Author Center
Editor Work
Peer Review
Editorial Entry
Email Alert
RSS2015 Vol. 34, No. 8
Display Method:
2015, 34(8): 1149-1152.
doi: 10.13433/j.cnki.1003-8728.2015.0801
PDF 2048KB
Abstract:
Analytical method has been used to study the load distribution along the helix of thread when the bolt-joint is subjected to eccentric loading. The equation of coordination deformation of bolt-joint with bending moment is derived based on the theory of elasticity and a numerical method was applied to obtain the approximate solution. The formula for load distribution of bolt-joint under eccentric loading is deduced. Taking the bolt-joint of M16x2 as an example, the load distribution of thread is simulated using the MATLAB software and the results are consistent with those of photoelastic experiment.
Analytical method has been used to study the load distribution along the helix of thread when the bolt-joint is subjected to eccentric loading. The equation of coordination deformation of bolt-joint with bending moment is derived based on the theory of elasticity and a numerical method was applied to obtain the approximate solution. The formula for load distribution of bolt-joint under eccentric loading is deduced. Taking the bolt-joint of M16x2 as an example, the load distribution of thread is simulated using the MATLAB software and the results are consistent with those of photoelastic experiment.
2015, 34(8): 1153-1156.
doi: 10.13433/j.cnki.1003-8728.2015.0802
Abstract:
To obtain dynamic characteristics for contact forces during continuous meshing of multi-teeth, a dynamic model of meshing muti-teeth is built as follows: a gear is divided into a rigid gear wheel body and circumferentially rotatable flexible teeth; the elastic elements composed of rotational spring-damper combinations are used to connect them based on the deflection mechanism of real teeth; a complaint contact force model called Lankarani & Nikravesh model and Kuhn-Tucker constraint equations are utilized to realize the meshing. The example shows that calculated contact force in meshing region is in good agreement with that obtained with machine design method. The calculated meshing impact is verified through a gear impact test. The results of numerical computation and experiment indicate that the model can reflect the characteristics of tooth kinematics contact and kinetics contact and it is suitable for modeling gear drive systems.
To obtain dynamic characteristics for contact forces during continuous meshing of multi-teeth, a dynamic model of meshing muti-teeth is built as follows: a gear is divided into a rigid gear wheel body and circumferentially rotatable flexible teeth; the elastic elements composed of rotational spring-damper combinations are used to connect them based on the deflection mechanism of real teeth; a complaint contact force model called Lankarani & Nikravesh model and Kuhn-Tucker constraint equations are utilized to realize the meshing. The example shows that calculated contact force in meshing region is in good agreement with that obtained with machine design method. The calculated meshing impact is verified through a gear impact test. The results of numerical computation and experiment indicate that the model can reflect the characteristics of tooth kinematics contact and kinetics contact and it is suitable for modeling gear drive systems.
2015, 34(8): 1157-1160.
doi: 10.13433/j.cnki.1003-8728.2015.0803
Abstract:
Dust shield in down-the-hole(DTH)drill,as a key component of its dust abatement system,plays an important role in dust-sucking capability,cleaning efficiency and operation reliability. Based on the analysis of internal flow field and structural parameters of the dust shield in DTH drill and a three-dimensional model built with Pro/e software, the flow field of dust shield was calculated with workbench software. An improved design scheme was proposed after exploring the influence of different structural parameters on sucking effect. And gas-solid two-phase flow was simulated and analyzed. The results show that the increase of the cylinder height of the dust shield will reduce the leakage of the leakage collar and is conducive to the collection of dust. When the cylinder diameter is 350 mm it has a beneficial effect on the stability of the internal flow field. The greater the inclination of exhaust pipe is, the better the dust collection capability of the shield has.
