Author Center
Editor Work
Peer Review
Editorial Entry
Email Alert
RSS2018 Vol. 37, No. 4
Display Method:
2018, 37(4): 493-500.
doi: 10.13433/j.cnki.1003-8728.2018.0401
PDF 1158KB
Abstract:
With the increasing of large-scaled wind turbines blade size, its flexibility is also growing up. It will be more prone to lead to larger structural deformation phenomena in the operation, nonlinear aeroelastic response, and different power performance and instability problems. To predict the nonlinear aeroelastic responses of large wind turbine, it makes sense to develop a new fluid-structure interaction model. A new fluid-structure interaction model including a nonlinear beam based on the geometrically exactly beam theory and an unsteady aerodynamic model based on vortex flow wake theory is applied to study Fluid-Structure Interaction characteristics of large size blade. For the effects of the flexible blade, weight-reduction techniques and increased size. Respectively, using the method that reduce the blade stiffness and reduce the quality. The effects of the large deformation and light weight on the coupling response were studied. The results show that the reduction of the stiffness will greatly increase the deformation and load of the blade, but the effect of the quality reduction on the blade deformation and load is not obvious. When the stiffness and quality are reduced at the same time, the deformation of the blade which is outside of the impeller plane will substantial increase, resulting in impeller power decrease. The influence of the size of rotor is also studied. And the results show the increased root stress and larger fluctuate of coupled response.
With the increasing of large-scaled wind turbines blade size, its flexibility is also growing up. It will be more prone to lead to larger structural deformation phenomena in the operation, nonlinear aeroelastic response, and different power performance and instability problems. To predict the nonlinear aeroelastic responses of large wind turbine, it makes sense to develop a new fluid-structure interaction model. A new fluid-structure interaction model including a nonlinear beam based on the geometrically exactly beam theory and an unsteady aerodynamic model based on vortex flow wake theory is applied to study Fluid-Structure Interaction characteristics of large size blade. For the effects of the flexible blade, weight-reduction techniques and increased size. Respectively, using the method that reduce the blade stiffness and reduce the quality. The effects of the large deformation and light weight on the coupling response were studied. The results show that the reduction of the stiffness will greatly increase the deformation and load of the blade, but the effect of the quality reduction on the blade deformation and load is not obvious. When the stiffness and quality are reduced at the same time, the deformation of the blade which is outside of the impeller plane will substantial increase, resulting in impeller power decrease. The influence of the size of rotor is also studied. And the results show the increased root stress and larger fluctuate of coupled response.
2018, 37(4): 501-504.
doi: 10.13433/j.cnki.1003-8728.2018.0402
Abstract:
Structural reliability boundary calculation method is proposed based on the Second order reliability method(SORM) and the envelope surface. Rotating paraboloids were applied as the interior and the exterior envelope surface of the limit state surface in most probable failure region, and the failure probability of envelope surface was calculated to determine the structural reliability boundary.The feasibility and accuracy of this method was verified by two numerical examples. The results obtained by this method agree well with those by the Monte Carlo method, and the relative error of this method is small.
Structural reliability boundary calculation method is proposed based on the Second order reliability method(SORM) and the envelope surface. Rotating paraboloids were applied as the interior and the exterior envelope surface of the limit state surface in most probable failure region, and the failure probability of envelope surface was calculated to determine the structural reliability boundary.The feasibility and accuracy of this method was verified by two numerical examples. The results obtained by this method agree well with those by the Monte Carlo method, and the relative error of this method is small.
2018, 37(4): 505-509.
doi: 10.13433/j.cnki.1003-8728.2018.0403
Abstract:
In order to improve the efficiency and quality of lithium battery slurry preparation, on the basis of the existing process plan, this paper designs a vacuum continuous pulping process which can realize from the raw material pretreatment process of lithium ion power battery to the coating process by automatic. Using the method of geometric weighted AHP to build the transfer matrix method, the paper carries out the reliability analysis to evaluate the scheme of three kinds of pulping process and the design of vacuum continuous pulping. The results show that:the key factors influencing the quality of slurry are the degree of automation of the pulping system, the process of mixing and dispersing and the pretreatment of raw materials. comparing with the existing technology, the process has some advantages. Based on the conclusion of geometric weighted AHP method, the key equipment of vacuum continuous pulping process is researched, and finally the schematic diagram of vacuum slurry preparation system is obtained.
In order to improve the efficiency and quality of lithium battery slurry preparation, on the basis of the existing process plan, this paper designs a vacuum continuous pulping process which can realize from the raw material pretreatment process of lithium ion power battery to the coating process by automatic. Using the method of geometric weighted AHP to build the transfer matrix method, the paper carries out the reliability analysis to evaluate the scheme of three kinds of pulping process and the design of vacuum continuous pulping. The results show that:the key factors influencing the quality of slurry are the degree of automation of the pulping system, the process of mixing and dispersing and the pretreatment of raw materials. comparing with the existing technology, the process has some advantages. Based on the conclusion of geometric weighted AHP method, the key equipment of vacuum continuous pulping process is researched, and finally the schematic diagram of vacuum slurry preparation system is obtained.
