Author Center
Editor Work
Peer Review
Editorial Entry
Email Alert
RSS2013 Vol. 32, No. 1
Display Method:
2013, 32(1): 1-5.
PDF 958KB
Abstract:
For the under-actuated linkage mechanism,techniques to control and anti-control chaos are the crucialproblem for the prevention or utilization of chaos. In this paper,by adding a linear spring to an under-actuated pla-nar five-bar mechanism,the force applied to the mechanism was changed,therefore,the control and anti-control ofchaotic motion of the mechanism was implemented. In the bifurcation diagram with the location of spring as the pa-rameter,it is indicated that the different locations of the spring lead to different motions of the mechanism,such aschaotic and periodic motions. A helical pair was used to adjust the location of the spring. In this way,a simple butefficient technique to control and anti-control chaos was created,which was proved by the phase diagram and thelargest Lyapunov exponent.
For the under-actuated linkage mechanism,techniques to control and anti-control chaos are the crucialproblem for the prevention or utilization of chaos. In this paper,by adding a linear spring to an under-actuated pla-nar five-bar mechanism,the force applied to the mechanism was changed,therefore,the control and anti-control ofchaotic motion of the mechanism was implemented. In the bifurcation diagram with the location of spring as the pa-rameter,it is indicated that the different locations of the spring lead to different motions of the mechanism,such aschaotic and periodic motions. A helical pair was used to adjust the location of the spring. In this way,a simple butefficient technique to control and anti-control chaos was created,which was proved by the phase diagram and thelargest Lyapunov exponent.
2013, 32(1): 6-10.
Abstract:
Combining finite rotational tensor(FRT),sensitivity analysis and multi-island genetic algorithm(MI-GA),the paper aims at the design and optimization of the steering mechanism of a three-axle similar rhombic vehi-cle. Then it establishes its kinematics numerical model based on FRT,and made sensitivity analysis of its relatedhard points. With sensitivity analysis results as optimization variables,the minimum characterization value of thefront and rear wheels' steering synchronization as optimization target,it uses the MIGA as the tool to optimize thetarget. After optimization, the target value drops from the initial 7. 789�to 1. 210� thus tire wear is reduced. Theoptimization results show that the method can be used to design the steering mechanism of the vehicle.
Combining finite rotational tensor(FRT),sensitivity analysis and multi-island genetic algorithm(MI-GA),the paper aims at the design and optimization of the steering mechanism of a three-axle similar rhombic vehi-cle. Then it establishes its kinematics numerical model based on FRT,and made sensitivity analysis of its relatedhard points. With sensitivity analysis results as optimization variables,the minimum characterization value of thefront and rear wheels' steering synchronization as optimization target,it uses the MIGA as the tool to optimize thetarget. After optimization, the target value drops from the initial 7. 789�to 1. 210� thus tire wear is reduced. Theoptimization results show that the method can be used to design the steering mechanism of the vehicle.
2013, 32(1): 11-15.
Abstract:
In this paper,curved beam element model was proposed in order to improve the computational accuracyand efficiency of a curved beam multibody system with large deformation. By using arc coordinate and curved beamelements,dynamic model of curved beam multibody system was established based on absolute coordinate formula-tion,which takes into account geometric nonlinear effect. The advantage of the model is that the transformation ma-trices are not needed. Furthermore,the convergence of the curved beam element model is better than that of theconventional straight beam model. Simulation of a single curved beam pendulum was carried out to show the accura-cy and efficiency of the curved beam element model by comparison with the simulation results obtained from thestraight beam element model. Finally,the curved beam element model was used to simulate a four-bar mechanismwith large deformation.
In this paper,curved beam element model was proposed in order to improve the computational accuracyand efficiency of a curved beam multibody system with large deformation. By using arc coordinate and curved beamelements,dynamic model of curved beam multibody system was established based on absolute coordinate formula-tion,which takes into account geometric nonlinear effect. The advantage of the model is that the transformation ma-trices are not needed. Furthermore,the convergence of the curved beam element model is better than that of theconventional straight beam model. Simulation of a single curved beam pendulum was carried out to show the accura-cy and efficiency of the curved beam element model by comparison with the simulation results obtained from thestraight beam element model. Finally,the curved beam element model was used to simulate a four-bar mechanismwith large deformation.
2013, 32(1): 16-21.
Abstract:
The fuzzy job-shop scheduling problem is studied in this paper. Fuzzy processing times were denoted bytriangular fuzzy numbers and fuzzy due dates were presented by half trapezoid fuzzy numbers. Based on the agree-ment index to maximize the minimum customer satisfaction,the model of fuzzy job-shop scheduling problem wasproposed. Furthermore,a new adaptive genetic algorithm was proposed,which promoted the coding efficiency byutilizing the coding method based on preferred list. Also,elitism preservation was adopted in the evolution processand adaptive crossover-mutation operator was improved so that the optimum individual can participate in the evolu-tion. At last,the improvement of the new algorithm in both search ability and convergence performance were veri-fied by the simulation results.
The fuzzy job-shop scheduling problem is studied in this paper. Fuzzy processing times were denoted bytriangular fuzzy numbers and fuzzy due dates were presented by half trapezoid fuzzy numbers. Based on the agree-ment index to maximize the minimum customer satisfaction,the model of fuzzy job-shop scheduling problem wasproposed. Furthermore,a new adaptive genetic algorithm was proposed,which promoted the coding efficiency byutilizing the coding method based on preferred list. Also,elitism preservation was adopted in the evolution processand adaptive crossover-mutation operator was improved so that the optimum individual can participate in the evolu-tion. At last,the improvement of the new algorithm in both search ability and convergence performance were veri-fied by the simulation results.
