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RSS2017 Vol. 36, No. 1
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2017, 36(1): 1-16.
doi: 10.13433/j.cnki.1003-8728.2017.0101
PDF 1432KB
Abstract:
This paper introduces the problems faced by manufacturing both at home and abroad, the background of Germany Industry 4.0, the development process of industry 1.0~4.0 and the driving mode of corresponding power. The essence of the Germany Industry 4.0, the four network platform and the five major innovative technologies are analyzed. This paper discusses the ten key areas and 23 key directions of Chinese manufacturing 2025 strategic planning, the basic ideas and key tasks of Chinese intelligent manufacturing. It is pointed there are three important architectures of Intelligent plant which are products and system architecture, value-added and enterprise architecture, data and information of IT infrastructure. And it is also pointed out there are three basic elements of intelligent machines which are the depth information for self perception, intelligent optimization and self decision making, precise control of self execution. This article points out the key equipment for intelligent manufacturing process implemented in all aspects of information access, real-time communication and dynamic interaction, decision analysis and control is the core equipment of intelligent manufacturing information. And the six types of important products are intelligent manufacturing basic communication equipment, intelligent manufacturing control system, new industrial sensor, manufacturing complex associated equipment, instrumentation and testing equipment, manufacturing information security products. It discusses Three approaches to the implementation of intelligent machines, and also analyzes the basic principles and characteristics of several typical intelligent machines. Finally,the importance of talent strategic planning of intelligent manufacturing core information equipment and its seven training methods was discussed, and puts forward ten specific measure for intelligent manufacturing core information and equipment personnel training strategy.
This paper introduces the problems faced by manufacturing both at home and abroad, the background of Germany Industry 4.0, the development process of industry 1.0~4.0 and the driving mode of corresponding power. The essence of the Germany Industry 4.0, the four network platform and the five major innovative technologies are analyzed. This paper discusses the ten key areas and 23 key directions of Chinese manufacturing 2025 strategic planning, the basic ideas and key tasks of Chinese intelligent manufacturing. It is pointed there are three important architectures of Intelligent plant which are products and system architecture, value-added and enterprise architecture, data and information of IT infrastructure. And it is also pointed out there are three basic elements of intelligent machines which are the depth information for self perception, intelligent optimization and self decision making, precise control of self execution. This article points out the key equipment for intelligent manufacturing process implemented in all aspects of information access, real-time communication and dynamic interaction, decision analysis and control is the core equipment of intelligent manufacturing information. And the six types of important products are intelligent manufacturing basic communication equipment, intelligent manufacturing control system, new industrial sensor, manufacturing complex associated equipment, instrumentation and testing equipment, manufacturing information security products. It discusses Three approaches to the implementation of intelligent machines, and also analyzes the basic principles and characteristics of several typical intelligent machines. Finally,the importance of talent strategic planning of intelligent manufacturing core information equipment and its seven training methods was discussed, and puts forward ten specific measure for intelligent manufacturing core information and equipment personnel training strategy.
2017, 36(1): 17-22.
doi: 10.13433/j.cnki.1003-8728.2017.0102
Abstract:
To solve the problems of low inheritance and reuse rate of the design experience and knowledge of the Fuze mechanism, the expert system technology based on knowledge engineering, the simulation process and parametric technique are introduced in the design process of fuze mechanism, to improve the quality of product, shorten the design cycle and reduce the cost. The intelligent design system of the fuze mechanism uses different methods of knowledge representation to meets the design requirements of the case from the knowledge base through the mixed reasoning method of cases and rules. The finite element analysis and parametric design are realized by using the simulation module and model base module of the system. The test of the system shows that the intelligent design system can achieve the reuse of knowledge and experience effectively.
To solve the problems of low inheritance and reuse rate of the design experience and knowledge of the Fuze mechanism, the expert system technology based on knowledge engineering, the simulation process and parametric technique are introduced in the design process of fuze mechanism, to improve the quality of product, shorten the design cycle and reduce the cost. The intelligent design system of the fuze mechanism uses different methods of knowledge representation to meets the design requirements of the case from the knowledge base through the mixed reasoning method of cases and rules. The finite element analysis and parametric design are realized by using the simulation module and model base module of the system. The test of the system shows that the intelligent design system can achieve the reuse of knowledge and experience effectively.
