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RSS2022 Vol. 41, No. 12
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2022, 41(12): 1805-1814.
doi: 10.13433/j.cnki.1003-8728.20200527
PDF 8919KB
Abstract:
This paper investigated a homography-based visual servoing control of a legged mobile robot, which is equipped with a fixed monocular camera. The position of the robot relative to the target object is estimated using state variables constructed withthe elements of a homography matrix. Then, the robot can accuratelyarrive at the desired position without depth information. Compared with a wheeled mobile robot, the intermittent motion of a legged mobile robot directly affects its image processing accuracy and destabilizes the visual servoing control. To address this problem, kinematics of legging mechanisms is analyzed, and the mapping between the velocity of the robot and that of a motor is established to enable the controller to adjust the movement of the legged mobile robot more accurately. To address this problem, kinematics of the legged mechanism is analyzed, and the mapping between velocities of the robot and motor speeds is established to enable the controller to adjust the movement of the legged mobile robot more accurately. Considering the influence of the movement of the legged mechanism on visual feedback, an improved adaptive median filter is proposed to improve the accuracy of the position estimation. Furthermore, a sliding mode controller is designed, and the Lyapunov-based approach is used to analyze the stability of the control system. With the aid of the CoppeliaSim software, themodel of the robot is built to verifythe effectiveness of the proposed method.
This paper investigated a homography-based visual servoing control of a legged mobile robot, which is equipped with a fixed monocular camera. The position of the robot relative to the target object is estimated using state variables constructed withthe elements of a homography matrix. Then, the robot can accuratelyarrive at the desired position without depth information. Compared with a wheeled mobile robot, the intermittent motion of a legged mobile robot directly affects its image processing accuracy and destabilizes the visual servoing control. To address this problem, kinematics of legging mechanisms is analyzed, and the mapping between the velocity of the robot and that of a motor is established to enable the controller to adjust the movement of the legged mobile robot more accurately. To address this problem, kinematics of the legged mechanism is analyzed, and the mapping between velocities of the robot and motor speeds is established to enable the controller to adjust the movement of the legged mobile robot more accurately. Considering the influence of the movement of the legged mechanism on visual feedback, an improved adaptive median filter is proposed to improve the accuracy of the position estimation. Furthermore, a sliding mode controller is designed, and the Lyapunov-based approach is used to analyze the stability of the control system. With the aid of the CoppeliaSim software, themodel of the robot is built to verifythe effectiveness of the proposed method.
2022, 41(12): 1815-1821.
doi: 10.13433/j.cnki.1003-8728.20200542
Abstract:
Because of poor lubrication and friction and wear of the conrodbig-end bearing of a diesel engine, based on the design theory of bearing profile, the mathematical expression of catenary profile is established. Using the AVL power unit that builds a flexible multi-body dynamics model of the conrod, the influence of the catenary profile of the conrod big-end bearing on its lubrication characteristics was analyzed. The calculation results show that: when the radial variation of thecatenary profile gradually increases, the peak oil film pressure first decreases and then increases, the minimum oil film thickness first increases and then decreases, and the total friction power loss first decreases and then increases. When the catenary bushing with the radial variation of option 4 (variation 6 μm) is adopted, the minimum oil film thickness increases by 0.22 μm, the peak oil film pressure is reduced by 10.92 MPa, and the total frictional power loss is reduced by 0.28 kW, thus being useful toreduce the friction and wear power consumption of the conrod big-end bearing and to improve its overall lubrication performance. Through curve fitting analysis, the function relationship of the three evaluation parameters of minimum oil film thickness, peak oil film pressure and total friction power loss is obtained, providing a reference for the optimal design of lubrication characteristics of the conrod big-end bearing.
Because of poor lubrication and friction and wear of the conrodbig-end bearing of a diesel engine, based on the design theory of bearing profile, the mathematical expression of catenary profile is established. Using the AVL power unit that builds a flexible multi-body dynamics model of the conrod, the influence of the catenary profile of the conrod big-end bearing on its lubrication characteristics was analyzed. The calculation results show that: when the radial variation of thecatenary profile gradually increases, the peak oil film pressure first decreases and then increases, the minimum oil film thickness first increases and then decreases, and the total friction power loss first decreases and then increases. When the catenary bushing with the radial variation of option 4 (variation 6 μm) is adopted, the minimum oil film thickness increases by 0.22 μm, the peak oil film pressure is reduced by 10.92 MPa, and the total frictional power loss is reduced by 0.28 kW, thus being useful toreduce the friction and wear power consumption of the conrod big-end bearing and to improve its overall lubrication performance. Through curve fitting analysis, the function relationship of the three evaluation parameters of minimum oil film thickness, peak oil film pressure and total friction power loss is obtained, providing a reference for the optimal design of lubrication characteristics of the conrod big-end bearing.
