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RSS2015 Vol. 34, No. 10
Display Method:
Structural Optimization and Dynamic Simulation of Aluminum Foil Rewinder Based on Kinematic Analysis
2015, 34(10): 1477-1481.
doi: 10.13433/j.cnki.1003-8728.2015.1001
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Abstract:
Aiming at the failure of the key component at the high-speed state and the insufficient stability of the equipment, we apply the master model technology to complete three-dimensional modeling of the rewinder. Then the comprehensive analysis of kinematics can be conducted after the rigid is defined and the constraints are imposed. The structural optimization and dynamic simulation of the core components are conducted to improve the performance parameters of the rewinder. The dynamic simulation analysis of the rewinder's ejector shaft which is the core component is made. The curve of position, velocity and the acceleration of the ejector shaft are optimized with the design of the cam mechanism. Finally, the optimization of structure of the ejector shaft is completed by analyzing the force curve. The optimized core components are applied to rewinding machine and achieve high-speed performance and stability requirements. The optimized rewinder is ultimately put into practice and achieve the desired results.
Aiming at the failure of the key component at the high-speed state and the insufficient stability of the equipment, we apply the master model technology to complete three-dimensional modeling of the rewinder. Then the comprehensive analysis of kinematics can be conducted after the rigid is defined and the constraints are imposed. The structural optimization and dynamic simulation of the core components are conducted to improve the performance parameters of the rewinder. The dynamic simulation analysis of the rewinder's ejector shaft which is the core component is made. The curve of position, velocity and the acceleration of the ejector shaft are optimized with the design of the cam mechanism. Finally, the optimization of structure of the ejector shaft is completed by analyzing the force curve. The optimized core components are applied to rewinding machine and achieve high-speed performance and stability requirements. The optimized rewinder is ultimately put into practice and achieve the desired results.
2015, 34(10): 1482-1487.
doi: 10.13433/j.cnki.1003-8728.2015.1002
Abstract:
The virtual prototype model of a large type excavator SH700-5 was built with the three-dimensional modeling software Pro/e and the dynamic simulation software ADAMS. In order to obtain the maximum digging force for the bucket and arm, the simulation and test for the digging force of working device were accomplished according to the GB measuring method and compared with the theoretically calculated value. The results show that under two different digging modes, the weight of working device will increase the digging force by about 4%and 8%, respectively. To study the changes of force acted on each hinged joints during the digging process, the action of the piston rods on working device was driven by bucket and arm respectively, and the loading resistance was exerted on the bucket to simulate the process of digging. the curves of the continuously changing force acted on the key hinged joints were obtained. The results indicate that the force value acted on hinged joint connecting the boom and stick is the biggest, the ratio of the maximum force and maximum digging resistance under two different digging modes are 4.69 and 7.13.
The virtual prototype model of a large type excavator SH700-5 was built with the three-dimensional modeling software Pro/e and the dynamic simulation software ADAMS. In order to obtain the maximum digging force for the bucket and arm, the simulation and test for the digging force of working device were accomplished according to the GB measuring method and compared with the theoretically calculated value. The results show that under two different digging modes, the weight of working device will increase the digging force by about 4%and 8%, respectively. To study the changes of force acted on each hinged joints during the digging process, the action of the piston rods on working device was driven by bucket and arm respectively, and the loading resistance was exerted on the bucket to simulate the process of digging. the curves of the continuously changing force acted on the key hinged joints were obtained. The results indicate that the force value acted on hinged joint connecting the boom and stick is the biggest, the ratio of the maximum force and maximum digging resistance under two different digging modes are 4.69 and 7.13.
2015, 34(10): 1488-1492.
doi: 10.13433/j.cnki.1003-8728.2015.1003
Abstract:
The crawler frame is working as a significant component for crawler travel unit. To obtain the optimal structure type satisfying the requirement of several loading conditions, three dimensional topological optimizations are introduced into the conceptual design of crawler frame. Both the mathematical model and the multi-stiffness topological optimization model of crawler frame are established by analyzing the typical loading conditions. To convert the multi-stiffness optimization problem into a single objective optimization, the weight compromise programming method is adopted, the calculation method of dynamic weight coefficient is proposed based on multi-objective satisfaction theory. Each weight coefficient is a nonlinear function of the corresponding single object, which can avoid the deviations of weight coefficient set by designers subjectively. Geometry model is reconstructed, followed by static analysis of the new structure. Compared with the analyzing results of the original structure, the results of optimized structure prove the validity of topological optimization of the crawler frame.
The crawler frame is working as a significant component for crawler travel unit. To obtain the optimal structure type satisfying the requirement of several loading conditions, three dimensional topological optimizations are introduced into the conceptual design of crawler frame. Both the mathematical model and the multi-stiffness topological optimization model of crawler frame are established by analyzing the typical loading conditions. To convert the multi-stiffness optimization problem into a single objective optimization, the weight compromise programming method is adopted, the calculation method of dynamic weight coefficient is proposed based on multi-objective satisfaction theory. Each weight coefficient is a nonlinear function of the corresponding single object, which can avoid the deviations of weight coefficient set by designers subjectively. Geometry model is reconstructed, followed by static analysis of the new structure. Compared with the analyzing results of the original structure, the results of optimized structure prove the validity of topological optimization of the crawler frame.
2015, 34(10): 1493-1498.
doi: 10.13433/j.cnki.1003-8728.2015.1004
Abstract:
Since the joint clearance and linkage elasticity has a comparatively large effect on the reliable operation of a transmission mechanism, considering rotation clearance and the linkage elasticity we established a mechanism analytical model based on the ideal state of the mechanism. The three transmission mechanisms:the ideal mechanism, mechanism with clearance and mechanism with both linkage elasticity and clearance were simulated with ADAMS software. The displacement, velocity, acceleration and the changing rule of the joints contact force for the transmission mechanism were finally obtained. The results show that the in-collisions has led to large fluctuations of the acceleration and contact force, which were produced in the shaft pins and bushings of clearance joints; the acceleration and vice force generated in the clearance were reduced and the contact time was increased while considering the linkage elasticity. This means that the linkage elasticity has a buffering effect on the collision of the shaft pins and bushings in the clearance joints,therefore.