2017, 36(1): 23-28.
doi: 10.13433/j.cnki.1003-8728.2017.0103
Abstract:
In order to solve the co-existence problem of both various fault modes and causes in the electromechanical systems, an integrated fault diagnosis method based on improved FMEA (Failure mode and effect analysis) and failure propagation model is proposed. Firstly, by analyzing the failure modes and failure causes, the contribution rate of each failure cause to the corresponding failure mode can be obtained. And then, the failure propagation model is applied to deduce the fault diagnosis reasoning and to calculate the occurrence probability of each failure mode. Furthermore, the value of risk extended number (REN) is set to[0, 1] and used to measure the severity and detectability of the failures. Finally, the key components of electromechanical systems and their failure modes are obtained by comparing the occurrence probability and REN value. The proposed method provides a theoretical approach for making maintenance policy. Case study of a leveling system is illustrated, the results show that the proposed approach can be used to guide the reliability analysis and maintenance decision-making for electromechanical system.
In order to solve the co-existence problem of both various fault modes and causes in the electromechanical systems, an integrated fault diagnosis method based on improved FMEA (Failure mode and effect analysis) and failure propagation model is proposed. Firstly, by analyzing the failure modes and failure causes, the contribution rate of each failure cause to the corresponding failure mode can be obtained. And then, the failure propagation model is applied to deduce the fault diagnosis reasoning and to calculate the occurrence probability of each failure mode. Furthermore, the value of risk extended number (REN) is set to[0, 1] and used to measure the severity and detectability of the failures. Finally, the key components of electromechanical systems and their failure modes are obtained by comparing the occurrence probability and REN value. The proposed method provides a theoretical approach for making maintenance policy. Case study of a leveling system is illustrated, the results show that the proposed approach can be used to guide the reliability analysis and maintenance decision-making for electromechanical system.
2017, 36(1): 29-33.
doi: 10.13433/j.cnki.1003-8728.2017.0104
Abstract:
Head and neck coordination system of humanoid robot is developed in this paper, in which mainly includes the humanoid robot and control systems. Humanoid robot has 22 degrees of freedom, the control systems adopts upper and lower computer structure, and human-computer interface software with four kinds of work modes is completed. The kinematics simulation is carried out on eye circumference rotation and the coordinated movement of the eye and neck via ADAMS software. The experiments show that the robot's facial organs can realistically reproduce the eight basic expressions in head and neck coordination system and also achieve more rich and various expressions combined with neck movement, such as guilt, laugh and arrogance and so on. It can realize the reliability detection and tracking of the ball and face based on coordination of head and neck.
Head and neck coordination system of humanoid robot is developed in this paper, in which mainly includes the humanoid robot and control systems. Humanoid robot has 22 degrees of freedom, the control systems adopts upper and lower computer structure, and human-computer interface software with four kinds of work modes is completed. The kinematics simulation is carried out on eye circumference rotation and the coordinated movement of the eye and neck via ADAMS software. The experiments show that the robot's facial organs can realistically reproduce the eight basic expressions in head and neck coordination system and also achieve more rich and various expressions combined with neck movement, such as guilt, laugh and arrogance and so on. It can realize the reliability detection and tracking of the ball and face based on coordination of head and neck.
2017, 36(1): 34-38.
doi: 10.13433/j.cnki.1003-8728.2017.0105
Abstract:
In order to study the impact of combustion chamber shape on the alcohol ether fuel engine emissions, the combustion process and emission characteristics of engines with five different combustion chamber shapes were numerically simulated by the software AVL_Fire. The results show that, the effects of combustion chamber shape on the turbulent kinetic energy mainly appear near the TDC. The NO formation area is large and it spreads basically throughout the entire combustion chamber. But Soot is mainly distributed near the high temperature oil beam and the pit wall. Straight chamber A and the open chamber B have lower soot emission but higher NO emission.The narrow caliber and flat base chamber D discharges less NO but more soot. The NO and soot emissions of the narrow caliber and sharp base chamber E are both lower, which means the emission characteristics is better.
In order to study the impact of combustion chamber shape on the alcohol ether fuel engine emissions, the combustion process and emission characteristics of engines with five different combustion chamber shapes were numerically simulated by the software AVL_Fire. The results show that, the effects of combustion chamber shape on the turbulent kinetic energy mainly appear near the TDC. The NO formation area is large and it spreads basically throughout the entire combustion chamber. But Soot is mainly distributed near the high temperature oil beam and the pit wall. Straight chamber A and the open chamber B have lower soot emission but higher NO emission.The narrow caliber and flat base chamber D discharges less NO but more soot. The NO and soot emissions of the narrow caliber and sharp base chamber E are both lower, which means the emission characteristics is better.
