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RSS2017 Vol. 36, No. 12
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2017, 36(12): 1805-1809.
doi: 10.13433/j.cnki.1003-8728.2017.1201
PDF 963KB
Abstract:
To study the influence of cell inconsistency on battery pack, we established a non-rechargeable parallel grouping model of lithium batteries, based on the rechargeable parallel model of lithium batteries. The simulating flow chart is shown and the grouping characteristics are studied and analyzed. By comparing the result of rechargeable parallel batteries and that of non-rechargeable parallel batteries, it can be concluded that considering the cell battery inconsistency, the non-rechargeable battery pack behaves better than the rechargeable battery pack in terms of safety and utilization efficiency.
To study the influence of cell inconsistency on battery pack, we established a non-rechargeable parallel grouping model of lithium batteries, based on the rechargeable parallel model of lithium batteries. The simulating flow chart is shown and the grouping characteristics are studied and analyzed. By comparing the result of rechargeable parallel batteries and that of non-rechargeable parallel batteries, it can be concluded that considering the cell battery inconsistency, the non-rechargeable battery pack behaves better than the rechargeable battery pack in terms of safety and utilization efficiency.
2017, 36(12): 1810-1815.
doi: 10.13433/j.cnki.1003-8728.2017.1202
Abstract:
Tunnel Boring Machine(TBM)is a large equipment used in tunnelling construction. In order to analyse the influence of main factors such as geological parameters and operating condition to boring power, the mechanical characteristics of driving process are studied. The thrust and the cutter disc drive torque are obtained by main factors affecting the tunneling process. Based on the relationship between input energy consumption and load, the approximate estimation model of boring power is established. Moreover, engineering data is used to identify the coefficients of the model, which depend on specific conditions. Furthermore, the applicability and effectiveness of the model are discussed with independent data which is not used in modeling process. The comparison between measured and predicted values shows that the proposed model can reflect the influences of the key factors such as operating status, geological parameters.
Tunnel Boring Machine(TBM)is a large equipment used in tunnelling construction. In order to analyse the influence of main factors such as geological parameters and operating condition to boring power, the mechanical characteristics of driving process are studied. The thrust and the cutter disc drive torque are obtained by main factors affecting the tunneling process. Based on the relationship between input energy consumption and load, the approximate estimation model of boring power is established. Moreover, engineering data is used to identify the coefficients of the model, which depend on specific conditions. Furthermore, the applicability and effectiveness of the model are discussed with independent data which is not used in modeling process. The comparison between measured and predicted values shows that the proposed model can reflect the influences of the key factors such as operating status, geological parameters.
2017, 36(12): 1816-1822.
doi: 10.13433/j.cnki.1003-8728.2017.1203
Abstract:
With dual chamber self-excited oscillation pulsed jet nozzle as the research object, changing the structure of the second stage chamber as the variables, the inner and outer flow fields of the jet nozzle were simulated by using FLUENT. These studies are based on the theories of transient flow and underwater acoustics, and combined with the standard κ-ε model. The structural chamber of the strongest hitting power is obtained, and hitting power was compared with self-excited oscillation pulsed jet nozzle. Research results show that the nozzle has the largest hitting power with optimal cavity length, cavity diameter and downstream collision wall shape of the nozzle, and hitting power of self-excited oscillation pulsed jet nozzle is more than the single chamber 13.2%. An experiment was built to make the erosion test, erosion law of rock was analyzed, and erosion volume and depth were computed. The results show that the best structure of the nozzle is in agreement with the numerical simulation; Compared with the single chamber Helmholtz self-excited oscillation pulsed jet nozzle, the erosion volume and depth increased by 14.5% and 12.6%.
With dual chamber self-excited oscillation pulsed jet nozzle as the research object, changing the structure of the second stage chamber as the variables, the inner and outer flow fields of the jet nozzle were simulated by using FLUENT. These studies are based on the theories of transient flow and underwater acoustics, and combined with the standard κ-ε model. The structural chamber of the strongest hitting power is obtained, and hitting power was compared with self-excited oscillation pulsed jet nozzle. Research results show that the nozzle has the largest hitting power with optimal cavity length, cavity diameter and downstream collision wall shape of the nozzle, and hitting power of self-excited oscillation pulsed jet nozzle is more than the single chamber 13.2%. An experiment was built to make the erosion test, erosion law of rock was analyzed, and erosion volume and depth were computed. The results show that the best structure of the nozzle is in agreement with the numerical simulation; Compared with the single chamber Helmholtz self-excited oscillation pulsed jet nozzle, the erosion volume and depth increased by 14.5% and 12.6%.
