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RSS2015 Vol. 34, No. 5
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2015, 34(5): 657-661.
doi: 10.13433/j.cnki.1003-8728.2015.0501
PDF 1277KB
Abstract:
Based on the some hydraulic top-hammer drill, its luffing mechanism was introduced. The coordination was set with D-H method. With proper calculation and analysis, its kinematics equations were created, after which, those equations were verified by some specific position of the luffing mechanism. With MATLAB software, reachable space, effective space and effective working scale were got and compared with 3D-scatter-views. The analysis method of kinematicswas systematically advanced, which laid on the basis of the dynamics and motion control of hydraulic top-hammer drill luffing mechanism.
Based on the some hydraulic top-hammer drill, its luffing mechanism was introduced. The coordination was set with D-H method. With proper calculation and analysis, its kinematics equations were created, after which, those equations were verified by some specific position of the luffing mechanism. With MATLAB software, reachable space, effective space and effective working scale were got and compared with 3D-scatter-views. The analysis method of kinematicswas systematically advanced, which laid on the basis of the dynamics and motion control of hydraulic top-hammer drill luffing mechanism.
2015, 34(5): 662-667.
doi: 10.13433/j.cnki.1003-8728.2015.0502
Abstract:
Based on the analysis of the working characteristics and requirements of the jack-up and sliding equipment, the structural design of the jack-up system is studied, and the structure of each major components and design parameters are determined. The simplified 3D geometry model for the equipment is imported into ANSYS Workbench, the stress and the strain of the relevant parts are analyzed in the working state based on the results of the analysis. Then, the optimal design was done to the corresponding components of equipment. Finally, a set of models that has a reasonable structure design and the strength and stiffness can meet the design requirements is set up.
Based on the analysis of the working characteristics and requirements of the jack-up and sliding equipment, the structural design of the jack-up system is studied, and the structure of each major components and design parameters are determined. The simplified 3D geometry model for the equipment is imported into ANSYS Workbench, the stress and the strain of the relevant parts are analyzed in the working state based on the results of the analysis. Then, the optimal design was done to the corresponding components of equipment. Finally, a set of models that has a reasonable structure design and the strength and stiffness can meet the design requirements is set up.
A Research on Upper Limb Posture Evaluation Based on Fatigue Characteristics in Narrow Working Cabin
2015, 34(5): 668-673.
doi: 10.13433/j.cnki.1003-8728.2015.0503
Abstract:
According to the characteristics of narrow working cabin that is small space, long hours and light load, we suggest a method of upper limb posture assessment based on fatigue characteristics. Using fatigue characteristics of upper limb obtained from experiments, we build the parameter sport model of human body, and establish an idea for the resolution of this type of question with the finger space coordinate transformation. The fatigue characteristic value of the different position in the global coordinate system is obtained. Finally, a physiological parameters definition of human upper limb posture is achieved. The feasibility of the algorithm is revealed by a simulation measurement of the staff posture inside the manned submersible. The upper limb posture evolution can be a reference for the control efficiency of design and work space layout. It also provides a reliable evaluation method of working postures in the narrow working cabin.
According to the characteristics of narrow working cabin that is small space, long hours and light load, we suggest a method of upper limb posture assessment based on fatigue characteristics. Using fatigue characteristics of upper limb obtained from experiments, we build the parameter sport model of human body, and establish an idea for the resolution of this type of question with the finger space coordinate transformation. The fatigue characteristic value of the different position in the global coordinate system is obtained. Finally, a physiological parameters definition of human upper limb posture is achieved. The feasibility of the algorithm is revealed by a simulation measurement of the staff posture inside the manned submersible. The upper limb posture evolution can be a reference for the control efficiency of design and work space layout. It also provides a reliable evaluation method of working postures in the narrow working cabin.
2015, 34(5): 674-677.
doi: 10.13433/j.cnki.1003-8728.2015.0504
Abstract:
According to infinitesimal method, we establish the wave equation of conical ultrasonic horn. Base on the method of separation of variables and boundary conditions, the conical ultrasonic horn amplification coefficient, which is the mathematical expression of three variables called diameter ratio, length and stimulus frequency, is solved. In order to research the relationship of amplification coefficient and diameter ratio, length, external induced frequency, set successively two of the three variables as constant, then we solve amplification coefficient according to the third variable sampling values. The numerical example of ultrasonic horn is applied to get curve fitting by Matlab. Analyse qualitatively cone-shaped ultrasonic horn amplification factor relationship with its ratio of diameter, length, external induced frequency.
According to infinitesimal method, we establish the wave equation of conical ultrasonic horn. Base on the method of separation of variables and boundary conditions, the conical ultrasonic horn amplification coefficient, which is the mathematical expression of three variables called diameter ratio, length and stimulus frequency, is solved. In order to research the relationship of amplification coefficient and diameter ratio, length, external induced frequency, set successively two of the three variables as constant, then we solve amplification coefficient according to the third variable sampling values. The numerical example of ultrasonic horn is applied to get curve fitting by Matlab. Analyse qualitatively cone-shaped ultrasonic horn amplification factor relationship with its ratio of diameter, length, external induced frequency.
2015, 34(5): 678-682.
doi: 10.13433/j.cnki.1003-8728.2015.0505
Abstract:
According to the principle of one dimensional flow, we present a new method named isosceles trapezoid design method to get 3D the acceptable meridional profile in 9 steps. Comparing both meridional profiles designed respectly with the proposed method and with Vista RTD, we obtain the error to be about 5%. And the analysing results obtained with CFX show that there is no obvious difference between the aerodynamic performances of the two models. Finally the conclusion can be drawn that the isosceles trapezoid design method is feasible for designing the meridional profile on impeller.
