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RSS2016 Vol. 35, No. 8
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2016, 35(8): 1149-1155.
doi: 10.13433/j.cnki.1003-8728.2016.0801
PDF 1107KB
Abstract:
The subspan oscillation for transmission lines is one type of the wind-induced vibrations, which can lead to insecurity of transmission lines. In this paper, the stability and bifurcation of the subspan oscillation for two bundled conductors are investigated. Firstly, the governing equations and mathematical models of the subspan oscillation system are given, and two Hopf bifurcation points are obtained. Then central manifold theory is used to reduce the dimension of the subspan oscillation system, and limit cycle oscillations near these two Hopf bifurcation points are also obtained. Lastly, the successor function method is used to analyze types of the Hopf bifurcation points. All these results agree with the numerical analysis solution well.
The subspan oscillation for transmission lines is one type of the wind-induced vibrations, which can lead to insecurity of transmission lines. In this paper, the stability and bifurcation of the subspan oscillation for two bundled conductors are investigated. Firstly, the governing equations and mathematical models of the subspan oscillation system are given, and two Hopf bifurcation points are obtained. Then central manifold theory is used to reduce the dimension of the subspan oscillation system, and limit cycle oscillations near these two Hopf bifurcation points are also obtained. Lastly, the successor function method is used to analyze types of the Hopf bifurcation points. All these results agree with the numerical analysis solution well.
2016, 35(8): 1156-1161.
doi: 10.13433/j.cnki.1003-8728.2016.0802
Abstract:
This paper is about the study on the inlet guide vane adjustment ability on part stage of vacuum centrifugal compressor, respectively to four kinds of circumstances, namely, entry without inlet guide vane, inlet guide vane 90°, 70°, 60°, and the flow performances are simulated in compressor stage. Through analyzing the simulation results, the laws of performance influence about inlet guide vane on vacuum centrifugal compressor are revealed. Finally, through analyzing the flow fields with the different blade heights based on planar structure inlet guide vane, we can see that the gas flow near blade roots at guide vane outlet does not match the impeller blade installation angle, and looking forward to guide vane application of curved face structure.
This paper is about the study on the inlet guide vane adjustment ability on part stage of vacuum centrifugal compressor, respectively to four kinds of circumstances, namely, entry without inlet guide vane, inlet guide vane 90°, 70°, 60°, and the flow performances are simulated in compressor stage. Through analyzing the simulation results, the laws of performance influence about inlet guide vane on vacuum centrifugal compressor are revealed. Finally, through analyzing the flow fields with the different blade heights based on planar structure inlet guide vane, we can see that the gas flow near blade roots at guide vane outlet does not match the impeller blade installation angle, and looking forward to guide vane application of curved face structure.
2016, 35(8): 1162-1168.
doi: 10.13433/j.cnki.1003-8728.2016.0803
Abstract:
To meet the requirements of minimally invasive surgery, the conceptual design of a novel surgery instrument with a flexible wrist is presented and the appropriate structural design and performance optimization studies are carried out. A flexible wrist with two degrees of freedom and a rigid driver platform are designed. According to the length variation of steel wire, we present the mapping model between the flexible wrist and the rigid driver platform by mathematical modeling and programming calculation. Finally, the overall structure and size parameters of the instrument are optimized. The experimental studies and performance tests based on the prototype verify the feasibility of the design procedure of the instrument.
To meet the requirements of minimally invasive surgery, the conceptual design of a novel surgery instrument with a flexible wrist is presented and the appropriate structural design and performance optimization studies are carried out. A flexible wrist with two degrees of freedom and a rigid driver platform are designed. According to the length variation of steel wire, we present the mapping model between the flexible wrist and the rigid driver platform by mathematical modeling and programming calculation. Finally, the overall structure and size parameters of the instrument are optimized. The experimental studies and performance tests based on the prototype verify the feasibility of the design procedure of the instrument.
2016, 35(8): 1169-1175.
doi: 10.13433/j.cnki.1003-8728.2016.0804
Abstract:
In order to ensure the stability of a quadruped robot walking with off-line planned trot gait, a new starting gait with many variable steps has been designed, and the mathematical and mechanical models of a quadruped robot have been constructed from the start to the stable walking. We use the MATLAB software to calculate out the data of the movement rule for every joint during the starting process, then put the data into the Adams dynamics simulation software for test-walking of the physical prototype model. Results of the experiment indicate that compared to the single-step start gait, this new start gait can minimize the posture-angle of the robot and effectively prevent the robot have a dramatic impact on the ground, besides the new start gait will keep the robot walking stably.
