Author Center
Editor Work
Peer Review
Editorial Entry
Email Alert
RSS2019 Vol. 38, No. 1
Display Method:
2019, 38(1): 1-6.
doi: 10.13433/j.cnki.1003-8728.20180114
PDF 990KB
Abstract:
The orthogonal test is designed to study the influence of the spindle speed, feed speed and tool wear on the depth of surface damages of carbon riber reinforced plastic(CFRP). According to the different cutting mechanisms corresponding to different fiber orientations, the effects of the different fiber orientations on the depth of surface damages of composite materials was analyzed. The results show that the tool wear has the greatest influence on the depth of surface damages, the spindle speed is the greater, and the feed speed is the least. In addition, the depth of surface damages increases with the increasing of tool wear, while it decreases with the increasing of spindle speed and feed speed. It will have obvious depth of surface damages only at the orientations of fiber between 90° and 180°.
The orthogonal test is designed to study the influence of the spindle speed, feed speed and tool wear on the depth of surface damages of carbon riber reinforced plastic(CFRP). According to the different cutting mechanisms corresponding to different fiber orientations, the effects of the different fiber orientations on the depth of surface damages of composite materials was analyzed. The results show that the tool wear has the greatest influence on the depth of surface damages, the spindle speed is the greater, and the feed speed is the least. In addition, the depth of surface damages increases with the increasing of tool wear, while it decreases with the increasing of spindle speed and feed speed. It will have obvious depth of surface damages only at the orientations of fiber between 90° and 180°.
2019, 38(1): 7-14.
doi: 10.13433/j.cnki.1003-8728.20180092
Abstract:
There are many uncertain factors that may result in incomplete diagnostic information of planetary gearboxes, such as sensor failures, communication lags and data discretization, etc. However, the existing methods are not suitable for fault diagnosis. Therefore, a fault diagnosis method of planetary gearboxes based on data-driven valued characteristic multi-granularity model is proposed. Incomplete fault diagnosis information of planetary gearbox is analyzed using data-driven valued characteristic relation. Then, the attribute reduction algorithm based on pessimistic data-driven valued characteristic multi-granularity model is employed to extract fault diagnosis decision rules. Finally, the Naive Bayesian classifier is used to determine planetary gearbox condition. The experimental results demonstrate that this method can accurately determine indiscernibility relation among cases, reduce computational complexity, and enhance fault diagnosis accuracy.
There are many uncertain factors that may result in incomplete diagnostic information of planetary gearboxes, such as sensor failures, communication lags and data discretization, etc. However, the existing methods are not suitable for fault diagnosis. Therefore, a fault diagnosis method of planetary gearboxes based on data-driven valued characteristic multi-granularity model is proposed. Incomplete fault diagnosis information of planetary gearbox is analyzed using data-driven valued characteristic relation. Then, the attribute reduction algorithm based on pessimistic data-driven valued characteristic multi-granularity model is employed to extract fault diagnosis decision rules. Finally, the Naive Bayesian classifier is used to determine planetary gearbox condition. The experimental results demonstrate that this method can accurately determine indiscernibility relation among cases, reduce computational complexity, and enhance fault diagnosis accuracy.
2019, 38(1): 15-22.
doi: 10.13433/j.cnki.1003-8728.20180100
Abstract:
The existing dynamic equations in an inertial frame are highly coupled and fully nonlinear and therefore are not conducive to controller design. Inspired by autonomous underwater vehicle's (AUV) underwater modeling in non-inertia frame, this paper defines a non-inertial frame that is always aligned with the eel robot. This kinematics model is derived with the Coriolis theorem and are derived with the improved Newton's second law and the moment balance principle. The kinematics model is analytical and can obtain the tangent velocity sub-dynamics directly and be utilized in model-based modern control schemes. Compared with the existing model, the kinematics model established in this paper achieves the purpose of simplifying the model by decoupling orientation angle parameter. A nine-module robot is numerically simulated and the simulation results are compared with those of the existing exact model. It is found that the simplified model and the exact model almost coincide, thus verifying the accuracy of the simplified model.
The existing dynamic equations in an inertial frame are highly coupled and fully nonlinear and therefore are not conducive to controller design. Inspired by autonomous underwater vehicle's (AUV) underwater modeling in non-inertia frame, this paper defines a non-inertial frame that is always aligned with the eel robot. This kinematics model is derived with the Coriolis theorem and are derived with the improved Newton's second law and the moment balance principle. The kinematics model is analytical and can obtain the tangent velocity sub-dynamics directly and be utilized in model-based modern control schemes. Compared with the existing model, the kinematics model established in this paper achieves the purpose of simplifying the model by decoupling orientation angle parameter. A nine-module robot is numerically simulated and the simulation results are compared with those of the existing exact model. It is found that the simplified model and the exact model almost coincide, thus verifying the accuracy of the simplified model.
