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RSS2017 Vol. 36, No. 10
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2017, 36(10): 1477-1483.
doi: 10.13433/j.cnki.1003-8728.2017.1001
PDF 1034KB
Abstract:
On the research of exhaust waste heat recovery by using Rankine cycle,a type of evaporator with multi-layer spiral tubes is proposed. A mathematical model is generated to evaluate the performance of the evaporator according to its structure parameters and working characteristics. Based on this model, start-stop parameters of each heat transfer section is analyzed. The simulation results show that the increases of the mass flow rate of the working fluid can lead to a reduced outlet temperature of working fluid and exhaust while the exhaust energy utilization rate is increased. The heat transfer area can limit the increase of the mass flow rate of the working fluid and superheat. To evaluate the performance of evaporator, the Rankine cycle waste heat recovery system is established and tested. The test results indicate that the maximum efficiency of evaporator is 89.33% and the maximum actual exhaust energy utilization rate is 41.93%.
On the research of exhaust waste heat recovery by using Rankine cycle,a type of evaporator with multi-layer spiral tubes is proposed. A mathematical model is generated to evaluate the performance of the evaporator according to its structure parameters and working characteristics. Based on this model, start-stop parameters of each heat transfer section is analyzed. The simulation results show that the increases of the mass flow rate of the working fluid can lead to a reduced outlet temperature of working fluid and exhaust while the exhaust energy utilization rate is increased. The heat transfer area can limit the increase of the mass flow rate of the working fluid and superheat. To evaluate the performance of evaporator, the Rankine cycle waste heat recovery system is established and tested. The test results indicate that the maximum efficiency of evaporator is 89.33% and the maximum actual exhaust energy utilization rate is 41.93%.
2017, 36(10): 1484-1490.
doi: 10.13433/j.cnki.1003-8728.2017.1002
Abstract:
The problem of low efficiency of vibration energy collection in the environment is the focus of the research on piezoelectric power generation technology. In order to improve the collection efficiency of the vibration energy in the environment, the piezoelectric power generation technology for multi-direction collecting environment vibration energy is studied. First, the mathematical model of the piezoelectric cantilever is built by the basic theory of the piezoelectric power generation technology, and the vibration mechanics analysis is carried out. Then, the piezoelectric cantilever is analyzed using ANSYS finite element simulation, and the structure is optimized so that the natural frequency of the vibration frequency is consistent with the environment. And finally, the multi-direction piezoelectric device is developed, and its theoretical analysis and experimental testing are finished. The experimental results show that the multi-direction vibration of piezoelectric power generation key technologies can effectively improve the collection efficiency of vibration energy.
The problem of low efficiency of vibration energy collection in the environment is the focus of the research on piezoelectric power generation technology. In order to improve the collection efficiency of the vibration energy in the environment, the piezoelectric power generation technology for multi-direction collecting environment vibration energy is studied. First, the mathematical model of the piezoelectric cantilever is built by the basic theory of the piezoelectric power generation technology, and the vibration mechanics analysis is carried out. Then, the piezoelectric cantilever is analyzed using ANSYS finite element simulation, and the structure is optimized so that the natural frequency of the vibration frequency is consistent with the environment. And finally, the multi-direction piezoelectric device is developed, and its theoretical analysis and experimental testing are finished. The experimental results show that the multi-direction vibration of piezoelectric power generation key technologies can effectively improve the collection efficiency of vibration energy.
2017, 36(10): 1491-1497.
doi: 10.13433/j.cnki.1003-8728.2017.1003
Abstract:
The flow under different Reynolds number Re and different radius ratio Rc/D in 90° arc bend pipe was simulated with the numerical RNG k-ε turbulence model in the software FLUENT. The velocity distribution, pressure distribution and the secondary vortex flow inside the bend pipe were analyzed. The local drag coefficient, the effects of the length of local drag on 72 working conditions with different Reynolds numbers Re (1×104 ≤ Re ≤ 1×106) and different radius ratios Rc/D (0.6 ≤ Rc/D ≤ 2) were analyzed. It is found that Re is constant, the local drag coefficient is reduced when Rc/D increases. Rc/D is constant; Re ≤ 6×105; the local drag coefficient decreases quickly when Re increases; Re≧6×105; the local drag coefficient change with that of Re is very small. Re is constant; the greater Rc/D, the shorter the length of local drag influence. The effect of the length of local drag influence on the increase of Re is reduced and then reaches a constant value; the less Rc/D, the more delay, the longer it takes for the local drag coefficient to reach a constant value.