In order to ensure the stability of a quadruped robot walking with off-line planned trot gait, a new starting gait with many variable steps has been designed, and the mathematical and mechanical models of a quadruped robot have been constructed from the start to the stable walking. We use the MATLAB software to calculate out the data of the movement rule for every joint during the starting process, then put the data into the Adams dynamics simulation software for test-walking of the physical prototype model. Results of the experiment indicate that compared to the single-step start gait, this new start gait can minimize the posture-angle of the robot and effectively prevent the robot have a dramatic impact on the ground, besides the new start gait will keep the robot walking stably.
2016, 35(8): 1176-1182.
doi: 10.13433/j.cnki.1003-8728.2016.0805
Abstract:
On the basis of the predecessors' design scheme of annulus, the frame scheme is raised, which has smaller space usage and can promise real three-dimensional spatial movement. The comparison of the space usage of two schemes proves that the scheme of frame is more optimal. The frame scheme is taken as the object of study and the rotation frame 1 is taken as an example to establish the finite element model based on the structural feature. The static analysis is performed on the rotation frame 1 in the pose with the worst stiffness that is based on actual word condition. Modal analysis is taken with the first four inherent frequencies and vibration models. Multi-objective and multi-parameter optimization is taken according to the result of static analysis and modal analysis. Comparing with the analysis results of original modal via finite element method, we improve greatly the dynamic and static characters. The optimization results of pedestal and rotation frame 2 are provided with the same method.
On the basis of the predecessors' design scheme of annulus, the frame scheme is raised, which has smaller space usage and can promise real three-dimensional spatial movement. The comparison of the space usage of two schemes proves that the scheme of frame is more optimal. The frame scheme is taken as the object of study and the rotation frame 1 is taken as an example to establish the finite element model based on the structural feature. The static analysis is performed on the rotation frame 1 in the pose with the worst stiffness that is based on actual word condition. Modal analysis is taken with the first four inherent frequencies and vibration models. Multi-objective and multi-parameter optimization is taken according to the result of static analysis and modal analysis. Comparing with the analysis results of original modal via finite element method, we improve greatly the dynamic and static characters. The optimization results of pedestal and rotation frame 2 are provided with the same method.
2016, 35(8): 1183-1188.
doi: 10.13433/j.cnki.1003-8728.2016.0806
Abstract:
A new method called AR-GMM is proposed based on autoregressive model (AR) and Gaussian mixture model (GMM) for fault degree assessment. Bearing vibration signals are represented by the parameters and residual of the AR model. A GMM is then obtained by training data from bearing fault-free. The data to be tested are fed to the baseline GMM to measure the similarity between the tested bearing condition and normal ones. Consequently, a bearing fault degree assessment indicator called ARLLP (autoregressive log-likelihood probability) is formulated based on the similarity measure. Experiment results on bearing fatigue test demonstrate that the proposed method can detect bearing fault at early stage and can track the trend of deterioration of rolling bearings.
A new method called AR-GMM is proposed based on autoregressive model (AR) and Gaussian mixture model (GMM) for fault degree assessment. Bearing vibration signals are represented by the parameters and residual of the AR model. A GMM is then obtained by training data from bearing fault-free. The data to be tested are fed to the baseline GMM to measure the similarity between the tested bearing condition and normal ones. Consequently, a bearing fault degree assessment indicator called ARLLP (autoregressive log-likelihood probability) is formulated based on the similarity measure. Experiment results on bearing fatigue test demonstrate that the proposed method can detect bearing fault at early stage and can track the trend of deterioration of rolling bearings.
2016, 35(8): 1189-1194.
doi: 10.13433/j.cnki.1003-8728.2016.0807
Abstract:
Aiming at this problem that the previous researches of vibration characteristics for the main drive system of rolling mill about Alternating Current(AC) ignored considering the effects of electrical parameters, an electromechanical coupling mathematical model about vibration for the main drive system of rolling mill about AC is established, which considers the series capacitors in power network, the rotor resistance, the phase delay, the harmonic disturbances and other electrical factors of the AC asynchronous motor that combines the mechanism system. The effects about the series capacitors in power network, the rotor resistance, the phase delay, the harmonic disturbances and other electrical factors on the vibration characteristics in the main drive system of rolling mill are studied by numerical analysis. The research conclusion establishes further theoretical basis to analyze, diagnose and control vibration phenomenon in the main drive system of rolling mill about AC.
Aiming at this problem that the previous researches of vibration characteristics for the main drive system of rolling mill about Alternating Current(AC) ignored considering the effects of electrical parameters, an electromechanical coupling mathematical model about vibration for the main drive system of rolling mill about AC is established, which considers the series capacitors in power network, the rotor resistance, the phase delay, the harmonic disturbances and other electrical factors of the AC asynchronous motor that combines the mechanism system. The effects about the series capacitors in power network, the rotor resistance, the phase delay, the harmonic disturbances and other electrical factors on the vibration characteristics in the main drive system of rolling mill are studied by numerical analysis. The research conclusion establishes further theoretical basis to analyze, diagnose and control vibration phenomenon in the main drive system of rolling mill about AC.