2017, 36(12): 1823-1829.
doi: 10.13433/j.cnki.1003-8728.2017.1204
Abstract:
The paper was on the background of the textured cylinder clearance seal. The average Reynolds equation was used in the micro-texture flow field for mathematical modeling. The finite difference method was used to discrete the average Reynolds equation. There are six morphologies such as hemispherical surface, cylinder, paraboloid, six-sided cube and micro-textured simulated for getting optimal micro-textured appearance. The effects of the surface roughness, surface orientation parameters and area occupancy rate on the surface friction coefficient are explored. The results show that six different morphologies can produce hydrodynamic lubrication on the surface of the piston. The hydrodynamic lubrication performance of the cylinder is the best. The rough surface asperities can form dynamic pressure bearing force during exercise. The cylindrical surface friction coefficient increases with the roughness. The micro-texture coefficient of friction decreases with the increase of surface direction parameters, area occupancy rate.
The paper was on the background of the textured cylinder clearance seal. The average Reynolds equation was used in the micro-texture flow field for mathematical modeling. The finite difference method was used to discrete the average Reynolds equation. There are six morphologies such as hemispherical surface, cylinder, paraboloid, six-sided cube and micro-textured simulated for getting optimal micro-textured appearance. The effects of the surface roughness, surface orientation parameters and area occupancy rate on the surface friction coefficient are explored. The results show that six different morphologies can produce hydrodynamic lubrication on the surface of the piston. The hydrodynamic lubrication performance of the cylinder is the best. The rough surface asperities can form dynamic pressure bearing force during exercise. The cylindrical surface friction coefficient increases with the roughness. The micro-texture coefficient of friction decreases with the increase of surface direction parameters, area occupancy rate.
2017, 36(12): 1830-1833.
doi: 10.13433/j.cnki.1003-8728.2017.1205
Abstract:
Metal-rubber is the components of the military vehicles mounting. It has the good buffering property and damping property. At first, the damping force and elastic restoring force are closely approximated on the basis of the equivalent damping theory and fourier series. Then, the linear equation of parameter on the basis of the existing mathematical model is obtained. Finally, the conclusion of the linear rigidity, cube rigidity and slip rigidity through the genetic algorithm is getten, and the trend of variation under the different excitation is also getten.
Metal-rubber is the components of the military vehicles mounting. It has the good buffering property and damping property. At first, the damping force and elastic restoring force are closely approximated on the basis of the equivalent damping theory and fourier series. Then, the linear equation of parameter on the basis of the existing mathematical model is obtained. Finally, the conclusion of the linear rigidity, cube rigidity and slip rigidity through the genetic algorithm is getten, and the trend of variation under the different excitation is also getten.
2017, 36(12): 1834-1837.
doi: 10.13433/j.cnki.1003-8728.2017.1206
Abstract:
In the non-inertial coordinate system, the dynamic equations of planar flexible beams with large overall motion and nonlinear deformation are deduced. Through the theoretic study and analysis, two kinds of coupling terms are added in the matrix of the precise model of this paper. By calculation and simulation, it is found that the effect of these two kinds of coupling causes the change of the additional stiffness and the dynamic stiffness.
In the non-inertial coordinate system, the dynamic equations of planar flexible beams with large overall motion and nonlinear deformation are deduced. Through the theoretic study and analysis, two kinds of coupling terms are added in the matrix of the precise model of this paper. By calculation and simulation, it is found that the effect of these two kinds of coupling causes the change of the additional stiffness and the dynamic stiffness.
2017, 36(12): 1838-1842.
doi: 10.13433/j.cnki.1003-8728.2017.1207
Abstract:
Based on the Dirlik method for vibration fatigue life study in the frequency domain, the finite element model is established and modified according to the model test, and the finite element method is used to predict the fatigue life of the spot welded structure. The effects of different PSD spectral types on the fatigue life under the random vibration environment are analyzed. The analysis results show that with increasing PSD amplitude under the same vibration level in the first natural frequency domain, the fatigue life under random vibration decreases. Under the influence of white noise acceleration power spectrum and when the PSD amplitude was kept unchanged; with increasing bandwidth, the fatigue life under the random vibration environment decreases. The influence of random vibration on the fatigue life in the region of non-resonance frequency between the first and second modal frequencies should not be neglected.
Based on the Dirlik method for vibration fatigue life study in the frequency domain, the finite element model is established and modified according to the model test, and the finite element method is used to predict the fatigue life of the spot welded structure. The effects of different PSD spectral types on the fatigue life under the random vibration environment are analyzed. The analysis results show that with increasing PSD amplitude under the same vibration level in the first natural frequency domain, the fatigue life under random vibration decreases. Under the influence of white noise acceleration power spectrum and when the PSD amplitude was kept unchanged; with increasing bandwidth, the fatigue life under the random vibration environment decreases. The influence of random vibration on the fatigue life in the region of non-resonance frequency between the first and second modal frequencies should not be neglected.
2017, 36(12): 1843-1851.
doi: 10.13433/j.cnki.1003-8728.2017.1208
Abstract:
As one of the most severe faults of the reciprocating machine, the abrasion fault of the connecting rod bearing shell is difficult to predict for its complex fault excitation. The multi-body dynamic model of the connecting rod bearing shell with abrasion fault was built based on the nonlinear contact model and nonlinear friction model. The deteriorating process of the fault was simulated by changing the clearance size between the crank shaft and the connecting rod bearing shell, and the changing rules of the contact force and the response characteristics of reciprocating machinery were analyzed during the process. The method for prediction and diagnosis of the fault is proposed in the research.
