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RSS2021 Vol. 40, No. 10
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2021, 40(10): 1477-1483.
doi: 10.13433/j.cnki.1003-8728.20200244
PDF 1947KB
Abstract:
Based on the study of auto-tensioner and Combining the nonlinear finite element analysis of the EFEAD (Engine front end accessory drive) system, a comprehensive objective function was defined by the compromise programming approach, which maximized the static, steady-state stiffness and dynamic vibration frequency. An improved combination weighting radar chart method was applied to obtain the optimal weights of various loading conditions in order to conduct multi-objective optimization design of a tensioner arm. Moreover, the contrastive study was carried out to compare the results on the radar chart methods that determine the weight ratio with empirical design, equipartition law and analytic hierarchy process. The comparison results indicate that the radar chart method is superior to other reference methods. Finally, the tensioner arm was optimized, and the analytic results show that as the mass of the optimized structure is reduced, the stiffness and strength performances are enhanced and that the natural frequency of the model of each order meets the requirement.
Based on the study of auto-tensioner and Combining the nonlinear finite element analysis of the EFEAD (Engine front end accessory drive) system, a comprehensive objective function was defined by the compromise programming approach, which maximized the static, steady-state stiffness and dynamic vibration frequency. An improved combination weighting radar chart method was applied to obtain the optimal weights of various loading conditions in order to conduct multi-objective optimization design of a tensioner arm. Moreover, the contrastive study was carried out to compare the results on the radar chart methods that determine the weight ratio with empirical design, equipartition law and analytic hierarchy process. The comparison results indicate that the radar chart method is superior to other reference methods. Finally, the tensioner arm was optimized, and the analytic results show that as the mass of the optimized structure is reduced, the stiffness and strength performances are enhanced and that the natural frequency of the model of each order meets the requirement.
2021, 40(10): 1484-1490.
doi: 10.13433/j.cnki.1003-8728.20200239
Abstract:
To solve the problem of artificial determination of variational modal decomposition parameters and to achieve accurate diagnosis of bearing faults, a new bearing fault diagnosis method based on the variational modal decomposition (VMD) which is optimized with information entropy and ensemble kurtosis, and particle swarm optimized support vector machine(PSO-SVM) is constructed in this study. In this method, optimize the VMD parameters by using the principle of minimum of product of the reciprocal of ensemble kurtosis and the information entropy; decompose the original fault signal by the above optimized VMD and obtain some established intrinsic mode functions (IMFs); select the IMF with the minimum product of the information entropy and the reciprocal of ensemble kurtosis as the best IMF, and extract its fault features to form the feature vector and input PSO-SVM to classify the fault type. Both simulation signal and the actual bearing data are applied to verify the effectiveness of proposed method.
To solve the problem of artificial determination of variational modal decomposition parameters and to achieve accurate diagnosis of bearing faults, a new bearing fault diagnosis method based on the variational modal decomposition (VMD) which is optimized with information entropy and ensemble kurtosis, and particle swarm optimized support vector machine(PSO-SVM) is constructed in this study. In this method, optimize the VMD parameters by using the principle of minimum of product of the reciprocal of ensemble kurtosis and the information entropy; decompose the original fault signal by the above optimized VMD and obtain some established intrinsic mode functions (IMFs); select the IMF with the minimum product of the information entropy and the reciprocal of ensemble kurtosis as the best IMF, and extract its fault features to form the feature vector and input PSO-SVM to classify the fault type. Both simulation signal and the actual bearing data are applied to verify the effectiveness of proposed method.
2021, 40(10): 1491-1496.
doi: 10.13433/j.cnki.1003-8728.20200234
Abstract:
This paper uses the Sobol method of variance decomposition to calculate the sensitivities of model parameters, spring stiffness, damping factor and mass on the force bandwidth and impedance of series elastic actuator (SEA), and analyzes their convergences in different sample size to look for the reliable result with minimum calculation cost. And the research results indicate that the sensitivity of damping factor and mass are greater than that of spring stiffness in most frequencies, specifically, the total sensitivities of damping factor and mass is about 3 or 4 times greater than that of spring stiffness, though the sensitivities of spring stiffness, damping factor and mass have interactive influence on the force bandwidth and impedance and vary with the frequency; and the results of the convergences analysis show that the amplitude of Sobol index below 5 000 size of sample is larger than that above 5 000, therefore a believable result with minimum calculation cost could be obtained when the sample size is 5 000.
This paper uses the Sobol method of variance decomposition to calculate the sensitivities of model parameters, spring stiffness, damping factor and mass on the force bandwidth and impedance of series elastic actuator (SEA), and analyzes their convergences in different sample size to look for the reliable result with minimum calculation cost. And the research results indicate that the sensitivity of damping factor and mass are greater than that of spring stiffness in most frequencies, specifically, the total sensitivities of damping factor and mass is about 3 or 4 times greater than that of spring stiffness, though the sensitivities of spring stiffness, damping factor and mass have interactive influence on the force bandwidth and impedance and vary with the frequency; and the results of the convergences analysis show that the amplitude of Sobol index below 5 000 size of sample is larger than that above 5 000, therefore a believable result with minimum calculation cost could be obtained when the sample size is 5 000.