2013, 32(1): 22-27.
Abstract:
In order to improve the rigidity of the mechanism,some extra constraint structures are attached in itwhile the statically indeterminate problem may be arised in analyzing the statics of the mechanism at the same time.The dynamic statics of a novel toggle press was analyzed. Aiming at the static indeterminate problem,the mecha-nism was divided into a statically determinate sub-mechanism and a statically indeterminate sub-mechanism,andthe latter was also translated into an equivalent mechanism,by whose kinematic constraint equations,the deforma-tion coordination equation of the system was finally found. Compared with general approaches to solve the staticallyindeterminate problem,the deformation coordination equation obtained by this method has a simpler and linearform,which makes it easier to be solved.
In order to improve the rigidity of the mechanism,some extra constraint structures are attached in itwhile the statically indeterminate problem may be arised in analyzing the statics of the mechanism at the same time.The dynamic statics of a novel toggle press was analyzed. Aiming at the static indeterminate problem,the mecha-nism was divided into a statically determinate sub-mechanism and a statically indeterminate sub-mechanism,andthe latter was also translated into an equivalent mechanism,by whose kinematic constraint equations,the deforma-tion coordination equation of the system was finally found. Compared with general approaches to solve the staticallyindeterminate problem,the deformation coordination equation obtained by this method has a simpler and linearform,which makes it easier to be solved.
2013, 32(1): 28-31.
Abstract:
A 3-RPS-type parallel robot has three structurally symmetrical branch-chain,each of which consists of arevolute pair and prismatic pair,spherical pair. The revolute pair is connected with the base; the spherical pair isconnected with the moving platform; revolute and spherical pairs are connected with a prismatic pair. This paper ana-lyzed the degrees of freedom of a 3-RPS-type parallel robot based on the screw theory, and used anti-screw the meth-od to establish the constraint Jacobian matrix, the motion Jacobian matrix and the complete Jacobian matrix; with themethod the mapping between the motion speed of a moving platform and the speed of an actuation joint was derived;the velocity and acceleration of the end-executor was calculated and the singularity was anslyzed. Matlab SimMechan-ics was used to establish the simulation model of the 3-RPS-type parallel robot to perform kinematics simulation andcomparative study. The results show that with the changes in the actual outputs of the moving platform are basicallyconsistent with those in the given reference value,and the correctness of the modeling method is verified.
A 3-RPS-type parallel robot has three structurally symmetrical branch-chain,each of which consists of arevolute pair and prismatic pair,spherical pair. The revolute pair is connected with the base; the spherical pair isconnected with the moving platform; revolute and spherical pairs are connected with a prismatic pair. This paper ana-lyzed the degrees of freedom of a 3-RPS-type parallel robot based on the screw theory, and used anti-screw the meth-od to establish the constraint Jacobian matrix, the motion Jacobian matrix and the complete Jacobian matrix; with themethod the mapping between the motion speed of a moving platform and the speed of an actuation joint was derived;the velocity and acceleration of the end-executor was calculated and the singularity was anslyzed. Matlab SimMechan-ics was used to establish the simulation model of the 3-RPS-type parallel robot to perform kinematics simulation andcomparative study. The results show that with the changes in the actual outputs of the moving platform are basicallyconsistent with those in the given reference value,and the correctness of the modeling method is verified.
2013, 32(1): 32-36.
Abstract:
The aerodynamic design of carrier rocket is facing the combinatorial explosion problem caused by modu-lar design. In order to improve the efficiency of design and simulation,a rocket aerodynamic configuration integrat-ed design system (RACIDS) was established. Firstly, system overall architecture was planned. The four-layer openarchitecture and the workflow of the software were designed. Secondly,on the basis of classification of aerodynamicdesign parameters,the design template library was established. Functions such as parametric geometry modelingand model interference checking were implemented by the secondary development of Pro/E. Scripts for generatingparametric mesh model were written in Python language. By applying CFD-GEOM,Gambit and Fluent,automatedsimulation process was achieved. Thirdly, a graphical user interface (GUI) was developed using VC ++6. 0; basedon the GUI the design process,research data and application tools were integrated. Finally,the correctness and ef-fectiveness of RACIDS were validated with one carrier rocket application example.
The aerodynamic design of carrier rocket is facing the combinatorial explosion problem caused by modu-lar design. In order to improve the efficiency of design and simulation,a rocket aerodynamic configuration integrat-ed design system (RACIDS) was established. Firstly, system overall architecture was planned. The four-layer openarchitecture and the workflow of the software were designed. Secondly,on the basis of classification of aerodynamicdesign parameters,the design template library was established. Functions such as parametric geometry modelingand model interference checking were implemented by the secondary development of Pro/E. Scripts for generatingparametric mesh model were written in Python language. By applying CFD-GEOM,Gambit and Fluent,automatedsimulation process was achieved. Thirdly, a graphical user interface (GUI) was developed using VC ++6. 0; basedon the GUI the design process,research data and application tools were integrated. Finally,the correctness and ef-fectiveness of RACIDS were validated with one carrier rocket application example.
2013, 32(1): 37-41.
Abstract:
Characters of process knowledge were analyzed for the integration and application of new process knowl-edge base system and legacy engineering design systems. On the basis of analyzing the integrating and applyingprocess,a loosely-coupled mode of process knowledge integration and application was built based on process knowl-edge service bus and common data platform. The solution for the integration of fabrication order design knowledgebase system and computer aided process planning system was presented. It was shown that loosely-coupled knowl-edge integration can be achieved by the proposed approach,and both new and existing knowledge can be effectivelyutilized to design fabrication order rapidly and normatively.