As one of the most severe faults of the reciprocating machine, the abrasion fault of the connecting rod bearing shell is difficult to predict for its complex fault excitation. The multi-body dynamic model of the connecting rod bearing shell with abrasion fault was built based on the nonlinear contact model and nonlinear friction model. The deteriorating process of the fault was simulated by changing the clearance size between the crank shaft and the connecting rod bearing shell, and the changing rules of the contact force and the response characteristics of reciprocating machinery were analyzed during the process. The method for prediction and diagnosis of the fault is proposed in the research.
2017, 36(12): 1852-1858.
doi: 10.13433/j.cnki.1003-8728.2017.1209
Abstract:
Crankshaft drive structure in traditional high-power three cylinder drilling pump uses a pair of meshing herringbone gears to transmit power. As the gear is located at one end of the crankshaft, the stresses and deformation of the crankshaft are the biggest when the other end of the two cranks are stressed. In order to alleviate this situation, the crankshaft drive structure of some high-power drilling pump uses two pairs of meshing helical gears to transmit power. For this kind of crankshaft drive structure, the formulas of two gears meshing force, bearing reaction force and torque and bending moment at the cross-section mutation are deduced. The strength of the crankshaft was checked, and the strength analysis via finite element method was done by using workbench ANSYS. The analysis results show that the maximum stresses on the most dangerous section on both sides of the middle crank of the transmission crankshaft with double side helical gear are reduced by 21.3% and 11.5% respectively comparing with the traditional transmission crankshaft. And the maximum deformation is of 45.3% lower than that of the traditional transmission crankshaft, the strength and stiffness are improved. At the same time, it can improve the strength of crankshaft by appropriately increasing the fillet value of the crankshaft.
Crankshaft drive structure in traditional high-power three cylinder drilling pump uses a pair of meshing herringbone gears to transmit power. As the gear is located at one end of the crankshaft, the stresses and deformation of the crankshaft are the biggest when the other end of the two cranks are stressed. In order to alleviate this situation, the crankshaft drive structure of some high-power drilling pump uses two pairs of meshing helical gears to transmit power. For this kind of crankshaft drive structure, the formulas of two gears meshing force, bearing reaction force and torque and bending moment at the cross-section mutation are deduced. The strength of the crankshaft was checked, and the strength analysis via finite element method was done by using workbench ANSYS. The analysis results show that the maximum stresses on the most dangerous section on both sides of the middle crank of the transmission crankshaft with double side helical gear are reduced by 21.3% and 11.5% respectively comparing with the traditional transmission crankshaft. And the maximum deformation is of 45.3% lower than that of the traditional transmission crankshaft, the strength and stiffness are improved. At the same time, it can improve the strength of crankshaft by appropriately increasing the fillet value of the crankshaft.
2017, 36(12): 1859-1865.
doi: 10.13433/j.cnki.1003-8728.2017.1210
Abstract:
In order to overcome the deficiencies of low accuracy and robustness for traditional PID controller in the trajectory tracking problem of quad-rotor unmanned aerial vehicles, a sliding mode PID algorithm is proposed. The dynamic model is established based on Euler-Poincare equation, and a sliding mode PID trajectory tracking controller is designed. The proposed algorithm with PID sliding surface provides a faster response and a higher anti-jamming ability than that of the traditional PID. Simulation is performed under different conditions by using MATLAB/Simulink. By compared with traditional PID controller the results show that the sliding mode PID controller has a better trajectory tracking performance, and it has faster response, smaller overshoot and stronger robustness, which verifies the effectiveness of the proposed algorithm.
In order to overcome the deficiencies of low accuracy and robustness for traditional PID controller in the trajectory tracking problem of quad-rotor unmanned aerial vehicles, a sliding mode PID algorithm is proposed. The dynamic model is established based on Euler-Poincare equation, and a sliding mode PID trajectory tracking controller is designed. The proposed algorithm with PID sliding surface provides a faster response and a higher anti-jamming ability than that of the traditional PID. Simulation is performed under different conditions by using MATLAB/Simulink. By compared with traditional PID controller the results show that the sliding mode PID controller has a better trajectory tracking performance, and it has faster response, smaller overshoot and stronger robustness, which verifies the effectiveness of the proposed algorithm.
2017, 36(12): 1866-1872.
doi: 10.13433/j.cnki.1003-8728.2017.1211
Abstract:
The typical 3-RRR planar parallel mechanism has two translations and one rotation and thus is a kind of extensively applied plane location and transfer equipment. Firstly, the coupling degree of the parallel mechanism is calculated to be k=1. Then, based on the structural coupling reduction principle, this paper designs its coupling reduction mechanism with zero coupling degree, which not only leads to its easy analytic direct kinematic solution but also makes the input and output of the moving platform partially motion-decoupling. Moreover, the workspace and singularity of this coupling reduction mechanism are also performed. Finally, the comprehensive comparison of two types of the coupling reduction mechanism shows that the main performance of the structural coupling reduction mechanism is better than that of the original mechanism, indicating that the structural coupling reduction mechanism is an effective method for optimizing the topological structure.
