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RSS2022 Vol. 41, No. 5
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2022, 41(5): 657-665.
doi: 10.13433/j.cnki.1003-8728.20200404
PDF 4461KB
Abstract:
Conventional development of oil and gas fields can no longer meet the needs of people. In the exploration and development of horizontal wells, large displacement wells and other complicated wells, some problems such as difficult to control the well trajectory, low the rate of mechanical penetration and the support pressure of the drill string will bring great challenges to the drilling process. In order to solve the above problems, a negative-pressure pulsed hydraulic oscillator tool is designed to reduce the friction resistance of horizontal wells and large-displacement wells, and the structural principle of negative-pressure pulsed oscillating tool is analyzed in detail. The hydrodynamic characteristics of the negative pressure pulsed hydraulic oscillator are analyzed by using the kinematic analysis results, and combined with the relevant example parameters. Results show that when the fluid flow of the input tool is constant, the larger the radial nozzle diameter of the valve shaft system, the greater the pressure drop of the tool and the water hammer pressure generated, so the greater the axial force impact force generated. The accuracy of the theoretical calculation is verified by the results of finite element fluid simulation, which provides a theoretical basis for the field application selection and drilling acceleration of the negative-pressure pulsed hydraulic oscillator tool in the future.
Conventional development of oil and gas fields can no longer meet the needs of people. In the exploration and development of horizontal wells, large displacement wells and other complicated wells, some problems such as difficult to control the well trajectory, low the rate of mechanical penetration and the support pressure of the drill string will bring great challenges to the drilling process. In order to solve the above problems, a negative-pressure pulsed hydraulic oscillator tool is designed to reduce the friction resistance of horizontal wells and large-displacement wells, and the structural principle of negative-pressure pulsed oscillating tool is analyzed in detail. The hydrodynamic characteristics of the negative pressure pulsed hydraulic oscillator are analyzed by using the kinematic analysis results, and combined with the relevant example parameters. Results show that when the fluid flow of the input tool is constant, the larger the radial nozzle diameter of the valve shaft system, the greater the pressure drop of the tool and the water hammer pressure generated, so the greater the axial force impact force generated. The accuracy of the theoretical calculation is verified by the results of finite element fluid simulation, which provides a theoretical basis for the field application selection and drilling acceleration of the negative-pressure pulsed hydraulic oscillator tool in the future.
2022, 41(5): 666-672.
doi: 10.13433/j.cnki.1003-8728.20200388
Abstract:
Aiming at the state features in the vibration signal of rolling bearing operation which are difficult to distinguish, a method of constructing feature vectors combined with parameter optimization variational modal decomposition (VMD) and optimal multi-scale permutation entropy (OMPE) is proposed, and support vector machine (SVM) is next used to diagnose faults. The decomposition result of VMD is limited by the number of decompositions and the penalty factor, and the quantum particle swarm optimization (QPSO) is used to achieve the optimal effect of decomposition. Considering the periodic nature of bearing operation, the concept of optimal multi-scale permutation entropy based on the period characteristics of bearing fault operation is proposed, and the feature vector is constructed by combining modal components and optimal-scale permutation entropy. Using support vector machine identification and comparative analysis through different methods shows that the proposed method can effectively extract features and improve the accuracy of rolling bearing fault diagnosis.
Aiming at the state features in the vibration signal of rolling bearing operation which are difficult to distinguish, a method of constructing feature vectors combined with parameter optimization variational modal decomposition (VMD) and optimal multi-scale permutation entropy (OMPE) is proposed, and support vector machine (SVM) is next used to diagnose faults. The decomposition result of VMD is limited by the number of decompositions and the penalty factor, and the quantum particle swarm optimization (QPSO) is used to achieve the optimal effect of decomposition. Considering the periodic nature of bearing operation, the concept of optimal multi-scale permutation entropy based on the period characteristics of bearing fault operation is proposed, and the feature vector is constructed by combining modal components and optimal-scale permutation entropy. Using support vector machine identification and comparative analysis through different methods shows that the proposed method can effectively extract features and improve the accuracy of rolling bearing fault diagnosis.
2022, 41(5): 673-680.
doi: 10.13433/j.cnki.1003-8728.20200509
Abstract:
In order to improve the traction performance of working machinery on soft sand, a sandy track shoe based on the mechanism of ostrich feet travelling on sand was designed. The structural parameters of the track shoe were set as the object, and a mathematical model for tractive force between the track shoe and the sand was established. Combined with the orthogonal experiment, the finite element analysis about the motion of different track shoes on sand was carried out. And the feasibility of the track shoe was verified through real vehicle test. The results show that: the track shoe width and track grouser height are the key factors affecting ground traction force; for the preferred track shoe, when one track shoe is added, the shear force increases by about 30%.
