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RSS2012 Vol. 31, No. 2
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2012, 31(2): 173-177.
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Abstract:
A theoretical model of temperature for Si3N4 ceramics during micro-detonation of arc strike machining was established,further clarifying the machining mechanism of this new machining technique.Based on finite element method,the temperature of Si3N4 ceramics during micro-detonation of arc strike machining was simulated with the aid of Patran and Nastran softwares;the width and depth of crater impacted by micro-detonation were calculated,obtaining the influence rule of different machining parameters on the shape of impact crate.The results show that the highest temperature of Si3N4 ceramics is over 12 000 ℃ while the high-temperature zone is quite small.With the increase of pulse duration and electricity,the temperature within the machined zone increases rapidly and the temperature outside the machined zone keeps room temperature.The simulation results provide the governing theory for the prediction of the surface appearance of Si3N4 ceramics、the disclosure of the machining mechanism of micro-detonation of arc strike、the appropriate choice of the machining parameter and so on.The data gained from the simulation is proved to be accordant with the experimental data.
A theoretical model of temperature for Si3N4 ceramics during micro-detonation of arc strike machining was established,further clarifying the machining mechanism of this new machining technique.Based on finite element method,the temperature of Si3N4 ceramics during micro-detonation of arc strike machining was simulated with the aid of Patran and Nastran softwares;the width and depth of crater impacted by micro-detonation were calculated,obtaining the influence rule of different machining parameters on the shape of impact crate.The results show that the highest temperature of Si3N4 ceramics is over 12 000 ℃ while the high-temperature zone is quite small.With the increase of pulse duration and electricity,the temperature within the machined zone increases rapidly and the temperature outside the machined zone keeps room temperature.The simulation results provide the governing theory for the prediction of the surface appearance of Si3N4 ceramics、the disclosure of the machining mechanism of micro-detonation of arc strike、the appropriate choice of the machining parameter and so on.The data gained from the simulation is proved to be accordant with the experimental data.
2012, 31(2): 178-181.
Abstract:
For studying characteristics of total reflection tunnel of elastic wave in solid-liquid doping phononic crystal,the transition matrix method is adopted and the transmissivity of elastic wave is studied when incident angle is greater than full reflection angle.The total reflection tunnel effect is found in the transmission wave.As results,the response curves of total reflection tunnel effect versus incident angle are obtained,the response curves of total reflection tunnel effect versus impurity thickness are obtained and the response curves of total reflection tunnel effect versus period are obtained.
For studying characteristics of total reflection tunnel of elastic wave in solid-liquid doping phononic crystal,the transition matrix method is adopted and the transmissivity of elastic wave is studied when incident angle is greater than full reflection angle.The total reflection tunnel effect is found in the transmission wave.As results,the response curves of total reflection tunnel effect versus incident angle are obtained,the response curves of total reflection tunnel effect versus impurity thickness are obtained and the response curves of total reflection tunnel effect versus period are obtained.
2012, 31(2): 182-185.
Abstract:
Condition Based Maintenance on machine tool was proposed.By analyzing the failure data,the building approach and procedure of the piecewise twofold Weibull proportional hazards models containing the early failure period and random failure period was researched.The maintenance threshold decision model of machine tool was studied with the objective-function of maximize usability.The application of rotary example illuminates the method and the models are correct and the Condition Based Maintenance is in accordance with the status of the machine tools,and it can avoid the phenomena of over-maintenance or lack-maintenance.
Condition Based Maintenance on machine tool was proposed.By analyzing the failure data,the building approach and procedure of the piecewise twofold Weibull proportional hazards models containing the early failure period and random failure period was researched.The maintenance threshold decision model of machine tool was studied with the objective-function of maximize usability.The application of rotary example illuminates the method and the models are correct and the Condition Based Maintenance is in accordance with the status of the machine tools,and it can avoid the phenomena of over-maintenance or lack-maintenance.
2012, 31(2): 186-190.
Abstract:
In the ageing forming of autoclave,one of the most important parameter control is to make the air temperature and mold temperature consistently.In this paper,based on the computational fluid dynamics(CFD) and the classic algorithm of fluid dynamics,the hot air fluid in autoclave is simulated by using a simplified two dimensional model and Fluent software.The effects of blowing-in velocity,length of mold,cut-out size and other factors on the temperature field of creep ageing forming are studied.The calculated results show that the effect of blowing-in velocity on the temperature filed is slight,that of length and cut-out size of mold,is great.
In the ageing forming of autoclave,one of the most important parameter control is to make the air temperature and mold temperature consistently.In this paper,based on the computational fluid dynamics(CFD) and the classic algorithm of fluid dynamics,the hot air fluid in autoclave is simulated by using a simplified two dimensional model and Fluent software.The effects of blowing-in velocity,length of mold,cut-out size and other factors on the temperature field of creep ageing forming are studied.The calculated results show that the effect of blowing-in velocity on the temperature filed is slight,that of length and cut-out size of mold,is great.
2012, 31(2): 191-195.