Since the joint clearance and linkage elasticity has a comparatively large effect on the reliable operation of a transmission mechanism, considering rotation clearance and the linkage elasticity we established a mechanism analytical model based on the ideal state of the mechanism. The three transmission mechanisms:the ideal mechanism, mechanism with clearance and mechanism with both linkage elasticity and clearance were simulated with ADAMS software. The displacement, velocity, acceleration and the changing rule of the joints contact force for the transmission mechanism were finally obtained. The results show that the in-collisions has led to large fluctuations of the acceleration and contact force, which were produced in the shaft pins and bushings of clearance joints; the acceleration and vice force generated in the clearance were reduced and the contact time was increased while considering the linkage elasticity. This means that the linkage elasticity has a buffering effect on the collision of the shaft pins and bushings in the clearance joints,therefore.
2015, 34(10): 1499-1503.
doi: 10.13433/j.cnki.1003-8728.2015.1005
Abstract:
According to the overall design idea of 6 500 m3/min displacement giant water ring vacuum-pump, we carried on the specific design of the impeller. Theoretical and experiential methods were used to design the total size of the impeller in order to satisfy the requirement of displacement. The model was built with ANSYS software and the strength, stiffness and modal analyses were conducted so as to confirm whether the strength and stiffness is enough. Then size optimization was performed for the impeller to reduce the weight and production cost while the work conditions were satisfied. The proposed design and analysis can relieve the dependence of experience on impeller design.
According to the overall design idea of 6 500 m3/min displacement giant water ring vacuum-pump, we carried on the specific design of the impeller. Theoretical and experiential methods were used to design the total size of the impeller in order to satisfy the requirement of displacement. The model was built with ANSYS software and the strength, stiffness and modal analyses were conducted so as to confirm whether the strength and stiffness is enough. Then size optimization was performed for the impeller to reduce the weight and production cost while the work conditions were satisfied. The proposed design and analysis can relieve the dependence of experience on impeller design.
2015, 34(10): 1504-1510.
doi: 10.13433/j.cnki.1003-8728.2015.1006
Abstract:
The calibration method for the inverse kinematics based on the structure parameters and genetic algorithm is put forward, the error calibration model for Parallel machine tool(PMT) is derived. The method does not need to calculate the forward solution for the parallel spindle platform, the complex forward motion analysis for PMT is avoided. The calculated results show:the inverse kinematics error of the nominal structure parameters is significantly higher than that of the calibration structure parameters; three calibrated positions of cylindrical joint and ball joint are closer to the nominal position, that is, the error calibration can correct the structure of machine tools.
The calibration method for the inverse kinematics based on the structure parameters and genetic algorithm is put forward, the error calibration model for Parallel machine tool(PMT) is derived. The method does not need to calculate the forward solution for the parallel spindle platform, the complex forward motion analysis for PMT is avoided. The calculated results show:the inverse kinematics error of the nominal structure parameters is significantly higher than that of the calibration structure parameters; three calibrated positions of cylindrical joint and ball joint are closer to the nominal position, that is, the error calibration can correct the structure of machine tools.
2015, 34(10): 1511-1516.
doi: 10.13433/j.cnki.1003-8728.2015.1007
Abstract:
Aiming at the problem of traditional local obstacle avoidance algorithm based on gradient projection method that only adjusts joint space, we present an improved obstacle avoidance algorithm. The obstacle avoidance path of the robot end is real-time planned out with the artificial potential field algorithm. The shortest distance index is used to adjust the robot in joint space to avoid collision. The improved obstacle avoidance algorithm is realized with the combination of robot end obstacle avoidance and joint space adjustment. The shortest distance is calculated with analytical method to avoid the shortest distance falling on the member bar production. The simulation of obstacle avoidance is carried out with MATLAB software. The planning takes 1.73s and it verifies the effectiveness and efficiency of the improved obstacle avoidance algorithm, and the algorithm is also applicable to target pursuit and obstacle avoidance in dynamic environment.
Aiming at the problem of traditional local obstacle avoidance algorithm based on gradient projection method that only adjusts joint space, we present an improved obstacle avoidance algorithm. The obstacle avoidance path of the robot end is real-time planned out with the artificial potential field algorithm. The shortest distance index is used to adjust the robot in joint space to avoid collision. The improved obstacle avoidance algorithm is realized with the combination of robot end obstacle avoidance and joint space adjustment. The shortest distance is calculated with analytical method to avoid the shortest distance falling on the member bar production. The simulation of obstacle avoidance is carried out with MATLAB software. The planning takes 1.73s and it verifies the effectiveness and efficiency of the improved obstacle avoidance algorithm, and the algorithm is also applicable to target pursuit and obstacle avoidance in dynamic environment.
2015, 34(10): 1517-1520.
doi: 10.13433/j.cnki.1003-8728.2015.1008
Abstract:
Aiming at the limitations of the rational alignment method under loading of bearing which does not include the propulsion force or does not make the ratio of the load of the afterward stern-tube bearing to the load of the forward stern-tube bearing less than 1/3 when included the propulsion force, we propose a new rational alignment method of the propulsion shaft, which can ensure the load ratio to be the optimum when the propulsion force is taken into consideration and the propulsion moment is not included in. The shaft-line of a running propulsion shaft was optimized and the shaft alignment calculation was carried out for the model of a simplified propulsion shaft. If the propulsion force is not taken into consideration, the load ratio is less than 1/3, but when the propulsion force, which is 50% of the maximum propulsion force, is taken into consideration, the load ratio is in the scope of[1/2,1/3]. The result illustrated that if the load ratio is in the scope of[1/2,1/3], the shaft-line is curvilinear and all bearings of propulsion shaft are not in a straight-line.