The typical 3-RRR planar parallel mechanism has two translations and one rotation and thus is a kind of extensively applied plane location and transfer equipment. Firstly, the coupling degree of the parallel mechanism is calculated to be k=1. Then, based on the structural coupling reduction principle, this paper designs its coupling reduction mechanism with zero coupling degree, which not only leads to its easy analytic direct kinematic solution but also makes the input and output of the moving platform partially motion-decoupling. Moreover, the workspace and singularity of this coupling reduction mechanism are also performed. Finally, the comprehensive comparison of two types of the coupling reduction mechanism shows that the main performance of the structural coupling reduction mechanism is better than that of the original mechanism, indicating that the structural coupling reduction mechanism is an effective method for optimizing the topological structure.
2017, 36(12): 1873-1876.
doi: 10.13433/j.cnki.1003-8728.2017.1212
Abstract:
A new analysis method combined order tracking with Hilbert envelope demodulation is proposed to fault diagnosis of the wind turbine transmission chain, which is non-stationary and demodulating. Using the order tracking, sampling vibration signals in time domain are resampled in the angle domain, so that the non-stationary signal in time domain was converted into stationary signal in angle domain. It can overcome effectively the "frequency smear" phenomenon, which cannot be solved with the traditional frequency spectrum method. Then, the Hilbert envelope demodulation was used to demodulate the low frequency fault signal from the high frequency carrier signal.
A new analysis method combined order tracking with Hilbert envelope demodulation is proposed to fault diagnosis of the wind turbine transmission chain, which is non-stationary and demodulating. Using the order tracking, sampling vibration signals in time domain are resampled in the angle domain, so that the non-stationary signal in time domain was converted into stationary signal in angle domain. It can overcome effectively the "frequency smear" phenomenon, which cannot be solved with the traditional frequency spectrum method. Then, the Hilbert envelope demodulation was used to demodulate the low frequency fault signal from the high frequency carrier signal.
2017, 36(12): 1877-1884.
doi: 10.13433/j.cnki.1003-8728.2017.1213
Abstract:
In the view of the problems, the poor quality of machined surface and inconsistent machining precision of left and right tooth surfaces, the design and computation method of slicing cutter with equal rake angle is proposed. On beginning, the conjugate surface of gear surface is obtained based on the principle of conjugate surface according to the geometric feature of machining gear tooth surface and the motion relationship in slicing. Meanwhile, the sphere surface is chosen as the original rake face. To achieve the requirement of theoretical error-free edge profile, the intersecting curve of conjugate surface and original design rake face is calculated as the cutting edge. On the basis of those works, the original rake face is redesigned by constructing a new rake face along the cutting edge complying with the principle of consistent rake angle. With this method, a series of cutting edges with theoretical error-free edge profile are obtained by means of the simulative cutter sharpening, which are used for constructing the flank face. As a result, the complete slicing cutter with equal rake angle is obtained. The calculation case is performed to verify the feasibility and effectiveness of the above developed method. At last, the conclusion and discussion are provided.
In the view of the problems, the poor quality of machined surface and inconsistent machining precision of left and right tooth surfaces, the design and computation method of slicing cutter with equal rake angle is proposed. On beginning, the conjugate surface of gear surface is obtained based on the principle of conjugate surface according to the geometric feature of machining gear tooth surface and the motion relationship in slicing. Meanwhile, the sphere surface is chosen as the original rake face. To achieve the requirement of theoretical error-free edge profile, the intersecting curve of conjugate surface and original design rake face is calculated as the cutting edge. On the basis of those works, the original rake face is redesigned by constructing a new rake face along the cutting edge complying with the principle of consistent rake angle. With this method, a series of cutting edges with theoretical error-free edge profile are obtained by means of the simulative cutter sharpening, which are used for constructing the flank face. As a result, the complete slicing cutter with equal rake angle is obtained. The calculation case is performed to verify the feasibility and effectiveness of the above developed method. At last, the conclusion and discussion are provided.
2017, 36(12): 1885-1890.
doi: 10.13433/j.cnki.1003-8728.2017.1214
Abstract:
Due to the diversity of contact characteristics between the elastic abrasives and the workpiece surface in the precision grinding operations, the irregular wear appears on the abrasives, followed by poor effects and a high rejection rate. Aiming at the relationship between the processing efficiency and the contact characteristics in theory, a mathematical model for predicting the optimal parameter combination for grinding is conducted based on the Hertz theory. Firstly, taking steel M300 as the study objective,the model for residual peak is established by analyzing the micro contact characteristics of the elastic ball-end abrasives. Secondly, the functional relationship between the residual peak removal area and the main parameters affecting the grinding accuracy is derived. Lastly, the influence degree of the each parameter on the polishing effect and the best parameter combination are gotten with the Taguchi method, and which are verified by a set of experiments.
