2001 Vol.14(3)
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2001, 15(3).
Abstract:
To understand the deformation and removal mechanism of material on nano-scale and at ultralow loads, a systemic study on AFM micro/nano-machining on single crystal silicon is conducted. The results indicate that AFM nano-machining has a precisely dimensional controllability and a good surface quality on nanometerscale. ASEM is adopted to observe nano-machined region and chips, the results indicate that the material removal mechanisms change with the qpplied normal load. An XPS is used to analyze the changes of chemical composition inside and outside the nano-machined region respectively. The nano-indentation which is conducted with the same AFM diamond tip on the machined region shows a big discrepancy comparedwith that on the macro-scale. The calculated results show higher nano-hardness and elastic modulus than normal values. This phenomenon can be regarded as the indentation size effect (ISE).
To understand the deformation and removal mechanism of material on nano-scale and at ultralow loads, a systemic study on AFM micro/nano-machining on single crystal silicon is conducted. The results indicate that AFM nano-machining has a precisely dimensional controllability and a good surface quality on nanometerscale. ASEM is adopted to observe nano-machined region and chips, the results indicate that the material removal mechanisms change with the qpplied normal load. An XPS is used to analyze the changes of chemical composition inside and outside the nano-machined region respectively. The nano-indentation which is conducted with the same AFM diamond tip on the machined region shows a big discrepancy comparedwith that on the macro-scale. The calculated results show higher nano-hardness and elastic modulus than normal values. This phenomenon can be regarded as the indentation size effect (ISE).
2001, 15(3).
Abstract:
A three-dimensional finite-element simulation of stretching technological parameters of heavy forgings is performed by using ANSYS program. The law of internal stress distribution with different bt/h tool width ratio) and different bb/h(blank width ratio) is studied. Consequently, the critical tool width ratio (bt/h)cr and blank width ratio (bb/h)cr leading no bi-axial tension are botained. It lays a credible foundation for designing reasonable stretching technology.
A three-dimensional finite-element simulation of stretching technological parameters of heavy forgings is performed by using ANSYS program. The law of internal stress distribution with different bt/h tool width ratio) and different bb/h(blank width ratio) is studied. Consequently, the critical tool width ratio (bt/h)cr and blank width ratio (bb/h)cr leading no bi-axial tension are botained. It lays a credible foundation for designing reasonable stretching technology.
2001, 15(3).
Abstract:
Multi-motor vibratory transmission systems have been wide used in large vibratory machines, and four-motor linear vibratory machine is one typical equipment of them. Under non-forcible synchronization condition zero-phase synchronization of the machine is non-stationary and π-phase synchronization is stable. Under half-forcible synchronization condition in which only one motor is controlled being synchronous to another, only lag synchronization near zero-phase synchronization can be realized. Both of the characteristics have never been revealed with classical theory quantitatively. The problemis solved by means of eatablishing an electromechanical coupling mathematical model of the system and unmerical analysis of the starting processes.
Multi-motor vibratory transmission systems have been wide used in large vibratory machines, and four-motor linear vibratory machine is one typical equipment of them. Under non-forcible synchronization condition zero-phase synchronization of the machine is non-stationary and π-phase synchronization is stable. Under half-forcible synchronization condition in which only one motor is controlled being synchronous to another, only lag synchronization near zero-phase synchronization can be realized. Both of the characteristics have never been revealed with classical theory quantitatively. The problemis solved by means of eatablishing an electromechanical coupling mathematical model of the system and unmerical analysis of the starting processes.
2001, 15(3).
Abstract:
Both experiment and simulation are made on the AIMg4.5Mn0.4 sheet blanking with 1%, 10% and 20% relative clearance respectively. The cutting force curves and the cutting surface parameters which can be used to describe the quality of the blankings are measured. Simulation is accomplished by MARC Autoforge software package. Calculated cutting forces are always bigger than mesaured ones. All difference between experiment and simulation is not greater than 20%.It is feasible making virtual experiment on workstation to estimate the cutting force and to predict the quality of the workpiece for new material using certain blanking technical parameters.