2018, 37(4): 510-518.
doi: 10.13433/j.cnki.1003-8728.2018.0404
Abstract:
3-RPUU is a six degree of freedom parallel mechanism (PM) with 3 limbs involving UU chains, and the singularity of this PM is analyzed based on instantaneous twists. Firstly, by introducing the geography parameters, the inputs of the active joints and the pose parameters of the mobile platform, the kinematic screw system of all the limbs is given. Secondly, using closed vector method and incorporating the geometrical characteristic of each joint, the inverse position solutions and the orientation angle of the rotational axes are calculated, and the instantaneous twists are determined. At last, according to the instantaneous twists, the discriminator of singularity can be obtained and two examples are given to verify the practicality.
3-RPUU is a six degree of freedom parallel mechanism (PM) with 3 limbs involving UU chains, and the singularity of this PM is analyzed based on instantaneous twists. Firstly, by introducing the geography parameters, the inputs of the active joints and the pose parameters of the mobile platform, the kinematic screw system of all the limbs is given. Secondly, using closed vector method and incorporating the geometrical characteristic of each joint, the inverse position solutions and the orientation angle of the rotational axes are calculated, and the instantaneous twists are determined. At last, according to the instantaneous twists, the discriminator of singularity can be obtained and two examples are given to verify the practicality.
2018, 37(4): 519-524.
doi: 10.13433/j.cnki.1003-8728.2018.0405
Abstract:
To study the influence of the wedge structural design on the aerodynamic and aeroacoustic performance of engine cooling fans, a series of numerical simulations are carried out with CFD (Computational Fluid Dynamics)/CAA (Computational Aerodynamic Acoustic) distributed coupling method. The flow field and acoustic field of two cooling fans without and with wedge structures on its suction surfaces are analyzed under the rated condition. The results show that the aerodynamic performance of cooling fans is vulnerable to the wedge structures. But noise performance is obviously influenced. The noise values at the inlet and outlet of the cooling fan with wedge structures are decreased by 8.8% and 8.9% respectively while the volume flow increases slightly. Through specific analyses of flow field and acoustic field of two cooling fans, it can be concluded that the wedge structures act as "vortex flow generators" on the suction surfaces. They advance the transition from laminar flow to turbulent. Thus the vortex noise induced by premature airflow separation around the blade surface is reduced obviously, which lead to a definite decline in the overall noise.
To study the influence of the wedge structural design on the aerodynamic and aeroacoustic performance of engine cooling fans, a series of numerical simulations are carried out with CFD (Computational Fluid Dynamics)/CAA (Computational Aerodynamic Acoustic) distributed coupling method. The flow field and acoustic field of two cooling fans without and with wedge structures on its suction surfaces are analyzed under the rated condition. The results show that the aerodynamic performance of cooling fans is vulnerable to the wedge structures. But noise performance is obviously influenced. The noise values at the inlet and outlet of the cooling fan with wedge structures are decreased by 8.8% and 8.9% respectively while the volume flow increases slightly. Through specific analyses of flow field and acoustic field of two cooling fans, it can be concluded that the wedge structures act as "vortex flow generators" on the suction surfaces. They advance the transition from laminar flow to turbulent. Thus the vortex noise induced by premature airflow separation around the blade surface is reduced obviously, which lead to a definite decline in the overall noise.
2018, 37(4): 525-531.
doi: 10.13433/j.cnki.1003-8728.2018.0406
Abstract:
In the legged robot operation, the phenomenon of leg loss often occurs due to environmental factors. Single-leg missing robots will not be able to continue walking or even standing in accordance with the original control. In order to improve the sustainable ability of the robot to cope with the complicated working environment, a four-legged robot control method is proposed to solve the problem by adjusting the pendulum joint and increasing the stabilization phase without additional equipment. After calculating the static analysis of the damaged robot, the optimal solution of the rotation angle of the side pendulum is 21°. According to the comparison of the adjacent series of angle values, the roll angle of the robot is always changed between -2° to 2° when the angle of the pendulum joint is 21°, and the amplitude of the roll angle of the robot decreases by 10.8% after 16 cycles, which verifies the effectiveness of the proposed control method.
In the legged robot operation, the phenomenon of leg loss often occurs due to environmental factors. Single-leg missing robots will not be able to continue walking or even standing in accordance with the original control. In order to improve the sustainable ability of the robot to cope with the complicated working environment, a four-legged robot control method is proposed to solve the problem by adjusting the pendulum joint and increasing the stabilization phase without additional equipment. After calculating the static analysis of the damaged robot, the optimal solution of the rotation angle of the side pendulum is 21°. According to the comparison of the adjacent series of angle values, the roll angle of the robot is always changed between -2° to 2° when the angle of the pendulum joint is 21°, and the amplitude of the roll angle of the robot decreases by 10.8% after 16 cycles, which verifies the effectiveness of the proposed control method.
