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RSS2016 Vol. 35, No. 11
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2016, 35(11): 1641-1644.
doi: 10.13433/j.cnki.1003-8728.2016.1101
PDF 1587KB
Abstract:
In the vibration environment, bolted joints are tending to be loosed in service. Based on a bolted frame structure random vibration testing, a vibration-based bolt looseness detecting method is developed by analyzing response signal from bolt joints of various torque states in this paper. Through the discussion about differences of the power spectral density of signals, the nonlinearity of response caused by bolt looseness is analyzed. Using the high-frequency intrinsic mode functions which contain the frequency modulation ingredient based on ensemble empirical mode decomposition (EEMD), an effective energy-based damage index is established to detect the presence of the damage. The experimental result demonstrates that the proposed energy-based damage index based on high-frequency intrinsic mode functions can be used to accurately detect the nonlinear damage caused by bolt looseness under various torque states.
In the vibration environment, bolted joints are tending to be loosed in service. Based on a bolted frame structure random vibration testing, a vibration-based bolt looseness detecting method is developed by analyzing response signal from bolt joints of various torque states in this paper. Through the discussion about differences of the power spectral density of signals, the nonlinearity of response caused by bolt looseness is analyzed. Using the high-frequency intrinsic mode functions which contain the frequency modulation ingredient based on ensemble empirical mode decomposition (EEMD), an effective energy-based damage index is established to detect the presence of the damage. The experimental result demonstrates that the proposed energy-based damage index based on high-frequency intrinsic mode functions can be used to accurately detect the nonlinear damage caused by bolt looseness under various torque states.
2016, 35(11): 1645-1651.
doi: 10.13433/j.cnki.1003-8728.2016.1102
Abstract:
Based on the topological graph in theory of mechanism, the topological characteristics of common independent suspension guiding mechanism were analyzed. According to the design requirements and the over-constraint features of structure, with the freedom of movement for the target, the type synthesis of a class of three loops kinematic chains for independent suspension guiding mechanism was constructed to obtain the required mobility. Then the structural of independent suspension mechanism was carried out. Based on the above results, by using the screw theory, the degree of freedom and over-constraint features of a new guiding mechanism were analyzed. On the basis of the design requirements and space constraints of guiding mechanism, the simulation model of the new type guiding mechanism was established with ADAMS, and kinematics characteristics of the new type guiding mechanism were analyzed. The analysis results show that the new type guiding mechanism meets the requirements of suspension mechanism, it indirectly verifies the feasibility and effectiveness of this design method.
Based on the topological graph in theory of mechanism, the topological characteristics of common independent suspension guiding mechanism were analyzed. According to the design requirements and the over-constraint features of structure, with the freedom of movement for the target, the type synthesis of a class of three loops kinematic chains for independent suspension guiding mechanism was constructed to obtain the required mobility. Then the structural of independent suspension mechanism was carried out. Based on the above results, by using the screw theory, the degree of freedom and over-constraint features of a new guiding mechanism were analyzed. On the basis of the design requirements and space constraints of guiding mechanism, the simulation model of the new type guiding mechanism was established with ADAMS, and kinematics characteristics of the new type guiding mechanism were analyzed. The analysis results show that the new type guiding mechanism meets the requirements of suspension mechanism, it indirectly verifies the feasibility and effectiveness of this design method.
2016, 35(11): 1652-1656.
doi: 10.13433/j.cnki.1003-8728.2016.1103
Abstract:
In order to realize visualization of the locomotion process of industrial robot, the kinematic simulation for industrial robot is studied based on OpenGL and VC++ program language. The trajectory generation is an important part in the kinematic simulation, therefore, the procedure of trajectory generation and its specific implementation approach were studied in details in this paper. Besides, the trajectory planning algorithm was particularly studied. The Bezier curve uniform interpolation method was adopted to eliminate the impact the junction of continues path on motion smoothness. All the algorithms were numerically simulated and experiment was carried out, which verified the feasibility of the visual kinematic simulation system.
In order to realize visualization of the locomotion process of industrial robot, the kinematic simulation for industrial robot is studied based on OpenGL and VC++ program language. The trajectory generation is an important part in the kinematic simulation, therefore, the procedure of trajectory generation and its specific implementation approach were studied in details in this paper. Besides, the trajectory planning algorithm was particularly studied. The Bezier curve uniform interpolation method was adopted to eliminate the impact the junction of continues path on motion smoothness. All the algorithms were numerically simulated and experiment was carried out, which verified the feasibility of the visual kinematic simulation system.
2016, 35(11): 1657-1664.
doi: 10.13433/j.cnki.1003-8728.2016.1104
Abstract:
The progress of science and technology makes the environment vibration into electrical energy as possible, now it has become the hot topics in the study of energy harvester. The system dynamics equation of bistable electromagnetic energy harvester with an auxiliary linear oscillator is established, from the perspective of numerical simulations to study dynamic behavior of bistable energy harvester with an auxiliary linear oscillator under white noise excitation; the effects of noise intensity, mass ratio and frequency ratio of the system on the electricity generating performance are analyzed. The computed results show that with the noise intensity, mass ratio and frequency ratio increase, the motion amplitude of bistable power oscillator is increased, and will generate substantial chaotic motion, while the output voltage of the system is also in constant increase. The study provides a theoretical basis for bistable electromagnetic energy harvester system research.