2017, 36(1): 39-45.
doi: 10.13433/j.cnki.1003-8728.2017.0106
Abstract:
For the problem of reliability evaluation of the spring contact used in sliding connection of high-voltage circuit breaker's embedded pole in the case of minimum sample and zero-failure reliability test evaluation, the incomplete gamma distribution is adopted as a prior distribution of the spring contact failure probability, the mathematical model of accumulation failure probability is established based on the hierarchical Bayesian reliability assessment method. According to the least square method, the undetermined parameters of the two parameter Weibull distribution are solved and the reliability mathematical model is obtained for the canted spring contact. The results verify the reasonable of applying the incomplete gamma distribution to the reliability evaluation of the hierarchical Bayesian, which provides a guide for evaluating the reliability of spring contact.
For the problem of reliability evaluation of the spring contact used in sliding connection of high-voltage circuit breaker's embedded pole in the case of minimum sample and zero-failure reliability test evaluation, the incomplete gamma distribution is adopted as a prior distribution of the spring contact failure probability, the mathematical model of accumulation failure probability is established based on the hierarchical Bayesian reliability assessment method. According to the least square method, the undetermined parameters of the two parameter Weibull distribution are solved and the reliability mathematical model is obtained for the canted spring contact. The results verify the reasonable of applying the incomplete gamma distribution to the reliability evaluation of the hierarchical Bayesian, which provides a guide for evaluating the reliability of spring contact.
2017, 36(1): 46-51.
doi: 10.13433/j.cnki.1003-8728.2017.0107
Abstract:
According to the wide-band, nonlinear and non-stationary characteristics of the mechanical equipment vibration signals, a self-adaptive noise reduction method based on singular value energy standard spectrum was proposed. Firstly, the embedding dimension of phase space reconstruction was calculated by using the method of the average divergence degree of nearest neighbors, and then the phase space reconstruction matrix was decomposed with singular value decomposition. Finally the concept of singular value energy standard spectrum was put forward, and reconstruction order number was determined according to the inflexion position in order to refactor useful component parts, so as to realize the signal noise reduction. The analysis results of numerical simulation and cylinder head vibration signal showed that the proposed method can not only eliminate noise in the signal effectively but also retain the original signal characteristic effectively and enhance the signal-to-noise ratio.
According to the wide-band, nonlinear and non-stationary characteristics of the mechanical equipment vibration signals, a self-adaptive noise reduction method based on singular value energy standard spectrum was proposed. Firstly, the embedding dimension of phase space reconstruction was calculated by using the method of the average divergence degree of nearest neighbors, and then the phase space reconstruction matrix was decomposed with singular value decomposition. Finally the concept of singular value energy standard spectrum was put forward, and reconstruction order number was determined according to the inflexion position in order to refactor useful component parts, so as to realize the signal noise reduction. The analysis results of numerical simulation and cylinder head vibration signal showed that the proposed method can not only eliminate noise in the signal effectively but also retain the original signal characteristic effectively and enhance the signal-to-noise ratio.
2017, 36(1): 52-57.
doi: 10.13433/j.cnki.1003-8728.2017.0108
Abstract:
Owing to the nonlinearity and time-variation in the direct drive pump-controlled pressure servo system, a conventional PID control method causes poor adaptability, great pressure fluctuation and poor tracking control performances. Based on the influence of the PID parameters on the response characteristic of the pressure servo system, the adaptive fuzzy PID controller that adjusts the PID parameters adaptively based on the error and change in error was designed. The simulations and experiments on the conventional PID control and the adaptive fuzzy PID control of the direct drive pump-controlled pressure servo system were carried out. The results show that the adaptive fuzzy PID controller can greatly improve the performance of the conventional PID control method and has fast response, less pressure fluctuation, small sluggishness and overshooting. The dynamic performance of the pressure servo system and its control accuracy are improved.
Owing to the nonlinearity and time-variation in the direct drive pump-controlled pressure servo system, a conventional PID control method causes poor adaptability, great pressure fluctuation and poor tracking control performances. Based on the influence of the PID parameters on the response characteristic of the pressure servo system, the adaptive fuzzy PID controller that adjusts the PID parameters adaptively based on the error and change in error was designed. The simulations and experiments on the conventional PID control and the adaptive fuzzy PID control of the direct drive pump-controlled pressure servo system were carried out. The results show that the adaptive fuzzy PID controller can greatly improve the performance of the conventional PID control method and has fast response, less pressure fluctuation, small sluggishness and overshooting. The dynamic performance of the pressure servo system and its control accuracy are improved.