2016, 35(8): 1195-1200.
doi: 10.13433/j.cnki.1003-8728.2016.0808
Abstract:
The pipes connecting compressor and heat exchange coils plays an important role in the noise and vibration performance of air conditioner. In this paper, the dynamic characteristics of the pipes are analyzed with both FEM (finite element method) and experimental method. The first twelve natural frequencies and mode shapes were obtained from dynamic analysis of FEM model. Then, the experimental modal analysis was performed on the real pipes with hammer excitation method. The differences between the FEM analysis and experimental results were compared, and solutions to suppress pipe vibration has been proposed. The study shows that pipe vibration dynamic characteristics, which can be efficiently verified by experimental modal analysis, provides reliable theoretical basis for controlling vibration and noise of air-conditioner pipes.
The pipes connecting compressor and heat exchange coils plays an important role in the noise and vibration performance of air conditioner. In this paper, the dynamic characteristics of the pipes are analyzed with both FEM (finite element method) and experimental method. The first twelve natural frequencies and mode shapes were obtained from dynamic analysis of FEM model. Then, the experimental modal analysis was performed on the real pipes with hammer excitation method. The differences between the FEM analysis and experimental results were compared, and solutions to suppress pipe vibration has been proposed. The study shows that pipe vibration dynamic characteristics, which can be efficiently verified by experimental modal analysis, provides reliable theoretical basis for controlling vibration and noise of air-conditioner pipes.
2016, 35(8): 1201-1206.
doi: 10.13433/j.cnki.1003-8728.2016.0809
Abstract:
In order to achieve the better stability balance of exoskeleton robot man-machine system in the walking process, a method is presented that the single leg support in swing phase adopting the energy analysis theory, establishing the connecting rod model and analyzing the center of gravity position, kinetic energy, potential energy and the changing rule of the joint torque of the exoskeleton man-machine system. Using the Adams software simulation to analyze the exoskeleton man-machine system under different load models, the results of the simulation suggest that the stability method is accurate. The stability study on the exoskeleton man-machine system can also provide the reference for the exoskeleton man-machine synchronization and other walking gaits stability balance control.
In order to achieve the better stability balance of exoskeleton robot man-machine system in the walking process, a method is presented that the single leg support in swing phase adopting the energy analysis theory, establishing the connecting rod model and analyzing the center of gravity position, kinetic energy, potential energy and the changing rule of the joint torque of the exoskeleton man-machine system. Using the Adams software simulation to analyze the exoskeleton man-machine system under different load models, the results of the simulation suggest that the stability method is accurate. The stability study on the exoskeleton man-machine system can also provide the reference for the exoskeleton man-machine synchronization and other walking gaits stability balance control.
2016, 35(8): 1207-1212.
doi: 10.13433/j.cnki.1003-8728.2016.0810
Abstract:
The generation function method is an important tool for structural reliability analysis and performance assessment of a multi-state system, but its computational efficiency and accuracy are poor. The non-uniform discretization method and the approximate merger technique are put forward. Firstly, the most dangerous point (minimum) of the safety margin function is obtained with the optimization method. Secondly, with the most dangerous point being at the center, each variable is non-uniformly discretized in accordance with the power function. Thirdly, variable generation functions are calculated by adopting the non-equidistant histogram method to test whether the discretization effect is optimal. Finally, the structural reliability is calculated. The generation function method not only improves its accuracy and efficiency but also avoids the combinatorial explosion under the condition that the number of the multi-state system's performance statuses does not change. The new method takes into consideration the error formation mechanism in calculating structural reliability and the MATLAB programming feasibility. It also provides an effective tool for the fast and efficient computation of the multi-variable nonlinear structural reliability with the finite-limit state function.
The generation function method is an important tool for structural reliability analysis and performance assessment of a multi-state system, but its computational efficiency and accuracy are poor. The non-uniform discretization method and the approximate merger technique are put forward. Firstly, the most dangerous point (minimum) of the safety margin function is obtained with the optimization method. Secondly, with the most dangerous point being at the center, each variable is non-uniformly discretized in accordance with the power function. Thirdly, variable generation functions are calculated by adopting the non-equidistant histogram method to test whether the discretization effect is optimal. Finally, the structural reliability is calculated. The generation function method not only improves its accuracy and efficiency but also avoids the combinatorial explosion under the condition that the number of the multi-state system's performance statuses does not change. The new method takes into consideration the error formation mechanism in calculating structural reliability and the MATLAB programming feasibility. It also provides an effective tool for the fast and efficient computation of the multi-variable nonlinear structural reliability with the finite-limit state function.