Both experiment and simulation are made on the AIMg4.5Mn0.4 sheet blanking with 1%, 10% and 20% relative clearance respectively. The cutting force curves and the cutting surface parameters which can be used to describe the quality of the blankings are measured. Simulation is accomplished by MARC Autoforge software package. Calculated cutting forces are always bigger than mesaured ones. All difference between experiment and simulation is not greater than 20%.It is feasible making virtual experiment on workstation to estimate the cutting force and to predict the quality of the workpiece for new material using certain blanking technical parameters.
2001, 15(3).
Abstract:
Multi-fluid k-ε-kp two phase turbulence model is used to simulate charged gas-liquid two phase coaxial jet ,which is the transorting flow field in electrostatic spraying. Compared with the results of experiment, charged gas-liquid two-phase turbulence can be well predicted by this model.
Multi-fluid k-ε-kp two phase turbulence model is used to simulate charged gas-liquid two phase coaxial jet ,which is the transorting flow field in electrostatic spraying. Compared with the results of experiment, charged gas-liquid two-phase turbulence can be well predicted by this model.
2001, 15(3).
Abstract:
A new method, which is called image manipulation, is introduced to analyze the cavitation of flow field for the first time. As the complexity of the cavitation development must be considering, only the method of image manipulation can calculate the strengt of the cavitation more accurately. This method based on wavelet transform is used to eliminate the noise. The area of the cavitations is deduced to serve as the strength of cavitation. The method is applied in an example of inducer's rotating cavitation. The results show that using image manipulation can get the accurate date of cavitation with ease, and the reason of the inducer shaft's vibration is uncovered clearly.
A new method, which is called image manipulation, is introduced to analyze the cavitation of flow field for the first time. As the complexity of the cavitation development must be considering, only the method of image manipulation can calculate the strengt of the cavitation more accurately. This method based on wavelet transform is used to eliminate the noise. The area of the cavitations is deduced to serve as the strength of cavitation. The method is applied in an example of inducer's rotating cavitation. The results show that using image manipulation can get the accurate date of cavitation with ease, and the reason of the inducer shaft's vibration is uncovered clearly.
2001, 15(3).
Abstract:
A dynamic database based dynamic scheduling system is proposed. As the schedule is being preformed, the scheduling task data in the dynamic database is updated timely. Genetic algorithm (GA) is employed for generating optimized production plan quickly and easily in response to changes on the shop floor. The current status of the shop is considered while rescheduling, and new plan is used in conjunction with the existing schedule to improve the effeciency of flexible manufacturing systems. Simulation results demonstrate the effectiveness of the proposed system.
A dynamic database based dynamic scheduling system is proposed. As the schedule is being preformed, the scheduling task data in the dynamic database is updated timely. Genetic algorithm (GA) is employed for generating optimized production plan quickly and easily in response to changes on the shop floor. The current status of the shop is considered while rescheduling, and new plan is used in conjunction with the existing schedule to improve the effeciency of flexible manufacturing systems. Simulation results demonstrate the effectiveness of the proposed system.
2001, 15(3).
Abstract:
The class of system considered is a single degree of freedom undamped vibrating system with a clearance in which the dynamical behavior is described by a state-space representation in real time. The direct identification technique for the estimate of a clearance and other parameters in the system is presented in terms of least squares method and step-by-step iteration approach. For numerical simulation purpose, the simulated data are achieved by corrupting the modeled responses. The mathematical algorithm, which is put forward, has proven to be effective through a practical numerical example.
The class of system considered is a single degree of freedom undamped vibrating system with a clearance in which the dynamical behavior is described by a state-space representation in real time. The direct identification technique for the estimate of a clearance and other parameters in the system is presented in terms of least squares method and step-by-step iteration approach. For numerical simulation purpose, the simulated data are achieved by corrupting the modeled responses. The mathematical algorithm, which is put forward, has proven to be effective through a practical numerical example.