The progress of science and technology makes the environment vibration into electrical energy as possible, now it has become the hot topics in the study of energy harvester. The system dynamics equation of bistable electromagnetic energy harvester with an auxiliary linear oscillator is established, from the perspective of numerical simulations to study dynamic behavior of bistable energy harvester with an auxiliary linear oscillator under white noise excitation; the effects of noise intensity, mass ratio and frequency ratio of the system on the electricity generating performance are analyzed. The computed results show that with the noise intensity, mass ratio and frequency ratio increase, the motion amplitude of bistable power oscillator is increased, and will generate substantial chaotic motion, while the output voltage of the system is also in constant increase. The study provides a theoretical basis for bistable electromagnetic energy harvester system research.
2016, 35(11): 1665-1672.
doi: 10.13433/j.cnki.1003-8728.2016.1105
Abstract:
With the increasing of lower limb movement disorder, a type of gait rehabilitation training robot has been designed. The whole mechanical structure and control system are designed to build the robot according to the requirements of gait rehabilitation training. Using the human gait analyzing system INSENCO, the lots of experiments have been measured and recorded the human gait data. And the result indicates that the robot has achieved the goal of free movement and weight-supporting. And the weight-supporting mechanism are flexible both the height and the tension so as to realize the goal of rehabilitation training.
With the increasing of lower limb movement disorder, a type of gait rehabilitation training robot has been designed. The whole mechanical structure and control system are designed to build the robot according to the requirements of gait rehabilitation training. Using the human gait analyzing system INSENCO, the lots of experiments have been measured and recorded the human gait data. And the result indicates that the robot has achieved the goal of free movement and weight-supporting. And the weight-supporting mechanism are flexible both the height and the tension so as to realize the goal of rehabilitation training.
2016, 35(11): 1673-1678.
doi: 10.13433/j.cnki.1003-8728.2016.1106
Abstract:
Vibroseis has become the current main equipment for oil and gas green exploration. The vibrator baseplate, one of the core parts of the vibroseis, is the key to exploration, whose structure and performance directly affect the quality of the output signal. In order to study the performances of KZ-28 vibroseis vibrator baseplate under dynamic loads, the vibrator-ground model was established according to the theory of finite element analysis. These five evaluation indicators, safety of the vibrator structural, interaction between the baseplate and the ground, deformation of the baseplate, decoupling of the baseplate, contact force between the baseplate and the ground, and baseplate energy transfer rate were analyzed by using LS-DYNA software to study the performance of the baseplate. The analysis result shows the baseplate under dynamic loads exists bending, the contact force distribution is very uneven, and the baseplate and the ground happens "decoupling".
Vibroseis has become the current main equipment for oil and gas green exploration. The vibrator baseplate, one of the core parts of the vibroseis, is the key to exploration, whose structure and performance directly affect the quality of the output signal. In order to study the performances of KZ-28 vibroseis vibrator baseplate under dynamic loads, the vibrator-ground model was established according to the theory of finite element analysis. These five evaluation indicators, safety of the vibrator structural, interaction between the baseplate and the ground, deformation of the baseplate, decoupling of the baseplate, contact force between the baseplate and the ground, and baseplate energy transfer rate were analyzed by using LS-DYNA software to study the performance of the baseplate. The analysis result shows the baseplate under dynamic loads exists bending, the contact force distribution is very uneven, and the baseplate and the ground happens "decoupling".
2016, 35(11): 1679-1685.
doi: 10.13433/j.cnki.1003-8728.2016.1107
Abstract:
In order to obtain structures of hybrid robot, a very simple yet very effective structural design of decoupled hybrid mechanism and its principle for type synthesis are proposed based on GF set. The basic concept and algorithms for GF set are firstly introduced. Secondly, the topological arrangements of hybrid mechanisms can be developed by the elements of GF set combination and rotation axis transfer theorem. Following the selection criterion of the input pair and type synthesis principle of decoupled branches are given, therefore it ensures that the various branches' inputs are decoupled. According to the type synthesis theory, specific process for structural synthesis of 2T2R four degrees of freedom decoupled hybrid mechanism is finished. Finally, a method is proposed to analyze kinematics characteristic of hybrid mechanisms synthesized above. The expression of the Jacobian matrix was deduced which validates the decoupling feature of the mechanism, in addition, it demonstrates the effectiveness of the novel method of structural synthesis for hybrid mechanisms.
In order to obtain structures of hybrid robot, a very simple yet very effective structural design of decoupled hybrid mechanism and its principle for type synthesis are proposed based on GF set. The basic concept and algorithms for GF set are firstly introduced. Secondly, the topological arrangements of hybrid mechanisms can be developed by the elements of GF set combination and rotation axis transfer theorem. Following the selection criterion of the input pair and type synthesis principle of decoupled branches are given, therefore it ensures that the various branches' inputs are decoupled. According to the type synthesis theory, specific process for structural synthesis of 2T2R four degrees of freedom decoupled hybrid mechanism is finished. Finally, a method is proposed to analyze kinematics characteristic of hybrid mechanisms synthesized above. The expression of the Jacobian matrix was deduced which validates the decoupling feature of the mechanism, in addition, it demonstrates the effectiveness of the novel method of structural synthesis for hybrid mechanisms.