2021, 40(10): 1497-1502.
doi: 10.13433/j.cnki.1003-8728.20200242
Abstract:
In order to make the globoidal CAM in the process of high-speed rotation have the advantages of small vibration, small wear, high precision and efficiency, based on the superior performances of NURBS, the contour curves of the existing spatial globoidal indexing CAM are designed. The order is selected according to different starting and stopping boundary conditions, and the NURBS flexible CAM curves under various motion control conditions are obtained. Multi-objective optimization was performed with the standard 5-times and dual-stay NURBS CAM curve. Based on the function of the NX "regular curve", a new modeling method is adopted to establish a three-dimensional model of cambered CAM. The contour curve constructed by this method is accurate and efficient. Then MATLAB is used to compare the NURBS flexible CAM curve with the MS curve. The ADAMS dynamics simulation is used to simulate the motion of the CAM mechanism. The simulation results show that the motion performance of the 5-NURBS CAM curve is better than the MS curve. The cambered CAM made with this method has the advantages of stable vibration, small wear and good performance.
In order to make the globoidal CAM in the process of high-speed rotation have the advantages of small vibration, small wear, high precision and efficiency, based on the superior performances of NURBS, the contour curves of the existing spatial globoidal indexing CAM are designed. The order is selected according to different starting and stopping boundary conditions, and the NURBS flexible CAM curves under various motion control conditions are obtained. Multi-objective optimization was performed with the standard 5-times and dual-stay NURBS CAM curve. Based on the function of the NX "regular curve", a new modeling method is adopted to establish a three-dimensional model of cambered CAM. The contour curve constructed by this method is accurate and efficient. Then MATLAB is used to compare the NURBS flexible CAM curve with the MS curve. The ADAMS dynamics simulation is used to simulate the motion of the CAM mechanism. The simulation results show that the motion performance of the 5-NURBS CAM curve is better than the MS curve. The cambered CAM made with this method has the advantages of stable vibration, small wear and good performance.
2021, 40(10): 1503-1507.
doi: 10.13433/j.cnki.1003-8728.20200236
Abstract:
The life and damage of the wheel bearing are one of the important factors that directly affect the life and safety of the car. In this paper, we predict the rotating bending fatigue life of the third generation hub bearing. First, ABAQUS is used to perform dynamic finite element simulation of the hub bearing. Secondly, nCode life software is used to analyze and obtain the model life cloud to predict the fatigue life. Then we use a rotating bending fatigue testing machine to test and analyze the test data to verify the feasibility of the rotating bending fatigue life prediction model. Finally, the reliability analysis of the test results is carried out, and the reliability of the prediction results is evaluated by the reliability function graph.
The life and damage of the wheel bearing are one of the important factors that directly affect the life and safety of the car. In this paper, we predict the rotating bending fatigue life of the third generation hub bearing. First, ABAQUS is used to perform dynamic finite element simulation of the hub bearing. Secondly, nCode life software is used to analyze and obtain the model life cloud to predict the fatigue life. Then we use a rotating bending fatigue testing machine to test and analyze the test data to verify the feasibility of the rotating bending fatigue life prediction model. Finally, the reliability analysis of the test results is carried out, and the reliability of the prediction results is evaluated by the reliability function graph.
2021, 40(10): 1508-1514.
doi: 10.13433/j.cnki.1003-8728.20200210
Abstract:
Because the wire core of a current distribution robot is easily damaged during its stripping process, we proposed the cutting force tracking control algorithm based on the impedance control suitable for an end stripper. At present, the task requirements for sudden changes in environment stiffness cannot be met through many types of impedance control because of the distribution robot′s complexity of working environment stiffness, the recursive least squares (RLS) method was introduced into the impedance control algorithm to identify the wire insulation and core stiffness online to achieve the accurate and stable tracking of the cutting force. Furthermore, the impedance control of the stripping process of the distribution robot and the RLS method were simulated and tested contrastively in MATLAB/Simulink. The contrastive simulation results show that the impedance control algorithm based on the parameter identification with the RLS method still has a good force tracking performance during sudden changes in environment stiffness and that the steady-state error approaches zero, showing that the impedance control algorithm is feasible and effective.
Because the wire core of a current distribution robot is easily damaged during its stripping process, we proposed the cutting force tracking control algorithm based on the impedance control suitable for an end stripper. At present, the task requirements for sudden changes in environment stiffness cannot be met through many types of impedance control because of the distribution robot′s complexity of working environment stiffness, the recursive least squares (RLS) method was introduced into the impedance control algorithm to identify the wire insulation and core stiffness online to achieve the accurate and stable tracking of the cutting force. Furthermore, the impedance control of the stripping process of the distribution robot and the RLS method were simulated and tested contrastively in MATLAB/Simulink. The contrastive simulation results show that the impedance control algorithm based on the parameter identification with the RLS method still has a good force tracking performance during sudden changes in environment stiffness and that the steady-state error approaches zero, showing that the impedance control algorithm is feasible and effective.
2021, 40(10): 1515-1522.
doi: 10.13433/j.cnki.1003-8728.20200251
Abstract:
The valve shaft is the key force component of butterfly valve, the traditional calculation method of the valve shaft stress is based on the torque which not fully considers the bending moment effect, so there exist the certain risks for applying to the large butterfly valves design. In this paper, the sliding bearing constraint force is simplified to uniform distributed-load or concentrated force, by combining with the compatibility equation, then a new model for valve shaft bending and torsion combination is proposed, thus finite element and experimental method is used to verify the present model. Finally, the valve shaft stress is evaluated with the Von Mises stress and Goodman criteria respectively, and the safety factor of the valve shaft design is obtained. The results show that the given model and evaluation method of the butterfly valve shaft calculation perform with high precision, which are of the important guiding significance to improve the design method of butterfly valve.