2016, 35(8): 1213-1218.
doi: 10.13433/j.cnki.1003-8728.2016.0811
Abstract:
Fast steering mirror (FSM) is also called Scanning Mirror. It is one of the key equipments in space communication, adaptive optics and other fields, which is used between the object and optical receiver to control the direction of light beams. Since the diversified demand of practical application, domestic fast steering mirrors are increasingly unable to meet the demand for high-end areas. According to the current domestic situation that only traditional one-sided scanning mirrors are studied, we design the mirror structure of double-sided scanning in the workplace which can realize working of both sides and the way to support the mirror so as to meet the specific requirement. Piezoelectric ceramics were used as the actuator. The support structure possessing fine flexibility in multiple directions and the base structure with amplification mechanism were analyzed and designed. Then a kind of device based on piezoelectric effect, consequently, making the double-sided mirror fast slope possible was given. Finally, the finite element method was applied to simulate and verify the design method and the entire structure presented in this paper.
Fast steering mirror (FSM) is also called Scanning Mirror. It is one of the key equipments in space communication, adaptive optics and other fields, which is used between the object and optical receiver to control the direction of light beams. Since the diversified demand of practical application, domestic fast steering mirrors are increasingly unable to meet the demand for high-end areas. According to the current domestic situation that only traditional one-sided scanning mirrors are studied, we design the mirror structure of double-sided scanning in the workplace which can realize working of both sides and the way to support the mirror so as to meet the specific requirement. Piezoelectric ceramics were used as the actuator. The support structure possessing fine flexibility in multiple directions and the base structure with amplification mechanism were analyzed and designed. Then a kind of device based on piezoelectric effect, consequently, making the double-sided mirror fast slope possible was given. Finally, the finite element method was applied to simulate and verify the design method and the entire structure presented in this paper.
2016, 35(8): 1219-1226.
doi: 10.13433/j.cnki.1003-8728.2016.0812
Abstract:
The mathematical model of the high-order elliptical gear tooth profile of the shaper cutter envelope is established based on the principles of meshing the shaper cutter and the high-order elliptical gear profile. The dynamic simulation program for the high-order elliptical gear tooth profile enveloped by shaper cutter is developed. According to the functional characteristics of the transmission ratio and pitch curve of the high-order elliptical gear profile, we deduce the equation for modifying the high-order elliptical gear profile. By modifying its pitch curve design parameters, the design defects such as overlap tooth, undercutting and overcutting are effectively reduced. The practicability and effectiveness of the design defect modification method are verified with some instances given in this paper.
The mathematical model of the high-order elliptical gear tooth profile of the shaper cutter envelope is established based on the principles of meshing the shaper cutter and the high-order elliptical gear profile. The dynamic simulation program for the high-order elliptical gear tooth profile enveloped by shaper cutter is developed. According to the functional characteristics of the transmission ratio and pitch curve of the high-order elliptical gear profile, we deduce the equation for modifying the high-order elliptical gear profile. By modifying its pitch curve design parameters, the design defects such as overlap tooth, undercutting and overcutting are effectively reduced. The practicability and effectiveness of the design defect modification method are verified with some instances given in this paper.
2016, 35(8): 1227-1232.
doi: 10.13433/j.cnki.1003-8728.2016.0813
Abstract:
In order to verify the blade in the design of used life whether is able to withstand the design rules fatigue loading, a megawatt wind turbine blade fatigue loading system was designed. The system is composed of a power transmission system, support system, control system and protection system. It realized signal acquisition and communication control with virtual instrument software, fuzzy PID control. With the counterweight block optimizing, the bending moment distribution error of a blade is reduced, and frequency searching and tracking, frequency capture and load spectrum loading test are completed. Experimental results show that the system can complete resonance frequency searching and tracking in step 0.01 Hz, maintenance of peak loading rate of change is within the error range of the test requirement (±5%), the blade root moment error is less than ±0.4%, and it provides a practical method for the detection and analysis of of wind turbine blade.
In order to verify the blade in the design of used life whether is able to withstand the design rules fatigue loading, a megawatt wind turbine blade fatigue loading system was designed. The system is composed of a power transmission system, support system, control system and protection system. It realized signal acquisition and communication control with virtual instrument software, fuzzy PID control. With the counterweight block optimizing, the bending moment distribution error of a blade is reduced, and frequency searching and tracking, frequency capture and load spectrum loading test are completed. Experimental results show that the system can complete resonance frequency searching and tracking in step 0.01 Hz, maintenance of peak loading rate of change is within the error range of the test requirement (±5%), the blade root moment error is less than ±0.4%, and it provides a practical method for the detection and analysis of of wind turbine blade.
