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RSS2014 Vol. 33, No. 11
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2014, 33(11): 1609-1613.
doi: 10.13433/j.cnki.1003-8728.2014.1101
PDF 618KB
Abstract:
A point-vector-blending interpolation method in five-axis machining is studied for meeting the requirement of the CNC development and afterward machining experiments. A double curve interpolation method based on Hermite polynomial interpolation algorithm is proposed in this paper. Though the kinematics analysis,the posture transformation and joint drive parameters of the parallel power head are discussed for interpolation. Point sets are established according to the information provided by NC codes,the linear interpolation is utilized to estimate the vector direction on every point,and the coarse interpolation is accomplished by using the Hermite algorithm. The simulations are implemented by considering the motion pattern,and results prove that the double curve interpolation algorithm can achieve better position and pose precision. Compared with the linear interpolation and the plane vector interpolation method,the double curve interpolation method satisfies the demand of the development of CNC and machining experiments.
A point-vector-blending interpolation method in five-axis machining is studied for meeting the requirement of the CNC development and afterward machining experiments. A double curve interpolation method based on Hermite polynomial interpolation algorithm is proposed in this paper. Though the kinematics analysis,the posture transformation and joint drive parameters of the parallel power head are discussed for interpolation. Point sets are established according to the information provided by NC codes,the linear interpolation is utilized to estimate the vector direction on every point,and the coarse interpolation is accomplished by using the Hermite algorithm. The simulations are implemented by considering the motion pattern,and results prove that the double curve interpolation algorithm can achieve better position and pose precision. Compared with the linear interpolation and the plane vector interpolation method,the double curve interpolation method satisfies the demand of the development of CNC and machining experiments.
2014, 33(11): 1614-1620.
doi: 10.13433/j.cnki.1003-8728.2014.1102
Abstract:
The two revolute pair clearances in the crank slider mechanism are considered. The mathematical model which describes the revolute pair clearances is introduced. A modified hybrid nonlinear spring damping collision force model is used to analyze the collision characteristics of revolute pair. The dynamics model for crank slider mechanism with two revolute pair clearance is established by using Newton Euler's method. Finally,the simulation of velocity,acceleration and contact force are developed with respect to the different values of the pair clearances. The results show that the magnitude of the pair clearance is an important element to influence the dynamic characteristic.
The two revolute pair clearances in the crank slider mechanism are considered. The mathematical model which describes the revolute pair clearances is introduced. A modified hybrid nonlinear spring damping collision force model is used to analyze the collision characteristics of revolute pair. The dynamics model for crank slider mechanism with two revolute pair clearance is established by using Newton Euler's method. Finally,the simulation of velocity,acceleration and contact force are developed with respect to the different values of the pair clearances. The results show that the magnitude of the pair clearance is an important element to influence the dynamic characteristic.
2014, 33(11): 1621-1626.
doi: 10.13433/j.cnki.1003-8728.2014.1103
Abstract:
The adhesive between robot's feet and walls,and the control strategy are two key elements in wallclimbing robots. Inspired by the beetle claws and inchworm-like motion,a flexible steerable beetle-inspired hexapod climbing robot is designed in this paper. The bionic control method,i. e. Central Pattern Generator(CPG) is used to achieve straight motion and obstacle avoidance ability. The robot foot with crawling grasping is designed to improve its climbing stability. The structure of robot is simple,and the CGP control method is simple and innovative. Based on MATLAB software,the CPG control network is constructed combined with ultrasonic sensor feedback signal. The correct control signals can be obtained by adjusting the network parameters in real time. In the Webots enviroment,a professional mobile robot simulation software,the design of a bio-inspired hexapod robot is developed and the controller programming is performed. and the kinematic simulation experiments for the robot are conducted with Webots. The experimental results show that the robot has a reasonable mechanism and the control method is feasible and the crawling speed of approximately 2. 7 cm /sec can be achieved.
The adhesive between robot's feet and walls,and the control strategy are two key elements in wallclimbing robots. Inspired by the beetle claws and inchworm-like motion,a flexible steerable beetle-inspired hexapod climbing robot is designed in this paper. The bionic control method,i. e. Central Pattern Generator(CPG) is used to achieve straight motion and obstacle avoidance ability. The robot foot with crawling grasping is designed to improve its climbing stability. The structure of robot is simple,and the CGP control method is simple and innovative. Based on MATLAB software,the CPG control network is constructed combined with ultrasonic sensor feedback signal. The correct control signals can be obtained by adjusting the network parameters in real time. In the Webots enviroment,a professional mobile robot simulation software,the design of a bio-inspired hexapod robot is developed and the controller programming is performed. and the kinematic simulation experiments for the robot are conducted with Webots. The experimental results show that the robot has a reasonable mechanism and the control method is feasible and the crawling speed of approximately 2. 7 cm /sec can be achieved.
2014, 33(11): 1627-1632.
doi: 10.13433/j.cnki.1003-8728.2014.1104
Abstract:
To investigate the shape characteristic and the user emotion in the product shape design process,a semantic-based adaptive hybrid immune genetic design approach is proposed. The initial antibody set was generated as a result of matching with the target design fussy definition. Then the extracted vaccine set was created based on the experts'feedback and evaluation. During the evolution process,the antibodies convergence was accelerated and the diversity was maintained by the vaccination and affinity-based selection. Also,the fitness function was defined with a back-propagation neural network which maps the semantic space of the shape characteristic design to the semantic space of the emotion. In addition,the vaccination possibilities of vaccines adapt to the effects of vaccination and the affinities and selection possibilities of antibodies were defined according to the information entropy theory. The results of prototype system demonstrated that the present method can efficiently generate and evaluate product shape design scheme.