The valve shaft is the key force component of butterfly valve, the traditional calculation method of the valve shaft stress is based on the torque which not fully considers the bending moment effect, so there exist the certain risks for applying to the large butterfly valves design. In this paper, the sliding bearing constraint force is simplified to uniform distributed-load or concentrated force, by combining with the compatibility equation, then a new model for valve shaft bending and torsion combination is proposed, thus finite element and experimental method is used to verify the present model. Finally, the valve shaft stress is evaluated with the Von Mises stress and Goodman criteria respectively, and the safety factor of the valve shaft design is obtained. The results show that the given model and evaluation method of the butterfly valve shaft calculation perform with high precision, which are of the important guiding significance to improve the design method of butterfly valve.
2021, 40(10): 1523-1529.
doi: 10.13433/j.cnki.1003-8728.20200252
Abstract:
When using the Multi-scale Permutation Entropy (MPE), with the increase of the scale factor, the obtained coarse-grained time series becomes shorter and shorter, which results in serious loss of time series information. For this purpose, a new Time-shifted Multi-scale Permutation Entropy (TSMPE) is put forward in this study. Firstly, the comparison of TSMPE and MPE is carried out with simulated signal. The results show that TSMPE has less dependence on signal length and the obtained entropy value is more stable. Furthermore, based on TSMPE and extreme learning machine, a fault detection and diagnosis method for rolling bearing is proposed and applied to two testing data of actual rolling bearings to identify the fault types and degrees. The results show that the proposed fault diagnosis method can not only accurately diagnose the fault types and degrees of rolling bearings, but also the recognition rates are higher than the fault diagnosis methods based on MPE and ELM.
When using the Multi-scale Permutation Entropy (MPE), with the increase of the scale factor, the obtained coarse-grained time series becomes shorter and shorter, which results in serious loss of time series information. For this purpose, a new Time-shifted Multi-scale Permutation Entropy (TSMPE) is put forward in this study. Firstly, the comparison of TSMPE and MPE is carried out with simulated signal. The results show that TSMPE has less dependence on signal length and the obtained entropy value is more stable. Furthermore, based on TSMPE and extreme learning machine, a fault detection and diagnosis method for rolling bearing is proposed and applied to two testing data of actual rolling bearings to identify the fault types and degrees. The results show that the proposed fault diagnosis method can not only accurately diagnose the fault types and degrees of rolling bearings, but also the recognition rates are higher than the fault diagnosis methods based on MPE and ELM.
2021, 40(10): 1530-1535.
doi: 10.13433/j.cnki.1003-8728.20200233
Abstract:
Aiming at the problem that it is difficult to extract vibration signal features of train wheel damage, a new diagnosis method of the wheel damage based on variational mode decomposition (VMD) improved multiscale permutation entropy and linear local tangent space alignment (LLTSA) is proposed in this paper. Firstly, the original vibration signal of train wheel with damage is decomposed into some modal components by VMD. The improved multiscale permutation entropy of each modal component is calculated. Then, the feature dimension is reduced using LLTSA and compared with the dimensionality reduction results of isometric mapping (ISOMAP), and the optimal low-dimensional feature vector is obtained. Finally, the feature vector is input into the kernel extreme learning machine (KELM) for classification and recognition. The experimental analysis results show that this method can identify wheel damage states successfully.
Aiming at the problem that it is difficult to extract vibration signal features of train wheel damage, a new diagnosis method of the wheel damage based on variational mode decomposition (VMD) improved multiscale permutation entropy and linear local tangent space alignment (LLTSA) is proposed in this paper. Firstly, the original vibration signal of train wheel with damage is decomposed into some modal components by VMD. The improved multiscale permutation entropy of each modal component is calculated. Then, the feature dimension is reduced using LLTSA and compared with the dimensionality reduction results of isometric mapping (ISOMAP), and the optimal low-dimensional feature vector is obtained. Finally, the feature vector is input into the kernel extreme learning machine (KELM) for classification and recognition. The experimental analysis results show that this method can identify wheel damage states successfully.
2021, 40(10): 1536-1540.
doi: 10.13433/j.cnki.1003-8728.20200246
Abstract:
The on-machine detection technique can realize the real-time monitoring of a tool in working state, which is of the significance to identify quality issues of the tool in time and improves the detection efficiency. Based on the machine vision techniques, a fast steering mirror was used to assist industrial camera in capturing clear tool images, and an image acquisition system was established in this paper. A control program was developed by investigating the deflection model for the fast steering mirror. Image processing based on the Open CV library was performed to obtain the tool wear area from the captured clear tool image. In addition, the on-machine detection technique was applied to a milling process with an industrial robot and exhibits great effectiveness.