According to the principle of one dimensional flow, we present a new method named isosceles trapezoid design method to get 3D the acceptable meridional profile in 9 steps. Comparing both meridional profiles designed respectly with the proposed method and with Vista RTD, we obtain the error to be about 5%. And the analysing results obtained with CFX show that there is no obvious difference between the aerodynamic performances of the two models. Finally the conclusion can be drawn that the isosceles trapezoid design method is feasible for designing the meridional profile on impeller.
2015, 34(5): 683-687.
doi: 10.13433/j.cnki.1003-8728.2015.0506
Abstract:
Aiming at the vibration problem for mechanical systems such as feed driving system in machine tools, cranes and material handling systems, which are widely used in industrial applications, we propose an S-shaped curve trajectory generation method to achieve residual vibration suppression. A simple dynamic model of a mechanical system including vibration properties is given. The necessary and sufficient conditions for an S-shaped curve trajectory to suppress the residual vibration are analytically obtained, and numerical simulations demonstrate the effectiveness of the proposed conditions. This conditions are applied to an overhead crane system to demonstrate the validity of the conditions by experimental results. The S-shaped trajectory may be applied to conventional industrial controllers to achieve better cost efficiency.
Aiming at the vibration problem for mechanical systems such as feed driving system in machine tools, cranes and material handling systems, which are widely used in industrial applications, we propose an S-shaped curve trajectory generation method to achieve residual vibration suppression. A simple dynamic model of a mechanical system including vibration properties is given. The necessary and sufficient conditions for an S-shaped curve trajectory to suppress the residual vibration are analytically obtained, and numerical simulations demonstrate the effectiveness of the proposed conditions. This conditions are applied to an overhead crane system to demonstrate the validity of the conditions by experimental results. The S-shaped trajectory may be applied to conventional industrial controllers to achieve better cost efficiency.
2015, 34(5): 688-693.
doi: 10.13433/j.cnki.1003-8728.2015.0507
Abstract:
Performance of hydrostatic bearing plays a decisive influence on dynamic performance of spindle rotor device in high-precision planar grinding machining. Based on the electric spindle rotor device of a high-precision planar grinding machining, the finite element model of electric spindle device is established, finding out how the hydrostatic bearing stiffness and damping values affect the natural frequencies, dynamic stiffness and critical speed of electric spindle rotor device. When the stiffness of front and rear hydrostatic bearings is the same, the natural frequencies of electric spindle rotor device have positively change relationships with the hydrostatic bearing stiffness and bearing damping; the dynamic stiffness has positively change relationships with the bearing stiffness and negative change relationships with the bearing damping; the critical speed has positively change relationships with the bearing stiffness. When the bearing stiffness is greater than 3×105 N/mm, the bearing damping has little impact on the critical speed, at this point increasing the bearing damping value can improve the natural frequencies and dynamic stiffness, reduce vibration amplitude, achieving good dynamic performance. When the stiffness of front and rear hydrostatic bearing is different, the impact of bearing stiffness fluctuations on the minimum dynamic stiffness of the device is gentler compared with when bearing stiffness are the same, consequently the influence on the machining accuracy is more stable.
Performance of hydrostatic bearing plays a decisive influence on dynamic performance of spindle rotor device in high-precision planar grinding machining. Based on the electric spindle rotor device of a high-precision planar grinding machining, the finite element model of electric spindle device is established, finding out how the hydrostatic bearing stiffness and damping values affect the natural frequencies, dynamic stiffness and critical speed of electric spindle rotor device. When the stiffness of front and rear hydrostatic bearings is the same, the natural frequencies of electric spindle rotor device have positively change relationships with the hydrostatic bearing stiffness and bearing damping; the dynamic stiffness has positively change relationships with the bearing stiffness and negative change relationships with the bearing damping; the critical speed has positively change relationships with the bearing stiffness. When the bearing stiffness is greater than 3×105 N/mm, the bearing damping has little impact on the critical speed, at this point increasing the bearing damping value can improve the natural frequencies and dynamic stiffness, reduce vibration amplitude, achieving good dynamic performance. When the stiffness of front and rear hydrostatic bearing is different, the impact of bearing stiffness fluctuations on the minimum dynamic stiffness of the device is gentler compared with when bearing stiffness are the same, consequently the influence on the machining accuracy is more stable.
2015, 34(5): 694-698.
doi: 10.13433/j.cnki.1003-8728.2015.0508
Abstract:
Analyzing the working principles and internal compression processes of an oil-gas multiphase pump, its theoretical calculation formulas is deduced, its input power P, its additional input power Ps and the input power Pt of external compression pump. With an actual example, the changes in P, Ps/P and (Pt -P)/Pt of pumps are summarized under the internal compression ratio λ (by changing the suction pressure p1 and the discharge pressure pd) and the gas-liquid ratio τ. When λ is constant, P decreases, Ps/P and (Pt-P)/Pt increase with τ increasing. If λ changes, the relationship between P and λ is more complicated; Ps/P always decreases with λ increasing and (Pt-P)/Pt behaves in an opposite way. P changes faster when p1 changes in relation to the changing pd; Ps/P behaves in an opposite way; (Pt-P)/Pt has little change. Once τ approaches 1.0, P, Ps/P and (Pt-P)/Pt mutate.