2016, 35(8): 1233-1240.
doi: 10.13433/j.cnki.1003-8728.2016.0814
Abstract:
In order to improve the low frequency response of magnetofluid gyroscope, a method is proposed that apply electromagnetic pump technique to the research of magnetofluid gyroscope. The structure of its magnetic circuit is simulated three-dimensionally with ANSYS software and the simulation results show that the unevenness of magnetic flux density is much greater than 10%, which seriously affect the accuracy of the sensor. The different effects on the working gap magnetic field of different permanent magnets is simulated with the finite element method. And then the permanent magnet which has great influence on the homogeneity of magnetic field is removed in the structure design. Finally, the magnetic field of the working gap is properly designed and the inhomogeneity of the magnetic field is reduced. The simulation results show that the unevenness of magnetic flux density is less than 10%.
In order to improve the low frequency response of magnetofluid gyroscope, a method is proposed that apply electromagnetic pump technique to the research of magnetofluid gyroscope. The structure of its magnetic circuit is simulated three-dimensionally with ANSYS software and the simulation results show that the unevenness of magnetic flux density is much greater than 10%, which seriously affect the accuracy of the sensor. The different effects on the working gap magnetic field of different permanent magnets is simulated with the finite element method. And then the permanent magnet which has great influence on the homogeneity of magnetic field is removed in the structure design. Finally, the magnetic field of the working gap is properly designed and the inhomogeneity of the magnetic field is reduced. The simulation results show that the unevenness of magnetic flux density is less than 10%.
2016, 35(8): 1241-1246.
doi: 10.13433/j.cnki.1003-8728.2016.0815
Abstract:
The accurate and reasonable evaluation of an advanced bolt's reinforcement effect and its parameter design depend on correct understanding of reinforcement mechanisms. In order to explain the influence of parameters of soil and bolt on the reinforcement effect, the bolt-soil interactional model was built. The reinforcement mechanisms of advanced bolts were analyzed with the extrusion deformation of the tunnel core soil under the condition whether the advanced bolt and the tunnel core soil have common deformation or not. The reinforcement factor k was introduced to calculate the reinforcement effect of bolts and analyzed the influence of parameters for reinforcement effect in the condition that bolt and soil had common deformation. Finally, the reinforcement effect of the advanced bolt was analyzed through computer simulation. The simulation results show that the influence of soil and bolt's parameters on reinforcement effect can be analyzed with the reinforcement factor k. The conclusion that the length of an anchor has its limit is verified. Furthermore, the different reinforcement mechanisms of anchorage section and drawing section were explained. These results provide significant guidance for reinforcement effect evaluation and parameter design of an advanced bolt.
The accurate and reasonable evaluation of an advanced bolt's reinforcement effect and its parameter design depend on correct understanding of reinforcement mechanisms. In order to explain the influence of parameters of soil and bolt on the reinforcement effect, the bolt-soil interactional model was built. The reinforcement mechanisms of advanced bolts were analyzed with the extrusion deformation of the tunnel core soil under the condition whether the advanced bolt and the tunnel core soil have common deformation or not. The reinforcement factor k was introduced to calculate the reinforcement effect of bolts and analyzed the influence of parameters for reinforcement effect in the condition that bolt and soil had common deformation. Finally, the reinforcement effect of the advanced bolt was analyzed through computer simulation. The simulation results show that the influence of soil and bolt's parameters on reinforcement effect can be analyzed with the reinforcement factor k. The conclusion that the length of an anchor has its limit is verified. Furthermore, the different reinforcement mechanisms of anchorage section and drawing section were explained. These results provide significant guidance for reinforcement effect evaluation and parameter design of an advanced bolt.
2016, 35(8): 1247-1252.
doi: 10.13433/j.cnki.1003-8728.2016.0816
Abstract:
Considering the complexity of aerodynamic optimization for car during modeling design, we choose optimization of aerodynamic Characteristics for car. To verify the availability of Computational Fluid Dynamics(CFD) in two-dimension longitudinal symmetry plane model by comparing with surface cloud of three-dimension car model firstly. A parameterized longitudinal symmetry plane model is established. Then the ignificant parameters are selected as the design variables, the CFD calculation reflects the effect of the single structure parameters and coupling parameters on the car aerodynamic characteristics. High Dimensional Model Representation between the design variables and the objective functions is constructed based on the Thin Plate Spline Interpolation(TPS-HDMR). Moreover, multi-objective optimization method is applied in approximation model. Finally, a car reference database based on the results is established.
