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RSS2012 Vol. 31, No. 1
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2012, 31(1): 1-3.
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Abstract:
In order to investigate the wear mechanism of hydromechanical flow passage components,a rotating experimental device that could simulate actual working conditions of fluid machinery was developed.The device could make an erosion or cavitation wear test and make the interactive erosion and cavitation test.Though adjusting the flux,pressure and injecting angle in the pipeline,the experimental working conditions were controlled.The influences of different parameters(impact angle,specimen material,impact speed,sediment concentration,the particle size,etc.) on the wear of the flow passage components were researched.The micro-morphology of the specimen surface wear scars was analyzed.The wear mechanism of flow passage components of different materials was obtained and the test results had good reproducibility and comparability.
In order to investigate the wear mechanism of hydromechanical flow passage components,a rotating experimental device that could simulate actual working conditions of fluid machinery was developed.The device could make an erosion or cavitation wear test and make the interactive erosion and cavitation test.Though adjusting the flux,pressure and injecting angle in the pipeline,the experimental working conditions were controlled.The influences of different parameters(impact angle,specimen material,impact speed,sediment concentration,the particle size,etc.) on the wear of the flow passage components were researched.The micro-morphology of the specimen surface wear scars was analyzed.The wear mechanism of flow passage components of different materials was obtained and the test results had good reproducibility and comparability.
2012, 31(1): 4-9.
Abstract:
Based on CFD method,the effect of flap parameters on 30P30N three-element airfoils has been studied including the deviation,slot gap and overlap of the flap.The issue focuses on the influence of slot gap and overlap on flow separation and mechanism of the flap.The results indicate that the flow separation of flap reduces lift and diminishes available flap deviation.The slot parameters determine the mixture of the main element boundary layer and slot jet.Meanwhile,those parameters affect the development of the main element boundary layer and the flow separation control of flap at high deviation.The appropriate slot parameters can increase lift by as much as 5%~8%and available flap deviation.However,it makes stall characteristic bad,which should be further studied.Optimizing slot parameters is an effective method to improve available flap deviation of multi-element airfoils.
Based on CFD method,the effect of flap parameters on 30P30N three-element airfoils has been studied including the deviation,slot gap and overlap of the flap.The issue focuses on the influence of slot gap and overlap on flow separation and mechanism of the flap.The results indicate that the flow separation of flap reduces lift and diminishes available flap deviation.The slot parameters determine the mixture of the main element boundary layer and slot jet.Meanwhile,those parameters affect the development of the main element boundary layer and the flow separation control of flap at high deviation.The appropriate slot parameters can increase lift by as much as 5%~8%and available flap deviation.However,it makes stall characteristic bad,which should be further studied.Optimizing slot parameters is an effective method to improve available flap deviation of multi-element airfoils.
2012, 31(1): 10-14.
Abstract:
To apply the rubber pad forming knowledge into digital manufacture of sheet metal parts,the digital manufacturing model for rubber pad forming part is established by using IDEF0.The composition of process knowledge is analyzed and the classification model is put forward,then the approach to building the process knowledge base is proposed.The mode of integrated application of the process knowledge into rubber pad forming is designed,and the web-based process knowledge base and its application system is developed.Finally,the manufacturing model of an aircraft frame and rib part is used to show the knowledge application procedure and verify the effectiveness and practicability of methodology.
To apply the rubber pad forming knowledge into digital manufacture of sheet metal parts,the digital manufacturing model for rubber pad forming part is established by using IDEF0.The composition of process knowledge is analyzed and the classification model is put forward,then the approach to building the process knowledge base is proposed.The mode of integrated application of the process knowledge into rubber pad forming is designed,and the web-based process knowledge base and its application system is developed.Finally,the manufacturing model of an aircraft frame and rib part is used to show the knowledge application procedure and verify the effectiveness and practicability of methodology.
2012, 31(1): 15-18.
Abstract:
In this paper,taking DLR-F4 wing as a base wing,two types of spiroid winglets have been designed to decrease the induced drag.The drag-reduction capability and flow mechanism of spiroid winglets has been simulated by CFD method which is based on N-S equations.The results show that the spiroid winglets have much potential in the aspect of reducing induced drag and enhancing lift.The spiroid winglets can raise the lift coefficient by 12% and the span efficiency factor by 37.5% comparing with the initial geometry without winglets.The spiroid winglets reduce the induced drag by preventing the concentrated wingtip vortex from bringing effectively,it is a promising wingtip drag-reduction technic,which is worthy of further study.
In this paper,taking DLR-F4 wing as a base wing,two types of spiroid winglets have been designed to decrease the induced drag.The drag-reduction capability and flow mechanism of spiroid winglets has been simulated by CFD method which is based on N-S equations.The results show that the spiroid winglets have much potential in the aspect of reducing induced drag and enhancing lift.The spiroid winglets can raise the lift coefficient by 12% and the span efficiency factor by 37.5% comparing with the initial geometry without winglets.The spiroid winglets reduce the induced drag by preventing the concentrated wingtip vortex from bringing effectively,it is a promising wingtip drag-reduction technic,which is worthy of further study.
2012, 31(1): 19-23.
Abstract:
The knowledge-based reasoning of Fabrication Order(FO) approach is proposed in order to design the FO of aircraft sheet metal parts standardly and rapidly.According to the analysis of FO design content,the FO design knowledge classification model of sheet metal parts is proposed.Then the FO reasoning model including Retrieve,Reuse,Revise and Retain is established.Finally the Web-based FO design system is developed.And an example is described to show the reuse and dynamic accumulation of sheet metal parts FO design knowledge is realized effectively.The cycle is shortened and the quality is improved to design order obviously as well.