The flow under different Reynolds number Re and different radius ratio Rc/D in 90° arc bend pipe was simulated with the numerical RNG k-ε turbulence model in the software FLUENT. The velocity distribution, pressure distribution and the secondary vortex flow inside the bend pipe were analyzed. The local drag coefficient, the effects of the length of local drag on 72 working conditions with different Reynolds numbers Re (1×104 ≤ Re ≤ 1×106) and different radius ratios Rc/D (0.6 ≤ Rc/D ≤ 2) were analyzed. It is found that Re is constant, the local drag coefficient is reduced when Rc/D increases. Rc/D is constant; Re ≤ 6×105; the local drag coefficient decreases quickly when Re increases; Re≧6×105; the local drag coefficient change with that of Re is very small. Re is constant; the greater Rc/D, the shorter the length of local drag influence. The effect of the length of local drag influence on the increase of Re is reduced and then reaches a constant value; the less Rc/D, the more delay, the longer it takes for the local drag coefficient to reach a constant value.
2017, 36(10): 1498-1504.
doi: 10.13433/j.cnki.1003-8728.2017.1004
Abstract:
The fuel consumption fee of drilling diesel is more than 30% of the cost in drilling engineering, diesel emission has been primary pollution source. In this paper, taking the real structure data and the experiment data of the 190 series diesel engine from Jinan diesel manufacturer to build a Dual-Stage turbocharger diesel model, the arrangement of two stage turbocharger was determined through the comparison and analysis. The results showed that the dynamic performance and acceleration performance, emission performance, fuel economy and efficiency of turbocharger were remarkably improved comparing with the origin engine.
The fuel consumption fee of drilling diesel is more than 30% of the cost in drilling engineering, diesel emission has been primary pollution source. In this paper, taking the real structure data and the experiment data of the 190 series diesel engine from Jinan diesel manufacturer to build a Dual-Stage turbocharger diesel model, the arrangement of two stage turbocharger was determined through the comparison and analysis. The results showed that the dynamic performance and acceleration performance, emission performance, fuel economy and efficiency of turbocharger were remarkably improved comparing with the origin engine.
2017, 36(10): 1505-1511.
doi: 10.13433/j.cnki.1003-8728.2017.1005
Abstract:
Due to the fact that there may be trade-offs among ride comfort, suspension deflection and tire deformation for the active suspension system, and considering the robustness of control system with parameter uncertainties and external disturbances, an active suspension controller based on nonlinear filtering method and the sliding mode variable structure control method was designed in order to comprehensively improve the suspension system performance. According to the previously established control algorithm, implementation of the control system requires real-time access to several key states, a state observer was proposed using the extended Kalman filter method. Subsequently, simulation schemes including random road excitation, sinusoidal road excitation and bump road excitation are carried out to validate the effectiveness of the entire control system. The results of the simulations show that, the proposed control system has good road adaptability, and can effectively improve ride comfort and road holding performance without sacrificing suspension deflection. Therefore, the proposed control system is beneficial to improve the ride quality and handling stability of vehicle.
Due to the fact that there may be trade-offs among ride comfort, suspension deflection and tire deformation for the active suspension system, and considering the robustness of control system with parameter uncertainties and external disturbances, an active suspension controller based on nonlinear filtering method and the sliding mode variable structure control method was designed in order to comprehensively improve the suspension system performance. According to the previously established control algorithm, implementation of the control system requires real-time access to several key states, a state observer was proposed using the extended Kalman filter method. Subsequently, simulation schemes including random road excitation, sinusoidal road excitation and bump road excitation are carried out to validate the effectiveness of the entire control system. The results of the simulations show that, the proposed control system has good road adaptability, and can effectively improve ride comfort and road holding performance without sacrificing suspension deflection. Therefore, the proposed control system is beneficial to improve the ride quality and handling stability of vehicle.
2017, 36(10): 1512-1520.
doi: 10.13433/j.cnki.1003-8728.2017.1006
Abstract:
In order to overcome the complex process, poor regularity, difficulty in implementation in any time and any place to calculate the load spectrum of a conventional scraper conveyor, we establish a new mathematical model for calculating the load spectrum of a scraper conveyor with the help of computer numerical method. The model uses a one-dimensional array to simulate the scraper conveyor through numerically simulating the changes of each element in the array that correspond to the changes in the load of the scraper conveyor with the coal mining machine position change. The MATLAB software is used to develop the software platform of the scraper conveyor's load spectrum simulation system to avoid the tedious data input process. Through computer simulation, this paper compares the method with the conventional method, and the simulation results verify its feasibility and advantage. This method can greatly simplify the calculation process of the load spectrum of the scraper conveyor and can obtain cargo distribution at any time and position of the scraper conveyor. The method provides the database for the running resistance of the dynamic characteristics of the scraper conveyor, the tension variation and the real time adjustment.
In order to overcome the complex process, poor regularity, difficulty in implementation in any time and any place to calculate the load spectrum of a conventional scraper conveyor, we establish a new mathematical model for calculating the load spectrum of a scraper conveyor with the help of computer numerical method. The model uses a one-dimensional array to simulate the scraper conveyor through numerically simulating the changes of each element in the array that correspond to the changes in the load of the scraper conveyor with the coal mining machine position change. The MATLAB software is used to develop the software platform of the scraper conveyor's load spectrum simulation system to avoid the tedious data input process. Through computer simulation, this paper compares the method with the conventional method, and the simulation results verify its feasibility and advantage. This method can greatly simplify the calculation process of the load spectrum of the scraper conveyor and can obtain cargo distribution at any time and position of the scraper conveyor. The method provides the database for the running resistance of the dynamic characteristics of the scraper conveyor, the tension variation and the real time adjustment.
