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RSS2014 Vol. 33, No. 4
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2014, 33(4): 469-473.
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Abstract:
Based on the finite element technology,using the finite element software MSC.NASTRAN,thethree-dimensional model of a large wind tunnel nozzle is established and the dynamic characteristics were explored.The modal analysis and transient responses were analyzed to obtain the dynamic response and dynamic characteris-tics (natural frequency and vibration modal),and then the analysis results are compared and verified by wind tun-nel vibration frequency experiments.The results show that the nozzle modal frequency distribution and dynamiccharacteristics are better,avoiding the main wind tunnel vibration frequency.
Based on the finite element technology,using the finite element software MSC.NASTRAN,thethree-dimensional model of a large wind tunnel nozzle is established and the dynamic characteristics were explored.The modal analysis and transient responses were analyzed to obtain the dynamic response and dynamic characteris-tics (natural frequency and vibration modal),and then the analysis results are compared and verified by wind tun-nel vibration frequency experiments.The results show that the nozzle modal frequency distribution and dynamiccharacteristics are better,avoiding the main wind tunnel vibration frequency.
2014, 33(4): 474-478.
Abstract:
:Considering several common errors of Globoidal cam to impact kinematic accuracy,a mathematical model for globoid cam with error was established. By using the differential method,the motion accuracy influence coefficient of the globoid cam was obtained. The change rule of kinematic accuracy influence coefficient with the change of globoid cam angle was analyzed via example. The analysis result shows that different error factors have different influence coefficient. The Radius error of globoid cam impact Maximumly the motion precision,and the Shaft angle error affect Minimumly the movement precision. Meshing position of the globoidal cam mechanism af-fects the kinematic accuracy instability. The influence coefficient of motion accuracy has a certain relationship with the structure factors of globoid cam.
:Considering several common errors of Globoidal cam to impact kinematic accuracy,a mathematical model for globoid cam with error was established. By using the differential method,the motion accuracy influence coefficient of the globoid cam was obtained. The change rule of kinematic accuracy influence coefficient with the change of globoid cam angle was analyzed via example. The analysis result shows that different error factors have different influence coefficient. The Radius error of globoid cam impact Maximumly the motion precision,and the Shaft angle error affect Minimumly the movement precision. Meshing position of the globoidal cam mechanism af-fects the kinematic accuracy instability. The influence coefficient of motion accuracy has a certain relationship with the structure factors of globoid cam.
2014, 33(4): 479-483.
Abstract:
The characteristics of rotating mechanical systems are importantly affected by load performance of ball bearings,the loads are the key external factors for static and dynamic characteristics of ball bearings. Considering clearance,structural elastic deformation of outer ring,contact relationship between balls and ring races,the multi-body contact dynamics model of ball bearings is established and simulated by ADAMS software with the user subrou-tine of contact force. The rule of static characteristics of ball bearing is studied for different loads. The dynamic contact force between balls and ring races has been calculated. The effect of preload,contact force duo to radial load and combined load,load distribution angle,relative displacements of rings' centers and contact angle are dis-cussed and verified by theoretical calculation.
The characteristics of rotating mechanical systems are importantly affected by load performance of ball bearings,the loads are the key external factors for static and dynamic characteristics of ball bearings. Considering clearance,structural elastic deformation of outer ring,contact relationship between balls and ring races,the multi-body contact dynamics model of ball bearings is established and simulated by ADAMS software with the user subrou-tine of contact force. The rule of static characteristics of ball bearing is studied for different loads. The dynamic contact force between balls and ring races has been calculated. The effect of preload,contact force duo to radial load and combined load,load distribution angle,relative displacements of rings' centers and contact angle are dis-cussed and verified by theoretical calculation.
2014, 33(4): 484-489.
Abstract:
A novel three degrees of freedom spatial parallel robotic mechanism, which consists of a moving platform con-nected with a fixed base by three different limbs,is proposed. Its moving platform has two-translational and one-rotary DOF with respect to the fixed base. Other two new 2T1R parallel mechanisms with higher rotational capability are e-volved when the moving platform is degenerated to an end-effector and the assemble sequence of three limbs is adjusted.The DOF number of the parallel mechanisms is analyzed and computed based on the screw theory. The kinematic equa-tions including position and pose,velocity and acceleration are established. the mechanism is fully-isotropic throughout the entire workspace as the Jacobian matrix is an identity one and its condition number is equal to 1.
A novel three degrees of freedom spatial parallel robotic mechanism, which consists of a moving platform con-nected with a fixed base by three different limbs,is proposed. Its moving platform has two-translational and one-rotary DOF with respect to the fixed base. Other two new 2T1R parallel mechanisms with higher rotational capability are e-volved when the moving platform is degenerated to an end-effector and the assemble sequence of three limbs is adjusted.The DOF number of the parallel mechanisms is analyzed and computed based on the screw theory. The kinematic equa-tions including position and pose,velocity and acceleration are established. the mechanism is fully-isotropic throughout the entire workspace as the Jacobian matrix is an identity one and its condition number is equal to 1.