The knowledge-based reasoning of Fabrication Order(FO) approach is proposed in order to design the FO of aircraft sheet metal parts standardly and rapidly.According to the analysis of FO design content,the FO design knowledge classification model of sheet metal parts is proposed.Then the FO reasoning model including Retrieve,Reuse,Revise and Retain is established.Finally the Web-based FO design system is developed.And an example is described to show the reuse and dynamic accumulation of sheet metal parts FO design knowledge is realized effectively.The cycle is shortened and the quality is improved to design order obviously as well.
2012, 31(1): 24-28.
Abstract:
The trajectory tracking of the end effector of 2-DOF robot in the Cartesian coordinate is implemented by using the resolved acceleration control method.The observer for the unmeasured internal state z is proposed for the friction compensation based on the LuGre friction model.The simulation results indicate that the observer is correct.Through comparisons,the trajectory tracking results obtained by the compensation based on the LuGre friction model agree with the theoretical values better than that based on the Coulomb friction model.
The trajectory tracking of the end effector of 2-DOF robot in the Cartesian coordinate is implemented by using the resolved acceleration control method.The observer for the unmeasured internal state z is proposed for the friction compensation based on the LuGre friction model.The simulation results indicate that the observer is correct.Through comparisons,the trajectory tracking results obtained by the compensation based on the LuGre friction model agree with the theoretical values better than that based on the Coulomb friction model.
2012, 31(1): 29-33.
Abstract:
In order to explore the analysis methods of modular spacecraft,based on the concept of modular design for spacecraft structure,a deployable on-orbit spacecraft modular configuration was established.The influence of simultaneously deployment solar panel and modular structures under the circumstance of weightlessness on the spacecraft's gesture was simulated and analyzed with the assistance of virtual prototype technology.The simulated results show that the deployment of module structures is vital to the angle and velocity of spacecraft's gesture.Within the Eclipse environment,a structural design and analysis platform for spacecraft was developed with J2EE.The structure design,assembly and dynamics analysis of spacecraft were well integrated,and the rapid response of structural design and digital prototype assembly to dynamics analysis of spacecraft was consequently achieved in this simulation platform.
In order to explore the analysis methods of modular spacecraft,based on the concept of modular design for spacecraft structure,a deployable on-orbit spacecraft modular configuration was established.The influence of simultaneously deployment solar panel and modular structures under the circumstance of weightlessness on the spacecraft's gesture was simulated and analyzed with the assistance of virtual prototype technology.The simulated results show that the deployment of module structures is vital to the angle and velocity of spacecraft's gesture.Within the Eclipse environment,a structural design and analysis platform for spacecraft was developed with J2EE.The structure design,assembly and dynamics analysis of spacecraft were well integrated,and the rapid response of structural design and digital prototype assembly to dynamics analysis of spacecraft was consequently achieved in this simulation platform.
2012, 31(1): 34-37.
Abstract:
We propose a new micro-displacement amplifer that uses the GMM(giant magnetostrictive material) driver of a high-speed on/off valve.This amplifer uses the "nested" and "tandem-arrayed" structure with GMM rods.According to the performances of the GMM rods,we manufacture a prototype of "nested" amplifier to be used for the GMM driver.We test the displacement of the GMM driver under different loads.The test results show that the prototype GMM driver which uses a coil with 1 700 turns and φ0.7 mm wires has the response time of less than 1.5 ms,the maximum load of 700 N and the displacement output of 78 μm under the load of 150 N,indicating that the GMM driver can well meet the requirements for driving a high-speed on/off valve.
We propose a new micro-displacement amplifer that uses the GMM(giant magnetostrictive material) driver of a high-speed on/off valve.This amplifer uses the "nested" and "tandem-arrayed" structure with GMM rods.According to the performances of the GMM rods,we manufacture a prototype of "nested" amplifier to be used for the GMM driver.We test the displacement of the GMM driver under different loads.The test results show that the prototype GMM driver which uses a coil with 1 700 turns and φ0.7 mm wires has the response time of less than 1.5 ms,the maximum load of 700 N and the displacement output of 78 μm under the load of 150 N,indicating that the GMM driver can well meet the requirements for driving a high-speed on/off valve.
2012, 31(1): 38-43.
Abstract:
Uniform metal Droplet Spray Manufacturing is a rapid prototyping technique,which deposits uniform metal droplet to building mininiaturized object by point to point,it can be divided into continuous uniform metal droplet spray technology and on-demand uniform metal droplet spray technology.Without the requirements on preformed mandrels or expensive equipments in the manufacturing process,the promising technique has many advantages and broad application prospects,such as low cost,high efficiency and low energy consuming.The principle of those technique,related features,applications and research development in micro-manufacturing were introduced in this paper.The working principles of the two uniform metal droplet spray forming were explained.Those technologies were droven by the piezoelectric actuator and gas pressure actuator,respectively.The key technologies in metal with low melting point spray and high melting point spray were proposed.At last,the future trend of those technologies development and application in direct metal rapid prototyping of metal structural components,electronic packaging,uniform metal coatings and printing of electrocircuit were discussed.
Uniform metal Droplet Spray Manufacturing is a rapid prototyping technique,which deposits uniform metal droplet to building mininiaturized object by point to point,it can be divided into continuous uniform metal droplet spray technology and on-demand uniform metal droplet spray technology.Without the requirements on preformed mandrels or expensive equipments in the manufacturing process,the promising technique has many advantages and broad application prospects,such as low cost,high efficiency and low energy consuming.The principle of those technique,related features,applications and research development in micro-manufacturing were introduced in this paper.The working principles of the two uniform metal droplet spray forming were explained.Those technologies were droven by the piezoelectric actuator and gas pressure actuator,respectively.The key technologies in metal with low melting point spray and high melting point spray were proposed.At last,the future trend of those technologies development and application in direct metal rapid prototyping of metal structural components,electronic packaging,uniform metal coatings and printing of electrocircuit were discussed.