2018, 37(4): 532-536.
doi: 10.13433/j.cnki.1003-8728.2018.0407
Abstract:
In order to solve the problem that conventional electro-mechanical converter of 2D valve had deficiency of complicated magnetic circuit and structure, a single-phase excited magnetic circuit with axial asymmetrical topology is proposed, and based on that a novel permanent magnet torque motor is developed. Firstly the equation of torque-angle characteristics is derived via analytical method, then a finite element analysis model is built to describe magnetic field distribution, and therefore numerical results of torque-angle characteristics are obtained. Prototype motor is designed and fabricated based on numerical simulation. The experimental rig is built up to study torque-angle characteristics. The experimental results agreed well with simulations, which indicates prototype motor has large magnetic torque and its torque-angle characteristic is close to linear relationship whose amplitude increases with excited current. The proposed motor is appropriate to be electro-mechanical converter of 2D three-way valve and other similar control components.
In order to solve the problem that conventional electro-mechanical converter of 2D valve had deficiency of complicated magnetic circuit and structure, a single-phase excited magnetic circuit with axial asymmetrical topology is proposed, and based on that a novel permanent magnet torque motor is developed. Firstly the equation of torque-angle characteristics is derived via analytical method, then a finite element analysis model is built to describe magnetic field distribution, and therefore numerical results of torque-angle characteristics are obtained. Prototype motor is designed and fabricated based on numerical simulation. The experimental rig is built up to study torque-angle characteristics. The experimental results agreed well with simulations, which indicates prototype motor has large magnetic torque and its torque-angle characteristic is close to linear relationship whose amplitude increases with excited current. The proposed motor is appropriate to be electro-mechanical converter of 2D three-way valve and other similar control components.
2018, 37(4): 537-544.
doi: 10.13433/j.cnki.1003-8728.2018.0408
Abstract:
In view of the low SNR (Signal Noise Ratio) of the early fault signals of the high pressure diaphragm pump check valve, it is difficult to extract the fault feature. In this paper, an early fault diagnosis method based on adaptive stochastic resonance and DEMD (Differential Empirical Mode Decomposition) is proposed. First of all, the original signal is processed, and the compression ratio is set for variable scale processing. Then, SNR is used as the adaptive degree function, and the PSO (Particle Swarm Optimization) algorithm is used to optimize the parameters of SR (Stochastic Resonance) system, the optimized parameters and the processed signals are input into the SR system. Finally, the signal output from the system is decomposed by DEMD algorithm; the components are analyzed by spectrum analysis, and the component synthesis with characteristic frequency is selected to carry out envelope analysis to extract the fault feature information. The results of simulation analysis and engineering experiment show the method can better extract the early fault feature information of the check valve.
In view of the low SNR (Signal Noise Ratio) of the early fault signals of the high pressure diaphragm pump check valve, it is difficult to extract the fault feature. In this paper, an early fault diagnosis method based on adaptive stochastic resonance and DEMD (Differential Empirical Mode Decomposition) is proposed. First of all, the original signal is processed, and the compression ratio is set for variable scale processing. Then, SNR is used as the adaptive degree function, and the PSO (Particle Swarm Optimization) algorithm is used to optimize the parameters of SR (Stochastic Resonance) system, the optimized parameters and the processed signals are input into the SR system. Finally, the signal output from the system is decomposed by DEMD algorithm; the components are analyzed by spectrum analysis, and the component synthesis with characteristic frequency is selected to carry out envelope analysis to extract the fault feature information. The results of simulation analysis and engineering experiment show the method can better extract the early fault feature information of the check valve.
2018, 37(4): 545-552.
doi: 10.13433/j.cnki.1003-8728.2018.0409
Abstract:
Finding the crack location of blades has the great significance in reducing maintenance cycle and extending the working life. In this paper, a crack location method via the nonlinearity estimation of vibration response is proposed for blades under the high frequency excitation. The definition of nonlinearity estimation and the corresponding calculation method are given for this method. First, a matrix form signal is composed of the nonlinear vibration signals which are collected at the multi-position points of the blades. Then, its linear approximation is obtained by the proper orthogonal decomposition, and the error is quantified between the matrix form signal and its linear approximation. The values of nonlinearity estimation for vibration response signals on each positions of the blade are calculated. Second, the values of nonlinearity estimation for blades with and without a crack are compared under the same excitation inputs, and the maximum absolute error of the values is found to identify the location of the crack. The finite element models of blades with and without a crack are established, and the effectiveness of the method is demonstrated and verified under various excitation frequencies.
Finding the crack location of blades has the great significance in reducing maintenance cycle and extending the working life. In this paper, a crack location method via the nonlinearity estimation of vibration response is proposed for blades under the high frequency excitation. The definition of nonlinearity estimation and the corresponding calculation method are given for this method. First, a matrix form signal is composed of the nonlinear vibration signals which are collected at the multi-position points of the blades. Then, its linear approximation is obtained by the proper orthogonal decomposition, and the error is quantified between the matrix form signal and its linear approximation. The values of nonlinearity estimation for vibration response signals on each positions of the blade are calculated. Second, the values of nonlinearity estimation for blades with and without a crack are compared under the same excitation inputs, and the maximum absolute error of the values is found to identify the location of the crack. The finite element models of blades with and without a crack are established, and the effectiveness of the method is demonstrated and verified under various excitation frequencies.