Aiming at the limitations of the rational alignment method under loading of bearing which does not include the propulsion force or does not make the ratio of the load of the afterward stern-tube bearing to the load of the forward stern-tube bearing less than 1/3 when included the propulsion force, we propose a new rational alignment method of the propulsion shaft, which can ensure the load ratio to be the optimum when the propulsion force is taken into consideration and the propulsion moment is not included in. The shaft-line of a running propulsion shaft was optimized and the shaft alignment calculation was carried out for the model of a simplified propulsion shaft. If the propulsion force is not taken into consideration, the load ratio is less than 1/3, but when the propulsion force, which is 50% of the maximum propulsion force, is taken into consideration, the load ratio is in the scope of[1/2,1/3]. The result illustrated that if the load ratio is in the scope of[1/2,1/3], the shaft-line is curvilinear and all bearings of propulsion shaft are not in a straight-line.
2015, 34(10): 1521-1525.
doi: 10.13433/j.cnki.1003-8728.2015.1009
Abstract:
The influence of the processing parameters, including spindle rotational speed, tangential federate per tooth, and pitch on the surface integrity of hole in the helical milling process was studied. A series of orthogonal experiments in the helical milling process of TC4 titanium alloy were conducted, and the effect of the processing parameters on the surface roughness, micro-hardness distribution, residual stress distribution and microstructure evolution were studied with surface roughness tester, micro-hardness tester, X ray diffractometer, and metallographical microscope. The results revealed that the surface roughness of hole in the helical milled process can meet the requirement in aerospace industry with the maximum value of Ra 0.431μm; the proper work-hardening with hardening capability of 129%~141% can improve the abrasive resistance; the compressive residual stress can improve the fatigue performance; no "white layer" is found in the surface/subsurface of hole due to the favorable heat dissipation and the small mechanical load. Therefore, the helical milling technology can substantially improve the surface integrity of making-hole for TC4 titanium alloy.
The influence of the processing parameters, including spindle rotational speed, tangential federate per tooth, and pitch on the surface integrity of hole in the helical milling process was studied. A series of orthogonal experiments in the helical milling process of TC4 titanium alloy were conducted, and the effect of the processing parameters on the surface roughness, micro-hardness distribution, residual stress distribution and microstructure evolution were studied with surface roughness tester, micro-hardness tester, X ray diffractometer, and metallographical microscope. The results revealed that the surface roughness of hole in the helical milled process can meet the requirement in aerospace industry with the maximum value of Ra 0.431μm; the proper work-hardening with hardening capability of 129%~141% can improve the abrasive resistance; the compressive residual stress can improve the fatigue performance; no "white layer" is found in the surface/subsurface of hole due to the favorable heat dissipation and the small mechanical load. Therefore, the helical milling technology can substantially improve the surface integrity of making-hole for TC4 titanium alloy.
2015, 34(10): 1526-1529.
doi: 10.13433/j.cnki.1003-8728.2015.1010
Abstract:
This paper designs an air turbine-driven spindle which is supported by air bearings for ultra-precision machining of a microstructure. An air turbine is used as the micro-structure powered with high-pressure air, and three air bearings are used as the supporting device. The design model of air turbine is established, and the structural parameters of air bearings are analyzed. The effects of various design parameters on the capacity of air bearing were simulated, and the optimal dimensions and working parameters were obtained. Moreover, the natural frequency of the turbine and its rotor including the shaft is studied, thus obtaining the critical rotational speed. Finally the paper studies the machining process of the air turbine-driven spindle and conducts experiments on the spindle. The experimental results show that our design method is reasonable and meets the design requirements.
This paper designs an air turbine-driven spindle which is supported by air bearings for ultra-precision machining of a microstructure. An air turbine is used as the micro-structure powered with high-pressure air, and three air bearings are used as the supporting device. The design model of air turbine is established, and the structural parameters of air bearings are analyzed. The effects of various design parameters on the capacity of air bearing were simulated, and the optimal dimensions and working parameters were obtained. Moreover, the natural frequency of the turbine and its rotor including the shaft is studied, thus obtaining the critical rotational speed. Finally the paper studies the machining process of the air turbine-driven spindle and conducts experiments on the spindle. The experimental results show that our design method is reasonable and meets the design requirements.
2015, 34(10): 1530-1535.
doi: 10.13433/j.cnki.1003-8728.2015.1011
Abstract:
Based on the nonlinear finite element method, a horizontal stiffness calculation model of track vehicle's air spring was constructed, in which the characters of rubber, the ply disposition, the fluid-solid coupling and the contact of top plate apron were taken into consideration. The calculation results show that; the function of the auxiliary chamber and the orifice can be neglected; but the effect of the auxiliary spring cannot be neglected. With the comparison of the horizontal reaction force between the calculation and the experiment, the relative error is within 6% which verified the model. By the study on the horizontal dynamic stiffness of air spring, it was found that:the air spring's horizontal stiffness is insensitive to the frequency and amplitude of the excitation; but it is sensitive to the balance position of vibration. The air spring's horizontal stiffness increases with the increment of the balance position and the increase rate becomes higher when the balance position becomes larger. This kind of nonlinear character of the air spring's horizontal stiffness is benefit for improving the horizontal ride comfort and stability of track vehicle.