2019, 38(1): 23-29.
doi: 10.13433/j.cnki.1003-8728.20180102
Abstract:
The structure of damping groove of rotating-sleeve distributing-flow system has important influence on flow pulsation, pressure pulsation, working noise and operation life. Considering the constraint of flow backward, a structural optimization model of U-shaped damping groove was set up to get the minimized extreme pressure based on the design variables of its thickness, height and angle. It has completed that the structural optimization with sensitivity analysis of design variables to optimization goal using iSIGHT optimal design framework. After optimization, the volumetric efficiency of the pump is basically unchanged, and the extreme pressure of pump chamber is reduced by 8.3%, which significantly reduces the impact and oscillation caused by the pressure overshoot. The optimization design also improves the stability of whole distribution system. The optimization result has strong stability, but the U-shaped damping groove needs to be re-optimized when the rated working speed is higher.
The structure of damping groove of rotating-sleeve distributing-flow system has important influence on flow pulsation, pressure pulsation, working noise and operation life. Considering the constraint of flow backward, a structural optimization model of U-shaped damping groove was set up to get the minimized extreme pressure based on the design variables of its thickness, height and angle. It has completed that the structural optimization with sensitivity analysis of design variables to optimization goal using iSIGHT optimal design framework. After optimization, the volumetric efficiency of the pump is basically unchanged, and the extreme pressure of pump chamber is reduced by 8.3%, which significantly reduces the impact and oscillation caused by the pressure overshoot. The optimization design also improves the stability of whole distribution system. The optimization result has strong stability, but the U-shaped damping groove needs to be re-optimized when the rated working speed is higher.
2019, 38(1): 30-36.
doi: 10.13433/j.cnki.1003-8728.20180104
Abstract:
The special nonlinear stiffness characteristic of canted coil springs is the key to be widely used in high voltage power connection and high performance sealing equipment. In this paper, the theoretical method for calculating the stiffness of canted coil springs was established with the parametric modeling idea, taking single canted coil springs as an example. And through the parametric analysis of the structure of canted coil springs, the influence of each parameter on the structural stiffness was obtained. The present method for calculating the stiffness of canted coil springs is more efficient than the finite element method, and is of great significance in deepening the cognition of the nonlinear mechanism of canted coil springs, thus providing a theoretical guidance for the optimization design, production and testing of canted coil springs.
The special nonlinear stiffness characteristic of canted coil springs is the key to be widely used in high voltage power connection and high performance sealing equipment. In this paper, the theoretical method for calculating the stiffness of canted coil springs was established with the parametric modeling idea, taking single canted coil springs as an example. And through the parametric analysis of the structure of canted coil springs, the influence of each parameter on the structural stiffness was obtained. The present method for calculating the stiffness of canted coil springs is more efficient than the finite element method, and is of great significance in deepening the cognition of the nonlinear mechanism of canted coil springs, thus providing a theoretical guidance for the optimization design, production and testing of canted coil springs.
2019, 38(1): 37-43.
doi: 10.13433/j.cnki.1003-8728.20180108
Abstract:
Aiming at the nonlinear dynamic characteristics of turbine bearings in aircraft environment control system, a state feature extracting method for bearings based on EEMD (Ensemble empirical mode decomposition) and fractal dimension from the angle of vibration signal processing is proposed to analyze the bearing fault more accurately. Firstly, vibration signals under different operating conditions, such as normal bearing, inner ring fault, outer ring fault and cage fault, are decomposed by EEMD to filter noise signal and advance signal-to-noise so as to reduce the adverse effect of background noise on fractal. Then correlation dimension of those signals phase is calculated, contrasted and analyzed after space reconstruction. The experimental results show that, the correlation dimension, as nonlinear geometric invariants, can be used as the characteristic quantity of ECS (Environment control system) turbine bearing on running state. Moreover, this method can accurately and effectively identify the running state of the bearing.
Aiming at the nonlinear dynamic characteristics of turbine bearings in aircraft environment control system, a state feature extracting method for bearings based on EEMD (Ensemble empirical mode decomposition) and fractal dimension from the angle of vibration signal processing is proposed to analyze the bearing fault more accurately. Firstly, vibration signals under different operating conditions, such as normal bearing, inner ring fault, outer ring fault and cage fault, are decomposed by EEMD to filter noise signal and advance signal-to-noise so as to reduce the adverse effect of background noise on fractal. Then correlation dimension of those signals phase is calculated, contrasted and analyzed after space reconstruction. The experimental results show that, the correlation dimension, as nonlinear geometric invariants, can be used as the characteristic quantity of ECS (Environment control system) turbine bearing on running state. Moreover, this method can accurately and effectively identify the running state of the bearing.