2016, 35(11): 1686-1690.
doi: 10.13433/j.cnki.1003-8728.2016.1108
Abstract:
The Extension performance plays an important role in take-off of Carrier-based aircraft. In this paper, the extension dynamic performance of an oleo-pneumatic shock absorber with a dual-chamber is modeled, and studied with the home made simulation code. The test for catapult launch-extension of the nose landing gear is designed, and the data of extension dynamic performance was obtained successfully in the test, and the phenomenon of the test is analyzed. The simulation results agree well with that of the test. The effect of variations of a set of structural and filling parameters from the original design data on the extension performance of the landing gear is studied. The results show thatthe extension performance can be improved with the optimal parameters including the oil gallery diameter, the initial pressure of chamber, the initial pressure of tire, the low-pressure volume ratio of the dual-chamber and the dimension of the metering pin.
The Extension performance plays an important role in take-off of Carrier-based aircraft. In this paper, the extension dynamic performance of an oleo-pneumatic shock absorber with a dual-chamber is modeled, and studied with the home made simulation code. The test for catapult launch-extension of the nose landing gear is designed, and the data of extension dynamic performance was obtained successfully in the test, and the phenomenon of the test is analyzed. The simulation results agree well with that of the test. The effect of variations of a set of structural and filling parameters from the original design data on the extension performance of the landing gear is studied. The results show thatthe extension performance can be improved with the optimal parameters including the oil gallery diameter, the initial pressure of chamber, the initial pressure of tire, the low-pressure volume ratio of the dual-chamber and the dimension of the metering pin.
2016, 35(11): 1691-1697.
doi: 10.13433/j.cnki.1003-8728.2016.1109
Abstract:
In order to solve the pressure curve controlling problem in deep buoyancy escape, this paper designs the escape simulation and experimental device of a gas pressurizing control system based on the fuzzy adaptive Proportion Integration Differentiation (PID) control algorithm. It analyzes the fast pressurizing control system in theory, and establishes its digital model with the AMESim + Simulink co-simulation platform. It then describes how the following factors-including control strategies, delay and spool characteristics of the pneumatic regulation valve, pressure measurement errors-influence the control effect of the pressurizing control system. It improves its dynamic responding speed, control precision and robustness of the gas pressurizing control system with the fuzzy adaptive PID control strategy, thus maintaining the system stability. The simulation results and the experimental results on the escape simulation device show that the fuzzy adaptive PID control strategy is feasible and valid.
In order to solve the pressure curve controlling problem in deep buoyancy escape, this paper designs the escape simulation and experimental device of a gas pressurizing control system based on the fuzzy adaptive Proportion Integration Differentiation (PID) control algorithm. It analyzes the fast pressurizing control system in theory, and establishes its digital model with the AMESim + Simulink co-simulation platform. It then describes how the following factors-including control strategies, delay and spool characteristics of the pneumatic regulation valve, pressure measurement errors-influence the control effect of the pressurizing control system. It improves its dynamic responding speed, control precision and robustness of the gas pressurizing control system with the fuzzy adaptive PID control strategy, thus maintaining the system stability. The simulation results and the experimental results on the escape simulation device show that the fuzzy adaptive PID control strategy is feasible and valid.
2016, 35(11): 1698-1702.
doi: 10.13433/j.cnki.1003-8728.2016.1110
Abstract:
The magnetic-geared motor is a permanent magnetic drive element with novel electromagnetic structure, which has the advantages of high torque density, high torque at low speed, etc. The work principle and the cogging torque expression of the magnetic-geared motor are analyzed first in this paper. Then several factors which influence the cogging torque of the motor are obtained. A two-dimensional model of the motor is established by the finite element method and each factor is simulated separately. At last, the change relationship between cogging torque and the size of components or the materials of permanent magnets is displayed.
The magnetic-geared motor is a permanent magnetic drive element with novel electromagnetic structure, which has the advantages of high torque density, high torque at low speed, etc. The work principle and the cogging torque expression of the magnetic-geared motor are analyzed first in this paper. Then several factors which influence the cogging torque of the motor are obtained. A two-dimensional model of the motor is established by the finite element method and each factor is simulated separately. At last, the change relationship between cogging torque and the size of components or the materials of permanent magnets is displayed.
2016, 35(11): 1703-1708.
doi: 10.13433/j.cnki.1003-8728.2016.1111
Abstract:
In drilling hybrid structure of composite materials and titanium alloys, thrust force that results in interlayer gap was calculated, the predictive model of critical pressure foot force was established for elimination of interlayer damage. Experiments were carried out with varying feed rate and stiffness of workpiece. The formation of interlayer defects was studied, as well as the relationship between interlayer defects and experimental parameters. Interlayer defects include interlayer chips and scratch of composite surface, which are formed during extending and accumulating process of chips along interlayer gap. The defects increase with the increasing of feed rate and the decreasing of stiffness. Correlation analysis shows a significant positive relationship between interlayer defects and interlayer gap. Pressure foot force will reduce the interlayer gap and defects. When the pressure foot force equals the critical value there is almost no interlayer defects.