Abstract:
Pipes of steam generator in nuclear power station are made of C-Mn steel and their design service lifetime is over 40 years.During service,the crack may appear in the joints under cyclic temperature loading and high frequency vibration.In reality,with the temperature changing,components have cyclic plastic deformation and the yield stress of the steel changes too.The monotonic deformation which is beyond L黡ers strain makes the steel harden and the yield stress increases.The influences of yield stress changing on the performance of the steel's very high cycle fatigue(VHCF) after 2 kinds of preloading are investigated in this paper.Experiments are carried out in an ultrasonic fatigue test machine to investigate effect of preload of monotonic tension or low cycle fatigue(LCF) on VHCF.The test results show that monotonic tension(5% deformation) heightens the steel's yield stress and improves the VHCF strength.However,the preload of LCF leads to the yield stress decrease and weakens the performance of VHCF.
Pipes of steam generator in nuclear power station are made of C-Mn steel and their design service lifetime is over 40 years.During service,the crack may appear in the joints under cyclic temperature loading and high frequency vibration.In reality,with the temperature changing,components have cyclic plastic deformation and the yield stress of the steel changes too.The monotonic deformation which is beyond L黡ers strain makes the steel harden and the yield stress increases.The influences of yield stress changing on the performance of the steel's very high cycle fatigue(VHCF) after 2 kinds of preloading are investigated in this paper.Experiments are carried out in an ultrasonic fatigue test machine to investigate effect of preload of monotonic tension or low cycle fatigue(LCF) on VHCF.The test results show that monotonic tension(5% deformation) heightens the steel's yield stress and improves the VHCF strength.However,the preload of LCF leads to the yield stress decrease and weakens the performance of VHCF.
2012, 31(2): 196-200.
Abstract:
As the improvement object for the axial part in the combined compressor,the improvement schemes of turboshaft engine were studied.Based on the minimum modification principle,the calculation method of axial compressor parameters and turbine inlet temperature was improved.For given turboshaft engine,corresponding parameters and performance with the axial compressor ratio was calculated and analyzed.And the effects analysis of the axial compressor efficiency was accomplished.Those results provided foundation to adjust parameters for the improvement schemes.It provided improvement schemes of increasing 10% and 20% shaft power,in which the reference for the improvement development of the certain turboshaft engine were obtained.
As the improvement object for the axial part in the combined compressor,the improvement schemes of turboshaft engine were studied.Based on the minimum modification principle,the calculation method of axial compressor parameters and turbine inlet temperature was improved.For given turboshaft engine,corresponding parameters and performance with the axial compressor ratio was calculated and analyzed.And the effects analysis of the axial compressor efficiency was accomplished.Those results provided foundation to adjust parameters for the improvement schemes.It provided improvement schemes of increasing 10% and 20% shaft power,in which the reference for the improvement development of the certain turboshaft engine were obtained.
2012, 31(2): 201-205.
Abstract:
In this paper,a new method to detect damage modes in the composite laminates using the modal strain energy combining with the neural network is proposed.An improved change ratio of element modal strain energy is chosen as damage index because it is more sensitive to damage compared with original index.A three layers BP neural network model is established to diagnose the damage modes in the composite laminate.The present method is validated using a FEM simulation of composite laminates with different damage modes,in which the stiffness of damaged element is given according to the combined material properties degradation model.The results show that the present method is robust,accurate and highly efficient.
In this paper,a new method to detect damage modes in the composite laminates using the modal strain energy combining with the neural network is proposed.An improved change ratio of element modal strain energy is chosen as damage index because it is more sensitive to damage compared with original index.A three layers BP neural network model is established to diagnose the damage modes in the composite laminate.The present method is validated using a FEM simulation of composite laminates with different damage modes,in which the stiffness of damaged element is given according to the combined material properties degradation model.The results show that the present method is robust,accurate and highly efficient.
2012, 31(2): 206-212.
Abstract:
In our opinion,dissolved gas analysis(DGA) is not sensitive to fault data and insufficient for diagnosis.Therefore we propose a new method for diagnosing the faults of a transformer with the principal component analysis(PCA) and the reconstruction-based contribution(RBC).After the PCA model is built,we use the idea of fault reconstruction to define the RBC statistical indices and apply them to the diagnosis of the faults of a transformer.We analyze the performance of the fault diagnosis method that uses the RBC and perform the fault diagnosis.The example study results show that our fault diagnosis method has the effective fault detection rate of 95% and is somewhat effective for detecting the fault whose DGA content is small and that the fault diagnosis method that uses the RBC is also effective for the diagnosis of faults of a transformer.
In our opinion,dissolved gas analysis(DGA) is not sensitive to fault data and insufficient for diagnosis.Therefore we propose a new method for diagnosing the faults of a transformer with the principal component analysis(PCA) and the reconstruction-based contribution(RBC).After the PCA model is built,we use the idea of fault reconstruction to define the RBC statistical indices and apply them to the diagnosis of the faults of a transformer.We analyze the performance of the fault diagnosis method that uses the RBC and perform the fault diagnosis.The example study results show that our fault diagnosis method has the effective fault detection rate of 95% and is somewhat effective for detecting the fault whose DGA content is small and that the fault diagnosis method that uses the RBC is also effective for the diagnosis of faults of a transformer.
2012, 31(2): 213-218.