2019, 38(1): 44-48.
doi: 10.13433/j.cnki.1003-8728.20180142
Abstract:
The shell part of target cartridge controls is a magnesium alloy thin-walled cylinder part. Compared with the turning, the application of turning-milling complex technology has the characteristics of high spindle speed, small cutting force and low cutting temperature, which can effectively reduce the cutting temperature of magnesium alloy material, improve processing efficiency and ensure processing quality. For the turn-milling machining stability analysis and parameters optimization of the target outer, the milling force model considering the variation of the cutting depth and width is established. The dynamic response characteristics of the workpiece on different processing stages and processing positions are analyzed with finite element methods. Combining the frequency response function of the tool point obtained by the modal impact method, a stability prediction model of turn-milling complex machining is established on the XYZ directions. The stability lobe diagrams under different processing stages are obtained by the full discrete method, and the results show that a different processing stage is corresponding to different stability lobe diagram. The processing efficiency can be improved by optimizing the machining parameters under every processing stage.
The shell part of target cartridge controls is a magnesium alloy thin-walled cylinder part. Compared with the turning, the application of turning-milling complex technology has the characteristics of high spindle speed, small cutting force and low cutting temperature, which can effectively reduce the cutting temperature of magnesium alloy material, improve processing efficiency and ensure processing quality. For the turn-milling machining stability analysis and parameters optimization of the target outer, the milling force model considering the variation of the cutting depth and width is established. The dynamic response characteristics of the workpiece on different processing stages and processing positions are analyzed with finite element methods. Combining the frequency response function of the tool point obtained by the modal impact method, a stability prediction model of turn-milling complex machining is established on the XYZ directions. The stability lobe diagrams under different processing stages are obtained by the full discrete method, and the results show that a different processing stage is corresponding to different stability lobe diagram. The processing efficiency can be improved by optimizing the machining parameters under every processing stage.
2019, 38(1): 49-56.
doi: 10.13433/j.cnki.1003-8728.20180145
Abstract:
Aluminum conductor composite core is made of carbon fiber composite core and formed aluminum wire, and the filling rate of the structure type of formed aluminum wire is high. It has different radial force performances compared with round wire. There is not enough research on the influence of filling rate of formed aluminum wire on radial force at present. This paper carried out the finite element simulation of stress states of the conductor clamped by grip jaw and established the structural model of the conductor that has different filling rates with the ABAQUS software. The simulation produces the stress states of the formed aluminum wire and carbon fiber composite core with different filling rates. The simulation results show that when the conductor is clamped with grip jaw in the stress state, the filling rate influences the transfer of the external force of the conductor to the carbon fiber composite core. As the filling rate decreases, the compressive stress of the formed aluminum wire and carbon fiber composite core increases gradually. The research results can be used as a reference for the optimal design of the length of the clamp of grip jaw for 1 660 mm2 aluminum conductor composite core.
Aluminum conductor composite core is made of carbon fiber composite core and formed aluminum wire, and the filling rate of the structure type of formed aluminum wire is high. It has different radial force performances compared with round wire. There is not enough research on the influence of filling rate of formed aluminum wire on radial force at present. This paper carried out the finite element simulation of stress states of the conductor clamped by grip jaw and established the structural model of the conductor that has different filling rates with the ABAQUS software. The simulation produces the stress states of the formed aluminum wire and carbon fiber composite core with different filling rates. The simulation results show that when the conductor is clamped with grip jaw in the stress state, the filling rate influences the transfer of the external force of the conductor to the carbon fiber composite core. As the filling rate decreases, the compressive stress of the formed aluminum wire and carbon fiber composite core increases gradually. The research results can be used as a reference for the optimal design of the length of the clamp of grip jaw for 1 660 mm2 aluminum conductor composite core.
2019, 38(1): 57-66.
doi: 10.13433/j.cnki.1003-8728.20180224
Abstract:
By introducing the interval process model, this paper proposes an uncertain vibration analysis method for bridges subjected to train moving loads to obtain the upper and lower boundary curves of vibration deflection response of the bridges. Each train is modeled as two subsystems of wheel loads of constant intervals, one containing the front wheel section and the other consisting of the rear wheel section. The bridge is simplified to a simply supported beam model, and the interval process model is used to describe the uncertainty of the moving load flow excitation of the train applied to the bridge. By combining the interval process model and the modal superposition vibration analysis theory, the middle function and radius function of deflection response of the bridge can be obtained, based on which the upper and lower boundary functions of the deflection response can be obtained. Finally, the effectiveness of the proposed method is illustrated by investigating several numerical examples.
