customer evaluation shows that the design based on ergonomics modifies the bad factors of the original product and obtains a good result.
2013, 32(9): 1353-1357.
Abstract:
In order to study the effect of the dynamic process on the stability of aircraft engine,one-dimensional model based on component matching and time marching method were presented; the dynamic process simulation model for a two spool mixed flow turbofan was established. According to the stability of the assessment requirements,acceleration,deceleration,afterburner light-on and light-off processes were simulated and analyzed. The simuation results show that,acceleration process has a great impact on the stability of high pressure compressor,the maximum stability margin loss was 16. 1%,comparing with the steady-state; Deceleration process has a great impact on the stability of fan,the maximum stability margin loss was 13. 6%; After burner light-on and light-off processes have a great impact on the stability of fan,the maximum stability margin loss were 11. 6% and 2. 8%.
In order to study the effect of the dynamic process on the stability of aircraft engine,one-dimensional model based on component matching and time marching method were presented; the dynamic process simulation model for a two spool mixed flow turbofan was established. According to the stability of the assessment requirements,acceleration,deceleration,afterburner light-on and light-off processes were simulated and analyzed. The simuation results show that,acceleration process has a great impact on the stability of high pressure compressor,the maximum stability margin loss was 16. 1%,comparing with the steady-state; Deceleration process has a great impact on the stability of fan,the maximum stability margin loss was 13. 6%; After burner light-on and light-off processes have a great impact on the stability of fan,the maximum stability margin loss were 11. 6% and 2. 8%.
2013, 32(9): 1358-1362.
Abstract:
In this paper the mechanical properties of the cracked structures are investigated using the equivalent medium theory. Based on the definition of the surface damaged layer,the two-material composite beam is used to model the cracked beam. The differential equation of the deflection curve of the cracked beam is deduced. The effects of the damaged layer on the bending deformation are studied. The relation among the beam deflection,the thickness of the damaged layer and the equivalent elastic modulus of the damaged part is obtained. In addition,the influence of the damaged layer thickness modulus on the beam stiffness is also evaluated. The numerical results reveal that the deflection of the beam will increase and the stiffness of the beam will decrease as the thickness of the damaged layer increases or the elastic modulus of the damaged layer decreases. When the thickness of the damaged layer is larger than 3% of the thickness of the beam,the influence of the damaged layer on the deflection and stiffness of the beam are so obviously that will affect the accuracy during the manufacturing process significantly.
In this paper the mechanical properties of the cracked structures are investigated using the equivalent medium theory. Based on the definition of the surface damaged layer,the two-material composite beam is used to model the cracked beam. The differential equation of the deflection curve of the cracked beam is deduced. The effects of the damaged layer on the bending deformation are studied. The relation among the beam deflection,the thickness of the damaged layer and the equivalent elastic modulus of the damaged part is obtained. In addition,the influence of the damaged layer thickness modulus on the beam stiffness is also evaluated. The numerical results reveal that the deflection of the beam will increase and the stiffness of the beam will decrease as the thickness of the damaged layer increases or the elastic modulus of the damaged layer decreases. When the thickness of the damaged layer is larger than 3% of the thickness of the beam,the influence of the damaged layer on the deflection and stiffness of the beam are so obviously that will affect the accuracy during the manufacturing process significantly.
2013, 32(9): 1363-1367.
Abstract:
To select optimally the technology parameters of cold roll-beating to decrease flaws and improve the quality of the finished parts,the common flaws of strip in cold roll-beating are studied in this paper. The principle of slab cold roll-beating forming is discussed and the factors affecting slab cold roll-beating and strip occurring are analyzed. Theoretical analysis of stripe flaw is carried out and expression of relation between the characterization parameters( vertical corrugated roughness and stripe interval) of stripe and related technology parameters is obtained.Effects of technology parameters such as feed and rotating speed of the roller on vertical corrugated roughness of the stripe is analyzed. Forming experiments are carried out with self-developed cold roll-beating experimental equipment and the height of stripe is measured to verify the correctness of theoretical analysis above.
To select optimally the technology parameters of cold roll-beating to decrease flaws and improve the quality of the finished parts,the common flaws of strip in cold roll-beating are studied in this paper. The principle of slab cold roll-beating forming is discussed and the factors affecting slab cold roll-beating and strip occurring are analyzed. Theoretical analysis of stripe flaw is carried out and expression of relation between the characterization parameters( vertical corrugated roughness and stripe interval) of stripe and related technology parameters is obtained.Effects of technology parameters such as feed and rotating speed of the roller on vertical corrugated roughness of the stripe is analyzed. Forming experiments are carried out with self-developed cold roll-beating experimental equipment and the height of stripe is measured to verify the correctness of theoretical analysis above.