2022, 41(12): 1822-1828.
doi: 10.13433/j.cnki.1003-8728.20200526
Abstract:
In order to solve the problem that the maximum correlation kurtosis deconvolution (MCKD) is unable to adaptively determine parameters due to its limited ability to specify periodic impact enhancement for bearing rolling element fault signals with weak response under strong noise interference, an improved MCKD fault diagnosis method was proposed in this paper. First, the high frequency component of fault response is obtained by wavelet multi-scale decomposition to make the impact component more prominent; then the optimal high-frequency component of fault signal is reselected by the maximum kurtosis criterion to reduce the noise interference; finally, the MCKD parameters are determined by wavelet variance adaptive. Bearing fault simulation and experimental data analysis show that this method can realize the fault diagnosis of bearing rolling element with weak response, and is suitable for the fault diagnosis of bearing inner and outer ringsunder strong noise interference.
In order to solve the problem that the maximum correlation kurtosis deconvolution (MCKD) is unable to adaptively determine parameters due to its limited ability to specify periodic impact enhancement for bearing rolling element fault signals with weak response under strong noise interference, an improved MCKD fault diagnosis method was proposed in this paper. First, the high frequency component of fault response is obtained by wavelet multi-scale decomposition to make the impact component more prominent; then the optimal high-frequency component of fault signal is reselected by the maximum kurtosis criterion to reduce the noise interference; finally, the MCKD parameters are determined by wavelet variance adaptive. Bearing fault simulation and experimental data analysis show that this method can realize the fault diagnosis of bearing rolling element with weak response, and is suitable for the fault diagnosis of bearing inner and outer ringsunder strong noise interference.
2022, 41(12): 1829-1838.
doi: 10.13433/j.cnki.1003-8728.20200521
Abstract:
Aiming at the optimization problem of gearbox fault diagnosis, a fault diagnosis method based on parameter optimization of variational mode decomposition (VMD) and convolutional neural network (CNN) is proposed. Firstly, the VMD algorithm is optimized by whale optimization algorithm. Then, the important parameters of CNN model are optimized by orthogonal experiment and particle swarm optimization algorithm. Next, the decomposed natural mode components are input into CNN model for training. After the diagnosis, the training and detection results are obtained. After the algorithm optimization, the training and detection accuracy of CNN model can reach 98.7% and 95.7% respectively, which is better than the non optimization accuracy of 94.3% and 91.8%. Through the analysis of the results, the feasibility of the proposed method and the superiority in the success rate of diagnosis are verified. The adaptive extraction of fault feature information is realized, and the fault types are classified. Finally, the intelligent fault diagnosis on gearboxis realized.
Aiming at the optimization problem of gearbox fault diagnosis, a fault diagnosis method based on parameter optimization of variational mode decomposition (VMD) and convolutional neural network (CNN) is proposed. Firstly, the VMD algorithm is optimized by whale optimization algorithm. Then, the important parameters of CNN model are optimized by orthogonal experiment and particle swarm optimization algorithm. Next, the decomposed natural mode components are input into CNN model for training. After the diagnosis, the training and detection results are obtained. After the algorithm optimization, the training and detection accuracy of CNN model can reach 98.7% and 95.7% respectively, which is better than the non optimization accuracy of 94.3% and 91.8%. Through the analysis of the results, the feasibility of the proposed method and the superiority in the success rate of diagnosis are verified. The adaptive extraction of fault feature information is realized, and the fault types are classified. Finally, the intelligent fault diagnosis on gearboxis realized.
2022, 41(12): 1839-1843.
doi: 10.13433/j.cnki.1003-8728.20200518
Abstract:
A wearable wrist rehabilitation robot was proposed based on the (2-RPS/UPU)&R hybrid mechanism for patients with wrist injury or functional degradation. Three-dimensional modeling was first carried out with SolidWorks and then imported into Adams for forward and inverse kinematics simulation. In the whole simulation process, the performance curves were smooth and there was no mutation point, indicating that the wrist rehabilitation robot had good stability and strong security. The mechanical parameters of muscle in the wrist joint were obtained and the rehabilitation efficacy was evaluated with AnyBody during rehabilitation training. The results showed that the activity and contraction of the muscles around the wrist were consistent with the relevant laws of rehabilitation medicine and would not cause muscle secondary damage, so as to meet the rehabilitation needs of the wrist joint.
A wearable wrist rehabilitation robot was proposed based on the (2-RPS/UPU)&R hybrid mechanism for patients with wrist injury or functional degradation. Three-dimensional modeling was first carried out with SolidWorks and then imported into Adams for forward and inverse kinematics simulation. In the whole simulation process, the performance curves were smooth and there was no mutation point, indicating that the wrist rehabilitation robot had good stability and strong security. The mechanical parameters of muscle in the wrist joint were obtained and the rehabilitation efficacy was evaluated with AnyBody during rehabilitation training. The results showed that the activity and contraction of the muscles around the wrist were consistent with the relevant laws of rehabilitation medicine and would not cause muscle secondary damage, so as to meet the rehabilitation needs of the wrist joint.