In drilling hybrid structure of composite materials and titanium alloys, thrust force that results in interlayer gap was calculated, the predictive model of critical pressure foot force was established for elimination of interlayer damage. Experiments were carried out with varying feed rate and stiffness of workpiece. The formation of interlayer defects was studied, as well as the relationship between interlayer defects and experimental parameters. Interlayer defects include interlayer chips and scratch of composite surface, which are formed during extending and accumulating process of chips along interlayer gap. The defects increase with the increasing of feed rate and the decreasing of stiffness. Correlation analysis shows a significant positive relationship between interlayer defects and interlayer gap. Pressure foot force will reduce the interlayer gap and defects. When the pressure foot force equals the critical value there is almost no interlayer defects.
2016, 35(11): 1709-1714.
doi: 10.13433/j.cnki.1003-8728.2016.1112
Abstract:
To solve the problem of the material removal rate in the large surface supple compliant process, the material removal volume is modeled for the contact area between the supple polishing tool and the large surface. The coefficient of friction is the main factor to inluence the material removal is deduced. Based on the large surface supple polishing tool system and CNC milling machine, the experimental platform has carried out for friction coefficient test and motor current monitoring. The experiment results show that the coefficient of friction increases with to the increasing of dwell time, the existence of the corresponding real-time relationship between the motor current and the polishing force. The combination of the theoretical results with the experiment verifies that the influence of the friction coefficient on the amount of material removal.
To solve the problem of the material removal rate in the large surface supple compliant process, the material removal volume is modeled for the contact area between the supple polishing tool and the large surface. The coefficient of friction is the main factor to inluence the material removal is deduced. Based on the large surface supple polishing tool system and CNC milling machine, the experimental platform has carried out for friction coefficient test and motor current monitoring. The experiment results show that the coefficient of friction increases with to the increasing of dwell time, the existence of the corresponding real-time relationship between the motor current and the polishing force. The combination of the theoretical results with the experiment verifies that the influence of the friction coefficient on the amount of material removal.
2016, 35(11): 1715-1720.
doi: 10.13433/j.cnki.1003-8728.2016.1113
Abstract:
Aiming at reducing computational cost and time for expensive multi-objective optimization problem of complex mechanical systems, a multi-objective optimization method based on approximate model with a parallel update point adaptively adding strategy is put forward. In this approach, based on a Kriging model, the point adding strategy is formulated as a dynamic multi-objective optimization problem which considers both Pareto optimal solutions and model uncertainty. By applying an improved NSGA-II and a maximum distance criterion, multiple update points can be identified for further parallel evaluation. The proposed approach is tested on six numerical functions and one engineering example. The results show that, this method not only is able to obtain Pareto optimal solutions of good convergence and diversity, but also possess the advantage in the optimization efficiency.
Aiming at reducing computational cost and time for expensive multi-objective optimization problem of complex mechanical systems, a multi-objective optimization method based on approximate model with a parallel update point adaptively adding strategy is put forward. In this approach, based on a Kriging model, the point adding strategy is formulated as a dynamic multi-objective optimization problem which considers both Pareto optimal solutions and model uncertainty. By applying an improved NSGA-II and a maximum distance criterion, multiple update points can be identified for further parallel evaluation. The proposed approach is tested on six numerical functions and one engineering example. The results show that, this method not only is able to obtain Pareto optimal solutions of good convergence and diversity, but also possess the advantage in the optimization efficiency.
2016, 35(11): 1721-1726.
doi: 10.13433/j.cnki.1003-8728.2016.1114
Abstract:
A third-order non-uniform rational B-spline (NURBS) interpolation algorithm based on Obrechkoff parameterization was proposed to satisfy the requirements of the high-precision machining of complex curve surface in the engineering practice. For furthermore ensuring the high-precision of calculation and real time control of interpolation, the parametric interpolation algorithm based on Obrechkoff was predigested by using rearward difference in place of differential to reduce the computational complexity of the algorithm. Considering the fairness effect of different parameterization, then compared the proposed algorithm with the accumulative chord length parameterization and the Adams parameterization in MATLAB, the computer simulation experiments indicate that the interpolation curve which simulated by the algorithm is more fairness because its average curvature is lowest.
A third-order non-uniform rational B-spline (NURBS) interpolation algorithm based on Obrechkoff parameterization was proposed to satisfy the requirements of the high-precision machining of complex curve surface in the engineering practice. For furthermore ensuring the high-precision of calculation and real time control of interpolation, the parametric interpolation algorithm based on Obrechkoff was predigested by using rearward difference in place of differential to reduce the computational complexity of the algorithm. Considering the fairness effect of different parameterization, then compared the proposed algorithm with the accumulative chord length parameterization and the Adams parameterization in MATLAB, the computer simulation experiments indicate that the interpolation curve which simulated by the algorithm is more fairness because its average curvature is lowest.