Characters of process knowledge were analyzed for the integration and application of new process knowl-edge base system and legacy engineering design systems. On the basis of analyzing the integrating and applyingprocess,a loosely-coupled mode of process knowledge integration and application was built based on process knowl-edge service bus and common data platform. The solution for the integration of fabrication order design knowledgebase system and computer aided process planning system was presented. It was shown that loosely-coupled knowl-edge integration can be achieved by the proposed approach,and both new and existing knowledge can be effectivelyutilized to design fabrication order rapidly and normatively.
2013, 32(1): 42-46.
Abstract:
The paper studied the problem of mobile robot path planning under dynamic environment. Grid methodwas used to establish workspace model of the mobile robot. The artificial potential field concept which makes antsmore sensitive to the optimal path was introduced into the ant colony algorithm during the global searching process.The mobile robot carries out different obstacle avoidance strategies respectively when different types of obstacle ap-pear in the dynamic environment. Meanwhile an optimal path prediction model was proposed to predict if there is abetter path in the process of obstacle avoidance. This algorithm combined the characteristics of artificial potentialfield method with ant colony algorithm, integrated the global path planning and the local path planning so as to im-prove path searching efficiency. The simulation results indicate the validity of the algorithm.
The paper studied the problem of mobile robot path planning under dynamic environment. Grid methodwas used to establish workspace model of the mobile robot. The artificial potential field concept which makes antsmore sensitive to the optimal path was introduced into the ant colony algorithm during the global searching process.The mobile robot carries out different obstacle avoidance strategies respectively when different types of obstacle ap-pear in the dynamic environment. Meanwhile an optimal path prediction model was proposed to predict if there is abetter path in the process of obstacle avoidance. This algorithm combined the characteristics of artificial potentialfield method with ant colony algorithm, integrated the global path planning and the local path planning so as to im-prove path searching efficiency. The simulation results indicate the validity of the algorithm.
2013, 32(1): 47-50.
Abstract:
Based on the fact that some traction engine gears often have tooth surface veneer and pitting problems,thegear contact parameters including the contact ratio, tooth contact stress and tooth root bending stress were optimized byusing the multi-objective genetic algorithm,then optimized the gear contact parameters. In order to save calculationcosts, surrogate model of contact stress and root bending stress were established based on simulations of gears parameter-ized finite element model. The result shows that the genetic algorithm can search pareto solution sets fast and effectivelyin many dimensions regional,and realizes the multi-objective optimization. Using the optimized parameters, the von mi-ses stress by finite element software were simulated, and the stress of optimized gear can be effectively decreased.
Based on the fact that some traction engine gears often have tooth surface veneer and pitting problems,thegear contact parameters including the contact ratio, tooth contact stress and tooth root bending stress were optimized byusing the multi-objective genetic algorithm,then optimized the gear contact parameters. In order to save calculationcosts, surrogate model of contact stress and root bending stress were established based on simulations of gears parameter-ized finite element model. The result shows that the genetic algorithm can search pareto solution sets fast and effectivelyin many dimensions regional,and realizes the multi-objective optimization. Using the optimized parameters, the von mi-ses stress by finite element software were simulated, and the stress of optimized gear can be effectively decreased.
2013, 32(1): 51-53.
Abstract:
The effect of annealing time on morphology,structure,ultraviolet-visible transmittance,band gap andmid-infrared transmittance of Cu-Al-O thin films was investigated by preparing and annealing the films. The resultsshow that crystallization appears with the increasing of annealing time while cracks exists and AlCu phase arises inCu-Al-O thin film annealed for 5. 0 h. The ultraviolet-visible transmittance decreases with increasing annealingtime. Mid-infrared transmittance increases initially and then decreases with the increasing of annealing time. Be-sides,the direct band gap of Cu-Al-O thin films decreases with the increasing of annealing time.
The effect of annealing time on morphology,structure,ultraviolet-visible transmittance,band gap andmid-infrared transmittance of Cu-Al-O thin films was investigated by preparing and annealing the films. The resultsshow that crystallization appears with the increasing of annealing time while cracks exists and AlCu phase arises inCu-Al-O thin film annealed for 5. 0 h. The ultraviolet-visible transmittance decreases with increasing annealingtime. Mid-infrared transmittance increases initially and then decreases with the increasing of annealing time. Be-sides,the direct band gap of Cu-Al-O thin films decreases with the increasing of annealing time.
2013, 32(1): 54-58.
Abstract:
To optimize three-dimensional path of wheeled robot,the special three-dimensional space-efficient pathwas designed,and adaptive ant colony system algorithm (AACS) was proposed to be applied to three-dimensionalspace path planning; the space between initial location point of wheeled robot and purpose point was divided intothree-dimensional grid with a slope angle,and the effective path was defined to make a TSP model. Adaptive antcolony system algorithm searches the shortest path from initial point to destination point as TSP model. Experimentsshow that AACS overcomes the shortcoming of traditional ant colony algorithm of being easily trapped to local mini-ma,the search of poor quality and accuracy. AACS improves the convergence speed and accuracy,outputs stabili-ty,and solve three-dimensional path optimization problem for wheeled robots in practice.
To optimize three-dimensional path of wheeled robot,the special three-dimensional space-efficient pathwas designed,and adaptive ant colony system algorithm (AACS) was proposed to be applied to three-dimensionalspace path planning; the space between initial location point of wheeled robot and purpose point was divided intothree-dimensional grid with a slope angle,and the effective path was defined to make a TSP model. Adaptive antcolony system algorithm searches the shortest path from initial point to destination point as TSP model. Experimentsshow that AACS overcomes the shortcoming of traditional ant colony algorithm of being easily trapped to local mini-ma,the search of poor quality and accuracy. AACS improves the convergence speed and accuracy,outputs stabili-ty,and solve three-dimensional path optimization problem for wheeled robots in practice.