2014, 33(4): 490-495.
Abstract:
This paper designs a new indoor path planning algorithm for seeing eye robots using the radio frequency identification (RFID)system. Through combination of ultra high frequency (UHF)radio frequency identification system with low radio frequency identification system,the new algorithm realizes accurate positioning for robots.New algorithm also combines the idea of V-graph algorithm positioning with A*,which not only improves the effi-ciency of searching but also guarantees the feasibility of path planning at the same time. The simulation result veri-fies the effectiveness and feasibility of the new path planning algorithm.
This paper designs a new indoor path planning algorithm for seeing eye robots using the radio frequency identification (RFID)system. Through combination of ultra high frequency (UHF)radio frequency identification system with low radio frequency identification system,the new algorithm realizes accurate positioning for robots.New algorithm also combines the idea of V-graph algorithm positioning with A*,which not only improves the effi-ciency of searching but also guarantees the feasibility of path planning at the same time. The simulation result veri-fies the effectiveness and feasibility of the new path planning algorithm.
2014, 33(4): 496-500.
Abstract:
:A novel 4-DOF precision micro-stage was presented,and the static and dynamic characteristics were ana-lyzed. The substitution method was applied to design a decoupling compliant parallel mechanism based on the traditional 4-RRUR parallel mechanism. The ANSYS software was employed for the stiffness and kinematics analysis. The analysis results showed that the proposed state has the decoupled X and Y direction movement,and it can realize the 4-DOF mi-cro-motion. The results of the sensitivity analysis of the mechansm showed that the displacement sensitivity for each di-rection is about 6 μm/μm, and it illustrated the stage is sensitive. The modal analysis of the mechanism was carried out.It can seen that the stage can achieve 4-DOF movement from the mode shapes. The natural frequency was obtained in two cases with and without prestress,and the difference between the two cases is in the range of 17.2%～52.4%,thus it showed the prestress has a great influence on the natural frequency of mechanism.
:A novel 4-DOF precision micro-stage was presented,and the static and dynamic characteristics were ana-lyzed. The substitution method was applied to design a decoupling compliant parallel mechanism based on the traditional 4-RRUR parallel mechanism. The ANSYS software was employed for the stiffness and kinematics analysis. The analysis results showed that the proposed state has the decoupled X and Y direction movement,and it can realize the 4-DOF mi-cro-motion. The results of the sensitivity analysis of the mechansm showed that the displacement sensitivity for each di-rection is about 6 μm/μm, and it illustrated the stage is sensitive. The modal analysis of the mechanism was carried out.It can seen that the stage can achieve 4-DOF movement from the mode shapes. The natural frequency was obtained in two cases with and without prestress,and the difference between the two cases is in the range of 17.2%～52.4%,thus it showed the prestress has a great influence on the natural frequency of mechanism.
2014, 33(4): 501-505.
Abstract:
Subminiature accessory is an important part of precision machine. The positioning plays an important role in mini-system. A method for positioning subminiature accessory is presented based on the V-fork and air damping. The V-fork can position subminiature accessory roughly,andthe damping can position subminiature ac-cessory precisely.Then the positioning accuracy is analyzed by using the image processing,and a positioning accu-racy is 40 μm after data processing.The present method can position subminiature accessory quickly,avoid dama-ging subminiature accessory and the present method can be implemented easily with low cost.
Subminiature accessory is an important part of precision machine. The positioning plays an important role in mini-system. A method for positioning subminiature accessory is presented based on the V-fork and air damping. The V-fork can position subminiature accessory roughly,andthe damping can position subminiature ac-cessory precisely.Then the positioning accuracy is analyzed by using the image processing,and a positioning accu-racy is 40 μm after data processing.The present method can position subminiature accessory quickly,avoid dama-ging subminiature accessory and the present method can be implemented easily with low cost.
2014, 33(4): 506-510.
Abstract:
Based on the Hertz contact theory,models of normal contact stiffness and equivalent contact torsional stiffness for a single tooth engagement is established for the cycloid meshing drive. Based on these models,the teeth number that take part in meshing at the same time is calculated by using finite element method,and then the equiv-alent contact torsional stiffness of the whole teeth engagement in the cycloid meshing drive is established. The pro-gram of calculating equivalent contact torsional stiffness of the whole teeth engagement is developed using Matlab software,and the equivalent contact torsional stiffness curves of three tooth modifications are calculated for a numer-ical example.The variation characteristics of each curve under three tooth modifications and the relationship be-tween the curve and cycloid tooth profile are discussed.
Based on the Hertz contact theory,models of normal contact stiffness and equivalent contact torsional stiffness for a single tooth engagement is established for the cycloid meshing drive. Based on these models,the teeth number that take part in meshing at the same time is calculated by using finite element method,and then the equiv-alent contact torsional stiffness of the whole teeth engagement in the cycloid meshing drive is established. The pro-gram of calculating equivalent contact torsional stiffness of the whole teeth engagement is developed using Matlab software,and the equivalent contact torsional stiffness curves of three tooth modifications are calculated for a numer-ical example.The variation characteristics of each curve under three tooth modifications and the relationship be-tween the curve and cycloid tooth profile are discussed.