2022, 41(12): 1844-1851.
doi: 10.13433/j.cnki.1003-8728.20200548
Abstract:
In order to solve the fatigue failure problem of the hydro-mechanical continuously variable transmission(HMCVT) boxof the heavy tractor due to the complex load in the actual process, a fatigue life prediction method for HMCVT box based on the virtual prototype technology was proposed. A rigid-flexible coupling virtual prototype model for HMCVT box was established based on Adams. Besides, the dynamic excitation of each bearing hole of gearbox shell under different working conditions was acquired. S - N curves of HMCVT boxwere re-fitted under the consideration of load characteristics, structure parameters, and surface technology. Finally, the prediction offatigue life of the HMCVT boxwas conducted based on the Miner linear accumulative damage theory. The results indicated that the S - N curve of the structure has a certaindegreeof modification comparing with the traditional material. The dangerous point of the shell was located at the bore of the idler axle under the dynamic excitation, while the fatigue cumulative damage (D) was 4.8353×10−8, and the life of the HMCVT box is 57447 hours. So, the structure design of the box was conservative and satisfied the requirement of service time.
In order to solve the fatigue failure problem of the hydro-mechanical continuously variable transmission(HMCVT) boxof the heavy tractor due to the complex load in the actual process, a fatigue life prediction method for HMCVT box based on the virtual prototype technology was proposed. A rigid-flexible coupling virtual prototype model for HMCVT box was established based on Adams. Besides, the dynamic excitation of each bearing hole of gearbox shell under different working conditions was acquired. S - N curves of HMCVT boxwere re-fitted under the consideration of load characteristics, structure parameters, and surface technology. Finally, the prediction offatigue life of the HMCVT boxwas conducted based on the Miner linear accumulative damage theory. The results indicated that the S - N curve of the structure has a certaindegreeof modification comparing with the traditional material. The dangerous point of the shell was located at the bore of the idler axle under the dynamic excitation, while the fatigue cumulative damage (D) was 4.8353×10−8, and the life of the HMCVT box is 57447 hours. So, the structure design of the box was conservative and satisfied the requirement of service time.
2022, 41(12): 1852-1859.
doi: 10.13433/j.cnki.1003-8728.20200517
Abstract:
Bionic structure is widely used in various mechanical structures for its excellent mechanical properties. In order to improve the crashworthiness of thin-walled structures, the concept of structural bionics is introduced into the structural design, and a new multi-cell thin-walled energy absorbing structure is proposed. With the increase of biomimetic hierarchical structure, the energy absorption characteristics and deformation mode of bionic thin-walled structure are further improved. At the same time, the response surface method and genetic algorithm are combined to optimize the thin-walled structure with the second-order hierarchical cross-section, and the corresponding Pareto front diagram is obtained, which provides a new idea for the crashworthiness design of the thin-walled tube structure.
Bionic structure is widely used in various mechanical structures for its excellent mechanical properties. In order to improve the crashworthiness of thin-walled structures, the concept of structural bionics is introduced into the structural design, and a new multi-cell thin-walled energy absorbing structure is proposed. With the increase of biomimetic hierarchical structure, the energy absorption characteristics and deformation mode of bionic thin-walled structure are further improved. At the same time, the response surface method and genetic algorithm are combined to optimize the thin-walled structure with the second-order hierarchical cross-section, and the corresponding Pareto front diagram is obtained, which provides a new idea for the crashworthiness design of the thin-walled tube structure.
2022, 41(12): 1860-1868.
doi: 10.13433/j.cnki.1003-8728.20200539
Abstract:
The performance degradation assessment (PDA) is the advance and foundation of gear fault pre-diagnosis. Aiming at the problems that similarity-based methods are of complex models and time consuming, a reconstruction model of gear PDA based on Autoregressive Model (AR) and Dictionary Learning (DL) is proposed. The coefficients of AR model serve as feature vectors to depict gear performance states and DL model is used to reconstruct AR coefficients. Firstly, the over-complete dictionary model are constructed with the AR coefficients of vibration signals under normal operation, and then the AR coefficients of the signals under consideration are input into the DL model as feature vectors to obtain the reconstructed feature vectors. By inputting the signal at hand into the two autoregressive models composed of original AR coefficients and reconstructed AR coefficients respectively, the corresponding residual sequences are obtained. Finally, Mean Squared Error (MSE) is introduced to evaluate the two residual sequences as performance degradation index. Run-to-failure data set from gear are processed to demonstrate the advantages of the method in terms of the trendability, consistency and sensitivity of early failure.