2017, 36(1): 58-67.
doi: 10.13433/j.cnki.1003-8728.2017.0109
Abstract:
For highly nonlinear relationship between LS-WEDM (low speed wire electrical discharge machining) cutting process indicators and process parameters, it is difficult to achieve optimization of processing parameters. For this problem, taking SKD11 die steel as a test object, a Taguchi experiment was designed with water pressure, pulse-on time, pulse-off time, peak current and the feed rate as variable factors, the surface roughness (Ra) and the material removal rate (MRR) for processing indicators, utilizing gray analysis method to analyze the effect of processing parameters on the process indicators; secondly to establish an improved gray neural network model for predicting Ra and MRR, the average relative error are of 7.92% and 8.13%, indicating that the present model can be mapped WEDM cutting process of law SKD11 die steel and can successfully predict the Ra and MRR. It provides an evidence for selecting the process parameters to cut SKD11 die steel via WEDM. Looking for a set of optimal parameters has a certain reference value for WEDM SKD11 die steel.
For highly nonlinear relationship between LS-WEDM (low speed wire electrical discharge machining) cutting process indicators and process parameters, it is difficult to achieve optimization of processing parameters. For this problem, taking SKD11 die steel as a test object, a Taguchi experiment was designed with water pressure, pulse-on time, pulse-off time, peak current and the feed rate as variable factors, the surface roughness (Ra) and the material removal rate (MRR) for processing indicators, utilizing gray analysis method to analyze the effect of processing parameters on the process indicators; secondly to establish an improved gray neural network model for predicting Ra and MRR, the average relative error are of 7.92% and 8.13%, indicating that the present model can be mapped WEDM cutting process of law SKD11 die steel and can successfully predict the Ra and MRR. It provides an evidence for selecting the process parameters to cut SKD11 die steel via WEDM. Looking for a set of optimal parameters has a certain reference value for WEDM SKD11 die steel.
2017, 36(1): 68-73.
doi: 10.13433/j.cnki.1003-8728.2017.0110
Abstract:
A thrust force model for carbon fiber reinforced plastics (CFRP)/aluminum alloys stacks is established in this paper. Firstly, drilling process is described according to the stack style and five stages are addressed. Secondly, a model for dynamic thrust force in drilling of CFRP/aluminum-alloy stacks is proposed and then the integration limits in the model are analyzed with accordance to the drilling stages. Finally, drilling experiments of stack structure are conducted to obtain the instantaneous thrust forces signal. It shows that the present model is in an well agreement with the experimental data. Therefore, the present model is capable to predict the dynamic thrust force in drilling of CFRP/aluminum-alloy stacks.
A thrust force model for carbon fiber reinforced plastics (CFRP)/aluminum alloys stacks is established in this paper. Firstly, drilling process is described according to the stack style and five stages are addressed. Secondly, a model for dynamic thrust force in drilling of CFRP/aluminum-alloy stacks is proposed and then the integration limits in the model are analyzed with accordance to the drilling stages. Finally, drilling experiments of stack structure are conducted to obtain the instantaneous thrust forces signal. It shows that the present model is in an well agreement with the experimental data. Therefore, the present model is capable to predict the dynamic thrust force in drilling of CFRP/aluminum-alloy stacks.
2017, 36(1): 74-82.
doi: 10.13433/j.cnki.1003-8728.2017.0111
Abstract:
The machining method of face milling the tooth profile of cycloidal gear with face mill instead of ball end mill is proposed. A method is proposed to solve local interference and collision interference of face mill by using the tool rake angle and side inclination angle. The calculation formula of the tool rake angle for machining cycloidal gear without interference is obtained. The face milling process of the cycloidal gear under high speed is realized by using five axis linkage vertical machining center and the cycloid gear prototype after finishing is obtained. The machining accuracy and surface roughness of tooth profile of the cycloid gear after finishing are measured and analyzed. The maximum deviation of the cycloid gear prototype is 0.051 mm, the smallest deviation is -0.085 0 mm. The average surface roughness Ra of the tooth profile is 0.504 6 μm. The results show that the method of face milling cycloidal gear under high speed can achieve the machining accuracy of the grinding cycloidal gear so as to realize the goal of "milling instead of grinding" in machining cycloidal gear.
The machining method of face milling the tooth profile of cycloidal gear with face mill instead of ball end mill is proposed. A method is proposed to solve local interference and collision interference of face mill by using the tool rake angle and side inclination angle. The calculation formula of the tool rake angle for machining cycloidal gear without interference is obtained. The face milling process of the cycloidal gear under high speed is realized by using five axis linkage vertical machining center and the cycloid gear prototype after finishing is obtained. The machining accuracy and surface roughness of tooth profile of the cycloid gear after finishing are measured and analyzed. The maximum deviation of the cycloid gear prototype is 0.051 mm, the smallest deviation is -0.085 0 mm. The average surface roughness Ra of the tooth profile is 0.504 6 μm. The results show that the method of face milling cycloidal gear under high speed can achieve the machining accuracy of the grinding cycloidal gear so as to realize the goal of "milling instead of grinding" in machining cycloidal gear.