2013, 32(9): 1368-1373.
Abstract:
To anlyse the compaction process of vibrating roller more accurately,a new 6-DOF system dynamic model was built under the coupling operating condition of intellectual vibratory roller considering the qualities of soilmass and was applied on a type of intellectual vibratory roller' dynamic analysis. On the basis of analysis results,the design parameter optimization of the vibratory roller is studied in this paper,and the optimum working parameters was achived. It has been proved that by practice that the model realizes the effective control of intellectual vibratory roller in the process of compaction,advances the density and compaction efficiency in compacting process,and improves comfortabilityg of the complete machine.
To anlyse the compaction process of vibrating roller more accurately,a new 6-DOF system dynamic model was built under the coupling operating condition of intellectual vibratory roller considering the qualities of soilmass and was applied on a type of intellectual vibratory roller' dynamic analysis. On the basis of analysis results,the design parameter optimization of the vibratory roller is studied in this paper,and the optimum working parameters was achived. It has been proved that by practice that the model realizes the effective control of intellectual vibratory roller in the process of compaction,advances the density and compaction efficiency in compacting process,and improves comfortabilityg of the complete machine.
2013, 32(9): 1374-1377.
Abstract:
In order to obtain a reasonable evaluation method as design scheme evaluation goal of transfer case,three Time-sharing 4WD Vehicle transfer cases are selected as examples to describe the basic principle and establish model construction steps of multiple-factor fuzzy evaluation method. According to the cross-country capability and ride-ability requirements of cars,in conditions of ensuring performance and performance stability,parts intensity and rigidity reliability of transfer case,multiple-objective evaluation function of transfer case is established based on the factors of gear volume,in-situ started acceleration time and max speed under time-sharing 4WD conditions; and then the fuzzy evaluation method of multiple-factor is applied to evaluate these design proposals. Evaluation results show that the application of fuzzy evaluation method of multiple-factor can make a reasonable effective evaluation.
In order to obtain a reasonable evaluation method as design scheme evaluation goal of transfer case,three Time-sharing 4WD Vehicle transfer cases are selected as examples to describe the basic principle and establish model construction steps of multiple-factor fuzzy evaluation method. According to the cross-country capability and ride-ability requirements of cars,in conditions of ensuring performance and performance stability,parts intensity and rigidity reliability of transfer case,multiple-objective evaluation function of transfer case is established based on the factors of gear volume,in-situ started acceleration time and max speed under time-sharing 4WD conditions; and then the fuzzy evaluation method of multiple-factor is applied to evaluate these design proposals. Evaluation results show that the application of fuzzy evaluation method of multiple-factor can make a reasonable effective evaluation.
2013, 32(9): 1378-1384.
Abstract:
The forward displacement analysis of spatial parallel mechanisms is to solve the position and orientation of the platform,which is confirmed by the length of the paralleled links. Forward position analysis of the 6-5 platform parallel mechanism is studied. The mathematics model and constrain equations are set up by using direction cosine matrix. The problem of forward analysis is reduced to a 20th degree polynomial equation in a single unknown by a series of algebraic derivation and resultant elimination,then 40 groups of solutions are obtained. Numerical example confirms that the numbers of analytical solutions for 6-5 platform parallel mechanism are 40.
The forward displacement analysis of spatial parallel mechanisms is to solve the position and orientation of the platform,which is confirmed by the length of the paralleled links. Forward position analysis of the 6-5 platform parallel mechanism is studied. The mathematics model and constrain equations are set up by using direction cosine matrix. The problem of forward analysis is reduced to a 20th degree polynomial equation in a single unknown by a series of algebraic derivation and resultant elimination,then 40 groups of solutions are obtained. Numerical example confirms that the numbers of analytical solutions for 6-5 platform parallel mechanism are 40.
2013, 32(9): 1385-1388.
Abstract:
To improve the processing efficiency of the wire cut electronic discharge machining( WEDM),the effect of the machining gap on the processing efficiency was analyzed. The lateral vibration mathematical model of the wire electrode was established,the influence of various processing parameters on the wire electrode vibration amplitude and machining gap was studied. Then,taking a molybdenum wire with 1 mm diameter as the experimental workpiece,the processing experiment was conducted to explore the influence of the parameters,such as the peak current,the pulse width and the pulse frequency,on the vibration amplitude of wire electrode. The results show that the vibration model is correct,and it can provide a reference for optimizing the WEDM machining gap and improve the processing efficiency.