Due to the diversity of contact characteristics between the elastic abrasives and the workpiece surface in the precision grinding operations, the irregular wear appears on the abrasives, followed by poor effects and a high rejection rate. Aiming at the relationship between the processing efficiency and the contact characteristics in theory, a mathematical model for predicting the optimal parameter combination for grinding is conducted based on the Hertz theory. Firstly, taking steel M300 as the study objective,the model for residual peak is established by analyzing the micro contact characteristics of the elastic ball-end abrasives. Secondly, the functional relationship between the residual peak removal area and the main parameters affecting the grinding accuracy is derived. Lastly, the influence degree of the each parameter on the polishing effect and the best parameter combination are gotten with the Taguchi method, and which are verified by a set of experiments.
2017, 36(12): 1891-1895.
doi: 10.13433/j.cnki.1003-8728.2017.1215
Abstract:
In order to manufacture the micro-structure of metal with high efficiency and precision, based on the micro-electrochemical machining principle, a new method of gas film shielding electrochemical micro-machining was presented. The distribution of gas bubbles, the influence of gas film on the hydraulic jump and the micro-concave shape machined with the gas film shielding electrochemical micro-machining method were analyzed. The analysis results show that the gas film shielding micro-electrochemical machining method can reduce the surface roughness by 29.4%, increase the depth to diameter ratio by 85%, and reduce the stray corrosion, compared with the electrochemical jet machining method under the condition that the parameters are the same, verifying that the new method is superior.
In order to manufacture the micro-structure of metal with high efficiency and precision, based on the micro-electrochemical machining principle, a new method of gas film shielding electrochemical micro-machining was presented. The distribution of gas bubbles, the influence of gas film on the hydraulic jump and the micro-concave shape machined with the gas film shielding electrochemical micro-machining method were analyzed. The analysis results show that the gas film shielding micro-electrochemical machining method can reduce the surface roughness by 29.4%, increase the depth to diameter ratio by 85%, and reduce the stray corrosion, compared with the electrochemical jet machining method under the condition that the parameters are the same, verifying that the new method is superior.
2017, 36(12): 1896-1905.
doi: 10.13433/j.cnki.1003-8728.2017.1216
Abstract:
The 45° pyramidal shape is taken as the research object, the Design-Export 8.0 software of mathematical statistics via responses surface methodology(RSM) was utilized to analyze the forming parameters in SPIF. The Box-Behnken Design (BBD) experimental methods are carried out. Four factors and three levels experimental scheme is designed. The tool head diameter D, step increment Z, feed rate F and spindle speed S are the factors that influence the surface roughness in SPIF. The response models for longitudinal surface roughness and transverse surface roughness in SPIF were established respectively. The constrains of actual forming conditions upon the forming parameters are further analyzed. With the longitudinal and transverse surface roughness overall optimal, the goal of improving the forming quality of surface in SPIF, the optimization models for forming parameters were established. The genetic algorithm program is designed and the optimization problem is solved via Matlab genetic algorithm toolbox. The experiment results show that the algorithm could achieve the optimized forming parameters which satisfy multi-constraint conditions effectively and rapidly.
The 45° pyramidal shape is taken as the research object, the Design-Export 8.0 software of mathematical statistics via responses surface methodology(RSM) was utilized to analyze the forming parameters in SPIF. The Box-Behnken Design (BBD) experimental methods are carried out. Four factors and three levels experimental scheme is designed. The tool head diameter D, step increment Z, feed rate F and spindle speed S are the factors that influence the surface roughness in SPIF. The response models for longitudinal surface roughness and transverse surface roughness in SPIF were established respectively. The constrains of actual forming conditions upon the forming parameters are further analyzed. With the longitudinal and transverse surface roughness overall optimal, the goal of improving the forming quality of surface in SPIF, the optimization models for forming parameters were established. The genetic algorithm program is designed and the optimization problem is solved via Matlab genetic algorithm toolbox. The experiment results show that the algorithm could achieve the optimized forming parameters which satisfy multi-constraint conditions effectively and rapidly.
2017, 36(12): 1906-1913.
doi: 10.13433/j.cnki.1003-8728.2017.1217
Abstract:
In order to solve the multi-objective optimization problem of cutting insert geometric parameters and avoid the unsatisfactory processing effect in turning, an optimization decision method based on entropy-weight Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was proposed. By using TOPSIS model and finite element method, and considering the results such as wear depth, cutting force, tool-chip interface temperature and tool-chip interface pressure, the controllable factors of cutting insert shapes, relief angle, nose radius were planned for orthogonal experiment design, and the objective values were received by numerical analysis. Due to the determination of entropy weight coefficient, a weighted normalized matrix of multi-objective optimization was built. The distance between experiment design sequence and ideal solution was calculated to get relative approach degrees, and the existing schemes were ordered. According to the effects of each factor on the results, the optimal geometry parameter combination was determined. On this basis, the geometric parameters of cemented carbide inserts are provided by engineering practice and the results shows that the proposed method is valid and feasible.