2017, 36(1): 83-88.
doi: 10.13433/j.cnki.1003-8728.2017.0112
Abstract:
Planar mechanisms are widely applied to many machines, but the impact of their long transmission distance on the kinematic accuracy can not be ignored. The influence factors of reliability in precision of mechanism kinematic were divided into non-cumulative factors and cumulative factors. The analysis methods of reliability in precision of planar mechanism motion were given under the conditions of coupling effects by cumulative factors and non-cumulative factors. The model of wear reliability interference was established based on the Archard wear model. The calculating method for rated life was proposed under the condition of rotational speeds. The crank slider mechanism was analyzed as an example, which is widely used in engineering. The results showed that the cumulative factors is the main factor which affects the kinematic accuracy of mechanisms, the mechanical reliability falls sharply when cumulative factors accumulate to a certain extent and the rated life of various institutions is calculated under the rated speed.
Planar mechanisms are widely applied to many machines, but the impact of their long transmission distance on the kinematic accuracy can not be ignored. The influence factors of reliability in precision of mechanism kinematic were divided into non-cumulative factors and cumulative factors. The analysis methods of reliability in precision of planar mechanism motion were given under the conditions of coupling effects by cumulative factors and non-cumulative factors. The model of wear reliability interference was established based on the Archard wear model. The calculating method for rated life was proposed under the condition of rotational speeds. The crank slider mechanism was analyzed as an example, which is widely used in engineering. The results showed that the cumulative factors is the main factor which affects the kinematic accuracy of mechanisms, the mechanical reliability falls sharply when cumulative factors accumulate to a certain extent and the rated life of various institutions is calculated under the rated speed.
2017, 36(1): 89-94.
doi: 10.13433/j.cnki.1003-8728.2017.0113
Abstract:
In order to reduce the fracture damage and the not uniform quality of the machined surface in cutting of germanium element, according to the anisotropic characteristics of germanium single crystal structure, stress the change of the cleavage plane and slip surface of single crystal germanium were studied. The criterion of the degree of the crystal orientation influencing the brittle-ductile removal mode of chip was given. A stress calculation model for the cleavage plane and slip plane of single-crystal germanium arbitrary crystal plane was established, and anisotropy distribution law of machined surface roughness of single-crystal germanium was analyzed. The relationship between the brittle-ductile removal mode of chip and the crystal orientation of the arbitrary crystal plane and typical crystal plane was calculated. The correctness and effectiveness of the criterion and model were verified via ultra precision cutting experiment.
In order to reduce the fracture damage and the not uniform quality of the machined surface in cutting of germanium element, according to the anisotropic characteristics of germanium single crystal structure, stress the change of the cleavage plane and slip surface of single crystal germanium were studied. The criterion of the degree of the crystal orientation influencing the brittle-ductile removal mode of chip was given. A stress calculation model for the cleavage plane and slip plane of single-crystal germanium arbitrary crystal plane was established, and anisotropy distribution law of machined surface roughness of single-crystal germanium was analyzed. The relationship between the brittle-ductile removal mode of chip and the crystal orientation of the arbitrary crystal plane and typical crystal plane was calculated. The correctness and effectiveness of the criterion and model were verified via ultra precision cutting experiment.
2017, 36(1): 95-101.
doi: 10.13433/j.cnki.1003-8728.2017.0114
Abstract:
The in-line inspection (ILI) technology plays an essential role in oil and gas pipelines' safe operation. This paper designs a novel active helical pipeline measurement device based on helical measurement principles, which can control its own helical motion actively. We integrate the measurement device with a distance sensor and an angle sensor and then conduct several comparative experiments and experiments on defect inspection. The inner wall models of a pipeline are retrieved by using the MATLAB software and the experiments' data. The experimental results show that the measurement device is feasible, and the comparative experiments show that the measurement device is different from conventional methods. The results also prove that the circumference division active helical pipeline measurement device is more accurate and can be trucked by PIGs or pipe robots, being able to be applied to micro-pipelines or unpiggable pipelines.
The in-line inspection (ILI) technology plays an essential role in oil and gas pipelines' safe operation. This paper designs a novel active helical pipeline measurement device based on helical measurement principles, which can control its own helical motion actively. We integrate the measurement device with a distance sensor and an angle sensor and then conduct several comparative experiments and experiments on defect inspection. The inner wall models of a pipeline are retrieved by using the MATLAB software and the experiments' data. The experimental results show that the measurement device is feasible, and the comparative experiments show that the measurement device is different from conventional methods. The results also prove that the circumference division active helical pipeline measurement device is more accurate and can be trucked by PIGs or pipe robots, being able to be applied to micro-pipelines or unpiggable pipelines.