Abstract:
We present a method for automatically establishing the model for kinematic analysis of planar mechanism with multiple joints and prismatic pair.With the adjacency matrix of a component,we produce the breadth(or depth) priority generation tree,thus obtaining the basic loops of a kinematic chain(or mechanism).According to these basic loops,a mathematical model for the kinematic analysis is automatically established and solved.The mathematical model links the structural analysis of the kinematic chain with the kinematic analysis of a mechanism in the sense of computational mechanism,thus providing an effective method for a given mechanism's kinematic analysis and automatic modeling and solving and an approach for the structural type optimization of the kinematic synthesis of a mechanism.
We present a method for automatically establishing the model for kinematic analysis of planar mechanism with multiple joints and prismatic pair.With the adjacency matrix of a component,we produce the breadth(or depth) priority generation tree,thus obtaining the basic loops of a kinematic chain(or mechanism).According to these basic loops,a mathematical model for the kinematic analysis is automatically established and solved.The mathematical model links the structural analysis of the kinematic chain with the kinematic analysis of a mechanism in the sense of computational mechanism,thus providing an effective method for a given mechanism's kinematic analysis and automatic modeling and solving and an approach for the structural type optimization of the kinematic synthesis of a mechanism.
2012, 31(2): 219-223.
Abstract:
This paper focuses on the design of horizontal crash testing facility of light aircraft.Firstly,several crash testing methods such as horizontal track ejection,slope down and the pendulum drop have been discussed to determine the project and testing procedure of the crash test.Secondly,the suspension and release facilities have been designed according to the requirement of the validation of aircraft crashworthiness,and the selection and positioning method of the sensors have been discussed as well.Full scale crash testing of a light aircraft has been performaed,and important parameters such as overloading of the occupant and the impact force etc.have been measured.Based on these testing results the crashworthiness of the light aircraft has been validated.
This paper focuses on the design of horizontal crash testing facility of light aircraft.Firstly,several crash testing methods such as horizontal track ejection,slope down and the pendulum drop have been discussed to determine the project and testing procedure of the crash test.Secondly,the suspension and release facilities have been designed according to the requirement of the validation of aircraft crashworthiness,and the selection and positioning method of the sensors have been discussed as well.Full scale crash testing of a light aircraft has been performaed,and important parameters such as overloading of the occupant and the impact force etc.have been measured.Based on these testing results the crashworthiness of the light aircraft has been validated.
2012, 31(2): 224-228.
Abstract:
The feasibility of Belly-flap being developed as a pitch control device for tailless configuration at high subsonic is investigated on a BWB in-body airfoil,using CFD method.The size,location and deflection angle of the flap are studied to detect their effects on the aerodynamic characteristics.The results show that the bubble separation due to the belly-flap can change pressure distribution and shock position on the airfoil.In this way,the load distribution can be improved to bring the pitch-up moment in a wide angle of attack.The optimized geometry parameters of Belly-flap can be applied to tailless configuration design and to improve its lift-drag performance in this paper.
The feasibility of Belly-flap being developed as a pitch control device for tailless configuration at high subsonic is investigated on a BWB in-body airfoil,using CFD method.The size,location and deflection angle of the flap are studied to detect their effects on the aerodynamic characteristics.The results show that the bubble separation due to the belly-flap can change pressure distribution and shock position on the airfoil.In this way,the load distribution can be improved to bring the pitch-up moment in a wide angle of attack.The optimized geometry parameters of Belly-flap can be applied to tailless configuration design and to improve its lift-drag performance in this paper.
2012, 31(2): 229-233.
Abstract:
Considering the contact effect between the components and the preload of hydraulic press,a flowchart of finite element analysis for the hydraulic press is developed.The finite element analysis model of YT27-2400B hydraulic press is established.Laser tracking method is used to measure the deformation of the hydraulic press with normal load in the field.By comparing the result of finite element analyses with the result of field measurement,the finite element specification and model of hydraulic press are verified reasonable.The conclusions have some reference value for the hydraulic press design.
Considering the contact effect between the components and the preload of hydraulic press,a flowchart of finite element analysis for the hydraulic press is developed.The finite element analysis model of YT27-2400B hydraulic press is established.Laser tracking method is used to measure the deformation of the hydraulic press with normal load in the field.By comparing the result of finite element analyses with the result of field measurement,the finite element specification and model of hydraulic press are verified reasonable.The conclusions have some reference value for the hydraulic press design.
2012, 31(2): 234-238.
Abstract:
In this paper the cathode structure design and experimental research in electrochemical machining of cascade channels were carried out.The characteristics of flowing field in electrochemical machining were investigated and the different outlet placements were designed.The flowing fields of cathodes with different structures were simulated by finite element method and the results showed that the tubular structure using multi-line holes and gradual changing pitches could make the flowing field more steadily.The simulation results were verified by experiments.
In this paper the cathode structure design and experimental research in electrochemical machining of cascade channels were carried out.The characteristics of flowing field in electrochemical machining were investigated and the different outlet placements were designed.The flowing fields of cathodes with different structures were simulated by finite element method and the results showed that the tubular structure using multi-line holes and gradual changing pitches could make the flowing field more steadily.The simulation results were verified by experiments.
2012, 31(2): 239-243.