2018, 37(4): 553-559.
doi: 10.13433/j.cnki.1003-8728.2018.0410
Abstract:
To extend the power of the lower limb and complete the human-machine tasks under the specific environment, a wearable power-assisted lower extremity exoskeleton has been designed and developed as a coherent robot. Based on biomechanical characteristics of human walking, the paper describes the mechanism design of the exoskeleton robot and the kinematics of the robot is analysed. According to simulation in ADAMS, the joints of the exoskeleton and ranges of actuators are matched and optimized, all which could achieve the representative of human movement-squat. Walking margins are reserved for the power-assisted robot on ranges of motion. Therefore, the experimental results of the virtual prototype show that the proposed design for the exoskeleton is feasible and effective.
To extend the power of the lower limb and complete the human-machine tasks under the specific environment, a wearable power-assisted lower extremity exoskeleton has been designed and developed as a coherent robot. Based on biomechanical characteristics of human walking, the paper describes the mechanism design of the exoskeleton robot and the kinematics of the robot is analysed. According to simulation in ADAMS, the joints of the exoskeleton and ranges of actuators are matched and optimized, all which could achieve the representative of human movement-squat. Walking margins are reserved for the power-assisted robot on ranges of motion. Therefore, the experimental results of the virtual prototype show that the proposed design for the exoskeleton is feasible and effective.
2018, 37(4): 560-567.
doi: 10.13433/j.cnki.1003-8728.2018.0411
Abstract:
A mechanistic based cutting force model was proposed for predicting forces in milling of carbon fiber reinforced polymer composite (CFRP), in which the effects of the cutting edges on the tool periphery and bottom were both considered. Through experiments, the force contributions by peripheral edges and bottom edges were recognized and analyzed. The influences of the instantaneous chip thickness, fiber cutting angle and cutting speed on the specific cutting forces were recognized and modeled based on BP neural network. The proposed approach shows better agreement with the experimental. The result shows the prediction accuracy of force can be improved when the bottom of cutter blade was incorporated in the model. The feasibility of BP neural network for cutting force modeling was also verified.
A mechanistic based cutting force model was proposed for predicting forces in milling of carbon fiber reinforced polymer composite (CFRP), in which the effects of the cutting edges on the tool periphery and bottom were both considered. Through experiments, the force contributions by peripheral edges and bottom edges were recognized and analyzed. The influences of the instantaneous chip thickness, fiber cutting angle and cutting speed on the specific cutting forces were recognized and modeled based on BP neural network. The proposed approach shows better agreement with the experimental. The result shows the prediction accuracy of force can be improved when the bottom of cutter blade was incorporated in the model. The feasibility of BP neural network for cutting force modeling was also verified.
2018, 37(4): 568-574.
doi: 10.13433/j.cnki.1003-8728.2018.0412
Abstract:
In machining for mold structural requirements become more complex, resulting in the existence of a large number of grooves and convex concave structure in the free type mold surface, prone to severe wear and galling cracking. The stress characteristics of different positions of the die are different, adopting the whole milling process of insert type module after splicing. However, the splicing is mainly caused by the milling force mutation, which leads to the problem of high tool wear and low precision. In this paper, the forming mechanism of the surface of the convex surface splicing die is formed by the tool of the ball end milling, and the contact relationship between the cutting tool and the workpiece in the milling process is analyzed; The hardened steel Cr12MoV convex surface splicing die experiment of ball end milling cutter of different hardness as the object, to reveal the effects of depth of cut, cutting speed, feed per tooth and milling directions on milling force mutation of splicing area. The orthogonal experiment was carried out with the minimum milling force mutation as the target, then the primary and secondary influence law and the optimal parameter combination were obtained.
In machining for mold structural requirements become more complex, resulting in the existence of a large number of grooves and convex concave structure in the free type mold surface, prone to severe wear and galling cracking. The stress characteristics of different positions of the die are different, adopting the whole milling process of insert type module after splicing. However, the splicing is mainly caused by the milling force mutation, which leads to the problem of high tool wear and low precision. In this paper, the forming mechanism of the surface of the convex surface splicing die is formed by the tool of the ball end milling, and the contact relationship between the cutting tool and the workpiece in the milling process is analyzed; The hardened steel Cr12MoV convex surface splicing die experiment of ball end milling cutter of different hardness as the object, to reveal the effects of depth of cut, cutting speed, feed per tooth and milling directions on milling force mutation of splicing area. The orthogonal experiment was carried out with the minimum milling force mutation as the target, then the primary and secondary influence law and the optimal parameter combination were obtained.
2018, 37(4): 575-580.
doi: 10.13433/j.cnki.1003-8728.2018.0413
Abstract:
Industrial robot vision system need to objectively evaluate image quality in calibration process. While the reference image is known, the existing image quality assessment (IQA) method cannot effectively characterize the local structure difference, thus it is difficult to fully consider the impact of pixel level difference. Therefore, the full reference IQA method based on the visual saliency is proposed in this paper. To be specific, the difference characterization method is designed, in which the phase congruency and gradient map are used to describe the differences in local structure. Thus, the IQA method based on the visual saliency is proposed, in which the pixel level difference weights are assigned to the different local structure of image in order to improve the performance. The results show that the present method can achieve the quality evaluation scores in three standard databases.