In order to improve the traction performance of working machinery on soft sand, a sandy track shoe based on the mechanism of ostrich feet travelling on sand was designed. The structural parameters of the track shoe were set as the object, and a mathematical model for tractive force between the track shoe and the sand was established. Combined with the orthogonal experiment, the finite element analysis about the motion of different track shoes on sand was carried out. And the feasibility of the track shoe was verified through real vehicle test. The results show that: the track shoe width and track grouser height are the key factors affecting ground traction force; for the preferred track shoe, when one track shoe is added, the shear force increases by about 30%.
2022, 41(5): 681-687.
doi: 10.13433/j.cnki.1003-8728.20220035
Abstract:
In order to study mechanical characteristics of composite gear meshing, a parametric design method of three-dimensional five directional braided composite gear is proposed. Based on the consideration of braiding angle and fiber bundle cross-section shape, the mechanical properties of composite cell at meso-scale are analyzed by using the finite element method, and compared with the experimental results. On the above mentioned basis and in terms of the homogenization, the relationship between the mechanical properties of composite and the gear is established, and then the finite element model for composite gear meshing is constructed. The meshing process is simulated and analyzed, and the contact stress of tooth surface and bending stress of root, the fatigue risk points of contact and bending, and the matching relationship between the loading conditions and the contact stress, bending stress are obtained. The analysis results is according with the Hertz contact law, which provides theoretical support for the performance analysis of carbon fiber three-dimensional braided composites and gears.
In order to study mechanical characteristics of composite gear meshing, a parametric design method of three-dimensional five directional braided composite gear is proposed. Based on the consideration of braiding angle and fiber bundle cross-section shape, the mechanical properties of composite cell at meso-scale are analyzed by using the finite element method, and compared with the experimental results. On the above mentioned basis and in terms of the homogenization, the relationship between the mechanical properties of composite and the gear is established, and then the finite element model for composite gear meshing is constructed. The meshing process is simulated and analyzed, and the contact stress of tooth surface and bending stress of root, the fatigue risk points of contact and bending, and the matching relationship between the loading conditions and the contact stress, bending stress are obtained. The analysis results is according with the Hertz contact law, which provides theoretical support for the performance analysis of carbon fiber three-dimensional braided composites and gears.
2022, 41(5): 688-694.
doi: 10.13433/j.cnki.1003-8728.20200425
Abstract:
Aiming at the problems that the fault diagnosis of reciprocating machinery equipment is easily affected by speed fluctuations and the deep network diagnosis model is complicated and poor in robustness, a one-dimensional improved LeNet-5 mechanical fault diagnosis method was proposed, and the effects of sliding window and order sampling data sample construction method are compared and analyzed. Based on the classic model LeNet-5, a simple and compact one-dimensional convolutional neural network diagnosis model was constructed, which only contains two convolution modules, a single fully connected layer and an output layer. And its convolution module combines the batch normalization layer and Relu layers to improve training speed and network generalization ability, and use overlapping pooling windows and random inactivation to alleviate network overfitting. Using the open source bearing data set of Case Western Reserve University to verify, the fault detection accuracy under 12 working conditions can reach 99.82%. Aiming at the influence of speed fluctuation of reciprocating machinery, the method of constructing data samples of order sampling is adopted to improve the quality of training sample data of the network model. Under the condition of order sampling of diesel engine, good training results can be achieved under the condition of small samples.
Aiming at the problems that the fault diagnosis of reciprocating machinery equipment is easily affected by speed fluctuations and the deep network diagnosis model is complicated and poor in robustness, a one-dimensional improved LeNet-5 mechanical fault diagnosis method was proposed, and the effects of sliding window and order sampling data sample construction method are compared and analyzed. Based on the classic model LeNet-5, a simple and compact one-dimensional convolutional neural network diagnosis model was constructed, which only contains two convolution modules, a single fully connected layer and an output layer. And its convolution module combines the batch normalization layer and Relu layers to improve training speed and network generalization ability, and use overlapping pooling windows and random inactivation to alleviate network overfitting. Using the open source bearing data set of Case Western Reserve University to verify, the fault detection accuracy under 12 working conditions can reach 99.82%. Aiming at the influence of speed fluctuation of reciprocating machinery, the method of constructing data samples of order sampling is adopted to improve the quality of training sample data of the network model. Under the condition of order sampling of diesel engine, good training results can be achieved under the condition of small samples.
2022, 41(5): 695-702.
doi: 10.13433/j.cnki.1003-8728.20200429
Abstract:
A multi-scale extend finite element method (XFEM) for analyzing the dynamic fracture of elastic solids is proposed. The present method uses local mesh refinement to process the cracks in the mesh model, and variable-node elements is used to connect different scale mesh elements, which saves calculation costs on the basis of improving the accuracy of numerical calculations; implicit Newmark time integration and the interaction integral is used to solve the dynamic intensity factor. The calculated results of the calculation examples are compared with those of the existing literature to verify the pros and cons of the method. The results show that the multi-scale XFEM is an effective numerical method for simulating the dynamic fracture of elastic structures, and it has higher accuracy than the standard XFEM.