Analyzing the working principles and internal compression processes of an oil-gas multiphase pump, its theoretical calculation formulas is deduced, its input power P, its additional input power Ps and the input power Pt of external compression pump. With an actual example, the changes in P, Ps/P and (Pt -P)/Pt of pumps are summarized under the internal compression ratio λ (by changing the suction pressure p1 and the discharge pressure pd) and the gas-liquid ratio τ. When λ is constant, P decreases, Ps/P and (Pt-P)/Pt increase with τ increasing. If λ changes, the relationship between P and λ is more complicated; Ps/P always decreases with λ increasing and (Pt-P)/Pt behaves in an opposite way. P changes faster when p1 changes in relation to the changing pd; Ps/P behaves in an opposite way; (Pt-P)/Pt has little change. Once τ approaches 1.0, P, Ps/P and (Pt-P)/Pt mutate.
2015, 34(5): 699-705.
doi: 10.13433/j.cnki.1003-8728.2015.0509
Abstract:
The orthogonal experimental design method was used to optimize its technological parameters such as pulse-on time, pulse-off time, peak pulse current, wire cylinder speed and tracking coefficient of the medium-speed WEDM process. The relationship between process parameters and surface roughness (Ra) and the material removal rate (MRR) were modeled with the generalized regression method. Then the important factors that affect Ra and MRR are obtained with the signal to noise ratio (S/N Ratio) analysis. Finally, the non-dominated sorting genetic algorithm II (NSGA2) was used to optimize MRR and Ra. The effects of the corresponding parameters on optimal results were discussed. When the population size and the genetic number are larger enough, the adequate and uniform distribution Pareto front can be obtained.
The orthogonal experimental design method was used to optimize its technological parameters such as pulse-on time, pulse-off time, peak pulse current, wire cylinder speed and tracking coefficient of the medium-speed WEDM process. The relationship between process parameters and surface roughness (Ra) and the material removal rate (MRR) were modeled with the generalized regression method. Then the important factors that affect Ra and MRR are obtained with the signal to noise ratio (S/N Ratio) analysis. Finally, the non-dominated sorting genetic algorithm II (NSGA2) was used to optimize MRR and Ra. The effects of the corresponding parameters on optimal results were discussed. When the population size and the genetic number are larger enough, the adequate and uniform distribution Pareto front can be obtained.
2015, 34(5): 706-709.
doi: 10.13433/j.cnki.1003-8728.2015.0510
Abstract:
In this paper, the cutting speed, central offset, axial feed rate were considered as the three process parameters affecting the delamination. To get the cutting parameters database and the corresponding delamination, a large amount of experiments were planed using three levels three-factor full factorial design of experiments (FFD). Specific tool for helical milling with TiAlN coating was used in the experiments. Based on the experimental results, a multi-variant non-linear regression model was developed with the statistical software SPSS. With the mathematical model, three response surface figures can be drawn with MATLAB. Through the analysis of the figures, the two major factors influencing the delamination were pointed out.
In this paper, the cutting speed, central offset, axial feed rate were considered as the three process parameters affecting the delamination. To get the cutting parameters database and the corresponding delamination, a large amount of experiments were planed using three levels three-factor full factorial design of experiments (FFD). Specific tool for helical milling with TiAlN coating was used in the experiments. Based on the experimental results, a multi-variant non-linear regression model was developed with the statistical software SPSS. With the mathematical model, three response surface figures can be drawn with MATLAB. Through the analysis of the figures, the two major factors influencing the delamination were pointed out.
2015, 34(5): 710-714.
doi: 10.13433/j.cnki.1003-8728.2015.0511
Abstract:
To analyze the production capacity of precision casting line with mixed production, an approach of production capacity analysis based on the balance was proposed. This approach took the equipment capacity constraints of production line sections into account and established a multi-objective model, which minimized the statistical standard deviation of sections load ratio and maximized the production. A parallel NSGA-II algorithm was adopted to solve the present model. Finally, an example of a precision casting line was taken to prove the model effectiveness in production capacity check, bottleneck identification and balance adjustment of production line.
To analyze the production capacity of precision casting line with mixed production, an approach of production capacity analysis based on the balance was proposed. This approach took the equipment capacity constraints of production line sections into account and established a multi-objective model, which minimized the statistical standard deviation of sections load ratio and maximized the production. A parallel NSGA-II algorithm was adopted to solve the present model. Finally, an example of a precision casting line was taken to prove the model effectiveness in production capacity check, bottleneck identification and balance adjustment of production line.
2015, 34(5): 715-719.
doi: 10.13433/j.cnki.1003-8728.2015.0512
Abstract:
To optimize grinding parameters of ultra-high strength steel Aermet100, this paper applies the response surface method to investigating the model for predicting the force in grinding the surface of Aermet100, and establishes all coefficient regression models of the grinding force. The significance test method is used to determine whether or not each item in the model has significant effect on the grinding force, and a simplified model is obtained through removing the item which is not significant for the original model. In addition, the influence of process parameters on grinding force is analyzed based on the prediction model. The results show that the error of the simplified model of grinding force is small, and the grinding force can be effectively predicted; the interaction of grinding depth ap with workpiece speed vw and grinding wheel speed vs respectively is significant; grinding force increases with the increase of both workpiece speed vw and grinding depth ap, while decreasing with the increase of wheel speed vs.
To optimize grinding parameters of ultra-high strength steel Aermet100, this paper applies the response surface method to investigating the model for predicting the force in grinding the surface of Aermet100, and establishes all coefficient regression models of the grinding force. The significance test method is used to determine whether or not each item in the model has significant effect on the grinding force, and a simplified model is obtained through removing the item which is not significant for the original model. In addition, the influence of process parameters on grinding force is analyzed based on the prediction model. The results show that the error of the simplified model of grinding force is small, and the grinding force can be effectively predicted; the interaction of grinding depth ap with workpiece speed vw and grinding wheel speed vs respectively is significant; grinding force increases with the increase of both workpiece speed vw and grinding depth ap, while decreasing with the increase of wheel speed vs.