Dust shield in down-the-hole(DTH)drill,as a key component of its dust abatement system,plays an important role in dust-sucking capability,cleaning efficiency and operation reliability. Based on the analysis of internal flow field and structural parameters of the dust shield in DTH drill and a three-dimensional model built with Pro/e software, the flow field of dust shield was calculated with workbench software. An improved design scheme was proposed after exploring the influence of different structural parameters on sucking effect. And gas-solid two-phase flow was simulated and analyzed. The results show that the increase of the cylinder height of the dust shield will reduce the leakage of the leakage collar and is conducive to the collection of dust. When the cylinder diameter is 350 mm it has a beneficial effect on the stability of the internal flow field. The greater the inclination of exhaust pipe is, the better the dust collection capability of the shield has.
2015, 34(8): 1161-1165.
doi: 10.13433/j.cnki.1003-8728.2015.0804
Abstract:
In identifying the parameters with the empirical mode decomposition (EMD) method, there exists the deficiency of the mode separation of two intrinsic mode function (IMF) components with near frequency and the non-orthogonality between IMF components, which make the parameters identification results not accurate and stable enough. To solve these problems, we propose the improved EMD method which combines the wave group(WG) signal processing method with the orthogonal empirical mode decomposition(OEMD). Based on the improved EMD method, the parameter identification procedures for time varying structures with closely spaced modes are proposed and applied to the numerical simulation with a three degrees-of-freedom time varying dynamic model. The simulation results demonstrate that the proposed method has very good effectiveness, efficiency and has the advantages of identifying the parameters of time varying structures with closely spaced modes.
In identifying the parameters with the empirical mode decomposition (EMD) method, there exists the deficiency of the mode separation of two intrinsic mode function (IMF) components with near frequency and the non-orthogonality between IMF components, which make the parameters identification results not accurate and stable enough. To solve these problems, we propose the improved EMD method which combines the wave group(WG) signal processing method with the orthogonal empirical mode decomposition(OEMD). Based on the improved EMD method, the parameter identification procedures for time varying structures with closely spaced modes are proposed and applied to the numerical simulation with a three degrees-of-freedom time varying dynamic model. The simulation results demonstrate that the proposed method has very good effectiveness, efficiency and has the advantages of identifying the parameters of time varying structures with closely spaced modes.
2015, 34(8): 1166-1170.
doi: 10.13433/j.cnki.1003-8728.2015.0805
Abstract:
Focusing on the structural characteristics of a redundant parallel robot, we analyze its forward kinematics and then determine its workspace. Because of its execution points in different regions, its solutions for inverse kinematics are different. So we divide the solutions into two parts to obtain the execution points. Then we confirm the angular ranges of joints of the redundant parallel robot, plan its trajectory with the linear interpolation algorithm and simulate the trajectory. The simulation results prove the correctness of the workspace and trajectory of the redundant parallel robot.
Focusing on the structural characteristics of a redundant parallel robot, we analyze its forward kinematics and then determine its workspace. Because of its execution points in different regions, its solutions for inverse kinematics are different. So we divide the solutions into two parts to obtain the execution points. Then we confirm the angular ranges of joints of the redundant parallel robot, plan its trajectory with the linear interpolation algorithm and simulate the trajectory. The simulation results prove the correctness of the workspace and trajectory of the redundant parallel robot.
2015, 34(8): 1171-1176.
doi: 10.13433/j.cnki.1003-8728.2015.0806
Abstract:
In order to overcome the difficulty in grinding a complex curved surface, we put forward a flexible and parallel serial adaptive polishing mechanism which can adapt to the surface of a workpiece quickly. Its work space, kinematic and dynamic characteristics have been analyzed. We analyzed its degrees of freedom and degrees of coupling with the theory of topological structure based on the position and orientation characteristic equations. The performance curve and simulated diagram of work space was obtained with MATLAB. The virtual prototype model of adaptive polishing mechanism was built; the kinematic and dynamic characteristics of the adaptive polishing mechanism of the complex curved surface were analyzed. Advantages over the traditional polishing mechanism were also obtained through experiments.
In order to overcome the difficulty in grinding a complex curved surface, we put forward a flexible and parallel serial adaptive polishing mechanism which can adapt to the surface of a workpiece quickly. Its work space, kinematic and dynamic characteristics have been analyzed. We analyzed its degrees of freedom and degrees of coupling with the theory of topological structure based on the position and orientation characteristic equations. The performance curve and simulated diagram of work space was obtained with MATLAB. The virtual prototype model of adaptive polishing mechanism was built; the kinematic and dynamic characteristics of the adaptive polishing mechanism of the complex curved surface were analyzed. Advantages over the traditional polishing mechanism were also obtained through experiments.