A multi-scale extend finite element method (XFEM) for analyzing the dynamic fracture of elastic solids is proposed. The present method uses local mesh refinement to process the cracks in the mesh model, and variable-node elements is used to connect different scale mesh elements, which saves calculation costs on the basis of improving the accuracy of numerical calculations; implicit Newmark time integration and the interaction integral is used to solve the dynamic intensity factor. The calculated results of the calculation examples are compared with those of the existing literature to verify the pros and cons of the method. The results show that the multi-scale XFEM is an effective numerical method for simulating the dynamic fracture of elastic structures, and it has higher accuracy than the standard XFEM.
2022, 41(5): 703-710.
doi: 10.13433/j.cnki.1003-8728.20200412
Abstract:
The simplified vibration model of the vehicle was developed to study the nonlinear response behavior of vertical vibration of automobile body. The influence of geometric nonliearity and nonliear magnetorheological damping force of the suspension system on the vehicle vertical vibration behavior are analyzed with the combined simulation method of SolidWorks and SimMechanics, and the variation of the second and higher superharmonic components with system parameters in vertical displacement response of automobile body are discussed. The simulation results show that the second and higher superharmonic components appear in the system responses, the second and the third superharmonic resonance will be generated under the specific excitation frequencies and amplitudes. These show obvious nonlinear vibration behaviors that will lead to poor ride comfort. The work will be helpful to the optimization design of suspension system with magnetorheological damper.
The simplified vibration model of the vehicle was developed to study the nonlinear response behavior of vertical vibration of automobile body. The influence of geometric nonliearity and nonliear magnetorheological damping force of the suspension system on the vehicle vertical vibration behavior are analyzed with the combined simulation method of SolidWorks and SimMechanics, and the variation of the second and higher superharmonic components with system parameters in vertical displacement response of automobile body are discussed. The simulation results show that the second and higher superharmonic components appear in the system responses, the second and the third superharmonic resonance will be generated under the specific excitation frequencies and amplitudes. These show obvious nonlinear vibration behaviors that will lead to poor ride comfort. The work will be helpful to the optimization design of suspension system with magnetorheological damper.
2022, 41(5): 711-720.
doi: 10.13433/j.cnki.1003-8728.20200378
Abstract:
A passive hip joint with four degrees of freedom is designed to assist the exoskeleton, which not only helps the carrier reduce the hip force, but also increases the range of hip abduction/adduction. Firstly, biomechanical analysis of the handling posture is made, and an exoskeleton plan is proposed and labor-saving materials are selected. Then the change in the torque of the hip joint through ADAMS dynamic simulation is analyzed to verify the labor saving degree of the three materials; and the strength of the three elastic rod materials is statically analyzed; the labor saving degree of the device under smaller working conditions is studied again, and the CATIA ergonomics module is finally used to analyze the comfort degree of the human body when carrying a posture with the hip joint two and four degrees of freedom. The simulation results show that the present exoskeleton device designed has outstanding labor-saving effects. The labor-saving range of the selected materials is 63% labor saving when carrying 5-25 kg heavy objects. At the same time, it has a high comfort degree and effective plan for studying subsequent exoskeleton.
A passive hip joint with four degrees of freedom is designed to assist the exoskeleton, which not only helps the carrier reduce the hip force, but also increases the range of hip abduction/adduction. Firstly, biomechanical analysis of the handling posture is made, and an exoskeleton plan is proposed and labor-saving materials are selected. Then the change in the torque of the hip joint through ADAMS dynamic simulation is analyzed to verify the labor saving degree of the three materials; and the strength of the three elastic rod materials is statically analyzed; the labor saving degree of the device under smaller working conditions is studied again, and the CATIA ergonomics module is finally used to analyze the comfort degree of the human body when carrying a posture with the hip joint two and four degrees of freedom. The simulation results show that the present exoskeleton device designed has outstanding labor-saving effects. The labor-saving range of the selected materials is 63% labor saving when carrying 5-25 kg heavy objects. At the same time, it has a high comfort degree and effective plan for studying subsequent exoskeleton.
2022, 41(5): 721-728.
doi: 10.13433/j.cnki.1003-8728.20200398
Abstract:
This paper proposes a novel non-probabilistic reliability sensitivity analysis method and uses the multi-ellipsoid model to describe the multi-source uncertainties of a structure. It takes the non-probabilistic reliability index as the measure of non-probabilistic reliability and gives the solutions of non-probabilistic reliability indices of a linear limit state function and a nonlinear limit state function respectively. It develops an approximate analytical method for non-probabilistic reliability sensitivity analysis and defines reliability sensitivity as the partial derivative of the non-probabilistic reliability index with respect to uncertain variable's mean value, interval radius and correlation coefficient. The generality and wide applicability of the multi-ellipsoid model's reliability sensitivity analysis method compared with those for interval model and ellipsoid model are discussed. Three numerical examples are utilized to verify the feasibility and superiority of the proposed method.