2013, 32(1): 59-62.
Abstract:
A finite element model was developed to simulating the strain in orthogonal cutting process based on thematerial model,fracture criterion and contact relationship between cutter and workpiece. According to analysis re-sults of FEM,three deformation zones and two side direction strains were analyzed; and two side direction burrswere formed as results of two side direction strain. Finished surface material becomes affected layer due to primarydeformation zone and third deformation zone. Cutting layer material becomes chip in primary deformation zone andsecond deformation zones,and the strain distribution of chip was determined by these two deformation zones. Finiteelement model generated here provided a numerical analysis method to study the burr formation mechanism,affect-ed layer and strain of chip.
A finite element model was developed to simulating the strain in orthogonal cutting process based on thematerial model,fracture criterion and contact relationship between cutter and workpiece. According to analysis re-sults of FEM,three deformation zones and two side direction strains were analyzed; and two side direction burrswere formed as results of two side direction strain. Finished surface material becomes affected layer due to primarydeformation zone and third deformation zone. Cutting layer material becomes chip in primary deformation zone andsecond deformation zones,and the strain distribution of chip was determined by these two deformation zones. Finiteelement model generated here provided a numerical analysis method to study the burr formation mechanism,affect-ed layer and strain of chip.
2013, 32(1): 63-66.
Abstract:
According to the crashworthiness requirement of vehicle frontal rail,a combined beam which was filledwith a group of circular tubes in rectangular tube was designed. Energy-absorbing and deformation characteristics ofthe combined beam subjected to axial impacting loads were studied. The influences of circular tube diameter andcircular tube length change on combined beam's performance were studied. Research results show that the crash-worthiness of the combined beam is greatly improved after being filled with a group of circular tubes. Moreover, im-pact peak loads and mean loads could be adjusted in the crushing process through changing circular tube diameterand circular tube length. Thus the structural crashworthiness could be improved further.
According to the crashworthiness requirement of vehicle frontal rail,a combined beam which was filledwith a group of circular tubes in rectangular tube was designed. Energy-absorbing and deformation characteristics ofthe combined beam subjected to axial impacting loads were studied. The influences of circular tube diameter andcircular tube length change on combined beam's performance were studied. Research results show that the crash-worthiness of the combined beam is greatly improved after being filled with a group of circular tubes. Moreover, im-pact peak loads and mean loads could be adjusted in the crushing process through changing circular tube diameterand circular tube length. Thus the structural crashworthiness could be improved further.
2013, 32(1): 67-70.
Abstract:
In order to study the vibration-reduction capability when submarine structures connected by rubber pad,the rigid and the rubber pad connecting plate and shell coupled simulations were calculated by the FEM softwareANSYS respectively. Then the vibration responses of the two different coupled simulations were compared. Moreo-ver the influence of rubber pad parameters on vibration responses was analyzed. In the paper two different rubberpads,damping rubber pad and grooved rubber pad were used. The vibration responses of shell using different rub-ber pads were compared. Simulation results show: firstly,the vibration transmission between plate and shell couldbe efficiently controlled by rubber pad connection; secondly,the vibration isolation effect of grooved rubber padwas better than damping rubber pad.
In order to study the vibration-reduction capability when submarine structures connected by rubber pad,the rigid and the rubber pad connecting plate and shell coupled simulations were calculated by the FEM softwareANSYS respectively. Then the vibration responses of the two different coupled simulations were compared. Moreo-ver the influence of rubber pad parameters on vibration responses was analyzed. In the paper two different rubberpads,damping rubber pad and grooved rubber pad were used. The vibration responses of shell using different rub-ber pads were compared. Simulation results show: firstly,the vibration transmission between plate and shell couldbe efficiently controlled by rubber pad connection; secondly,the vibration isolation effect of grooved rubber padwas better than damping rubber pad.
2013, 32(1): 71-76.
Abstract:
To estimate the influence of joint clearance on cutter's spatial position and orientation (collectively re-ferred to as pose) for 6-DOFs parallel machine tool, a decomposition-intersection method was proposed in this studyto obtain the error space caused by joint clearance. Based on the screw theory and exponential coordinate,the for-ward kinematics model was established and the analytic expression was derived for each link of the parallel machinetool. Then six reachable spaces,each corresponding to the situation that the cutter-platform is constrained by onlyone link,were calculated and the intersection of them,i. e.,cutter's error space caused by joint clearance was ob-tained. The experiment and analysis on practical parallel machine tool proved the correctness and effectiveness ofthe proposed method.
To estimate the influence of joint clearance on cutter's spatial position and orientation (collectively re-ferred to as pose) for 6-DOFs parallel machine tool, a decomposition-intersection method was proposed in this studyto obtain the error space caused by joint clearance. Based on the screw theory and exponential coordinate,the for-ward kinematics model was established and the analytic expression was derived for each link of the parallel machinetool. Then six reachable spaces,each corresponding to the situation that the cutter-platform is constrained by onlyone link,were calculated and the intersection of them,i. e.,cutter's error space caused by joint clearance was ob-tained. The experiment and analysis on practical parallel machine tool proved the correctness and effectiveness ofthe proposed method.
2013, 32(1): 77-80.