2017, 36(10): 1521-1529.
doi: 10.13433/j.cnki.1003-8728.2017.1007
Abstract:
For mobile robot path planning based on traditional artificial potential field, the avoidance to movable obstacle is inefficient and there are local minima in the generated path. To solve this problem, an improved potential field model based on potential flow theory is proposed. In the improved model, the corresponding relationship between potential flow theory and path planning is introduced. Conflicts, for instance that velocity is infinite in the position of sink, are resolved by modified function. To satisfy the reliability of avoiding mobile obstacle, Zhukovsky transformation is used to optimize the configuration and function of potential model. A further investigation of vortex is applied to prevent the local minima. After that, the concept of virtual source is introduced for path planner to generate an optimized trajectory. In the end, the issue of multi-obstacle potential superposition is discussed. To verify the algorithm, comparisons between improved method and traditional one by various circumstances in simulation are conducted. The simulation results indicate that in the improved method, potential field is able to lead robot to avoid mobile obstacles according to velocity vectors of obstacles. Besides, the method is more efficient when preventing local minima.
For mobile robot path planning based on traditional artificial potential field, the avoidance to movable obstacle is inefficient and there are local minima in the generated path. To solve this problem, an improved potential field model based on potential flow theory is proposed. In the improved model, the corresponding relationship between potential flow theory and path planning is introduced. Conflicts, for instance that velocity is infinite in the position of sink, are resolved by modified function. To satisfy the reliability of avoiding mobile obstacle, Zhukovsky transformation is used to optimize the configuration and function of potential model. A further investigation of vortex is applied to prevent the local minima. After that, the concept of virtual source is introduced for path planner to generate an optimized trajectory. In the end, the issue of multi-obstacle potential superposition is discussed. To verify the algorithm, comparisons between improved method and traditional one by various circumstances in simulation are conducted. The simulation results indicate that in the improved method, potential field is able to lead robot to avoid mobile obstacles according to velocity vectors of obstacles. Besides, the method is more efficient when preventing local minima.
2017, 36(10): 1530-1535.
doi: 10.13433/j.cnki.1003-8728.2017.1008
Abstract:
A novel leg-toe type pipeline robot based on the parallel mechanism was proposed. The robot has adopted the parallel mechanism as the moving-carrier and the connecting rod type leg-toe mechanism as the walking device. A solid model for robot was built, and its working principle and characteristics was explained. By using the vector method and the principle of virtual work, the kinematics and statics formulae were derived for solving the active force of the foot mechanism and the active/constrained forces of the parallel manipulator. Finally, an numeric example was given for explaining the present kinematics and statics formulae. The robot has a strong obstacle-climbing ability and environment adaptability.
A novel leg-toe type pipeline robot based on the parallel mechanism was proposed. The robot has adopted the parallel mechanism as the moving-carrier and the connecting rod type leg-toe mechanism as the walking device. A solid model for robot was built, and its working principle and characteristics was explained. By using the vector method and the principle of virtual work, the kinematics and statics formulae were derived for solving the active force of the foot mechanism and the active/constrained forces of the parallel manipulator. Finally, an numeric example was given for explaining the present kinematics and statics formulae. The robot has a strong obstacle-climbing ability and environment adaptability.
2017, 36(10): 1536-1541.
doi: 10.13433/j.cnki.1003-8728.2017.1009
Abstract:
Compressed sensing is a new theory of signal acquisition and processing. Base on this theory, compressed data is acquired in the process of compression sampling. In this paper, it is studied that which features is extracted from the compressed data and how these features used for equipment state estimation. Firstly, compressed data is analyzed and the study tried to find the corresponding relationship between compression data and signal sparsity. A time-domain compression characteristics is proposed, and used to extracting characteristic information hidden in the compressed data. Rolling bearing is chosen and time-domain characteristic is used to estimate the operational conditions of the rolling bearing. The method is used to analyze the whole life data of rolling bearing. The results show that the time domain compression feature can accurately estimate the running state of rolling bearings, demonstrate the effectiveness of the proposed method.
Compressed sensing is a new theory of signal acquisition and processing. Base on this theory, compressed data is acquired in the process of compression sampling. In this paper, it is studied that which features is extracted from the compressed data and how these features used for equipment state estimation. Firstly, compressed data is analyzed and the study tried to find the corresponding relationship between compression data and signal sparsity. A time-domain compression characteristics is proposed, and used to extracting characteristic information hidden in the compressed data. Rolling bearing is chosen and time-domain characteristic is used to estimate the operational conditions of the rolling bearing. The method is used to analyze the whole life data of rolling bearing. The results show that the time domain compression feature can accurately estimate the running state of rolling bearings, demonstrate the effectiveness of the proposed method.