2012, 31(1): 44-48.
Abstract:
A rack cutter with curvilinear shaped is considered,with which the equations of tooth surface of face gear are deduced by generated method.Based on tooth contact analysis of face gear drive with curved-tooth pinion,loaded tooth contact analysis with finite-element method and mathematical programming is represented.The simulation results show that the magnitude of load on the flank of tooth is even distributed,the magnitude of loaded transmission errors is less than 5 arcsec and the tension stress introduced by loading is small with a torque of 550 N穖.
A rack cutter with curvilinear shaped is considered,with which the equations of tooth surface of face gear are deduced by generated method.Based on tooth contact analysis of face gear drive with curved-tooth pinion,loaded tooth contact analysis with finite-element method and mathematical programming is represented.The simulation results show that the magnitude of load on the flank of tooth is even distributed,the magnitude of loaded transmission errors is less than 5 arcsec and the tension stress introduced by loading is small with a torque of 550 N穖.
2012, 31(1): 49-52.
Abstract:
Through using the tapered roller-bearing axial fault vibration signal,we get the response characteristics and take advantage of BP neural network for fault diagnosis.Firstly,a new wavelet-denoising algorithm is used to pre-monitor signals,which is based on the best selection of orthogonal wavelet bases,aiming at the minimum entropy effect in the process of Wavelet Shrinkage.Then use the fuzzy information granulation to granulate the noised signal;followed signal of fuzzy granular layer wavelet packet decomposition and reconstruction,by no fault and fault feature vectors.Finally,take the feature vectors as input and use BP neural network for fault diagnosis.Fault signal is verified by experiments and the signal after denoising is better for feature extraction;meanwhile,the signal after fuzzy granulation can be used for more accurate fault diagnosis.
Through using the tapered roller-bearing axial fault vibration signal,we get the response characteristics and take advantage of BP neural network for fault diagnosis.Firstly,a new wavelet-denoising algorithm is used to pre-monitor signals,which is based on the best selection of orthogonal wavelet bases,aiming at the minimum entropy effect in the process of Wavelet Shrinkage.Then use the fuzzy information granulation to granulate the noised signal;followed signal of fuzzy granular layer wavelet packet decomposition and reconstruction,by no fault and fault feature vectors.Finally,take the feature vectors as input and use BP neural network for fault diagnosis.Fault signal is verified by experiments and the signal after denoising is better for feature extraction;meanwhile,the signal after fuzzy granulation can be used for more accurate fault diagnosis.
2012, 31(1): 53-58.
Abstract:
We perform the wavelet decomposition of the fault signal of a rolling bearing to obtain its resonance frequency band and then demodulate its envelop with the wavelet transform.Then we carry out the blind source separation of the fault signal thus demodulated and the frequency spectral transform of the fault signal thus separated.The frequency spectral diagram clearly shows the frequencies of the fault features of the rolling bearing.Finally,we use the experimental rig for the fault diagnosis of a rotor-rolling bearing to simulate its coupling fault.The simulation examples verify that our fault diagnosis method has better de-noising capability and can better extract the fault features of the rolling bearing.
We perform the wavelet decomposition of the fault signal of a rolling bearing to obtain its resonance frequency band and then demodulate its envelop with the wavelet transform.Then we carry out the blind source separation of the fault signal thus demodulated and the frequency spectral transform of the fault signal thus separated.The frequency spectral diagram clearly shows the frequencies of the fault features of the rolling bearing.Finally,we use the experimental rig for the fault diagnosis of a rotor-rolling bearing to simulate its coupling fault.The simulation examples verify that our fault diagnosis method has better de-noising capability and can better extract the fault features of the rolling bearing.
2012, 31(1): 59-62.
Abstract:
We establish the FE model of the crack-arresting stringer of the integrated wing beam structure with the finite element software ABAQUS and calculate its stress intensity factors and T-stress.We predict the crack turning angle of the crack-arresting stringer with the first-order maximum tangential stress theory and the second-order maximum tangential stress theory and then compare the prediction results with the experimental results.The comparison results show that the second-order maximum tangential stress theory can predict the sharp turning at the tip of the crack near the crack-arresting stringer more accurately than the first-order one.Then we discuss the effects of the various thicknesses of the wing beam structure on the crack turning.The discussion results show that the crack turning angle increases with increasing stiffness ratio of the crack-suppressing stringer,thus being more effective for arresting the cracks of the integrated wing beam structure.
We establish the FE model of the crack-arresting stringer of the integrated wing beam structure with the finite element software ABAQUS and calculate its stress intensity factors and T-stress.We predict the crack turning angle of the crack-arresting stringer with the first-order maximum tangential stress theory and the second-order maximum tangential stress theory and then compare the prediction results with the experimental results.The comparison results show that the second-order maximum tangential stress theory can predict the sharp turning at the tip of the crack near the crack-arresting stringer more accurately than the first-order one.Then we discuss the effects of the various thicknesses of the wing beam structure on the crack turning.The discussion results show that the crack turning angle increases with increasing stiffness ratio of the crack-suppressing stringer,thus being more effective for arresting the cracks of the integrated wing beam structure.
2012, 31(1): 63-66.
Abstract:
A burner is important for producing cement.Its performance has great impact on the cost and quality of the cement it produces.This paper uses the softwares of UG and Fluent to establish the 3-dimensional model of the 4-channel coal burner and generate its structural mesh.It also uses the realizable κ-ε turbulence model and the simple algorithm to study and simulate the changes in the inner flow field of the 4-channel coal burner,thus obtaining the contours of the flow field which agree with the actual conditions.The realizable κ-ε model is feasible and the simulation results are reliable.This study sheds some light on improving the structure of a 4-channel coal burner and optimizing its parameters.