Abstract:
The revolute joint is the most widely-used form of movable connection in mechanical systems.The clearance in revolute joint has an important affection to dynamic behavior of mechanical systems.In order to study this impact,the contact dynamics model is established in this paper,in which a nonlinear equivalent spring-damp model is used to describe the characteristic of the two objects collide.The equation of nonlinear equivalent spring-damp model's natural frequency can be obtained by using the piecewise linearization method.The stiffness,clearance and rotational speed are the key impact factors of natural frequency.The effects of these impact factors on natural frequency are analyzed by using the theoretical analysis and ADAMS's dynamics simulation.Thus this paper provides a direction for the mechanism dynamic optimal design.
The revolute joint is the most widely-used form of movable connection in mechanical systems.The clearance in revolute joint has an important affection to dynamic behavior of mechanical systems.In order to study this impact,the contact dynamics model is established in this paper,in which a nonlinear equivalent spring-damp model is used to describe the characteristic of the two objects collide.The equation of nonlinear equivalent spring-damp model's natural frequency can be obtained by using the piecewise linearization method.The stiffness,clearance and rotational speed are the key impact factors of natural frequency.The effects of these impact factors on natural frequency are analyzed by using the theoretical analysis and ADAMS's dynamics simulation.Thus this paper provides a direction for the mechanism dynamic optimal design.
2012, 31(2): 244-249.
Abstract:
A measurement system of binocular stereo vision that uses the two-axis NC turntable is designed.The multi-view measurement data registration principle and implementation are discussed,and the method for accurate calibration of the two rotational axes of the NC turntable is proposed.The core of this method consists of: 1) more than three circular markers are pasted on the turntable;2) the turntable's axis to be calibrated is made to rotate in a positive direction;3) the circular markers are measured from several positions,thus obtaining the 3D coordinates of the center of the circular markers;4) the position of the axis to be calibrated can be calculated from any two of the coordinate point sets of the center of the circular markers;5) with the redundant constraints of the several positions,the final position of the axis in the world coordinate system is determined,thus further improving the calibration accuracy.The multi-view automatic registration of the object to be measured is implemented though accurately calibrating the two axes of the turntable.Experiments are performed to assess the calibration accuracy with our method;the experimental results show that,the measurement system designed with our method can measure the point cloud on the surface of a product quickly and effectively,and can solve the problem of data loss and the difficulty in controlling the data overlap caused by multiple measurements.
A measurement system of binocular stereo vision that uses the two-axis NC turntable is designed.The multi-view measurement data registration principle and implementation are discussed,and the method for accurate calibration of the two rotational axes of the NC turntable is proposed.The core of this method consists of: 1) more than three circular markers are pasted on the turntable;2) the turntable's axis to be calibrated is made to rotate in a positive direction;3) the circular markers are measured from several positions,thus obtaining the 3D coordinates of the center of the circular markers;4) the position of the axis to be calibrated can be calculated from any two of the coordinate point sets of the center of the circular markers;5) with the redundant constraints of the several positions,the final position of the axis in the world coordinate system is determined,thus further improving the calibration accuracy.The multi-view automatic registration of the object to be measured is implemented though accurately calibrating the two axes of the turntable.Experiments are performed to assess the calibration accuracy with our method;the experimental results show that,the measurement system designed with our method can measure the point cloud on the surface of a product quickly and effectively,and can solve the problem of data loss and the difficulty in controlling the data overlap caused by multiple measurements.
2012, 31(2): 250-254.
Abstract:
This paper analyzes the problems existing in the clamping device of a linear ultrasonic motor,proposes the conditions that a reasonable clamping device should meet,and designs a new device for clamping a V-shape stator by using the three-roller clamping scheme.The mechanical properties of the linear ultrasonic motor are tested and the test results are compared.The comparison results show that our new clamping device significantly increases the linear ultrasonic motor's output force,with its maximum output force increasing from 20 N to 26.8 N.The paper proposes that the speed fluctuation of the linear ultrasonic motor should be used to assess its stability,analyzes the factors that may influence its stability and finally puts forward our method for enhancing its stability.
This paper analyzes the problems existing in the clamping device of a linear ultrasonic motor,proposes the conditions that a reasonable clamping device should meet,and designs a new device for clamping a V-shape stator by using the three-roller clamping scheme.The mechanical properties of the linear ultrasonic motor are tested and the test results are compared.The comparison results show that our new clamping device significantly increases the linear ultrasonic motor's output force,with its maximum output force increasing from 20 N to 26.8 N.The paper proposes that the speed fluctuation of the linear ultrasonic motor should be used to assess its stability,analyzes the factors that may influence its stability and finally puts forward our method for enhancing its stability.
2012, 31(2): 255-259.
Abstract:
In this paper,a variable structure parallel mechanism that moving and fixed platforms are linked with four limps possessing is studied.It is feasible that prismatic pairs are selected as driver in each limp based on choice principle of input.Through integration analysis,the moving platform should be provided with 4 spatial DOFs.The universal joints are used to connect limps to moving and fixed platforms,whereas moving platform may obtain many forms of spatial DOFs for various topological structures.Considering practicability of this class of mechanism,2T2R and 3T1R configurations are deduced by screw theory and adding limp.The positional equation and the Jacobian maxim are built,and singular position is researched in different configurations.Finally the method of avoiding initial and global singularity is proposed in order to provide a guide for path planning algorithm.