2017, 36(1): 102-107.
doi: 10.13433/j.cnki.1003-8728.2017.0115
Abstract:
To solve the problem of moving object tracking in video image sequences, this paper presents a novel algorithm that combines the Chan and Vese Geodesic Active Contour (CV-GAC) model with graph cut optimization. Firstly, the object's active contours are obtained by using the Gaussian mixture model and background subtraction; then, the contour of the initial curve is automatically set in the moving area, and the mathematical morphological operation is carried out by using the geodesic level set model to adaptively treat the object's topology change and globally optimize the energy function with the graph cut optimization. The experimental results show that this method effectively shortens the time for the moving object segmentation, correctly and quickly extracting the active contours of moving targets.
To solve the problem of moving object tracking in video image sequences, this paper presents a novel algorithm that combines the Chan and Vese Geodesic Active Contour (CV-GAC) model with graph cut optimization. Firstly, the object's active contours are obtained by using the Gaussian mixture model and background subtraction; then, the contour of the initial curve is automatically set in the moving area, and the mathematical morphological operation is carried out by using the geodesic level set model to adaptively treat the object's topology change and globally optimize the energy function with the graph cut optimization. The experimental results show that this method effectively shortens the time for the moving object segmentation, correctly and quickly extracting the active contours of moving targets.
2017, 36(1): 108-113.
doi: 10.13433/j.cnki.1003-8728.2017.0116
Abstract:
In view of the decision problem of cabin layout design, considering the influence of the joint torque on joint comfort, the method to evaluate the layout scheme through the upper limb operating comfort was proposed. The CATIA software was used to simulate the main operating posture, the human body biomechanical model was adopted to analyze joint torque, the upper limb dynamic model was established based on Kane dynamic equation, and the joint torque was introduced to evaluate joint comfort with the help of NASA's power model, the evaluation problem of the overall comfort of upper limb with different joint angle combination was solved. The curve of joint angle and the upper limb operating comfort can provide a reference for cabin layout evaluation and optimization. The proposed method can find design flaws in time by considering human factors in the early design stage, and thus improve the design efficiency.
In view of the decision problem of cabin layout design, considering the influence of the joint torque on joint comfort, the method to evaluate the layout scheme through the upper limb operating comfort was proposed. The CATIA software was used to simulate the main operating posture, the human body biomechanical model was adopted to analyze joint torque, the upper limb dynamic model was established based on Kane dynamic equation, and the joint torque was introduced to evaluate joint comfort with the help of NASA's power model, the evaluation problem of the overall comfort of upper limb with different joint angle combination was solved. The curve of joint angle and the upper limb operating comfort can provide a reference for cabin layout evaluation and optimization. The proposed method can find design flaws in time by considering human factors in the early design stage, and thus improve the design efficiency.
2017, 36(1): 114-118.
doi: 10.13433/j.cnki.1003-8728.2017.0117
Abstract:
In engineering, the complex car body surfaces cannot be described by using one single surface; thus the continuity conditions of the cubic Q-Bézier surfaces with multiple shape parameters were investigated. A car body design method based on cubic Q-Bézier surfaces with multiple shape parameters is proposed in this paper, which describes the car body that has a group of cubic Q-Bézier surfaces with multiple shape parameters in the design process. The group of cubic Q-Bézier surfaces are created and blended continuously; the surfaces' boundary position and shape parameters were modified efficiently, thus obtaining the new car body design solutions. This design method, based on the principle of cubic Q-Bézier surfaces that generates and blends multiple shape parameters, can quickly edit the surfaces by adjusting the boundary curve and obtain many design solutions, being widely applied to modern industrial design.
In engineering, the complex car body surfaces cannot be described by using one single surface; thus the continuity conditions of the cubic Q-Bézier surfaces with multiple shape parameters were investigated. A car body design method based on cubic Q-Bézier surfaces with multiple shape parameters is proposed in this paper, which describes the car body that has a group of cubic Q-Bézier surfaces with multiple shape parameters in the design process. The group of cubic Q-Bézier surfaces are created and blended continuously; the surfaces' boundary position and shape parameters were modified efficiently, thus obtaining the new car body design solutions. This design method, based on the principle of cubic Q-Bézier surfaces that generates and blends multiple shape parameters, can quickly edit the surfaces by adjusting the boundary curve and obtain many design solutions, being widely applied to modern industrial design.