2015, 34(5): 720-723.
doi: 10.13433/j.cnki.1003-8728.2015.0513
Abstract:
In order to locate the workpiece, a positioning error model is established. First, based on the ideal pin-hole imaging model, the relationship between the horizontal and vertical coordinates of the points on a plane in space and the image coordinates can be acquired to position the points on the plane. The analysis concludes that the key factor which affects the positioning error is the radial distortion of the imaging system. The positioning error model is established based on the radial distortion model. Finally, through experiments and camera calibration, 144 corners of a planar checkerboard are located and undetermined coefficients of the positioning error model are fitted. The error analysis results indicate that the R-square of the fitting is up to over 0.9. After compensation by the positioning error model, the positioning errors of the 144 corners of the planar checkerboard are greatly reduced from 2.15 mm and 1.94 mm to 0.62 mm and 0.29 mm. The analysis proves that the positioning error model based on monocular vision raised in this paper is correct and that the radial distortion is the key factor which affects the positioning error.
In order to locate the workpiece, a positioning error model is established. First, based on the ideal pin-hole imaging model, the relationship between the horizontal and vertical coordinates of the points on a plane in space and the image coordinates can be acquired to position the points on the plane. The analysis concludes that the key factor which affects the positioning error is the radial distortion of the imaging system. The positioning error model is established based on the radial distortion model. Finally, through experiments and camera calibration, 144 corners of a planar checkerboard are located and undetermined coefficients of the positioning error model are fitted. The error analysis results indicate that the R-square of the fitting is up to over 0.9. After compensation by the positioning error model, the positioning errors of the 144 corners of the planar checkerboard are greatly reduced from 2.15 mm and 1.94 mm to 0.62 mm and 0.29 mm. The analysis proves that the positioning error model based on monocular vision raised in this paper is correct and that the radial distortion is the key factor which affects the positioning error.
2015, 34(5): 724-728.
doi: 10.13433/j.cnki.1003-8728.2015.0514
Abstract:
Virtual product model database of Linear Guide is established. The model database system is based on the secondary development of Pro/Engineer software. Firstly, the system conducts parametric modeling for the components of Rolling Linear Guides, the system can automatically generate the component models by inputing the components parameters, and automatically assemble components and implement the intelligent the assembly of components. The model database system is established with Visual Studio 2005 as development tool and database functions provided by Pro/TOOLKIT and combining with the Access database on the secondary development of Pro/Engineer software. Therefore, the Linear Guides of HTPM manufacture is used as an example to illustrate the application of present method.
Virtual product model database of Linear Guide is established. The model database system is based on the secondary development of Pro/Engineer software. Firstly, the system conducts parametric modeling for the components of Rolling Linear Guides, the system can automatically generate the component models by inputing the components parameters, and automatically assemble components and implement the intelligent the assembly of components. The model database system is established with Visual Studio 2005 as development tool and database functions provided by Pro/TOOLKIT and combining with the Access database on the secondary development of Pro/Engineer software. Therefore, the Linear Guides of HTPM manufacture is used as an example to illustrate the application of present method.
2015, 34(5): 729-732.
doi: 10.13433/j.cnki.1003-8728.2015.0515
Abstract:
A BP neural network prediction method of roughness with genetic algorithm (GA) is proposed to solve the problem of low prediction precision. In the present method, GA is firstly used to determine the initial weights and threshold by global optimization, and then the optimal BP neural network is used to train and predict the roughness. A simulation of the roughness prediction is executed with MATLAB. The simulation results show that the prediction accuracy of roughness with BP neural network is higher than that the un-optimal BP neural network.
A BP neural network prediction method of roughness with genetic algorithm (GA) is proposed to solve the problem of low prediction precision. In the present method, GA is firstly used to determine the initial weights and threshold by global optimization, and then the optimal BP neural network is used to train and predict the roughness. A simulation of the roughness prediction is executed with MATLAB. The simulation results show that the prediction accuracy of roughness with BP neural network is higher than that the un-optimal BP neural network.
2015, 34(5): 733-736.
doi: 10.13433/j.cnki.1003-8728.2015.0516
Abstract:
In curve machining, the curve trajectory was approached by the continuous small straight line segments. Then, the theoretic trajectory length was not exactly equal to the actual machining length. Therefore, a new algorithm was proposed to solve the problem, which realized the accurate acceleration-deceleration control for the curve machining by adjusting the actual machining length via dichotomy. The simulation result of a practical example demonstrates that the present algorithm can make the interpolation terminal point match up to the curve trajectory terminal point and do the theoretic acceleration/deceleration velocity profile consist with the actual acceleration/deceleration velocity profile. The present algorithm can improve the machining precision of curve trajectory and ameliorate the dynamic performance.
In curve machining, the curve trajectory was approached by the continuous small straight line segments. Then, the theoretic trajectory length was not exactly equal to the actual machining length. Therefore, a new algorithm was proposed to solve the problem, which realized the accurate acceleration-deceleration control for the curve machining by adjusting the actual machining length via dichotomy. The simulation result of a practical example demonstrates that the present algorithm can make the interpolation terminal point match up to the curve trajectory terminal point and do the theoretic acceleration/deceleration velocity profile consist with the actual acceleration/deceleration velocity profile. The present algorithm can improve the machining precision of curve trajectory and ameliorate the dynamic performance.