A burner is important for producing cement.Its performance has great impact on the cost and quality of the cement it produces.This paper uses the softwares of UG and Fluent to establish the 3-dimensional model of the 4-channel coal burner and generate its structural mesh.It also uses the realizable κ-ε turbulence model and the simple algorithm to study and simulate the changes in the inner flow field of the 4-channel coal burner,thus obtaining the contours of the flow field which agree with the actual conditions.The realizable κ-ε model is feasible and the simulation results are reliable.This study sheds some light on improving the structure of a 4-channel coal burner and optimizing its parameters.
2012, 31(1): 67-70.
Abstract:
For a straight tube Coriolis mass flowmeter,the slight curve of measure tube as the high pressure fluid flows will cause a measurement error.Beginning from the tube stiffness model,the flow calibrate coefficient of the slight curve tube is calculated with the curve beam formula based on the situation that load is vertical to the curvature,then compared with the flow calibrate coefficient of the straight tube as there is no pressure.It is concluded that the measured value is greater than the practical value when the high pressure fluid flows.The conclusion is consistent with industry field result and the datasheet of the E+H.
For a straight tube Coriolis mass flowmeter,the slight curve of measure tube as the high pressure fluid flows will cause a measurement error.Beginning from the tube stiffness model,the flow calibrate coefficient of the slight curve tube is calculated with the curve beam formula based on the situation that load is vertical to the curvature,then compared with the flow calibrate coefficient of the straight tube as there is no pressure.It is concluded that the measured value is greater than the practical value when the high pressure fluid flows.The conclusion is consistent with industry field result and the datasheet of the E+H.
2012, 31(1): 71-74.
Abstract:
Using a rotor's rotational speed and vibration signal,we apply a method for continuous gain scheduling proportional integral(GSPI) control to perform the on-line control of the large sudden unbalanced vibration response of a rotor with an active elastic support/dry friction damper,with the parameters of the rotor being unknown to us or inaccurate.The experimental results show that the GSPI control method that uses the active elastic support/dry friction damper can effectively control the sudden unbalanced vibration response.
Using a rotor's rotational speed and vibration signal,we apply a method for continuous gain scheduling proportional integral(GSPI) control to perform the on-line control of the large sudden unbalanced vibration response of a rotor with an active elastic support/dry friction damper,with the parameters of the rotor being unknown to us or inaccurate.The experimental results show that the GSPI control method that uses the active elastic support/dry friction damper can effectively control the sudden unbalanced vibration response.
2012, 31(1): 75-78.
Abstract:
According to low-performance operation of large and pure lag system of cone crusher control system,a new artificial control method based on brain emotional learning(BEL) model is proposed in this paper,which has great learning capability and can compute simply.BEL model is the computing model of delivery method between Amygdale of brain and Orbitofrontal organizational information,called A-O system model.The learning is mainly taking place in the Amygdale,and Orbitofrontal is assisting amygdale for learning.BEL model will reach the optimum control effect through constantly adjusting its node weights.The BEL intelligent controller is used to control cone crusher system and the simulation results show that the BEL controller has fast response speed and strong robustness.
According to low-performance operation of large and pure lag system of cone crusher control system,a new artificial control method based on brain emotional learning(BEL) model is proposed in this paper,which has great learning capability and can compute simply.BEL model is the computing model of delivery method between Amygdale of brain and Orbitofrontal organizational information,called A-O system model.The learning is mainly taking place in the Amygdale,and Orbitofrontal is assisting amygdale for learning.BEL model will reach the optimum control effect through constantly adjusting its node weights.The BEL intelligent controller is used to control cone crusher system and the simulation results show that the BEL controller has fast response speed and strong robustness.
2012, 31(1): 79-82.
Abstract:
An optimization strategy based on quadratic response surface model is proposed in this paper,combining the exact analysis of aerodynamic performances and concept analysis of structural weight.With the integration of adaptive simulated annealing algorithm and sequential quadratic programming method,the multi-disciplinary design optimization of a high-speed transport wing is processed to search for a compromised point of the best aerodynamic layout and the minimum take-off gross weight.Aerodynamic and structural performances are preliminarily analyzed and effectively improved.
An optimization strategy based on quadratic response surface model is proposed in this paper,combining the exact analysis of aerodynamic performances and concept analysis of structural weight.With the integration of adaptive simulated annealing algorithm and sequential quadratic programming method,the multi-disciplinary design optimization of a high-speed transport wing is processed to search for a compromised point of the best aerodynamic layout and the minimum take-off gross weight.Aerodynamic and structural performances are preliminarily analyzed and effectively improved.
2012, 31(1): 83-86.
Abstract:
Based on the tilt generated cutting principle,a numerical algorithm of scallop height was proposed to control the cutting surface quality of spiral bevel gears.The cutting process was described as a series of non-continuous cutting movements of blades.The design parameters of cutter blades and cutting process parameters were combined to build the mathematical tooth surface model.The mathematical model established the relationship among the scallop height,the blades number,the cutter rotational speed,the roll rate and the roll rotation angle.According to the mathematical model,scallop heights were computed by numerical algorithm and the influence of cutting process parameters was analysed.A practical example was provided to calculate scallop heights on the different areas of the tooth surface.The tooth surface roughness was evaluated to offer reference for practice.The scallop height calculation results were consistent with simulation measurements to prove the accuracy of the algorithm.