In order to solve the multi-objective optimization problem of cutting insert geometric parameters and avoid the unsatisfactory processing effect in turning, an optimization decision method based on entropy-weight Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was proposed. By using TOPSIS model and finite element method, and considering the results such as wear depth, cutting force, tool-chip interface temperature and tool-chip interface pressure, the controllable factors of cutting insert shapes, relief angle, nose radius were planned for orthogonal experiment design, and the objective values were received by numerical analysis. Due to the determination of entropy weight coefficient, a weighted normalized matrix of multi-objective optimization was built. The distance between experiment design sequence and ideal solution was calculated to get relative approach degrees, and the existing schemes were ordered. According to the effects of each factor on the results, the optimal geometry parameter combination was determined. On this basis, the geometric parameters of cemented carbide inserts are provided by engineering practice and the results shows that the proposed method is valid and feasible.
2017, 36(12): 1914-1920.
doi: 10.13433/j.cnki.1003-8728.2017.1218
Abstract:
The taguchi's orthogonal array is adopted in cutting steel plate (06Cr19Ni10) experiment by abrasive water jet, then the cross-sectional surface roughness is used to evaluate the standard of surface quality for workpiece. Jet pressure, traverse speed, standoff distance, abrasive grit size and abrasive flow rate were carried as processing parameter variables. A prediction model for surface roughness by using regression analysis is established, and the processing parameters via response surface analysis method to obtain a corresponding parameter value to the minimum surface roughness are optimized. After that, the minimum surface roughness predicted value was obtained, and the experimental learning sample data was trained by using artificial neural network. the optimization of processing parameters was taken respectively via artificial intelligent algorithms (genetic pattern search and simulated annealing), and then the integration of artificial neural network-genetic pattern search-simulated annealing technique to further optimize the processing parameters to obtain the optimum parameter values corresponding minimum surface roughness was accepted. The results show that the integration of technology, compared with single genetic pattern search or simulated annealing method, greatly reduces the surface roughness value and shortens the optimization time.
The taguchi's orthogonal array is adopted in cutting steel plate (06Cr19Ni10) experiment by abrasive water jet, then the cross-sectional surface roughness is used to evaluate the standard of surface quality for workpiece. Jet pressure, traverse speed, standoff distance, abrasive grit size and abrasive flow rate were carried as processing parameter variables. A prediction model for surface roughness by using regression analysis is established, and the processing parameters via response surface analysis method to obtain a corresponding parameter value to the minimum surface roughness are optimized. After that, the minimum surface roughness predicted value was obtained, and the experimental learning sample data was trained by using artificial neural network. the optimization of processing parameters was taken respectively via artificial intelligent algorithms (genetic pattern search and simulated annealing), and then the integration of artificial neural network-genetic pattern search-simulated annealing technique to further optimize the processing parameters to obtain the optimum parameter values corresponding minimum surface roughness was accepted. The results show that the integration of technology, compared with single genetic pattern search or simulated annealing method, greatly reduces the surface roughness value and shortens the optimization time.
2017, 36(12): 1921-1925.
doi: 10.13433/j.cnki.1003-8728.2017.1219
Abstract:
Purpose of this paper is to design a low cost, high efficiency medium frequency induction heater. The 2D model of the vertical GaN-MOCVD reactor with induction heating was performed by the finite element method. The structural analysis of the copper coils on temperature uniformity on the surface of graphite was researched; then thermal-electromagnetic coupling analysis reveals that lessening the change can increase efficiency of heat conduction. The structural design of the induction heater is optimized based on the analysis results,and the prototype of heater is designed and fabricated. Finally, it verifies temperature distribution on the surface of graphite floating in 0.2% by experiments and the uniform temperature distribution is good, meeting the production requirement.
Purpose of this paper is to design a low cost, high efficiency medium frequency induction heater. The 2D model of the vertical GaN-MOCVD reactor with induction heating was performed by the finite element method. The structural analysis of the copper coils on temperature uniformity on the surface of graphite was researched; then thermal-electromagnetic coupling analysis reveals that lessening the change can increase efficiency of heat conduction. The structural design of the induction heater is optimized based on the analysis results,and the prototype of heater is designed and fabricated. Finally, it verifies temperature distribution on the surface of graphite floating in 0.2% by experiments and the uniform temperature distribution is good, meeting the production requirement.
2017, 36(12): 1926-1934.
doi: 10.13433/j.cnki.1003-8728.2017.1220
Abstract:
In order to simplify the calibration process of a robot's monocular vision and laser ranging location system, a rapid calibration method is proposed for a robot's location system. The calibration of camera parameters, camera distortion parameters and eye-hand relation is performed with only one calibration experiment, and the laser ranging sensor is calibrated through the eye-hand relation.Besides, to improve the validity of calibration and location, a pose correction method for the robot's location system based on the laser ranging sensor is proposed; then a pose correction model is established to solve the pose correction angle, and the depth direction measurement error is compensated with the pose correction method. The experimental results prove that the calibration and pose correction method proposed in the paper is simple, correct and reliable, meeting the requirements for the location precision of a robot's de-mold system.