To investigate the shape characteristic and the user emotion in the product shape design process,a semantic-based adaptive hybrid immune genetic design approach is proposed. The initial antibody set was generated as a result of matching with the target design fussy definition. Then the extracted vaccine set was created based on the experts'feedback and evaluation. During the evolution process,the antibodies convergence was accelerated and the diversity was maintained by the vaccination and affinity-based selection. Also,the fitness function was defined with a back-propagation neural network which maps the semantic space of the shape characteristic design to the semantic space of the emotion. In addition,the vaccination possibilities of vaccines adapt to the effects of vaccination and the affinities and selection possibilities of antibodies were defined according to the information entropy theory. The results of prototype system demonstrated that the present method can efficiently generate and evaluate product shape design scheme.
2014, 33(11): 1633-1636.
doi: 10.13433/j.cnki.1003-8728.2014.1105
Abstract:
The single freedom degree mechanisms have a feature with single-input and multi-output. In traditional mechanisms reliability,the analysis model for kinematic reliability is created with each coordinate direction component. The present model can not embody the overall failure conditions of mechanisms. Finally,the motion error model and the analysis model for kinematic reliability are presented based on the circular area. The first order reliability method(FORM) is used to solve the present model. To improve the calculation accuracy,a hybrid optimization algorithm which includes genetic algorithm(GA) and sequential quadratic programming(SQP)algorithm is presented to find the most probable point. A numerical example is given to demonstrate the effectiveness of the present method.
The single freedom degree mechanisms have a feature with single-input and multi-output. In traditional mechanisms reliability,the analysis model for kinematic reliability is created with each coordinate direction component. The present model can not embody the overall failure conditions of mechanisms. Finally,the motion error model and the analysis model for kinematic reliability are presented based on the circular area. The first order reliability method(FORM) is used to solve the present model. To improve the calculation accuracy,a hybrid optimization algorithm which includes genetic algorithm(GA) and sequential quadratic programming(SQP)algorithm is presented to find the most probable point. A numerical example is given to demonstrate the effectiveness of the present method.
2014, 33(11): 1637-1642.
doi: 10.13433/j.cnki.1003-8728.2014.1106
Abstract:
In order to study the vibration control strategy of Adaptive-Tuned-Mass-Damper(ATMD),the control effect of the absorber mass and the coupling damp of the ATMD is analyzed,and the equations of motion for different mathematical models are built. The control effectiveness with and without considering static and dynamic mass is analyzed and compared. Then the control strategy for the ATMD is studied. To match the natural frequency of ATMD to the excitation frequency,the relative phase between the main system and the subsystem at the tuned condition is chosen as the evaluate index,the mass of subsystem and the excitation frequency are fitted to achieve the control equation,an open-loop mass-dynamic-matching control method is proposed,the control mass in different exciting frequencies can be obtained by tracking the control equation then the vibration amplitude of the main system and be reduced in a broad frequency range. Experimental result shows that the proposed method can exhibit fast and stable control on the system and it also provide theoretical reference for further study on the closed-loop control strategy.
In order to study the vibration control strategy of Adaptive-Tuned-Mass-Damper(ATMD),the control effect of the absorber mass and the coupling damp of the ATMD is analyzed,and the equations of motion for different mathematical models are built. The control effectiveness with and without considering static and dynamic mass is analyzed and compared. Then the control strategy for the ATMD is studied. To match the natural frequency of ATMD to the excitation frequency,the relative phase between the main system and the subsystem at the tuned condition is chosen as the evaluate index,the mass of subsystem and the excitation frequency are fitted to achieve the control equation,an open-loop mass-dynamic-matching control method is proposed,the control mass in different exciting frequencies can be obtained by tracking the control equation then the vibration amplitude of the main system and be reduced in a broad frequency range. Experimental result shows that the proposed method can exhibit fast and stable control on the system and it also provide theoretical reference for further study on the closed-loop control strategy.
2014, 33(11): 1643-1647.
doi: 10.13433/j.cnki.1003-8728.2014.1107
Abstract:
In computer vision,there is a problem that the target recognition method only based on color feature can't filter the interference objects which have the same color with target object. A new target recognition method based on both object's colour and size features has been presented in this paper. In order to achieve the goal of object recognition,by combining the HSV colour space conversion,the threshold method and seed growth method have been used to implement image colour featrue extraction,and under the support of binocular vision technology,the size feature has been used to filter those image regions which have been extracted by image segmentation. The method has been proved by experiments to be effective in the regular shape object recognition.
In computer vision,there is a problem that the target recognition method only based on color feature can't filter the interference objects which have the same color with target object. A new target recognition method based on both object's colour and size features has been presented in this paper. In order to achieve the goal of object recognition,by combining the HSV colour space conversion,the threshold method and seed growth method have been used to implement image colour featrue extraction,and under the support of binocular vision technology,the size feature has been used to filter those image regions which have been extracted by image segmentation. The method has been proved by experiments to be effective in the regular shape object recognition.
2014, 33(11): 1648-1651.
doi: 10.13433/j.cnki.1003-8728.2014.1108
Abstract:
In order to research kinematics of the new lifting mechanisms with movable back-hinged-bearing,the mechanical,hydraulic and controll models are built with Pro /Engineer,ADAMS,AMESim and Simulink softwares,and jointed simulations are realized and the principle of fuzzy PID control is analyzed. The lifting process is divided into subsections and the trajectories of the lifting angle and displacement of horizontal cylinder are planned. The simulation results demonstrate that the design of the new lifting mechanisms is reasonable and it can achieve the anticipated motion trajectories; the technology of jointed simulation does not need the deduction of mathematical model and it can play the advantage of each software with high modeling efficiency. The fuzzy PID control technique enhances the anti-jamming ability and the stability of the system. The displacement,velocity,acceleration curves of four-five-six-seven polynomial interpolation and the impact curves are smooth without abrupt turns.