2017, 36(10): 1542-1549.
doi: 10.13433/j.cnki.1003-8728.2017.1010
Abstract:
To solve the problems that the large aluminum foam element entity impact test cost is higher and the numerical simulation computation is larger, based on the similarity theory, the large and small models for three types, including a frustum of cone type, four trustum of a pyramid type and six trustum of a pyramid type of aluminum foam elements were respectively established at the geometry size ratio of 3:1, the energy absorption similarity ratio in the impact process of large and small models were deduced via dimensional analysis. Finite element simulation via large and small models were proceeded and the entity impact tests of small models were applied. The results show that the energy absorption of small models between the entity tests and the finite element method results has little errors, verifying that LS-DYNA finite element method is feasible in axial impact process of aluminum foam. The energy absorption ratios between the large and small models in finite element simulation are respectively of 26.51, 27.18, 26.73, in accordance with the ratio 27:1 derived from the dimensional analysis, the results show that it's feasible to analyze the energy absorption characteristic of foam aluminum components under the axial impact condition based on similarity theory.
To solve the problems that the large aluminum foam element entity impact test cost is higher and the numerical simulation computation is larger, based on the similarity theory, the large and small models for three types, including a frustum of cone type, four trustum of a pyramid type and six trustum of a pyramid type of aluminum foam elements were respectively established at the geometry size ratio of 3:1, the energy absorption similarity ratio in the impact process of large and small models were deduced via dimensional analysis. Finite element simulation via large and small models were proceeded and the entity impact tests of small models were applied. The results show that the energy absorption of small models between the entity tests and the finite element method results has little errors, verifying that LS-DYNA finite element method is feasible in axial impact process of aluminum foam. The energy absorption ratios between the large and small models in finite element simulation are respectively of 26.51, 27.18, 26.73, in accordance with the ratio 27:1 derived from the dimensional analysis, the results show that it's feasible to analyze the energy absorption characteristic of foam aluminum components under the axial impact condition based on similarity theory.
2017, 36(10): 1550-1555.
doi: 10.13433/j.cnki.1003-8728.2017.1011
Abstract:
Aiming at the poor machinability of 300M ultra-high strength steel, the high speed cutting process of 300M ultra-high strength steel was studied by using finite element method. The cutting simulation model was established on the basis of the relevant experimental data. The chip deformation and the stress distribution of cutting area in cutting process were studied. The effects of the cutting speed and tool geometry on the cutting force and cutting temperature were also studied. The simulation results showed that the change trend of the simulation data were basically the same as the experimental data. The cutting temperature increased and the cutting force decreased following increased with the increasing of cutting speed. When the tool rake angle increased, both the cutting force and the cutting temperature decreased to a great extent and the maximum stress focused on the tip and the rake face. Both the cutting force and the cutting temperature slightly decreased when the tool back angle increased, but the extent of change was very small.
Aiming at the poor machinability of 300M ultra-high strength steel, the high speed cutting process of 300M ultra-high strength steel was studied by using finite element method. The cutting simulation model was established on the basis of the relevant experimental data. The chip deformation and the stress distribution of cutting area in cutting process were studied. The effects of the cutting speed and tool geometry on the cutting force and cutting temperature were also studied. The simulation results showed that the change trend of the simulation data were basically the same as the experimental data. The cutting temperature increased and the cutting force decreased following increased with the increasing of cutting speed. When the tool rake angle increased, both the cutting force and the cutting temperature decreased to a great extent and the maximum stress focused on the tip and the rake face. Both the cutting force and the cutting temperature slightly decreased when the tool back angle increased, but the extent of change was very small.
2017, 36(10): 1556-1561.
doi: 10.13433/j.cnki.1003-8728.2017.1012
Abstract:
The three-dimensional elliptical vibration assisted cutting (EVAC) device is a very potential manufacturing method with wide application prospect. The ability to obtain the best performance of the 3D EVAC is up to the performance of a 3D EVAC apparatus. The current 3D EVAC apparatus is limited by the output of a single elliptical trajectory and the narrow adjusting performance of the elliptical trajectory and so on. In order to improve the output performance of the 3D EVAC apparatus, this paper focuses on the generation of multiple elliptical vibration trajectories in the 3D EVAC apparatus and explores the method for optimizing the performances of the designed device such as layout and size. Firstly, the design of the 3D EVAC apparatus utilizes three structures perpendicular to each other and in the same form of the sub-chains and flexible hinges amplifier structure, the output track of adjustable 3D EVAC apparatus and the analysis of the 3D elliptical vibration trajectory. Secondly, the finite element method is used for static checking and transient dynamic analysis of the designed apparatus and verifies the trace output of the tool nose. Finally, according to the finite element analysis results, we analyze and optimize the size and layout parameters of the designed device by establishing the flexible hinge optimization model of the 3D EVAC, thus its optimal parameters are obtained.