2015, 34(8): 1177-1180.
doi: 10.13433/j.cnki.1003-8728.2015.0807
Abstract:
For the problem of omni-directional wheeled moving mechanism, an omni-directional tracked moving mechanism is introduced. The structural model of the omni-directional tracked moving mechanism is established with UG software, and the motion coordination principle of the moving mechanism is analyzed. The kinematics simulation analysis of the moving mechanism is conducted with the Adams simulation software, and the results demonstrate the effectiveness of the mechanism.
For the problem of omni-directional wheeled moving mechanism, an omni-directional tracked moving mechanism is introduced. The structural model of the omni-directional tracked moving mechanism is established with UG software, and the motion coordination principle of the moving mechanism is analyzed. The kinematics simulation analysis of the moving mechanism is conducted with the Adams simulation software, and the results demonstrate the effectiveness of the mechanism.
2015, 34(8): 1181-1185.
doi: 10.13433/j.cnki.1003-8728.2015.0808
Abstract:
A new method is presented for extracting feature lines on triangular surfaces. The initial feature line is extracted with the tracing-projection algorithm with a few feature points specified. Several sample points are obtained with uniform sampling the initial feature line. The sample points are then replaced by new feature points acquired with finding the maximum mean curvature point among the points around each sample point. A B-spline curve is fitted with the new feature points. Finally, the feature line which captures surface feature very well is obtained with projecting the B-spline curve on the triangular surfaces. Experimental results demonstrate that the feature line extracted with the present method can smoothly capture the object features.
A new method is presented for extracting feature lines on triangular surfaces. The initial feature line is extracted with the tracing-projection algorithm with a few feature points specified. Several sample points are obtained with uniform sampling the initial feature line. The sample points are then replaced by new feature points acquired with finding the maximum mean curvature point among the points around each sample point. A B-spline curve is fitted with the new feature points. Finally, the feature line which captures surface feature very well is obtained with projecting the B-spline curve on the triangular surfaces. Experimental results demonstrate that the feature line extracted with the present method can smoothly capture the object features.
2015, 34(8): 1186-1189.
doi: 10.13433/j.cnki.1003-8728.2015.0809
Abstract:
A forecasting method for any point space errors in machine tool working region is presented based on the shape function interpolation. Two different methods, finite element method interpolation and meshless method interpolation, have been analyzed. Based on the comparison between the advantages and disadvantages of the above two methods, a space error forecasting method by coupling finite element interpolation and a moving least squares meshless method interpolation for complexity shape was presented.
A forecasting method for any point space errors in machine tool working region is presented based on the shape function interpolation. Two different methods, finite element method interpolation and meshless method interpolation, have been analyzed. Based on the comparison between the advantages and disadvantages of the above two methods, a space error forecasting method by coupling finite element interpolation and a moving least squares meshless method interpolation for complexity shape was presented.
2015, 34(8): 1190-1200.
doi: 10.13433/j.cnki.1003-8728.2015.0810
Abstract:
In order to improve the machining precision of thin-walled parts milling force during machining in aircraft engines, the amount of milling force must be accurately predicted. In this paper, different approaches of three-dimensional milling force prediction modeling are discussed, which include multi-linear regression analysis model, infinitesimal milling force prediction model, finite element prediction models and artificial neural network model. And an impact of cutting parameter, tool geometry, workpiece material, cooling, tool material and tool wear on the cutting force is analyzed.
In order to improve the machining precision of thin-walled parts milling force during machining in aircraft engines, the amount of milling force must be accurately predicted. In this paper, different approaches of three-dimensional milling force prediction modeling are discussed, which include multi-linear regression analysis model, infinitesimal milling force prediction model, finite element prediction models and artificial neural network model. And an impact of cutting parameter, tool geometry, workpiece material, cooling, tool material and tool wear on the cutting force is analyzed.