2015, 34(5): 737-741.
doi: 10.13433/j.cnki.1003-8728.2015.0517
Abstract:
Aim at the numerically fluctuated prediction of the ultrasonic vibration grinding assisted by EDM(electric discharge machining) in application of the models is built based on the machine learning theory, a processing prediction model based on the support vector machine(SVM). Taking the ultrasonic vibration grinding of SiCp/Al assisted by EDM as an example, learning samples with orthogonal tests and establish the prediction model is constructed based on SVM on the MATLAB platform. Then the model is used to predict two indicators such as surface roughness and processing velocity. The research results show that the prediction results of the processing prediction model are in accord with the test results. When the maximum relative error is less than 12% and the prediction value being highly accurate, the prediction model is reliable and effective.
Aim at the numerically fluctuated prediction of the ultrasonic vibration grinding assisted by EDM(electric discharge machining) in application of the models is built based on the machine learning theory, a processing prediction model based on the support vector machine(SVM). Taking the ultrasonic vibration grinding of SiCp/Al assisted by EDM as an example, learning samples with orthogonal tests and establish the prediction model is constructed based on SVM on the MATLAB platform. Then the model is used to predict two indicators such as surface roughness and processing velocity. The research results show that the prediction results of the processing prediction model are in accord with the test results. When the maximum relative error is less than 12% and the prediction value being highly accurate, the prediction model is reliable and effective.
2015, 34(5): 742-747.
doi: 10.13433/j.cnki.1003-8728.2015.0518
Abstract:
A new design method for longitudinal-torsional composite of the ultrasonic vibration system was put forward and the finite element software ANSYS was used to validate this method. Firstly, based on the transfer matrix theory, the resonance frequency equations and the vibration velocity amplification coefficient for the longitudinal-torsional composite vibration of the horn were derived. Meanwhile, the resonance frequency equations were solved by using the software of MATLAB. Then, stress states of the rod when the longitudinal and torsional vibration travels in the rod were studied, and a new incentive mechanism for longitudinal and torsional vibration mode was put forward. Finally, a new type of longitudinal-torsional composite of the ultrasonic vibration system was designed and its dynamic characteristics were calculated using ANSYS. Results show that the calculated resonant frequencies agree well with the designed frequencies, and the longitudinal vibration frequency and torsional vibration frequency are almost equal to each other.
A new design method for longitudinal-torsional composite of the ultrasonic vibration system was put forward and the finite element software ANSYS was used to validate this method. Firstly, based on the transfer matrix theory, the resonance frequency equations and the vibration velocity amplification coefficient for the longitudinal-torsional composite vibration of the horn were derived. Meanwhile, the resonance frequency equations were solved by using the software of MATLAB. Then, stress states of the rod when the longitudinal and torsional vibration travels in the rod were studied, and a new incentive mechanism for longitudinal and torsional vibration mode was put forward. Finally, a new type of longitudinal-torsional composite of the ultrasonic vibration system was designed and its dynamic characteristics were calculated using ANSYS. Results show that the calculated resonant frequencies agree well with the designed frequencies, and the longitudinal vibration frequency and torsional vibration frequency are almost equal to each other.
2015, 34(5): 748-751.
doi: 10.13433/j.cnki.1003-8728.2015.0519
Abstract:
In order to solve the complexities of fault diagnosis and maintenance for fast forging hydraulic press, a web-based remote monitoring and fault diagnosis system to maintain fast forging hydraulic press is established. On the basis of the overall structure analysis of the system, the concrete realization of system features is elaborated. In the next section, 20 MN fast forging hydraulic press is taken as the example to illustrate the workflow of remote monitoring and fault diagnosis system and the related technologies of fast forging hydraulic press. The system realizes real-time monitoring, remote diagnosis, method feedback and many other functions which including the Browser/Server three-tier structure and the network superiority in collecting and sharing information. The implementation of this system can well solve the problems about rapid diagnosis of fast forging hydraulic equipment faults, and also facilitate equipment use, maintenance and management.
In order to solve the complexities of fault diagnosis and maintenance for fast forging hydraulic press, a web-based remote monitoring and fault diagnosis system to maintain fast forging hydraulic press is established. On the basis of the overall structure analysis of the system, the concrete realization of system features is elaborated. In the next section, 20 MN fast forging hydraulic press is taken as the example to illustrate the workflow of remote monitoring and fault diagnosis system and the related technologies of fast forging hydraulic press. The system realizes real-time monitoring, remote diagnosis, method feedback and many other functions which including the Browser/Server three-tier structure and the network superiority in collecting and sharing information. The implementation of this system can well solve the problems about rapid diagnosis of fast forging hydraulic equipment faults, and also facilitate equipment use, maintenance and management.
2015, 34(5): 752-757.
doi: 10.13433/j.cnki.1003-8728.2015.0520
Abstract:
Based on operating principles of the vertical microstructure profiler (VMP), requirements for its sinking velocity were discussed and the range of its sinking velocity was determined. After analyzing the factors that affect the sinking velocity, the method for controlling it was presented namely adjusting the hydraulic drag during the profiler's free-falling. Based on dynamic mesh, the fluid-structure coupling was calculated with the ANSYS-CFX codes to solve the hydraulic drag of the VMP with elastic drag whiskers. The calculation accuracy was verified by sea tests.
Based on operating principles of the vertical microstructure profiler (VMP), requirements for its sinking velocity were discussed and the range of its sinking velocity was determined. After analyzing the factors that affect the sinking velocity, the method for controlling it was presented namely adjusting the hydraulic drag during the profiler's free-falling. Based on dynamic mesh, the fluid-structure coupling was calculated with the ANSYS-CFX codes to solve the hydraulic drag of the VMP with elastic drag whiskers. The calculation accuracy was verified by sea tests.