In this paper,a variable structure parallel mechanism that moving and fixed platforms are linked with four limps possessing is studied.It is feasible that prismatic pairs are selected as driver in each limp based on choice principle of input.Through integration analysis,the moving platform should be provided with 4 spatial DOFs.The universal joints are used to connect limps to moving and fixed platforms,whereas moving platform may obtain many forms of spatial DOFs for various topological structures.Considering practicability of this class of mechanism,2T2R and 3T1R configurations are deduced by screw theory and adding limp.The positional equation and the Jacobian maxim are built,and singular position is researched in different configurations.Finally the method of avoiding initial and global singularity is proposed in order to provide a guide for path planning algorithm.
2012, 31(2): 260-264.
Abstract:
First-order natural frequency is an important indicator to measure the structural dynamic characteristics and the dynamic characteristics of a grinding machine depend on the natural frequencies of its large parts.In this paper,the hot-fix multi-head milling machine is designed for the surface processing of hot fix rhinestone,and the dynamic characteristic of hot-fix multi-head milling machine has been analyzed.The natural frequencies of great parts such as column and grinder bed were raised by optimizing structures in order to improve the dynamic performance of hot-fix multi-head milling machine,avoiding the resonance phenomenon during its working process.Finally,the model analysis of the hot-fix multi-head milling machine optimized has been conducted and it turn out that the optimization structure is feasible.
First-order natural frequency is an important indicator to measure the structural dynamic characteristics and the dynamic characteristics of a grinding machine depend on the natural frequencies of its large parts.In this paper,the hot-fix multi-head milling machine is designed for the surface processing of hot fix rhinestone,and the dynamic characteristic of hot-fix multi-head milling machine has been analyzed.The natural frequencies of great parts such as column and grinder bed were raised by optimizing structures in order to improve the dynamic performance of hot-fix multi-head milling machine,avoiding the resonance phenomenon during its working process.Finally,the model analysis of the hot-fix multi-head milling machine optimized has been conducted and it turn out that the optimization structure is feasible.
2012, 31(2): 265-269.
Abstract:
In order to reduce the impact of wave to the ship-mounted crane during offshore operation under rough weather conditions and extend its period of work time,a set of heave compensation system was developed for ship-mounted crane.The system simulation model was built by using LMS.AMESim software and its dynamic performances were obtained by simulating four kinds of models respectively,and the parameters of PID controller were automatically optimized by using the optimization toolbox of design exploration.The results indicated that the fluctuation of wire tension force was the least under passive heave compensation model;94% impact of ship heave motion to load was eliminated with dead band compensation for the proportional valve in active-passive heave compensation model;however only 84% without dead band compensation.By using optimal simulation parameters to controller of test equipment,less regulation time and more consistent results were derived.
In order to reduce the impact of wave to the ship-mounted crane during offshore operation under rough weather conditions and extend its period of work time,a set of heave compensation system was developed for ship-mounted crane.The system simulation model was built by using LMS.AMESim software and its dynamic performances were obtained by simulating four kinds of models respectively,and the parameters of PID controller were automatically optimized by using the optimization toolbox of design exploration.The results indicated that the fluctuation of wire tension force was the least under passive heave compensation model;94% impact of ship heave motion to load was eliminated with dead band compensation for the proportional valve in active-passive heave compensation model;however only 84% without dead band compensation.By using optimal simulation parameters to controller of test equipment,less regulation time and more consistent results were derived.
2012, 31(2): 270-273.
Abstract:
According to the characteristics of the open-integrated impeller,a highly efficient multi-axis N/C machining processing technology was proposed.The processing was divided into rough machining and finish machining: the roughing is conducted through processing method of 3+2 axis based on IPW and cavity milling,so that big margins can be removed and uneven distribution of local margins can be solved,while the finishing through resetting the u and v parameter lines of the driving surface,and through controlling the tool-axis vector with the interpolation of the boundary point.The machining practice shows that this processing technology can improve the processing quality and shorten the manufacturing cycle efficiently.
According to the characteristics of the open-integrated impeller,a highly efficient multi-axis N/C machining processing technology was proposed.The processing was divided into rough machining and finish machining: the roughing is conducted through processing method of 3+2 axis based on IPW and cavity milling,so that big margins can be removed and uneven distribution of local margins can be solved,while the finishing through resetting the u and v parameter lines of the driving surface,and through controlling the tool-axis vector with the interpolation of the boundary point.The machining practice shows that this processing technology can improve the processing quality and shorten the manufacturing cycle efficiently.
2012, 31(2): 274-278.
Abstract:
This paper contrapose the fact of serious water shortage and the requirement of Lc lifestyle,on the basis of demand design guiding ideology,a set of no power consumption water saving style system of house unit bathroom were designed.This design breaked the normal method of water saving,achieved no power consumption of using secondary water and excavated the potential profit of house secondary water fully.The detail presentation of design ideas and process of system core were presented,the three-dimensional flow and pressure distribution of flow in system core were simulated using Fluent software,the simulated results show that the system met the design demand,and demonstrated the feasibility and applicability of design.