2015, 34(8): 1201-1205.
doi: 10.13433/j.cnki.1003-8728.2015.0811
Abstract:
The traditional NURBS interpolation algorithms are time-consuming for large amount of calculations. To solve the problem, a predictor-corrector NURBS interpolation algorithm based on predicted error compensation is presented. The interpolation algorithm avoids derivative calculation with simple linearization calculations reducing computational complexity availably and increasing computational efficiency, and also can compensate the predicted value for approaching the real value according to the changing trend of curvature. As for the slow-convergent-speed problem of the traditional corrector formula, a new corrector formula based on the secant method is presented. The new corrector formula is superlinear convergence of numerical methods reducing times of iteration effectively. The simulation experiments demonstrate that the proposed algorithm has advanced characterization of less calculations and strong maneuverability, outstanding stability and excellent reliability; it also can effectively control the rate fluctuation, and satisfy the real-time interpolation requirement.
The traditional NURBS interpolation algorithms are time-consuming for large amount of calculations. To solve the problem, a predictor-corrector NURBS interpolation algorithm based on predicted error compensation is presented. The interpolation algorithm avoids derivative calculation with simple linearization calculations reducing computational complexity availably and increasing computational efficiency, and also can compensate the predicted value for approaching the real value according to the changing trend of curvature. As for the slow-convergent-speed problem of the traditional corrector formula, a new corrector formula based on the secant method is presented. The new corrector formula is superlinear convergence of numerical methods reducing times of iteration effectively. The simulation experiments demonstrate that the proposed algorithm has advanced characterization of less calculations and strong maneuverability, outstanding stability and excellent reliability; it also can effectively control the rate fluctuation, and satisfy the real-time interpolation requirement.
2015, 34(8): 1206-1210.
doi: 10.13433/j.cnki.1003-8728.2015.0812
Abstract:
A two-objective model was constructed for rescheduling problem with order modification in make-to-order flexible manufacturing system. The present model was designed to minimize both the tardy orders and the differences between rescheduling result and original sequence. The simulation models were built to imitate the running of scheduling and rescheduling scenes, and two rescheduling rules, right-extending and swapping to a period near due date, were proposed for the bi-objective rescheduling model. Running of rescheduling models was conducted. The results revealed that the rule of swapping to a period near due date achieved better performances than the right-extending rule.
A two-objective model was constructed for rescheduling problem with order modification in make-to-order flexible manufacturing system. The present model was designed to minimize both the tardy orders and the differences between rescheduling result and original sequence. The simulation models were built to imitate the running of scheduling and rescheduling scenes, and two rescheduling rules, right-extending and swapping to a period near due date, were proposed for the bi-objective rescheduling model. Running of rescheduling models was conducted. The results revealed that the rule of swapping to a period near due date achieved better performances than the right-extending rule.
2015, 34(8): 1211-1216.
doi: 10.13433/j.cnki.1003-8728.2015.0813
Abstract:
In this paper, a novel method of embedding breadth vs. depth simulation resource allocation mechanism into evolution algorithm with ordinal optimization, i.e. ESOO-BD, is proposed to solve a job shop scheduling problem under processing time variability (JSP-PTV) with the objective of minimizing the expected sum of earliness and tardiness penalties. In breadth vs. depth approach, a simulation allocation method that can dynamically allocate the computational resources to the search process and the performance evaluation process are introduced. Finally, the computational results on the benchmark instances show that the present method outperforms the existing method by achieving better solutions.
In this paper, a novel method of embedding breadth vs. depth simulation resource allocation mechanism into evolution algorithm with ordinal optimization, i.e. ESOO-BD, is proposed to solve a job shop scheduling problem under processing time variability (JSP-PTV) with the objective of minimizing the expected sum of earliness and tardiness penalties. In breadth vs. depth approach, a simulation allocation method that can dynamically allocate the computational resources to the search process and the performance evaluation process are introduced. Finally, the computational results on the benchmark instances show that the present method outperforms the existing method by achieving better solutions.