Abstract:
The forward and backward waves in the adjacent layers were related by a scattering matrix (SM). Thetransmittance and reflectance of one-dimensional perfect and defective phononic crystal (PnC) were calculated byusing of SM method (SMM),and the results are identical with those of transfer matrix method (TMM). Further-more,for normal incident elastic wave,the transmittance of PnC hetero-structures with two sub-PnCs,which arecomposed of same media with different periodic constant and different media with same periodic constant,were ob-served respectively. The results suggest that the locally resonant modes should be strengthened in band-gaps and thenumber of the resonant modes should be determined by the periodic number of the last PnC.
The forward and backward waves in the adjacent layers were related by a scattering matrix (SM). Thetransmittance and reflectance of one-dimensional perfect and defective phononic crystal (PnC) were calculated byusing of SM method (SMM),and the results are identical with those of transfer matrix method (TMM). Further-more,for normal incident elastic wave,the transmittance of PnC hetero-structures with two sub-PnCs,which arecomposed of same media with different periodic constant and different media with same periodic constant,were ob-served respectively. The results suggest that the locally resonant modes should be strengthened in band-gaps and thenumber of the resonant modes should be determined by the periodic number of the last PnC.
2013, 32(1): 81-85.
Abstract:
The vibration signals of gear pump include much noise that must be eliminated before application. De-noising algorithm based on traditional wavelet threshold may produce discontinuities in singularity point of signal. Anew wavelet threshold function was used against the shortcomings of soft and hard threshold function. An improvedde-noising method was put forward by combining new threshold function and translation-invariant de-noising meth-od. The method can overcome the disadvantages of soft and hard threshold de-noising methods and suppress thePseudo-Gibbs phenomena caused by threshold de-noising methods. The experimental results show that the presentmethod has better de-noising effect than conventional threshold de-noising methods,and can be applied to denoisethe vibration signal of gear pump.
The vibration signals of gear pump include much noise that must be eliminated before application. De-noising algorithm based on traditional wavelet threshold may produce discontinuities in singularity point of signal. Anew wavelet threshold function was used against the shortcomings of soft and hard threshold function. An improvedde-noising method was put forward by combining new threshold function and translation-invariant de-noising meth-od. The method can overcome the disadvantages of soft and hard threshold de-noising methods and suppress thePseudo-Gibbs phenomena caused by threshold de-noising methods. The experimental results show that the presentmethod has better de-noising effect than conventional threshold de-noising methods,and can be applied to denoisethe vibration signal of gear pump.
2013, 32(1): 86-90.
Abstract:
To investigate the steering characteristics of the automobile steering system,a Modelica-based modelingapproach for vehicle steering system was proposed. On the basis of dynamics analysis,steering system module,ve-hicle module,tire module and the torque calculation module were modeled in multi-domain unified modeling lan-guage-Modelica. In the simulation platform-Dymola,the whole simulation model for the steering system was con-structed by connecting those modules according to their interactional relations. An automobile steering system pa-rameter measurement test bench was set up for a commercial vehicle hydraulic power steering system,and thosemodel parameters were measured through the bench tests. The comparison between simulation results based on thewhole simulation model for the steering system and actual experimental results in the spot steering situation demon-strated the feasibility of the proposed approach.
To investigate the steering characteristics of the automobile steering system,a Modelica-based modelingapproach for vehicle steering system was proposed. On the basis of dynamics analysis,steering system module,ve-hicle module,tire module and the torque calculation module were modeled in multi-domain unified modeling lan-guage-Modelica. In the simulation platform-Dymola,the whole simulation model for the steering system was con-structed by connecting those modules according to their interactional relations. An automobile steering system pa-rameter measurement test bench was set up for a commercial vehicle hydraulic power steering system,and thosemodel parameters were measured through the bench tests. The comparison between simulation results based on thewhole simulation model for the steering system and actual experimental results in the spot steering situation demon-strated the feasibility of the proposed approach.
2013, 32(1): 91-95.
Abstract:
Aiming to the complex and fuzz nature of gear pump signal,a fault diagnosis approach of Bayesian net-works was presented based on multi-sensor information fusion. Firstly,this study analyzed the signal characteristicof vibration and pressure, and extracted energy and fractal characteristis of vibration signal and high frequency pres-sure pulse of pressure signal. Then the multi-fault Bayesian network was built to fuse these characteristics. Finally,Bayesian classifier was designed to identify the fault pattern through the maximum posterior estimation. Twice fusionresults show that multi-sensor information completes the characteristic space,raises the diagnosis exactitude rate.This approach can effectively carry out the gear pump multi-fault diagnosis and have better application value.
Aiming to the complex and fuzz nature of gear pump signal,a fault diagnosis approach of Bayesian net-works was presented based on multi-sensor information fusion. Firstly,this study analyzed the signal characteristicof vibration and pressure, and extracted energy and fractal characteristis of vibration signal and high frequency pres-sure pulse of pressure signal. Then the multi-fault Bayesian network was built to fuse these characteristics. Finally,Bayesian classifier was designed to identify the fault pattern through the maximum posterior estimation. Twice fusionresults show that multi-sensor information completes the characteristic space,raises the diagnosis exactitude rate.This approach can effectively carry out the gear pump multi-fault diagnosis and have better application value.
2013, 32(1): 96-99.
Abstract:
Aiming at the non-Gaussian and non-stationary characteristics of the wind turbine vibration signals,thispaper proposed a new fault diagnosis method based on the hybrid time-frequency analysis. This new method dealedwith the raw vibration signals by the parameter optimizied Morlet wavelet de-noising method,to filter the strongbackground noise interruption. Then the auto term window method was introduced to suppress the cross terms in thetime-frequency domain, to strengthen the useful fault features, to extract the fault features and to realize the diagno-sis. In the parameter optimiziation process,the cross validation method was introduced to optimize the Morlet wave-let parameters and the scale parameter. The auto term function is designed based on the smooth pseudo Wigner-Ville distribution (SPWVD) and two threshold processes were introduced to reduce the computation and enhancethe computing efficiency. The wind turbine vibration signal analysis proved that this new method can not only sup-press the noise interruption in the background,but also realize the fault diagnosis efficiently.