In order to research kinematics of the new lifting mechanisms with movable back-hinged-bearing,the mechanical,hydraulic and controll models are built with Pro /Engineer,ADAMS,AMESim and Simulink softwares,and jointed simulations are realized and the principle of fuzzy PID control is analyzed. The lifting process is divided into subsections and the trajectories of the lifting angle and displacement of horizontal cylinder are planned. The simulation results demonstrate that the design of the new lifting mechanisms is reasonable and it can achieve the anticipated motion trajectories; the technology of jointed simulation does not need the deduction of mathematical model and it can play the advantage of each software with high modeling efficiency. The fuzzy PID control technique enhances the anti-jamming ability and the stability of the system. The displacement,velocity,acceleration curves of four-five-six-seven polynomial interpolation and the impact curves are smooth without abrupt turns.
2014, 33(11): 1652-1655.
doi: 10.13433/j.cnki.1003-8728.2014.1109
Abstract:
To improve the lubrication performance in radial clearance of gear addendum in external gear pumps,the eccentric design method of gear pairs relative to the center of pump case was put forward to strengthen dynamic pressure lubrication effect in the radial clearance. Based on comprehensive consideration of the relative factors such as pump case deformation and the decentraction of shaft and bearing,under the combination effect of differential pressure and dynamic pressure in the radial clearance,the leakage rate through the radial clearance from discharge side of pump to suction side was calculated; and from the minimized condition of the leakage rate,the eccentric distance of gear pairs relative to the center of pump case was derived. All results showed that the higher the rotating speed was,the smaller the eccentric distance was,then the smaller the leakage rate was,so the more obvious the increased volumetric efficiency of pump was; the greater the discharge pressure was,the bigger the eccentric distance was,so the bigger the leakage rate was,then the less obvious the increased volumetric efficiency was,and so on. Finally,the important conclusion is drawn that the dynamic lubrication effect improvement obtained by the eccentric distance is more obvious.
To improve the lubrication performance in radial clearance of gear addendum in external gear pumps,the eccentric design method of gear pairs relative to the center of pump case was put forward to strengthen dynamic pressure lubrication effect in the radial clearance. Based on comprehensive consideration of the relative factors such as pump case deformation and the decentraction of shaft and bearing,under the combination effect of differential pressure and dynamic pressure in the radial clearance,the leakage rate through the radial clearance from discharge side of pump to suction side was calculated; and from the minimized condition of the leakage rate,the eccentric distance of gear pairs relative to the center of pump case was derived. All results showed that the higher the rotating speed was,the smaller the eccentric distance was,then the smaller the leakage rate was,so the more obvious the increased volumetric efficiency of pump was; the greater the discharge pressure was,the bigger the eccentric distance was,so the bigger the leakage rate was,then the less obvious the increased volumetric efficiency was,and so on. Finally,the important conclusion is drawn that the dynamic lubrication effect improvement obtained by the eccentric distance is more obvious.
2014, 33(11): 1656-1660.
doi: 10.13433/j.cnki.1003-8728.2014.1110
Abstract:
Using the fractal characteristics of crush after the quality of the material particle size distribution under different rotation speed for new vertical grinding mill,the fractal model for crushing experiments was established.To analyze the experimental data,the regression forecasting model for the crushing fractal dimension was established based on the relationship between the crushing fractal dimension and the vertical grinding mill rotation speed,broken rate. Considering the rotating speed and broken rate for vertical grinding mill,the optimized parameters provide a reference for the optimal design of vertical grinding mill.
Using the fractal characteristics of crush after the quality of the material particle size distribution under different rotation speed for new vertical grinding mill,the fractal model for crushing experiments was established.To analyze the experimental data,the regression forecasting model for the crushing fractal dimension was established based on the relationship between the crushing fractal dimension and the vertical grinding mill rotation speed,broken rate. Considering the rotating speed and broken rate for vertical grinding mill,the optimized parameters provide a reference for the optimal design of vertical grinding mill.
2014, 33(11): 1661-1664.
doi: 10.13433/j.cnki.1003-8728.2014.1111
Abstract:
Basing on the study of type I and type II contact lines of worm pairs,the special contact lines on the meshing surface with transmission point have been explored and analyzed by using the theory of spatial engagement.Firstly,the meshing equation and contact line equation have been analyzed and deduced,so the equation and coordinates of transmission point has been achieved. Next,the transmission point on the contact line of enveloping worm pairs is analyzed,and the types of contact lines on the mesh surface are discerned,the effect of the type of contact line on the property of worm pairs is analyzed. Furthermore the ralationship between the transmission point of contact line and symmetrical shape optimization parameters is also studied. The results provide reference data to the shape optimization for worm gears and supply parameters for the field assembling of worm pairs.
Basing on the study of type I and type II contact lines of worm pairs,the special contact lines on the meshing surface with transmission point have been explored and analyzed by using the theory of spatial engagement.Firstly,the meshing equation and contact line equation have been analyzed and deduced,so the equation and coordinates of transmission point has been achieved. Next,the transmission point on the contact line of enveloping worm pairs is analyzed,and the types of contact lines on the mesh surface are discerned,the effect of the type of contact line on the property of worm pairs is analyzed. Furthermore the ralationship between the transmission point of contact line and symmetrical shape optimization parameters is also studied. The results provide reference data to the shape optimization for worm gears and supply parameters for the field assembling of worm pairs.