2014, 33(4): 511-515.
Abstract:
In its laminar flow state,the liquid and solid coupling model of oil film and liquid dynamic and static pressure bearing was solved with the FLEUNT software. The thermal deformation of the bearing was calculated with the ANSYS software based on the finite element method. The analysis results show that,the values of maximum temperature rise and maximum radial thermal deformation of the bearing increase rapidly with the increase of rota-tional speed and eccentricity of the bearing and decrease with the increasing ambient temperature,while the inlet oil pressure of the bearing has little effect on the values. The values of maximal radial thermal deformation of the bearing and the values of its clearance have the same order of magnitude,so the heat distortion is not ignorable in analyzing the bearing.
In its laminar flow state,the liquid and solid coupling model of oil film and liquid dynamic and static pressure bearing was solved with the FLEUNT software. The thermal deformation of the bearing was calculated with the ANSYS software based on the finite element method. The analysis results show that,the values of maximum temperature rise and maximum radial thermal deformation of the bearing increase rapidly with the increase of rota-tional speed and eccentricity of the bearing and decrease with the increasing ambient temperature,while the inlet oil pressure of the bearing has little effect on the values. The values of maximal radial thermal deformation of the bearing and the values of its clearance have the same order of magnitude,so the heat distortion is not ignorable in analyzing the bearing.
2014, 33(4): 516-521.
Abstract:
Traditional feature extraction methods usually exist two shortcomings: discriminate information is lost and the low dimensional sensitive information is hard to obtain when the original high dimension space possesses a larger hyper surface curvature. To solve these problems,D-LLE data set dimensionally reduction method is proposed which based on the Dijkstra and Local Linear Embedding (LLE)for rotor fault feature extracting. This new method is used in original feature space that consists of time domain information and frequency domain information to extract low dimensional sensitive information. Dijkstra algorithm which has the ability of specifically depicted the original feature space and the LLE algorithm has the nature of keeping manifold invariant during the dimensionality reduc-tion. So it can extract sensitive characteristics which reflect the running state of rotor machine effectively. Experi-mental results on the rotor experimental table show that the final features extracted by our proposed method are more suitable for clustering and classification applications.
Traditional feature extraction methods usually exist two shortcomings: discriminate information is lost and the low dimensional sensitive information is hard to obtain when the original high dimension space possesses a larger hyper surface curvature. To solve these problems,D-LLE data set dimensionally reduction method is proposed which based on the Dijkstra and Local Linear Embedding (LLE)for rotor fault feature extracting. This new method is used in original feature space that consists of time domain information and frequency domain information to extract low dimensional sensitive information. Dijkstra algorithm which has the ability of specifically depicted the original feature space and the LLE algorithm has the nature of keeping manifold invariant during the dimensionality reduc-tion. So it can extract sensitive characteristics which reflect the running state of rotor machine effectively. Experi-mental results on the rotor experimental table show that the final features extracted by our proposed method are more suitable for clustering and classification applications.
2014, 33(4): 522-526.
Abstract:
During the complete stamping process simulation of sheet metal forming,initial penetration between sheet metal and tools is frequently caused because of inaccurate positioning for tools which leads to the failure of problem-solving. The initial blank mesh will be projected to die mesh and then be smoothed by mesh smoothing method with sliding constraint surface. It can quickly indicate an approximate configuration of blank in next stage and then an ideal initial positioning for tools can be obtained. With the positioning function of the solver,tools' po-sitioning can be adjusted. In this way,the accurate positioning for tools can be realized and the difficult problem of initial penetration during the complete stamping process is solved. The feasibility of the method in this essay has been proved by complete stamping process simulation of front fender form Hyundai Motor.
During the complete stamping process simulation of sheet metal forming,initial penetration between sheet metal and tools is frequently caused because of inaccurate positioning for tools which leads to the failure of problem-solving. The initial blank mesh will be projected to die mesh and then be smoothed by mesh smoothing method with sliding constraint surface. It can quickly indicate an approximate configuration of blank in next stage and then an ideal initial positioning for tools can be obtained. With the positioning function of the solver,tools' po-sitioning can be adjusted. In this way,the accurate positioning for tools can be realized and the difficult problem of initial penetration during the complete stamping process is solved. The feasibility of the method in this essay has been proved by complete stamping process simulation of front fender form Hyundai Motor.
2014, 33(4): 527-530.
Abstract:
The discrete element model of optical glass and the model of ultra-precision machining process were con-structed by numerical simulation and calibration of mechanical properties.Based on these models,the mir-co-machining process of optical glass was simulated,and the effects of different rake angles,cutting depths and cut-ting speeds on the formation of surface cracks were also analyzed.The result show that both of the surface crack number and maximum depth increase with the increasing of cutting depth, while decrease with the increasing of rake angle.The maximum depth increases with the increasing of cutting speed,and the surface cracks decrease with theincrease of cutting speed.
