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RSS2015 Vol. 34, No. 12
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2015, 34(12): 1805-1812.
doi: 10.13433/j.cnki.1003-8728.2015.1201
PDF 1225KB
Abstract:
To study the higher nonlinear behavior introduced by larger, lighter and more flexible wind turbine blade, an aero-elastic model with geometrically nonlinear beam is developed in this paper. The nonlinear beam based on geometrically exact beam theory contains the effects respectively of pre-bending, pre-twisting and eccentric shape. BEM theory is used because of its efficiency. The structure model is validated by two simulation cases. The static deflections of NREL 5MW offshore wind turbine blade show good agreement with results obtained by FAST. The natural frequencies and the responses under gust and yaw error conditions are also simulated. The responses of blade with reduced stiffness show more exactly results of the geometrically nonlinear aero-elastic model rather than the linear model.
To study the higher nonlinear behavior introduced by larger, lighter and more flexible wind turbine blade, an aero-elastic model with geometrically nonlinear beam is developed in this paper. The nonlinear beam based on geometrically exact beam theory contains the effects respectively of pre-bending, pre-twisting and eccentric shape. BEM theory is used because of its efficiency. The structure model is validated by two simulation cases. The static deflections of NREL 5MW offshore wind turbine blade show good agreement with results obtained by FAST. The natural frequencies and the responses under gust and yaw error conditions are also simulated. The responses of blade with reduced stiffness show more exactly results of the geometrically nonlinear aero-elastic model rather than the linear model.
2015, 34(12): 1813-1818.
doi: 10.13433/j.cnki.1003-8728.2015.1202
Abstract:
Aiming at the complex exploitation conditions of new-type oil and gas resources, we put forward a new-style PDC bit with whipstocking controllability to improve the wellborn quality of directional well on whipstocking segment. First, according to the design criterion of blade linear contour, we change the traditional conical curve on bit central pilot into the circular arc transitional curve which breaks through the limitations of traditional conical curve. Considering the key factors which affect the drill deflection ability, we established the mechanics analysis model of cutting teeth combined with cloth tooth parameters and actual drilling conditions, and then analyze bit whipstocking controllability. The research results show that: the heart conical curve of traditional PDC bit is the key factor to restrict bit deflection; its deflection ability has been improved a lot after changing conical curve into circular arc contour. Meanwhile, according to field test, we conducte the comparison between new-style PDC bit with whipstocking controllability and conventional PDC bit, and analyze the rock-breaking characteristic and deflecting ability. Findings above have important reference value for the research of rock-breaking mechanism and the development of directional drilling technology.
Aiming at the complex exploitation conditions of new-type oil and gas resources, we put forward a new-style PDC bit with whipstocking controllability to improve the wellborn quality of directional well on whipstocking segment. First, according to the design criterion of blade linear contour, we change the traditional conical curve on bit central pilot into the circular arc transitional curve which breaks through the limitations of traditional conical curve. Considering the key factors which affect the drill deflection ability, we established the mechanics analysis model of cutting teeth combined with cloth tooth parameters and actual drilling conditions, and then analyze bit whipstocking controllability. The research results show that: the heart conical curve of traditional PDC bit is the key factor to restrict bit deflection; its deflection ability has been improved a lot after changing conical curve into circular arc contour. Meanwhile, according to field test, we conducte the comparison between new-style PDC bit with whipstocking controllability and conventional PDC bit, and analyze the rock-breaking characteristic and deflecting ability. Findings above have important reference value for the research of rock-breaking mechanism and the development of directional drilling technology.
2015, 34(12): 1819-1824.
doi: 10.13433/j.cnki.1003-8728.2015.1203
Abstract:
For the requirements of obstacle crossing performance of the mobile robot in complex environments, a kind of barrier-crossing robot is proposed, which two-crank-slider is used to change the track shape. Introducing the passive adaptive installation, the track deformation of tension is actively controlled. The overall structure of the robot is introduced and the design of obstacle negotiation mechanism and implementation of the process are expounded. The track length which does not change before and after deformation is analyzed and verified. In order to check the effectiveness of the robot, the robot motion such as climbing, protrusion crossing and steering process is analyzed, and the simulation via ADAMS is carried out. The actual process of obstacle-navigation and steering task is imitated, then the surmounting obstacle and steering ability is verified.
For the requirements of obstacle crossing performance of the mobile robot in complex environments, a kind of barrier-crossing robot is proposed, which two-crank-slider is used to change the track shape. Introducing the passive adaptive installation, the track deformation of tension is actively controlled. The overall structure of the robot is introduced and the design of obstacle negotiation mechanism and implementation of the process are expounded. The track length which does not change before and after deformation is analyzed and verified. In order to check the effectiveness of the robot, the robot motion such as climbing, protrusion crossing and steering process is analyzed, and the simulation via ADAMS is carried out. The actual process of obstacle-navigation and steering task is imitated, then the surmounting obstacle and steering ability is verified.
2015, 34(12): 1825-1829.
doi: 10.13433/j.cnki.1003-8728.2015.1204
Abstract:
Because the general scroll profile conjugate meshing and the profile equation theory in the field of scroll compressor research are incomplete, we presented the related research information about control equation and general profile meshing conditions. Then we build a mathematical model of scroll profile conjugate meshing according to the actual work of the scroll compressor, which depends on the plane curve meshing theory, differential geometry and matrix algebra. The control equation was proved and discussed using vector expression; generalized meshing conditions of a general profile was illustrated in mathematical form; the certainty of scroll profile conjugate meshing in vector expression was verified through calculating the radius of curvature. Above all, full conditions of scroll profile conjugate meshing and the corresponding profile equations are given.