In order to simplify the calibration process of a robot's monocular vision and laser ranging location system, a rapid calibration method is proposed for a robot's location system. The calibration of camera parameters, camera distortion parameters and eye-hand relation is performed with only one calibration experiment, and the laser ranging sensor is calibrated through the eye-hand relation.Besides, to improve the validity of calibration and location, a pose correction method for the robot's location system based on the laser ranging sensor is proposed; then a pose correction model is established to solve the pose correction angle, and the depth direction measurement error is compensated with the pose correction method. The experimental results prove that the calibration and pose correction method proposed in the paper is simple, correct and reliable, meeting the requirements for the location precision of a robot's de-mold system.
2017, 36(12): 1935-1940.
doi: 10.13433/j.cnki.1003-8728.2017.1221
Abstract:
Switchable engine mounts (SEM) play a significant role in the design of High-intermediate level sedans and SUVs. Two kinds of switchable engine mounts with orifice tunable and decoupled stiffness variable, respectively, are introduced in this paper. Lumped parameter models are developed and their key parameters are identified by experiment and genetic algorithm. The dynamic characteristics of both on/off modes are simulated and tested for each mount, agreement between the results of the two methods is achieved. Finally, the sensitivity of parameters was analyzed. The present work can provide some reference for the design,improvement and optimization of SEM.
Switchable engine mounts (SEM) play a significant role in the design of High-intermediate level sedans and SUVs. Two kinds of switchable engine mounts with orifice tunable and decoupled stiffness variable, respectively, are introduced in this paper. Lumped parameter models are developed and their key parameters are identified by experiment and genetic algorithm. The dynamic characteristics of both on/off modes are simulated and tested for each mount, agreement between the results of the two methods is achieved. Finally, the sensitivity of parameters was analyzed. The present work can provide some reference for the design,improvement and optimization of SEM.
2017, 36(12): 1941-1948.
doi: 10.13433/j.cnki.1003-8728.2017.1222
Abstract:
As the compressed natural gas (CNG) engine moves toward the direction of high speed and high power development, the piston pin hole stress is greater, causing fatigue crack on the piston pin hole. Therefore, we design the new structure of an arc surface bush piston pin hole. Such piston bush is derived from the movement analysis and assembly conditions analysis. The stress distribution state of the piston under different load conditions of mechanical load and thermo-mechanical coupling load were analyzed with the finite element method. Simulation results show that the Mises stress of the new structured piston bush decreases by 25.3%, that the Mises stress of the new structured piston pin hole decreases by 27.9% compared with the original structured piston and that its contact stress decreases by 35.4% under the mechanical load. The analysis results on the piston stress state of the thermo-mechanical coupled load are similar to those on the mechanical load. In addition, the piston's stress state has been greatly improved. The stress distribution of the piston pin hole with an arc surface bush is more homogeneous; it is easier to form oil film on the arc surface bush. Therefore, the new structure of the piston pin hole with arc surface bush has strong capability of decreasing stress and increasing the lubricity and anti-wear ability.
As the compressed natural gas (CNG) engine moves toward the direction of high speed and high power development, the piston pin hole stress is greater, causing fatigue crack on the piston pin hole. Therefore, we design the new structure of an arc surface bush piston pin hole. Such piston bush is derived from the movement analysis and assembly conditions analysis. The stress distribution state of the piston under different load conditions of mechanical load and thermo-mechanical coupling load were analyzed with the finite element method. Simulation results show that the Mises stress of the new structured piston bush decreases by 25.3%, that the Mises stress of the new structured piston pin hole decreases by 27.9% compared with the original structured piston and that its contact stress decreases by 35.4% under the mechanical load. The analysis results on the piston stress state of the thermo-mechanical coupled load are similar to those on the mechanical load. In addition, the piston's stress state has been greatly improved. The stress distribution of the piston pin hole with an arc surface bush is more homogeneous; it is easier to form oil film on the arc surface bush. Therefore, the new structure of the piston pin hole with arc surface bush has strong capability of decreasing stress and increasing the lubricity and anti-wear ability.
2017, 36(12): 1949-1955.
doi: 10.13433/j.cnki.1003-8728.2017.1223
Abstract:
In order to improve vehicle ride comfort performance and reduce the tire dynamic load, the 2-DOF dynamic model of semi-active suspension system with sky-hook damping was established. Then the fractional calculus theory was applied to the semi-active suspension, and an Oustaloup digital filter algorithm was used to simulate the fractional calculus. Then the optimal parameters of the fractional order sky-hook damping controller were solved by using genetic algorithm. Finally, the simulation model of semi-active suspension with fractional order sky-hook damping control was built and analyzed in time and frequency domain. The simulation results indicate that the semi-active suspension of fractional order sky-hook damping controller can suppress resonance effectively.