2017, 36(1): 119-126.
doi: 10.13433/j.cnki.1003-8728.2017.0118
Abstract:
A general expression is derived to describe heat generation in friction stir welding (FSW) by a tool with cylindrical pin. Three heat source models are obtained by calculating frictional stresses in the expression according to sling friction, sticking friction and the combination of them, respectively. In ABAQUS, these heat source models are implemented in subroutines to apply loads, and a model for simulating the temperature field of FSW of 12.7 mm-thick 6061-T6 aluminum alloy plate is established. The numerical analysis results are compared with the experimental. It is found that heat source models based on sticking friction and combination of sliding and sticking friction can well predict temperature field and nearly produces the same results for steady state of welding, while the model based on sliding friction gives higher temperature than the experimental. By varying relevant parameters of the model, influences of boundary conditions, preheating time, welding parameters and structural parameters of the tool are systematically studied. A number of rules and indices are obtained.
A general expression is derived to describe heat generation in friction stir welding (FSW) by a tool with cylindrical pin. Three heat source models are obtained by calculating frictional stresses in the expression according to sling friction, sticking friction and the combination of them, respectively. In ABAQUS, these heat source models are implemented in subroutines to apply loads, and a model for simulating the temperature field of FSW of 12.7 mm-thick 6061-T6 aluminum alloy plate is established. The numerical analysis results are compared with the experimental. It is found that heat source models based on sticking friction and combination of sliding and sticking friction can well predict temperature field and nearly produces the same results for steady state of welding, while the model based on sliding friction gives higher temperature than the experimental. By varying relevant parameters of the model, influences of boundary conditions, preheating time, welding parameters and structural parameters of the tool are systematically studied. A number of rules and indices are obtained.
2017, 36(1): 127-138.
doi: 10.13433/j.cnki.1003-8728.2017.0119
Abstract:
The investigation on dynamical behavior of an aero-engine rotor system with loose inner ring was performed. The relative motion between the inner ring and the lock nut was proposed according to the geometrical and structural features of a loose inner ring, based on which the calculation method of the sliding frictional load on the lock nut was presented. This project set up a model for a vertically assembled rotor with loose inner ring, which accounted for both the stiffness nonlinearity and the damp nonlinearity introduced by the clearance and the frictional load on the lock nut respectively. The dynamical equation was solved numerically, which gave the dynamical responses of the rotor system, like wave plot, frequency spectrum and locus of the disk center, etc. The influences of the structural parameters on the rotor, say, the unbalance mass of the rotor, the clearance between the inner ring and the journal, the tightening torque of the lock nut, were identified quantitatively. It turned out that the synchronous forward whirl was promoted and the instability of the rotor was possibly to occur due to the internal friction dependent on relative sliding motion and proportional to the tightening torque; a rotor instability was observed with frequencies, say, the nature frequency, the rotating frequency, and the difference between them; the boundary of rotor instability was defined in terms of parameters, say, unbalance mass, the clearance between the inner ring and the journal and the tightening torque; an appropriate parameter condition was of significance to avoid the rotor instability.
The investigation on dynamical behavior of an aero-engine rotor system with loose inner ring was performed. The relative motion between the inner ring and the lock nut was proposed according to the geometrical and structural features of a loose inner ring, based on which the calculation method of the sliding frictional load on the lock nut was presented. This project set up a model for a vertically assembled rotor with loose inner ring, which accounted for both the stiffness nonlinearity and the damp nonlinearity introduced by the clearance and the frictional load on the lock nut respectively. The dynamical equation was solved numerically, which gave the dynamical responses of the rotor system, like wave plot, frequency spectrum and locus of the disk center, etc. The influences of the structural parameters on the rotor, say, the unbalance mass of the rotor, the clearance between the inner ring and the journal, the tightening torque of the lock nut, were identified quantitatively. It turned out that the synchronous forward whirl was promoted and the instability of the rotor was possibly to occur due to the internal friction dependent on relative sliding motion and proportional to the tightening torque; a rotor instability was observed with frequencies, say, the nature frequency, the rotating frequency, and the difference between them; the boundary of rotor instability was defined in terms of parameters, say, unbalance mass, the clearance between the inner ring and the journal and the tightening torque; an appropriate parameter condition was of significance to avoid the rotor instability.
2017, 36(1): 139-146.
doi: 10.13433/j.cnki.1003-8728.2017.0120
Abstract:
Among the vibration tests of spacecraft, the acceleration is usually the only specification in traditional test method which generally results in overtesting problem. The force limiting can solve this problem well by dual control of the acceleration and force. Force specification is the foundation of the force limited vibration test. The principle of complex two-degree-of-freedom method and its process to get the force specification are derived in detail. A test verification is designed, and the input acceleration decreased about 19.5 dB and 17.2 dB at the first resonance frequencies of the test item. The test result demonstrates that the specification of force limited test is closer to the reality than traditional acceleration test.