2001, 15(3).
Abstract:
A general industrial CCD(ICCD)camera is redesigned to detect the weld pool without arc at the period of short circuiting, so that the interference of arc and spatter during CO2 short circuiting arc welding is eliminated. Through the analysis of weld pool image, both size parameters (such as weld pool area A ,weld pool length L1,L2 and weld pool breadth b) and contour parameters(bi which describe the curves of weld pool boundany), which could indicate the shape features of weld pool, had been defined to express weld pool information quantitatively. The investigation of the relationships between weld pool shape parameters and welding process parameters may be beneficial to the quality control of CO2 welding.
A general industrial CCD(ICCD)camera is redesigned to detect the weld pool without arc at the period of short circuiting, so that the interference of arc and spatter during CO2 short circuiting arc welding is eliminated. Through the analysis of weld pool image, both size parameters (such as weld pool area A ,weld pool length L1,L2 and weld pool breadth b) and contour parameters(bi which describe the curves of weld pool boundany), which could indicate the shape features of weld pool, had been defined to express weld pool information quantitatively. The investigation of the relationships between weld pool shape parameters and welding process parameters may be beneficial to the quality control of CO2 welding.
2001, 15(3).
Abstract:
From the point of view of saving energy, a new shift schedule and auto-controlling strategy for automatic transmission are proposed. In order to verify this shift schedule, a simulation program using a software package of Matlab/Simulink is devloped. The simulation results show the shift schedule is correct. This shift schedule has enriched the theory of vehicle automatic maneuvering and will improve the efficiency of hydrodynanic drive system of the vehicle.
From the point of view of saving energy, a new shift schedule and auto-controlling strategy for automatic transmission are proposed. In order to verify this shift schedule, a simulation program using a software package of Matlab/Simulink is devloped. The simulation results show the shift schedule is correct. This shift schedule has enriched the theory of vehicle automatic maneuvering and will improve the efficiency of hydrodynanic drive system of the vehicle.
2001, 15(3).
Abstract:
A component synthesis vibration suppression(CSVS) method for flexible structures is put forward. It can eliminate any unwanted orders of flexible vibration modes while achieves desired rigid motion. This method has robustness to uncertainty of frequency,which makes it practical in engineering. Several time optimal and time-fuel optimal control strategies are designed for a kind of single flexible link. Simulation results validate the feasibility of our method.
A component synthesis vibration suppression(CSVS) method for flexible structures is put forward. It can eliminate any unwanted orders of flexible vibration modes while achieves desired rigid motion. This method has robustness to uncertainty of frequency,which makes it practical in engineering. Several time optimal and time-fuel optimal control strategies are designed for a kind of single flexible link. Simulation results validate the feasibility of our method.
2001, 15(3).
Abstract:
Fast wavelet multi-resolution analysis (wavelet MRA)provides a effective tool for annlyzing and canceling disturbing components in original signal. Because of its exponential frequency axis, the method isn't suitable for extracting harmonic components. The modified exponential time-frequency distribution (MED)overcomes the problems of Wigner distribution(WD),can suppress cross-terms and cancel noise further more.MED provides high resolution in both time and frequency domains, so it can make out weak period impulse components from signal with mighty harmonic components. According to the "time"behavior, together with "frequency"behavior in one figure, the essential structure of a signal is revealed clearly. According to the analysis of algorithm and fault diagnosis example, the joint of wavelet MRA and MED is a powerful tool for fault diagnosis.