Because the general scroll profile conjugate meshing and the profile equation theory in the field of scroll compressor research are incomplete, we presented the related research information about control equation and general profile meshing conditions. Then we build a mathematical model of scroll profile conjugate meshing according to the actual work of the scroll compressor, which depends on the plane curve meshing theory, differential geometry and matrix algebra. The control equation was proved and discussed using vector expression; generalized meshing conditions of a general profile was illustrated in mathematical form; the certainty of scroll profile conjugate meshing in vector expression was verified through calculating the radius of curvature. Above all, full conditions of scroll profile conjugate meshing and the corresponding profile equations are given.
2015, 34(12): 1830-1836.
doi: 10.13433/j.cnki.1003-8728.2015.1205
Abstract:
In this paper, the construction process of a micro-segment involute spherical gear is discussed. The movement rule of contact ellipses of the spherical gear pairs is analyzed, and the curvatures of gear transmission and contact stress of the spherical gear pairs are calculated. The three dimensional model of the micro-segment involute spherical gear is built. Finite element method is applied to perform bending stress analysis and tooth contact stress analysis of micro-segment involute spherical gear. Compared with the involute spherical gear with the same parameters, it can conclude that the contact stress and the bending stress of micro-segment involute spherical gear have large reduction.
In this paper, the construction process of a micro-segment involute spherical gear is discussed. The movement rule of contact ellipses of the spherical gear pairs is analyzed, and the curvatures of gear transmission and contact stress of the spherical gear pairs are calculated. The three dimensional model of the micro-segment involute spherical gear is built. Finite element method is applied to perform bending stress analysis and tooth contact stress analysis of micro-segment involute spherical gear. Compared with the involute spherical gear with the same parameters, it can conclude that the contact stress and the bending stress of micro-segment involute spherical gear have large reduction.
2015, 34(12): 1837-1840.
doi: 10.13433/j.cnki.1003-8728.2015.1206
Abstract:
The theory of mobile robot behavioral dynamics is extended to three-dimensional space of manipulator, and is applied to the path planning in its work space. In this paper, the behavior of end-effector of manipulating robot reaching target is generated as the attractor in dynamical system, and behaviors of bypassing obstacles are generated as the repellors. The dynamic model of target acquisition and obstacle avoidance are established respectively, and these two kinds of behavior constitute an overall coupling and competitive robot dynamics model. Simulation and experimental results show that: under the control of the dynamics equations, the end-effector while avoiding obstacles can reach the target safely and effectively, demonstrating the effectiveness of the proposed method.
The theory of mobile robot behavioral dynamics is extended to three-dimensional space of manipulator, and is applied to the path planning in its work space. In this paper, the behavior of end-effector of manipulating robot reaching target is generated as the attractor in dynamical system, and behaviors of bypassing obstacles are generated as the repellors. The dynamic model of target acquisition and obstacle avoidance are established respectively, and these two kinds of behavior constitute an overall coupling and competitive robot dynamics model. Simulation and experimental results show that: under the control of the dynamics equations, the end-effector while avoiding obstacles can reach the target safely and effectively, demonstrating the effectiveness of the proposed method.
2015, 34(12): 1841-1845.
doi: 10.13433/j.cnki.1003-8728.2015.1207
Abstract:
Laying out stiffeners can enforce the strength of plates at the condition of not changing material cost. To find a best way of stiffener layout, a new method to design stiffener of plates and shells is presented in this paper based on the equivalence principle. In this method, the stiffener is equivalent to a piece of anisotropic plate because of its mechanical property in a different direction and it is possible to turn the design of stiffener into the design of anisotropic plate. The way of defining performance parameters of the anisotropic plate is presented and it is applied in the optimization design of car front rail.
Laying out stiffeners can enforce the strength of plates at the condition of not changing material cost. To find a best way of stiffener layout, a new method to design stiffener of plates and shells is presented in this paper based on the equivalence principle. In this method, the stiffener is equivalent to a piece of anisotropic plate because of its mechanical property in a different direction and it is possible to turn the design of stiffener into the design of anisotropic plate. The way of defining performance parameters of the anisotropic plate is presented and it is applied in the optimization design of car front rail.
2015, 34(12): 1846-1850.
doi: 10.13433/j.cnki.1003-8728.2015.1208
Abstract:
For low precision and inefficiency in detecting the coaxial error of piston rod, a method to inspect the coaxial error of piston rod based on the machine vision is presented. This method is proposed in terms of the principle of coaxial error, and then a model is developed. The piston image is acquired and the edge feature is extracted; the reference cylindrical surface is decomposed into 240 continuous cross-section, the testing cylindrical surface is divided into 110 continuous cross-section; the circum circle center of each cross-section based on the furthest Voronoi diagram is calculated, and the method of least squares fitting the axis of rod cylindrical surface is used. Datum axis are obtained in this way, thus the coaxial error of piston rod can be calculated. Experimental results of a certain piston rod showed that the present method is effectively evaluated and it is very close to the result measured by Coordinate Measuring Machining (CMM).
For low precision and inefficiency in detecting the coaxial error of piston rod, a method to inspect the coaxial error of piston rod based on the machine vision is presented. This method is proposed in terms of the principle of coaxial error, and then a model is developed. The piston image is acquired and the edge feature is extracted; the reference cylindrical surface is decomposed into 240 continuous cross-section, the testing cylindrical surface is divided into 110 continuous cross-section; the circum circle center of each cross-section based on the furthest Voronoi diagram is calculated, and the method of least squares fitting the axis of rod cylindrical surface is used. Datum axis are obtained in this way, thus the coaxial error of piston rod can be calculated. Experimental results of a certain piston rod showed that the present method is effectively evaluated and it is very close to the result measured by Coordinate Measuring Machining (CMM).