This paper proposes a novel non-probabilistic reliability sensitivity analysis method and uses the multi-ellipsoid model to describe the multi-source uncertainties of a structure. It takes the non-probabilistic reliability index as the measure of non-probabilistic reliability and gives the solutions of non-probabilistic reliability indices of a linear limit state function and a nonlinear limit state function respectively. It develops an approximate analytical method for non-probabilistic reliability sensitivity analysis and defines reliability sensitivity as the partial derivative of the non-probabilistic reliability index with respect to uncertain variable's mean value, interval radius and correlation coefficient. The generality and wide applicability of the multi-ellipsoid model's reliability sensitivity analysis method compared with those for interval model and ellipsoid model are discussed. Three numerical examples are utilized to verify the feasibility and superiority of the proposed method.
2022, 41(5): 729-736.
doi: 10.13433/j.cnki.1003-8728.20200314
Abstract:
Aiming at the early failure of the check valve of the reciprocating high-pressure diaphragm pump, the vibration signal contains a large amount of background noise, causing the feature information to be submerged by noise, a removing noise method of improved complete ensemble empirical mode decomposition (ICEEMD) and Hausdorff distance (HD) in check valve early fault signal is proposed. First of all, ICEEMD was used to decompose the acquired signal into multiple intrinsic modal functions (IMF). Then, calculating the Hausdorff distance of the probability density function of each IMF component and the original signal, and HD was used to separate noisy IMF components from IMF components decomposed by ICEEMD. Next, the kurtosis as an indicator, was used to select the IMF component with a larger kurtosis value for reconstruction. Finally, Hilbert envelope was used to demodulate the reconstructed signal, and conduct comparative tests to analyze the noise reduction effect. The simulation results show that the method can effectively extract the feature frequency of the signal under strong noise, and the experimental results of the measured data show that the proposed method can effectively extract the fundamental frequency and its multiplied frequency of check valve submerged by noise, and has a good noise reduction effect.
Aiming at the early failure of the check valve of the reciprocating high-pressure diaphragm pump, the vibration signal contains a large amount of background noise, causing the feature information to be submerged by noise, a removing noise method of improved complete ensemble empirical mode decomposition (ICEEMD) and Hausdorff distance (HD) in check valve early fault signal is proposed. First of all, ICEEMD was used to decompose the acquired signal into multiple intrinsic modal functions (IMF). Then, calculating the Hausdorff distance of the probability density function of each IMF component and the original signal, and HD was used to separate noisy IMF components from IMF components decomposed by ICEEMD. Next, the kurtosis as an indicator, was used to select the IMF component with a larger kurtosis value for reconstruction. Finally, Hilbert envelope was used to demodulate the reconstructed signal, and conduct comparative tests to analyze the noise reduction effect. The simulation results show that the method can effectively extract the feature frequency of the signal under strong noise, and the experimental results of the measured data show that the proposed method can effectively extract the fundamental frequency and its multiplied frequency of check valve submerged by noise, and has a good noise reduction effect.
2022, 41(5): 737-746.
doi: 10.13433/j.cnki.1003-8728.20200357
Abstract:
Aiming at the changes in vibration characteristics of bladed disk due to radial opening cracks at the outer edge of the disk, this paper studies the natural characteristics and response characteristics of the blade disk using the finite element method, and experiments are carried out to verify the natural characteristics simulation results. The influence law of different position and length cracks on the vibration characteristics of the bladed disk with cracks is obtained. The research result shows that: in terms of natural characteristics, the crack closer is to the root, the longer the length, the greater the natural frequency reduction of the disk, and the greater the modal localization parameters(MLP); In the frequency veering area, MLP increase more obviously. In terms of forced vibration response, in the frequency veering area, the disk crack separates the resonance frequency and the resonance frequency range becomes wider, the crack closer is to the root, the longer the length, the larger the vibration response localization parameter.
Aiming at the changes in vibration characteristics of bladed disk due to radial opening cracks at the outer edge of the disk, this paper studies the natural characteristics and response characteristics of the blade disk using the finite element method, and experiments are carried out to verify the natural characteristics simulation results. The influence law of different position and length cracks on the vibration characteristics of the bladed disk with cracks is obtained. The research result shows that: in terms of natural characteristics, the crack closer is to the root, the longer the length, the greater the natural frequency reduction of the disk, and the greater the modal localization parameters(MLP); In the frequency veering area, MLP increase more obviously. In terms of forced vibration response, in the frequency veering area, the disk crack separates the resonance frequency and the resonance frequency range becomes wider, the crack closer is to the root, the longer the length, the larger the vibration response localization parameter.