Industrial robot vision system need to objectively evaluate image quality in calibration process. While the reference image is known, the existing image quality assessment (IQA) method cannot effectively characterize the local structure difference, thus it is difficult to fully consider the impact of pixel level difference. Therefore, the full reference IQA method based on the visual saliency is proposed in this paper. To be specific, the difference characterization method is designed, in which the phase congruency and gradient map are used to describe the differences in local structure. Thus, the IQA method based on the visual saliency is proposed, in which the pixel level difference weights are assigned to the different local structure of image in order to improve the performance. The results show that the present method can achieve the quality evaluation scores in three standard databases.
2018, 37(4): 581-585.
doi: 10.13433/j.cnki.1003-8728.2018.0414
Abstract:
To reveal the forming characteristics and failure mechanism of sandwich structure self-piercing riveted(SPR) joint with nickel foam, the SPR joints with AA5052 aluminum alloy as substrate and nickel foam as inter-layer were manufactured. The forming characteristics of sandwich structure SPR joint was systematically studied by combining theoretical analysis with microscopic observation. The tensile-shear tests were carried out to study the static failure load and failure displacement of the joint. The failure mechanism about the joint was simultaneously investigated. The results indicated that rivet flaring of the joint has increased by using foam inter-layer, the distribution of stress was also improved. A solid self-lubricating physical absorption film between the riveted interface was formed during the connection process, which can improve the corrosion resistance of the joint. The static failure load of the joint has increased by 8.9% due to the use of the nickel foam inter-layer of 1 mm thickness. The tensile strength of joint decreased with the increasing of thickness of the form inter-layer. The sandwich structure SPR joint with nickel foam inter-layer failed by the rivet being pulled out from the lower sheet, the upper sheet was mainly subjected to tensile load, while the lower plate was subjected to compression load.
To reveal the forming characteristics and failure mechanism of sandwich structure self-piercing riveted(SPR) joint with nickel foam, the SPR joints with AA5052 aluminum alloy as substrate and nickel foam as inter-layer were manufactured. The forming characteristics of sandwich structure SPR joint was systematically studied by combining theoretical analysis with microscopic observation. The tensile-shear tests were carried out to study the static failure load and failure displacement of the joint. The failure mechanism about the joint was simultaneously investigated. The results indicated that rivet flaring of the joint has increased by using foam inter-layer, the distribution of stress was also improved. A solid self-lubricating physical absorption film between the riveted interface was formed during the connection process, which can improve the corrosion resistance of the joint. The static failure load of the joint has increased by 8.9% due to the use of the nickel foam inter-layer of 1 mm thickness. The tensile strength of joint decreased with the increasing of thickness of the form inter-layer. The sandwich structure SPR joint with nickel foam inter-layer failed by the rivet being pulled out from the lower sheet, the upper sheet was mainly subjected to tensile load, while the lower plate was subjected to compression load.
2018, 37(4): 586-591.
doi: 10.13433/j.cnki.1003-8728.2018.0415
Abstract:
In view of the effect of the abrasive arraying forms on the grinding efficiency and performance, the pressurized internal-cooling grinding wheels with random or ordered abrasive are designed and prepared. Based on the surface morphology detection technology and image identification technology, the 3D finite element model for grinding superalloy GH4169 is established. The grinding experiments of superalloy GH4169 are performed by adopting the prepared wheels, the effects of the abrasive arraying forms on the grinding performance are revealed, grinding force, temperature, machined surface roughness and surface topography are studied. The results show that:compared with the wheel with random abrasive, wheel with ordered abrasive leads to better machined surface quality, smaller grinding force, lower grinding temperature and surface roughness, moreover cleaner surface morphology.
In view of the effect of the abrasive arraying forms on the grinding efficiency and performance, the pressurized internal-cooling grinding wheels with random or ordered abrasive are designed and prepared. Based on the surface morphology detection technology and image identification technology, the 3D finite element model for grinding superalloy GH4169 is established. The grinding experiments of superalloy GH4169 are performed by adopting the prepared wheels, the effects of the abrasive arraying forms on the grinding performance are revealed, grinding force, temperature, machined surface roughness and surface topography are studied. The results show that:compared with the wheel with random abrasive, wheel with ordered abrasive leads to better machined surface quality, smaller grinding force, lower grinding temperature and surface roughness, moreover cleaner surface morphology.
2018, 37(4): 592-598.
doi: 10.13433/j.cnki.1003-8728.2018.0416
Abstract:
The uniformity of electrodes thickness is one of the most important factors that affect the capacity, cycle life and safety of lithium ion battery. Aiming at inferior thickness uniformity and narrow rolling width, the finite element models of the two-high mill and the four-high mill are established, and the accuracy of the finite element model is verified by experiments. The four-high mill rolls system model which is equivalent to the two-high mill Ø500×500 in the same rolling condition is also established, and the influence law of the change of working roll diameter, supporting roll diameter, roll length of four-high mill and bending force on the electrodes thickness uniformity is analyzed. The results show that, the four-high mill instead of two-high mill has the feasibility of rolling power lithium ion battery electrodes. With the increase of four-high mill working roll diameter and supporting roll diameter, electrodes thickness uniformity along the width direction is improved. With the increase of four-high mill roll length, electrodes thickness uniformity along the width direction is decreased. With the increase of working roll bending force, electrodes thickness uniformity along the width direction and rolling width are improved, it can improve the problem that electrodes rolling width is too narrow in actual production.