2016, 35(11): 1727-1732.
doi: 10.13433/j.cnki.1003-8728.2016.1115
Abstract:
In order to solve the problems that white noise parameters need artificial selection in EEMD (ensemble empirical mode decomposition) and considering the situation that plenty of samples of typical faults are difficult to obtain in reality, an bearing fault diagnosis method based on adaptive EEMD (AEEMD) and SVM (support vector machine) is proposed. First of all, AEEMD is used to decompose the vibration signal into several IMFs (intrinsic mode functions) of different characteristic time scales in signal processing. To different bearing faults, the energy of signals in different frequency bands can change, so energy of IMFs can be used to realize fault feature extraction. Then the energy eigenvalues of IMFs are used as inputs to construct SVM classification model. At last, the classification model is used to distinguish the types of bearing faults. In bearing fault diagnosis experiment, AEEMD and EEMD are compared to prove that AEEMD decomposition is better, and then diagnostic performance of BP neural network and SVM is also analyzed comparatively. The result shows that the method proposed in this paper can diagnose bearing faults more quickly and accurately.
In order to solve the problems that white noise parameters need artificial selection in EEMD (ensemble empirical mode decomposition) and considering the situation that plenty of samples of typical faults are difficult to obtain in reality, an bearing fault diagnosis method based on adaptive EEMD (AEEMD) and SVM (support vector machine) is proposed. First of all, AEEMD is used to decompose the vibration signal into several IMFs (intrinsic mode functions) of different characteristic time scales in signal processing. To different bearing faults, the energy of signals in different frequency bands can change, so energy of IMFs can be used to realize fault feature extraction. Then the energy eigenvalues of IMFs are used as inputs to construct SVM classification model. At last, the classification model is used to distinguish the types of bearing faults. In bearing fault diagnosis experiment, AEEMD and EEMD are compared to prove that AEEMD decomposition is better, and then diagnostic performance of BP neural network and SVM is also analyzed comparatively. The result shows that the method proposed in this paper can diagnose bearing faults more quickly and accurately.
2016, 35(11): 1733-1737.
doi: 10.13433/j.cnki.1003-8728.2016.1116
Abstract:
The modal parameter estimation method based on the autoregressive (AR) modal may produce inaccurate modal parameters as well as a fake modal or miss some modals because of wrong orders. To solve this problem, this paper comes up with a new method by solving the coefficients of vibration mode with a sparse constraint so as to produce accurate modal parameters. It first uses the AR model to arrive at the modal parameters by assuming a larger order for the vibration mode and then constructs the sparse optimization model for the coefficient of vibration mode. After that, the statistical results obtained with the multiple solutions for the sparse optimization model are used to adjust the final results. Finally, the paper identifies modal parameters according to the coefficient of vibration mode. This method not only avoids the errors caused by assuming the large order but also enhances noise resistance. The test results on the cable demonstrate the stability and accuracy of this method.
The modal parameter estimation method based on the autoregressive (AR) modal may produce inaccurate modal parameters as well as a fake modal or miss some modals because of wrong orders. To solve this problem, this paper comes up with a new method by solving the coefficients of vibration mode with a sparse constraint so as to produce accurate modal parameters. It first uses the AR model to arrive at the modal parameters by assuming a larger order for the vibration mode and then constructs the sparse optimization model for the coefficient of vibration mode. After that, the statistical results obtained with the multiple solutions for the sparse optimization model are used to adjust the final results. Finally, the paper identifies modal parameters according to the coefficient of vibration mode. This method not only avoids the errors caused by assuming the large order but also enhances noise resistance. The test results on the cable demonstrate the stability and accuracy of this method.
2016, 35(11): 1738-1744.
doi: 10.13433/j.cnki.1003-8728.2016.1117
Abstract:
Aimed at the deficiencies of the single contact forms, limited experiment scope and inconsistent boundary condition in the research on tribology apparatus, a multifunctional tribology and transmission machine is developed under the consistent boundary condition. Employing two independent actuators which can make the relative motion to drive main shafts, it is allowable for various test pieces and thus can perform a series of tribology and transmission tests including friction, wear, transmission performance, contact fatigue under consistent boundary condition. The experimental investigation indicates that the machine provides a fundamental platforms for an interface friction, lubrication mechanisms, mechanics model,and kinematics analysis of transmission system, which meets the requirements.
Aimed at the deficiencies of the single contact forms, limited experiment scope and inconsistent boundary condition in the research on tribology apparatus, a multifunctional tribology and transmission machine is developed under the consistent boundary condition. Employing two independent actuators which can make the relative motion to drive main shafts, it is allowable for various test pieces and thus can perform a series of tribology and transmission tests including friction, wear, transmission performance, contact fatigue under consistent boundary condition. The experimental investigation indicates that the machine provides a fundamental platforms for an interface friction, lubrication mechanisms, mechanics model,and kinematics analysis of transmission system, which meets the requirements.