Based on the nonlinear finite element method, a horizontal stiffness calculation model of track vehicle's air spring was constructed, in which the characters of rubber, the ply disposition, the fluid-solid coupling and the contact of top plate apron were taken into consideration. The calculation results show that; the function of the auxiliary chamber and the orifice can be neglected; but the effect of the auxiliary spring cannot be neglected. With the comparison of the horizontal reaction force between the calculation and the experiment, the relative error is within 6% which verified the model. By the study on the horizontal dynamic stiffness of air spring, it was found that:the air spring's horizontal stiffness is insensitive to the frequency and amplitude of the excitation; but it is sensitive to the balance position of vibration. The air spring's horizontal stiffness increases with the increment of the balance position and the increase rate becomes higher when the balance position becomes larger. This kind of nonlinear character of the air spring's horizontal stiffness is benefit for improving the horizontal ride comfort and stability of track vehicle.
2015, 34(10): 1536-1542.
doi: 10.13433/j.cnki.1003-8728.2015.1012
Abstract:
Usually a vertical motor uses hybrid axial magnetic bearings to carry out unloading and suspension control due to the structure of a permanent magnet and the influence of a hybrid axial magnetic bearing's control winding distribution on suspension performance, requiring the structural design according to bias and control magnetic field. This paper first analyzes the structure and working principles of a new single-side hybrid axial magnetic bearing used in the vertical motor. Then, according to the electromagnetic field measurement theory and the design method of the vertical motor, we present a parameter design method based on the bias/control magnetic field ratio restrictions. Finally we use the FEA software to verify the rationality and effectiveness of the parameter design method and to achieve the static/dynamic load and suspension stiffness.
Usually a vertical motor uses hybrid axial magnetic bearings to carry out unloading and suspension control due to the structure of a permanent magnet and the influence of a hybrid axial magnetic bearing's control winding distribution on suspension performance, requiring the structural design according to bias and control magnetic field. This paper first analyzes the structure and working principles of a new single-side hybrid axial magnetic bearing used in the vertical motor. Then, according to the electromagnetic field measurement theory and the design method of the vertical motor, we present a parameter design method based on the bias/control magnetic field ratio restrictions. Finally we use the FEA software to verify the rationality and effectiveness of the parameter design method and to achieve the static/dynamic load and suspension stiffness.
2015, 34(10): 1543-1546.
doi: 10.13433/j.cnki.1003-8728.2015.1013
Abstract:
A Meta-face Learning(MFL) localization algorithm for workpiece including free form surfaces is presented in this paper. With the method of image sparse representation based on dictionary learning with alternating iteration optimization, the transformation is updated from the measurement data to ideal geometric model with aligning the column vector of euclidean transformation matrix individually, and then the configuration of design frame is determined with respect to measurement frame. Two free form surfaces are used as examples to validate the effectiveness of the proposed algorithm and the comparative analysis with existing algorithms demonstrates the high computational efficiency and location accuracy of the algorithm.
A Meta-face Learning(MFL) localization algorithm for workpiece including free form surfaces is presented in this paper. With the method of image sparse representation based on dictionary learning with alternating iteration optimization, the transformation is updated from the measurement data to ideal geometric model with aligning the column vector of euclidean transformation matrix individually, and then the configuration of design frame is determined with respect to measurement frame. Two free form surfaces are used as examples to validate the effectiveness of the proposed algorithm and the comparative analysis with existing algorithms demonstrates the high computational efficiency and location accuracy of the algorithm.
2015, 34(10): 1547-1552.
doi: 10.13433/j.cnki.1003-8728.2015.1014
Abstract:
In order to improve the evaluation efficiency and accuracy of the line profile error, an evaluation method of the line profile error based on the minimum directed Hausdorff distance between the plane curves is proposed. The mathematical programming model and its linearization method for the minimum directed Hausdorff distance are presented. The results of the present method meet the minimum zone condition of the line profile error issued with national standard. The Projected-Polyhedron algorithm is applied to calculate the minimum distance between a point and a curve in the present method. Comparing with the results of two existed literatures, we verify the correctness and effectiveness of the present method. The numerical examples show that the results of the present method accords with the requirements of the minimum zone condition and the evaluation accuracy is very high.
In order to improve the evaluation efficiency and accuracy of the line profile error, an evaluation method of the line profile error based on the minimum directed Hausdorff distance between the plane curves is proposed. The mathematical programming model and its linearization method for the minimum directed Hausdorff distance are presented. The results of the present method meet the minimum zone condition of the line profile error issued with national standard. The Projected-Polyhedron algorithm is applied to calculate the minimum distance between a point and a curve in the present method. Comparing with the results of two existed literatures, we verify the correctness and effectiveness of the present method. The numerical examples show that the results of the present method accords with the requirements of the minimum zone condition and the evaluation accuracy is very high.
2015, 34(10): 1553-1559.
doi: 10.13433/j.cnki.1003-8728.2015.1015
Abstract:
A top-down design method of the tower crane boom with double lifting points was proposed to improve the design efficiency and achieve its lightweight. Constant strength of hoist boom's chord was set as constraint condition, and mathematical models of its jib structure were built based on solving maximum stress of the control section after solving rod's internal force with the force method. Rational geometry shape of jib structure and prismatic sectional dimension of chord were obtained by genetic algorithm optimization, then parameterized finite element model was built with APDL in ANSYS program to optimize variable section structure. Finally, a type of tower was designed forward and the design result was compared with existing tower, which shows that the top-down design method is reasonable, and the effect of lightweight is obvious.
A top-down design method of the tower crane boom with double lifting points was proposed to improve the design efficiency and achieve its lightweight. Constant strength of hoist boom's chord was set as constraint condition, and mathematical models of its jib structure were built based on solving maximum stress of the control section after solving rod's internal force with the force method. Rational geometry shape of jib structure and prismatic sectional dimension of chord were obtained by genetic algorithm optimization, then parameterized finite element model was built with APDL in ANSYS program to optimize variable section structure. Finally, a type of tower was designed forward and the design result was compared with existing tower, which shows that the top-down design method is reasonable, and the effect of lightweight is obvious.