2022, 41(5): 747-754.
doi: 10.13433/j.cnki.1003-8728.20200356
Abstract:
Inverse kinematics is the basis of motion control, trajectory planning and dynamics analysis of redundant robots, and it is also one of the most important problems in robotics. Aiming at the minimum error of the position and pose of the end effecter as the optimization objective, the fitness function is established, and the inverse kinematics problem of redundant manipulator is transformed into an equivalent optimization problem. Based on the swarm intelligence optimization algorithm, the hybrid mutation fruit fly optimization algorithm (HMFOA) is applied to solve the inverse kinematics problem of redundant manipulator. Using olfactory search hybrid mutation mechanism and visual search dynamic real-time update mechanism can effectively solve the convergence problem of fruit fly optimization algorithm (FOA) and improve the convergence speed of the algorithm. In order to further verify the effectiveness of HMFOA, HMFOA is tested on a 7-DOF manipulator, and the results are compared with FOA, LGMS-FOA and AE-LGMS-FOA. The experimental results show that HMFOA can effectively solve the inverse kinematics problem of redundant manipulators.
Inverse kinematics is the basis of motion control, trajectory planning and dynamics analysis of redundant robots, and it is also one of the most important problems in robotics. Aiming at the minimum error of the position and pose of the end effecter as the optimization objective, the fitness function is established, and the inverse kinematics problem of redundant manipulator is transformed into an equivalent optimization problem. Based on the swarm intelligence optimization algorithm, the hybrid mutation fruit fly optimization algorithm (HMFOA) is applied to solve the inverse kinematics problem of redundant manipulator. Using olfactory search hybrid mutation mechanism and visual search dynamic real-time update mechanism can effectively solve the convergence problem of fruit fly optimization algorithm (FOA) and improve the convergence speed of the algorithm. In order to further verify the effectiveness of HMFOA, HMFOA is tested on a 7-DOF manipulator, and the results are compared with FOA, LGMS-FOA and AE-LGMS-FOA. The experimental results show that HMFOA can effectively solve the inverse kinematics problem of redundant manipulators.
2022, 41(5): 755-763.
doi: 10.13433/j.cnki.1003-8728.20200405
Abstract:
Aiming at the problem that the inhomogeneous state of the sample in the detection of workpiece surface defects makes it to difficultly construct the detection model, a method of workpiece surface defect detection oriented to uneven sample space is proposed. A serial overall structure (SSE-D Model) including sample space equalization sampling model (SSE Model) and defect detection model (A-C Model) is constructed. SSE Model firstly uses a two-way parallel structure to perform feature extraction and sample region restoration of the original sample, and does single-sample expansion to achieve feature expansion for the extracted features, and finally does Poisson Fusion to achieve the fusion of features and repaired samples to generate New samples and complete the equalization of the sample space. AC Model uses spatially balanced new samples as the input of the detection model, and the deep residual idea to construct the detection model, and integrates the attention mechanism to improve the model's learning ability of defect features. The present model focuses on solving the problem of unbalanced original sample space in surface defect detection of workpiece, and improves the feature learning ability and robustness of the detection model. Finally, five types of workpiece image samples are used to complete the experimental comparison, which verifies the effectiveness of this method and feasibility, it provides a new idea for surface defect detection in unbalanced sample space.
Aiming at the problem that the inhomogeneous state of the sample in the detection of workpiece surface defects makes it to difficultly construct the detection model, a method of workpiece surface defect detection oriented to uneven sample space is proposed. A serial overall structure (SSE-D Model) including sample space equalization sampling model (SSE Model) and defect detection model (A-C Model) is constructed. SSE Model firstly uses a two-way parallel structure to perform feature extraction and sample region restoration of the original sample, and does single-sample expansion to achieve feature expansion for the extracted features, and finally does Poisson Fusion to achieve the fusion of features and repaired samples to generate New samples and complete the equalization of the sample space. AC Model uses spatially balanced new samples as the input of the detection model, and the deep residual idea to construct the detection model, and integrates the attention mechanism to improve the model's learning ability of defect features. The present model focuses on solving the problem of unbalanced original sample space in surface defect detection of workpiece, and improves the feature learning ability and robustness of the detection model. Finally, five types of workpiece image samples are used to complete the experimental comparison, which verifies the effectiveness of this method and feasibility, it provides a new idea for surface defect detection in unbalanced sample space.
2022, 41(5): 764-770.
doi: 10.13433/j.cnki.1003-8728.20200355
Abstract:
The 3D printing technology is widely applied to biomedicine. Since the 3D printing technology based on biomedicine has unique advantages in terms of personalized customization and complex structure control manufacturing, the 3D printing of biological materials or living cells can be used to construct complex biological three-dimensional structures, such as personalized implants, renewable artificial bones, artificial organs and artificial blood vessels, etc. One of the greatest progresses leading to the 3D printing of biomedicines was the development of biomaterials, cells, and the support components for the fabrication of functional living tissues. This paper discusses the research status of the 3D printing technology and its application to biomedicine such as orthopedics, skin tissue, vascular prosthesis and personalized drug development and puts forward its future development direction.