The uniformity of electrodes thickness is one of the most important factors that affect the capacity, cycle life and safety of lithium ion battery. Aiming at inferior thickness uniformity and narrow rolling width, the finite element models of the two-high mill and the four-high mill are established, and the accuracy of the finite element model is verified by experiments. The four-high mill rolls system model which is equivalent to the two-high mill Ø500×500 in the same rolling condition is also established, and the influence law of the change of working roll diameter, supporting roll diameter, roll length of four-high mill and bending force on the electrodes thickness uniformity is analyzed. The results show that, the four-high mill instead of two-high mill has the feasibility of rolling power lithium ion battery electrodes. With the increase of four-high mill working roll diameter and supporting roll diameter, electrodes thickness uniformity along the width direction is improved. With the increase of four-high mill roll length, electrodes thickness uniformity along the width direction is decreased. With the increase of working roll bending force, electrodes thickness uniformity along the width direction and rolling width are improved, it can improve the problem that electrodes rolling width is too narrow in actual production.
2018, 37(4): 599-606.
doi: 10.13433/j.cnki.1003-8728.2018.0417
Abstract:
To carry out the three-dimensional motion simulation of a modular manipulator and its real-time online control, a fast and efficient method of constructing an open 3D manipulator virtual simulation platform was presented. The method was carried out by using as an environment platform the MATLAB software that has powerful data processing capacity. The functions of professional solid modeling software of SolidWorks, the practical modeling functions of robotic toolbox and the MATLAB GUI interaction design and 3D animation and display technology of MATLAB were applied to the construction of a good visualization, the powerful function of the input and output and the realistic and detailed model of the 3D manipulator virtual simulation platform. Taking the Schunk six-DOF modular manipulator as example, the implementation procedures of this method were described in detail, thus realizing the high-level open and 3D manipulator virtual simulation platform with realistic visualization. Some of simulation graphs are displayed. The test results show that this method can quickly construct the 3D virtual simulation platform with good usability and high maneuverability, which can meet the needs of scientific research and teaching. The test results also prove the effectiveness of our method.
To carry out the three-dimensional motion simulation of a modular manipulator and its real-time online control, a fast and efficient method of constructing an open 3D manipulator virtual simulation platform was presented. The method was carried out by using as an environment platform the MATLAB software that has powerful data processing capacity. The functions of professional solid modeling software of SolidWorks, the practical modeling functions of robotic toolbox and the MATLAB GUI interaction design and 3D animation and display technology of MATLAB were applied to the construction of a good visualization, the powerful function of the input and output and the realistic and detailed model of the 3D manipulator virtual simulation platform. Taking the Schunk six-DOF modular manipulator as example, the implementation procedures of this method were described in detail, thus realizing the high-level open and 3D manipulator virtual simulation platform with realistic visualization. Some of simulation graphs are displayed. The test results show that this method can quickly construct the 3D virtual simulation platform with good usability and high maneuverability, which can meet the needs of scientific research and teaching. The test results also prove the effectiveness of our method.
2018, 37(4): 607-613.
doi: 10.13433/j.cnki.1003-8728.2018.0418
Abstract:
Aiming at the problems that the stochastic resonance(SR) processing the signal in the bearing fault diagnosis needs to meet the condition of small parameters (frequency, amplitude and noise intensity are far less than 1) and the fault features of bearing were difficult to extract, a method of the self-adaptive re-scaling stochastic resonance based on genetic algorithm(GA) and the ensemble local mean decomposition (ELMD) was proposed. Firstly, the measured signal is compressed according to certain frequency, making it meet the requirements of small parameter of stochastic resonance. Secondly, the structure-parameter of the scale-transformation stochastic resonance system is optimized by genetic algorithm. Finally, the output signal of stochastic resonance is decomposed by ELMD, through each frequency spectrum of component of the PF, the character frequency of rolling bearing are looked for. Through experimental analysis of the measured bearing fault signal, the results show that the proposed method can be effectively used in bearing fault diagnosis.
Aiming at the problems that the stochastic resonance(SR) processing the signal in the bearing fault diagnosis needs to meet the condition of small parameters (frequency, amplitude and noise intensity are far less than 1) and the fault features of bearing were difficult to extract, a method of the self-adaptive re-scaling stochastic resonance based on genetic algorithm(GA) and the ensemble local mean decomposition (ELMD) was proposed. Firstly, the measured signal is compressed according to certain frequency, making it meet the requirements of small parameter of stochastic resonance. Secondly, the structure-parameter of the scale-transformation stochastic resonance system is optimized by genetic algorithm. Finally, the output signal of stochastic resonance is decomposed by ELMD, through each frequency spectrum of component of the PF, the character frequency of rolling bearing are looked for. Through experimental analysis of the measured bearing fault signal, the results show that the proposed method can be effectively used in bearing fault diagnosis.