2015, 34(12): 1851-1856.
doi: 10.13433/j.cnki.1003-8728.2015.1209
Abstract:
For multi-view point cloud of registration, an automatic matching algorithm based on the spherical feature was proposed. The standard balls around the measurement parts was fixed, and then the parts and standard balls as a whole was been measured. The spherical center coordinates was found via spherical fitting. Then the corresponding points in the spherical center coordinates belong to the point cloud to be registered was searched, and the corresponding points to calculate the registration of rotation matrix and translation matrix was used, those was used to point cloud of coarse registration. Finally, an improved ICP (Iterative Closest Point) algorithm was used to integrate the sphere coordinate information center to the point cloud of precise registration. The present registration method greatly reduced the coarse registration of corresponding point search, and the automatic registration was been implemented. The present algorithm also improved the registration efficiency and the improved ICP algorithm enhances the robustness of matching algorithm. The examples verifies that the method is effective.
For multi-view point cloud of registration, an automatic matching algorithm based on the spherical feature was proposed. The standard balls around the measurement parts was fixed, and then the parts and standard balls as a whole was been measured. The spherical center coordinates was found via spherical fitting. Then the corresponding points in the spherical center coordinates belong to the point cloud to be registered was searched, and the corresponding points to calculate the registration of rotation matrix and translation matrix was used, those was used to point cloud of coarse registration. Finally, an improved ICP (Iterative Closest Point) algorithm was used to integrate the sphere coordinate information center to the point cloud of precise registration. The present registration method greatly reduced the coarse registration of corresponding point search, and the automatic registration was been implemented. The present algorithm also improved the registration efficiency and the improved ICP algorithm enhances the robustness of matching algorithm. The examples verifies that the method is effective.
2015, 34(12): 1857-1862.
doi: 10.13433/j.cnki.1003-8728.2015.1210
Abstract:
Electrochemical machining (ECM) is one of the main technologies to produce complex curved surface part, such as blade and blisk. The θ angles, which between the feeding direction and the workpiece surface normal directions, is a critical factor affecting the ECM processing accuracy. The traditional method is to use the variance of θ angles as the objective function. In the optimization of complex curved surface with curvature mutation, the traditional method is limited. In order to reduce the θ angles on whole curved surface, a novel optimization method of tool spatial feeding direction evaluated by the maximum θ angle was proposed. Taking blade complex parts as example, the optimization experiment was carried out with the traditional and novel method. The results revealed that the θ angle distribution was more uniform with new optimization method. Based on the best spatial feeding directions of traditional and novel optimization method, the processing experiment of ECM blades was carried out. The present result shows that the specimen with novel optimization method has better contour accuracy. The feasibility of optimization method has been proved.
Electrochemical machining (ECM) is one of the main technologies to produce complex curved surface part, such as blade and blisk. The θ angles, which between the feeding direction and the workpiece surface normal directions, is a critical factor affecting the ECM processing accuracy. The traditional method is to use the variance of θ angles as the objective function. In the optimization of complex curved surface with curvature mutation, the traditional method is limited. In order to reduce the θ angles on whole curved surface, a novel optimization method of tool spatial feeding direction evaluated by the maximum θ angle was proposed. Taking blade complex parts as example, the optimization experiment was carried out with the traditional and novel method. The results revealed that the θ angle distribution was more uniform with new optimization method. Based on the best spatial feeding directions of traditional and novel optimization method, the processing experiment of ECM blades was carried out. The present result shows that the specimen with novel optimization method has better contour accuracy. The feasibility of optimization method has been proved.
2015, 34(12): 1863-1868.
doi: 10.13433/j.cnki.1003-8728.2015.1211
Abstract:
Reliability allocation is a collection problem of engineering decision, multi factor comprehensive balance and process optimization. According to the factors affecting reliability allocation and their weights with the uncertainty, we put forward a subjective and objective combination weighting method coupling the entropy method and fuzzy analytic hierarchy process (FAHP) method. Taking CNC grinding machine as an example, considering the system failure frequency, harmfulness, complexity, maintainability, technical level and the ratio of cost to performance, firstly, we establish the reliability objective function based on the minimum discrimination information principle, and employ the Lagrange multiplier method to get the combined weights of the six factors. Then the fuzzy comprehensive allocation method based on the combined weights method was used to obtain the reliability allocation results, which was compared with the actual accumulated data, therefore, the feasibility and effectiveness of the present method was verified.
Reliability allocation is a collection problem of engineering decision, multi factor comprehensive balance and process optimization. According to the factors affecting reliability allocation and their weights with the uncertainty, we put forward a subjective and objective combination weighting method coupling the entropy method and fuzzy analytic hierarchy process (FAHP) method. Taking CNC grinding machine as an example, considering the system failure frequency, harmfulness, complexity, maintainability, technical level and the ratio of cost to performance, firstly, we establish the reliability objective function based on the minimum discrimination information principle, and employ the Lagrange multiplier method to get the combined weights of the six factors. Then the fuzzy comprehensive allocation method based on the combined weights method was used to obtain the reliability allocation results, which was compared with the actual accumulated data, therefore, the feasibility and effectiveness of the present method was verified.
2015, 34(12): 1869-1873.
doi: 10.13433/j.cnki.1003-8728.2015.1212
Abstract:
To suppress the vibration of the wire, this paper researches suppression principle and control effects of the wire guides which be used for the wire vibration. LMS.Test.Lab test system was used for measuring the WEDM-HS (high-speed wire-cut electrical discharge machining)modal parameters and PSD (power spectral density). The measurement data as input stimulus, is used for the dynamics analysis of wire electrode in the Ansys Workbench. Comparing the results of the analysis, in the first place, wire guides can reduce the amplitude of vibration of wire electrode itself. In the second place, it can isolate vibration from machine running vibration. Both supplement each other work together. After installing the wire guides,vibration of the electrode wire in the working condition of deformation is reduced by a factor of 10, controling the wire electrode vibration effectively.