The 3D printing technology is widely applied to biomedicine. Since the 3D printing technology based on biomedicine has unique advantages in terms of personalized customization and complex structure control manufacturing, the 3D printing of biological materials or living cells can be used to construct complex biological three-dimensional structures, such as personalized implants, renewable artificial bones, artificial organs and artificial blood vessels, etc. One of the greatest progresses leading to the 3D printing of biomedicines was the development of biomaterials, cells, and the support components for the fabrication of functional living tissues. This paper discusses the research status of the 3D printing technology and its application to biomedicine such as orthopedics, skin tissue, vascular prosthesis and personalized drug development and puts forward its future development direction.
2022, 41(5): 771-778.
doi: 10.13433/j.cnki.1003-8728.20200375
Abstract:
Because the multi-objective dual resource constrained flexible job shop scheduling has efficiency differences among operators, a flexible workshop scheduling optimization model is established to minimize production time, production cost and green manufacturing evaluation coefficient, and then an improved NSGA-Ⅱ algorithm is proposed. Firstly, the scheduling process is coded through quantum coding, and the niche technology is used to initialize the population and repeated individual control strategy and the entropy weight method selection strategy to improve the quality of the improved NSGA-Ⅱ algorithm. Finally, the comparison of the test results between the NSGA-Ⅱ algorithm and the improved NSGA-Ⅱ algorithm verifies that the improved NSGA-Ⅱ algorithm can solve the above-mentioned flexible job shop scheduling problem.
Because the multi-objective dual resource constrained flexible job shop scheduling has efficiency differences among operators, a flexible workshop scheduling optimization model is established to minimize production time, production cost and green manufacturing evaluation coefficient, and then an improved NSGA-Ⅱ algorithm is proposed. Firstly, the scheduling process is coded through quantum coding, and the niche technology is used to initialize the population and repeated individual control strategy and the entropy weight method selection strategy to improve the quality of the improved NSGA-Ⅱ algorithm. Finally, the comparison of the test results between the NSGA-Ⅱ algorithm and the improved NSGA-Ⅱ algorithm verifies that the improved NSGA-Ⅱ algorithm can solve the above-mentioned flexible job shop scheduling problem.
2022, 41(5): 779-785.
doi: 10.13433/j.cnki.1003-8728.20200424
Abstract:
Comparing with inflatable wheels, non-pneumatic wheels have the advantages of high safety, free inflation, low maintenance cost and low rolling resistance, and they have broad prospects in special scenarios. The non-pneumatic tire is studied, and honeycomb structure is used as a spoke instead of air. A non-pneumatic tire is designed based on chiral honeycomb, and then the influence of the parameters of the chiral honeycomb on the performance is analyzed. Based on the six ligament chiral honeycomb, the four ligament chiral honeycomb and the four ligament backhand honeycomb structures, three type spoke structures were designed. The finite element software ANSYS was used to calculate the bearing capacity and local stress of non-pneumatic tires. Under the same vertical load condition, a finite element analysis was used to examine the influence of the radius of the pitch circle and the wall thickness of the chiral honeycomb on the wheels. The curves of load capacity and maximum Mises stress versus these two parameters were obtained. The present results can be used as a reference for optimizing the non-pneumatic tires with chiral honeycomb spokes.
Comparing with inflatable wheels, non-pneumatic wheels have the advantages of high safety, free inflation, low maintenance cost and low rolling resistance, and they have broad prospects in special scenarios. The non-pneumatic tire is studied, and honeycomb structure is used as a spoke instead of air. A non-pneumatic tire is designed based on chiral honeycomb, and then the influence of the parameters of the chiral honeycomb on the performance is analyzed. Based on the six ligament chiral honeycomb, the four ligament chiral honeycomb and the four ligament backhand honeycomb structures, three type spoke structures were designed. The finite element software ANSYS was used to calculate the bearing capacity and local stress of non-pneumatic tires. Under the same vertical load condition, a finite element analysis was used to examine the influence of the radius of the pitch circle and the wall thickness of the chiral honeycomb on the wheels. The curves of load capacity and maximum Mises stress versus these two parameters were obtained. The present results can be used as a reference for optimizing the non-pneumatic tires with chiral honeycomb spokes.