The discrete element model of optical glass and the model of ultra-precision machining process were con-structed by numerical simulation and calibration of mechanical properties.Based on these models,the mir-co-machining process of optical glass was simulated,and the effects of different rake angles,cutting depths and cut-ting speeds on the formation of surface cracks were also analyzed.The result show that both of the surface crack number and maximum depth increase with the increasing of cutting depth, while decrease with the increasing of rake angle.The maximum depth increases with the increasing of cutting speed,and the surface cracks decrease with theincrease of cutting speed.
2014, 33(4): 531-535.
Abstract:
The stability analysis of Z axis system of large size ultra precision machine tool is very important for ma-chine tool design. Aiming at the subject requirements,Hyperworks analysis software is used to make the stability a-nalysis of Z axis system. According to the design idea,a structural model of the Z axis system is constructed firstly based on the geometric modeling,meshing,loading constraint problems. Secondly,on the basis of the model,dy-namic stability analysis and topology optimization about Z axis system are finished and the result obtained is satis-factory,providing a theoretical basis for the design of this type machine tool.
The stability analysis of Z axis system of large size ultra precision machine tool is very important for ma-chine tool design. Aiming at the subject requirements,Hyperworks analysis software is used to make the stability a-nalysis of Z axis system. According to the design idea,a structural model of the Z axis system is constructed firstly based on the geometric modeling,meshing,loading constraint problems. Secondly,on the basis of the model,dy-namic stability analysis and topology optimization about Z axis system are finished and the result obtained is satis-factory,providing a theoretical basis for the design of this type machine tool.
2014, 33(4): 536-540.
Abstract:
Contraposing the difficulty of finishing inner wall of smaller hole such as spit hole and fuel injection pipe on engine,a new equipment for finishing inner wall of smaller hole is designed,elaborating the mechanism of fin-ishing inner wall of smaller hole. On the basis of analyzing the Influencing factors of material removing rate. And through the experiment verifying the factors of inlet pressure,impressed current intensity (magnetic field intensity) and processing time that influenced the processing efficiency and the final surface roughness of finished smaller hole. The optimal parameters of finishing the smaller hole was summarized,which can be used as a tentative refer-ence in finishing other smaller hole.
Contraposing the difficulty of finishing inner wall of smaller hole such as spit hole and fuel injection pipe on engine,a new equipment for finishing inner wall of smaller hole is designed,elaborating the mechanism of fin-ishing inner wall of smaller hole. On the basis of analyzing the Influencing factors of material removing rate. And through the experiment verifying the factors of inlet pressure,impressed current intensity (magnetic field intensity) and processing time that influenced the processing efficiency and the final surface roughness of finished smaller hole. The optimal parameters of finishing the smaller hole was summarized,which can be used as a tentative refer-ence in finishing other smaller hole.
2014, 33(4): 541-545.
Abstract:
A simulation for the deep drawing process of sheet metal was carried out by using Dynaform,the influ-ence of blank holder force,drawing speed and friction coefficient on the forming speed in the deep drawing process of sheet metal were obtained.The forming speed in the deep drawing process of sheet metal determines the form-ingquality of deep drawing,the blank holder force and the deep drawing speed in the deep drawing process are con-trollable parameters,the friction coefficient can be intervened and controlled,and it's a manifestation of the inter-action of all parameters,the main factors which influence the friction coefficient just have blank holder force,form-ing speed and lubrication except the material.
A simulation for the deep drawing process of sheet metal was carried out by using Dynaform,the influ-ence of blank holder force,drawing speed and friction coefficient on the forming speed in the deep drawing process of sheet metal were obtained.The forming speed in the deep drawing process of sheet metal determines the form-ingquality of deep drawing,the blank holder force and the deep drawing speed in the deep drawing process are con-trollable parameters,the friction coefficient can be intervened and controlled,and it's a manifestation of the inter-action of all parameters,the main factors which influence the friction coefficient just have blank holder force,form-ing speed and lubrication except the material.
2014, 33(4): 546-550.
Abstract:
In the real engineering,complex correlation usually existed among multiple acquired excitation source sig-nals.In order to solve this problem,a new de-correlation method based on the average delay whiting is proposed to de-correlate these signals.In this method,several correlation matrixes with different non-zero delays are averaged based on the theory of joint diagonalization,and then the orthogonal matrix to de-correlate the signals is extracted to achieve the separation of correlated signals.A detailed analysis process is presented by elaborating the basic theory of this method.The analysis of simulated signals and vibration signals of real vehicle shows that this method has satisfied separation result for complex correlated vibration source signals.
In the real engineering,complex correlation usually existed among multiple acquired excitation source sig-nals.In order to solve this problem,a new de-correlation method based on the average delay whiting is proposed to de-correlate these signals.In this method,several correlation matrixes with different non-zero delays are averaged based on the theory of joint diagonalization,and then the orthogonal matrix to de-correlate the signals is extracted to achieve the separation of correlated signals.A detailed analysis process is presented by elaborating the basic theory of this method.The analysis of simulated signals and vibration signals of real vehicle shows that this method has satisfied separation result for complex correlated vibration source signals.