Based on the tilt generated cutting principle,a numerical algorithm of scallop height was proposed to control the cutting surface quality of spiral bevel gears.The cutting process was described as a series of non-continuous cutting movements of blades.The design parameters of cutter blades and cutting process parameters were combined to build the mathematical tooth surface model.The mathematical model established the relationship among the scallop height,the blades number,the cutter rotational speed,the roll rate and the roll rotation angle.According to the mathematical model,scallop heights were computed by numerical algorithm and the influence of cutting process parameters was analysed.A practical example was provided to calculate scallop heights on the different areas of the tooth surface.The tooth surface roughness was evaluated to offer reference for practice.The scallop height calculation results were consistent with simulation measurements to prove the accuracy of the algorithm.
2012, 31(1): 87-95.
Abstract:
To study design process optimization and reuse,an approach to model design process gene is presented with extensible basic-element.Firstly,the principle of gene engineering-based design process optimization and reuse is put forward and analyzed;Secondly,by analyzing the concept and structure of design process gene,as well as the concept of extensible basic-element and its extensibility,the extensible basic-element model of design process gene is established following the extensible basic-element models of design process bases and pairs of design process bases.Then the properties of radiation and expandability out of all the extensibilities of the design process gene model are analyzed and mutation of design process gene is performed by extensible transformations.Finally,the examples of modelling basic-element models of design process gene,bases and pairs of bases extracted from a mechanical design process and the design process gene mutation in airplane design process are given to illustrate the approach.
To study design process optimization and reuse,an approach to model design process gene is presented with extensible basic-element.Firstly,the principle of gene engineering-based design process optimization and reuse is put forward and analyzed;Secondly,by analyzing the concept and structure of design process gene,as well as the concept of extensible basic-element and its extensibility,the extensible basic-element model of design process gene is established following the extensible basic-element models of design process bases and pairs of design process bases.Then the properties of radiation and expandability out of all the extensibilities of the design process gene model are analyzed and mutation of design process gene is performed by extensible transformations.Finally,the examples of modelling basic-element models of design process gene,bases and pairs of bases extracted from a mechanical design process and the design process gene mutation in airplane design process are given to illustrate the approach.
2012, 31(1): 96-100.
Abstract:
The structural model of a detachable grip is designed by using drawing software Pro/E.The structure is further simplified and optimized for reducing mass and saving computation time.After modal analysis of the grip is finished by using finite element software ANSYS,its natural frequencies and low modes of vibrations are extracted and compared with those of original structure for verifying the modeling and optimization.The suggestion of the frequencies for the grip's safe operation is given.The modal analysis result for the underneath aerial ropeway detachable grip is a good preparation for further dynamic analysis.
The structural model of a detachable grip is designed by using drawing software Pro/E.The structure is further simplified and optimized for reducing mass and saving computation time.After modal analysis of the grip is finished by using finite element software ANSYS,its natural frequencies and low modes of vibrations are extracted and compared with those of original structure for verifying the modeling and optimization.The suggestion of the frequencies for the grip's safe operation is given.The modal analysis result for the underneath aerial ropeway detachable grip is a good preparation for further dynamic analysis.
2012, 31(1): 101-106.
Abstract:
An internal model and an inverse model of nonlinear system are established based on Weighted Least Squares Support Vector Machines(Weighted LS-SVM).Then the algorithm of internal model control for nonlinear system based on Weighted LS-SVM is proposed.The simulation results show that the internal model and the inverse model of nonlinear system based on Weighted LS-SVM have high modeling precision and strong generalization ability.And the algorithm of internal model control for nonlinear system based on Weighted LS-SVM has good control performance,strong anti-jamming ability and robustness.
An internal model and an inverse model of nonlinear system are established based on Weighted Least Squares Support Vector Machines(Weighted LS-SVM).Then the algorithm of internal model control for nonlinear system based on Weighted LS-SVM is proposed.The simulation results show that the internal model and the inverse model of nonlinear system based on Weighted LS-SVM have high modeling precision and strong generalization ability.And the algorithm of internal model control for nonlinear system based on Weighted LS-SVM has good control performance,strong anti-jamming ability and robustness.
2012, 31(1): 107-112.
Abstract:
In order to control a wheeled mobile robot whose mass center does not coincide with its geometrical center,we propose an adaptive sliding-mode trajectory tracking control law that has global asymptotical stability.We design a kinematic controller according to the kinematic model of the wheeled mobile robot.Using the kinematic model and the kinematic controller,we design an adaptive sliding-mode controller with the backstepping technique and the integral sliding-mode control algorithm,which can overcome unknown disturbances effectively.We use the Lyapunov stability theory to prove the stability of the wheeled mobile robot and its tracking error convergence.Our control law satisfies the trajectory tracking requirements for the wheeled mobile robot and has good robustness.Finally,we use two simulation examples to demonstrate the effectiveness and correctness of our control law.
In order to control a wheeled mobile robot whose mass center does not coincide with its geometrical center,we propose an adaptive sliding-mode trajectory tracking control law that has global asymptotical stability.We design a kinematic controller according to the kinematic model of the wheeled mobile robot.Using the kinematic model and the kinematic controller,we design an adaptive sliding-mode controller with the backstepping technique and the integral sliding-mode control algorithm,which can overcome unknown disturbances effectively.We use the Lyapunov stability theory to prove the stability of the wheeled mobile robot and its tracking error convergence.Our control law satisfies the trajectory tracking requirements for the wheeled mobile robot and has good robustness.Finally,we use two simulation examples to demonstrate the effectiveness and correctness of our control law.
2012, 31(1): 113-117.