The performance degradation assessment (PDA) is the advance and foundation of gear fault pre-diagnosis. Aiming at the problems that similarity-based methods are of complex models and time consuming, a reconstruction model of gear PDA based on Autoregressive Model (AR) and Dictionary Learning (DL) is proposed. The coefficients of AR model serve as feature vectors to depict gear performance states and DL model is used to reconstruct AR coefficients. Firstly, the over-complete dictionary model are constructed with the AR coefficients of vibration signals under normal operation, and then the AR coefficients of the signals under consideration are input into the DL model as feature vectors to obtain the reconstructed feature vectors. By inputting the signal at hand into the two autoregressive models composed of original AR coefficients and reconstructed AR coefficients respectively, the corresponding residual sequences are obtained. Finally, Mean Squared Error (MSE) is introduced to evaluate the two residual sequences as performance degradation index. Run-to-failure data set from gear are processed to demonstrate the advantages of the method in terms of the trendability, consistency and sensitivity of early failure.
2022, 41(12): 1869-1876.
doi: 10.13433/j.cnki.1003-8728.20200532
Abstract:
In this paper, an active disturbance rejection trajectory trackingcontroller for a 4-Mecanum wheel omnidirectional mobile robot is presented. Firstly, the kinematic and dynamic model of the robot is analyzed. Secondly, the kinematic controller is designed with the backstepping method. An improved extended state observer and dynamic controller is designed because the disturbances during the robot′s movement remain unknown. Finally, simulation is carried out under the influence of different disturbances. The comparison results show that the controller has smaller tracking error and faster convergence speed. The extended state observer estimates the disturbances quickly and accurately with uncertain factors as well as making real-time compensation, thus verifying that the controller has better anti-interference and robustness.
In this paper, an active disturbance rejection trajectory trackingcontroller for a 4-Mecanum wheel omnidirectional mobile robot is presented. Firstly, the kinematic and dynamic model of the robot is analyzed. Secondly, the kinematic controller is designed with the backstepping method. An improved extended state observer and dynamic controller is designed because the disturbances during the robot′s movement remain unknown. Finally, simulation is carried out under the influence of different disturbances. The comparison results show that the controller has smaller tracking error and faster convergence speed. The extended state observer estimates the disturbances quickly and accurately with uncertain factors as well as making real-time compensation, thus verifying that the controller has better anti-interference and robustness.
2022, 41(12): 1877-1886.
doi: 10.13433/j.cnki.1003-8728.20220299
Abstract:
To reduce the failure rate of the metal-rubber shock absorber and reduce the economic loss caused by the damage of the metal-rubber shock absorber, by analyzing the failure causes of the metal-rubber shock absorber, and establishing models for simulation analysis and theoretical analysis of the metal-rubber shock absorber, the optimization design method of the metal-rubber shock absorber under large loads is proposed. The mathematical model of the metal-rubber shock absorber is first established. The overall optimization of the metal-rubber shock absorber is carried out using the genetic algorithm. The optimization result is determined by combining with the finite element analysis, the experimental verification is finally carried out. The results show that the stiffness of the optimized metal-rubber shock absorber is significantly enhanced, and the compressive capacity of the metal-rubber shock absorber is also improved to a certain extent. There is a certain error between the simulation results and the experimental results, but the optimized metal-rubber shock absorber meets the working requirements of the carrier vehicle, so the optimization design of the shock absorber has achieved the expected goal.
To reduce the failure rate of the metal-rubber shock absorber and reduce the economic loss caused by the damage of the metal-rubber shock absorber, by analyzing the failure causes of the metal-rubber shock absorber, and establishing models for simulation analysis and theoretical analysis of the metal-rubber shock absorber, the optimization design method of the metal-rubber shock absorber under large loads is proposed. The mathematical model of the metal-rubber shock absorber is first established. The overall optimization of the metal-rubber shock absorber is carried out using the genetic algorithm. The optimization result is determined by combining with the finite element analysis, the experimental verification is finally carried out. The results show that the stiffness of the optimized metal-rubber shock absorber is significantly enhanced, and the compressive capacity of the metal-rubber shock absorber is also improved to a certain extent. There is a certain error between the simulation results and the experimental results, but the optimized metal-rubber shock absorber meets the working requirements of the carrier vehicle, so the optimization design of the shock absorber has achieved the expected goal.
2022, 41(12): 1887-1893.
doi: 10.13433/j.cnki.1003-8728.20220313
Abstract:
In order to study the influence of the different factors on the energy harvesting efficiency of piezoelectric ceramics and improve the energy harvesting efficiency, lead zirconate titanate piezoelectric ceramics are studied in this paper. First of all, an experimental test platform is built, and the relationship between PZT output voltage and excitation frequency under three different vibration amplitudes (2, 6, 10 mm) is obtained, and the optimal energy harvesting parameters of the tested PZT sample are obtained. Secondly, based on the optimization of the memory circuit, the PZT is connected to the memory circuit in the modes of single-sheet, double-sheet series, double-sheet parallel connection and double input, respectively, and every mode PZT has continuously vibrated for 30 min under the optimal energy harvesting parameters to charge the lithium battery in the storage circuit. Finally, the energy harvesting efficiency of differentinput modes is evaluated by comparing the duration of diodes driven by lithium batteries. The results show that the parallel mode has the highest energy harvesting efficiency after vibrating with the optimal energy harvesting parameters for 30 min, which can make the diode (60 mW) work continuously for 120 s.