2014, 33(4): 551-554.
Abstract:
Interaction of defects with ultrasonic guided waves in pipelines has been analyzed under the defect reflec-tion and detection theories of ultrasonic guided waves.To identify defects in pipelines,with the application of cir-cumferential piezoelectric transducer array,L(0,2)mode in different frequencies has been excited to investigate the relationship between excitation frequencies,amplitudes of converted modes and defect sizes.Results show that with the same excitation frequency,reflection coefficient of crack is larger than that of corrosion when their defect cross-section areas are equivalent;F(2, 3)mode was found when L(0,2)is interacted with cracks;the piezoelec-tric transducer sharing the same circumferential position with defects can receive highest reflection signal.Theresult in this paper is important for the identification of defects in pipelines by using ultrasonic guided waves.
Interaction of defects with ultrasonic guided waves in pipelines has been analyzed under the defect reflec-tion and detection theories of ultrasonic guided waves.To identify defects in pipelines,with the application of cir-cumferential piezoelectric transducer array,L(0,2)mode in different frequencies has been excited to investigate the relationship between excitation frequencies,amplitudes of converted modes and defect sizes.Results show that with the same excitation frequency,reflection coefficient of crack is larger than that of corrosion when their defect cross-section areas are equivalent;F(2, 3)mode was found when L(0,2)is interacted with cracks;the piezoelec-tric transducer sharing the same circumferential position with defects can receive highest reflection signal.Theresult in this paper is important for the identification of defects in pipelines by using ultrasonic guided waves.
2014, 33(4): 555-558.
Abstract:
Using the finite element method and considering the actual working condition,the system model for cal-culating the rolling mill slider typed universal coupling system was implemented and the dangerous position of the key parts were analyzed and the reason of the flat head fracture was found out. The finite element parametric model for the slider typed universal coupling system was built and optimized on the basis of the equal}trength principle,and high}ost factor of fork head was considered. The optimized stress in the dangerous position of the flat head de-creases 19.21%,the optimal fatigue life of the flat head increases 4. 3 times and the strength of the fork head is al-so enough. The optimal results show that the whole carrying capacity and working life of the slider typed universalcoupling system were improved,so as to realize structural optimization design of the coupling system.
Using the finite element method and considering the actual working condition,the system model for cal-culating the rolling mill slider typed universal coupling system was implemented and the dangerous position of the key parts were analyzed and the reason of the flat head fracture was found out. The finite element parametric model for the slider typed universal coupling system was built and optimized on the basis of the equal}trength principle,and high}ost factor of fork head was considered. The optimized stress in the dangerous position of the flat head de-creases 19.21%,the optimal fatigue life of the flat head increases 4. 3 times and the strength of the fork head is al-so enough. The optimal results show that the whole carrying capacity and working life of the slider typed universalcoupling system were improved,so as to realize structural optimization design of the coupling system.
2014, 33(4): 559-563.
Abstract:
Based on SAE car model and using the computational fluid dynamics numerical simulation method,this paper mainly researched the influence that the different positions of non-smooth surfaces with decorating effect on the aerodynamic characteristics.By decorating pit type non-smooth surface on different positions of the SAE car model (sidepiece,bottom,top,front,rear),calculating air drag coefficient and comparing streamline,velocity vector,and pressure between non-smooth surface and the smooth surface,this paper analyzed the reducing drag mechanism of non-smooth surface and the reasons for the differences.According to the results of analysis,we could reasonably obtain the position of non-smooth decorating surface which can reduce the drag coefficient.
Based on SAE car model and using the computational fluid dynamics numerical simulation method,this paper mainly researched the influence that the different positions of non-smooth surfaces with decorating effect on the aerodynamic characteristics.By decorating pit type non-smooth surface on different positions of the SAE car model (sidepiece,bottom,top,front,rear),calculating air drag coefficient and comparing streamline,velocity vector,and pressure between non-smooth surface and the smooth surface,this paper analyzed the reducing drag mechanism of non-smooth surface and the reasons for the differences.According to the results of analysis,we could reasonably obtain the position of non-smooth decorating surface which can reduce the drag coefficient.
2014, 33(4): 564-572.
Abstract:
A novel extended quality function deployment (QFD)method based on compositional data time series and vector autoregression model was proposed to capture and forecast customers ＇individualized needs during the early stage of auto-body product development. Firstly,traditional QFD model was formulated in terms of analytic hierarchy process (AHP)technique.Secondly,according to the sampled customer importance ratings,the compositional data time series in simplex space was transformed into those in real space,which were forecasted by vector autoregression (VAR)model.Lastly,the validated out-of-sample forecasted time series was transformed back to compositional time series of customers' importance ratings in simplex space,and the priorities of design attributes were calculated se-quentially for guiding and planning the resources allocation in personalized Auto-body development.