2015, 34(10): 1560-1567.
doi: 10.13433/j.cnki.1003-8728.2015.1016
Abstract:
In analyzing and machining the mechanical parts whose profiles are defined by non-uniform rational B-splines(NURBS) curves, generally NURBS curves is piecewise constructed and represented in rational function form, the computation of curvature extremes is very complex and time-consuming. Therefore, a fast computation algorithm based on the micro-neighborhood analysis is proposed. The algorithm is consisted of the rough location stage and the precise search stage. In the rough location stage, the curvature variation type is deduced by analyzing the sampling points in the micro-neighborhood of the two endpoints of every knot section, then the amount of the curvature extremes and their single peak boundaries are determined. In the precise search stage, according to the analyzing the curvatures of the sampling points in the left and right micro-neighborhood of the midpoint of each search range, the fast binary search is done and the precise position of curvature extremes are located. The computation experiment demonstrated the good integrity, strong convergence and high computational efficiency of the present algorithm.
In analyzing and machining the mechanical parts whose profiles are defined by non-uniform rational B-splines(NURBS) curves, generally NURBS curves is piecewise constructed and represented in rational function form, the computation of curvature extremes is very complex and time-consuming. Therefore, a fast computation algorithm based on the micro-neighborhood analysis is proposed. The algorithm is consisted of the rough location stage and the precise search stage. In the rough location stage, the curvature variation type is deduced by analyzing the sampling points in the micro-neighborhood of the two endpoints of every knot section, then the amount of the curvature extremes and their single peak boundaries are determined. In the precise search stage, according to the analyzing the curvatures of the sampling points in the left and right micro-neighborhood of the midpoint of each search range, the fast binary search is done and the precise position of curvature extremes are located. The computation experiment demonstrated the good integrity, strong convergence and high computational efficiency of the present algorithm.
2015, 34(10): 1568-1573.
doi: 10.13433/j.cnki.1003-8728.2015.1017
Abstract:
The deflection value of gantry crane girder under rated load is the most important inspection index in the overall test. For large tonnage gantry crane, it is often very difficult to prepare the experimental weight on site of the overall test or even impossible to perform the test. In this study, the girder deflection curve equation considering the effects of the leg bending moment on the girder deflection is deduced with the concentrated load applying to the position of L/2、L/3、L/4 of the girder. The girder deflection value can be obtained under small load at the position of L/2、L/3、L/4 of the girde, and the actual inertia moment of the girder and the two side legs can be obtained. In this way, the deflection of the large tonnage gantry crane is predicted through the data of the three-position method in the small load test. The three-position small load test method provides a practical and effective method for the prediction of the girder deflection of large tonnage gantry structure.
The deflection value of gantry crane girder under rated load is the most important inspection index in the overall test. For large tonnage gantry crane, it is often very difficult to prepare the experimental weight on site of the overall test or even impossible to perform the test. In this study, the girder deflection curve equation considering the effects of the leg bending moment on the girder deflection is deduced with the concentrated load applying to the position of L/2、L/3、L/4 of the girder. The girder deflection value can be obtained under small load at the position of L/2、L/3、L/4 of the girde, and the actual inertia moment of the girder and the two side legs can be obtained. In this way, the deflection of the large tonnage gantry crane is predicted through the data of the three-position method in the small load test. The three-position small load test method provides a practical and effective method for the prediction of the girder deflection of large tonnage gantry structure.
2015, 34(10): 1574-1579.
doi: 10.13433/j.cnki.1003-8728.2015.1018
Abstract:
Based on the function transfer principle and frictional dissipation principle of a gear system, the characteristics of single tooth meshing and double tooth meshing during gear transmission are analyzed, the distribution coefficients of sliding velocity of a tooth surface and its normal positive pressure are solved and the mathematical model for computing instantaneous meshing dissipation power of the gear system is set up. Then taking the NGW type planetary gear reducer for example, we compute the instantaneous frictional dissipation power and transmission efficiency of each gear pair. The computational results show that the sliding friction dissipation power of the tooth surface is smaller in single tooth meshing areas; accordingly it is bigger in double tooth meshing areas. The sliding friction dissipation power and meshing transmission efficiency of the tooth surface have periodicity, variability and prodigious mutuality. The tooth surface friction dissipation power of external gear pair is greater than the friction dissipation power of internal gear pair. The phase relation of meshing state between each planet wheel and the central wheel has a great influence on the instantaneous frictional dissipation power and transmission efficiency and a certain influence on the transmission stability of planetary gear train.
Based on the function transfer principle and frictional dissipation principle of a gear system, the characteristics of single tooth meshing and double tooth meshing during gear transmission are analyzed, the distribution coefficients of sliding velocity of a tooth surface and its normal positive pressure are solved and the mathematical model for computing instantaneous meshing dissipation power of the gear system is set up. Then taking the NGW type planetary gear reducer for example, we compute the instantaneous frictional dissipation power and transmission efficiency of each gear pair. The computational results show that the sliding friction dissipation power of the tooth surface is smaller in single tooth meshing areas; accordingly it is bigger in double tooth meshing areas. The sliding friction dissipation power and meshing transmission efficiency of the tooth surface have periodicity, variability and prodigious mutuality. The tooth surface friction dissipation power of external gear pair is greater than the friction dissipation power of internal gear pair. The phase relation of meshing state between each planet wheel and the central wheel has a great influence on the instantaneous frictional dissipation power and transmission efficiency and a certain influence on the transmission stability of planetary gear train.