The three-dimensional elliptical vibration assisted cutting (EVAC) device is a very potential manufacturing method with wide application prospect. The ability to obtain the best performance of the 3D EVAC is up to the performance of a 3D EVAC apparatus. The current 3D EVAC apparatus is limited by the output of a single elliptical trajectory and the narrow adjusting performance of the elliptical trajectory and so on. In order to improve the output performance of the 3D EVAC apparatus, this paper focuses on the generation of multiple elliptical vibration trajectories in the 3D EVAC apparatus and explores the method for optimizing the performances of the designed device such as layout and size. Firstly, the design of the 3D EVAC apparatus utilizes three structures perpendicular to each other and in the same form of the sub-chains and flexible hinges amplifier structure, the output track of adjustable 3D EVAC apparatus and the analysis of the 3D elliptical vibration trajectory. Secondly, the finite element method is used for static checking and transient dynamic analysis of the designed apparatus and verifies the trace output of the tool nose. Finally, according to the finite element analysis results, we analyze and optimize the size and layout parameters of the designed device by establishing the flexible hinge optimization model of the 3D EVAC, thus its optimal parameters are obtained.
2017, 36(10): 1562-1569.
doi: 10.13433/j.cnki.1003-8728.2017.1013
Abstract:
The equal height track is the main processing method of sheet metal incremental forming. Through the equal height track forming mode of existence problem analysis, a to Vector Adaptive spiral tool path generation algorithm based on STereo Lithography(STL) model patch method is proposed. By using vertex offset offset method of STL data model, to offset model of STL model by using adaptive slicing algorithm of calculation model and hierarchical surface intersection, and Z axis is parallel to the contour and the contour is discredited into numbered by point of adjacent contour interpolation is to adaptive spiral trajectory. Finally, the case shows that the shape of the spiral line can greatly shorten the forming time, which can avoid the surface quality caused by the cutter location in contour forming. In addition, in the test of the shape forming part, the trajectory generated by the algorithm can ensure the surface quality of the formed parts. the spiral forming trajectory generated by this algorithm can greatly reduce the forming time, which can avoid the surface quality problems caused by the tool head and the sheet metal. Meanwhile, double angle forming parts in different regions of the surface roughness of consistency and that adaptive spiral trajectory in forming into shape piece can avoid the contour forming surface roughness of diversity, in a unified into angular forming surface roughness on has broad application prospects.
The equal height track is the main processing method of sheet metal incremental forming. Through the equal height track forming mode of existence problem analysis, a to Vector Adaptive spiral tool path generation algorithm based on STereo Lithography(STL) model patch method is proposed. By using vertex offset offset method of STL data model, to offset model of STL model by using adaptive slicing algorithm of calculation model and hierarchical surface intersection, and Z axis is parallel to the contour and the contour is discredited into numbered by point of adjacent contour interpolation is to adaptive spiral trajectory. Finally, the case shows that the shape of the spiral line can greatly shorten the forming time, which can avoid the surface quality caused by the cutter location in contour forming. In addition, in the test of the shape forming part, the trajectory generated by the algorithm can ensure the surface quality of the formed parts. the spiral forming trajectory generated by this algorithm can greatly reduce the forming time, which can avoid the surface quality problems caused by the tool head and the sheet metal. Meanwhile, double angle forming parts in different regions of the surface roughness of consistency and that adaptive spiral trajectory in forming into shape piece can avoid the contour forming surface roughness of diversity, in a unified into angular forming surface roughness on has broad application prospects.
2017, 36(10): 1570-1574.
doi: 10.13433/j.cnki.1003-8728.2017.1014
Abstract:
The directivity is an important parameter for measuring the performance of the sound source. In order to study the relationship between directivity and the number of steps of stepped plate, four plates with one to four steps of the same frequency and base thickness are designed in this paper. The directivity of four stepped plates and the piston plates which have the same frequency and thickness with those four stepped plates are calculated. The result shows that, the stepped plates have the same main lobe as the piston plates, but the side lobes of the former are more than those of the later. For the given frequency and base thickness, with the increasing of the number of the steps (it means the plate with greater radius), the directivity is sharper; the experiment of fabricated stepped plates shows that the experimental results are in good agreement with the calculated ones.
The directivity is an important parameter for measuring the performance of the sound source. In order to study the relationship between directivity and the number of steps of stepped plate, four plates with one to four steps of the same frequency and base thickness are designed in this paper. The directivity of four stepped plates and the piston plates which have the same frequency and thickness with those four stepped plates are calculated. The result shows that, the stepped plates have the same main lobe as the piston plates, but the side lobes of the former are more than those of the later. For the given frequency and base thickness, with the increasing of the number of the steps (it means the plate with greater radius), the directivity is sharper; the experiment of fabricated stepped plates shows that the experimental results are in good agreement with the calculated ones.