2015, 34(5): 758-762.
doi: 10.13433/j.cnki.1003-8728.2015.0521
Abstract:
A large thrust double U-typed permanent-magnet linear motor used in Bridge Type Gantry Five-axis Machining Center is studied and designed, and its performance was tested. Firstly, the linear motor's basic dimensions, form of windings and magnet arrangement based on the application environment and the requirement of motor performance parameters are analyzed and calculated. Secondly, the finite element model for motor is established on the basis of the analysis results, and the static and dynamic characteristics of the motor is studied and analyzed through the finite element method. The final design scheme for motor is determined and manufactured. Finally, the performance of motor is fully tested applying the evaluation platform for direct-drive motor component. Experimental results meet the design requirements and show the effectiveness of design method and process.
A large thrust double U-typed permanent-magnet linear motor used in Bridge Type Gantry Five-axis Machining Center is studied and designed, and its performance was tested. Firstly, the linear motor's basic dimensions, form of windings and magnet arrangement based on the application environment and the requirement of motor performance parameters are analyzed and calculated. Secondly, the finite element model for motor is established on the basis of the analysis results, and the static and dynamic characteristics of the motor is studied and analyzed through the finite element method. The final design scheme for motor is determined and manufactured. Finally, the performance of motor is fully tested applying the evaluation platform for direct-drive motor component. Experimental results meet the design requirements and show the effectiveness of design method and process.
2015, 34(5): 763-769.
doi: 10.13433/j.cnki.1003-8728.2015.0522
Abstract:
In order to realize the flexible processing control of a servo press, the paper analyzes the drive system of a crank toggle servo press, proposes the servo press control strategy with the Bezier mathematical model, and gives the specific control scheme. Then it further proposes the transverse flux machine control strategy with the armature current RMS control and phase control and establishes the servo motor control system to precisely control the crank operation. Eventually the slider can be controlled with the flexible processing curves calculated by the Bezier mathematical model. The results on the simulation of punching process control show that the control system can achieve the precision slide operation curve, which is in agreement with processing requirements.
In order to realize the flexible processing control of a servo press, the paper analyzes the drive system of a crank toggle servo press, proposes the servo press control strategy with the Bezier mathematical model, and gives the specific control scheme. Then it further proposes the transverse flux machine control strategy with the armature current RMS control and phase control and establishes the servo motor control system to precisely control the crank operation. Eventually the slider can be controlled with the flexible processing curves calculated by the Bezier mathematical model. The results on the simulation of punching process control show that the control system can achieve the precision slide operation curve, which is in agreement with processing requirements.
2015, 34(5): 770-774.
doi: 10.13433/j.cnki.1003-8728.2015.0523
Abstract:
In order to build more accurate model for an inerter and improve design theories and methods of inerter, the influence of the nonlinear factors on the inerter was investigated. A screw-rotation ballscrew inerter was designed, and its test bench was established. With the system identification, the test data of the time domain response were turned into the frequency domain, and then the frequency response characteristics curves of inerter were obtained. The Malcolm linear model for inerter was taken as a comparing object of the test to analyze influence of the friction force on the frequency response characteristics of ballscrew inerter in the condition of no backlash. The results show that at low frequencies, the friction force dominates in the inerter so as to decrease it's the phase and increase the amplitude as well. With the increasing of frequency and inertance, the influence of the friction force on the inerter relatively reduces, and its actual performance gradually approaches the theoretical.
In order to build more accurate model for an inerter and improve design theories and methods of inerter, the influence of the nonlinear factors on the inerter was investigated. A screw-rotation ballscrew inerter was designed, and its test bench was established. With the system identification, the test data of the time domain response were turned into the frequency domain, and then the frequency response characteristics curves of inerter were obtained. The Malcolm linear model for inerter was taken as a comparing object of the test to analyze influence of the friction force on the frequency response characteristics of ballscrew inerter in the condition of no backlash. The results show that at low frequencies, the friction force dominates in the inerter so as to decrease it's the phase and increase the amplitude as well. With the increasing of frequency and inertance, the influence of the friction force on the inerter relatively reduces, and its actual performance gradually approaches the theoretical.
2015, 34(5): 775-779.
doi: 10.13433/j.cnki.1003-8728.2015.0524
Abstract:
The flexible car body vibration disturbed by the track irregularity influenced vehicle stability. A vertical dynamics model for railway passenger carriages is established based on the principle of rigid-flexible coupled dynamics. The modal frequencies and power spectrum density (PSD) of the system response are calculated based on the resonance and modal superposition theory. The influence of the vehicle suspension parameters and running parameters on the vibration are analyzed. The numerical simulation results show that the elastic car body model vibration is larger than the rigid one. The first-order bending vibration has the most important role for the elastic vibration. The adequate vertical suspension damping and primary suspension stiffness can be adopted to reduce the car body elastic vibration in the structure design. The system components vibration frequency control and the car body suspension damping control can achieve the global car modal and local harmful modal control.
The flexible car body vibration disturbed by the track irregularity influenced vehicle stability. A vertical dynamics model for railway passenger carriages is established based on the principle of rigid-flexible coupled dynamics. The modal frequencies and power spectrum density (PSD) of the system response are calculated based on the resonance and modal superposition theory. The influence of the vehicle suspension parameters and running parameters on the vibration are analyzed. The numerical simulation results show that the elastic car body model vibration is larger than the rigid one. The first-order bending vibration has the most important role for the elastic vibration. The adequate vertical suspension damping and primary suspension stiffness can be adopted to reduce the car body elastic vibration in the structure design. The system components vibration frequency control and the car body suspension damping control can achieve the global car modal and local harmful modal control.