2018, 37(4): 614-622.
doi: 10.13433/j.cnki.1003-8728.2018.0419
Abstract:
A hybrid control model of an automobile's electronic stability program (ESP) was established to control its rollover and instability under extreme steering conditions with differential braking. To improve the control effect, an anti-lock braking (ABS) system was integrated. In order to prevent the conflict between ESP and ABS, a differential brake coordinator was designed to meet the control requirements of each system. Finally, we carried out the double-lane and fish hook simulations of the automobile equipped with ESP and ABS systems. The simulation results show that the ESP system with the hybrid control model was effective for controlling the rollover and instability of the automobile; therefore, its operating stability and driving safety were greatly improved.
A hybrid control model of an automobile's electronic stability program (ESP) was established to control its rollover and instability under extreme steering conditions with differential braking. To improve the control effect, an anti-lock braking (ABS) system was integrated. In order to prevent the conflict between ESP and ABS, a differential brake coordinator was designed to meet the control requirements of each system. Finally, we carried out the double-lane and fish hook simulations of the automobile equipped with ESP and ABS systems. The simulation results show that the ESP system with the hybrid control model was effective for controlling the rollover and instability of the automobile; therefore, its operating stability and driving safety were greatly improved.
A Rollover Warning Algorithm for Improving Steering Wheel Angle TTR and Dynamic Mass Centroid Height
2018, 37(4): 623-628.
doi: 10.13433/j.cnki.1003-8728.2018.0420
Abstract:
In order to eliminate the influence of the lag between steering wheel angle and vehicle dynamic response and to change the mass centroid height to improve the accuracy of the traditional Time to Rollover warning algorithms, the steering wheel angle TTR and dynamic mass centroid height warning algorithm is proposed. The three degrees-of-freedom dynamic model is set up by using the Maple software to solve the relationship between the steering wheel angle and various motion parameters, and then the mathematical model is imported into the dynamics software TruckSim to carry out the simulation under several typical working conditions. We compare the motion parameters of the traditional algorithm with the improved algorithm for steering wheel angle TTR and contrast the simulated mass centroid height with the theoretical calculation results. The simulation results show that the dynamic model's calculation results are accurate and that the improved rollover warning algorithm is superior to the traditional algorithm, can effectively reduce the lag between steering wheel angle and vehicle dynamic response and give warning ahead of time.
In order to eliminate the influence of the lag between steering wheel angle and vehicle dynamic response and to change the mass centroid height to improve the accuracy of the traditional Time to Rollover warning algorithms, the steering wheel angle TTR and dynamic mass centroid height warning algorithm is proposed. The three degrees-of-freedom dynamic model is set up by using the Maple software to solve the relationship between the steering wheel angle and various motion parameters, and then the mathematical model is imported into the dynamics software TruckSim to carry out the simulation under several typical working conditions. We compare the motion parameters of the traditional algorithm with the improved algorithm for steering wheel angle TTR and contrast the simulated mass centroid height with the theoretical calculation results. The simulation results show that the dynamic model's calculation results are accurate and that the improved rollover warning algorithm is superior to the traditional algorithm, can effectively reduce the lag between steering wheel angle and vehicle dynamic response and give warning ahead of time.
2018, 37(4): 629-634.
doi: 10.13433/j.cnki.1003-8728.2018.0421
Abstract:
In this paper, the multi-objective particle swarm optimization (MOPSO) algorithm was used to optimized the transmission system parameters of vehicle. Firstly, according to the structure of the target vehicle, the whole vehicle model is built and validated by vehicle bench experiment. Secondly, the vehicle powertrain parameters are taken as design variables and the vehicle power and economy are taken as the optimization targets, a multi-objective optimization model of the vehicle is built. The transmission parameters are optimized by the multi-objective particle swarm algorithm. the Pareto optimal solution set is obtained by calculating the optimization parameters. Finally, the optimal transmission parameters are determined by the multiple attribute decision making method based on information entropy. Finally, the optimal transmission parameters were determined by the multiple attribute decision making method based on information entropy. The results show that the fuel economy is improved by 4.83%, and the acceleration performance of the full load 0~100 km/h is increased by 2.03%.
In this paper, the multi-objective particle swarm optimization (MOPSO) algorithm was used to optimized the transmission system parameters of vehicle. Firstly, according to the structure of the target vehicle, the whole vehicle model is built and validated by vehicle bench experiment. Secondly, the vehicle powertrain parameters are taken as design variables and the vehicle power and economy are taken as the optimization targets, a multi-objective optimization model of the vehicle is built. The transmission parameters are optimized by the multi-objective particle swarm algorithm. the Pareto optimal solution set is obtained by calculating the optimization parameters. Finally, the optimal transmission parameters are determined by the multiple attribute decision making method based on information entropy. Finally, the optimal transmission parameters were determined by the multiple attribute decision making method based on information entropy. The results show that the fuel economy is improved by 4.83%, and the acceleration performance of the full load 0~100 km/h is increased by 2.03%.