Considering the complexity of aerodynamic optimization for car during modeling design, we choose optimization of aerodynamic Characteristics for car. To verify the availability of Computational Fluid Dynamics(CFD) in two-dimension longitudinal symmetry plane model by comparing with surface cloud of three-dimension car model firstly. A parameterized longitudinal symmetry plane model is established. Then the ignificant parameters are selected as the design variables, the CFD calculation reflects the effect of the single structure parameters and coupling parameters on the car aerodynamic characteristics. High Dimensional Model Representation between the design variables and the objective functions is constructed based on the Thin Plate Spline Interpolation(TPS-HDMR). Moreover, multi-objective optimization method is applied in approximation model. Finally, a car reference database based on the results is established.
2016, 35(8): 1253-1258.
doi: 10.13433/j.cnki.1003-8728.2016.0817
Abstract:
In order to master the basic characteristics of handling and stability of the four-axle vehicle, based on the momentum theorem and angular momentum theorem, a 3DOF model of the four-axle vehicle is built, in which the influence of body roll on vehicle handling and stability is considered. Compared with 2DOF model, the 3DOF model can reflect the motion of four-axle vehicle more actually. By the response simulation of the proposed model under the front-wheel steering-angle step input, the influence of the change of vehicle parameters on vehicle handling and stability is analyzed, such as height and position of center of mass, roll stiffness, body mass. Then the vehicle design optimization can be finished based on the analysis results.
In order to master the basic characteristics of handling and stability of the four-axle vehicle, based on the momentum theorem and angular momentum theorem, a 3DOF model of the four-axle vehicle is built, in which the influence of body roll on vehicle handling and stability is considered. Compared with 2DOF model, the 3DOF model can reflect the motion of four-axle vehicle more actually. By the response simulation of the proposed model under the front-wheel steering-angle step input, the influence of the change of vehicle parameters on vehicle handling and stability is analyzed, such as height and position of center of mass, roll stiffness, body mass. Then the vehicle design optimization can be finished based on the analysis results.
2016, 35(8): 1259-1266.
doi: 10.13433/j.cnki.1003-8728.2016.0818
Abstract:
Interms of the Euler-Bernoulli beam theory, the parametric model for vertical vibration of equivalent car-body structure is built. For more accurate calculation results, the car-body is divided into some parts for getting the section information and obtaining a convergence coefficient to get the corrected formula by the degree of inequality about the car-body parts. All of these measures give an exact first order vertical bending frequency of the simple car-bodies. By applying the key parameters to calculate the first order vertical bending frequency of a subway car-body and a high-speed train car-body, the results show that the error between the analyzed value and the finite element result is 2.05% and 4.59%, and the error about the modal experiment of the high-speed train is 1.18 Hz. All the errors between the analyzed value and the finite element result are all in the range of 5%, which show that the analyzed method is effective.
Interms of the Euler-Bernoulli beam theory, the parametric model for vertical vibration of equivalent car-body structure is built. For more accurate calculation results, the car-body is divided into some parts for getting the section information and obtaining a convergence coefficient to get the corrected formula by the degree of inequality about the car-body parts. All of these measures give an exact first order vertical bending frequency of the simple car-bodies. By applying the key parameters to calculate the first order vertical bending frequency of a subway car-body and a high-speed train car-body, the results show that the error between the analyzed value and the finite element result is 2.05% and 4.59%, and the error about the modal experiment of the high-speed train is 1.18 Hz. All the errors between the analyzed value and the finite element result are all in the range of 5%, which show that the analyzed method is effective.
2016, 35(8): 1267-1272.
doi: 10.13433/j.cnki.1003-8728.2016.0819
Abstract:
In order to improve the accuracy of assessing the technical state of tank power drive device, a synthetic mathematical model was studied and built. At first, the synthetic mathematical model was built by analytic hierarchy process. After analyzing the basic principle of variable weight synthetic method, the fuzzy theory was used to make a fuzzy process for assessing parameters and get every assessing parameter's fuzzy membership grade. The technical state of two tank power drive devices with same motor hours was assessed by using fuzzy variable weight method and the quantitative assessing results were gotten. At last, a quantitative standard for assessing the technical state of tank power drive device was established. The assessing results show that the variable weight synthetic method is reasonable and scientific for assessing the technical state of tank power drive device.
In order to improve the accuracy of assessing the technical state of tank power drive device, a synthetic mathematical model was studied and built. At first, the synthetic mathematical model was built by analytic hierarchy process. After analyzing the basic principle of variable weight synthetic method, the fuzzy theory was used to make a fuzzy process for assessing parameters and get every assessing parameter's fuzzy membership grade. The technical state of two tank power drive devices with same motor hours was assessed by using fuzzy variable weight method and the quantitative assessing results were gotten. At last, a quantitative standard for assessing the technical state of tank power drive device was established. The assessing results show that the variable weight synthetic method is reasonable and scientific for assessing the technical state of tank power drive device.