Aiming at the non-Gaussian and non-stationary characteristics of the wind turbine vibration signals,thispaper proposed a new fault diagnosis method based on the hybrid time-frequency analysis. This new method dealedwith the raw vibration signals by the parameter optimizied Morlet wavelet de-noising method,to filter the strongbackground noise interruption. Then the auto term window method was introduced to suppress the cross terms in thetime-frequency domain, to strengthen the useful fault features, to extract the fault features and to realize the diagno-sis. In the parameter optimiziation process,the cross validation method was introduced to optimize the Morlet wave-let parameters and the scale parameter. The auto term function is designed based on the smooth pseudo Wigner-Ville distribution (SPWVD) and two threshold processes were introduced to reduce the computation and enhancethe computing efficiency. The wind turbine vibration signal analysis proved that this new method can not only sup-press the noise interruption in the background,but also realize the fault diagnosis efficiently.
2013, 32(1): 100-104.
Abstract:
In order to improve the capability of small and medium enterprises to design new products,the meshingof three-blade root blower was analyzed in detail, and a convenient way to design the blade shape of a rotor was pro-posed. Firstly,the pitch pressure angle according to the radius of base circle and center distance was determined;secondly,involute meshing rotor's start and end points were determined; thirdly,the roll angle of involutes' lineoccurred on the base circle was determined; fourthly, the rotor involutes' position was determined. Then, accordingto R0 =2Z(R-a)·ξ/π (0.787 8≤ξ≤0. 927 7),based on the best area utilization factor,the optimal value of R0 was determind by modern optimization algorithms. Finally,taking 3L4 series roots blower as example,details ofthe rotor design and optimization solution process was introduced.
In order to improve the capability of small and medium enterprises to design new products,the meshingof three-blade root blower was analyzed in detail, and a convenient way to design the blade shape of a rotor was pro-posed. Firstly,the pitch pressure angle according to the radius of base circle and center distance was determined;secondly,involute meshing rotor's start and end points were determined; thirdly,the roll angle of involutes' lineoccurred on the base circle was determined; fourthly, the rotor involutes' position was determined. Then, accordingto R0 =2Z(R-a)·ξ/π (0.787 8≤ξ≤0. 927 7),based on the best area utilization factor,the optimal value of R0 was determind by modern optimization algorithms. Finally,taking 3L4 series roots blower as example,details ofthe rotor design and optimization solution process was introduced.
2013, 32(1): 105-110,115.
Abstract:
In order to improve the performance of trajectory tracking controller for multi-links robot,a feedback lin-earization double fuzzy sliding mode controller was proposed in this paper. The nonlinear dynamic model of multi-links robot was linearized based on the feedback linearization technique,and a double fuzzy sliding model controllerwas designed. To get faster response speed,a fuzzy controller was designed to adaptively tune the slope of slidingmode surface. To reduce the chattering of sliding mode control,another fuzzy control was designed to adaptivelytune the switch part of sliding mode control. The system stability was proved by using the Lyapunov principle. Theproposed controllers were used in trajectory control of a three degrees of freedom spatial robot,and the resultsshowed the validity of the control scheme.
In order to improve the performance of trajectory tracking controller for multi-links robot,a feedback lin-earization double fuzzy sliding mode controller was proposed in this paper. The nonlinear dynamic model of multi-links robot was linearized based on the feedback linearization technique,and a double fuzzy sliding model controllerwas designed. To get faster response speed,a fuzzy controller was designed to adaptively tune the slope of slidingmode surface. To reduce the chattering of sliding mode control,another fuzzy control was designed to adaptivelytune the switch part of sliding mode control. The system stability was proved by using the Lyapunov principle. Theproposed controllers were used in trajectory control of a three degrees of freedom spatial robot,and the resultsshowed the validity of the control scheme.
2013, 32(1): 111-115.
Abstract:
This paper presented a flexible manipulator joint driven by air cylinder,using plate spring as the frame-work. The deformation of the plate spring was equivalent to the large deformation of a elastic cantilever beam actedon cantilevered end by special varying load,whose magnitude and direction varied with the cylinder pressure. Stat-ic model of the cantilever beam bend was built and its differential equation was given. Numerical solutions to platespring's flexion angle,deformation displacement and stress under various pressures were calculated by solving thedifferential equation. Moreover,the deformation curve and stress curve were drawn,and the distribution of themwas analyzed. The maximum stress was got and checked.
This paper presented a flexible manipulator joint driven by air cylinder,using plate spring as the frame-work. The deformation of the plate spring was equivalent to the large deformation of a elastic cantilever beam actedon cantilevered end by special varying load,whose magnitude and direction varied with the cylinder pressure. Stat-ic model of the cantilever beam bend was built and its differential equation was given. Numerical solutions to platespring's flexion angle,deformation displacement and stress under various pressures were calculated by solving thedifferential equation. Moreover,the deformation curve and stress curve were drawn,and the distribution of themwas analyzed. The maximum stress was got and checked.
2013, 32(1): 116-119,125.
Abstract:
According the structural elements of the gear such as wheel boss,web,and wheel flange,we simplify itas an annular plate with stepped variable thickness,and calculate its natural frequency based on the Mindlin theoryfor moderate-thick plates. The gear's natural frequency obtained by theoretical model is consistent with that of finiteelement. By many calculation examples,we found that the main factors which affect the accuracy of the calculationare the ratio of thickness to diameter and the thickness ratio of wheel boss to web. In the application range of themoderate-thick plates theory,i. e. the ratio of thickness to diameter is less then 0. 5,and the thickness ratio ofwheel boss to web is less then 2,the calculated results are very accurate.