By introducing the interval process model, this paper proposes an uncertain vibration analysis method for bridges subjected to train moving loads to obtain the upper and lower boundary curves of vibration deflection response of the bridges. Each train is modeled as two subsystems of wheel loads of constant intervals, one containing the front wheel section and the other consisting of the rear wheel section. The bridge is simplified to a simply supported beam model, and the interval process model is used to describe the uncertainty of the moving load flow excitation of the train applied to the bridge. By combining the interval process model and the modal superposition vibration analysis theory, the middle function and radius function of deflection response of the bridge can be obtained, based on which the upper and lower boundary functions of the deflection response can be obtained. Finally, the effectiveness of the proposed method is illustrated by investigating several numerical examples.
2019, 38(1): 67-72.
doi: 10.13433/j.cnki.1003-8728.20180110
Abstract:
Fused silica glass is a kind of optical glass materials commonly used in engineering field. Cup grinding wheel is widely used in surface grinding of hard and brittle materials, considering brittle fracture and impact effect on materials in grinding, the analysis and modeling of the grinding wheel trajectory and removal efficiency are carried out based on the theory of single particle grinding. The single parameter test of fused silica glass materials with multiple parameters is performed to verify the prediction model. The measured values of the grinding force and the surface topography are well in an agreement with the analyzed. The experiments show that the tmodel can be used to predict the grinding force and optimize the grinding parameters.
Fused silica glass is a kind of optical glass materials commonly used in engineering field. Cup grinding wheel is widely used in surface grinding of hard and brittle materials, considering brittle fracture and impact effect on materials in grinding, the analysis and modeling of the grinding wheel trajectory and removal efficiency are carried out based on the theory of single particle grinding. The single parameter test of fused silica glass materials with multiple parameters is performed to verify the prediction model. The measured values of the grinding force and the surface topography are well in an agreement with the analyzed. The experiments show that the tmodel can be used to predict the grinding force and optimize the grinding parameters.
Iterative Learning Modeling Method of Error Compensation for Machining of Aeroengine Thin-wall Blade
2019, 38(1): 73-79.
doi: 10.13433/j.cnki.1003-8728.20180167
Abstract:
The aerospace complex thin-walled part in the CNC milling process, due to the inconsistency of the actual machining results and theoretical dimensions, has caused the existence of machining errors, which will reduce the accuracy of the parts, and then directly affect its performance. Aiming at the synthetic error which is mainly caused by the elastic deformation during the CNC milling processing of aero-engine thin-walled blade, an iterative learning modeling method of error compensation for aero-engine thin-wall blade machining is studied. Based on the elastic deformation theory and Taylor expansion, the error compensation model is established. According to the data after processing, the compensation amount of the next cutting error is calculated and the blade model is reconstructed, and the new NC machining program is generated. Finally, the machining error satisfies the tolerance requirement. By calculating the compensation model through learning algorithm, the number of compensation can be effectively reduced and the compensation processing efficiency can be improved.
The aerospace complex thin-walled part in the CNC milling process, due to the inconsistency of the actual machining results and theoretical dimensions, has caused the existence of machining errors, which will reduce the accuracy of the parts, and then directly affect its performance. Aiming at the synthetic error which is mainly caused by the elastic deformation during the CNC milling processing of aero-engine thin-walled blade, an iterative learning modeling method of error compensation for aero-engine thin-wall blade machining is studied. Based on the elastic deformation theory and Taylor expansion, the error compensation model is established. According to the data after processing, the compensation amount of the next cutting error is calculated and the blade model is reconstructed, and the new NC machining program is generated. Finally, the machining error satisfies the tolerance requirement. By calculating the compensation model through learning algorithm, the number of compensation can be effectively reduced and the compensation processing efficiency can be improved.
2019, 38(1): 80-89.
doi: 10.13433/j.cnki.1003-8728.20180299
Abstract:
To satisfy the requirements for transition from passive scheduling to active scheduling, an active scheduling method based on production trend prediction was proposed. Its real-time model was established first. For manufacturing resources, their combination and production task, for historic information and real time state, for time series process information on production; for the uncertainty feature of production processes, the Bayesian network inference method was adopted, using the state information on production processes as input to infer the production trend and obtain the abnormal production trend as trigger conditions of active scheduling. By extending the Monte-Carlo tree search algorithm and using its sequential decision-making capacity, the initiative scheduling scheme is generated based on production trend prediction, and adaptive manufacturing is realized. Finally, the active scheduling method was applied to the real time production process analysis of aerospace machining job shop scheduling, thus verifying its effectiveness.
To satisfy the requirements for transition from passive scheduling to active scheduling, an active scheduling method based on production trend prediction was proposed. Its real-time model was established first. For manufacturing resources, their combination and production task, for historic information and real time state, for time series process information on production; for the uncertainty feature of production processes, the Bayesian network inference method was adopted, using the state information on production processes as input to infer the production trend and obtain the abnormal production trend as trigger conditions of active scheduling. By extending the Monte-Carlo tree search algorithm and using its sequential decision-making capacity, the initiative scheduling scheme is generated based on production trend prediction, and adaptive manufacturing is realized. Finally, the active scheduling method was applied to the real time production process analysis of aerospace machining job shop scheduling, thus verifying its effectiveness.