2017, 36(10): 1575-1581.
doi: 10.13433/j.cnki.1003-8728.2017.1015
Abstract:
The poor surface quality of parts is one of the main factors that restrict the application of single point incremental forming (SPIF), in which the surface roughness is an important indicator to evaluate the surface quality. In this paper, taking the 45° pyramidal shape as the research object, the grey relational analysis based method was carried out to conduct the forming parameters optimization of multi-objective control of the surface quality of forming parts.In order to study the best surface quality performance of forming parameters by using less number of experiments. The Taguchi orthogonal table was carried out to experimental design, through the grey relational grade obtained from grey relational analysis determine optimal forming parameters, meanwhile the main significant factor that affect the surface quality can be found by the difference between the maximum and minimum value of the grey relational grade of the forming parameters. The experimental results have shown that the longitudinal and transverse surface roughness of forming parts can be effectively improved by this proposed approach.
The poor surface quality of parts is one of the main factors that restrict the application of single point incremental forming (SPIF), in which the surface roughness is an important indicator to evaluate the surface quality. In this paper, taking the 45° pyramidal shape as the research object, the grey relational analysis based method was carried out to conduct the forming parameters optimization of multi-objective control of the surface quality of forming parts.In order to study the best surface quality performance of forming parameters by using less number of experiments. The Taguchi orthogonal table was carried out to experimental design, through the grey relational grade obtained from grey relational analysis determine optimal forming parameters, meanwhile the main significant factor that affect the surface quality can be found by the difference between the maximum and minimum value of the grey relational grade of the forming parameters. The experimental results have shown that the longitudinal and transverse surface roughness of forming parts can be effectively improved by this proposed approach.
2017, 36(10): 1582-1588.
doi: 10.13433/j.cnki.1003-8728.2017.1016
Abstract:
The number of neighbors in traditional manifold learning is fixed, but it is unbefitting in fault detection. In order to solve this problem, a new fault detection method using sparse manifold clustering and embedding (SMCE) is presented in this paper. SMCE extracts the low dimension manifold structure from observation space with high dimension and nonlinearity by solving sparse optimization problem and finding neighbors automatically. The parameter selection of neighbors is converted to select penalty coefficient of sparse optimization problem. By means of SMCE, the vibration feature of bearing and gear is extracted and supervised and unsupervised fault detection is achieved. The experiment illustrates that this method is better to extract the internal structure of fault signal and to detect mechanical fault. The detection accuracy with spectral clustering and SVM is higher than 98%.
The number of neighbors in traditional manifold learning is fixed, but it is unbefitting in fault detection. In order to solve this problem, a new fault detection method using sparse manifold clustering and embedding (SMCE) is presented in this paper. SMCE extracts the low dimension manifold structure from observation space with high dimension and nonlinearity by solving sparse optimization problem and finding neighbors automatically. The parameter selection of neighbors is converted to select penalty coefficient of sparse optimization problem. By means of SMCE, the vibration feature of bearing and gear is extracted and supervised and unsupervised fault detection is achieved. The experiment illustrates that this method is better to extract the internal structure of fault signal and to detect mechanical fault. The detection accuracy with spectral clustering and SVM is higher than 98%.
2017, 36(10): 1589-1593.
doi: 10.13433/j.cnki.1003-8728.2017.1017
Abstract:
When the cone valve core material was selected for red copper in relief valve online detection system, the valve mechanical properties does not meet the design conditions. The research method of improving valve core mechanical properties was proposed by optimizing the structural parameters of mechanisms. Lists of test plans of mechanical properties simulation of valve core were scheduled by uniform design test method. By means of finite element method, uniform design test, dynamic response model and other methods, the sensitivity of each parameter to the optimization results was analyzed. The dynamic response model of multiple index function and structural parameters was solved. The structural parameters were optimized by using the index fingerprint and genetic algorithm. The optimization results of uniform design test and index fingerprint were compared. Results show that the results of uniform design test and index fingerprint are very close, uniform design test method is suited for optimization analysis of the valve core mechanical properties.
When the cone valve core material was selected for red copper in relief valve online detection system, the valve mechanical properties does not meet the design conditions. The research method of improving valve core mechanical properties was proposed by optimizing the structural parameters of mechanisms. Lists of test plans of mechanical properties simulation of valve core were scheduled by uniform design test method. By means of finite element method, uniform design test, dynamic response model and other methods, the sensitivity of each parameter to the optimization results was analyzed. The dynamic response model of multiple index function and structural parameters was solved. The structural parameters were optimized by using the index fingerprint and genetic algorithm. The optimization results of uniform design test and index fingerprint were compared. Results show that the results of uniform design test and index fingerprint are very close, uniform design test method is suited for optimization analysis of the valve core mechanical properties.
2017, 36(10): 1594-1597.
doi: 10.13433/j.cnki.1003-8728.2017.1018
Abstract:
To overcome the difficulty in extracting the weak features of a wind turbine under poor working conditions such as variable speed and load, lightning and thunder strike, sleet and hail, etc, this paper proposed a novel wind turbine's weak feature extraction method based on cross genetic optimized Mexican hat wavelet (MHW) method. This method uses deformation parameters to optimize the MHW shape. Then the cross genetic optimization algorithm is introduced to optimize the deformation parameters. The matching shape is used to do the continuous wavelet transform to extract the weak features. The analysis of the vibration signal of the gearbox of the wind turbine on a wind farm proves that the proposed method can not only suppress the background noise interruption but also effectively extract the wind turbine's weak features.