The on-machine detection technique can realize the real-time monitoring of a tool in working state, which is of the significance to identify quality issues of the tool in time and improves the detection efficiency. Based on the machine vision techniques, a fast steering mirror was used to assist industrial camera in capturing clear tool images, and an image acquisition system was established in this paper. A control program was developed by investigating the deflection model for the fast steering mirror. Image processing based on the Open CV library was performed to obtain the tool wear area from the captured clear tool image. In addition, the on-machine detection technique was applied to a milling process with an industrial robot and exhibits great effectiveness.
2021, 40(10): 1541-1548.
doi: 10.13433/j.cnki.1003-8728.20200250
Abstract:
In order to optimize the process parameters of the outer ring raceway in the ELID forming grinding of ball bearings, the effects of the grinding parameters and electrolytic parameters on the grinding wheel wear and workpiece surface roughness in the ELID forming grinding process were studied by multi factor orthogonal test. And the grinding was evaluated by two indexes of grinding wheel radial wear and workpiece surface roughness. The results showed that the radial feed speed of grinding parameters has the greatest influence on the radial wear of grinding wheel, and the wheel rotation speed has the greatest influence on the surface roughness of workpiece; the duty ratio of electrolytic parameters has a greater influence on the radial wear of grinding wheel, and the electrolytic voltage has a greater influence on the surface roughness of workpiece; the grinding effect is the best at a grinding wheel rotation speed of 18 000 r/min, workpiece rotation speed of 100 r/min, radial feed speed of 1 μm/min, duty cycle of 50%, and an electrolytic voltage of 90 V(6.7 Ω).
In order to optimize the process parameters of the outer ring raceway in the ELID forming grinding of ball bearings, the effects of the grinding parameters and electrolytic parameters on the grinding wheel wear and workpiece surface roughness in the ELID forming grinding process were studied by multi factor orthogonal test. And the grinding was evaluated by two indexes of grinding wheel radial wear and workpiece surface roughness. The results showed that the radial feed speed of grinding parameters has the greatest influence on the radial wear of grinding wheel, and the wheel rotation speed has the greatest influence on the surface roughness of workpiece; the duty ratio of electrolytic parameters has a greater influence on the radial wear of grinding wheel, and the electrolytic voltage has a greater influence on the surface roughness of workpiece; the grinding effect is the best at a grinding wheel rotation speed of 18 000 r/min, workpiece rotation speed of 100 r/min, radial feed speed of 1 μm/min, duty cycle of 50%, and an electrolytic voltage of 90 V(6.7 Ω).
2021, 40(10): 1549-1554.
doi: 10.13433/j.cnki.1003-8728.20200243
Abstract:
In view of the difficult machining characteristics of titanium alloy, the limitations and low efficiency of EDM & ECM serial machining, silicon carbide abrasive was added into the deionized water with low resistance, and simultaneous EDM and ECM machining assisted by abrasive was carried out. Taking material removal rate, tool wear rate and surface roughness as the evaluation indexes, the multi process objectives are transformed into a single evaluation index by using the orthogonal test and grey correlation analysis, and the optimized combination of main process parameters, such as peak current, pulse on time, abrasive concentration and discharge voltage, is obtained and verified via experiments. The results show that the tool wear rate, surface roughness and surface morphology are obviously improved at a peak current of 1.5 A, pulse on time of 30 μs, abrasive concentration of 5 g/L and discharge voltage of 40 V.
In view of the difficult machining characteristics of titanium alloy, the limitations and low efficiency of EDM & ECM serial machining, silicon carbide abrasive was added into the deionized water with low resistance, and simultaneous EDM and ECM machining assisted by abrasive was carried out. Taking material removal rate, tool wear rate and surface roughness as the evaluation indexes, the multi process objectives are transformed into a single evaluation index by using the orthogonal test and grey correlation analysis, and the optimized combination of main process parameters, such as peak current, pulse on time, abrasive concentration and discharge voltage, is obtained and verified via experiments. The results show that the tool wear rate, surface roughness and surface morphology are obviously improved at a peak current of 1.5 A, pulse on time of 30 μs, abrasive concentration of 5 g/L and discharge voltage of 40 V.
2021, 40(10): 1555-1560.
doi: 10.13433/j.cnki.1003-8728.20200235
Abstract:
Permanent magnet vernier machine (PMVM) has the advantages of high torque density, direct drive and so on. It has a good development prospect in the low speed, large torque and wide speed range operation fields. In this paper, a new double-stator PMVM is developed. The structure, working principle and magnetic circuit trend of the machine are introduced. The machine is simulated with 4 pole-pairs in both inner and outer stator. The finite element method is used to carry out comparative simulation analysis with magnetic insulation layer inside the rotor. The results show that the new double-stator PMVM without magnetic insulation layer has the advantages of high rotor space utilization rate, low saturation degree and harmonic content, excellent air gap magnetic field speed-up effect and good sinusoidal output voltage waveform. The torque ripple is reduced and the performance of the machine is improved by opening the auxiliary slots to outer stator teeth.
Permanent magnet vernier machine (PMVM) has the advantages of high torque density, direct drive and so on. It has a good development prospect in the low speed, large torque and wide speed range operation fields. In this paper, a new double-stator PMVM is developed. The structure, working principle and magnetic circuit trend of the machine are introduced. The machine is simulated with 4 pole-pairs in both inner and outer stator. The finite element method is used to carry out comparative simulation analysis with magnetic insulation layer inside the rotor. The results show that the new double-stator PMVM without magnetic insulation layer has the advantages of high rotor space utilization rate, low saturation degree and harmonic content, excellent air gap magnetic field speed-up effect and good sinusoidal output voltage waveform. The torque ripple is reduced and the performance of the machine is improved by opening the auxiliary slots to outer stator teeth.