According the structural elements of the gear such as wheel boss,web,and wheel flange,we simplify itas an annular plate with stepped variable thickness,and calculate its natural frequency based on the Mindlin theoryfor moderate-thick plates. The gear's natural frequency obtained by theoretical model is consistent with that of finiteelement. By many calculation examples,we found that the main factors which affect the accuracy of the calculationare the ratio of thickness to diameter and the thickness ratio of wheel boss to web. In the application range of themoderate-thick plates theory,i. e. the ratio of thickness to diameter is less then 0. 5,and the thickness ratio ofwheel boss to web is less then 2,the calculated results are very accurate.
2013, 32(1): 120-125.
Abstract:
The spectrometric oil analysis (SOA) is an important technique for aircraft engine state monitoring andfault diagnosis,and forecasting aircraft engine state through SOA results has an advantage of finding out aircraft en-gine wear fault early. According to the characteristics of the SOA data,the combinational forecast model was set upbased on the least squares support vector machine after Auto Regressive (AR) model,GM(1, 1) model and backpropagation(BP) neural network model. In addition,the particle swarm algorithm was used to optimize the regular-ization parameter of least squares support vector machines(LSSVM) and the parameter of kernel function. Finally,two time series of SOA data were used to verify this model. By comparying with the foundation models,the result ofcombinational forecasting model shows better effect and higher precision of forecast by using the non-linear variableweight and the least squares support vector machines with particle swarm optimization.
The spectrometric oil analysis (SOA) is an important technique for aircraft engine state monitoring andfault diagnosis,and forecasting aircraft engine state through SOA results has an advantage of finding out aircraft en-gine wear fault early. According to the characteristics of the SOA data,the combinational forecast model was set upbased on the least squares support vector machine after Auto Regressive (AR) model,GM(1, 1) model and backpropagation(BP) neural network model. In addition,the particle swarm algorithm was used to optimize the regular-ization parameter of least squares support vector machines(LSSVM) and the parameter of kernel function. Finally,two time series of SOA data were used to verify this model. By comparying with the foundation models,the result ofcombinational forecasting model shows better effect and higher precision of forecast by using the non-linear variableweight and the least squares support vector machines with particle swarm optimization.
2013, 32(1): 126-129,135.
Abstract:
According to the characteristics of noise and the pixel correlation of image,a valid filtering algorithm forremoving mixed noise in digital image is proposed in this paper. The algorithm can detect impulse noise accuratelyaccording to the characteristics that image pixels contaminated by impulse noise are significantly different from mostof the pixels of its neighborhood in brightness,and then the authors tooe the median filtering algorithm to filter thedetected impulse noise using those pixels which are not contaminated in filtering window. Because the processedimpulse noise and it's neighborhood impulse noise are all not attended filtering operation,thus a good protection ofthe detail of the image was implemented. Afterwards,for removing Gaussian noise in image,the paper proposed animproved weighted average filtering algorithm. The algorithm considers not only gray correlation but also positioncorrelation of pixels in defining correlation function. The experimental results show that the proposed mixed filteringalgorithm not only can filter out the mixed noise in image effectively but also can protect image detail well.
According to the characteristics of noise and the pixel correlation of image,a valid filtering algorithm forremoving mixed noise in digital image is proposed in this paper. The algorithm can detect impulse noise accuratelyaccording to the characteristics that image pixels contaminated by impulse noise are significantly different from mostof the pixels of its neighborhood in brightness,and then the authors tooe the median filtering algorithm to filter thedetected impulse noise using those pixels which are not contaminated in filtering window. Because the processedimpulse noise and it's neighborhood impulse noise are all not attended filtering operation,thus a good protection ofthe detail of the image was implemented. Afterwards,for removing Gaussian noise in image,the paper proposed animproved weighted average filtering algorithm. The algorithm considers not only gray correlation but also positioncorrelation of pixels in defining correlation function. The experimental results show that the proposed mixed filteringalgorithm not only can filter out the mixed noise in image effectively but also can protect image detail well.
2013, 32(1): 130-135.
Abstract:
By using CATIA software, 3D model of DL503 working devices was established. Then in order to simu-late whole working device system,we converted the 3D model document into an acceptable type to import in AD-AMS environment. To optimize the bucked translation,firstly,key points of the model were defined as design vari-ables and bucket translation as objective function. Secondly,boundary constraint functions and performance con-straint functions were established. Finally,by optimization analysis,the optimized scheme and curves for buckettranslation were obtained. From the curves,we can see that bucket swing angle has been greatly reduced,andtranslation performance has been improved.
By using CATIA software, 3D model of DL503 working devices was established. Then in order to simu-late whole working device system,we converted the 3D model document into an acceptable type to import in AD-AMS environment. To optimize the bucked translation,firstly,key points of the model were defined as design vari-ables and bucket translation as objective function. Secondly,boundary constraint functions and performance con-straint functions were established. Finally,by optimization analysis,the optimized scheme and curves for buckettranslation were obtained. From the curves,we can see that bucket swing angle has been greatly reduced,andtranslation performance has been improved.
2013, 32(1): 136-139,145.