2014, 33(11): 1665-1671.
doi: 10.13433/j.cnki.1003-8728.2014.1112
Abstract:
Having the concentrator of 25 kW dish photo-thermal solar system as the research object. This paper establishes the finite element model,programms Matlab programs based on superposition of harmonic theory to obtain the fluctuating wind load time-history research about wind-induced vibration response of concentrator. The statistical characteristics and wind vibration coefficient of displacement at key nodes are obtained; the response time-history data and the power spectrum analysis are carried out for some nodes. Results show that concentrator structure happened mainly forced vibration of low frequency parts and slight resonance on the fundamental frequency in extreme wind load;the most unfavorable condition is 90�60�the safe sheltered condition is-90�90�the wind vibration coefficient of overall displacement is 2. 4 in the most unfavorable condition; concentrator structure is in elastic deformation stage under extreme wind load,but solid mirror shell vibrates strongly; finally the security of the mirror remains to be further studied.
Having the concentrator of 25 kW dish photo-thermal solar system as the research object. This paper establishes the finite element model,programms Matlab programs based on superposition of harmonic theory to obtain the fluctuating wind load time-history research about wind-induced vibration response of concentrator. The statistical characteristics and wind vibration coefficient of displacement at key nodes are obtained; the response time-history data and the power spectrum analysis are carried out for some nodes. Results show that concentrator structure happened mainly forced vibration of low frequency parts and slight resonance on the fundamental frequency in extreme wind load;the most unfavorable condition is 90�60�the safe sheltered condition is-90�90�the wind vibration coefficient of overall displacement is 2. 4 in the most unfavorable condition; concentrator structure is in elastic deformation stage under extreme wind load,but solid mirror shell vibrates strongly; finally the security of the mirror remains to be further studied.
2014, 33(11): 1672-1676.
doi: 10.13433/j.cnki.1003-8728.2014.1113
Abstract:
The identification of multiple loads on the beam from the dynamical responses was investigated. Firstly,the measured responses of the beam on different positions were mapped into phase space and decomposed by Singular Value Decomposition(SVD). Then the obtained signal vector's elements were rearranged by the energy levels corresponding to different eigenvalues. Based on the present results,the load's number was determined.Furthermore,according to the natural correlations of the signals'time-frequency relation corresponding to the same load,the responses'amplitudes were determined. Finally,based on the mode space and optimization,the identification method for the concentrated loads on beam was presented and proved theoretically. The calculation was carried in the case of harmonic and time-varied load,and the results showed that the presented method was correct and had high accuracy.
The identification of multiple loads on the beam from the dynamical responses was investigated. Firstly,the measured responses of the beam on different positions were mapped into phase space and decomposed by Singular Value Decomposition(SVD). Then the obtained signal vector's elements were rearranged by the energy levels corresponding to different eigenvalues. Based on the present results,the load's number was determined.Furthermore,according to the natural correlations of the signals'time-frequency relation corresponding to the same load,the responses'amplitudes were determined. Finally,based on the mode space and optimization,the identification method for the concentrated loads on beam was presented and proved theoretically. The calculation was carried in the case of harmonic and time-varied load,and the results showed that the presented method was correct and had high accuracy.
2014, 33(11): 1677-1681.
doi: 10.13433/j.cnki.1003-8728.2014.1114
Abstract:
To solve the problem of the force /position coupling on aspheric surface polishing process,a kind of model was built to improve the polishing precision using the magnetorheological fluid torque servo control device to control the force,when the position and speed were controlled by the numerical lathe. According to the Preston polishing control principle, a force control implementation model was established. Based on the polishing parameter,the polishing experiment was done. By calculating the swell time of the ellipsoid surface polishing,the relation of the polishing time and polishing force was built. Through controlling the output of current of magnetorheological liquid servo device to get the corresponding polishing control force to match the position and speed given by NC machine tool. The experimental results show that the proposed force /position control method can achieve high precision polishing.
To solve the problem of the force /position coupling on aspheric surface polishing process,a kind of model was built to improve the polishing precision using the magnetorheological fluid torque servo control device to control the force,when the position and speed were controlled by the numerical lathe. According to the Preston polishing control principle, a force control implementation model was established. Based on the polishing parameter,the polishing experiment was done. By calculating the swell time of the ellipsoid surface polishing,the relation of the polishing time and polishing force was built. Through controlling the output of current of magnetorheological liquid servo device to get the corresponding polishing control force to match the position and speed given by NC machine tool. The experimental results show that the proposed force /position control method can achieve high precision polishing.
2014, 33(11): 1682-1687.
doi: 10.13433/j.cnki.1003-8728.2014.1115
Abstract:
In view of the strong background noise involved in the fault signal of tool wears and the difficulty to obtain fault feature frequencies, in this paper, a fault feature extraction method was proposed based on morphological filters and combining with empirical mode decomposition. At the same time,tool wears were identified by genetic algorithm(GA)-fuzzy-neural networks with B-spline membership functions. Fuzzy neural networks are traditionally trained by using gradient-based methods,and may fall into local minimum during the learning process. So,the genetic algorithm was adopted for global optimization in this study. The experimental results show that the diagnosis approach put forward in this paper can effectively identify tool wears in strong background noise.
In view of the strong background noise involved in the fault signal of tool wears and the difficulty to obtain fault feature frequencies, in this paper, a fault feature extraction method was proposed based on morphological filters and combining with empirical mode decomposition. At the same time,tool wears were identified by genetic algorithm(GA)-fuzzy-neural networks with B-spline membership functions. Fuzzy neural networks are traditionally trained by using gradient-based methods,and may fall into local minimum during the learning process. So,the genetic algorithm was adopted for global optimization in this study. The experimental results show that the diagnosis approach put forward in this paper can effectively identify tool wears in strong background noise.