2021, 40(10): 1561-1566.
doi: 10.13433/j.cnki.1003-8728.20200238
Abstract:
The thin films with hydrophobicity of micro-pyramid arrays were fabricated with the UV(Ultraviolet) imprinting method, and the orthogonal experiments were designed to explore the effect of the each process on the microstructure forming, an optimized plan (pressure 0.5 ~ 0.8 MPa, forming time 30 s, curing time 1 min) of micro-pyramid array film with high integrity was obtained. Through the analysis of its anti-reflection performance, the prepared micro-pyramid array film had a weighted reflectivity of 5% lower than that of the non-textured film. By analyzing the various influencing factors, it is found that the suppression of bubble defects, and control of the micro-pyramid characteristic structure parameter height and side angle accuracy could increase the anti-reflection ability of the micro-textured film by 21%, while the contact angle of water drop on the textured film indicated that it has the self-cleaning properties.
The thin films with hydrophobicity of micro-pyramid arrays were fabricated with the UV(Ultraviolet) imprinting method, and the orthogonal experiments were designed to explore the effect of the each process on the microstructure forming, an optimized plan (pressure 0.5 ~ 0.8 MPa, forming time 30 s, curing time 1 min) of micro-pyramid array film with high integrity was obtained. Through the analysis of its anti-reflection performance, the prepared micro-pyramid array film had a weighted reflectivity of 5% lower than that of the non-textured film. By analyzing the various influencing factors, it is found that the suppression of bubble defects, and control of the micro-pyramid characteristic structure parameter height and side angle accuracy could increase the anti-reflection ability of the micro-textured film by 21%, while the contact angle of water drop on the textured film indicated that it has the self-cleaning properties.
2021, 40(10): 1567-1573.
doi: 10.13433/j.cnki.1003-8728.20200245
Abstract:
Aiming at the problems of low efficiency, complicated calculation, and noticeable deviation from practical application in the existing structural design methods of ultrasonic transducer, a new structural optimization method based on finite element modal frequency sensitivity is proposed. Taking the longitudinal-torsional composite ultrasonic transducer as an example, the structural parameters of the transducer are preliminarily determined from the angle of combining the traditional analytical method with the practical application of dimensional boundary constraints. On this basis, we adopted the modal frequency sensitivity method to optimize the transducer structure in line with practical application by changing the critical structural parameters that have a significant influence on the modal frequency of the transducer. The structural model is verified by impedance analysis and amplitude test tests. The experimental results show that the resonant frequency of the transducer is 27.6 kHz, the longitudinal amplitude is 4 μm, the torsional amplitude is 1.33 μm, and the longitudinal-torsional amplitude ratio is 33.25%. Compared with the simulation value, the error is small, and the longitudinal-torsional composite vibration can be realized. The resonant frequency, amplitude, and impedance can meet most requirements of ultrasonic processing, which verifies the effectiveness and rationality of the structural design design method.
Aiming at the problems of low efficiency, complicated calculation, and noticeable deviation from practical application in the existing structural design methods of ultrasonic transducer, a new structural optimization method based on finite element modal frequency sensitivity is proposed. Taking the longitudinal-torsional composite ultrasonic transducer as an example, the structural parameters of the transducer are preliminarily determined from the angle of combining the traditional analytical method with the practical application of dimensional boundary constraints. On this basis, we adopted the modal frequency sensitivity method to optimize the transducer structure in line with practical application by changing the critical structural parameters that have a significant influence on the modal frequency of the transducer. The structural model is verified by impedance analysis and amplitude test tests. The experimental results show that the resonant frequency of the transducer is 27.6 kHz, the longitudinal amplitude is 4 μm, the torsional amplitude is 1.33 μm, and the longitudinal-torsional amplitude ratio is 33.25%. Compared with the simulation value, the error is small, and the longitudinal-torsional composite vibration can be realized. The resonant frequency, amplitude, and impedance can meet most requirements of ultrasonic processing, which verifies the effectiveness and rationality of the structural design design method.
2021, 40(10): 1574-1580.
doi: 10.13433/j.cnki.1003-8728.20200501
Abstract:
The cutting fluid of multi-component sprayed with inline mixing can effectively improve the lubrication and cooling efficacy of the machining zone. Therefore, a kind of mixer with differing structure parameters for inline mixing cutting fluids is proposed and designed. The inline mixing performance of the mixer with a multi-injection structure and the liquid inlet at the middle of the mixing tube is simulated and tested. Results show that the uniformity index (γa) and the coefficient of variation (CV) value obtained by numerical simulation are 0.873 4 and 0.363 8, respectively, which are higher than those of other mixers. Based on the actual distribution of droplets on the water-sensitive paper, the γa and CV values are 0.892 8 and 0.284 4, respectively, which are similar to the results obtained by numerical simulations. The tests proves the feasibility of uniformity analysis based on numerical simulation, and further shows that the proposed mixer has excellent performance and can be used in inline mixing cutting fluids under actual minimal quantity lubrication conditions.