Abstract:
In this paper,a detection acquisition system for vibration signals of probability sieve was set up by means of LabView.An autoregressive(AR) model of vibration signal was established accordingly.Through the feature analysis of AR bispectrum and its diagonal slices of different screen efficiency prediction signal and examination of the law of screen efficiency prediction,the results show that the method is feasible.
In this paper,a detection acquisition system for vibration signals of probability sieve was set up by means of LabView.An autoregressive(AR) model of vibration signal was established accordingly.Through the feature analysis of AR bispectrum and its diagonal slices of different screen efficiency prediction signal and examination of the law of screen efficiency prediction,the results show that the method is feasible.
2012, 31(1): 118-121.
Abstract:
Regarding the large mass of some type of Gantry Milling machine column,this paper adopts Parametric Design Language APDL to set up finite element model and make statics analysis according to the limit working conditions of the Gantry Milling machine column.Based on the statics analysis,the topology optimization method of column structure is proposed,and the optimal design method is established to minimize the weight.The finite element analysis is made again to analyze the optimized column structure for verification.The result of analysis indicates that compared with the traditional design made through experience,weight of column designed by topology optimization method can reduce 10%.Moreover,the critical displacement and maximum stress are not affected for achieving the design of light column.
Regarding the large mass of some type of Gantry Milling machine column,this paper adopts Parametric Design Language APDL to set up finite element model and make statics analysis according to the limit working conditions of the Gantry Milling machine column.Based on the statics analysis,the topology optimization method of column structure is proposed,and the optimal design method is established to minimize the weight.The finite element analysis is made again to analyze the optimized column structure for verification.The result of analysis indicates that compared with the traditional design made through experience,weight of column designed by topology optimization method can reduce 10%.Moreover,the critical displacement and maximum stress are not affected for achieving the design of light column.
2012, 31(1): 122-124.
Abstract:
At present,the large number of accuracy evaluation for CNC machine tool lead to the operator's misunderstanding of the standards.Therefore,in this paper the two evaluation standards for two kinds of common evaluation methods for detecting and evaluating CNC positioning accuracy and repositioning accuracy with direct separate measurement of machine axes are introduced.By the analysis and comparison of those methods,it also clarifies the various concrete situations when the two methods are applied to guarantee the processing accuracy of the products.
At present,the large number of accuracy evaluation for CNC machine tool lead to the operator's misunderstanding of the standards.Therefore,in this paper the two evaluation standards for two kinds of common evaluation methods for detecting and evaluating CNC positioning accuracy and repositioning accuracy with direct separate measurement of machine axes are introduced.By the analysis and comparison of those methods,it also clarifies the various concrete situations when the two methods are applied to guarantee the processing accuracy of the products.
2012, 31(1): 125-129.
Abstract:
It is difficult to cut median-hardness helical gears on ordinary gear hobber with the ordinary high speed steel hob,the ordinary high speed steel hob and coated hob are chosen to manufacture 42CrMo gear shaft with HB290~330 and HRC48~53 on YN31125 gear hobber.The results indicate that the processing parameters and material hobs is chosen for different material gear shaft,especially in order to play the coated hob's high hardness and good wear resistance advantage,the hobbing process is analyzed and optimized with the improvement,the coated hob shows the 3~ 5 times of lifetime and 50% increasing in cutting speed.The results also get the relationship between the coated material of the hob and the hardness.
It is difficult to cut median-hardness helical gears on ordinary gear hobber with the ordinary high speed steel hob,the ordinary high speed steel hob and coated hob are chosen to manufacture 42CrMo gear shaft with HB290~330 and HRC48~53 on YN31125 gear hobber.The results indicate that the processing parameters and material hobs is chosen for different material gear shaft,especially in order to play the coated hob's high hardness and good wear resistance advantage,the hobbing process is analyzed and optimized with the improvement,the coated hob shows the 3~ 5 times of lifetime and 50% increasing in cutting speed.The results also get the relationship between the coated material of the hob and the hardness.
2012, 31(1): 130-134.
Abstract:
Three kinds landing gear actuating cylinder's inner-locks of aircraft: block ring lock,ball lock,finger lock are taken as study object base on some aircraft typical inner-lock practical application,the working principle of the three typical actuating cylinder's inner-locks are described,the stress and workmanship requirements of the three inner-lock key components are analysised.It is found that the ball lock requires small locking pressure and it is easy to be fabricated and installed,the block ring lock requires large locking pressure and high workmanship requirements,while finger lock also requires large lock pressure with stable working behaviour but is difficult to be fabricated and installed.
Three kinds landing gear actuating cylinder's inner-locks of aircraft: block ring lock,ball lock,finger lock are taken as study object base on some aircraft typical inner-lock practical application,the working principle of the three typical actuating cylinder's inner-locks are described,the stress and workmanship requirements of the three inner-lock key components are analysised.It is found that the ball lock requires small locking pressure and it is easy to be fabricated and installed,the block ring lock requires large locking pressure and high workmanship requirements,while finger lock also requires large lock pressure with stable working behaviour but is difficult to be fabricated and installed.
2012, 31(1): 135-137.
Abstract:
An overhead traveling crane's vibration causes resonance and fatigue damage,thus affecting the life of machinery equipment.This paper finds out the causes of the vibration and conducts the finite element(FE) modal analysis of the double-girder structure of the overhead traveling crane,obtaining the inherent frequencies and vibration modes of the girder under the modals of various orders.With the parameters obtained through the FE modal analysis,the paper modifies the FE model of the girder so that its inherent frequencies can be far away from the frequency of externally-excited vibration,thus avoiding the resonance.It provides a theoretical basis for the girder's dynamics modification.