2014, 33(11): 1688-1693.
doi: 10.13433/j.cnki.1003-8728.2014.1116
Abstract:
The factors affect the printing accuracy for powdery materials is analyzed in three dimensional printing(3DP) process,the experiment is used to determine the range of shrinkage of the printing process for the threedimensional components. The "H" type component as the test specimen,the neural network(NN) is used to describe the complicated relationship between the dimensional accuracy of component and printing processing parameters. As the goal of the minimum dimensional accuracy of specimen,the genetic algorithm(GA) is used to optimize the 3DP printing parameters such as saturation,the layer thickness and compensation in three directions X,Y and Z respectively. The comparing experiments for 3DP using default parameters of printer,the minimum and maximum value in the range of printing parameters,and the NN-GA obtained parameters are conducted,and the results show that the dimensional accuracy is the best using the printing processing parameters of the NN-GA obtained,which show that the NN-GA can predict the dimensional accuracy for 3DP printing processing and provide the reference for other similar fabrication method.
The factors affect the printing accuracy for powdery materials is analyzed in three dimensional printing(3DP) process,the experiment is used to determine the range of shrinkage of the printing process for the threedimensional components. The "H" type component as the test specimen,the neural network(NN) is used to describe the complicated relationship between the dimensional accuracy of component and printing processing parameters. As the goal of the minimum dimensional accuracy of specimen,the genetic algorithm(GA) is used to optimize the 3DP printing parameters such as saturation,the layer thickness and compensation in three directions X,Y and Z respectively. The comparing experiments for 3DP using default parameters of printer,the minimum and maximum value in the range of printing parameters,and the NN-GA obtained parameters are conducted,and the results show that the dimensional accuracy is the best using the printing processing parameters of the NN-GA obtained,which show that the NN-GA can predict the dimensional accuracy for 3DP printing processing and provide the reference for other similar fabrication method.
2014, 33(11): 1694-1699.
doi: 10.13433/j.cnki.1003-8728.2014.1117
Abstract:
Firstly,the essential differences between the hybrid ceramic ball bearing motorized spindle and steel ball bearing motorized spindle are analyzed. Then,the performance degradation reliability testing scheme of motorized spindle is designed. And the reliability tests of motorized spindle are performed under the guidance of the scheme.The reliability evaluation accuracy is low whether the false life distribution method or Bayes method is used. For this problem,the method of reliability assessment based on the method of false-life distribution combined with Bayes method is presented. And the reliability testing data of two types of motorized spindle samples are analyzed by this method,respectively. The reliability evaluation results of the motorized spindle are obtained. At the same time,the reliability indexes of the two types of motorized spindles are compared and analyzed. So,their advantages and disadvantages in reliability are achieved.
Firstly,the essential differences between the hybrid ceramic ball bearing motorized spindle and steel ball bearing motorized spindle are analyzed. Then,the performance degradation reliability testing scheme of motorized spindle is designed. And the reliability tests of motorized spindle are performed under the guidance of the scheme.The reliability evaluation accuracy is low whether the false life distribution method or Bayes method is used. For this problem,the method of reliability assessment based on the method of false-life distribution combined with Bayes method is presented. And the reliability testing data of two types of motorized spindle samples are analyzed by this method,respectively. The reliability evaluation results of the motorized spindle are obtained. At the same time,the reliability indexes of the two types of motorized spindles are compared and analyzed. So,their advantages and disadvantages in reliability are achieved.
2014, 33(11): 1700-1704.
doi: 10.13433/j.cnki.1003-8728.2014.1118
Abstract:
Lasers and tapes are mostly applied in indoor three dimensional measurements for the moment,which have weaknesses such as many human factors,low efficiency and large difficulty to measure irregular rooms. To solve the problems in the 3D measurement of indoor buildings,a new three dimensional automatic measurement algorithm as well as the related mechanical and control systems were developed. The path planning of the threedimensional machine is introduced,the process of building up several plane coordinates and sampling the data is illustrated,to acquire the accurate data of the 3D is rapidly analyzed by using coordinate transition and fitting a straight line by the least square method and the space analytic geometry. The rapid automated high accurate measurement is achieved by measuring sample building.
Lasers and tapes are mostly applied in indoor three dimensional measurements for the moment,which have weaknesses such as many human factors,low efficiency and large difficulty to measure irregular rooms. To solve the problems in the 3D measurement of indoor buildings,a new three dimensional automatic measurement algorithm as well as the related mechanical and control systems were developed. The path planning of the threedimensional machine is introduced,the process of building up several plane coordinates and sampling the data is illustrated,to acquire the accurate data of the 3D is rapidly analyzed by using coordinate transition and fitting a straight line by the least square method and the space analytic geometry. The rapid automated high accurate measurement is achieved by measuring sample building.
2014, 33(11): 1705-1707.
doi: 10.13433/j.cnki.1003-8728.2014.1119
Abstract:
Through the different forms of simultaneous characteristic equations of the solid-liquid two-phase flow pump volute,a new mathematical relationship between the new two-phase flow pump flow lift and the basic circle,the throat area of volute,etc. is obtained,and then the influence of the volute structure(basic circle,mouthpiece area) on the lift of two phase flow pump is analyzed. The results show that the lift of two phase flow pump is proportional to the basic circle diameter of volute,and is inversely proportional to the throat area of volute.
Through the different forms of simultaneous characteristic equations of the solid-liquid two-phase flow pump volute,a new mathematical relationship between the new two-phase flow pump flow lift and the basic circle,the throat area of volute,etc. is obtained,and then the influence of the volute structure(basic circle,mouthpiece area) on the lift of two phase flow pump is analyzed. The results show that the lift of two phase flow pump is proportional to the basic circle diameter of volute,and is inversely proportional to the throat area of volute.
2014, 33(11): 1708-1713.
doi: 10.13433/j.cnki.1003-8728.2014.1120
Abstract:
A novel adaptive fuzzy controller applied to the semi-active suspension with magnetorhelogical damper is introduced in this paper,which combines neural networks with fuzzy control and complements training fuzzy control rules and membership function with neural network. In order to comprehensively reflect the performance of car's roll and pitch,the nonlinear dynamical model of semi-active suspension with seven degrees of freedom and the random road model of four wheels are established,using an improved Bouc-Wen model of magnetorhelogical damper.Meanwhile,in order to verify the stability of the controller,the brake model and the steering model are added,which may really reflect traveling road condition of the car. The simulation results show that: the neuro-fuzzy controller can decrease dynamic displacement of each suspension,the body's vertical acceleration,roll angular acceleration and pitch angular acceleration,and raise the comfort and safety of the car,and its improving magnitude is better than the semi-active suspension with the fractional PID controller optimized by atavistic algorithm.