Among the vibration tests of spacecraft, the acceleration is usually the only specification in traditional test method which generally results in overtesting problem. The force limiting can solve this problem well by dual control of the acceleration and force. Force specification is the foundation of the force limited vibration test. The principle of complex two-degree-of-freedom method and its process to get the force specification are derived in detail. A test verification is designed, and the input acceleration decreased about 19.5 dB and 17.2 dB at the first resonance frequencies of the test item. The test result demonstrates that the specification of force limited test is closer to the reality than traditional acceleration test.
2017, 36(1): 147-151.
doi: 10.13433/j.cnki.1003-8728.2017.0121
Abstract:
The dynamics simulation of a tethered system located on elliptical orbit is studied by using the so-called "cone" dynamics models. The tethered system is a structure that has a huge area of major satellite and minor satellite connected through some long ropes. On the strength of the huge area of the major satellite and the super length of the ropes, the quality rods and the little cylinder connected with force are built respectively. Based on the dynamic model, the dynamics simulation of the major satellite and the whole tethered system is discussed. The discussion results show that the attitude control of the tethered system on elliptic orbit is stable and that the major satellite extends normally. The tethered system eliminates the need to use force in the process of setting because the rope stretched in its range.
The dynamics simulation of a tethered system located on elliptical orbit is studied by using the so-called "cone" dynamics models. The tethered system is a structure that has a huge area of major satellite and minor satellite connected through some long ropes. On the strength of the huge area of the major satellite and the super length of the ropes, the quality rods and the little cylinder connected with force are built respectively. Based on the dynamic model, the dynamics simulation of the major satellite and the whole tethered system is discussed. The discussion results show that the attitude control of the tethered system on elliptic orbit is stable and that the major satellite extends normally. The tethered system eliminates the need to use force in the process of setting because the rope stretched in its range.
2017, 36(1): 152-160.
doi: 10.13433/j.cnki.1003-8728.2017.0122
Abstract:
As the aero-engine's baseline is difficult to get, Support Vector Regression (SVR) is used with data from monitoring systems of manufacturers and Quick Access Recorder (QAR) to do baseline mining analysis, providing a variety of ways to get baseline and the results turned out to have a good reliability. SVR is fast and precise in dealing with nonlinear regression analysis. Single parameter regression and multi-parameter regression can be processed by using SVR. The conclusion can be drawn from analysis of calculation results that multi-parameter regression of SVR has a lot of advantages such as small deviation and high accuracy compared with linear regression and single parameter regression of SVR. As a result, the accuracy of the aero-engine's monitoring can be improved effectively.
As the aero-engine's baseline is difficult to get, Support Vector Regression (SVR) is used with data from monitoring systems of manufacturers and Quick Access Recorder (QAR) to do baseline mining analysis, providing a variety of ways to get baseline and the results turned out to have a good reliability. SVR is fast and precise in dealing with nonlinear regression analysis. Single parameter regression and multi-parameter regression can be processed by using SVR. The conclusion can be drawn from analysis of calculation results that multi-parameter regression of SVR has a lot of advantages such as small deviation and high accuracy compared with linear regression and single parameter regression of SVR. As a result, the accuracy of the aero-engine's monitoring can be improved effectively.
2017, 36(1): 161-164.
doi: 10.13433/j.cnki.1003-8728.2017.0123
Abstract:
This paper describes the working principle of the aircraft engine ignition system, and discusses the factors which affect the minimum ignition voltage of the semiconductor igniter according to the fomula derivation. From the bad environment of the igniter tip, the electrode materials that satisfy the requirement is listed. At the same time, the relationship between the electrode gap, the energy storage capacity and the minimum ignition voltage is investigated based on the practical test data. The calculation progress of electrode gap design is stated in detail through nonlinear analysis, and then provides the basis for reasonable choice of the electrode gap of semiconductor igniter.
This paper describes the working principle of the aircraft engine ignition system, and discusses the factors which affect the minimum ignition voltage of the semiconductor igniter according to the fomula derivation. From the bad environment of the igniter tip, the electrode materials that satisfy the requirement is listed. At the same time, the relationship between the electrode gap, the energy storage capacity and the minimum ignition voltage is investigated based on the practical test data. The calculation progress of electrode gap design is stated in detail through nonlinear analysis, and then provides the basis for reasonable choice of the electrode gap of semiconductor igniter.