Fast wavelet multi-resolution analysis (wavelet MRA)provides a effective tool for annlyzing and canceling disturbing components in original signal. Because of its exponential frequency axis, the method isn't suitable for extracting harmonic components. The modified exponential time-frequency distribution (MED)overcomes the problems of Wigner distribution(WD),can suppress cross-terms and cancel noise further more.MED provides high resolution in both time and frequency domains, so it can make out weak period impulse components from signal with mighty harmonic components. According to the "time"behavior, together with "frequency"behavior in one figure, the essential structure of a signal is revealed clearly. According to the analysis of algorithm and fault diagnosis example, the joint of wavelet MRA and MED is a powerful tool for fault diagnosis.
2001, 15(3).
Abstract:
Directed at how to integrated storage characteristic with on-line service characteristic of AS/RS,a solution based on database design and programming method is proposed. The results show that this model is reasonable and applicable while using in some small or middle enterprises material handling system.
Directed at how to integrated storage characteristic with on-line service characteristic of AS/RS,a solution based on database design and programming method is proposed. The results show that this model is reasonable and applicable while using in some small or middle enterprises material handling system.
2001, 15(3).
Abstract:
To develop cruise control system of an automobile with the metal pushing V-belt type CVT,the dynamic model of automobile travelling longitudinally is estabilished, and the fuzzy controller of control system is designed. Considering uncertainty system parameter and exterior resistance disturbances, the stability of controller is investigated by simulating. The results of its simulation show that the fuzzy controller designed has practicability.
To develop cruise control system of an automobile with the metal pushing V-belt type CVT,the dynamic model of automobile travelling longitudinally is estabilished, and the fuzzy controller of control system is designed. Considering uncertainty system parameter and exterior resistance disturbances, the stability of controller is investigated by simulating. The results of its simulation show that the fuzzy controller designed has practicability.
2001, 15(3).
Abstract:
A method of setting up a pressure-stroke characteristic of the working liquid in hydraulic drawing is studied. A pressure-stroke characteristic and software for controlling its forming process are also developed. And a set of pressure controlling devices with PLC as a central processor are designed. It can be got from the relevant experiments that the pressure-stroke characteristic is correct and its control for forming process is available.
A method of setting up a pressure-stroke characteristic of the working liquid in hydraulic drawing is studied. A pressure-stroke characteristic and software for controlling its forming process are also developed. And a set of pressure controlling devices with PLC as a central processor are designed. It can be got from the relevant experiments that the pressure-stroke characteristic is correct and its control for forming process is available.
2001, 15(3).
Abstract:
Theoretical analyses and experimental studies of the mechanisms of melting film formation are performd. The results show that frictional heating is the dominant mechanism because temperature behaves in the manner predicted by the theory of frictional heating. A study of the active technology for anti-skid is also made. Conclusions indicate that adjusting tire pneumatic pressure can improve the control stability and the travelling safety of an ice-automobile.
Theoretical analyses and experimental studies of the mechanisms of melting film formation are performd. The results show that frictional heating is the dominant mechanism because temperature behaves in the manner predicted by the theory of frictional heating. A study of the active technology for anti-skid is also made. Conclusions indicate that adjusting tire pneumatic pressure can improve the control stability and the travelling safety of an ice-automobile.
2001, 15(3).
Abstract:
It is very common in structural optimization that the optima lie at or in the vicinities of the singular points of feasible domain. Therefore it is very reasonable to introduce wavelet transform that is advantageous in singularity detection. The principle and algorithm of the application of wavelet transform in structural optimization are discussed The feasibility is demonstrated by some typical examples.
It is very common in structural optimization that the optima lie at or in the vicinities of the singular points of feasible domain. Therefore it is very reasonable to introduce wavelet transform that is advantageous in singularity detection. The principle and algorithm of the application of wavelet transform in structural optimization are discussed The feasibility is demonstrated by some typical examples.
2001, 15(3).