2015, 34(10): 1580-1583.
doi: 10.13433/j.cnki.1003-8728.2015.1019
Abstract:
Characteristic feature point methods and computational fluid dynamics(CFD) methods were applied to prediction or identification of the model parameter. The dynamic characteristic feature points were obtained with testing dynamic characteristics of the hydraulically damped rubber mount(HDRM) firstly and the complex stiffness of hydraulically damped rubber mount was derived from lumped parameters(LP) model by Fourier transform, and then the LP model was calculated by the relation developed between the feature points and the lumped parameters. The results were compared with experimental data,the work conducted in the paper demonstrates that the method for estimating the system parameters in the LP model of HDRM is effective.
Characteristic feature point methods and computational fluid dynamics(CFD) methods were applied to prediction or identification of the model parameter. The dynamic characteristic feature points were obtained with testing dynamic characteristics of the hydraulically damped rubber mount(HDRM) firstly and the complex stiffness of hydraulically damped rubber mount was derived from lumped parameters(LP) model by Fourier transform, and then the LP model was calculated by the relation developed between the feature points and the lumped parameters. The results were compared with experimental data,the work conducted in the paper demonstrates that the method for estimating the system parameters in the LP model of HDRM is effective.
2015, 34(10): 1584-1588.
doi: 10.13433/j.cnki.1003-8728.2015.1020
Abstract:
Canted coil spring stiffness is one of the most important indicators of its mechanical properties. Due to its special structure, there is not high efficiency and high precision instrument for stiffness measurement of canted coil spring. The canted coil spring stiffness measuring principle and related calculation method are proposed, and the corresponding test equipment is designed. In order to verify the feasibility of the present measuring scheme, a finite element model for canted coil spring based on ANSYS software is established, the simulations are carried out by considering geometric nonlinear and contact problem, and the experimental verification under quasi static loading are conducted on a tension and compression testing machine. The finite element simulation results and the experimental results show that the canted coil spring stiffness could be measured effectively with the present method, and the load-displacement curves for the canted coil spring could be efficiently obtained.
Canted coil spring stiffness is one of the most important indicators of its mechanical properties. Due to its special structure, there is not high efficiency and high precision instrument for stiffness measurement of canted coil spring. The canted coil spring stiffness measuring principle and related calculation method are proposed, and the corresponding test equipment is designed. In order to verify the feasibility of the present measuring scheme, a finite element model for canted coil spring based on ANSYS software is established, the simulations are carried out by considering geometric nonlinear and contact problem, and the experimental verification under quasi static loading are conducted on a tension and compression testing machine. The finite element simulation results and the experimental results show that the canted coil spring stiffness could be measured effectively with the present method, and the load-displacement curves for the canted coil spring could be efficiently obtained.
2015, 34(10): 1589-1593.
doi: 10.13433/j.cnki.1003-8728.2015.1021
Abstract:
Taking a segment of Lunnan-korla double line of crude oil X52 pipeline as the engineering background, considering that the pipeline is suspended accidentally and the pipeline segment is simplified as a deflected beam, we establish the large deformation analysis model of suspended pipeline system with the theory of Winkler elastic foundation and the tube-soil interaction bilinear model. In the analysis model, the geometric nonlinearity and the physical nonlinear longitudinal resistance of soil are considered and the buried area is treated as limited long beam. Through X52 pipe tensile test, the experiments for suspended pipeline and finite element simulation, the reliability of the finite element simulation method have been tested and verified. The security suspended length is calculated based on X52 pipe stress failure criterion and the maximum suspended length is also obtained based on failure criterion strain. The rationality of taken strain as the pipeline failure criterion is explained with studying the extreme stress and strain changing with the different suspended length.
Taking a segment of Lunnan-korla double line of crude oil X52 pipeline as the engineering background, considering that the pipeline is suspended accidentally and the pipeline segment is simplified as a deflected beam, we establish the large deformation analysis model of suspended pipeline system with the theory of Winkler elastic foundation and the tube-soil interaction bilinear model. In the analysis model, the geometric nonlinearity and the physical nonlinear longitudinal resistance of soil are considered and the buried area is treated as limited long beam. Through X52 pipe tensile test, the experiments for suspended pipeline and finite element simulation, the reliability of the finite element simulation method have been tested and verified. The security suspended length is calculated based on X52 pipe stress failure criterion and the maximum suspended length is also obtained based on failure criterion strain. The rationality of taken strain as the pipeline failure criterion is explained with studying the extreme stress and strain changing with the different suspended length.
2015, 34(10): 1594-1598.
doi: 10.13433/j.cnki.1003-8728.2015.1022
Abstract:
To objectively evaluate the layout aesthetic of man-machine interface form elements, the four aesthetic image indexes were extracted and quantified including balance, integrity, simplicity and uniformity. AHP method was used to calculate the weight of each image index, and the synthetic aesthetic calculation method of layout design was proposed. Man-machine interface form elements layout design of printer and copy machine was taken as an example to verify that the present method could help designer to select optimum scheme. Another example of man-machine layout design of gas water-heater was utilized to support the conclusion that the method could reflect the aesthetic level of man-machine interface form elements layout design more objectively and exactly so as to provide reference for users to select satisfactory solution.
To objectively evaluate the layout aesthetic of man-machine interface form elements, the four aesthetic image indexes were extracted and quantified including balance, integrity, simplicity and uniformity. AHP method was used to calculate the weight of each image index, and the synthetic aesthetic calculation method of layout design was proposed. Man-machine interface form elements layout design of printer and copy machine was taken as an example to verify that the present method could help designer to select optimum scheme. Another example of man-machine layout design of gas water-heater was utilized to support the conclusion that the method could reflect the aesthetic level of man-machine interface form elements layout design more objectively and exactly so as to provide reference for users to select satisfactory solution.