In order to study the influence of the different factors on the energy harvesting efficiency of piezoelectric ceramics and improve the energy harvesting efficiency, lead zirconate titanate piezoelectric ceramics are studied in this paper. First of all, an experimental test platform is built, and the relationship between PZT output voltage and excitation frequency under three different vibration amplitudes (2, 6, 10 mm) is obtained, and the optimal energy harvesting parameters of the tested PZT sample are obtained. Secondly, based on the optimization of the memory circuit, the PZT is connected to the memory circuit in the modes of single-sheet, double-sheet series, double-sheet parallel connection and double input, respectively, and every mode PZT has continuously vibrated for 30 min under the optimal energy harvesting parameters to charge the lithium battery in the storage circuit. Finally, the energy harvesting efficiency of differentinput modes is evaluated by comparing the duration of diodes driven by lithium batteries. The results show that the parallel mode has the highest energy harvesting efficiency after vibrating with the optimal energy harvesting parameters for 30 min, which can make the diode (60 mW) work continuously for 120 s.
2022, 41(12): 1894-1899.
doi: 10.13433/j.cnki.1003-8728.20200533
Abstract:
In In order to verify the reliability of the dust removal system in the laser die-cutting station of lithium-ion battery, the movement process of jet particles in the laser die-cutting station cavity was taken as the research object, and the movement process of dust particles in the cavity was simulated.The working principle of air curtain blocking dust removal by air knife jet was proposed. Meanwhile, the simulation of the whole process of air knife blocking dust removal was carried out so as to obtain the movement track law of dust particles.According to the statistics, the proportion of the final destination of dust particles in the exit cavity was followed by system dust removal (61.07%) > attached wall surface (21.25%) and > attached pole plate (10.01%) and > escape (7.69%).
In In order to verify the reliability of the dust removal system in the laser die-cutting station of lithium-ion battery, the movement process of jet particles in the laser die-cutting station cavity was taken as the research object, and the movement process of dust particles in the cavity was simulated.The working principle of air curtain blocking dust removal by air knife jet was proposed. Meanwhile, the simulation of the whole process of air knife blocking dust removal was carried out so as to obtain the movement track law of dust particles.According to the statistics, the proportion of the final destination of dust particles in the exit cavity was followed by system dust removal (61.07%) > attached wall surface (21.25%) and > attached pole plate (10.01%) and > escape (7.69%).
2022, 41(12): 1900-1906.
doi: 10.13433/j.cnki.1003-8728.20200550
Abstract:
In this study, the influence of passive prechamber jet ignition mode and spark plug ignition mode (SI) on combustion performance was compared and analyzed by tests. The results showed that: SI engine was limited by detonation under high load, it achieved the best fuel consumption rate and thermal efficiency only under medium load. The fuel consumption and thermal efficiency were promoted with increase of compression ratio (CR) under small and medium loads. Compared with SI mode, passive prechamberjet ignition mode can achieve faster burning velocity and flame propagation speed, so it had good inhibition effect of SI detonation, resulting in lower fuel consumption ratio and higher thermal efficiency under medium load. But the fuel consumption rate and thermal efficiency of passive prechamber jet ignition deteriorated under low and high load. Incylinder combustion rate can be effectively increased when using passive prechamberjet ignition, so the bad effect of CA50 delay on fuel consumption can be weakened, especially the potential and effect of increasing the compression ratio to reduce fuel consumption were better when using passive prechamberjet ignition mode.
In this study, the influence of passive prechamber jet ignition mode and spark plug ignition mode (SI) on combustion performance was compared and analyzed by tests. The results showed that: SI engine was limited by detonation under high load, it achieved the best fuel consumption rate and thermal efficiency only under medium load. The fuel consumption and thermal efficiency were promoted with increase of compression ratio (CR) under small and medium loads. Compared with SI mode, passive prechamberjet ignition mode can achieve faster burning velocity and flame propagation speed, so it had good inhibition effect of SI detonation, resulting in lower fuel consumption ratio and higher thermal efficiency under medium load. But the fuel consumption rate and thermal efficiency of passive prechamber jet ignition deteriorated under low and high load. Incylinder combustion rate can be effectively increased when using passive prechamberjet ignition, so the bad effect of CA50 delay on fuel consumption can be weakened, especially the potential and effect of increasing the compression ratio to reduce fuel consumption were better when using passive prechamberjet ignition mode.