Abstract:
The piezothermoelectric actuator/sensor collocation for advanced intelligent structure is studied. The quasi-static equations of piezothermoelasticity are used to analyze the coupling effects between the displacement, temperature and electric fields of piezothermoelasticity continua and the governing equations for piezothermoelectric continua are derived to discuss the dffects of coupling factors on the control/sensing performance in intelligent structure. Based on those analyses, a finite element analysis model of distributed piezothermoelectric continua is developed later. The thermal stress and deformation of a beam are calculated by FEA method so as to determine the optimal actuator/sensor placement. Based on the results of the optimal analysis procedure of actuator/sensor placement, some conclusions of actuator/sensor placement are obtained. Thus, the optimal actuator/sensor placement for piezothermoelectric intelligent structure can be found from the actuator/sensor placements available so that intelligent system will have the best controllability and observability.
The piezothermoelectric actuator/sensor collocation for advanced intelligent structure is studied. The quasi-static equations of piezothermoelasticity are used to analyze the coupling effects between the displacement, temperature and electric fields of piezothermoelasticity continua and the governing equations for piezothermoelectric continua are derived to discuss the dffects of coupling factors on the control/sensing performance in intelligent structure. Based on those analyses, a finite element analysis model of distributed piezothermoelectric continua is developed later. The thermal stress and deformation of a beam are calculated by FEA method so as to determine the optimal actuator/sensor placement. Based on the results of the optimal analysis procedure of actuator/sensor placement, some conclusions of actuator/sensor placement are obtained. Thus, the optimal actuator/sensor placement for piezothermoelectric intelligent structure can be found from the actuator/sensor placements available so that intelligent system will have the best controllability and observability.
2001, 15(3).
Abstract:
The methods of identifying geometric error parameters for NC machine tools are introduced. According to analyzing and comparing the differentmethods, a new method —displacement method with 9 lines is developed based on the theories of the movement errors of multibody system (MBS). A lot of experiments are also made to obtain 21 terms geometric error parameters by using the error identification software based on the new method.
The methods of identifying geometric error parameters for NC machine tools are introduced. According to analyzing and comparing the differentmethods, a new method —displacement method with 9 lines is developed based on the theories of the movement errors of multibody system (MBS). A lot of experiments are also made to obtain 21 terms geometric error parameters by using the error identification software based on the new method.
2001, 15(3).
Abstract:
A universal expression for the transmitted power to the flexible foundation via the finite continuous isolation system of asymmetry is derived where the concept of effective mobility for the coupled system with continuous contact points is put forward. On the basis of the theoretic calculation and analysis, effects of structure parameters of the system on the power flow transmission as well as on the isolation efficiency are fully investigated.
A universal expression for the transmitted power to the flexible foundation via the finite continuous isolation system of asymmetry is derived where the concept of effective mobility for the coupled system with continuous contact points is put forward. On the basis of the theoretic calculation and analysis, effects of structure parameters of the system on the power flow transmission as well as on the isolation efficiency are fully investigated.
2001, 15(3).
Abstract:
The method to detect droplet transfer by means of arc spectrum, while the experiment sets, testing principle and data processing procedure, are presented. The experiment and analysis results show that arc spectrum signal can be utilized to detect and measure the transfer procedure, the transfer modes and the transfer parameters. The arc spectrum signal enjoys excellent quality with high signal amplitude. Each transfer mode has its specific typical signal mode, and the pulse outline corresponds to an integrated transferring procedure of one droplet. All these features of arc spectrum signal can be easily applied in the control of transfer procedure, the identification and stabilization of transfer mode and the measurement of transfer parameters.
The method to detect droplet transfer by means of arc spectrum, while the experiment sets, testing principle and data processing procedure, are presented. The experiment and analysis results show that arc spectrum signal can be utilized to detect and measure the transfer procedure, the transfer modes and the transfer parameters. The arc spectrum signal enjoys excellent quality with high signal amplitude. Each transfer mode has its specific typical signal mode, and the pulse outline corresponds to an integrated transferring procedure of one droplet. All these features of arc spectrum signal can be easily applied in the control of transfer procedure, the identification and stabilization of transfer mode and the measurement of transfer parameters.
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