To overcome the difficulty in extracting the weak features of a wind turbine under poor working conditions such as variable speed and load, lightning and thunder strike, sleet and hail, etc, this paper proposed a novel wind turbine's weak feature extraction method based on cross genetic optimized Mexican hat wavelet (MHW) method. This method uses deformation parameters to optimize the MHW shape. Then the cross genetic optimization algorithm is introduced to optimize the deformation parameters. The matching shape is used to do the continuous wavelet transform to extract the weak features. The analysis of the vibration signal of the gearbox of the wind turbine on a wind farm proves that the proposed method can not only suppress the background noise interruption but also effectively extract the wind turbine's weak features.
2017, 36(10): 1598-1603.
doi: 10.13433/j.cnki.1003-8728.2017.1019
Abstract:
Four-wheel positioning parameters mainly include toe angle, camber angle, kingpin inclination angle and kingpin caster angle, etc. We chose a certain auto model as our analysis object, built the deviation analysis model and structural dynamics model of the front suspension with the help of three dimensional deviation analysis software called Teamcenter Visualization Mockup (VSA) and Automatic dynamic analysis of mechanical systems (Adams), trying to study the effect of auto parts manufacturing deviations to steering-wheel positioning parameters. The analysis results will help us find out the main influencing factors of the wheel positioning parameters, which has a good guidance and practical significance for the reasonable optimization of the key manufacturing deviations, which will bring the better control of the vehicle manufacturing cost and the improvement of vehicle performance.
Four-wheel positioning parameters mainly include toe angle, camber angle, kingpin inclination angle and kingpin caster angle, etc. We chose a certain auto model as our analysis object, built the deviation analysis model and structural dynamics model of the front suspension with the help of three dimensional deviation analysis software called Teamcenter Visualization Mockup (VSA) and Automatic dynamic analysis of mechanical systems (Adams), trying to study the effect of auto parts manufacturing deviations to steering-wheel positioning parameters. The analysis results will help us find out the main influencing factors of the wheel positioning parameters, which has a good guidance and practical significance for the reasonable optimization of the key manufacturing deviations, which will bring the better control of the vehicle manufacturing cost and the improvement of vehicle performance.
2017, 36(10): 1604-1610.
doi: 10.13433/j.cnki.1003-8728.2017.1020
Abstract:
Based on 3-element coupled pantograph-catenary dynamic model, using the differential geometry theory of nonlinear system and the differential homeomorphism transformation, a global input-output linearization model of pantograph-catenary coupled vibration system was established, and the global linearization active control strategy for pantograph-catenary system based on state feedback linearization was proposed. The parameter cluster could be optimized through the zero-poles configuration in typical control theory, and it can overcome the shortcomings of the existing active control strategies which need the empirical estimation of the critical parameters and the accumulation of the empirical knowledge. The research results show that:compared with the LQR optimum control strategy, the global state feedback linearization active control can achieve more than 30% decrease in contact force of pantograph-catenary system; in the meanwhile, a better tracing result for the expect contact force mean value can be achieved, and thus the advantage of the control strategy presented in this paper is verified.
Based on 3-element coupled pantograph-catenary dynamic model, using the differential geometry theory of nonlinear system and the differential homeomorphism transformation, a global input-output linearization model of pantograph-catenary coupled vibration system was established, and the global linearization active control strategy for pantograph-catenary system based on state feedback linearization was proposed. The parameter cluster could be optimized through the zero-poles configuration in typical control theory, and it can overcome the shortcomings of the existing active control strategies which need the empirical estimation of the critical parameters and the accumulation of the empirical knowledge. The research results show that:compared with the LQR optimum control strategy, the global state feedback linearization active control can achieve more than 30% decrease in contact force of pantograph-catenary system; in the meanwhile, a better tracing result for the expect contact force mean value can be achieved, and thus the advantage of the control strategy presented in this paper is verified.
2017, 36(10): 1611-1618.
doi: 10.13433/j.cnki.1003-8728.2017.1021
Abstract:
In order to study the transverse strength performance of fiber reinforced composite materials, the computational micromechanics and random disturbing method are used to establish the representative volume element with random fibers. The two dominate damage patterns, interfacial debonding and matrix plastic deformation, are simulated by cohesive zone traction-separation law and Drucker-Prager elastic-plastic model respectively, as well as ductile damage criteria to predict matrix damage initiation and fracture, and then the progressive damage process is obtained, which is compared with the experimental data. Furthermore, the influence of the interface stiffness, interface strength, interface fracture energy on the damage constitutive model for composites are analyzed.
In order to study the transverse strength performance of fiber reinforced composite materials, the computational micromechanics and random disturbing method are used to establish the representative volume element with random fibers. The two dominate damage patterns, interfacial debonding and matrix plastic deformation, are simulated by cohesive zone traction-separation law and Drucker-Prager elastic-plastic model respectively, as well as ductile damage criteria to predict matrix damage initiation and fracture, and then the progressive damage process is obtained, which is compared with the experimental data. Furthermore, the influence of the interface stiffness, interface strength, interface fracture energy on the damage constitutive model for composites are analyzed.