2019, 38(1): 90-95.
doi: 10.13433/j.cnki.1003-8728.20180106
Abstract:
In order to explore the thermal effects of thermal distortion of high speed linear feed axis driven by linear motor, on the basis of experiment, an analytical method by a partial least squares linear regression model(PLSR)with forward variable intelligent self selection was proposed and the impact of the effect factors of thermal distortion behavior on linear feed drive axis was analyzed. According to the established feed axis distortion measurement system on the feed axis test platform, it gives the acquisition scheme of the heat distortion of the linear axis and dynamic temperature in heating process and cooling process. Using the cycle mutation genetic algorithm, the paper provides a self inspection method for acquiring the partial least squares regression parameter and gives the specific steps of the analysis method. With the experiments and regression recognition calculation, the feed axis temperature distribution and the rule of the thermal distortion behavior were analyzed. The results show that, the analysis method with variable self screening partial least squares linear, which can effectively filter the multiple correlation of the variables of temperature measurement points and maintains high regression identification accuracy. Compared with all variable PLSR and backward variables screening Bootstrap method, the regression analysis method can further demonstrates the superiority.
In order to explore the thermal effects of thermal distortion of high speed linear feed axis driven by linear motor, on the basis of experiment, an analytical method by a partial least squares linear regression model(PLSR)with forward variable intelligent self selection was proposed and the impact of the effect factors of thermal distortion behavior on linear feed drive axis was analyzed. According to the established feed axis distortion measurement system on the feed axis test platform, it gives the acquisition scheme of the heat distortion of the linear axis and dynamic temperature in heating process and cooling process. Using the cycle mutation genetic algorithm, the paper provides a self inspection method for acquiring the partial least squares regression parameter and gives the specific steps of the analysis method. With the experiments and regression recognition calculation, the feed axis temperature distribution and the rule of the thermal distortion behavior were analyzed. The results show that, the analysis method with variable self screening partial least squares linear, which can effectively filter the multiple correlation of the variables of temperature measurement points and maintains high regression identification accuracy. Compared with all variable PLSR and backward variables screening Bootstrap method, the regression analysis method can further demonstrates the superiority.
2019, 38(1): 96-103.
doi: 10.13433/j.cnki.1003-8728.20180099
Abstract:
A following-up interpolation algorithm for dual-NURBS (Non-uniform rational B-spline) curve was proposed based on precise calculation of interpolation step-length. First, tool-tip and tool-axis NURBS curves are fitted out from the discrete cutter location data for curved surface NC machining, respectively, and after it the follow-up relation model between the two curve interpolation parameters was established. Then, Simpson integral method is used to calculate the total arc length of the curve, and the acceleration/deceleration planning is conducted for interpolation motion. And next, taking tool-tip NURBS curve interpolation parameters as benchmark, and using Simpson method to determine feeding step-length in each interpolation cycle, and the interpolation point coordinates are subsequently gained. The corresponding interpolation parameters of the tool-axis NURBS curve is acquired according to follow-up relationship model, and the tool pose interpolation of the tool-path planning of surface machining is achieved. Simulation experiment shows that compared with the same parameter interpolation method, the follow-up parameters method can obtain more stable isometric effect, which is conducive to real-time control the tool position and posture in the process of interpolation.
A following-up interpolation algorithm for dual-NURBS (Non-uniform rational B-spline) curve was proposed based on precise calculation of interpolation step-length. First, tool-tip and tool-axis NURBS curves are fitted out from the discrete cutter location data for curved surface NC machining, respectively, and after it the follow-up relation model between the two curve interpolation parameters was established. Then, Simpson integral method is used to calculate the total arc length of the curve, and the acceleration/deceleration planning is conducted for interpolation motion. And next, taking tool-tip NURBS curve interpolation parameters as benchmark, and using Simpson method to determine feeding step-length in each interpolation cycle, and the interpolation point coordinates are subsequently gained. The corresponding interpolation parameters of the tool-axis NURBS curve is acquired according to follow-up relationship model, and the tool pose interpolation of the tool-path planning of surface machining is achieved. Simulation experiment shows that compared with the same parameter interpolation method, the follow-up parameters method can obtain more stable isometric effect, which is conducive to real-time control the tool position and posture in the process of interpolation.
2019, 38(1): 104-107.
doi: 10.13433/j.cnki.1003-8728.20180098
Abstract:
In fused deposition modeling system, prototype parts are accumulated and formed with hot extrusion nozzle fuse.However, the problem is that the build time of prototype parts takes longer.Therefore, based on the mechanism of the build time of prototype parts, the calculation method of the build time is drawn in order to solve the above-mentioned problem.In this paper, through the solid cube with different lengths, the calculated build time is compared with the experimental, then the factors affecting the difference in the generated time is analyzed, and finally the relationship between the prototype parts volume and build time is presented so as to provide a reference for prototype parts for shortening the build time.