2022, 41(12): 1907-1913.
doi: 10.13433/j.cnki.1003-8728.20200546
Abstract:
In order to explore the influence of the different laser impact areas on the fatigue performance of aluminum alloy plate notched, the effect of the laser impact treatment on the different areas of 7075-T651 alloy plate structure notchedis conducted. The first method is laser impact only on the edge of the gap, and the second method is laser impact within a certain range of the gap. The results show that the surface roughness of the plate is smaller and the characteristic fatigue life of the plate is 3.23 times than that of the second laser impact method. Through the finite element simulation analysis of the plate subjected the laser impact, the reason of the laser impact on the fatigue life of the plate was revealed. Only to set the reasonable laser impact parameters and impact area will effectively improve the fatigue performance and the fatigue life of the structure be will increase, while the unreasonable impact treatment will reduce the fatigue life of the structure.
In order to explore the influence of the different laser impact areas on the fatigue performance of aluminum alloy plate notched, the effect of the laser impact treatment on the different areas of 7075-T651 alloy plate structure notchedis conducted. The first method is laser impact only on the edge of the gap, and the second method is laser impact within a certain range of the gap. The results show that the surface roughness of the plate is smaller and the characteristic fatigue life of the plate is 3.23 times than that of the second laser impact method. Through the finite element simulation analysis of the plate subjected the laser impact, the reason of the laser impact on the fatigue life of the plate was revealed. Only to set the reasonable laser impact parameters and impact area will effectively improve the fatigue performance and the fatigue life of the structure be will increase, while the unreasonable impact treatment will reduce the fatigue life of the structure.
2022, 41(12): 1914-1920.
doi: 10.13433/j.cnki.1003-8728.20200540
Abstract:
The processing parameters of H13 steel formed with laser-powder bed fusion were optimized through experimental methods, and the microstructure and tensile properties of the formed samples were studied. The optimal processing interval of H13 steel single track forming is obtained through experiments: laser power 225～325 W, scaning speed 600～1200 mm/s. The optimal processing parameters obtained through the block experiment are: laser power 275 W, scanning speed 900 mm/s, hatch space 0.08 mm. The microstructure shows columnar grains with a width of about 3～5 μm and a length of about 10～40 μm. Under the optimal processing parameters, the tensile strength at room temperature is as high as 1 761 MPa and the elongation is 2.72%.
The processing parameters of H13 steel formed with laser-powder bed fusion were optimized through experimental methods, and the microstructure and tensile properties of the formed samples were studied. The optimal processing interval of H13 steel single track forming is obtained through experiments: laser power 225～325 W, scaning speed 600～1200 mm/s. The optimal processing parameters obtained through the block experiment are: laser power 275 W, scanning speed 900 mm/s, hatch space 0.08 mm. The microstructure shows columnar grains with a width of about 3～5 μm and a length of about 10～40 μm. Under the optimal processing parameters, the tensile strength at room temperature is as high as 1 761 MPa and the elongation is 2.72%.
2022, 41(12): 1921-1927.
doi: 10.13433/j.cnki.1003-8728.20200511
Abstract:
Titanium alloy blisk is an important part in the aero-engine, which has complex structure and difficult machining. Plunge milling is very suitable for machining difficult-to-cut materials such as titanium alloys and complex components due to its strong axial bearing capacity and high rigidity. Aiming at the machining efficiency in plunge milling of titanium alloy, the plunge milling experiment is designed by using the response surface methodology, and an empirical model for cutting force is established. With the goal of cutting force and material removal rate, the NSGA-II is used for multi-objective optimization to obtain the Pareto optimal solution. The results show that the cutting force decreases slowly with the increasing of spindle speed, and increases with the increasing of cutting width, cutting step and feed per tooth. Comparing with the experimental initial parameter combination, the optimal material removal rate increased by 81.19%, and the cutting force reduced by 23.68%. The results show that the present method can achieve the goal of high efficiency machining.
Titanium alloy blisk is an important part in the aero-engine, which has complex structure and difficult machining. Plunge milling is very suitable for machining difficult-to-cut materials such as titanium alloys and complex components due to its strong axial bearing capacity and high rigidity. Aiming at the machining efficiency in plunge milling of titanium alloy, the plunge milling experiment is designed by using the response surface methodology, and an empirical model for cutting force is established. With the goal of cutting force and material removal rate, the NSGA-II is used for multi-objective optimization to obtain the Pareto optimal solution. The results show that the cutting force decreases slowly with the increasing of spindle speed, and increases with the increasing of cutting width, cutting step and feed per tooth. Comparing with the experimental initial parameter combination, the optimal material removal rate increased by 81.19%, and the cutting force reduced by 23.68%. The results show that the present method can achieve the goal of high efficiency machining.