An overhead traveling crane's vibration causes resonance and fatigue damage,thus affecting the life of machinery equipment.This paper finds out the causes of the vibration and conducts the finite element(FE) modal analysis of the double-girder structure of the overhead traveling crane,obtaining the inherent frequencies and vibration modes of the girder under the modals of various orders.With the parameters obtained through the FE modal analysis,the paper modifies the FE model of the girder so that its inherent frequencies can be far away from the frequency of externally-excited vibration,thus avoiding the resonance.It provides a theoretical basis for the girder's dynamics modification.
2012, 31(1): 138-140,145.
Abstract:
Bolt connection is an important mechanical connection method.The fatigue strength of the structure could affect the servceing life of product.The new fit method is developed in order to improve the fatigue strength of the structure.In this paper,the enhancement of interference-fit and the characteristic of interference-fit fastener manufactured by titanium alloy using stress wave are introduced.The fatigue life of the sample is determined by using fatigue experiment and the microstructure is observed by using metallgraphray analysis.Those aspects have been compared between the traditional and the stress wave method.The present results indicate that the stress wave method can form a better residual compressive stress area and provide a high fatigue life.
Bolt connection is an important mechanical connection method.The fatigue strength of the structure could affect the servceing life of product.The new fit method is developed in order to improve the fatigue strength of the structure.In this paper,the enhancement of interference-fit and the characteristic of interference-fit fastener manufactured by titanium alloy using stress wave are introduced.The fatigue life of the sample is determined by using fatigue experiment and the microstructure is observed by using metallgraphray analysis.Those aspects have been compared between the traditional and the stress wave method.The present results indicate that the stress wave method can form a better residual compressive stress area and provide a high fatigue life.
2012, 31(1): 141-145.
Abstract:
To optimize the design of equipment and lay the foundation for atomizing the gas-liquid water jet of pulsed anti-riots water cannon,we did the experimental study of it and then use four kinds of simulation scheme to simulate the experimental conditions,thus obtaining the large eddy simulation method coupled with the 2-D unsteady implicit VOF model,which can give a better description of the high-speed gas-liquid water jet.The simulation results agree well with the experimental results.We also perform the simulation of changing numerical parameters and structural parameters;the simulation results show that: 1) the initial pressure and initial water weight of the gas-liquid water jet exert obvious influences on the performance of the water cannon;2) the shorter the pipe of the water cannon,the more fully the water jet is atomized;the longer the pipe,the more effectively the water cannon jets.
To optimize the design of equipment and lay the foundation for atomizing the gas-liquid water jet of pulsed anti-riots water cannon,we did the experimental study of it and then use four kinds of simulation scheme to simulate the experimental conditions,thus obtaining the large eddy simulation method coupled with the 2-D unsteady implicit VOF model,which can give a better description of the high-speed gas-liquid water jet.The simulation results agree well with the experimental results.We also perform the simulation of changing numerical parameters and structural parameters;the simulation results show that: 1) the initial pressure and initial water weight of the gas-liquid water jet exert obvious influences on the performance of the water cannon;2) the shorter the pipe of the water cannon,the more fully the water jet is atomized;the longer the pipe,the more effectively the water cannon jets.
2012, 31(1): 146-149,153.
Abstract:
In this study a DOE(Design of Experiment)-based structural optimization method is developed to reduce the radiated noise of range hoods.First,a finite element model of a typical range hood is created using Hypermesh.Then,the surface particle velocity is carried out in Nastran,and the radiated noise is calculated by Sysnoise.Finally,the DOE-based structural optimization is preformed using iSIGHT-FD,in which the sound pressure level at four sensitive points and the radiated sound power are selected as the objective function and the thickness of four panels are adopted as design variables.In addition,the weight of the range hood as a constraint is kept no more than its original weight.As a result,a maximum radiated sound power reduction of 3.66 W and a maximum sound pressure level reduction of 4.7 dB are successfully achieved.
In this study a DOE(Design of Experiment)-based structural optimization method is developed to reduce the radiated noise of range hoods.First,a finite element model of a typical range hood is created using Hypermesh.Then,the surface particle velocity is carried out in Nastran,and the radiated noise is calculated by Sysnoise.Finally,the DOE-based structural optimization is preformed using iSIGHT-FD,in which the sound pressure level at four sensitive points and the radiated sound power are selected as the objective function and the thickness of four panels are adopted as design variables.In addition,the weight of the range hood as a constraint is kept no more than its original weight.As a result,a maximum radiated sound power reduction of 3.66 W and a maximum sound pressure level reduction of 4.7 dB are successfully achieved.
2012, 31(1): 150-153.
Abstract:
The large integral panel is the main structure part of modern advanced civil airplane.The large integral panel forming is an important key technology which must be solved in the airplane developing processes.The ageing forming is an effective method for forming large skin and wall pieces.The principle and characteristics of the ageing forming are analyzed.The processing scheme of the ageing forming for the high-rib complex shaped of panel is discussed and analyzed.Finally,based on the existing research situation and the requirements for developing the large airplane in China,the experimental suggestion and research emphasis on developing ageing forming are pointed out.
The large integral panel is the main structure part of modern advanced civil airplane.The large integral panel forming is an important key technology which must be solved in the airplane developing processes.The ageing forming is an effective method for forming large skin and wall pieces.The principle and characteristics of the ageing forming are analyzed.The processing scheme of the ageing forming for the high-rib complex shaped of panel is discussed and analyzed.Finally,based on the existing research situation and the requirements for developing the large airplane in China,the experimental suggestion and research emphasis on developing ageing forming are pointed out.
2012, 31(1): 154-158,162.