In order to improve vehicle ride comfort performance and reduce the tire dynamic load, the 2-DOF dynamic model of semi-active suspension system with sky-hook damping was established. Then the fractional calculus theory was applied to the semi-active suspension, and an Oustaloup digital filter algorithm was used to simulate the fractional calculus. Then the optimal parameters of the fractional order sky-hook damping controller were solved by using genetic algorithm. Finally, the simulation model of semi-active suspension with fractional order sky-hook damping control was built and analyzed in time and frequency domain. The simulation results indicate that the semi-active suspension of fractional order sky-hook damping controller can suppress resonance effectively.
2017, 36(12): 1956-1963.
doi: 10.13433/j.cnki.1003-8728.2017.1224
Abstract:
On the basis of the seal coating elastic modulus experiemnts, the model for seal coating friction via finite element method was established, and the analysis on the stress distribution of AL/BN abradable sealing coating used in aeroengine was carried out. The influence of the friction coefficient, coating thickness and bonding layer thickness on the coating/bonding layer/substrate system was analyzed. The results show that under the tangential load, the peak stress on the coating surface, the interface of coating and bonding layer and the interface of bonding layer and substrate increase with the increasing of friction coefficient. The Peak stress on the coating surface and two interfaces decrease with the increasing of coating thickness. But when the thickness of coating reaches a certain degree, to increase the thickness of coating can't effectively decrease the peak stress. The thickness of bonding layer has small effect on the variation of stress on the coating surface and the interface of coating and bonding layer. But with the decreasing of bonding layer thickness, the stress peak on the interface of bonding layer and substrate increase.
On the basis of the seal coating elastic modulus experiemnts, the model for seal coating friction via finite element method was established, and the analysis on the stress distribution of AL/BN abradable sealing coating used in aeroengine was carried out. The influence of the friction coefficient, coating thickness and bonding layer thickness on the coating/bonding layer/substrate system was analyzed. The results show that under the tangential load, the peak stress on the coating surface, the interface of coating and bonding layer and the interface of bonding layer and substrate increase with the increasing of friction coefficient. The Peak stress on the coating surface and two interfaces decrease with the increasing of coating thickness. But when the thickness of coating reaches a certain degree, to increase the thickness of coating can't effectively decrease the peak stress. The thickness of bonding layer has small effect on the variation of stress on the coating surface and the interface of coating and bonding layer. But with the decreasing of bonding layer thickness, the stress peak on the interface of bonding layer and substrate increase.
2017, 36(12): 1964-1969.
doi: 10.13433/j.cnki.1003-8728.2017.1225
Abstract:
Since the aircraft engine casing is a non-continuous structure, which will affect the aircraft engine casing vibration characteristics. In the study of the vibration characteristics of the conventional stator box components, the bolt connection structure of the casing installation side is often neglected, resulting in a large deviation in the vibration simulation results. In this study, the finite element analysis model of bolted connection structure is established based on the finite element method. The influence of bolt preload, bolt distribution and bolt number on the bending stiffness and vibration frequency of the casing is studied. The results show that, due to the presence of the bolted connection structure, the structural rigidity of the casing is reduced. The bolt pretension, distribution and the number of bolts are the main factors that affect the bending stiffness and vibration frequency of an aero-engine case.
Since the aircraft engine casing is a non-continuous structure, which will affect the aircraft engine casing vibration characteristics. In the study of the vibration characteristics of the conventional stator box components, the bolt connection structure of the casing installation side is often neglected, resulting in a large deviation in the vibration simulation results. In this study, the finite element analysis model of bolted connection structure is established based on the finite element method. The influence of bolt preload, bolt distribution and bolt number on the bending stiffness and vibration frequency of the casing is studied. The results show that, due to the presence of the bolted connection structure, the structural rigidity of the casing is reduced. The bolt pretension, distribution and the number of bolts are the main factors that affect the bending stiffness and vibration frequency of an aero-engine case.
2017, 36(12): 1970-1974.
doi: 10.13433/j.cnki.1003-8728.2017.1226
Abstract:
Z-layout pipelines used to connect two parallel pipe-joints numerously exist in aircraft hydraulic piping system. Different layout pipelines have different modal characteristics. The design of Z-layout pipelines is determined by two parameters:the location of the elbow and the radius of curvature. The effects of these two design parameters on the modal characteristics of pipeline are studied by experiments and the numerical simulations. Results indicate that the first mode appears in the direction perpendicular to the layout plane and the second mode appears in the layout plane of the Z-layout pipelines. The first natural frequency increases while the second natural frequency decreases when the location of the elbow changes from one end to the mid-point between the two joints and the natural frequencies increase with the increasing of radius of the elbow.
Z-layout pipelines used to connect two parallel pipe-joints numerously exist in aircraft hydraulic piping system. Different layout pipelines have different modal characteristics. The design of Z-layout pipelines is determined by two parameters:the location of the elbow and the radius of curvature. The effects of these two design parameters on the modal characteristics of pipeline are studied by experiments and the numerical simulations. Results indicate that the first mode appears in the direction perpendicular to the layout plane and the second mode appears in the layout plane of the Z-layout pipelines. The first natural frequency increases while the second natural frequency decreases when the location of the elbow changes from one end to the mid-point between the two joints and the natural frequencies increase with the increasing of radius of the elbow.