2016, 35(11): 1745-1750.
doi: 10.13433/j.cnki.1003-8728.2016.1118
Abstract:
In order to study the fatigue life of dump truck under an actual working condition, the finite element static analysis of frame under different load conditions has been done by using the inertial release method. Based on the above analysis, the stress response factor on the key positions of frame has been obtained by using the quasi-static stress analysis. According to the linear cumulative damage theory and the loads proportion, the fatigue life has been calculated combining the S-N curve of frame materials. The results show that all the maximum stress is below the yield limit of frame material, the errors between the simulation frame stress value and the experimental are less than 12%, which meet the strength requirements. The fatigue life of frame under full load condition is more than 16 814 hours, which basically meet the requirements of service life.
In order to study the fatigue life of dump truck under an actual working condition, the finite element static analysis of frame under different load conditions has been done by using the inertial release method. Based on the above analysis, the stress response factor on the key positions of frame has been obtained by using the quasi-static stress analysis. According to the linear cumulative damage theory and the loads proportion, the fatigue life has been calculated combining the S-N curve of frame materials. The results show that all the maximum stress is below the yield limit of frame material, the errors between the simulation frame stress value and the experimental are less than 12%, which meet the strength requirements. The fatigue life of frame under full load condition is more than 16 814 hours, which basically meet the requirements of service life.
2016, 35(11): 1751-1755.
doi: 10.13433/j.cnki.1003-8728.2016.1119
Abstract:
At present HEV(Hybrid Electric Vehicle) research mainly focuses on the single object such as fuel economy, but little for multi-objectives. Taking the parallel HEV with 5 gears manual transmission as the research object, a multi-objectives evolutionary algorithm (MOEA) based on non-dominated sorting is proposed, which can analyze the influence of transmission ratio match on the fuel economy and emissions. The simulation results show that fuel economy increases by 3.09% and the emission performance comprehensive index increases by 17.92% compared with the pre-optimization results, which improves the effect of energy conservation. Moreover, the obtained Pareto solution sets have good distribution and convergence, which not only optimizes the objectives, but also reflects the conflict conditions among the objectives. The results show that the proposed MOEA can embody the essence of multi-objectives optimization for HEV. The overall optimal solution set, which can be searched theoretically, provides the ideal control basis for HEV multi-objectives trade-off control strategy.
At present HEV(Hybrid Electric Vehicle) research mainly focuses on the single object such as fuel economy, but little for multi-objectives. Taking the parallel HEV with 5 gears manual transmission as the research object, a multi-objectives evolutionary algorithm (MOEA) based on non-dominated sorting is proposed, which can analyze the influence of transmission ratio match on the fuel economy and emissions. The simulation results show that fuel economy increases by 3.09% and the emission performance comprehensive index increases by 17.92% compared with the pre-optimization results, which improves the effect of energy conservation. Moreover, the obtained Pareto solution sets have good distribution and convergence, which not only optimizes the objectives, but also reflects the conflict conditions among the objectives. The results show that the proposed MOEA can embody the essence of multi-objectives optimization for HEV. The overall optimal solution set, which can be searched theoretically, provides the ideal control basis for HEV multi-objectives trade-off control strategy.
2016, 35(11): 1756-1760.
doi: 10.13433/j.cnki.1003-8728.2016.1120
Abstract:
Based on the detailed presentation of the structure and working principles of a time-sharing all-wheel-drive car, we propose its transfer case's multiobjective optimization design method based on the multi-population genetic algorithms. In this paper, a transfer case optimization mathematical model was set up by using maximum climbable gradients, fuel economy and gear contact ratio, using MATLAB software for the optimization design. At the same time, the AVL Cruise software was used for the virtual simulation of the vehicle. The simulation results show that the optimized vehicle's maximum climbable gradient is 2.78 degrees lower, that its fuel consumption is 12.52% lower and that its planetary gear contact ratio increases by 8.62%. The experimental results are consistent with the optimization results and verify their correctness.
Based on the detailed presentation of the structure and working principles of a time-sharing all-wheel-drive car, we propose its transfer case's multiobjective optimization design method based on the multi-population genetic algorithms. In this paper, a transfer case optimization mathematical model was set up by using maximum climbable gradients, fuel economy and gear contact ratio, using MATLAB software for the optimization design. At the same time, the AVL Cruise software was used for the virtual simulation of the vehicle. The simulation results show that the optimized vehicle's maximum climbable gradient is 2.78 degrees lower, that its fuel consumption is 12.52% lower and that its planetary gear contact ratio increases by 8.62%. The experimental results are consistent with the optimization results and verify their correctness.
2016, 35(11): 1761-1767.
doi: 10.13433/j.cnki.1003-8728.2016.1121
Abstract:
In order to improve the steering control performance of four wheels independent steering (4WIS) vehicle, a two-degree of freedom dynamics model of 4WIS vehicle is established and the angle relationship between the four wheels and reference wheel is solved. The kinematics model of four wheels is built in the vehicle coordinate system, and the real-time kinematics error is obtained by solving the instantaneous center of rotation (ICR) of vehicle. Based on these models, a kind strategy named dynamics and kinematics compound control is proposed, the constraint relationship of steering angle between four wheels and reference wheel is got according to the dynamics calculation, through the network control system each wheel tracking the target trajectory independently and simultaneously, so the response speed of the steering control system is improved. The virtual connection of each wheel steering angle is established by real-time kinematical error, so the stability and robustness of steering control is improved by four wheels real-time coordinated motion. The simulation results show that vehicle dynamics requirements are met through the coordination control of wheels. At last, the experimental results show that the control strategy is effective.