The cutting fluid of multi-component sprayed with inline mixing can effectively improve the lubrication and cooling efficacy of the machining zone. Therefore, a kind of mixer with differing structure parameters for inline mixing cutting fluids is proposed and designed. The inline mixing performance of the mixer with a multi-injection structure and the liquid inlet at the middle of the mixing tube is simulated and tested. Results show that the uniformity index (γa) and the coefficient of variation (CV) value obtained by numerical simulation are 0.873 4 and 0.363 8, respectively, which are higher than those of other mixers. Based on the actual distribution of droplets on the water-sensitive paper, the γa and CV values are 0.892 8 and 0.284 4, respectively, which are similar to the results obtained by numerical simulations. The tests proves the feasibility of uniformity analysis based on numerical simulation, and further shows that the proposed mixer has excellent performance and can be used in inline mixing cutting fluids under actual minimal quantity lubrication conditions.
2021, 40(10): 1581-1589.
doi: 10.13433/j.cnki.1003-8728.20200209
Abstract:
The cutting tool is one of the most active factors in the machining, its status directly affects the surface quality of the workpiece. To accurately identify tool wear, a recognition method combining deep learning with multi-signal fusion was proposed. Based on the autoencoder network, the stacked sparse autoencoder network was constructed. The force signal, vibration signal and acoustic emission signal were collected under different wear condition of milling cutter, and the wavelet packet decomposition was carried out to obtain the time-frequency characteristics of milling cutter wear. The stacked sparse autoencoder network was trained by using the unsupervised learning and supervised learning, a recognition model for wear state of milling tool based on the deep learning was established. The results show that the deep learning model combing with the multi-signal fusion has an accuracy rate of 94.44% for identifying the wear state of milling cutter, the results lay a foundation for controlling the optimization of milling process.
The cutting tool is one of the most active factors in the machining, its status directly affects the surface quality of the workpiece. To accurately identify tool wear, a recognition method combining deep learning with multi-signal fusion was proposed. Based on the autoencoder network, the stacked sparse autoencoder network was constructed. The force signal, vibration signal and acoustic emission signal were collected under different wear condition of milling cutter, and the wavelet packet decomposition was carried out to obtain the time-frequency characteristics of milling cutter wear. The stacked sparse autoencoder network was trained by using the unsupervised learning and supervised learning, a recognition model for wear state of milling tool based on the deep learning was established. The results show that the deep learning model combing with the multi-signal fusion has an accuracy rate of 94.44% for identifying the wear state of milling cutter, the results lay a foundation for controlling the optimization of milling process.
2021, 40(10): 1590-1594.
doi: 10.13433/j.cnki.1003-8728.20200248
Abstract:
A two-phase flow droplet microfluidic chip based on magnetic bead method is designed in this paper, which includes a series of continuous biochemical processes for sample purification, amplification and detection, and this chip can be used for rapid nucleic acid detection. First, the dynamic models of magnetic beads and droplets in a two-phase flow system were established, and a magnetic field simulation was performed on the environment of the magnetic bead micelles by means of a finite element simulation platform to obtain the magnetic forces on the magnetic bead micelles of different volumes. Secondly, the three movement states of droplets of different volumes under the action of different volume of magnetic bead micelles are analyzed. Finally the relationship between the magnetic bead micelles, droplet volume and droplet movement is analyzed, and the droplet manipulation diagram is summarized.
A two-phase flow droplet microfluidic chip based on magnetic bead method is designed in this paper, which includes a series of continuous biochemical processes for sample purification, amplification and detection, and this chip can be used for rapid nucleic acid detection. First, the dynamic models of magnetic beads and droplets in a two-phase flow system were established, and a magnetic field simulation was performed on the environment of the magnetic bead micelles by means of a finite element simulation platform to obtain the magnetic forces on the magnetic bead micelles of different volumes. Secondly, the three movement states of droplets of different volumes under the action of different volume of magnetic bead micelles are analyzed. Finally the relationship between the magnetic bead micelles, droplet volume and droplet movement is analyzed, and the droplet manipulation diagram is summarized.
2021, 40(10): 1595-1602.
doi: 10.13433/j.cnki.1003-8728.20200543
Abstract:
In order to solve the trajectory tracking problem of multi-joint manipulator considering external disturbance and modelling error, an adaptive sliding mode control method of disturbance observer for multi-joint manipulator is proposed in this paper. For the disturbance signal, the disturbance observer is used to observe the observable disturbance, and the unknown disturbance is estimated and compensated by designing adaptive law. For the chattering problem in the manipulator control system, a new reaching law is used to design the sliding mode control law to reduce the chattering effect. Finally, the stability of the controlled system is verified by Lyapunov function. The simulation results show that this method can not only effectively weaken the chattering problem, but also overcome the uncertainty caused by external disturbance and modelling error, and ensure the robustness of the system.
In order to solve the trajectory tracking problem of multi-joint manipulator considering external disturbance and modelling error, an adaptive sliding mode control method of disturbance observer for multi-joint manipulator is proposed in this paper. For the disturbance signal, the disturbance observer is used to observe the observable disturbance, and the unknown disturbance is estimated and compensated by designing adaptive law. For the chattering problem in the manipulator control system, a new reaching law is used to design the sliding mode control law to reduce the chattering effect. Finally, the stability of the controlled system is verified by Lyapunov function. The simulation results show that this method can not only effectively weaken the chattering problem, but also overcome the uncertainty caused by external disturbance and modelling error, and ensure the robustness of the system.