A novel adaptive fuzzy controller applied to the semi-active suspension with magnetorhelogical damper is introduced in this paper,which combines neural networks with fuzzy control and complements training fuzzy control rules and membership function with neural network. In order to comprehensively reflect the performance of car's roll and pitch,the nonlinear dynamical model of semi-active suspension with seven degrees of freedom and the random road model of four wheels are established,using an improved Bouc-Wen model of magnetorhelogical damper.Meanwhile,in order to verify the stability of the controller,the brake model and the steering model are added,which may really reflect traveling road condition of the car. The simulation results show that: the neuro-fuzzy controller can decrease dynamic displacement of each suspension,the body's vertical acceleration,roll angular acceleration and pitch angular acceleration,and raise the comfort and safety of the car,and its improving magnitude is better than the semi-active suspension with the fractional PID controller optimized by atavistic algorithm.
2014, 33(11): 1714-1718.
doi: 10.13433/j.cnki.1003-8728.2014.1121
Abstract:
A method of oil film dynamic compensation technology for gasoline engine in the acceleration transient condition was studied in order to improve the Air-Fuel Ratio(AFR) control accuracy and meet the requirements of gasoline engine power,economy and emission properties. The parameters of oil film were identified by using the Elman neural networks; an oil film compensator model for gasoline engine in the acceleration transient condition was established by simulation software. Based on MotoTron rapid prototyping development platform,the oil film compensator model was transplanted,downloaded,calibrated,and verified by simulation and experiment. The results show that the Elman neural network can identify the parameters of oil film of gasoline engine,and can eliminate the oil film dynamic effect on the AFR; the oil film compensator can compensate effectively for injection of gasoline engine; and AFR can be controlled effectively in the acceleration transient conditions.
A method of oil film dynamic compensation technology for gasoline engine in the acceleration transient condition was studied in order to improve the Air-Fuel Ratio(AFR) control accuracy and meet the requirements of gasoline engine power,economy and emission properties. The parameters of oil film were identified by using the Elman neural networks; an oil film compensator model for gasoline engine in the acceleration transient condition was established by simulation software. Based on MotoTron rapid prototyping development platform,the oil film compensator model was transplanted,downloaded,calibrated,and verified by simulation and experiment. The results show that the Elman neural network can identify the parameters of oil film of gasoline engine,and can eliminate the oil film dynamic effect on the AFR; the oil film compensator can compensate effectively for injection of gasoline engine; and AFR can be controlled effectively in the acceleration transient conditions.
2014, 33(11): 1719-1724.
doi: 10.13433/j.cnki.1003-8728.2014.1122
Abstract:
Aiming at the shortages of low efficiency and large fuel consumption of traditional truck-mounted concrete pump,the fuel consumption of its engine are tested and modeled. The specific fuel consumption of the engine is bench tested under different velocity and torque. The experimental data are curved-fitted and revised based on the traditional universal characteristic curve. Through the multi-dimension curve map,the useful specific fuel consumption model is obtained. The full throttle curve is redefined at the same time. The results show that the engine will run in a high efficiency within medium and high velocity and torque. It is better for the engine to work on the high efficiency region if it can satisfy the load requirement of the truck,the fuel economy of the vehicle can be highly improved. The results of fuel consumption tests for the truck-mounted concrete pump verify the economic and high efficiency running range,and the operation efficiency of the concrete pump is improved.
Aiming at the shortages of low efficiency and large fuel consumption of traditional truck-mounted concrete pump,the fuel consumption of its engine are tested and modeled. The specific fuel consumption of the engine is bench tested under different velocity and torque. The experimental data are curved-fitted and revised based on the traditional universal characteristic curve. Through the multi-dimension curve map,the useful specific fuel consumption model is obtained. The full throttle curve is redefined at the same time. The results show that the engine will run in a high efficiency within medium and high velocity and torque. It is better for the engine to work on the high efficiency region if it can satisfy the load requirement of the truck,the fuel economy of the vehicle can be highly improved. The results of fuel consumption tests for the truck-mounted concrete pump verify the economic and high efficiency running range,and the operation efficiency of the concrete pump is improved.
2014, 33(11): 1725-1728.
doi: 10.13433/j.cnki.1003-8728.2014.1123
Abstract:
The subjective estimation indicators for the drivability of vehicle equipped with CVT's include ride comfort,shock and vibration properties and response of acceleration pedal,etc. Analytic hierarchy process is applied to evaluate these parameters. Firstly,the corresponding evaluation model is established,and the importance of scale is improved. Then the results of the evaluation are analyzed. By analyzing the evaluation results of conventional driving,the subjective estimation of drivability for vehicle equipped with CVT's can be scientifically quantified.
The subjective estimation indicators for the drivability of vehicle equipped with CVT's include ride comfort,shock and vibration properties and response of acceleration pedal,etc. Analytic hierarchy process is applied to evaluate these parameters. Firstly,the corresponding evaluation model is established,and the importance of scale is improved. Then the results of the evaluation are analyzed. By analyzing the evaluation results of conventional driving,the subjective estimation of drivability for vehicle equipped with CVT's can be scientifically quantified.