This paper contrapose the fact of serious water shortage and the requirement of Lc lifestyle,on the basis of demand design guiding ideology,a set of no power consumption water saving style system of house unit bathroom were designed.This design breaked the normal method of water saving,achieved no power consumption of using secondary water and excavated the potential profit of house secondary water fully.The detail presentation of design ideas and process of system core were presented,the three-dimensional flow and pressure distribution of flow in system core were simulated using Fluent software,the simulated results show that the system met the design demand,and demonstrated the feasibility and applicability of design.
2012, 31(2): 279-283.
Abstract:
Excited by alternative current,the piezoelectric patch on the piezoelectric walking mechanism will vibrate and makes the feet of the piezoelectric walking mechanism produce local elliptical motion.In order to analyze the relationship between the frequency of excitation signal and mechanism moving states,such as moving forward,moving backward,left-handed rotation,right-handed rotation,and to control mechanism moving states precisely,a new type of piezoelectric walking mechanism was proposed based on the working principle of structure.Modal analysis and response analysis of the vibration component of mechanism was carried out using finite element analysis software.The analysis of the relationship between vibration modal and moving states explained why the machine moved backward.
Excited by alternative current,the piezoelectric patch on the piezoelectric walking mechanism will vibrate and makes the feet of the piezoelectric walking mechanism produce local elliptical motion.In order to analyze the relationship between the frequency of excitation signal and mechanism moving states,such as moving forward,moving backward,left-handed rotation,right-handed rotation,and to control mechanism moving states precisely,a new type of piezoelectric walking mechanism was proposed based on the working principle of structure.Modal analysis and response analysis of the vibration component of mechanism was carried out using finite element analysis software.The analysis of the relationship between vibration modal and moving states explained why the machine moved backward.
2012, 31(2): 284-290.
Abstract:
The blade of TRT device which was used in a corporation is broken.Static strength and stiffness of the blade was analyzed by the finite element software ANSYS.Natural frequencies and modes of the blade were calculated,and then its dynamic characteristics were analyzed.The natural frequency of blade was tested.The analysis results show that the fracture of the blade was not caused by its insufficient strength and stiffness.There gets a good match between the design value,calculated value and test value of blade's natural frequency.It is proved that the dynamic characteristics design of the blade is all right.The fracture of the blade is not due to one pure resonance and the coupling effect of the abnormal incentive and various vibrations maybe cause the fracture of the blade.
The blade of TRT device which was used in a corporation is broken.Static strength and stiffness of the blade was analyzed by the finite element software ANSYS.Natural frequencies and modes of the blade were calculated,and then its dynamic characteristics were analyzed.The natural frequency of blade was tested.The analysis results show that the fracture of the blade was not caused by its insufficient strength and stiffness.There gets a good match between the design value,calculated value and test value of blade's natural frequency.It is proved that the dynamic characteristics design of the blade is all right.The fracture of the blade is not due to one pure resonance and the coupling effect of the abnormal incentive and various vibrations maybe cause the fracture of the blade.
2012, 31(2): 291-294.
Abstract:
We employ the ANSYS/LS-DYNA nonlinear dynamic analysis software to simulate the dynamic response of the asymmetrical windshield subjected to bird impact and calculate the maximum principal stress,strain and displacement of its internal units,thus obtaining their distribution results.The principal stress at the fringe of the asymmetrical windshield subjected to bird impact is as high as nearly 0.8σmax but lasts only a short time and does not cause any damage to the asymmetrical windshield.This design of asymmetrical windshield does not reduce its critical velocity when it is under bird impact.Besides,the dispersion for the position of bird impact has some effect on the critical velocity of the asymmetrical windshield.
We employ the ANSYS/LS-DYNA nonlinear dynamic analysis software to simulate the dynamic response of the asymmetrical windshield subjected to bird impact and calculate the maximum principal stress,strain and displacement of its internal units,thus obtaining their distribution results.The principal stress at the fringe of the asymmetrical windshield subjected to bird impact is as high as nearly 0.8σmax but lasts only a short time and does not cause any damage to the asymmetrical windshield.This design of asymmetrical windshield does not reduce its critical velocity when it is under bird impact.Besides,the dispersion for the position of bird impact has some effect on the critical velocity of the asymmetrical windshield.
2012, 31(2): 295-299.
Abstract:
In recent years smart materials of magneto-rheological fluid are widely used in various fields.However,few studies focus on the metallurgical equipment driving parts.For a rolling mill roller driving system,the limit torque cylindrical magneticfluid coupling was designed and analyzed in this paper using the permanent magnets as the magnetic source.Based on the principle of permanent magnetic fluid coupling,structural design and method of the optimizing structure parameters were discussed;according to the Bingham model,the momentum equation and torque calculation formula of permanent magnetic fluid coupling were derived for further design of the coupling.
In recent years smart materials of magneto-rheological fluid are widely used in various fields.However,few studies focus on the metallurgical equipment driving parts.For a rolling mill roller driving system,the limit torque cylindrical magneticfluid coupling was designed and analyzed in this paper using the permanent magnets as the magnetic source.Based on the principle of permanent magnetic fluid coupling,structural design and method of the optimizing structure parameters were discussed;according to the Bingham model,the momentum equation and torque calculation formula of permanent magnetic fluid coupling were derived for further design of the coupling.
2012, 31(2): 300-305.