To suppress the vibration of the wire, this paper researches suppression principle and control effects of the wire guides which be used for the wire vibration. LMS.Test.Lab test system was used for measuring the WEDM-HS (high-speed wire-cut electrical discharge machining)modal parameters and PSD (power spectral density). The measurement data as input stimulus, is used for the dynamics analysis of wire electrode in the Ansys Workbench. Comparing the results of the analysis, in the first place, wire guides can reduce the amplitude of vibration of wire electrode itself. In the second place, it can isolate vibration from machine running vibration. Both supplement each other work together. After installing the wire guides,vibration of the electrode wire in the working condition of deformation is reduced by a factor of 10, controling the wire electrode vibration effectively.
2015, 34(12): 1874-1879.
doi: 10.13433/j.cnki.1003-8728.2015.1213
Abstract:
In order to improve the efficiency of dust fall for continuous miner external spray, we ameliorate the safety engineering and working environment with spray pressure, effective length of spray, spray diffusion angle, nozzle diameter and overlay parameter of border upon section circle as design variables. Then we establish the maximum efficiency functions of dust fall as optimal objective, globally optimize the dust fall parameters for 2 to 8 μm with the genetic algorithm with ant algorithm(GAAA). Finally we conducted the computer simulation of the flow fields. The simulation results show that the average dust fall efficiency decreases after increase and that the water consumption gradually increases with the increasing size of dust. The optimal parameters make the average dust fall computational efficiency reach 90.9% and increase by 7.5%, and the water consumption decreases by 6.0%. All these have important significance for the preventing accidents of underground coal mining.
In order to improve the efficiency of dust fall for continuous miner external spray, we ameliorate the safety engineering and working environment with spray pressure, effective length of spray, spray diffusion angle, nozzle diameter and overlay parameter of border upon section circle as design variables. Then we establish the maximum efficiency functions of dust fall as optimal objective, globally optimize the dust fall parameters for 2 to 8 μm with the genetic algorithm with ant algorithm(GAAA). Finally we conducted the computer simulation of the flow fields. The simulation results show that the average dust fall efficiency decreases after increase and that the water consumption gradually increases with the increasing size of dust. The optimal parameters make the average dust fall computational efficiency reach 90.9% and increase by 7.5%, and the water consumption decreases by 6.0%. All these have important significance for the preventing accidents of underground coal mining.
2015, 34(12): 1880-1884.
doi: 10.13433/j.cnki.1003-8728.2015.1214
Abstract:
The crimping quality is often influenced by uncertain factors such as the material performance parameters, which will frequently lead to the product materials' constants. To resolve this issue, the crimping is simulated with the FE code ABAQUS and the FE model is validated experimentally. Based on the present analysis, the stochastic analysis based on the stochastic model is used to obtain the probability distribution of crimping quality and the sensitivity analysis.
The crimping quality is often influenced by uncertain factors such as the material performance parameters, which will frequently lead to the product materials' constants. To resolve this issue, the crimping is simulated with the FE code ABAQUS and the FE model is validated experimentally. Based on the present analysis, the stochastic analysis based on the stochastic model is used to obtain the probability distribution of crimping quality and the sensitivity analysis.
2015, 34(12): 1885-1890.
doi: 10.13433/j.cnki.1003-8728.2015.1215
Abstract:
At present, the results of fault diagnosis of CNC machine tools are explanations of text or text and picture mixed. In order to improve this situation, this paper puts forward a new method for reading 3-D models and writing mouse events and optimizing hug data on the Web. With understanding of Obj format file, the paper proposes algorithms of extracting file data and signing fault parts or the surface of fault parts. Combining with the API function of the OpenGL interface, this method can be used to draw the 3-D model on the Web for fault diagnosis of CNC machine tools, rules or case outputs. By optimizing the process of initial files, the users can sign the fault parts clearly to help maintenance workers repair the machine to reduce the economic loss and bad effect caused by downtime.
At present, the results of fault diagnosis of CNC machine tools are explanations of text or text and picture mixed. In order to improve this situation, this paper puts forward a new method for reading 3-D models and writing mouse events and optimizing hug data on the Web. With understanding of Obj format file, the paper proposes algorithms of extracting file data and signing fault parts or the surface of fault parts. Combining with the API function of the OpenGL interface, this method can be used to draw the 3-D model on the Web for fault diagnosis of CNC machine tools, rules or case outputs. By optimizing the process of initial files, the users can sign the fault parts clearly to help maintenance workers repair the machine to reduce the economic loss and bad effect caused by downtime.
2015, 34(12): 1891-1895.
doi: 10.13433/j.cnki.1003-8728.2015.1216
Abstract:
Mass property parameters are important basic parameters of aircraft. In order to accurately measure the mass property parameters of large scale aircraft model, this paper presents a measuring method which combines the four-point approach and the dynamic approach to measure mass, centroid, centroidal deviation and moments of inertia. The principle of measurement is described and the measurement errors are analyzed. The integrated mass property parameters measuring device is developed for large scale aircraft model and the all the parameters can be measured in one installation. Experimental results show this method has a high precision and other advantages such as less clamping process, convenient operation, high efficiency and good stability.
Mass property parameters are important basic parameters of aircraft. In order to accurately measure the mass property parameters of large scale aircraft model, this paper presents a measuring method which combines the four-point approach and the dynamic approach to measure mass, centroid, centroidal deviation and moments of inertia. The principle of measurement is described and the measurement errors are analyzed. The integrated mass property parameters measuring device is developed for large scale aircraft model and the all the parameters can be measured in one installation. Experimental results show this method has a high precision and other advantages such as less clamping process, convenient operation, high efficiency and good stability.