2014, 33(11): 1729-1732.
doi: 10.13433/j.cnki.1003-8728.2014.1124
Abstract:
In order to surmount the obstacles in rough terrain,a new type of wheel-leg hybrid wheel was designed in this paper. Firstly,the working principle of the wheel was introduced. Secondly,the 3D CAD model for the miniature wheel-and-leg hybrid wheel was designed via SolidWorks software. Lastly,the static mechanics analysis via ANSYS software was made and then the wheel-and-leg hybrid wheel was improved based on the analysis results.The analysis results via ANSYS software were compared between the original and the optimized wheel. The conclusion can be made that both the weight and the moment of inertia were lessened,additionally the mechanics requirement was met to surmount the obstacles by the improved design.
In order to surmount the obstacles in rough terrain,a new type of wheel-leg hybrid wheel was designed in this paper. Firstly,the working principle of the wheel was introduced. Secondly,the 3D CAD model for the miniature wheel-and-leg hybrid wheel was designed via SolidWorks software. Lastly,the static mechanics analysis via ANSYS software was made and then the wheel-and-leg hybrid wheel was improved based on the analysis results.The analysis results via ANSYS software were compared between the original and the optimized wheel. The conclusion can be made that both the weight and the moment of inertia were lessened,additionally the mechanics requirement was met to surmount the obstacles by the improved design.
2014, 33(11): 1733-1738.
doi: 10.13433/j.cnki.1003-8728.2014.1125
Abstract:
The finite element model of TY dump truck frame was established in Hypermesh. Analysis for strength and stiffness of the frame was done under bending and torsion conditions,and the accuracy of the finite element model was verified by modal tests. Through analyzing flexibility sensitivity,modal sensitivity and quality sensitivity for frame parameters,the optimal design variables were determined based on the results of the relative sensitivity analysis. The lightweight optimization design was applied in the frame structure under the condition of meeting the stiffness and low order modal frequencies. The results show that the strength,stiffness and low order modal frequencies of the optimized frame are increased,the stress concentration is avoided,and the frame weight is reduced by 70 kg,which illustrate the validity of the lightweight design method.
The finite element model of TY dump truck frame was established in Hypermesh. Analysis for strength and stiffness of the frame was done under bending and torsion conditions,and the accuracy of the finite element model was verified by modal tests. Through analyzing flexibility sensitivity,modal sensitivity and quality sensitivity for frame parameters,the optimal design variables were determined based on the results of the relative sensitivity analysis. The lightweight optimization design was applied in the frame structure under the condition of meeting the stiffness and low order modal frequencies. The results show that the strength,stiffness and low order modal frequencies of the optimized frame are increased,the stress concentration is avoided,and the frame weight is reduced by 70 kg,which illustrate the validity of the lightweight design method.
2014, 33(11): 1739-1743.
doi: 10.13433/j.cnki.1003-8728.2014.1126
Abstract:
The current spring-back variation model for spot welding of auto body flexible sheet,in which the points contact at the edge of sheet does not consider the lap width set in the spot welding production,therefore it does not apply to the analysis of assembly quality. In this paper,a cantilever structure with surface contacting is firstly established by analyzing the locating and assembly process of the flexible sheet and the spot welding process. Then,a model for the spring-back variation of lap welding joint considering lap width is presented based on the analysis of welding joint force. The sensitivity of parameters is verified by comparing the traditional spring-back variation model without lap width. Finally,a case of rectangular sheet metal assembly was used to reveal the effectiveness of the assembly variation model.
The current spring-back variation model for spot welding of auto body flexible sheet,in which the points contact at the edge of sheet does not consider the lap width set in the spot welding production,therefore it does not apply to the analysis of assembly quality. In this paper,a cantilever structure with surface contacting is firstly established by analyzing the locating and assembly process of the flexible sheet and the spot welding process. Then,a model for the spring-back variation of lap welding joint considering lap width is presented based on the analysis of welding joint force. The sensitivity of parameters is verified by comparing the traditional spring-back variation model without lap width. Finally,a case of rectangular sheet metal assembly was used to reveal the effectiveness of the assembly variation model.
2014, 33(11): 1744-1747.
doi: 10.13433/j.cnki.1003-8728.2014.1127
Abstract:
In order to discover the relationship between the transverse equivalent modulus of elasticity and parameters(porosity,hole shape,hole arrays) of metal perforated foil,the mechanical properties of the unit cell of metal perforated foil is studied by using finite element analysis software ANSYS according to homogenization theory in this paper. The results show the transverse equivalent modulus of elasticity for metal perforated foil is mainly determined by porosity,the larger the porosity,the less the transverse equivalent modulus of elasticity; Hole shape and hole arrays have some influence on the transverse equivalent modulus of elasticity,the influence is more obvious with the increasing of porosity. Reducing the transverse area of hole is beneficial to increase the transverse equivalent modulus of elasticity. Finally,the numerical results are verified by experiments,the results show that some errors exist in FEM simulation results.
In order to discover the relationship between the transverse equivalent modulus of elasticity and parameters(porosity,hole shape,hole arrays) of metal perforated foil,the mechanical properties of the unit cell of metal perforated foil is studied by using finite element analysis software ANSYS according to homogenization theory in this paper. The results show the transverse equivalent modulus of elasticity for metal perforated foil is mainly determined by porosity,the larger the porosity,the less the transverse equivalent modulus of elasticity; Hole shape and hole arrays have some influence on the transverse equivalent modulus of elasticity,the influence is more obvious with the increasing of porosity. Reducing the transverse area of hole is beneficial to increase the transverse equivalent modulus of elasticity. Finally,the numerical results are verified by experiments,the results show that some errors exist in FEM simulation results.
2014, 33(11): 1748-1752.
doi: 10.13433/j.cnki.1003-8728.2014.1128
Abstract:
This paper describes the single streamtube, multiple streamtube and double-multiple streamtube aerodynamic performance prediction models based on blade-element momentum theory for modeling the straightblade vertical axis wind turbine. An improved double-multiple streamtube model considering the tangential induced factor is developed according to the technical route used in horizontal axis wind turbine. Comparisons of the analytical results with the available experimental data from Sandia reports and other relative simulations show a good agreement,which proves the availability and practicability of the modeling method improved in this work.