2015, 34(8): 1217-1221.
doi: 10.13433/j.cnki.1003-8728.2015.0814
Abstract:
This paper proposed the design of a desktop reconfigurable machine tool for the different demands in the process of micro manufacturing. By contrast to traditional types of machine tools, the unique structure of reconfigurable machine tool makes it energy-saving, efficiently and the type of work can be rapidly changed in response to products change. The reconfigurable machine tool function can be switched between turning and milling with the exchange of mechanical units and modules. To ensure the high accuracy of this machine tool, the dynamic and static performance of turning unit and milling unit were analyzed with finite element method. The results of analysis were applied to make an optimized design parameters of machine tool. The desktop reconfigurable machine tool has a good structural performance according to the static and dynamic analysis results. The gantry type structure posses good scalability and it provides a flexible stage for the research of micro cutting.
This paper proposed the design of a desktop reconfigurable machine tool for the different demands in the process of micro manufacturing. By contrast to traditional types of machine tools, the unique structure of reconfigurable machine tool makes it energy-saving, efficiently and the type of work can be rapidly changed in response to products change. The reconfigurable machine tool function can be switched between turning and milling with the exchange of mechanical units and modules. To ensure the high accuracy of this machine tool, the dynamic and static performance of turning unit and milling unit were analyzed with finite element method. The results of analysis were applied to make an optimized design parameters of machine tool. The desktop reconfigurable machine tool has a good structural performance according to the static and dynamic analysis results. The gantry type structure posses good scalability and it provides a flexible stage for the research of micro cutting.
2015, 34(8): 1222-1228.
doi: 10.13433/j.cnki.1003-8728.2015.0815
Abstract:
An immune genetic algorithm for a large-scale job shop scheduling problem is proposed based on the Theory of Constraints (TOC). According to the theory, bottleneck mechanisms constrain the performance of a manufacturing system, so we use an immune genetic algorithm to encode the bottleneck mechanisms and non-bottleneck mechanisms respectively. The bottleneck mechanisms are scheduled deeply, and the non-bottleneck mechanisms are scheduled quickly to enhance the computational efficiency of the algorithm. To do so, we define a set of candidate bottleneck jobs and add them to the bottleneck mechanisms according to the TOC. The characteristic information on chromosomes is used to assist the optimization of the immune genetic algorithm with the operation of interchanging the sequences of the job shop scheduling problem on the bottleneck mechanisms. The simulation results show that the applications of bottleneck mechanisms and immune operators are effective, and the immune genetic algorithm can obtain satisfactory solutions within acceptable time.
An immune genetic algorithm for a large-scale job shop scheduling problem is proposed based on the Theory of Constraints (TOC). According to the theory, bottleneck mechanisms constrain the performance of a manufacturing system, so we use an immune genetic algorithm to encode the bottleneck mechanisms and non-bottleneck mechanisms respectively. The bottleneck mechanisms are scheduled deeply, and the non-bottleneck mechanisms are scheduled quickly to enhance the computational efficiency of the algorithm. To do so, we define a set of candidate bottleneck jobs and add them to the bottleneck mechanisms according to the TOC. The characteristic information on chromosomes is used to assist the optimization of the immune genetic algorithm with the operation of interchanging the sequences of the job shop scheduling problem on the bottleneck mechanisms. The simulation results show that the applications of bottleneck mechanisms and immune operators are effective, and the immune genetic algorithm can obtain satisfactory solutions within acceptable time.
2015, 34(8): 1229-1234.
doi: 10.13433/j.cnki.1003-8728.2015.0816
Abstract:
The lift platform cylinder hinge point location is analyzed. In order to improve the not so smooth lifting by the lift platform and to enlarge the piston thrust, the multi-objective optimization of the lift platform's piston thrust and lifting speed are carried out. Based on the kinematics and dynamics of the double-scissor hydraulic elevator, the mathematical models which set hydraulic piston thrust and hoisting speed as objectives are built. A few sets of different hydraulic cylinder hinge points are chosen to simulate and analyze the variation of piston thrust and lifting speed during lifting. Then the piston thrust and lifting speed as the objective are determined when the lift platform is at its lowest point. The particle swarm optimization algorithm was performed to optimize the hydraulic cylinder hinge point location, and MATLAB is used for programming and simulation. The algorithm is effective and can quickly and accurately obtain the optimal location parameters to achieve the whole elevator optimization.