Research on Asynchronous Motor Direct Torque Control System Based on Sliding Mode Variable Structure
2015, 34(12): 1896-1902.
doi: 10.13433/j.cnki.1003-8728.2015.1217
Abstract:
On the fact of the torque ripple is larger in the traditional direct torque control(DTC)system of the asynchronous motor and the problems of speed performance is made slow by the changing motor parameters and the loading fluctuations,this article puts forward a new idea. In same words, the idea is that the traditional PI controller is replaced by speed controller of sliding mode variable structure (SMVS). What is more, according to the mathematical models of induction motor in synchronous rotation coordinates and control theory of sliding mode variable structure, we propose a new variable structure sliding mode controller based on torque and flux errors. Using the reference voltage vectors which are the outputs of the controller,the switching control signals of the inverter are generated by space vector PWM(SVPWM) technology. The MATLAB simulation verifies that the proposed control scheme significantly reduces torque and flux ripple,ensures the inverter switching frequency to be fixed,and it also has strong robustness to motor parameter and disturbance.
On the fact of the torque ripple is larger in the traditional direct torque control(DTC)system of the asynchronous motor and the problems of speed performance is made slow by the changing motor parameters and the loading fluctuations,this article puts forward a new idea. In same words, the idea is that the traditional PI controller is replaced by speed controller of sliding mode variable structure (SMVS). What is more, according to the mathematical models of induction motor in synchronous rotation coordinates and control theory of sliding mode variable structure, we propose a new variable structure sliding mode controller based on torque and flux errors. Using the reference voltage vectors which are the outputs of the controller,the switching control signals of the inverter are generated by space vector PWM(SVPWM) technology. The MATLAB simulation verifies that the proposed control scheme significantly reduces torque and flux ripple,ensures the inverter switching frequency to be fixed,and it also has strong robustness to motor parameter and disturbance.
2015, 34(12): 1903-1907.
doi: 10.13433/j.cnki.1003-8728.2015.1218
Abstract:
The traditional point-by-point comparison algorithm has the shortcomings that its interpolation efficiency and accuracy are not high and that the feed pulse distribution is uneven. Therefore we establish the deviation discrimination algorithm through building a new deviation discrimination function to determine the direction of feeding. At the same time, we use the dsPIC30F5015 digital signal controller as the hardware control core and then design the hardware system. With the help of the MPLAB-IDE software development environment, we use the C language to design the traditional point-by-point comparison algorithm. The results on interpolation simulation with MATLAB show that: compared with the traditional point-by-point comparison algorithm, the deviation discrimination algorithm improves the interpolation efficiency by more than 30%; the interpolation accuracy by more than 50%; the feed pulse produced by dsPIC is much more uniform.
The traditional point-by-point comparison algorithm has the shortcomings that its interpolation efficiency and accuracy are not high and that the feed pulse distribution is uneven. Therefore we establish the deviation discrimination algorithm through building a new deviation discrimination function to determine the direction of feeding. At the same time, we use the dsPIC30F5015 digital signal controller as the hardware control core and then design the hardware system. With the help of the MPLAB-IDE software development environment, we use the C language to design the traditional point-by-point comparison algorithm. The results on interpolation simulation with MATLAB show that: compared with the traditional point-by-point comparison algorithm, the deviation discrimination algorithm improves the interpolation efficiency by more than 30%; the interpolation accuracy by more than 50%; the feed pulse produced by dsPIC is much more uniform.
2015, 34(12): 1908-1913.
doi: 10.13433/j.cnki.1003-8728.2015.1219
Abstract:
A new common pressure rail (CPR) slewing energy recovery system with two accumulators was proposed for a hybrid hydraulic excavator in order to achieve energy recycling. Taking into account the influence of gas temperature and heat transfer on the accumulators' operating characteristics, we built its mathematical model. For braking stability, an adaptive fuzzy sliding mode controller was created to control the speed of the slewing mechanism. The analysis of simulation results with MATLAB software shows that the adaptive fuzzy sliding mode controller with good stability and robustness can control the speed steadily and can eliminate the pressure disturbance between secondary components in the CPR system. The slewing energy recovery system thus designed can increase the rotation speed of the CPR system up to 49.8% of the total, 16.7% more than the same tonnage excavators.
A new common pressure rail (CPR) slewing energy recovery system with two accumulators was proposed for a hybrid hydraulic excavator in order to achieve energy recycling. Taking into account the influence of gas temperature and heat transfer on the accumulators' operating characteristics, we built its mathematical model. For braking stability, an adaptive fuzzy sliding mode controller was created to control the speed of the slewing mechanism. The analysis of simulation results with MATLAB software shows that the adaptive fuzzy sliding mode controller with good stability and robustness can control the speed steadily and can eliminate the pressure disturbance between secondary components in the CPR system. The slewing energy recovery system thus designed can increase the rotation speed of the CPR system up to 49.8% of the total, 16.7% more than the same tonnage excavators.
2015, 34(12): 1914-1918.
doi: 10.13433/j.cnki.1003-8728.2015.1220
Abstract:
The viewpoint that heat partition coefficient affected by the circumferential contact arc length of the brake pair was brought forward. The circumferential contact arc length and the heat partition coefficient, which was changing with radial distance, were determined by quadratic interpolation function method. The temperature and its distributions of the brake pad were calculated and compared by two different thermal loads based on Energy Balance Law. The results show that the circumferential contact arc length will increase firstly and then decrease with the increase of radial distance, while the heat partition coefficient is in the opposite situation. Although the time when peak temperatures happen of two different thermal loads are almost the same, the temperature difference is high and it also has a different temperature distribution both in axial and radial direction of the pad. Therefore, the geometry of the brake pad must be taken into the consideration during the thermal analysis of brake pair.