2015, 34(10): 1599-1603.
doi: 10.13433/j.cnki.1003-8728.2015.1023
Abstract:
As a new kind of self-adaptation time-frequency analysis approach, the local mean decomposition(LMD) shows a good application prospect in fault detection. According to the fact that the characteristics of vibration signal can be modulated when the crack fault exists on the gear hub of the reducer in an aero engine, we spropose a fault detection method based on LMD and support vector machine(SVM). Firstly, vibration sample data acquired through vibration tests performed in the aero engine. Then the fault information of fault gear hub was extracted by LMD to construct feature vectors. Eventually, taking the feature vectors as the input parameter of SVM, a fault detection model towards the target fault was successfully established. The analysis results demonstrate the effectiveness of the proposed method.
As a new kind of self-adaptation time-frequency analysis approach, the local mean decomposition(LMD) shows a good application prospect in fault detection. According to the fact that the characteristics of vibration signal can be modulated when the crack fault exists on the gear hub of the reducer in an aero engine, we spropose a fault detection method based on LMD and support vector machine(SVM). Firstly, vibration sample data acquired through vibration tests performed in the aero engine. Then the fault information of fault gear hub was extracted by LMD to construct feature vectors. Eventually, taking the feature vectors as the input parameter of SVM, a fault detection model towards the target fault was successfully established. The analysis results demonstrate the effectiveness of the proposed method.
2015, 34(10): 1604-1608.
doi: 10.13433/j.cnki.1003-8728.2015.1024
Abstract:
Two preparations of the PPDO(Poly p-dioxanone) degradable vascular stents, micro-imprint and 3D Printing was investigated. And each type samples' characters were studied, such as surface quality and radial strength. The results showed that, the surface quality of micro-imprint samples appears a group of average dates, inner surface Ra 0.429 and outside surface Ra 1.24, which is superior to the 3D Printing ones. And the diversity and controllability of the inner and outside surface quality, is more meet the clinical medicine requirement in the sections of inhibiting blood coagulation and steady placement. In addition, the intensity of radial strength of two kinds samples are higher than the clinical requirement(80 kPa), and the micro-imprint one is slightly higher than that of 3D Printing by 4%. This phenomenon was attributed to the forming temperature. In the micro-imprint process, the PPDO was fabricated in the viscous state, which made the thermal degradation of the polymer materials greatly reduced, better retention of mechanical properties and guarantee time of strength.
Two preparations of the PPDO(Poly p-dioxanone) degradable vascular stents, micro-imprint and 3D Printing was investigated. And each type samples' characters were studied, such as surface quality and radial strength. The results showed that, the surface quality of micro-imprint samples appears a group of average dates, inner surface Ra 0.429 and outside surface Ra 1.24, which is superior to the 3D Printing ones. And the diversity and controllability of the inner and outside surface quality, is more meet the clinical medicine requirement in the sections of inhibiting blood coagulation and steady placement. In addition, the intensity of radial strength of two kinds samples are higher than the clinical requirement(80 kPa), and the micro-imprint one is slightly higher than that of 3D Printing by 4%. This phenomenon was attributed to the forming temperature. In the micro-imprint process, the PPDO was fabricated in the viscous state, which made the thermal degradation of the polymer materials greatly reduced, better retention of mechanical properties and guarantee time of strength.
2015, 34(10): 1609-1613.
doi: 10.13433/j.cnki.1003-8728.2015.1025
Abstract:
The equipment mass and its relative position have a certain influence on the input admittance of the submarine deck. Research on the problem helps to reduce submarine's vibration and noise level, and enhance its stealth performance. Firstly the theoretical formulae describing concentrated mass on or outside the excitation point's influence on thin plate's input admittance are derived. Secondly, the relevant formulae are validated using ANSYS. In the end, the rules about equipment mass on or outside the excitation point's influence on submarine deck's input admittance are discussed using the theoretical formulae obtained. The results showed:increasing equipment mass on the excitation point significantly reduces input admittance; adjusting device location outside excitation point can reduce the input admittance to some extent.
The equipment mass and its relative position have a certain influence on the input admittance of the submarine deck. Research on the problem helps to reduce submarine's vibration and noise level, and enhance its stealth performance. Firstly the theoretical formulae describing concentrated mass on or outside the excitation point's influence on thin plate's input admittance are derived. Secondly, the relevant formulae are validated using ANSYS. In the end, the rules about equipment mass on or outside the excitation point's influence on submarine deck's input admittance are discussed using the theoretical formulae obtained. The results showed:increasing equipment mass on the excitation point significantly reduces input admittance; adjusting device location outside excitation point can reduce the input admittance to some extent.
2015, 34(10): 1614-1620.
doi: 10.13433/j.cnki.1003-8728.2015.1026
Abstract:
Because of the ultrasonic motor's inherent nonlinearity and strong coupling characteristics, it is difficult to establish the nonlinear mathematical model suitable for its control. The traditional PID control method has difficulties in obtaining satisfactory results. Using the nonlinear least squares method for the ultrasonic motor's frequency response data obtained through experiments for parameter identification, we establish the mathematical model of the ultrasonic motor. This paper proposes a novel fuzzy immune PID controller based on fuzzy rules, which can adjust the PID parameters online to adapt to different situations when the ultrasonic motor is running. The simulation results with MATLAB and the experimental results with TI's TMS320F2812 DSP indicate that the parameter identification method is more accurate and that the fuzzy immune PID controller for the real-time control of the ultrasonic motor has achieved good experimental results, good tracking performance and better dynamic and static performances.
Because of the ultrasonic motor's inherent nonlinearity and strong coupling characteristics, it is difficult to establish the nonlinear mathematical model suitable for its control. The traditional PID control method has difficulties in obtaining satisfactory results. Using the nonlinear least squares method for the ultrasonic motor's frequency response data obtained through experiments for parameter identification, we establish the mathematical model of the ultrasonic motor. This paper proposes a novel fuzzy immune PID controller based on fuzzy rules, which can adjust the PID parameters online to adapt to different situations when the ultrasonic motor is running. The simulation results with MATLAB and the experimental results with TI's TMS320F2812 DSP indicate that the parameter identification method is more accurate and that the fuzzy immune PID controller for the real-time control of the ultrasonic motor has achieved good experimental results, good tracking performance and better dynamic and static performances.