A novel extended quality function deployment (QFD)method based on compositional data time series and vector autoregression model was proposed to capture and forecast customers ＇individualized needs during the early stage of auto-body product development. Firstly,traditional QFD model was formulated in terms of analytic hierarchy process (AHP)technique.Secondly,according to the sampled customer importance ratings,the compositional data time series in simplex space was transformed into those in real space,which were forecasted by vector autoregression (VAR)model.Lastly,the validated out-of-sample forecasted time series was transformed back to compositional time series of customers' importance ratings in simplex space,and the priorities of design attributes were calculated se-quentially for guiding and planning the resources allocation in personalized Auto-body development.
2014, 33(4): 573-577.
Abstract:
An electric power steering (EPS)and semi-active suspension (SAS)system simulation model was built by using vehicle system dynamics software CarSim and MATLAB /Simulink.Chassis EPS and SAS system were divided into four modules which was built separated,combined with vehicle system model on CarSim,a complete vehicle model was constructed. Each module of the model was independent for easy to build hardware in the loop system.And easily to study the various parts of the EPS and SAS system effect on vehicle’s handling stability and riding comfortably.Compared with the simulation analysis results on CarSim,showed that the EPS and SAS system simulation model was able to provide steering power and adjust suspension damping force.
An electric power steering (EPS)and semi-active suspension (SAS)system simulation model was built by using vehicle system dynamics software CarSim and MATLAB /Simulink.Chassis EPS and SAS system were divided into four modules which was built separated,combined with vehicle system model on CarSim,a complete vehicle model was constructed. Each module of the model was independent for easy to build hardware in the loop system.And easily to study the various parts of the EPS and SAS system effect on vehicle’s handling stability and riding comfortably.Compared with the simulation analysis results on CarSim,showed that the EPS and SAS system simulation model was able to provide steering power and adjust suspension damping force.
2014, 33(4): 578-582.
Abstract:
The dynamics model of a four-wheel steering vehicle (4WS)was established According to driver model of single point optimal preview,a closed-loop motion simulation program of 4WS on the S-type and runway roads was written,and kinematics and dynamics simulations of active four-wheel steering vehicle with proportional control strategy were carried out.The results show that the handling stability of 4WS at high speeds is superior to that of or-dinary front wheel steering vehicles and the control system has fine dynamic characteristics,and the 4WS vehicle with the proposed control strategy can provide greater transient stability and security.
The dynamics model of a four-wheel steering vehicle (4WS)was established According to driver model of single point optimal preview,a closed-loop motion simulation program of 4WS on the S-type and runway roads was written,and kinematics and dynamics simulations of active four-wheel steering vehicle with proportional control strategy were carried out.The results show that the handling stability of 4WS at high speeds is superior to that of or-dinary front wheel steering vehicles and the control system has fine dynamic characteristics,and the 4WS vehicle with the proposed control strategy can provide greater transient stability and security.
2014, 33(4): 583-587.
Abstract:
The softwares of PRO-E and HyperMesh are used to establish the finite element model of a disc brake.Through calculation,the analysis of strength and modal of the caliper and the brake disc are carried out respective-ly.The analysis results show that both the caliper and the brake disc can meet the strength design requirements.In addition,the brake disc with the natural frequencies of 8th and 9th orders and the caliper with the natural frequen-cy of 4th order are very close. Therefore,there is resonance which causes brake scream.According to the brake squeal,the thickness of brake disc is optimized. The optimization results show that,when the thickness of brake disc is changed,resonance can be avoided and the mode of vibration and its size and eventually the stability of disc brake can be improved.
The softwares of PRO-E and HyperMesh are used to establish the finite element model of a disc brake.Through calculation,the analysis of strength and modal of the caliper and the brake disc are carried out respective-ly.The analysis results show that both the caliper and the brake disc can meet the strength design requirements.In addition,the brake disc with the natural frequencies of 8th and 9th orders and the caliper with the natural frequen-cy of 4th order are very close. Therefore,there is resonance which causes brake scream.According to the brake squeal,the thickness of brake disc is optimized. The optimization results show that,when the thickness of brake disc is changed,resonance can be avoided and the mode of vibration and its size and eventually the stability of disc brake can be improved.
2014, 33(4): 588-591.
Abstract:
A secondary regulation loading system must have the ability to produce stable torque and speed.Howev-er,it is a very complex coupling system and its torque and speed fluctuate very easily.To solve this problem,we analyze the characteristics of the system's hydraulic and mechanical structures and establish the mathematical model of the secondary regulation loading system.We then design a fuzzy decoupling controller and successfully decouple the system's coupling relationship with the diagonal decoupling method. We also design a couple of fuzzy controllers to achieve the high-precision control of the system's speed and torque.Finally,the computer simulation results and their analysis show that the fuzzy decoupling controller can effectively control the output torque and speed of the sec- ondary regulation loading system.
A secondary regulation loading system must have the ability to produce stable torque and speed.Howev-er,it is a very complex coupling system and its torque and speed fluctuate very easily.To solve this problem,we analyze the characteristics of the system's hydraulic and mechanical structures and establish the mathematical model of the secondary regulation loading system.We then design a fuzzy decoupling controller and successfully decouple the system's coupling relationship with the diagonal decoupling method. We also design a couple of fuzzy controllers to achieve the high-precision control of the system's speed and torque.Finally,the computer simulation results and their analysis show that the fuzzy decoupling controller can effectively control the output torque and speed of the sec- ondary regulation loading system.