The viewpoint that heat partition coefficient affected by the circumferential contact arc length of the brake pair was brought forward. The circumferential contact arc length and the heat partition coefficient, which was changing with radial distance, were determined by quadratic interpolation function method. The temperature and its distributions of the brake pad were calculated and compared by two different thermal loads based on Energy Balance Law. The results show that the circumferential contact arc length will increase firstly and then decrease with the increase of radial distance, while the heat partition coefficient is in the opposite situation. Although the time when peak temperatures happen of two different thermal loads are almost the same, the temperature difference is high and it also has a different temperature distribution both in axial and radial direction of the pad. Therefore, the geometry of the brake pad must be taken into the consideration during the thermal analysis of brake pair.
2015, 34(12): 1919-1923.
doi: 10.13433/j.cnki.1003-8728.2015.1221
Abstract:
An experimental study of the noise source identification of a 4-cylinder dual-fuel engine based on beamforming technology was presented. The experiment uses idle conditions, maximum torque conditions and maximum power conditions. Firstly, the noise pressure level measurement shows that the noisiest surface was in the front of the engine. Secondly the main noise sources were identified with a beamformer array. The experimental results showed that the major noise source in 1 000~2 000 Hz was the chain cover both in gasoline fuel and CNG fuel. Vibration analysis was done to verify the experimental results. Additionally, the characteristics of noise sources of the two types of fuel were compared. This study shows that the beamforming technology in the noise source identification is fast. The noise of CNG fuel is 5~7 dB bigger than that of gasoline fuel in the idle condition because the combustion noise is below 250 Hz.
An experimental study of the noise source identification of a 4-cylinder dual-fuel engine based on beamforming technology was presented. The experiment uses idle conditions, maximum torque conditions and maximum power conditions. Firstly, the noise pressure level measurement shows that the noisiest surface was in the front of the engine. Secondly the main noise sources were identified with a beamformer array. The experimental results showed that the major noise source in 1 000~2 000 Hz was the chain cover both in gasoline fuel and CNG fuel. Vibration analysis was done to verify the experimental results. Additionally, the characteristics of noise sources of the two types of fuel were compared. This study shows that the beamforming technology in the noise source identification is fast. The noise of CNG fuel is 5~7 dB bigger than that of gasoline fuel in the idle condition because the combustion noise is below 250 Hz.
2015, 34(12): 1924-1928.
doi: 10.13433/j.cnki.1003-8728.2015.1222
Abstract:
In this paper, the calculation algorithm of the wheel-rail relative sliding velocity taking both the rigid and elastic deformations in the contact patch into consideration was derived. A theoretical calculation models to predict the railway wheel wear and the numerical analysis program were developed, including the coupling dynamics model of vehicle and bridge, a wheel material wear model and the rolling contact model of wheel and rail system. The influence of four typical wheel diameter differences on wheel wear in the process of vehicle-bridge coupling is analyzed with the models. The results indicate that wheel diameter difference not only results in the wheel eccentric wear, but also causes the changes of the wear region of wheel tread.
In this paper, the calculation algorithm of the wheel-rail relative sliding velocity taking both the rigid and elastic deformations in the contact patch into consideration was derived. A theoretical calculation models to predict the railway wheel wear and the numerical analysis program were developed, including the coupling dynamics model of vehicle and bridge, a wheel material wear model and the rolling contact model of wheel and rail system. The influence of four typical wheel diameter differences on wheel wear in the process of vehicle-bridge coupling is analyzed with the models. The results indicate that wheel diameter difference not only results in the wheel eccentric wear, but also causes the changes of the wear region of wheel tread.
2015, 34(12): 1929-1934.
doi: 10.13433/j.cnki.1003-8728.2015.1223
Abstract:
This paper uses gradient optimization method and global optimization method to optimize the design of the pit-type non-smooth unit, seeking the best drag reduction effect on the car body by adding non-smooth structures. The pit-type non-smooth structure is arranged on different locations of a container truck model, the difference in drag reduction effect is compared to determine the effective drag reduction position of the model. The pit-type non-smooth structure's design variables of aperture diameter, depth, vertical spacing, and horizontal spacing were optimized using the gradient method and the global optimization method respectively; the differences between the two methods were compared. The results and their discussion show preliminarily that: the gradient method can quickly obtain optimization program for practical engineering; global optimization method takes the variable coupling factor into account and its optimization results are more comprehensive and accurate; after optimization, pit-type non-smooth structure can effectively reduce the aerodynamic drag up to 10.44%.
This paper uses gradient optimization method and global optimization method to optimize the design of the pit-type non-smooth unit, seeking the best drag reduction effect on the car body by adding non-smooth structures. The pit-type non-smooth structure is arranged on different locations of a container truck model, the difference in drag reduction effect is compared to determine the effective drag reduction position of the model. The pit-type non-smooth structure's design variables of aperture diameter, depth, vertical spacing, and horizontal spacing were optimized using the gradient method and the global optimization method respectively; the differences between the two methods were compared. The results and their discussion show preliminarily that: the gradient method can quickly obtain optimization program for practical engineering; global optimization method takes the variable coupling factor into account and its optimization results are more comprehensive and accurate; after optimization, pit-type non-smooth structure can effectively reduce the aerodynamic drag up to 10.44%.
2015, 34(12): 1935-1939.
doi: 10.13433/j.cnki.1003-8728.2015.1224
Abstract:
In order to research the generation mechanism of gasoline engine's combustion noise, and achieve the goal to predict the combustion noise in the engine design phase, a method of combustion pressure calculation based on the gasoline engine's in-cylinder pressure and compression pressure is proposed. The time and frequency spectrum analysis about in-cylinder pressure、compression pressure、combustion pressure and gas resonance excitation are studied with Fast Fourier Transform (FFT) technology, and then the contribution of combustion noise in each frequency band range is confirmed. The theoretical analysis results show that the low frequency (15 kHz) is a consequence of the acoustic noise caused by gas resonance in cylinder. The gasoline engine's rotating speed has a strong influence on combustion noise in middle frequency bands.