2015, 34(5): 780-784.
doi: 10.13433/j.cnki.1003-8728.2015.0525
Abstract:
Taking a car for example, we presented the simulation principle and calculation steps of its external flow field. With both the RNG k-epsilon and the large eddy simulation (LES) method,the numerical simulation of the external flow field of the car body under three different speeds was conducted with the FLUENT, a CFD software. The calculation results indeed reflect the aerodynamic characteristics of the external flow field of the car, and the separated flow movement on the car body surface is better simulated. In addition, the positions where the vortex motion is relatively severe are also found.
Taking a car for example, we presented the simulation principle and calculation steps of its external flow field. With both the RNG k-epsilon and the large eddy simulation (LES) method,the numerical simulation of the external flow field of the car body under three different speeds was conducted with the FLUENT, a CFD software. The calculation results indeed reflect the aerodynamic characteristics of the external flow field of the car, and the separated flow movement on the car body surface is better simulated. In addition, the positions where the vortex motion is relatively severe are also found.
2015, 34(5): 785-789.
doi: 10.13433/j.cnki.1003-8728.2015.0526
Abstract:
Based on the progressive damage analysis, a three dimensional (3D) finite element model for composite laminate is built. The model is consisted of the stress analysis, judgement of element failure and property degradation of damaged element. The modified non-linear 3D Hashin criterion is used to judge the element damage, and Camanho property degradation model is to degrades damaged elements. By coding the user material subroutine (UMAT), the application of failure criterion and property degradation model is written in Abaqus. The finite element model is validated by comparing with the experimental results. The diffrence between the calculated and experimental value is 8.7%. The failure position and failure mode ia in a better agreement with the experimental results, which shows that the model can be used to predict the strength and analyze the damage of laminate composite.
Based on the progressive damage analysis, a three dimensional (3D) finite element model for composite laminate is built. The model is consisted of the stress analysis, judgement of element failure and property degradation of damaged element. The modified non-linear 3D Hashin criterion is used to judge the element damage, and Camanho property degradation model is to degrades damaged elements. By coding the user material subroutine (UMAT), the application of failure criterion and property degradation model is written in Abaqus. The finite element model is validated by comparing with the experimental results. The diffrence between the calculated and experimental value is 8.7%. The failure position and failure mode ia in a better agreement with the experimental results, which shows that the model can be used to predict the strength and analyze the damage of laminate composite.
2015, 34(5): 790-794.
doi: 10.13433/j.cnki.1003-8728.2015.0527
Abstract:
Usually, it costs a lot of time to establish the model of the hydro-mechanical units of an aero-engine. However, the reusability of the models often fails to achieve the anticipation. An object oriented classified method is put forward, which classifies different functional models into a category and orders them regularly into the component library. All these works are based on the AMESim programming environment. The component library has the characteristics of expansibility, practical applicability and reusability. It's convenient to model and analyze hydro-mechanical units for a new type of aero-engine. It's easy to reuse the existing components and statistics, and the library is conducive to the development of hydro-mechanical units with serialization, standardization and universalization.
Usually, it costs a lot of time to establish the model of the hydro-mechanical units of an aero-engine. However, the reusability of the models often fails to achieve the anticipation. An object oriented classified method is put forward, which classifies different functional models into a category and orders them regularly into the component library. All these works are based on the AMESim programming environment. The component library has the characteristics of expansibility, practical applicability and reusability. It's convenient to model and analyze hydro-mechanical units for a new type of aero-engine. It's easy to reuse the existing components and statistics, and the library is conducive to the development of hydro-mechanical units with serialization, standardization and universalization.
2015, 34(5): 795-798.
doi: 10.13433/j.cnki.1003-8728.2015.0528
Abstract:
To predict the load-carrying capacity is crucial in the aircraft design procedure, various methods of modeling in the post-buckling analysis are respectively investigated on the integral stiffened structures and riveted stiffened structures. Comparing the analytic with experimental data, we indicatec suitable discreting method could exactly predict the failure load for two kinds of the stiffened structural shape. Correlation between finite element (FE) predictions and the test data is very good for analyzing & validating the wing box including integral stiffened panels and rivet connectors.
To predict the load-carrying capacity is crucial in the aircraft design procedure, various methods of modeling in the post-buckling analysis are respectively investigated on the integral stiffened structures and riveted stiffened structures. Comparing the analytic with experimental data, we indicatec suitable discreting method could exactly predict the failure load for two kinds of the stiffened structural shape. Correlation between finite element (FE) predictions and the test data is very good for analyzing & validating the wing box including integral stiffened panels and rivet connectors.
2015, 34(5): 799-802.
doi: 10.13433/j.cnki.1003-8728.2015.0529
Abstract:
The aim of the present study is to solve the control effectiveness problem in aft swept wing design by aeroelastic tailoring of the composite skin. Parametric analysis was carried out for the ply stacking ratio and thickness of the composite skin to study the influence on the static strength and control effectiveness. Based on the parametric trends obtained, a novel engineering strategy was proposed to reduce the weight of composite skin while keeping the control effectiveness. With such strategy, ply stacking ratio and the composite skin thickness were selected as design variables, and the objective function was the lowest skin weight considering the static strength constraint under critical load case and the control effectiveness constraint under typical flight condition. The optimization problem was solved successfully by MSC.Nastran SOL 200 solver for aeroelastic tailoring of an aft swept wing with composite skin.
The aim of the present study is to solve the control effectiveness problem in aft swept wing design by aeroelastic tailoring of the composite skin. Parametric analysis was carried out for the ply stacking ratio and thickness of the composite skin to study the influence on the static strength and control effectiveness. Based on the parametric trends obtained, a novel engineering strategy was proposed to reduce the weight of composite skin while keeping the control effectiveness. With such strategy, ply stacking ratio and the composite skin thickness were selected as design variables, and the objective function was the lowest skin weight considering the static strength constraint under critical load case and the control effectiveness constraint under typical flight condition. The optimization problem was solved successfully by MSC.Nastran SOL 200 solver for aeroelastic tailoring of an aft swept wing with composite skin.