2022, 41(12): 1928-1935.
doi: 10.13433/j.cnki.1003-8728.20200534
Abstract:
At present, high dust, low illumination and other factors affect the accuracy of position measurementseriously. To calibratethe external parameters of the position detection system of thecantilever roadheadersuch as parallel laser line, an external parameter calibration method based on the digital total station is proposed. The influence of external parameter calibration error on position measurement is analyzed in detail. By establishing the coordinate conversion relationship between modules in the visual position measurement system, the calibration principle of the external parameters of the position detectionsystem is modeled mathematically. The position of the fuselage relative to the road according to the calibration results on the external parameters of thedigital total station is obtained with the position detection method for the digitaltotal station. The experimental results show that the position measurement error of the external reference calibration method of the cantilever roadheader is within ±3 mm and that the attitude angle measurement error is within 0.08°. The accuracy results are obtained with the external reference calibration method. The average positionerrorsin x, y and z directions increase by 13.073 mm, 21.511mm and 18.159°, respectively.
At present, high dust, low illumination and other factors affect the accuracy of position measurementseriously. To calibratethe external parameters of the position detection system of thecantilever roadheadersuch as parallel laser line, an external parameter calibration method based on the digital total station is proposed. The influence of external parameter calibration error on position measurement is analyzed in detail. By establishing the coordinate conversion relationship between modules in the visual position measurement system, the calibration principle of the external parameters of the position detectionsystem is modeled mathematically. The position of the fuselage relative to the road according to the calibration results on the external parameters of thedigital total station is obtained with the position detection method for the digitaltotal station. The experimental results show that the position measurement error of the external reference calibration method of the cantilever roadheader is within ±3 mm and that the attitude angle measurement error is within 0.08°. The accuracy results are obtained with the external reference calibration method. The average positionerrorsin x, y and z directions increase by 13.073 mm, 21.511mm and 18.159°, respectively.
2022, 41(12): 1936-1942.
doi: 10.13433/j.cnki.1003-8728.20220314
Abstract:
In the power system, different manufacturers have different field equipment interfaces, which forms information islands and makes it difficult to integrate field equipment in practice. According to the current data acquisition technology that Modbus RTU and various PLC protocols commonly used in power equipment, the OPC UA conversion unit of the existing interface protocol is designed based on the requirements of power equipment operation status monitoring, the embedded minimum system hardware platform for OPC UA protocol conversion of heterogeneous power equipment is developed, and a unified output interface based on OPC UA protocol standardization is established. The hardware platform uses software configuration to realize unified access of on-site data collection intelligent devices, which can efficiently support heterogeneous standardized cross platform operation with OPC UA protocol as output, and is conducive to support the realization of cloud side collaborative parameter collection of more different kinds of collection terminals at the same time.
In the power system, different manufacturers have different field equipment interfaces, which forms information islands and makes it difficult to integrate field equipment in practice. According to the current data acquisition technology that Modbus RTU and various PLC protocols commonly used in power equipment, the OPC UA conversion unit of the existing interface protocol is designed based on the requirements of power equipment operation status monitoring, the embedded minimum system hardware platform for OPC UA protocol conversion of heterogeneous power equipment is developed, and a unified output interface based on OPC UA protocol standardization is established. The hardware platform uses software configuration to realize unified access of on-site data collection intelligent devices, which can efficiently support heterogeneous standardized cross platform operation with OPC UA protocol as output, and is conducive to support the realization of cloud side collaborative parameter collection of more different kinds of collection terminals at the same time.
2022, 41(12): 1943-1949.
doi: 10.13433/j.cnki.1003-8728.20200535
Abstract:
The paper takes the vibration signal feature extraction and modeling analysis under strong background noise as the research objective, and proposes a signal transformation method to convert the vibration signal into a vibration image. The experimental data setincludes the vibration signal for deep groove ball bearing fault diagnosis and the vibration signal for bearing quality evaluation,based onconvolutional neural network model (VI-CNN) of vibration images, and the correct recognition rate (CRR) is used as an evaluation index of model accuracy. The experimental results show that for the qualitative discrimination of bearing fault diagnosis and quality level evaluation, the correct recognition rates of VI-CNNmodel compared with other modeling methods are 100% and 98.16%, indicating the model has better robustness.
The paper takes the vibration signal feature extraction and modeling analysis under strong background noise as the research objective, and proposes a signal transformation method to convert the vibration signal into a vibration image. The experimental data setincludes the vibration signal for deep groove ball bearing fault diagnosis and the vibration signal for bearing quality evaluation,based onconvolutional neural network model (VI-CNN) of vibration images, and the correct recognition rate (CRR) is used as an evaluation index of model accuracy. The experimental results show that for the qualitative discrimination of bearing fault diagnosis and quality level evaluation, the correct recognition rates of VI-CNNmodel compared with other modeling methods are 100% and 98.16%, indicating the model has better robustness.