Prediction of Wheel Tread Wear of High Speed Vehicles and Analysis of Influence of System Parameters
2022, 41(5): 786-794.
doi: 10.13433/j.cnki.1003-8728.20200362
Abstract:
In order to further explore the law of wheel tread wear and its key influencing factors, a wheel tread wear prediction model is established by combining UM and MATLAB, which includes vehicle-track coupled dynamic model, wheel-rail local contact model and wear calculation model. The working condition of the line is arranged according to the characteristics of the actual line, and the evolution law of wheel tread wear is predicted. The vehicle and track parameters are selected to calculate and analyze the influence of the selected parameters on the evolution process of wheel tread wear. The simulation results show that the wheel tread wear is mainly distributed on both sides of the nominal rolling circle. With the increase of operating mileage, the wear amount increases almost linearly. The equivalent taper increases but fluctuates abnormally with the lateral shift of the wheelset. The wheel-rail contact area extends to the outer wheel area but the contact area is gradually localized. The greater the longitudinal stiffness of the pivot arm positioning node, the wider the wear distribution and the greater the wear depth. The wheelbase of the bogie mainly affects the development of wheel wear when the curve passes. Track irregularity is an important factor affecting wheel wear. Rail grinding and wheel-rail profile optimization are effective measures to reduce wheel tread wear.
In order to further explore the law of wheel tread wear and its key influencing factors, a wheel tread wear prediction model is established by combining UM and MATLAB, which includes vehicle-track coupled dynamic model, wheel-rail local contact model and wear calculation model. The working condition of the line is arranged according to the characteristics of the actual line, and the evolution law of wheel tread wear is predicted. The vehicle and track parameters are selected to calculate and analyze the influence of the selected parameters on the evolution process of wheel tread wear. The simulation results show that the wheel tread wear is mainly distributed on both sides of the nominal rolling circle. With the increase of operating mileage, the wear amount increases almost linearly. The equivalent taper increases but fluctuates abnormally with the lateral shift of the wheelset. The wheel-rail contact area extends to the outer wheel area but the contact area is gradually localized. The greater the longitudinal stiffness of the pivot arm positioning node, the wider the wear distribution and the greater the wear depth. The wheelbase of the bogie mainly affects the development of wheel wear when the curve passes. Track irregularity is an important factor affecting wheel wear. Rail grinding and wheel-rail profile optimization are effective measures to reduce wheel tread wear.
2022, 41(5): 795-800.
doi: 10.13433/j.cnki.1003-8728.20220005
Abstract:
Robots need to have the ability of motion control, positioning, mapping and path planning in performing various tasks. Aiming at the problem of traditional A* algorithms that are easy to fall into local optimal points and turning points in path planning, an improved A* (A-Star) and dynamic window approach (DWA) combined hybrid algorithm. The mobile robot platform uses laser sensors as the core sensor to obtain two-dimensional information of the environment. Aiming at the problem of synchronous positioning and mapping, the Lazy Decision algorithm is improved to improve the loop quality and reduce the amount of calculation. In view of the problems in robot path planning, the prediction distance is introduced into the A* algorithm, and the h(n) weight coefficient in the dynamic weighing heuristic A* algorithm is set to solve the problem of using A* algorithm to expand the number of nodes and easily fall into local optimal problem, while correcting the corners in the path planning, effectively reducing the path planning time by 14%. The effectiveness of the method is verified on an autonomous mobile robot system experimental platform composed of a moving chassis, 2D LIDAR sensors and a computer computing platform. The method not only shortens the running time, optimizes the path complexity, and effectively overcomes disadvantages of a large turning angle and multiple turning angles of traditional path planning methods.
Robots need to have the ability of motion control, positioning, mapping and path planning in performing various tasks. Aiming at the problem of traditional A* algorithms that are easy to fall into local optimal points and turning points in path planning, an improved A* (A-Star) and dynamic window approach (DWA) combined hybrid algorithm. The mobile robot platform uses laser sensors as the core sensor to obtain two-dimensional information of the environment. Aiming at the problem of synchronous positioning and mapping, the Lazy Decision algorithm is improved to improve the loop quality and reduce the amount of calculation. In view of the problems in robot path planning, the prediction distance is introduced into the A* algorithm, and the h(n) weight coefficient in the dynamic weighing heuristic A* algorithm is set to solve the problem of using A* algorithm to expand the number of nodes and easily fall into local optimal problem, while correcting the corners in the path planning, effectively reducing the path planning time by 14%. The effectiveness of the method is verified on an autonomous mobile robot system experimental platform composed of a moving chassis, 2D LIDAR sensors and a computer computing platform. The method not only shortens the running time, optimizes the path complexity, and effectively overcomes disadvantages of a large turning angle and multiple turning angles of traditional path planning methods.
2022, 41(5): 801-807.
doi: 10.13433/j.cnki.1003-8728.20200392
Abstract:
Composite lightweight sandwich structures are widely used in aerospace because of their excellent mechanical properties. Based on the microstructure of the cross section of Protaetia orentalis's elytra, one bio-inspired light sandwich structure with high toughness was designed according to the characteristics of the fibres arrangement and microstructure in elytra. The three-point bending mechanical properties of bionic double-helix laminate and bionic sandwich structure are studied with finite element method, and the fracture toughness was investigated and evaluated. The compression performance of sandwich structure is further analyzed. The results show that bionic sandwich structures have better toughness and the capacity of bearing comparing with the honeycomb sandwich structure. Moreover, the present study has certain reference and guiding significance for designing new composites with high strength and fracture toughness.