2014, 33(4): 592-595.
Abstract:
Efficiently establishing a strip profile model will help improve the accuracy of the strip profile and effectively achieve flatness control in rolling process.A prediction model for strip profile based on the extreme learning machine (ELM)was proposed.The method of ELM can not only simplify the parameter selection process,but also can select au-tomatically kernel function according to the training sample value,the manually select is not needed.Further it can im-prove the training speed of model.The prediction of strip profile in the rolling process was performed based on the model training via online measured data of four tandem rolling mills of aluminum strip and was experimentally verified.Contrast to support vector machine (SVM)model prediction,the prediction accuracy of the algorithm can achieve the desired precision values even in the case of a small number of training samples.And it has the same or even higher prediction accuracy.Further it has a rapid convergence characteristic and power generalization ability.
Efficiently establishing a strip profile model will help improve the accuracy of the strip profile and effectively achieve flatness control in rolling process.A prediction model for strip profile based on the extreme learning machine (ELM)was proposed.The method of ELM can not only simplify the parameter selection process,but also can select au-tomatically kernel function according to the training sample value,the manually select is not needed.Further it can im-prove the training speed of model.The prediction of strip profile in the rolling process was performed based on the model training via online measured data of four tandem rolling mills of aluminum strip and was experimentally verified.Contrast to support vector machine (SVM)model prediction,the prediction accuracy of the algorithm can achieve the desired precision values even in the case of a small number of training samples.And it has the same or even higher prediction accuracy.Further it has a rapid convergence characteristic and power generalization ability.
2014, 33(4): 596-600.
Abstract:
The Tensile experiment and finite element analysis of adhesively stiffened composite panels with stiffener runout were performed to discuss the destruction properties of stiffened composite panels.The results showed that there is high stress concentration at the stiffener cutout,which interrupts the load path.The failure was initiated at the edge of the run-out and propagated across the skin-stiffener interface.A fracture mechanical approach to utilize cohesive element is able to qualitatively simulate the initiation and propagation of the debonding of the composite stiffened panels,the result is in good agreement with the experiment.It has been verified that the modified stiffened plate is superior to the reference stiffened plate,and the influence of the geometrical parameter on the carrying ca-pacity of the structure was discussed.
The Tensile experiment and finite element analysis of adhesively stiffened composite panels with stiffener runout were performed to discuss the destruction properties of stiffened composite panels.The results showed that there is high stress concentration at the stiffener cutout,which interrupts the load path.The failure was initiated at the edge of the run-out and propagated across the skin-stiffener interface.A fracture mechanical approach to utilize cohesive element is able to qualitatively simulate the initiation and propagation of the debonding of the composite stiffened panels,the result is in good agreement with the experiment.It has been verified that the modified stiffened plate is superior to the reference stiffened plate,and the influence of the geometrical parameter on the carrying ca-pacity of the structure was discussed.
2014, 33(4): 601-604.
Abstract:
Absorption coefficient is an important parameter of sound-absorbing function for the sound-absorbing ma-terial.A new method to measure sound absorption coefficient is presented in this paper,its main steps include:decorate a microphone nearly in front of the under-testing sound-absorbing material,and measure sound pressure at the location of the microphone while the sound wave randomly rip into the absorption material,and use the Fourier transformer to transform the sound pressure into inverted frequency spectrum;then compare the inverted frequency spectrum of the incident sound pressure to get the reflection coefficient on the surface of the sound absorption,final-ly obtain the sound absorption coefficient of the absorption material.Experiment results for different kinds of sound absorption material indicated that the measurement error of this new measuring method is acceptable within the same frequency compared by the standing wave tube method,which proved the feasibility of this method on absorption coefficient measurement.
Absorption coefficient is an important parameter of sound-absorbing function for the sound-absorbing ma-terial.A new method to measure sound absorption coefficient is presented in this paper,its main steps include:decorate a microphone nearly in front of the under-testing sound-absorbing material,and measure sound pressure at the location of the microphone while the sound wave randomly rip into the absorption material,and use the Fourier transformer to transform the sound pressure into inverted frequency spectrum;then compare the inverted frequency spectrum of the incident sound pressure to get the reflection coefficient on the surface of the sound absorption,final-ly obtain the sound absorption coefficient of the absorption material.Experiment results for different kinds of sound absorption material indicated that the measurement error of this new measuring method is acceptable within the same frequency compared by the standing wave tube method,which proved the feasibility of this method on absorption coefficient measurement.
2014, 33(4): 605-609.