2022, 41(12): 1950-1957.
doi: 10.13433/j.cnki.1003-8728.20220311
Abstract:
In order to study the influence of the different factors on the wear resistance of the orifice valve sliding valve self-locking device, rolling-sliding friction tests under orthogonal conditions were carried out. Different ball/disc friction pairs materials, disc roughness, and lubrication medium were selected as the influencing factors. The results show that the optimized parameters of sensitivity analysis are: disc material 440C, ball material 440C, disc roughness Ra = 0.4 μm, and grease lubrication conditions. The optimized parameters pairs run well after test, and the surface morphology of the ball/disc has slight wear. It shows that the anti-wear performance of the optimal parameters meets the service life requirements.
In order to study the influence of the different factors on the wear resistance of the orifice valve sliding valve self-locking device, rolling-sliding friction tests under orthogonal conditions were carried out. Different ball/disc friction pairs materials, disc roughness, and lubrication medium were selected as the influencing factors. The results show that the optimized parameters of sensitivity analysis are: disc material 440C, ball material 440C, disc roughness Ra = 0.4 μm, and grease lubrication conditions. The optimized parameters pairs run well after test, and the surface morphology of the ball/disc has slight wear. It shows that the anti-wear performance of the optimal parameters meets the service life requirements.
2022, 41(12): 1958-1964.
doi: 10.13433/j.cnki.1003-8728.20200529
Abstract:
Based on the classical beam theory (CBT), the transverse free vibration and critical buckling load of fiber reinforced functionally graded material (FGM) beams subjected to axial force are studied. Firstly, the mixing law model is considered to characterize the material properties of the fiber reinforced FGM beam. Secondly, the governing differential equations of transverse free vibration and critical buckling load of the fiber reinforced FGM beam subjected to axial force are derived by Hamilton principle, and the governing differential equations and boundary conditions are transformed by differential transformation method (DTM). The dimensional natural frequencies for transverse free vibration and dimensionless critical buckling loads of the fiber reinforced FGM beam are calculated under three boundary conditions of clamped-clamped (C-C), clamped-simply supported (C-S) and simply supported-simply supported (S-S). The problem is reduced to homogeneous material beams and FGM beams and compared with the existing literatures to verify its effectiveness. Finally, the effects of stiffness ratio, fiber volume fraction and dimensionless compressive load on the dimensionless natural frequency and all parameters on the dimensionless critical buckling load of the fiber reinforced FGM beam under different boundary conditions are discussed.
Based on the classical beam theory (CBT), the transverse free vibration and critical buckling load of fiber reinforced functionally graded material (FGM) beams subjected to axial force are studied. Firstly, the mixing law model is considered to characterize the material properties of the fiber reinforced FGM beam. Secondly, the governing differential equations of transverse free vibration and critical buckling load of the fiber reinforced FGM beam subjected to axial force are derived by Hamilton principle, and the governing differential equations and boundary conditions are transformed by differential transformation method (DTM). The dimensional natural frequencies for transverse free vibration and dimensionless critical buckling loads of the fiber reinforced FGM beam are calculated under three boundary conditions of clamped-clamped (C-C), clamped-simply supported (C-S) and simply supported-simply supported (S-S). The problem is reduced to homogeneous material beams and FGM beams and compared with the existing literatures to verify its effectiveness. Finally, the effects of stiffness ratio, fiber volume fraction and dimensionless compressive load on the dimensionless natural frequency and all parameters on the dimensionless critical buckling load of the fiber reinforced FGM beam under different boundary conditions are discussed.
2022, 41(12): 1965-1972.
doi: 10.13433/j.cnki.1003-8728.20200538
Abstract:
In order to solve the problem that it is difficult to determine the critical failure mode of aeroengine spindle bearing,a method of failure mode importance evaluation for aeroengine spindle bearing based on rough cloud model and preference ranking organization method for enrichment evaluation (PROMETHEE) is proposed in this study. Combined with the failure mode and effects analysis (FMEA) method, the risk assessment matrix of each failure mode of spindle bearing was first constructed by expert system.Using rough set theory and cloud model theory, the risk assessment matrix was then transformed into rough cloud assessment matrix to describe the subjectivity, fuzziness and randomness of expert assessment information.After using PROMETHEE to calculate the leaving, entering and net flow of each failure mode, the six failure modes of aeroenginespindle bearing were ranked according to the net flow, providing a reliable basis for formulating preventive measures and reducing risks.
In order to solve the problem that it is difficult to determine the critical failure mode of aeroengine spindle bearing,a method of failure mode importance evaluation for aeroengine spindle bearing based on rough cloud model and preference ranking organization method for enrichment evaluation (PROMETHEE) is proposed in this study. Combined with the failure mode and effects analysis (FMEA) method, the risk assessment matrix of each failure mode of spindle bearing was first constructed by expert system.Using rough set theory and cloud model theory, the risk assessment matrix was then transformed into rough cloud assessment matrix to describe the subjectivity, fuzziness and randomness of expert assessment information.After using PROMETHEE to calculate the leaving, entering and net flow of each failure mode, the six failure modes of aeroenginespindle bearing were ranked according to the net flow, providing a reliable basis for formulating preventive measures and reducing risks.