2015, 34(10): 1621-1625.
doi: 10.13433/j.cnki.1003-8728.2015.1027
Abstract:
The fluid resistance of a disk rotor rotating in a viscous flow field was analyzed based on the boundary layer theory. The friction resistance coefficient of the rotational rotor was obtained with the Prandtl-Schlichting formulas. The friction resistance per unit area was obtained with the Reynolds law and the formula for calculating the disk rotor's resistance moment was derived by computing its integral. The experiment on the disk rotor's fluid resistance was designed. The fluid resistance coefficients to be undetermined with the least squares method's curve fitting with the data were calculated with the formula, and the friction resistance moment calculation results agree well with the fluid resistance experimental data of all disk rotors that have different diameters, thicknesses and rotational speeds. The experimental results show that the friction resistance coefficient calculated with the formula derived and the fluid resistance coefficients for computing the disk rotor's resistance moment are feasible.
The fluid resistance of a disk rotor rotating in a viscous flow field was analyzed based on the boundary layer theory. The friction resistance coefficient of the rotational rotor was obtained with the Prandtl-Schlichting formulas. The friction resistance per unit area was obtained with the Reynolds law and the formula for calculating the disk rotor's resistance moment was derived by computing its integral. The experiment on the disk rotor's fluid resistance was designed. The fluid resistance coefficients to be undetermined with the least squares method's curve fitting with the data were calculated with the formula, and the friction resistance moment calculation results agree well with the fluid resistance experimental data of all disk rotors that have different diameters, thicknesses and rotational speeds. The experimental results show that the friction resistance coefficient calculated with the formula derived and the fluid resistance coefficients for computing the disk rotor's resistance moment are feasible.
2015, 34(10): 1626-1630.
doi: 10.13433/j.cnki.1003-8728.2015.1028
Abstract:
In order to explore the vibration coupling degree between the hanging power unit of an automobile and its suspension system, a mathematical model of the vibration coupling system containing the hanging power unit and the suspension system is established, and a modal coupling analysis method is proposed. As an example, the vibration coupling degree between the hanging power unit and the suspension system is calculated. The calculation results indicate that there is a high vibration coupling degree between them at the first modal and the seventh one.
In order to explore the vibration coupling degree between the hanging power unit of an automobile and its suspension system, a mathematical model of the vibration coupling system containing the hanging power unit and the suspension system is established, and a modal coupling analysis method is proposed. As an example, the vibration coupling degree between the hanging power unit and the suspension system is calculated. The calculation results indicate that there is a high vibration coupling degree between them at the first modal and the seventh one.
2015, 34(10): 1631-1635.
doi: 10.13433/j.cnki.1003-8728.2015.1029
Abstract:
Gust alleviation is the main research aspect on elastic aircraft. Combined rigid mode pitch control loop and elastic model control loop, the gust alleviation control schemes is proposed for a flying wing configuration elastic unmanned aerial vehicle(UAV). The low order output feedback controller is designed based on model reduction technique. The close loop system simulation results show that the wingtip acceleration maximum vibration range decreases 21.8% and acceleration maximum vibration range at center of gravity decreases 39% to the discrete gust. The continuous gust responses are alleviated effectively in all frequency ranges. Especially the wingtip load factor vibration range decreases 53% and acceleration vibration range at center of gravity decreases 45% at 6.024Hz. At the same time, the gust insensitivity calculation validates that the close loop system could keep insensitivity to gust.
Gust alleviation is the main research aspect on elastic aircraft. Combined rigid mode pitch control loop and elastic model control loop, the gust alleviation control schemes is proposed for a flying wing configuration elastic unmanned aerial vehicle(UAV). The low order output feedback controller is designed based on model reduction technique. The close loop system simulation results show that the wingtip acceleration maximum vibration range decreases 21.8% and acceleration maximum vibration range at center of gravity decreases 39% to the discrete gust. The continuous gust responses are alleviated effectively in all frequency ranges. Especially the wingtip load factor vibration range decreases 53% and acceleration vibration range at center of gravity decreases 45% at 6.024Hz. At the same time, the gust insensitivity calculation validates that the close loop system could keep insensitivity to gust.
2015, 34(10): 1636-1640.
doi: 10.13433/j.cnki.1003-8728.2015.1030
Abstract:
In order to reduce the pressure pulsation and improve the stability of the loading test system induced by suddenly closing valves, the control technology of high and low cycle fatigue experiment test platform for an aircraft engine fan blade was studied. By means of the computer simulation, the model for high-low cycle fatigue experiment of test patform based on MATLAB/SimHydraulics was established. On the basis of the system model, the simulation by changing the position and loading ways of the accumulator and altering the length and tube diameter of the front pipeline of accumulator and matching the system with different parameters was completed for the hydraulic test platform. It is found that the simulation of high-low cycle fatigue test rig has reached the expected purpose.
In order to reduce the pressure pulsation and improve the stability of the loading test system induced by suddenly closing valves, the control technology of high and low cycle fatigue experiment test platform for an aircraft engine fan blade was studied. By means of the computer simulation, the model for high-low cycle fatigue experiment of test patform based on MATLAB/SimHydraulics was established. On the basis of the system model, the simulation by changing the position and loading ways of the accumulator and altering the length and tube diameter of the front pipeline of accumulator and matching the system with different parameters was completed for the hydraulic test platform. It is found that the simulation of high-low cycle fatigue test rig has reached the expected purpose.