In order to research the generation mechanism of gasoline engine's combustion noise, and achieve the goal to predict the combustion noise in the engine design phase, a method of combustion pressure calculation based on the gasoline engine's in-cylinder pressure and compression pressure is proposed. The time and frequency spectrum analysis about in-cylinder pressure、compression pressure、combustion pressure and gas resonance excitation are studied with Fast Fourier Transform (FFT) technology, and then the contribution of combustion noise in each frequency band range is confirmed. The theoretical analysis results show that the low frequency (15 kHz) is a consequence of the acoustic noise caused by gas resonance in cylinder. The gasoline engine's rotating speed has a strong influence on combustion noise in middle frequency bands.
2015, 34(12): 1940-1946.
doi: 10.13433/j.cnki.1003-8728.2015.1225
Abstract:
An engine mounting system optimization model was established based on the multi-objective optimization theory, and the maximum energy decoupling rate of main vibration directions had been obtained by reasonable setting of mounting stiffness and position parameters. A 6-DOF model for mounting system was constructed with the maximization of energy decoupling rate of vertical and crankshaft rotation directions as optimization objectives, electing the mounting stiffness parameters and position parameters as optimization design variables. Taking into account of constraints of the natural frequency and engine mounting system parameters and using non-dominated sorting genetic algorithm, a multi-objective optimization was conducted to this system. Finally, the present method was applied to a practical vehicle engine mounting system.
An engine mounting system optimization model was established based on the multi-objective optimization theory, and the maximum energy decoupling rate of main vibration directions had been obtained by reasonable setting of mounting stiffness and position parameters. A 6-DOF model for mounting system was constructed with the maximization of energy decoupling rate of vertical and crankshaft rotation directions as optimization objectives, electing the mounting stiffness parameters and position parameters as optimization design variables. Taking into account of constraints of the natural frequency and engine mounting system parameters and using non-dominated sorting genetic algorithm, a multi-objective optimization was conducted to this system. Finally, the present method was applied to a practical vehicle engine mounting system.
2015, 34(12): 1947-1951.
doi: 10.13433/j.cnki.1003-8728.2015.1226
Abstract:
In order to compare the influence of different data processing method on the dynamic performance of a locomotive, we use the multi-rigid-body dynamics software SIMPACK to establish the dynamic model of some high-power AC drive electric locomotive, process the simulation results of the locomotive that dynamically negotiates the 300m radius curve with different methods and compare them with the test results. The test results show that: 1) the data processing method has a great influence on the dynamic performance of the locomotive that negotiates the small radius curve. The statistics of the wheel-set lateral force and wheel load rate on the sliding mode over 2m is smaller than that over a quarter circumference for 9.84%~20.22%, and it changes more smoothly than the results over a quarter circumference at the same time. The high frequency interference signal of the derailment coefficient has been obviously eliminated after the sliding mode, and the statistics of derailment coefficient after sliding mean is reduced by 17.95%~21.21%. 2) The larger the track irregularity, the more the percentage of the same index changes after different processes, and the greater the influence of data processing method on the dynamic performance of the locomotive. 3) The track irregularity used in the simulation for the evaluation value in the test of each dynamic index is larger than that for the average value. For different lines, the difference of each direction is not the same. Therefore, it is necessary to consider the difference of the data processing method and irregularity in future analysis to make the simulation results in better agreement with the test results.
In order to compare the influence of different data processing method on the dynamic performance of a locomotive, we use the multi-rigid-body dynamics software SIMPACK to establish the dynamic model of some high-power AC drive electric locomotive, process the simulation results of the locomotive that dynamically negotiates the 300m radius curve with different methods and compare them with the test results. The test results show that: 1) the data processing method has a great influence on the dynamic performance of the locomotive that negotiates the small radius curve. The statistics of the wheel-set lateral force and wheel load rate on the sliding mode over 2m is smaller than that over a quarter circumference for 9.84%~20.22%, and it changes more smoothly than the results over a quarter circumference at the same time. The high frequency interference signal of the derailment coefficient has been obviously eliminated after the sliding mode, and the statistics of derailment coefficient after sliding mean is reduced by 17.95%~21.21%. 2) The larger the track irregularity, the more the percentage of the same index changes after different processes, and the greater the influence of data processing method on the dynamic performance of the locomotive. 3) The track irregularity used in the simulation for the evaluation value in the test of each dynamic index is larger than that for the average value. For different lines, the difference of each direction is not the same. Therefore, it is necessary to consider the difference of the data processing method and irregularity in future analysis to make the simulation results in better agreement with the test results.
2015, 34(12): 1952-1955.
doi: 10.13433/j.cnki.1003-8728.2015.1227
Abstract:
In order to enhance the anti-rolling of vehicle, a kind of active anti-roll controller(ARC) is designed and an eight-DOF dynamic model is built up based on the platform of Matlab/Simulink. The ARC is controlled with PID theory. Two kinds of typical cases including turn in emergency and slalom testing are simulated and the simulations prove that the active anti-roll controller will greatly reduce the roll angle of vehicle when cornering. It can also reduce the transfer rate of lateral load and have a good influence on the operability and stability of the vehicle.
In order to enhance the anti-rolling of vehicle, a kind of active anti-roll controller(ARC) is designed and an eight-DOF dynamic model is built up based on the platform of Matlab/Simulink. The ARC is controlled with PID theory. Two kinds of typical cases including turn in emergency and slalom testing are simulated and the simulations prove that the active anti-roll controller will greatly reduce the roll angle of vehicle when cornering. It can also reduce the transfer rate of lateral load and have a good influence on the operability and stability of the vehicle.