2017, 36(10): 1619-1625.
doi: 10.13433/j.cnki.1003-8728.2017.1022
Abstract:
In order to optimize the grinding parameters which affects the surface roughness and improve the corrosion resistance of Zr-4 alloy cladding tube, a surface roughness model is firstly established by applyingthe central composite design method and Design-Expert 8.0 software, which has a mapping relationship with the main parameters of grinding parameters, including belt speed, grinding pressure, belt feeding speed and tube rotation speed.Secondly, the optimization and reliability verification of the present model are also carried out. Finally, the optimal combination of grinding parameters is obtained by analyzing the effect of the grinding parameters on the surface roughness of tube. The verification experiments show that the surface roughness of the alloy tube can be controlled to be below 0.46 μm effectively by using the optimal combination grinding parameters.
In order to optimize the grinding parameters which affects the surface roughness and improve the corrosion resistance of Zr-4 alloy cladding tube, a surface roughness model is firstly established by applyingthe central composite design method and Design-Expert 8.0 software, which has a mapping relationship with the main parameters of grinding parameters, including belt speed, grinding pressure, belt feeding speed and tube rotation speed.Secondly, the optimization and reliability verification of the present model are also carried out. Finally, the optimal combination of grinding parameters is obtained by analyzing the effect of the grinding parameters on the surface roughness of tube. The verification experiments show that the surface roughness of the alloy tube can be controlled to be below 0.46 μm effectively by using the optimal combination grinding parameters.
2017, 36(10): 1626-1632.
doi: 10.13433/j.cnki.1003-8728.2017.1023
Abstract:
Residual stress distribution and size precision of parts are closely related to single point incremental forming process. Tacking the conical part as an example of1060 Aluminum plate, the residual stress directions are firstly defined, then the equivalent plastic strain and the residual stress are studied and the partition according to the residual stress distribution of the forming parts along the height direction are studied via ABAQUS software and experiments. The result shows that:the residual stress distribution can be accurately simulated by using 3D solid model, the residual stress is mainly concentrated in the formed zone, and the value of residual stress in vertical direction is small; the transverse residual stress is in bending transition region, planar elongation region and the deformation zone of the bottom from the inside to the outside are tension-compression, compression-tension, tension-compression, the longitudinal residual stress is from tensile stress to compressive stress.
Residual stress distribution and size precision of parts are closely related to single point incremental forming process. Tacking the conical part as an example of1060 Aluminum plate, the residual stress directions are firstly defined, then the equivalent plastic strain and the residual stress are studied and the partition according to the residual stress distribution of the forming parts along the height direction are studied via ABAQUS software and experiments. The result shows that:the residual stress distribution can be accurately simulated by using 3D solid model, the residual stress is mainly concentrated in the formed zone, and the value of residual stress in vertical direction is small; the transverse residual stress is in bending transition region, planar elongation region and the deformation zone of the bottom from the inside to the outside are tension-compression, compression-tension, tension-compression, the longitudinal residual stress is from tensile stress to compressive stress.
2017, 36(10): 1633-1640.
doi: 10.13433/j.cnki.1003-8728.2017.1024
Abstract:
In general, the liquid shim is used to compensate the small gaps between the composite components in the aircraft assembly. The single bolt connection of composite laminates as the object, one experiment were designed:the measurement of the strain of laminated plate, and two cases are considered in the process:using a liquid shim to compensate for the gap and without it; The finite element model was built and validated by using ABAQUS software. The calculation results are in a good agreement with the experimental. Under different liquid shim compensation parameters, the change in the stress of laminated plate, including laminates internal stress and interlaminar stress are studied based on the present model. The results show that:with the increasing of gap, the liquid shim is more significant to improve the stress distribution, reduce the stress amplitude, and enhance the ability to resist delamination; the three generations liquid shim have very little differences on laminates internal stress and interlaminar stress; laminates internal stress will be significantly improved if a substantial increase in the elastic modulus of the shim.
In general, the liquid shim is used to compensate the small gaps between the composite components in the aircraft assembly. The single bolt connection of composite laminates as the object, one experiment were designed:the measurement of the strain of laminated plate, and two cases are considered in the process:using a liquid shim to compensate for the gap and without it; The finite element model was built and validated by using ABAQUS software. The calculation results are in a good agreement with the experimental. Under different liquid shim compensation parameters, the change in the stress of laminated plate, including laminates internal stress and interlaminar stress are studied based on the present model. The results show that:with the increasing of gap, the liquid shim is more significant to improve the stress distribution, reduce the stress amplitude, and enhance the ability to resist delamination; the three generations liquid shim have very little differences on laminates internal stress and interlaminar stress; laminates internal stress will be significantly improved if a substantial increase in the elastic modulus of the shim.