Abstract:
A method for manufacturing high-strength metal honeycomb core is to roll metal foil into honeycomb halfcell structure,and then to cement or weld them into honeycomb core. Based on the characteristics in the roll forming process of honeycomb half-cell structure,the influencing rule of the teeth number of forming rolls on the stress, strain,hape and dimension of molded parts in the roll forming is obtained by using ANSYS / LS-DYNA software. Finite element elastoplastic analysis is applied to design and manufacture theforming rolls. Comparing the simulation with experimental values of forming pieces,the results show that it is effective to protect the defects of traditional honeycomb half-cell structure in the rolling forming by using FEM.
A method for manufacturing high-strength metal honeycomb core is to roll metal foil into honeycomb halfcell structure,and then to cement or weld them into honeycomb core. Based on the characteristics in the roll forming process of honeycomb half-cell structure,the influencing rule of the teeth number of forming rolls on the stress, strain,hape and dimension of molded parts in the roll forming is obtained by using ANSYS / LS-DYNA software. Finite element elastoplastic analysis is applied to design and manufacture theforming rolls. Comparing the simulation with experimental values of forming pieces,the results show that it is effective to protect the defects of traditional honeycomb half-cell structure in the rolling forming by using FEM.
2014, 33(4): 610-613.
Abstract:
To control the riveted joint defects of magnesium alloy sheet in self-pierce riveting(SPR) technology at room temperature,the novel SPR device design is proposed based on Theory of the Solution of Inventive Problems(TRIZ). The technical conflict model between SPR device and laser assisted heating system are constructed,and four recommended principles of invention for solving problems is presented. According to the feasibility of the different inventive principles,a new kind of SPR device with laser assisted heating system is obtained. Finally,the motion simulation analysis is carried out by using UG software. The simulation results show that the new design of laser assisted heating SPR device in the upper and lower limit position is not occur interference,the feasibility and effectivity of SPR device with laser assisted system for magnesium alloy sheet is verified.
To control the riveted joint defects of magnesium alloy sheet in self-pierce riveting(SPR) technology at room temperature,the novel SPR device design is proposed based on Theory of the Solution of Inventive Problems(TRIZ). The technical conflict model between SPR device and laser assisted heating system are constructed,and four recommended principles of invention for solving problems is presented. According to the feasibility of the different inventive principles,a new kind of SPR device with laser assisted heating system is obtained. Finally,the motion simulation analysis is carried out by using UG software. The simulation results show that the new design of laser assisted heating SPR device in the upper and lower limit position is not occur interference,the feasibility and effectivity of SPR device with laser assisted system for magnesium alloy sheet is verified.
2014, 33(4): 614-620.
Abstract:
The combined frequency of high and low pressure rotors occurs when a dual-rotor engine rubs. We cannot distinguish the rub-impact of a high-pressure rotor from that of a low-pressure rotor. This paper uses the simplified dynamics model to discuss the dual-rotor engine's rotor-to-case rub-impact. It holds that the rub-impact force is a rotational force. The theoretical analysis and numerical simulation of three types of three types of rub-impact are carried out. The integer time frequency NΩHand the combined frequency NΩH±ΩLoccur when the high-pressure rotor rubs with its case. The integer time frequency NΩLand the combined frequency NΩL±ΩHoccur when the lowpressure rotor rubs with its case. However,the combined frequency is not as obvious on the rotor as on the case. The experiments on the dual-rotor rub-impact are carried out,and the experimental results and measurement results both verify the correctness of the theoretical analysis and numerical simulation results.
The combined frequency of high and low pressure rotors occurs when a dual-rotor engine rubs. We cannot distinguish the rub-impact of a high-pressure rotor from that of a low-pressure rotor. This paper uses the simplified dynamics model to discuss the dual-rotor engine's rotor-to-case rub-impact. It holds that the rub-impact force is a rotational force. The theoretical analysis and numerical simulation of three types of three types of rub-impact are carried out. The integer time frequency NΩHand the combined frequency NΩH±ΩLoccur when the high-pressure rotor rubs with its case. The integer time frequency NΩLand the combined frequency NΩL±ΩHoccur when the lowpressure rotor rubs with its case. However,the combined frequency is not as obvious on the rotor as on the case. The experiments on the dual-rotor rub-impact are carried out,and the experimental results and measurement results both verify the correctness of the theoretical analysis and numerical simulation results.
2014, 33(4): 621-624.
Abstract:
We present the anti-fatigue design method and believe that the nominal stress fatigue design method suits structural designs in avionics. The finite element analysis of avionics equipment produces its largest acceleration response,whose natural frequency is calculated with the finite element method. According to the natural frequency, the number of the largest response vibration cycles is determined to select the type of nominal stress fatigue design method. The largest endurance vibration stress is calculated. The nominal stress fatigue is used to determine the fatigue life of avionics equipment.
We present the anti-fatigue design method and believe that the nominal stress fatigue design method suits structural designs in avionics. The finite element analysis of avionics equipment produces its largest acceleration response,whose natural frequency is calculated with the finite element method. According to the natural frequency, the number of the largest response vibration cycles is determined to select the type of nominal stress fatigue design method. The largest endurance vibration stress is calculated. The nominal stress fatigue is used to determine the fatigue life of avionics equipment.