2015, 34(12): 1956-1960.
doi: 10.13433/j.cnki.1003-8728.2015.1228
Abstract:
According to the basic procedures of bulging pressing compound-deforming of automobile axle housing, we simulate the pressing process with the finite element simulation software ABAQUS, study the influence of mold movement method and internal pressure on the quality of automobile axle housing in the pressing process, determine the best mold movement pattern and the size of internal pressure, and analyze the wall thickness distribution of the ideal automobile axle housing. Computer simulation results show that: 1) during the pressing process of bulging-pressing compound-deforming of automobile axle housing, when the pressing mold is moving and the internal loading pressure is 30 MPa, the automobile axle housing has the best quality; 2) with the best condition, the thinnest wall appears in the center of forming part and the thinnest wall is 3.2 mm and bigger than the initial design thickness. The automobile axle housing contour is clear; the fillet size is appropriate; there is no rupture or fly edge failure. All these meet the design requirements for automobile axle housing.
According to the basic procedures of bulging pressing compound-deforming of automobile axle housing, we simulate the pressing process with the finite element simulation software ABAQUS, study the influence of mold movement method and internal pressure on the quality of automobile axle housing in the pressing process, determine the best mold movement pattern and the size of internal pressure, and analyze the wall thickness distribution of the ideal automobile axle housing. Computer simulation results show that: 1) during the pressing process of bulging-pressing compound-deforming of automobile axle housing, when the pressing mold is moving and the internal loading pressure is 30 MPa, the automobile axle housing has the best quality; 2) with the best condition, the thinnest wall appears in the center of forming part and the thinnest wall is 3.2 mm and bigger than the initial design thickness. The automobile axle housing contour is clear; the fillet size is appropriate; there is no rupture or fly edge failure. All these meet the design requirements for automobile axle housing.
2015, 34(12): 1961-1965.
doi: 10.13433/j.cnki.1003-8728.2015.1229
Abstract:
As the key component of FSW machine, the fatigue damage and the wear behavior of the stirring head directly affect the welding process. A computational fluid dynamics (CFD) model for friction stir welded AA6061-T6 was developed to analyze the pressure distribution around the stirring head. The Results indicate that the transverse force consists of the frictional force from the shoulder, pressure force from the pin and the frictional force from the pin tip. Based on the calculated loads on the pin, the fatigue stress variations at the root of the pin were further studied in different rotating speeds.
As the key component of FSW machine, the fatigue damage and the wear behavior of the stirring head directly affect the welding process. A computational fluid dynamics (CFD) model for friction stir welded AA6061-T6 was developed to analyze the pressure distribution around the stirring head. The Results indicate that the transverse force consists of the frictional force from the shoulder, pressure force from the pin and the frictional force from the pin tip. Based on the calculated loads on the pin, the fatigue stress variations at the root of the pin were further studied in different rotating speeds.
2015, 34(12): 1966-1970.
doi: 10.13433/j.cnki.1003-8728.2015.1230
Abstract:
The abrasive belt grinding for ZrO2 Engineering Ceramics are carried out with four different abrasive belts. The orthogonal test with zirconia-corundum belt was to get the best grinding parameter, the amount of material removal workpiece surface roughness and belt wear were measured to get the best grinding parameter. The influence of abrasive belt granularity and different grinding parameters to grinding efficiency and workpiece surface quality in the all grinding process of ZrO2 Engineering Ceramics was analyzed. The wear mechanism of engineering ceramics based on the Abrasive cutting model by observing the surface morphology was analyzed. The results show that to increase the grinding force or the abrasive belt granularity can decrease the surface roughness of workpiece. With the abrasive belt speed or grinding force increasing, the material removal rate and the wear ratio increased to some extent, but brittle fracture easily occurred on its surface when exceeding the critical value; the grinding force is 15 N and the abrasive belt granularity is 120# at an abrasive belt speed of 19 m/s, the grinding effect of ZrO2 Engineering Ceramics was the best.
The abrasive belt grinding for ZrO2 Engineering Ceramics are carried out with four different abrasive belts. The orthogonal test with zirconia-corundum belt was to get the best grinding parameter, the amount of material removal workpiece surface roughness and belt wear were measured to get the best grinding parameter. The influence of abrasive belt granularity and different grinding parameters to grinding efficiency and workpiece surface quality in the all grinding process of ZrO2 Engineering Ceramics was analyzed. The wear mechanism of engineering ceramics based on the Abrasive cutting model by observing the surface morphology was analyzed. The results show that to increase the grinding force or the abrasive belt granularity can decrease the surface roughness of workpiece. With the abrasive belt speed or grinding force increasing, the material removal rate and the wear ratio increased to some extent, but brittle fracture easily occurred on its surface when exceeding the critical value; the grinding force is 15 N and the abrasive belt granularity is 120# at an abrasive belt speed of 19 m/s, the grinding effect of ZrO2 Engineering Ceramics was the best.
2015, 34(12): 1971-1974.
doi: 10.13433/j.cnki.1003-8728.2015.1231
Abstract:
The health monitoring of the cracked structure repaired by the composite patch via Lamb wave propagation was investigated. Composite repairs were performed to the cracked specimen. Three piezoelectric sensors were installed around the composite patch. The piezoelectric sensor response was periodically recorded in the fatigue testing. Three types of the damage index based on the piezoelectric sensor response were selected and calculated to describe the health state of the cracked specimen repaired by the composite patch. The results show that the damage index based on the waveform relativity has the best correlations with the expanding process of the damage of repaired specimen. The present monitoring method was successfully applied to test a full scale aircraft structure fatigue.
The health monitoring of the cracked structure repaired by the composite patch via Lamb wave propagation was investigated. Composite repairs were performed to the cracked specimen. Three piezoelectric sensors were installed around the composite patch. The piezoelectric sensor response was periodically recorded in the fatigue testing. Three types of the damage index based on the piezoelectric sensor response were selected and calculated to describe the health state of the cracked specimen repaired by the composite patch. The results show that the damage index based on the waveform relativity has the best correlations with the expanding process of the damage of repaired specimen. The present monitoring method was successfully applied to test a full scale aircraft structure fatigue.