Abstract:
To study the non-linear motion essence of vertical impact damping system,a mechanical model was built and studied theoretically.The analytical solution of system dynamical response was gained using transfer function combining with the neighboring boundary compatibility conditions of the system in the fact of its piecewise linear characteristics.Numerical simulation was also performed,taking the experimental parameters of reference literature [1] as input of simulation program,and achieved the conclusion that external exciting frequency is the main factor of affecting the non-linear characteristics of the system.The comparison between the results of simulation and experiments was made which verified the correctness and feasibility of theoretical calculation.
To study the non-linear motion essence of vertical impact damping system,a mechanical model was built and studied theoretically.The analytical solution of system dynamical response was gained using transfer function combining with the neighboring boundary compatibility conditions of the system in the fact of its piecewise linear characteristics.Numerical simulation was also performed,taking the experimental parameters of reference literature [1] as input of simulation program,and achieved the conclusion that external exciting frequency is the main factor of affecting the non-linear characteristics of the system.The comparison between the results of simulation and experiments was made which verified the correctness and feasibility of theoretical calculation.
2012, 31(2): 306-309,316.
Abstract:
Based on the nonlinear kinematic hardening model and isotropic hardening model proposed by Lemaitre and Chaboche,a new term is added in the plastic strain dependent terms.The constitutive equations of the mixed nonlinear hardening(M-NH) model are derived at the complicated loading using Mises' yield function.The efficient implicit backward Euler scheme with radial return is used to obtain strain and stress increments.The least-square error approach is adopted to get material parameters using a finite set of points in the uniaxial stress-strain curve.M-NH model is fulfilled with Fortran codes in order to get backstress and elasto-plastic stiffness matrix.The behavior of the present model constants is analyzed against different conditions.Those individual importance and contribution to stress-strain curve is highlighted.The comparisons between the present results and that of experiment by Chaboche show that it is in better agreement with those results of Chaboche 1991 and Basu Voyiadjis.
Based on the nonlinear kinematic hardening model and isotropic hardening model proposed by Lemaitre and Chaboche,a new term is added in the plastic strain dependent terms.The constitutive equations of the mixed nonlinear hardening(M-NH) model are derived at the complicated loading using Mises' yield function.The efficient implicit backward Euler scheme with radial return is used to obtain strain and stress increments.The least-square error approach is adopted to get material parameters using a finite set of points in the uniaxial stress-strain curve.M-NH model is fulfilled with Fortran codes in order to get backstress and elasto-plastic stiffness matrix.The behavior of the present model constants is analyzed against different conditions.Those individual importance and contribution to stress-strain curve is highlighted.The comparisons between the present results and that of experiment by Chaboche show that it is in better agreement with those results of Chaboche 1991 and Basu Voyiadjis.
2012, 31(2): 310-316.
Abstract:
In this paper,a dynamic model of cracked rotor coupled with rubbing is established.In the model,the rotor shaft is considered as equisection Euler beam,which is supported on bearing at both ends.The nonlinear dynamic responses are obtained by using numerical integral method with modal truncation.The nonlinear dynamic behaviors of the crack-rubbing coupling system are analyzed using the time waveforms,the orbits,frequency spectra,Poincare map and bifurcation plot.Finally,rubbing-crack coupling faults experiments are conducted on ZT-3 type test rig and the results verify the correctness of this new dynamic model.
In this paper,a dynamic model of cracked rotor coupled with rubbing is established.In the model,the rotor shaft is considered as equisection Euler beam,which is supported on bearing at both ends.The nonlinear dynamic responses are obtained by using numerical integral method with modal truncation.The nonlinear dynamic behaviors of the crack-rubbing coupling system are analyzed using the time waveforms,the orbits,frequency spectra,Poincare map and bifurcation plot.Finally,rubbing-crack coupling faults experiments are conducted on ZT-3 type test rig and the results verify the correctness of this new dynamic model.
2012, 31(2): 317-322,329.
Abstract:
The working principles of a new kind of retainer-roller-eccentric arc type overrunning clutch are presented.The effects of various factors on the clutch's performance are investigated quantitatively;its dynamic characteristics and its key components' strength are simulated with MSC.ADAMS and ANSYS.The simulation results indicate that: 1) the idle angle and transient stress of the roller decrease slightly with the proper increase of coefficients of friction among the roller,inner seat and outer seat;2) the increasing number of rollers significantly enhances the load-bearing capacity of the overrunning clutch;3) the larger the spring force,the smaller the idle angle,indicating that the spring force has little effect on the stress of the roller.The simulation results coincide with the actual working of the overrunning clutch.
The working principles of a new kind of retainer-roller-eccentric arc type overrunning clutch are presented.The effects of various factors on the clutch's performance are investigated quantitatively;its dynamic characteristics and its key components' strength are simulated with MSC.ADAMS and ANSYS.The simulation results indicate that: 1) the idle angle and transient stress of the roller decrease slightly with the proper increase of coefficients of friction among the roller,inner seat and outer seat;2) the increasing number of rollers significantly enhances the load-bearing capacity of the overrunning clutch;3) the larger the spring force,the smaller the idle angle,indicating that the spring force has little effect on the stress of the roller.The simulation results coincide with the actual working of the overrunning clutch.