Composite lightweight sandwich structures are widely used in aerospace because of their excellent mechanical properties. Based on the microstructure of the cross section of Protaetia orentalis's elytra, one bio-inspired light sandwich structure with high toughness was designed according to the characteristics of the fibres arrangement and microstructure in elytra. The three-point bending mechanical properties of bionic double-helix laminate and bionic sandwich structure are studied with finite element method, and the fracture toughness was investigated and evaluated. The compression performance of sandwich structure is further analyzed. The results show that bionic sandwich structures have better toughness and the capacity of bearing comparing with the honeycomb sandwich structure. Moreover, the present study has certain reference and guiding significance for designing new composites with high strength and fracture toughness.
2022, 41(5): 808-814.
doi: 10.13433/j.cnki.1003-8728.20220069
Abstract:
In order to reveal the multi-scale characteristics of the magnetic signal in tension of carbon steel specimens, 45 steel specimens were selected to carry out quasi-static tensile experiments, and the multi-scale entropy characteristics of the normal component Hp(y) and the magnetic field intensity gradient K in the magnetic field were extracted. Combining the above features, the support vector machine method was selected to construct a damage assessment model. The magnetic domain morphology at each tensile damage stage was observed by atomic force microscopy, and the phase angle characteristics of the magnetic domain were extracted. Results show that there exists a zero point corresponding to the hidden damage area of Hp(y) at each tensile damage stage. As the damage degree increases, the absolute value of Hp(y) increases, and the K value curve has a peak at the zero point of Hp(y). The multi-scale entropy of Hp(y) at each stage increases with the increasing of scale factor. As the damage degree increases, the Hp(y) multi-scale entropy value decreases, while the phase value of the magnetic domain increases. The Hp(y) multi-scale entropy value increases again in the necking and fracture stage, and the phase value of the magnetic domain begins to decrease. The damage recognition accuracy of the damage assessment model is 83.3%. The results can provide method and model support for the in-service inspection and damage assessment of ferromagnetic components.
In order to reveal the multi-scale characteristics of the magnetic signal in tension of carbon steel specimens, 45 steel specimens were selected to carry out quasi-static tensile experiments, and the multi-scale entropy characteristics of the normal component Hp(y) and the magnetic field intensity gradient K in the magnetic field were extracted. Combining the above features, the support vector machine method was selected to construct a damage assessment model. The magnetic domain morphology at each tensile damage stage was observed by atomic force microscopy, and the phase angle characteristics of the magnetic domain were extracted. Results show that there exists a zero point corresponding to the hidden damage area of Hp(y) at each tensile damage stage. As the damage degree increases, the absolute value of Hp(y) increases, and the K value curve has a peak at the zero point of Hp(y). The multi-scale entropy of Hp(y) at each stage increases with the increasing of scale factor. As the damage degree increases, the Hp(y) multi-scale entropy value decreases, while the phase value of the magnetic domain increases. The Hp(y) multi-scale entropy value increases again in the necking and fracture stage, and the phase value of the magnetic domain begins to decrease. The damage recognition accuracy of the damage assessment model is 83.3%. The results can provide method and model support for the in-service inspection and damage assessment of ferromagnetic components.
2022, 41(5): 815-820.
doi: 10.13433/j.cnki.1003-8728.20200420
Abstract:
In order to effectively improve the efficiency of composite main bearing structure, it is of great significance to study the bearing capacity of composite laminated structures with variable thickness. In this paper, based on the continuum shell element of ABAQUS, the shear buckling and post buckling capacity of two variable thickness composite stiffened panels with different stringer cross-sectional areas are calculated by using eigenvalue method and progressive damage failure method. The results show that the relative error between the numerical analysis value and the testing value of buckling load and post buckling load is less than 4%, that is, the model construction and solution method can accurately predict the buckling load and post buckling load; the shear load bearing capacity of stiffened panel is determined by the skin, and the buckling load and post buckling load cannot be effectively improved by changing the cross-sectional area of the stringer.
In order to effectively improve the efficiency of composite main bearing structure, it is of great significance to study the bearing capacity of composite laminated structures with variable thickness. In this paper, based on the continuum shell element of ABAQUS, the shear buckling and post buckling capacity of two variable thickness composite stiffened panels with different stringer cross-sectional areas are calculated by using eigenvalue method and progressive damage failure method. The results show that the relative error between the numerical analysis value and the testing value of buckling load and post buckling load is less than 4%, that is, the model construction and solution method can accurately predict the buckling load and post buckling load; the shear load bearing capacity of stiffened panel is determined by the skin, and the buckling load and post buckling load cannot be effectively improved by changing the cross-sectional area of the stringer.