Abstract:
The temperature filed, residual stress field and deformation filed of TRT volute were stimulated using thefinite element method under the condition of the hot steady-state operation. The results show that the equivalentstress of the whole TRT volute is not big when temperature load caused thermal expansion. Most of the region is be-low 100 MPa. The equivalent stress is concentrated and is about 70 MPa,and a maximum of 117 MPa appeares inthe steel plate local pointed place. The whole TRT volute maximum equivalent stress is 168 MPa which is far smal-ler than the yield stress, so it meets the required strength. The axial contraction of TRT volute is in large quantitieswhich contract in 1. 711 mm in the exhaust room and board. Contraction deformation is not great. Therefore,in thesteady-state operation process,the stiffness of TRT volute is enough.
The temperature filed, residual stress field and deformation filed of TRT volute were stimulated using thefinite element method under the condition of the hot steady-state operation. The results show that the equivalentstress of the whole TRT volute is not big when temperature load caused thermal expansion. Most of the region is be-low 100 MPa. The equivalent stress is concentrated and is about 70 MPa,and a maximum of 117 MPa appeares inthe steel plate local pointed place. The whole TRT volute maximum equivalent stress is 168 MPa which is far smal-ler than the yield stress, so it meets the required strength. The axial contraction of TRT volute is in large quantitieswhich contract in 1. 711 mm in the exhaust room and board. Contraction deformation is not great. Therefore,in thesteady-state operation process,the stiffness of TRT volute is enough.
2013, 32(1): 140-145.
Abstract:
The spectrometric oil analysis (SOA) is an important technique for aircraft engine state monitoring andfault diagnosis,and forecasting aircraft engine state through SOA results has an advantage of finding out aircraft en-gine wear fault early. According to the characteristics of the SOA data,the combinational forecast model was set upbased on the least squares support vector machine after Auto Regressive (AR) model,GM(1, 1) model and backpropagation(BP) neural network model. In addition,the particle swarm algorithm was used to optimize the regular-ization parameter of least squares support vector machines(LSSVM) and the parameter of kernel function. Finally,two time series of SOA data were used to verify this model. By comparying with the foundation models,the result ofcombinational forecasting model shows better effect and higher precision of forecast by using the non-linear variableweight and the least squares support vector machines with particle swarm optimization.
The spectrometric oil analysis (SOA) is an important technique for aircraft engine state monitoring andfault diagnosis,and forecasting aircraft engine state through SOA results has an advantage of finding out aircraft en-gine wear fault early. According to the characteristics of the SOA data,the combinational forecast model was set upbased on the least squares support vector machine after Auto Regressive (AR) model,GM(1, 1) model and backpropagation(BP) neural network model. In addition,the particle swarm algorithm was used to optimize the regular-ization parameter of least squares support vector machines(LSSVM) and the parameter of kernel function. Finally,two time series of SOA data were used to verify this model. By comparying with the foundation models,the result ofcombinational forecasting model shows better effect and higher precision of forecast by using the non-linear variableweight and the least squares support vector machines with particle swarm optimization.
2013, 32(1): 146-149,156.
Abstract:
In order to improve stamping forming efficiency and quality of an electronic component,the finite ele-ment models of workpiece and punch-matrix were established according to contact-impact algorithm along with con-tact pair. Then simulation analysis was carried out based on LS-DYNA contact-impact algorithm. In the analysis,the force and motion transmission between punch-matrix and workpiece were realized through the contact-impact in-terface defined. Strain-stress figure and forming limit diagram were obtained. Analysis results indicate that theforming property of workpiece was fine. In addition, this method can realize the checkout of stamping forming quali-ty. And the optimal forming factors,clearance and velocity of punch-matrix were obtained by adjusting the analysisinput parameters. The obtained results are well in agreement with practical product data.
In order to improve stamping forming efficiency and quality of an electronic component,the finite ele-ment models of workpiece and punch-matrix were established according to contact-impact algorithm along with con-tact pair. Then simulation analysis was carried out based on LS-DYNA contact-impact algorithm. In the analysis,the force and motion transmission between punch-matrix and workpiece were realized through the contact-impact in-terface defined. Strain-stress figure and forming limit diagram were obtained. Analysis results indicate that theforming property of workpiece was fine. In addition, this method can realize the checkout of stamping forming quali-ty. And the optimal forming factors,clearance and velocity of punch-matrix were obtained by adjusting the analysisinput parameters. The obtained results are well in agreement with practical product data.
2013, 32(1): 150-156.
Abstract:
It is pivotal for dynamic optimization design of truck cranes to research their dynamical characteristics.Firstly,a kind of truck crane was equivalent to a multi-rigid-flexible-body system including flexible boom by usingthe Multi-body System Transfer Matrix Method in this paper. Its frequency response was researched as well. Sec-ondly,the dynamic impact response could be calculated by analyzing the impact occurring in the beginning of hoist-ing. At last, the equations used for dynamic stress analysis were gotten by investigating the relation between dynam-ic stress and elastic displacements. Afterwards,the dynamic stress of flexible boom being affected by impact at thebeginning of hoisting was calculated dispending on these equations,which was compared with experimental result.And the effects to maximum dynamical stress of different attenuate coefficients of electromotor were investigated.
It is pivotal for dynamic optimization design of truck cranes to research their dynamical characteristics.Firstly,a kind of truck crane was equivalent to a multi-rigid-flexible-body system including flexible boom by usingthe Multi-body System Transfer Matrix Method in this paper. Its frequency response was researched as well. Sec-ondly,the dynamic impact response could be calculated by analyzing the impact occurring in the beginning of hoist-ing. At last, the equations used for dynamic stress analysis were gotten by investigating the relation between dynam-ic stress and elastic displacements. Afterwards,the dynamic stress of flexible boom being affected by impact at thebeginning of hoisting was calculated dispending on these equations,which was compared with experimental result.And the effects to maximum dynamical stress of different attenuate coefficients of electromotor were investigated.