2012, 31(2): 323-329.
Abstract:
A process modeling method was raised based on the cooperative pattern in airplane design,aiming at the difficulty of complexity and enormous magnitude of airplane design process.Investigating design steps,tools and organization of airplane design experienced,3 cooperative patterns were summarized.Characteristics of each pattern were revealed in its application scene.Modeling method separates knowledge requirement of airplane and modeling with cooperative connection net.The net was built by linking design objects and cooperative activities of some patterns.Petri net analysis was introduced to find iterating portions in the net.Simplifying the net with folding iterating portions,leads to a skeleton of design process.Process model was built by adding incidental information to the skeleton.With a use case,the method was proven to be more objective and convenient.
A process modeling method was raised based on the cooperative pattern in airplane design,aiming at the difficulty of complexity and enormous magnitude of airplane design process.Investigating design steps,tools and organization of airplane design experienced,3 cooperative patterns were summarized.Characteristics of each pattern were revealed in its application scene.Modeling method separates knowledge requirement of airplane and modeling with cooperative connection net.The net was built by linking design objects and cooperative activities of some patterns.Petri net analysis was introduced to find iterating portions in the net.Simplifying the net with folding iterating portions,leads to a skeleton of design process.Process model was built by adding incidental information to the skeleton.With a use case,the method was proven to be more objective and convenient.
2012, 31(2): 330-334,339.
Abstract:
In the paper,we describe the multibody system consist of cantilever beam and rotating beam base on two different methods.One is hybird coordinate method which takes the rigid-flexible coupled into account.The other is traditional Kineto-Elasto-Dynamic(KED) method.The dynamic calibration matrix is derive in time domain by introducing chebyshev polynominal to identify the concentrated dynamic load exerted on the rotating beam.The identification results are compare base on different modeling methods through a simulation example.We can analyse the limitation of this identificaion way for nonlinear system and the effect of rigid-flexible coupling on the load identification caused by nonlinear factors.And we propose a new method to remove the response caused by driving moment to improve the identification accuracy.
In the paper,we describe the multibody system consist of cantilever beam and rotating beam base on two different methods.One is hybird coordinate method which takes the rigid-flexible coupled into account.The other is traditional Kineto-Elasto-Dynamic(KED) method.The dynamic calibration matrix is derive in time domain by introducing chebyshev polynominal to identify the concentrated dynamic load exerted on the rotating beam.The identification results are compare base on different modeling methods through a simulation example.We can analyse the limitation of this identificaion way for nonlinear system and the effect of rigid-flexible coupling on the load identification caused by nonlinear factors.And we propose a new method to remove the response caused by driving moment to improve the identification accuracy.
2012, 31(2): 335-339.
Abstract:
Aiming at the problem of difficult to diagnose local defects of aero-engine intershaft bearing,a new diagnosis approach of sideband difference diagnostics of local defects for aero-engine intershaft bearing was proposed in this paper.Based on operating characteristic of intershaft bearing for both inner and outer ring rotation,the approach used signal modulation frequency sideband as the main fault information,and established a complete set of fault diagnosis procedure.Experiments of an aero-engine inter bearing with the outer ring failure were carried out.Using the proposed approach,the local defects of the bearing was judged accurately.The theoretical analysis and fault bearing diagnosis example showed that the method can identify local defects of intershaft bearing and is effective in local defects diagnosis for the aero-engine intershaft bearing
Aiming at the problem of difficult to diagnose local defects of aero-engine intershaft bearing,a new diagnosis approach of sideband difference diagnostics of local defects for aero-engine intershaft bearing was proposed in this paper.Based on operating characteristic of intershaft bearing for both inner and outer ring rotation,the approach used signal modulation frequency sideband as the main fault information,and established a complete set of fault diagnosis procedure.Experiments of an aero-engine inter bearing with the outer ring failure were carried out.Using the proposed approach,the local defects of the bearing was judged accurately.The theoretical analysis and fault bearing diagnosis example showed that the method can identify local defects of intershaft bearing and is effective in local defects diagnosis for the aero-engine intershaft bearing
2012, 31(2): 340-344.
Abstract:
To acquire the responses of airborne vehicle and test the performance of airbag system,finite element models of hull and airbag system for airdrop were established.The penalty function method and Johnson Cook material constitutive model were used in numerical simulation of landing cushion process.The comparison between simulation results and experiment data was carried out,and the error of maximum hull acceleration is smaller than 5%.Thus,the accuracy of simulation model was verified.Under normal airdrop mode and worse airdrop mode,the deceleration data and stress distribution were also obtained by simulation.The results demonstrated that the structural strength of airborne vehicle and the performance of airbag system meet the demand of airdrop.
To acquire the responses of airborne vehicle and test the performance of airbag system,finite element models of hull and airbag system for airdrop were established.The penalty function method and Johnson Cook material constitutive model were used in numerical simulation of landing cushion process.The comparison between simulation results and experiment data was carried out,and the error of maximum hull acceleration is smaller than 5%.Thus,the accuracy of simulation model was verified.Under normal airdrop mode and worse airdrop mode,the deceleration data and stress distribution were also obtained by simulation.The results demonstrated that the structural strength of airborne vehicle and the performance of airbag system meet the demand of airdrop.