Abstract:
The 5-axis machining postprocessor of non-orthogonal machine tool is difficult to develop.After analyzing structural characteristics of DMG non-orthogonal Table-Table machining center,control system of HEIDENHAIN iTNC530 and 5-axis fixed-position milling programming,a postprocessing algorithm of 5-axis fixed-position milling is presented in this paper.Based on the algorithm,the relative postprocessor is developed by Visual C++ 6.0 to convert tool path file to G-code file of HEIDENHAIN format.A simulation model of the machine is established by Vericut 7.0 to simulate G-code files created by the program.The simulation result justifies the postprocessing algorithm proposed.
The 5-axis machining postprocessor of non-orthogonal machine tool is difficult to develop.After analyzing structural characteristics of DMG non-orthogonal Table-Table machining center,control system of HEIDENHAIN iTNC530 and 5-axis fixed-position milling programming,a postprocessing algorithm of 5-axis fixed-position milling is presented in this paper.Based on the algorithm,the relative postprocessor is developed by Visual C++ 6.0 to convert tool path file to G-code file of HEIDENHAIN format.A simulation model of the machine is established by Vericut 7.0 to simulate G-code files created by the program.The simulation result justifies the postprocessing algorithm proposed.
2012, 31(1): 159-162.
Abstract:
Polytetrafluoroethene(PTFE) has very low friction coefficient.We use bismaleimide(BMI) modified with fluorinated carbon nanotubes(F-CNTs) as resin matrix to prepare PTFE/F-CNTs/BMI composites so as to obtain a high-performance anti-wear composite material.We study the effect of PTFE on the mechanical and tribological properties of PTFE/F-CNTs/BMI composites.The study results show that the PTFE of an appropriate content can enhance the toughness of the modified resin matrix.When the content of PTFE is 2.0ωt%,its impact is the best.The impact of nanocomposites is 7.39 kJ/m2,an increase of 54.07% compared with F-CNTs/BMI composite.PTFE can decrease the friction coefficient of F-CNTs/BMI composite but has little effect to its wear rate.The friction coefficient of the F-CNTs/BMI composite with 2.0ωt% PTFE decreases remarkably from 0.38 to 0.29.
Polytetrafluoroethene(PTFE) has very low friction coefficient.We use bismaleimide(BMI) modified with fluorinated carbon nanotubes(F-CNTs) as resin matrix to prepare PTFE/F-CNTs/BMI composites so as to obtain a high-performance anti-wear composite material.We study the effect of PTFE on the mechanical and tribological properties of PTFE/F-CNTs/BMI composites.The study results show that the PTFE of an appropriate content can enhance the toughness of the modified resin matrix.When the content of PTFE is 2.0ωt%,its impact is the best.The impact of nanocomposites is 7.39 kJ/m2,an increase of 54.07% compared with F-CNTs/BMI composite.PTFE can decrease the friction coefficient of F-CNTs/BMI composite but has little effect to its wear rate.The friction coefficient of the F-CNTs/BMI composite with 2.0ωt% PTFE decreases remarkably from 0.38 to 0.29.
2012, 31(1): 163-166,172.
Abstract:
LNG submerged pump was designed for LNG car gas station.The composition,capability requirement and key technology of LNG submerged pump were introduced.Insulation processing and nitrogen seal protection system assured motor seal shield and explosion-proof.Thrust equalizing mechanism(TEM) and diffuser vane were used to solve balance of axial and the radial forces when LNG submerged pump was running.The cavitation erosion was improved by using spiral flow diverter and the thermal stress was resolved through bracket structure.Through the experimental tests and on-the-spot operating,this LNG submerged pump performs well in these cases,such as unloading,precooling and the air entrainment,which satisfies all design requirements.
LNG submerged pump was designed for LNG car gas station.The composition,capability requirement and key technology of LNG submerged pump were introduced.Insulation processing and nitrogen seal protection system assured motor seal shield and explosion-proof.Thrust equalizing mechanism(TEM) and diffuser vane were used to solve balance of axial and the radial forces when LNG submerged pump was running.The cavitation erosion was improved by using spiral flow diverter and the thermal stress was resolved through bracket structure.Through the experimental tests and on-the-spot operating,this LNG submerged pump performs well in these cases,such as unloading,precooling and the air entrainment,which satisfies all design requirements.
2012, 31(1): 167-172.
Abstract:
By analyzing sound signal,this paper analysis the sound signal of a kind of compact horizontal driver in advanced automobile seats to evaluate the sound quality.The sym6 wavelet was employed to de-noise given sound signal,and a band-pass filter was used to acquire specific frequency band of the de-noised signal.Hilbert transform was then adopted to demodulate filtered signal the main component of the demodulated signal was the characteristic signal containing fault information of the driver;consequently,a low-pass filter was utilized to eliminate high frequency noise and the anticipated signal containing fault information thus was acquired;fourier transform was performed for the low-pass filtered signal to obtain its frequency spectrum.Finally,the amplitude of the signal at characteristic frequency was compared with a preset threshold to determine if the driver was defective or of poor sound quality.This method had high detection accuracy and anti-noise ability over the whole frequency band.
By analyzing sound signal,this paper analysis the sound signal of a kind of compact horizontal driver in advanced automobile seats to evaluate the sound quality.The sym6 wavelet was employed to de-noise given sound signal,and a band-pass filter was used to acquire specific frequency band of the de-noised signal.Hilbert transform was then adopted to demodulate filtered signal the main component of the demodulated signal was the characteristic signal containing fault information of the driver;consequently,a low-pass filter was utilized to eliminate high frequency noise and the anticipated signal containing fault information thus was acquired;fourier transform was performed for the low-pass filtered signal to obtain its frequency spectrum.Finally,the amplitude of the signal at characteristic frequency was compared with a preset threshold to determine if the driver was defective or of poor sound quality.This method had high detection accuracy and anti-noise ability over the whole frequency band.