2016, 35(8): 1273-1279.
doi: 10.13433/j.cnki.1003-8728.2016.0820
Abstract:
An abradable sealing coating is widely used in aeroengine, which the thermal shock-resistance is one of the important elements on its reliability. The elastic modulus of the coating with three point bending method is measured. The stress distribution of sample during the thermal shock process was obtained via ABAQUS, the effect of the bonding coating thickness on the stress change was analyzed. The results show that the tensile stress of most points between the coating and the substrate are decreased with the increasing of bonding coating thickness, and the compressive stress on some points are increased. Comparing with the thermal shock test, the thermal shock-resistance of abradable sealing coating meet the standard. The thermal shock-resistance can be improved by increasing bonding coating thickness.
An abradable sealing coating is widely used in aeroengine, which the thermal shock-resistance is one of the important elements on its reliability. The elastic modulus of the coating with three point bending method is measured. The stress distribution of sample during the thermal shock process was obtained via ABAQUS, the effect of the bonding coating thickness on the stress change was analyzed. The results show that the tensile stress of most points between the coating and the substrate are decreased with the increasing of bonding coating thickness, and the compressive stress on some points are increased. Comparing with the thermal shock test, the thermal shock-resistance of abradable sealing coating meet the standard. The thermal shock-resistance can be improved by increasing bonding coating thickness.
2016, 35(8): 1280-1285.
doi: 10.13433/j.cnki.1003-8728.2016.0821
Abstract:
Failure test and post-buckling analysis techniques were studied subject to the stability and load carrying capacity of the composite stiffened panel under shear load. Considering the progressive damage, we establish the shear failure analysis model based on the three dimensional Hashin failure criteria and quadratic nominal strain criteria. Moreover, a user defined subroutine UMAT of material failure criteria and degradation rule was programmed based on ABAQUS, and the load carrying capacity of the structure was analyzed. The comparison indicates that the load carrying capacity, failure modes and shear strain evolvement of numerical analysis agree well with test results, and the errors of predicted buckling load and load carrying capacity are 5.4% and 3.5% respectively, which validates the rationality and efficiency of the FE model of the composite stiffened panel in this paper.
Failure test and post-buckling analysis techniques were studied subject to the stability and load carrying capacity of the composite stiffened panel under shear load. Considering the progressive damage, we establish the shear failure analysis model based on the three dimensional Hashin failure criteria and quadratic nominal strain criteria. Moreover, a user defined subroutine UMAT of material failure criteria and degradation rule was programmed based on ABAQUS, and the load carrying capacity of the structure was analyzed. The comparison indicates that the load carrying capacity, failure modes and shear strain evolvement of numerical analysis agree well with test results, and the errors of predicted buckling load and load carrying capacity are 5.4% and 3.5% respectively, which validates the rationality and efficiency of the FE model of the composite stiffened panel in this paper.
2016, 35(8): 1286-1290.
doi: 10.13433/j.cnki.1003-8728.2016.0822
Abstract:
Considering the existing research gap, we propose a modified Relevance Vector Machine (RVM) to make an online prediction of RUL. Firstly, the training dataset with lithium-ion batteries' capacity data and phase space reconstruction technique is constructed. Then, the traditional RVM by adopting a multi-kernel function is modified in order to improve the accuracy and generalizability of the original RVM model. In addition, the particle swarm optimization algorithm is employed to adaptively search the optimal parameter combination of the multi-kernel RVM. The experimental results show that the present model is capable to predict the online RUL of lithium-ion battery more accurate than that of single kernel RVM.
Considering the existing research gap, we propose a modified Relevance Vector Machine (RVM) to make an online prediction of RUL. Firstly, the training dataset with lithium-ion batteries' capacity data and phase space reconstruction technique is constructed. Then, the traditional RVM by adopting a multi-kernel function is modified in order to improve the accuracy and generalizability of the original RVM model. In addition, the particle swarm optimization algorithm is employed to adaptively search the optimal parameter combination of the multi-kernel RVM. The experimental results show that the present model is capable to predict the online RUL of lithium-ion battery more accurate than that of single kernel RVM.
2016, 35(8): 1291-1296.
doi: 10.13433/j.cnki.1003-8728.2016.0823
Abstract:
The risk assessment method for aero engine component failure has been developed via Monte Carlo method with the history data. The methods for classifying failure hazard level, determining hazard ratio and calculating risk factor have been given. The occurrence for aero engine component failure has been predicted, and the failure risk for aero engine during operation phase has been evaluated so as to ensure the reliability and security. The risk assessment for an aero-engine component failure has been performed on the basis of the failure events hazard level and the corresponding risk guidelines. During risk assessment, three reasonable corrective actions have been developed to analyze the impact of different maintenance methods and inspectional intervals on the failure risk factor, and to choose a reasonable risk reduction program.