This paper describes the single streamtube, multiple streamtube and double-multiple streamtube aerodynamic performance prediction models based on blade-element momentum theory for modeling the straightblade vertical axis wind turbine. An improved double-multiple streamtube model considering the tangential induced factor is developed according to the technical route used in horizontal axis wind turbine. Comparisons of the analytical results with the available experimental data from Sandia reports and other relative simulations show a good agreement,which proves the availability and practicability of the modeling method improved in this work.
2014, 33(11): 1753-1757.
doi: 10.13433/j.cnki.1003-8728.2014.1129
Abstract:
In order to explore the application of topology optimization to the design of landing gear structure,the topology optimization model of an UAV landing gear outer cylinder is created based on the variable density method.Under the help of the well-known structure optimization platform OptiStruct,the optimal topology structure is obtained,which can meet the requirements of a variety of constraints and typical loading cases. The finite element simulation results show that it not only reduces the weight by 20% but also reduces the stress level greatly,and the design requirements of strength and stiffness are met. The topology optimization design method is of great significance for improving the landing gear structure design,realizing the lightweight design and enhancing the aircraft performance.
In order to explore the application of topology optimization to the design of landing gear structure,the topology optimization model of an UAV landing gear outer cylinder is created based on the variable density method.Under the help of the well-known structure optimization platform OptiStruct,the optimal topology structure is obtained,which can meet the requirements of a variety of constraints and typical loading cases. The finite element simulation results show that it not only reduces the weight by 20% but also reduces the stress level greatly,and the design requirements of strength and stiffness are met. The topology optimization design method is of great significance for improving the landing gear structure design,realizing the lightweight design and enhancing the aircraft performance.
2014, 33(11): 1758-1762.
doi: 10.13433/j.cnki.1003-8728.2014.1130
Abstract:
Using the Markov reliability analysis approach,the reliability modeling and assement for the rudder system of a civil airplane is presented. Based on the selection of rudder system key LRU(line replaceable unit),the main fault modes for the corresponding key equipment are classified and analyzed,and then the Markov reliability model is developed to assess the mean time to failure(MTTF) of the rudder system. Moreover,the rudder actuator system architecture assement and other reliability factor analysis are conducted during this process.The modeling and assement process is simple and practical,and it can not only help the reliability assessment and fault tolerance designof rudder system,but also can be extended to the application of to other system.
Using the Markov reliability analysis approach,the reliability modeling and assement for the rudder system of a civil airplane is presented. Based on the selection of rudder system key LRU(line replaceable unit),the main fault modes for the corresponding key equipment are classified and analyzed,and then the Markov reliability model is developed to assess the mean time to failure(MTTF) of the rudder system. Moreover,the rudder actuator system architecture assement and other reliability factor analysis are conducted during this process.The modeling and assement process is simple and practical,and it can not only help the reliability assessment and fault tolerance designof rudder system,but also can be extended to the application of to other system.
2014, 33(11): 1763-1767.
doi: 10.13433/j.cnki.1003-8728.2014.1131
Abstract:
Based on the clarification of vertical lifting type landing gear retraction principle,a design method which complies the vertical lifting landing gear retraction mechanism is given. Lifting mechanism selection,structural design and parameters determination of its main component-the ball screw vice's are the main considerations in this study. In order to ensure the rational of the design of the vertical lifting landing gear retraction mechanism,two main failure modes-static load failure and dynamic load failure of the main component of the lifting mechanism-the ball screw vice are analyzed and the reliability analysis model is established,then the reliability index is calculated.
Based on the clarification of vertical lifting type landing gear retraction principle,a design method which complies the vertical lifting landing gear retraction mechanism is given. Lifting mechanism selection,structural design and parameters determination of its main component-the ball screw vice's are the main considerations in this study. In order to ensure the rational of the design of the vertical lifting landing gear retraction mechanism,two main failure modes-static load failure and dynamic load failure of the main component of the lifting mechanism-the ball screw vice are analyzed and the reliability analysis model is established,then the reliability index is calculated.
2014, 33(11): 1768-1772.
doi: 10.13433/j.cnki.1003-8728.2014.1132
Abstract:
Modern aircraft landing gears are generally designed to be retractable to reduce the air resistance while flying. The nose landing gear emergency lowering system of a certain passenger aircraft failed to lock in some tests.Aiming at this problem,mechanical equilibrium equations of the extending-retracting mechanism and the gear-door linkage were set up for theoretical analysis. A virtual prototype of emergency lowering system for dynamics analysis was established with LMS Virtual. Lab /Motion to figure out the effect of external loads on the lowering process. The simulation results indicate that the aerodynamic force of front doors extremely prevents the landing gears from emergency lowering near the end of the whole trip. Using this analysis as a foundation,a door emergency disconnection mechanism was put forward. The dynamics model of the scheme was established and the feasibility of the scheme was validated through simulation.
Modern aircraft landing gears are generally designed to be retractable to reduce the air resistance while flying. The nose landing gear emergency lowering system of a certain passenger aircraft failed to lock in some tests.Aiming at this problem,mechanical equilibrium equations of the extending-retracting mechanism and the gear-door linkage were set up for theoretical analysis. A virtual prototype of emergency lowering system for dynamics analysis was established with LMS Virtual. Lab /Motion to figure out the effect of external loads on the lowering process. The simulation results indicate that the aerodynamic force of front doors extremely prevents the landing gears from emergency lowering near the end of the whole trip. Using this analysis as a foundation,a door emergency disconnection mechanism was put forward. The dynamics model of the scheme was established and the feasibility of the scheme was validated through simulation.