In fused deposition modeling system, prototype parts are accumulated and formed with hot extrusion nozzle fuse.However, the problem is that the build time of prototype parts takes longer.Therefore, based on the mechanism of the build time of prototype parts, the calculation method of the build time is drawn in order to solve the above-mentioned problem.In this paper, through the solid cube with different lengths, the calculated build time is compared with the experimental, then the factors affecting the difference in the generated time is analyzed, and finally the relationship between the prototype parts volume and build time is presented so as to provide a reference for prototype parts for shortening the build time.
2019, 38(1): 108-114.
doi: 10.13433/j.cnki.1003-8728.20180101
Abstract:
In order to study the dynamics performance of the metro bogie system more systematically and realistically, a multi-flexible dynamic model for Metro bogie, body and track based on the multi-body dynamics was established taking a B-type bogie as an example. The specific contents included the new non-linear air spring dynamics model and the coupling motion method among components, in which the model was loaded by wheel speed drive and wheel-rail contact so as to be more consistent with the reality. With the display dynamics method, the stability index and the dynamic stress under dynamic operation were obtained and compared with the experimental results. The results show that the experimental results are in a good agreement with the simulated. The present modeling is accurate and reliable, which can provide a new idea for studying bogie dynamics.
In order to study the dynamics performance of the metro bogie system more systematically and realistically, a multi-flexible dynamic model for Metro bogie, body and track based on the multi-body dynamics was established taking a B-type bogie as an example. The specific contents included the new non-linear air spring dynamics model and the coupling motion method among components, in which the model was loaded by wheel speed drive and wheel-rail contact so as to be more consistent with the reality. With the display dynamics method, the stability index and the dynamic stress under dynamic operation were obtained and compared with the experimental results. The results show that the experimental results are in a good agreement with the simulated. The present modeling is accurate and reliable, which can provide a new idea for studying bogie dynamics.
2019, 38(1): 115-120.
doi: 10.13433/j.cnki.1003-8728.20180144
Abstract:
In order to verify the applicability of Electro-Mechanical impedance (EMI) technology in the nondestructive testing of composite structures, a damage detection experimental platform was set up, and different conductance conditions were set up to measure the conductance curves of PZT with different damage states. Through the analysis of the conductance curve based on the RMSD, the relationship between the damage degree and the location of damage and the RMSD value is obtained. The greater the damage degree is, the greater the RMSD value of the conductance curve which is measured by PZT and the larger the distance from the damage location to PZT is, and the larger the RMSD value of the conductance curve is. The validity of the application of EMI to carbon fiber reinforced polymer(CFRP) is verified. With the relationship between the damage distance and the RMSD value, a preliminary positioning experiment is carried out and obtains a high precision location fitting curve.
In order to verify the applicability of Electro-Mechanical impedance (EMI) technology in the nondestructive testing of composite structures, a damage detection experimental platform was set up, and different conductance conditions were set up to measure the conductance curves of PZT with different damage states. Through the analysis of the conductance curve based on the RMSD, the relationship between the damage degree and the location of damage and the RMSD value is obtained. The greater the damage degree is, the greater the RMSD value of the conductance curve which is measured by PZT and the larger the distance from the damage location to PZT is, and the larger the RMSD value of the conductance curve is. The validity of the application of EMI to carbon fiber reinforced polymer(CFRP) is verified. With the relationship between the damage distance and the RMSD value, a preliminary positioning experiment is carried out and obtains a high precision location fitting curve.
2019, 38(1): 121-128.
doi: 10.13433/j.cnki.1003-8728.20180103
Abstract:
Based on the elastic buckling theory, the paper discussed the insufficiency of rod elements with Euler buckling criterion while conducting the stability analysis for truss structures. In order to obtain relatively more accurate buckling responses, beam elements were supposed to be adopted in truss modeling. After that, buckling load factors as well as buckling modes could be obtained via eigenvalue buckling analysis. Then, from the point of ground structure method, the paper pointed some solving difficulties and the singularity of truss topology optimization problems under eigenvalue buckling constraints. To handle such problems effectively, the multi-point approximation algorithm combined with genetic algorithm was implemented to optimize both the discrete topology variables and the continuous sizing variables coordinately. In the meantime, several techniques, such as recognition of buckling modes, filtration of buckling on removed bars, temporary deletion of local constraints, were proposed and applied to tackle the solving difficulties and the singularity. At last, the effectiveness of the optimization strategy was verified by numerical examples. Besides, the efficiency of the method was also presented as the optimization could be achieved through relatively small number of structural analysis.