2018, 37(4): 635-640.
doi: 10.13433/j.cnki.1003-8728.2018.0422
Abstract:
The effects of the density, diameter of wire, diameter of spiral coil and temperature on the radial stiffness of ring metal rubber are analyzed via experiment. Taking the cantilever beams as the basic unit, the deformation of mental rubbers is analyzed. Combing with the temperature effect on the elastic modulus of wire and contact beams, the radial mechanical model for metal rubbers containing main parameters and temperature is established. Meanwhile, according to the experimental results, the parameters in the mechanical model are fitted and the concrete expression of the model is obtained. Comparing the model results with the experimental, it is found that the accuracy of the mechanical model is high and the model can comprehensively describe the radial stiffness of ring metal rubbers. It provides a theoretical reference for the practical application of metal rubbers.
The effects of the density, diameter of wire, diameter of spiral coil and temperature on the radial stiffness of ring metal rubber are analyzed via experiment. Taking the cantilever beams as the basic unit, the deformation of mental rubbers is analyzed. Combing with the temperature effect on the elastic modulus of wire and contact beams, the radial mechanical model for metal rubbers containing main parameters and temperature is established. Meanwhile, according to the experimental results, the parameters in the mechanical model are fitted and the concrete expression of the model is obtained. Comparing the model results with the experimental, it is found that the accuracy of the mechanical model is high and the model can comprehensively describe the radial stiffness of ring metal rubbers. It provides a theoretical reference for the practical application of metal rubbers.
2018, 37(4): 641-645.
doi: 10.13433/j.cnki.1003-8728.2018.0423
Abstract:
According to the structural characteristics of the inner and outer wing connection areas for a fighter wing, the finite element model of bolts connection structure in the wing connection areas is established. The bolts load is calculated by using the finite element software, and the sensitivity of the bolts layout parameter is analyzed. The influence of layout parameters on the load distribution is determined. By using the golden section method, the bolts layout parameters are optimized, which makes the bolts load of the most serious conditions decreased by 18.61%. Thus, the bearing capacity of the structure is well improved. The present study provides the basis for the design of the inner and outer wing connection areas for fighter wings.
According to the structural characteristics of the inner and outer wing connection areas for a fighter wing, the finite element model of bolts connection structure in the wing connection areas is established. The bolts load is calculated by using the finite element software, and the sensitivity of the bolts layout parameter is analyzed. The influence of layout parameters on the load distribution is determined. By using the golden section method, the bolts layout parameters are optimized, which makes the bolts load of the most serious conditions decreased by 18.61%. Thus, the bearing capacity of the structure is well improved. The present study provides the basis for the design of the inner and outer wing connection areas for fighter wings.
2018, 37(4): 646-651.
doi: 10.13433/j.cnki.1003-8728.2018.0424
Abstract:
The SpiderFab-type space manipulator is a typical space-based robot system. In order to quantitatively understand the influence on its floating base, which is caused by the motion of a manipulator, and to design its position and orientation control system, kinematics and dynamics equations are built. The coupling dynamics between a floating base and a manipulator is presented based on the conservation law of momentum. It is illustrated that the state change in the floating base is not only dependent on the current manipulator joint velocities but also joint paths. To deeply elaborate the coupled dynamics, three computer simulations of a space-based 3-degree-of-freedom (DOF) manipulator system are conducted. Three joint velocity inputs are given, and the post variation of the floating base is to be computed. The correctness of the method is demonstrated.
The SpiderFab-type space manipulator is a typical space-based robot system. In order to quantitatively understand the influence on its floating base, which is caused by the motion of a manipulator, and to design its position and orientation control system, kinematics and dynamics equations are built. The coupling dynamics between a floating base and a manipulator is presented based on the conservation law of momentum. It is illustrated that the state change in the floating base is not only dependent on the current manipulator joint velocities but also joint paths. To deeply elaborate the coupled dynamics, three computer simulations of a space-based 3-degree-of-freedom (DOF) manipulator system are conducted. Three joint velocity inputs are given, and the post variation of the floating base is to be computed. The correctness of the method is demonstrated.
2018, 37(4): 652-656.
doi: 10.13433/j.cnki.1003-8728.2018.0425
Abstract:
In the design of a certain type of airfoil,topology optimization and size optimization are used to reduce the weight of the spar. Based on the finite element method, the structure stiffness is improved by using the topology optimization with the minimal compliance of the spar as the objective function, the plate volume fraction as the constraint, the plate cell density as the design variable. By taking the volume of spar as objective function, the allowable stress of the spar as constraint and web thickness as design variable, size optimization are conducted for the main spar and the rear spar. Their weights was reduced by 26.5% and 27.7%, respectively. And their first natural frequencies are increased from 1.17 Hz and 4.34 Hz to 2.26 Hz and 4.59 Hz, respectively. The light weight design of the spar structures is achieved.
In the design of a certain type of airfoil,topology optimization and size optimization are used to reduce the weight of the spar. Based on the finite element method, the structure stiffness is improved by using the topology optimization with the minimal compliance of the spar as the objective function, the plate volume fraction as the constraint, the plate cell density as the design variable. By taking the volume of spar as objective function, the allowable stress of the spar as constraint and web thickness as design variable, size optimization are conducted for the main spar and the rear spar. Their weights was reduced by 26.5% and 27.7%, respectively. And their first natural frequencies are increased from 1.17 Hz and 4.34 Hz to 2.26 Hz and 4.59 Hz, respectively. The light weight design of the spar structures is achieved.