2021, 40(10): 1603-1607.
doi: 10.13433/j.cnki.1003-8728.20200553
Abstract:
In order to obtain the greater magnetic induction and smaller mass of the magnetic circuit of high sound pressure level transducer, the finite element simulation model for the internal magnetic circuit structure of high sound pressure level transducer was established via COMSOL Multiphysics simulation software, and the influence of the height difference between the upper magnetic plate and the lower magnetic plate on the magnetic flux density was analyzed. Three basic dimensions of the magnetic circuit structure, the thickness of the permanent magnet, the height difference between the upper magnetic plate and the lower magnetic plate, and the difference between the inner ring radius of the magnetic plate and the inner ring radius of the permanent magnet were optimized by using the parametric scanning method. And the average value of the magnetic flux density of reference line was maximized. With the optimization module, the optimization model was established. After optimization, the average value of the magnetic flux density of the reference line was basically unchanged, and the weight of the magnetic plate was significantly reduced.
In order to obtain the greater magnetic induction and smaller mass of the magnetic circuit of high sound pressure level transducer, the finite element simulation model for the internal magnetic circuit structure of high sound pressure level transducer was established via COMSOL Multiphysics simulation software, and the influence of the height difference between the upper magnetic plate and the lower magnetic plate on the magnetic flux density was analyzed. Three basic dimensions of the magnetic circuit structure, the thickness of the permanent magnet, the height difference between the upper magnetic plate and the lower magnetic plate, and the difference between the inner ring radius of the magnetic plate and the inner ring radius of the permanent magnet were optimized by using the parametric scanning method. And the average value of the magnetic flux density of reference line was maximized. With the optimization module, the optimization model was established. After optimization, the average value of the magnetic flux density of the reference line was basically unchanged, and the weight of the magnetic plate was significantly reduced.
2021, 40(10): 1608-1613.
doi: 10.13433/j.cnki.1003-8728.20200552
Abstract:
This paper proposed a new method for signal denoising and blind separation for fatigue crack propagation acoustic emission, combined ensemble derivative optimization empirical mode decomposition with independent component analysis, based on the analysis of the characteristics of empirical mode decomposition and independent component analysis. Simulated acoustic emission signal and fatigue crack growth test are respectively carried out, the collected acoustic emission signals are de-noised and blind separated by the proposed method, the results show that the interference signals are removed effectively by the method based on ensemble derivative optimization empirical mode decomposition and independent component analysis, the fatigue crack propagation acoustic emission signal is separated accurately. This study lays a foundation of fatigue damage evaluation and residual life prediction.
This paper proposed a new method for signal denoising and blind separation for fatigue crack propagation acoustic emission, combined ensemble derivative optimization empirical mode decomposition with independent component analysis, based on the analysis of the characteristics of empirical mode decomposition and independent component analysis. Simulated acoustic emission signal and fatigue crack growth test are respectively carried out, the collected acoustic emission signals are de-noised and blind separated by the proposed method, the results show that the interference signals are removed effectively by the method based on ensemble derivative optimization empirical mode decomposition and independent component analysis, the fatigue crack propagation acoustic emission signal is separated accurately. This study lays a foundation of fatigue damage evaluation and residual life prediction.
2021, 40(10): 1614-1618.
doi: 10.13433/j.cnki.1003-8728.20200240
Abstract:
In view of the obvious vibration of a reciprocating compressor unit of an electric bus, this article studies the air flow pulsation of one of the pipelines, and the orifice plate is the simplest and most effective method to suppress the air flow pulsation. Although it has been widely used in related industries, it is currently used. The parameters required for each design of the orifice plate are still at the stage of value selection by experience. In view of this situation, the fluid dynamics model of the pipeline system was established according to the computational fluid dynamics (CFD) method, and reasonable boundary conditions were selected. Through numerical simulation, the influence of the different aperture ratio, orifice plate thickness, orifice plate position on airflow pulsation of the pipeline system is analyzed and compared with that of non-perforated plates. Results show that adding an orifice plate with appropriate size parameters does have a good suppression effect on the airflow pulsation of the piping system.
In view of the obvious vibration of a reciprocating compressor unit of an electric bus, this article studies the air flow pulsation of one of the pipelines, and the orifice plate is the simplest and most effective method to suppress the air flow pulsation. Although it has been widely used in related industries, it is currently used. The parameters required for each design of the orifice plate are still at the stage of value selection by experience. In view of this situation, the fluid dynamics model of the pipeline system was established according to the computational fluid dynamics (CFD) method, and reasonable boundary conditions were selected. Through numerical simulation, the influence of the different aperture ratio, orifice plate thickness, orifice plate position on airflow pulsation of the pipeline system is analyzed and compared with that of non-perforated plates. Results show that adding an orifice plate with appropriate size parameters does have a good suppression effect on the airflow pulsation of the piping system.