In order to improve the steering control performance of four wheels independent steering (4WIS) vehicle, a two-degree of freedom dynamics model of 4WIS vehicle is established and the angle relationship between the four wheels and reference wheel is solved. The kinematics model of four wheels is built in the vehicle coordinate system, and the real-time kinematics error is obtained by solving the instantaneous center of rotation (ICR) of vehicle. Based on these models, a kind strategy named dynamics and kinematics compound control is proposed, the constraint relationship of steering angle between four wheels and reference wheel is got according to the dynamics calculation, through the network control system each wheel tracking the target trajectory independently and simultaneously, so the response speed of the steering control system is improved. The virtual connection of each wheel steering angle is established by real-time kinematical error, so the stability and robustness of steering control is improved by four wheels real-time coordinated motion. The simulation results show that vehicle dynamics requirements are met through the coordination control of wheels. At last, the experimental results show that the control strategy is effective.
2016, 35(11): 1768-1773.
doi: 10.13433/j.cnki.1003-8728.2016.1122
Abstract:
The influence of the combined brake of motor and retarder's on the braking performance was investigated. Based on the ideal braking force distribution curves between front and rear arresters, the new braking force distribution curves including motor and retarder's braking force was derived. The utilization ratio of braking force reflecting braking performance was an important evaluationg indicator. For a mini-bus, the relationship between the braking force utilization ratio and the motor's speed was analyzed. The results indicate that at the low grade of retarder working, the braking force utilization ratio is proportional to motor's speed for the wet or slippery road braking, also the braking force utilization ratio is inversely proportional to motor's speed for the dry road braking. Secondly, at the high grade of retarder working, the braking force utilization reatio is inversely proportional to motor's speed for all kind of roads braking.
The influence of the combined brake of motor and retarder's on the braking performance was investigated. Based on the ideal braking force distribution curves between front and rear arresters, the new braking force distribution curves including motor and retarder's braking force was derived. The utilization ratio of braking force reflecting braking performance was an important evaluationg indicator. For a mini-bus, the relationship between the braking force utilization ratio and the motor's speed was analyzed. The results indicate that at the low grade of retarder working, the braking force utilization ratio is proportional to motor's speed for the wet or slippery road braking, also the braking force utilization ratio is inversely proportional to motor's speed for the dry road braking. Secondly, at the high grade of retarder working, the braking force utilization reatio is inversely proportional to motor's speed for all kind of roads braking.
2016, 35(11): 1774-1779.
doi: 10.13433/j.cnki.1003-8728.2016.1123
Abstract:
An analysis method of key parameters on aircraft engines bird ingestion Airworthiness certification was suggested. Based on the critical parameters analysis, the synthesized key impact parameter (SCIP) method was presented to estimate bird-impact damage and determine certification critical ingestion parameters (CIP). Meanwhile, the finite element model for bird impact on rotating fan blades was established by using SPH method, and the numerical simulations of the bird-impact were carried out. The influences of parameters such as bird ingestion speed, rotating speed of fan, impact location were studied, and the SCIP values under different conditions were obtained. It is concluded that the bird-impact damage is the most serious on the condition of CIP=F(72 m/s,70%,100%). Consequently, a set of CIP for bird ingestion airworthiness certification test was confirmed.
An analysis method of key parameters on aircraft engines bird ingestion Airworthiness certification was suggested. Based on the critical parameters analysis, the synthesized key impact parameter (SCIP) method was presented to estimate bird-impact damage and determine certification critical ingestion parameters (CIP). Meanwhile, the finite element model for bird impact on rotating fan blades was established by using SPH method, and the numerical simulations of the bird-impact were carried out. The influences of parameters such as bird ingestion speed, rotating speed of fan, impact location were studied, and the SCIP values under different conditions were obtained. It is concluded that the bird-impact damage is the most serious on the condition of CIP=F(72 m/s,70%,100%). Consequently, a set of CIP for bird ingestion airworthiness certification test was confirmed.
2016, 35(11): 1780-1784.
doi: 10.13433/j.cnki.1003-8728.2016.1124
Abstract:
To study the mobility property and provide a method to optimize the design of spacesuit isotensoid joint. On the basis of existing joint finite element analysis, a finite element (FE) model of spacesuit isotensoid joint was established by using Lsdyna code according to the principle of equipment for testing flexible single-axis joint. Then the motion morphology of the joint was analyzed, and the joint torque-angle relationship was calculated. Experiment was conducted to verify this model. The results show that the accuracy of isotensoid joint FE model is improved compared to that of the existing model. The present model can exactly reflect the real changes of joint geometry during motion. And the torque-angle relationship calculated is basically the same as that experimentally measured. In the testing angle range of 0 to 80 degrees, joint torque is relatively low. The isotensoid joint demonstrates high flexibility and the present FE model can be further used for optimization design of the joint.