The risk assessment method for aero engine component failure has been developed via Monte Carlo method with the history data. The methods for classifying failure hazard level, determining hazard ratio and calculating risk factor have been given. The occurrence for aero engine component failure has been predicted, and the failure risk for aero engine during operation phase has been evaluated so as to ensure the reliability and security. The risk assessment for an aero-engine component failure has been performed on the basis of the failure events hazard level and the corresponding risk guidelines. During risk assessment, three reasonable corrective actions have been developed to analyze the impact of different maintenance methods and inspectional intervals on the failure risk factor, and to choose a reasonable risk reduction program.
2016, 35(8): 1297-1301.
doi: 10.13433/j.cnki.1003-8728.2016.0824
Abstract:
A novel construction method of three-dimensional process model based on the curve offset is proposed, which tackles the problem of converting a blank to a product part in a three-dimensional CAPP system. Firstly, the expression of the curve and offset curve, the offset rules of line and arc and the intersection rules are presented. Secondly, under a given the allowance and tool radius, the offset curve is obtained by offsetting the outer loop of machining features. Finally, the 3D process model is generated by extruding the offset curve and executing the Boolean operation on the precursor process model. The experimental results demonstrate the effectiveness of the proposed method.
A novel construction method of three-dimensional process model based on the curve offset is proposed, which tackles the problem of converting a blank to a product part in a three-dimensional CAPP system. Firstly, the expression of the curve and offset curve, the offset rules of line and arc and the intersection rules are presented. Secondly, under a given the allowance and tool radius, the offset curve is obtained by offsetting the outer loop of machining features. Finally, the 3D process model is generated by extruding the offset curve and executing the Boolean operation on the precursor process model. The experimental results demonstrate the effectiveness of the proposed method.
2016, 35(8): 1302-1307.
doi: 10.13433/j.cnki.1003-8728.2016.0825
Abstract:
This paper studies the separation of the engine vibration signal based on independent component analysis (independent component analysis, abbreviated as ICA) method, its purpose is to separate the mixed signals of rotor vibration. First of all, two methods of ICA that are about Infomax and FastICA methods are studied on their separation effect of aliasing signal; then, the vibration signal of LABVIEW signal acquisition system collects the rotor, the source signals from the mixed signals are separated by the method; finally, a test on rotor vibration signal of rotor misalignment and rubbing two working states of separation is made to verify the applicability and effectiveness of the method.
This paper studies the separation of the engine vibration signal based on independent component analysis (independent component analysis, abbreviated as ICA) method, its purpose is to separate the mixed signals of rotor vibration. First of all, two methods of ICA that are about Infomax and FastICA methods are studied on their separation effect of aliasing signal; then, the vibration signal of LABVIEW signal acquisition system collects the rotor, the source signals from the mixed signals are separated by the method; finally, a test on rotor vibration signal of rotor misalignment and rubbing two working states of separation is made to verify the applicability and effectiveness of the method.
2016, 35(8): 1308-1312.
doi: 10.13433/j.cnki.1003-8728.2016.0826
Abstract:
To overcome the shortcomings of the traditional grid method, we use a honeycomb grid to model its environment and the distribution-uniform adaptive ant colony algorithm for mobile robot path planning in a complex static environment. The algorithm uses the safety and effectiveness of honeycomb grid through the cohesion and the information weights to dynamically adjust the path selection probability and pheromone updating, makes the algorithm quickly converge, avoids prematurity and stagnation and achieves a good balance. The simulation results demonstrate that the algorithm is significantly superior to the traditional ant colony algorithm in terms of three important parameters. Thus, in the environment of any known complex static obstacles, the algorithm can quickly, accurately and safely plan the optimal path of a mobile robot and produce satisfactory results.
To overcome the shortcomings of the traditional grid method, we use a honeycomb grid to model its environment and the distribution-uniform adaptive ant colony algorithm for mobile robot path planning in a complex static environment. The algorithm uses the safety and effectiveness of honeycomb grid through the cohesion and the information weights to dynamically adjust the path selection probability and pheromone updating, makes the algorithm quickly converge, avoids prematurity and stagnation and achieves a good balance. The simulation results demonstrate that the algorithm is significantly superior to the traditional ant colony algorithm in terms of three important parameters. Thus, in the environment of any known complex static obstacles, the algorithm can quickly, accurately and safely plan the optimal path of a mobile robot and produce satisfactory results.