2021, 40(10): 1619-1628.
doi: 10.13433/j.cnki.1003-8728.20200241
Abstract:
The accuracy of the transmitted torque of wet dual clutch has an important impact on the shift quality, but the friction characteristic of the wet clutches is affected by the factors such as material interactions and thermal degradation of the oil, which affects the accuracy of the transmitted torque. In this paper, a new method for on-line estimating the friction parameters of the wet clutch by using the existing sensors is proposed. Firstly, an adaptive torque observer is designed by which the transmitted torques of the two clutches during gear shifting are estimated by using the existing sensors of the vehicle. Secondly, the clutch engagement phase is divided into the hydrodynamic lubrication phase, the partial lubrication phase and the mechanical contact phase. Then, a friction coefficient model for wet clutch is established based on the Stribeck friction model and the corresponding coefficients are estimated by using the recursive least squares method. Finally, the real-time dynamic friction coefficient model during the shifting phase is acquired by the Stribeck friction model, which provides the basis for online fault diagnosis and the precise control of the transmitted torque of the wet clutch.
The accuracy of the transmitted torque of wet dual clutch has an important impact on the shift quality, but the friction characteristic of the wet clutches is affected by the factors such as material interactions and thermal degradation of the oil, which affects the accuracy of the transmitted torque. In this paper, a new method for on-line estimating the friction parameters of the wet clutch by using the existing sensors is proposed. Firstly, an adaptive torque observer is designed by which the transmitted torques of the two clutches during gear shifting are estimated by using the existing sensors of the vehicle. Secondly, the clutch engagement phase is divided into the hydrodynamic lubrication phase, the partial lubrication phase and the mechanical contact phase. Then, a friction coefficient model for wet clutch is established based on the Stribeck friction model and the corresponding coefficients are estimated by using the recursive least squares method. Finally, the real-time dynamic friction coefficient model during the shifting phase is acquired by the Stribeck friction model, which provides the basis for online fault diagnosis and the precise control of the transmitted torque of the wet clutch.
2021, 40(10): 1629-1635.
doi: 10.13433/j.cnki.1003-8728.20200237
Abstract:
Taking the traditional concave hexagon Poisson′s ratio structure as the main reference object, a relatively complete negative Poisson′s ratio element optimization structure was obtained through topology optimization, and six elementary geometric models were established based on this structure. The differences in the performance of honeycomb structures under different honeycomb arrangements were discussed, and the impact simulation study on the honeycomb structure established by six kinds of elements was carried out by selecting suitable arrangements. Taking the energy absorption, specific energy absorption, peak crushing force and structural equivalent Poisson′s ratio as evaluation indexes, the structural performance of different element honeycomb structures was compared and analyzed, and the element structure with the best comprehensive performance was selected. The front-end structure of the car was selected, and the traditional concave hexagon structure and the optimal element structure were three-dimensionally arranged and combined into the energy absorbing box, and the application of the front-end collision of the car was compared. The results show that each element structure based on topology optimization is higher in energy absorption effect and load-bearing capacity than the traditional concave hexagon structure. The selected optimal element structure has better energy absorption effect and negative Poisson′s ratio characteristics in the front-end collision application of automobiles, and its crushing distance is greatly reduced.
Taking the traditional concave hexagon Poisson′s ratio structure as the main reference object, a relatively complete negative Poisson′s ratio element optimization structure was obtained through topology optimization, and six elementary geometric models were established based on this structure. The differences in the performance of honeycomb structures under different honeycomb arrangements were discussed, and the impact simulation study on the honeycomb structure established by six kinds of elements was carried out by selecting suitable arrangements. Taking the energy absorption, specific energy absorption, peak crushing force and structural equivalent Poisson′s ratio as evaluation indexes, the structural performance of different element honeycomb structures was compared and analyzed, and the element structure with the best comprehensive performance was selected. The front-end structure of the car was selected, and the traditional concave hexagon structure and the optimal element structure were three-dimensionally arranged and combined into the energy absorbing box, and the application of the front-end collision of the car was compared. The results show that each element structure based on topology optimization is higher in energy absorption effect and load-bearing capacity than the traditional concave hexagon structure. The selected optimal element structure has better energy absorption effect and negative Poisson′s ratio characteristics in the front-end collision application of automobiles, and its crushing distance is greatly reduced.
2021, 40(10): 1636-1640.
doi: 10.13433/j.cnki.1003-8728.20200253
Abstract:
The locking seat is a commonly used locking and releasing mechanism in aerospace engineering. During the running status, the slipping of contact surface in locking seat often occurs due to vibration, resulting in the lock failure. In order to solve this problem, a set of sliding recognition system of lock seat is proposed. Firstly, the constitutive relation curve of the locking seat is obtained through calibration test. Then the locking device model of the overlapped antenna is designed and processed, and the vibration test is carried out. The strain data and acceleration response data of locking device are collected separately during the test. Finally, the analysis results of the two measurement methods are compared, which shows that the method of the sliding recognition system of the lock seat is accurate and effective.
The locking seat is a commonly used locking and releasing mechanism in aerospace engineering. During the running status, the slipping of contact surface in locking seat often occurs due to vibration, resulting in the lock failure. In order to solve this problem, a set of sliding recognition system of lock seat is proposed. Firstly, the constitutive relation curve of the locking seat is obtained through calibration test. Then the locking device model of the overlapped antenna is designed and processed, and the vibration test is carried out. The strain data and acceleration response data of locking device are collected separately during the test. Finally, the analysis results of the two measurement methods are compared, which shows that the method of the sliding recognition system of the lock seat is accurate and effective.