To improve the processing efficiency of the wire cut electronic discharge machining( WEDM),the effect of the machining gap on the processing efficiency was analyzed. The lateral vibration mathematical model of the wire electrode was established,the influence of various processing parameters on the wire electrode vibration amplitude and machining gap was studied. Then,taking a molybdenum wire with 1 mm diameter as the experimental workpiece,the processing experiment was conducted to explore the influence of the parameters,such as the peak current,the pulse width and the pulse frequency,on the vibration amplitude of wire electrode. The results show that the vibration model is correct,and it can provide a reference for optimizing the WEDM machining gap and improve the processing efficiency.
2013, 32(9): 1389-1393.
Abstract:
The performance of a clamping system will directly affect the quality of injection-molding products. In the past,the performance of clamping units was optimized by using the single-objective optimization method or traditional multi-objective optimization method,however,the results were not ideal. In this paper,firstly,the mathematical model of the clamping system is established,and a sensitivity analysis method is adopted to determine significant factors from various parameters affecting of the objective functions as design variables,then the NSGAII is applied to optimize the ratio of force amplification and the smoothness of moving-platen speed. Finally,the comparison between the results before and after optimization in ADAMS shows that the ratio of force amplification has increased,and the motion smoothness of moving platen improves well.
The performance of a clamping system will directly affect the quality of injection-molding products. In the past,the performance of clamping units was optimized by using the single-objective optimization method or traditional multi-objective optimization method,however,the results were not ideal. In this paper,firstly,the mathematical model of the clamping system is established,and a sensitivity analysis method is adopted to determine significant factors from various parameters affecting of the objective functions as design variables,then the NSGAII is applied to optimize the ratio of force amplification and the smoothness of moving-platen speed. Finally,the comparison between the results before and after optimization in ADAMS shows that the ratio of force amplification has increased,and the motion smoothness of moving platen improves well.
2013, 32(9): 1394-1399.
Abstract:
The performance of a clamping system will directly affect the quality of injection-molding products. In the past,the performance of clamping units was optimized by using the single-objective optimization method or traditional multi-objective optimization method,however,the results were not ideal. In this paper,firstly,the mathematical model of the clamping system is established,and a sensitivity analysis method is adopted to determine significant factors from various parameters affecting of the objective functions as design variables,then the NSGAII is applied to optimize the ratio of force amplification and the smoothness of moving-platen speed. Finally,the comparison between the results before and after optimization in ADAMS shows that the ratio of force amplification has increased,and the motion smoothness of moving platen improves well.
The performance of a clamping system will directly affect the quality of injection-molding products. In the past,the performance of clamping units was optimized by using the single-objective optimization method or traditional multi-objective optimization method,however,the results were not ideal. In this paper,firstly,the mathematical model of the clamping system is established,and a sensitivity analysis method is adopted to determine significant factors from various parameters affecting of the objective functions as design variables,then the NSGAII is applied to optimize the ratio of force amplification and the smoothness of moving-platen speed. Finally,the comparison between the results before and after optimization in ADAMS shows that the ratio of force amplification has increased,and the motion smoothness of moving platen improves well.
2013, 32(9): 1400-1404.
Abstract:
In the lack of using LQR( Linear Quadratic Regulator) method to design active suspension controller,a combined genetic algorithm and LQR optimal design method for automotive active suspension controller was studied.To establish the dynamics equations of the vehicle half-car model,LQR controller of active suspension is designed based on stochastic linear optimal control theory,and numerical simulation of the controller is carried out in Matlab/ Simulink environment. According to the simulation results,the performance parameters of controller are optimized using genetic algorithm. Simulation results for controller optimization in time-domain and frequency domain shows that the combined genetic algorithm and LQR optimal design method can quickly obtain the optimal solution;optimized active suspension controller can be used to improve vehicle riding comfort.
In the lack of using LQR( Linear Quadratic Regulator) method to design active suspension controller,a combined genetic algorithm and LQR optimal design method for automotive active suspension controller was studied.To establish the dynamics equations of the vehicle half-car model,LQR controller of active suspension is designed based on stochastic linear optimal control theory,and numerical simulation of the controller is carried out in Matlab/ Simulink environment. According to the simulation results,the performance parameters of controller are optimized using genetic algorithm. Simulation results for controller optimization in time-domain and frequency domain shows that the combined genetic algorithm and LQR optimal design method can quickly obtain the optimal solution;optimized active suspension controller can be used to improve vehicle riding comfort.