Based on the elastic buckling theory, the paper discussed the insufficiency of rod elements with Euler buckling criterion while conducting the stability analysis for truss structures. In order to obtain relatively more accurate buckling responses, beam elements were supposed to be adopted in truss modeling. After that, buckling load factors as well as buckling modes could be obtained via eigenvalue buckling analysis. Then, from the point of ground structure method, the paper pointed some solving difficulties and the singularity of truss topology optimization problems under eigenvalue buckling constraints. To handle such problems effectively, the multi-point approximation algorithm combined with genetic algorithm was implemented to optimize both the discrete topology variables and the continuous sizing variables coordinately. In the meantime, several techniques, such as recognition of buckling modes, filtration of buckling on removed bars, temporary deletion of local constraints, were proposed and applied to tackle the solving difficulties and the singularity. At last, the effectiveness of the optimization strategy was verified by numerical examples. Besides, the efficiency of the method was also presented as the optimization could be achieved through relatively small number of structural analysis.
2019, 38(1): 129-133.
doi: 10.13433/j.cnki.1003-8728.20180111
Abstract:
A novel and efficient method for adjusting accuracy and designing shape has been developed for the reflective surface of umbrella-shaped space antenna consisting of supporting rib, reflective membrane surface and cable. Firstly, in order to adjust the shape of the reflector surface by adjusting the cable traction technology, the layout of the cable is designed, and the cable force value is optimized and adjusted based on the support vector machine(SVM)surrogate model and genetic algorithm (GA), then the reflective surface error of root mean square (RMS) is reduced to less than 0.6 mm. Secondly, considering the deformation of the rib, the stress distribution of the rib is obtained by the reposition balance method. The initial shape of the rib is obtained by stress release, and the deformmation shape of the rib is maintained to the desired shape.
A novel and efficient method for adjusting accuracy and designing shape has been developed for the reflective surface of umbrella-shaped space antenna consisting of supporting rib, reflective membrane surface and cable. Firstly, in order to adjust the shape of the reflector surface by adjusting the cable traction technology, the layout of the cable is designed, and the cable force value is optimized and adjusted based on the support vector machine(SVM)surrogate model and genetic algorithm (GA), then the reflective surface error of root mean square (RMS) is reduced to less than 0.6 mm. Secondly, considering the deformation of the rib, the stress distribution of the rib is obtained by the reposition balance method. The initial shape of the rib is obtained by stress release, and the deformmation shape of the rib is maintained to the desired shape.
Compilation Methods of Durable Load-spectrum upon Spectral Frequency and Overload Retardation Effect
2019, 38(1): 134-141.
doi: 10.13433/j.cnki.1003-8728.20180143
Abstract:
All sorts of fatigue load-spectrums authorized at home are on behalf of fleets' average usage cases at present, rather than durable load-spectrum. The solution to the problem is necessary and extremely urgent for not only the development of domestic new generation of aircrafts, but also the used flights' longer lifetime. This contribution proposes two kinds of compilation methods of durable load-spectrum, which on account of the summary of the existing load-spectrum compilation methods and the key technology of the load-spectrum processing. One of which is form a more serious durability load-spectrum, carrying out the probability statistics of the load frequency at all levels and increasing the load frequency, based on the spectral frequency of the load-spectrum methods. This a more serious load-spectrum, which in view of the load-spectrum with overload retardation effect, by depressing the high load to a lower load in the load-spectrum, and relaxing its retardation to subsequent small load. This paper draws up the standard load-spectrum and the new durable ones, and compares the two methods, according to the theories of the above-mentioned methods. Proved by the result of experiments, the proposed both methods can achieve the expected serious effect, meeting the demands of the durable load-spectrum.
All sorts of fatigue load-spectrums authorized at home are on behalf of fleets' average usage cases at present, rather than durable load-spectrum. The solution to the problem is necessary and extremely urgent for not only the development of domestic new generation of aircrafts, but also the used flights' longer lifetime. This contribution proposes two kinds of compilation methods of durable load-spectrum, which on account of the summary of the existing load-spectrum compilation methods and the key technology of the load-spectrum processing. One of which is form a more serious durability load-spectrum, carrying out the probability statistics of the load frequency at all levels and increasing the load frequency, based on the spectral frequency of the load-spectrum methods. This a more serious load-spectrum, which in view of the load-spectrum with overload retardation effect, by depressing the high load to a lower load in the load-spectrum, and relaxing its retardation to subsequent small load. This paper draws up the standard load-spectrum and the new durable ones, and compares the two methods, according to the theories of the above-mentioned methods. Proved by the result of experiments, the proposed both methods can achieve the expected serious effect, meeting the demands of the durable load-spectrum.