2015, 34(5): 803-807.
doi: 10.13433/j.cnki.1003-8728.2015.0530
Abstract:
The paper obtains the stress intensity factors (SIF) of a plate with multiple mixed-mode cracks with the displacement extrapolation method and the finite element method, and studies in detail the effects of some parameters on the SIF, which include the length of rectangular plate, crack length, crack separation ratio. Comparing the simulation results with the analytical solutions, we demonstrate the feasibility of the displacement extrapolation method. The side crack of small size and the large crack separation ratio have little effect on the SIF of a central crack. It can be seen as an infinite plate when the length of rectangular plate is eight times larger than the crack length. The three cracks can be seen as a single crack separately when the horizontal distance L or vertical distance h is six times or nine times larger than the crack length b. The reason is that the interaction among multiple mixed-mode cracks can be ignored when L/b>9 or h/b>6.
The paper obtains the stress intensity factors (SIF) of a plate with multiple mixed-mode cracks with the displacement extrapolation method and the finite element method, and studies in detail the effects of some parameters on the SIF, which include the length of rectangular plate, crack length, crack separation ratio. Comparing the simulation results with the analytical solutions, we demonstrate the feasibility of the displacement extrapolation method. The side crack of small size and the large crack separation ratio have little effect on the SIF of a central crack. It can be seen as an infinite plate when the length of rectangular plate is eight times larger than the crack length. The three cracks can be seen as a single crack separately when the horizontal distance L or vertical distance h is six times or nine times larger than the crack length b. The reason is that the interaction among multiple mixed-mode cracks can be ignored when L/b>9 or h/b>6.
2015, 34(5): 808-811.
doi: 10.13433/j.cnki.1003-8728.2015.0531
Abstract:
Fatigue tests were carried out for 7050-T7451 double-shear joints with different interferences and the fatigue life of joints was analyzed. Fatigue fracture behavior morphology characteristics of interference-fit bolted joints were studied with scanning electron microscope. The results show that 7050-T7451 double-shear bolted joints will obtain long fatigue life with interference of 0.08~0.14 mm, and the fatigue life of the joint with 0.11 mm interference is the longest. The fatigue crack fractography presents hybrid transgranular fracture characteristics and the material of 7050-T7451 has good toughness. Interference-fit bolted jointing can strengthen the wall of hole and make fatigue crack source from the surface of structure, not the wall of hole. The improvement of structure surface can benefit for increasing the fatigue life of joints.
Fatigue tests were carried out for 7050-T7451 double-shear joints with different interferences and the fatigue life of joints was analyzed. Fatigue fracture behavior morphology characteristics of interference-fit bolted joints were studied with scanning electron microscope. The results show that 7050-T7451 double-shear bolted joints will obtain long fatigue life with interference of 0.08~0.14 mm, and the fatigue life of the joint with 0.11 mm interference is the longest. The fatigue crack fractography presents hybrid transgranular fracture characteristics and the material of 7050-T7451 has good toughness. Interference-fit bolted jointing can strengthen the wall of hole and make fatigue crack source from the surface of structure, not the wall of hole. The improvement of structure surface can benefit for increasing the fatigue life of joints.
2015, 34(5): 812-816.
doi: 10.13433/j.cnki.1003-8728.2015.0532
Abstract:
According to the sun radiation at Nan-Shan, we obtain Xinjiang Astronomical Observatory, via finite element analysis software, the temperature distribution and thermal deformation. Simplify the details and the model was established in ANSYS, and the boundary conditions of solar radiation, periodic air temperature and long-wave radiation are computed each hour in a cloudless day (June 21th) in summer. Then the transient temperature analysis was conducted and the temperature distribution and the deformation of structure were obtained. The result indicated that: the temperature of the antenna mounts changes large in one day, the highest temperature difference reaches 9 ℃; the most serious deformation under sun radiation, which RMS(root mean square) up to 1.8 mm, this significantly influence the pointing accuracy of the antenna.
According to the sun radiation at Nan-Shan, we obtain Xinjiang Astronomical Observatory, via finite element analysis software, the temperature distribution and thermal deformation. Simplify the details and the model was established in ANSYS, and the boundary conditions of solar radiation, periodic air temperature and long-wave radiation are computed each hour in a cloudless day (June 21th) in summer. Then the transient temperature analysis was conducted and the temperature distribution and the deformation of structure were obtained. The result indicated that: the temperature of the antenna mounts changes large in one day, the highest temperature difference reaches 9 ℃; the most serious deformation under sun radiation, which RMS(root mean square) up to 1.8 mm, this significantly influence the pointing accuracy of the antenna.
2015, 34(5): 817-820.
doi: 10.13433/j.cnki.1003-8728.2015.0533
Abstract:
Flight load-model is important for flight load measurement, which is necessary for new type aircraft development. A concept of strain distribution proportion was proposed in this paper, and an adaptive measurement model of flight loads is built based on the above idea. Compared with traditional methods, the model can embody real strain response variation in flight tests, therefore the measurement results could agree better to the actual flight condition. Moreover, this method is applied to flight load measurement for certain aircraft, which results show this method is right.
Flight load-model is important for flight load measurement, which is necessary for new type aircraft development. A concept of strain distribution proportion was proposed in this paper, and an adaptive measurement model of flight loads is built based on the above idea. Compared with traditional methods, the model can embody real strain response variation in flight tests, therefore the measurement results could agree better to the actual flight condition. Moreover, this method is applied to flight load measurement for certain aircraft, which results show this method is right.