To study the mobility property and provide a method to optimize the design of spacesuit isotensoid joint. On the basis of existing joint finite element analysis, a finite element (FE) model of spacesuit isotensoid joint was established by using Lsdyna code according to the principle of equipment for testing flexible single-axis joint. Then the motion morphology of the joint was analyzed, and the joint torque-angle relationship was calculated. Experiment was conducted to verify this model. The results show that the accuracy of isotensoid joint FE model is improved compared to that of the existing model. The present model can exactly reflect the real changes of joint geometry during motion. And the torque-angle relationship calculated is basically the same as that experimentally measured. In the testing angle range of 0 to 80 degrees, joint torque is relatively low. The isotensoid joint demonstrates high flexibility and the present FE model can be further used for optimization design of the joint.
2016, 35(11): 1785-1790.
doi: 10.13433/j.cnki.1003-8728.2016.1125
Abstract:
Axisymmetric vector nozzle throat area has an important influence on the nozzle performance. Generally the inscribed circle of convergence adjusting piece end represents the throat area. Different errors exist for different number of adjusting piece, and the accuracy is not high enough for further quantitative analysis. In this paper, the characteristics of throat polygon were studied and the exact expression of throat area was deduced. The kinematic model of throat circle was established by utilizing cam inversion method and coordinates transformation. Numerical calculation and virtual simulation were conducted and compared for an example. The results of the numerical calculation and the virtual simulation agree well and the maximum relative error is 0.79%. It demonstrates the correctness of the established kinematic model of throat.
Axisymmetric vector nozzle throat area has an important influence on the nozzle performance. Generally the inscribed circle of convergence adjusting piece end represents the throat area. Different errors exist for different number of adjusting piece, and the accuracy is not high enough for further quantitative analysis. In this paper, the characteristics of throat polygon were studied and the exact expression of throat area was deduced. The kinematic model of throat circle was established by utilizing cam inversion method and coordinates transformation. Numerical calculation and virtual simulation were conducted and compared for an example. The results of the numerical calculation and the virtual simulation agree well and the maximum relative error is 0.79%. It demonstrates the correctness of the established kinematic model of throat.
2016, 35(11): 1791-1796.
doi: 10.13433/j.cnki.1003-8728.2016.1126
Abstract:
Based on the application requirement of offset-fed truss antenna, a truss reflector with one edge constrained is proposed. Considering the hexagonal outline characteristics of the truss reflector, the overall configuration design is performed, and the detail configurations of the reflector parts are confirmed with local coordinates approach. Then, the configuration design method of offset-fed truss reflector is formed. According to certain antenna parameters, the configuration design of the truss reflector with 5.5 m diameter is performed. The deployment simulation and ground test are carried out, which demonstrate the feasibility of proposed design method.
Based on the application requirement of offset-fed truss antenna, a truss reflector with one edge constrained is proposed. Considering the hexagonal outline characteristics of the truss reflector, the overall configuration design is performed, and the detail configurations of the reflector parts are confirmed with local coordinates approach. Then, the configuration design method of offset-fed truss reflector is formed. According to certain antenna parameters, the configuration design of the truss reflector with 5.5 m diameter is performed. The deployment simulation and ground test are carried out, which demonstrate the feasibility of proposed design method.
2016, 35(11): 1797-1804.
doi: 10.13433/j.cnki.1003-8728.2016.1127
Abstract:
Regarding the flexibility of airframe and landing-gear strut, and taking the carrier as reference frame, the multi-body dynamics model of carrier-based airframe was established. For the first time, the dynamics equations of carrier-based aircraft were extended to non-inertial reference frame. By increasing the simulation procedure of free parking and tension parking, it had the full-process simulation capacity for catapult launch. The validity of the model was verified by a simulation example. The study on the effects of elevator angle and deck motion indicated that:by the aid of the gear fast extension, the nose-up pitching moment caused by elevator angle before flying off can increase pitch angle and pitch rate greatly at the flying-off time; besides speeding up the construction of angle of attack(AOA), the control law for after flying-off elevator angle also control the maximum AOA during climbing, which is conductive to the safety of catapult launch; through the bow vertical velocity, rate of pitch and projecting angle of carrier, the deck motion have significant influence on the after flying-off flight performance. Deck motion endangers the safety of catapult launch of carrier-based aircraft; among the deck motions, the roll motion and pitch motion are more serious.
Regarding the flexibility of airframe and landing-gear strut, and taking the carrier as reference frame, the multi-body dynamics model of carrier-based airframe was established. For the first time, the dynamics equations of carrier-based aircraft were extended to non-inertial reference frame. By increasing the simulation procedure of free parking and tension parking, it had the full-process simulation capacity for catapult launch. The validity of the model was verified by a simulation example. The study on the effects of elevator angle and deck motion indicated that:by the aid of the gear fast extension, the nose-up pitching moment caused by elevator angle before flying off can increase pitch angle and pitch rate greatly at the flying-off time; besides speeding up the construction of angle of attack(AOA), the control law for after flying-off elevator angle also control the maximum AOA during climbing, which is conductive to the safety of catapult launch; through the bow vertical velocity, rate of pitch and projecting angle of carrier, the deck motion have significant influence on the after flying-off flight performance. Deck motion endangers the safety of catapult launch of carrier-based aircraft; among the deck motions, the roll motion and pitch motion are more serious.