2019, 38(1): 142-151.
doi: 10.13433/j.cnki.1003-8728.20180109
Abstract:
The 90° elbow pipe is commonly used for pipeline system. However, the traditional one-section bending produces large turbulence in high-pressure flow and high-velocity fluid, which can cause noise and vibration of pipeline structure. This paper takes an elbow pipe as example to study the optimal design of three-section-bending elbow pipe. Firstly, two pipe shape schemes are proposed according to the vortex generation zone and the secondary flow in curved pipe. In order to minimize the mean value of eddy currents at bend and exit sections, the constrained optimization and linear approximation algorithm is adopted to optimize the 4 parameters of the bending pipe that correspond to the three-section elbow bending catheter. The optimization results show that the three-section bending method reduces the eddy current by 6.29%, the maximum velocity of the secondary flow decreases by 51.97%, and that the pressure loss through the bending section decreases by 12.64%. Finally, the influence of the factors such as diameter, pressure and flow velocity on the optimization results are discussed, and the range of the optimal pipe shape parameter is given. The design provides a theoretical basis for the design of bending section and pulse vibration elimination of an engine pipeline.
The 90° elbow pipe is commonly used for pipeline system. However, the traditional one-section bending produces large turbulence in high-pressure flow and high-velocity fluid, which can cause noise and vibration of pipeline structure. This paper takes an elbow pipe as example to study the optimal design of three-section-bending elbow pipe. Firstly, two pipe shape schemes are proposed according to the vortex generation zone and the secondary flow in curved pipe. In order to minimize the mean value of eddy currents at bend and exit sections, the constrained optimization and linear approximation algorithm is adopted to optimize the 4 parameters of the bending pipe that correspond to the three-section elbow bending catheter. The optimization results show that the three-section bending method reduces the eddy current by 6.29%, the maximum velocity of the secondary flow decreases by 51.97%, and that the pressure loss through the bending section decreases by 12.64%. Finally, the influence of the factors such as diameter, pressure and flow velocity on the optimization results are discussed, and the range of the optimal pipe shape parameter is given. The design provides a theoretical basis for the design of bending section and pulse vibration elimination of an engine pipeline.
2019, 38(1): 152-155.
doi: 10.13433/j.cnki.1003-8728.20180112
Abstract:
The dynamic simulation analysis of membrane-beam hybrid structure is a very importantly challenging subject in engineering application. At present, there are some methods which can effectively solve this kind of problems. In this paper, a new method for solving the stiffness coefficient of spring-mass model of thin-membrane structure is developed based on the principle of energy and the least-squares method, and combined with the general multi-body dynamics simulation software ADMAS to realize the dynamic simulation of the rigid-flexible coupling system of the large-scale deployable thin membrane antenna, then the thin-membrane stress is acquired.
The dynamic simulation analysis of membrane-beam hybrid structure is a very importantly challenging subject in engineering application. At present, there are some methods which can effectively solve this kind of problems. In this paper, a new method for solving the stiffness coefficient of spring-mass model of thin-membrane structure is developed based on the principle of energy and the least-squares method, and combined with the general multi-body dynamics simulation software ADMAS to realize the dynamic simulation of the rigid-flexible coupling system of the large-scale deployable thin membrane antenna, then the thin-membrane stress is acquired.
2019, 38(1): 156-164.
doi: 10.13433/j.cnki.1003-8728.20180159
Abstract:
To analyze the influence of unbalanced vibration on aero-engine external pipes, based on the construction of a real pipe model and a simplified model, the paper probed into the vibration characteristics of the long thin-walled pipes fixed at both ends of the engine with the pipe vibration modal experiment method. And a comparison was made between the experimental result and that obtained through the finite element simulation analysis of the pipe model. It proved that the results obtained from the simplified model and the real model were basically the same; the main vibration types were single bending, double bending and triple bending; the inherent frequency differences of the two models accounted for no more than 10%, except that the differences among the first order were considerable because of its adjacency to both ends of the pipe; the experimental results were in line with the simulation ones. The paper concludes that the vibration modal experiment method can be used in the analysis of the vibration characteristic of the components with incomplete material parameters, which will be helpful for the optimization of the pipe structure and actual prediction of its vibration characteristics.
To analyze the influence of unbalanced vibration on aero-engine external pipes, based on the construction of a real pipe model and a simplified model, the paper probed into the vibration characteristics of the long thin-walled pipes fixed at both ends of the engine with the pipe vibration modal experiment method. And a comparison was made between the experimental result and that obtained through the finite element simulation analysis of the pipe model. It proved that the results obtained from the simplified model and the real model were basically the same; the main vibration types were single bending, double bending and triple bending; the inherent frequency differences of the two models accounted for no more than 10%, except that the differences among the first order were considerable because of its adjacency to both ends of the pipe; the experimental results were in line with the simulation ones. The paper concludes that the vibration modal experiment method can be used in the analysis of the vibration characteristic of the components with incomplete material parameters, which will be helpful for the optimization of the pipe structure and actual prediction of its vibration characteristics.