The lift platform cylinder hinge point location is analyzed. In order to improve the not so smooth lifting by the lift platform and to enlarge the piston thrust, the multi-objective optimization of the lift platform's piston thrust and lifting speed are carried out. Based on the kinematics and dynamics of the double-scissor hydraulic elevator, the mathematical models which set hydraulic piston thrust and hoisting speed as objectives are built. A few sets of different hydraulic cylinder hinge points are chosen to simulate and analyze the variation of piston thrust and lifting speed during lifting. Then the piston thrust and lifting speed as the objective are determined when the lift platform is at its lowest point. The particle swarm optimization algorithm was performed to optimize the hydraulic cylinder hinge point location, and MATLAB is used for programming and simulation. The algorithm is effective and can quickly and accurately obtain the optimal location parameters to achieve the whole elevator optimization.
2015, 34(8): 1235-1238.
doi: 10.13433/j.cnki.1003-8728.2015.0817
Abstract:
In order to solve the CAD model reuse problem of machinery shell parts, in this paper, a analysis on geometry and structure characteristic of shell parts is made, and a method of constructing level of detail of machinery shell parts oriented to CAD model reuse is put forward. Firstly, we recognize the cutting loops of model in mixed areas model according to the BFS of oriented to collar. Secondly, the model is decomposed into multiple face shells along edges in the cutting loops, and finally through the construction of a 1EE or 2EE surface filling, the face shells are transformed into solids with shrinking the cutting loops and the decomposition results were stored as nodes in a CSG tree. After node simplification and deletion, the CSG tree was generated into LOD model. The experimental results which contain decomposition and the LOD model generating verify the effectiveness and correctness.
In order to solve the CAD model reuse problem of machinery shell parts, in this paper, a analysis on geometry and structure characteristic of shell parts is made, and a method of constructing level of detail of machinery shell parts oriented to CAD model reuse is put forward. Firstly, we recognize the cutting loops of model in mixed areas model according to the BFS of oriented to collar. Secondly, the model is decomposed into multiple face shells along edges in the cutting loops, and finally through the construction of a 1EE or 2EE surface filling, the face shells are transformed into solids with shrinking the cutting loops and the decomposition results were stored as nodes in a CSG tree. After node simplification and deletion, the CSG tree was generated into LOD model. The experimental results which contain decomposition and the LOD model generating verify the effectiveness and correctness.
2015, 34(8): 1239-1243.
doi: 10.13433/j.cnki.1003-8728.2015.0818
Abstract:
Because high-frequency chattering and poor tracking control performance exist in a direct drive bump-controlled electro-hydraulic position servo system when a common sliding mode control is used, we introduce a fuzzy control variable into the common sliding mode control to soften the control signal, thus weakening the severe chattering that arises from the sliding mode switching and improving the control precision and stability of the electro-hydraulic position servo system. The proportional switching fuzzy sliding mode controller is designed based on the above thought and is softened by its output. The simulation and experiments on the unit step response and cosine tracking characteristics have been carried out with the sliding mode control and fuzzy sliding mode control respectively. The results show that the fuzzy sliding mode control can remarkably increase the speed of dynamic response and steady-state control accuracy, enhance the robustness of the direct drive bump-controlled electro-hydraulic position servo system and weaken the high frequency chattering that exists in common sliding mode control.
Because high-frequency chattering and poor tracking control performance exist in a direct drive bump-controlled electro-hydraulic position servo system when a common sliding mode control is used, we introduce a fuzzy control variable into the common sliding mode control to soften the control signal, thus weakening the severe chattering that arises from the sliding mode switching and improving the control precision and stability of the electro-hydraulic position servo system. The proportional switching fuzzy sliding mode controller is designed based on the above thought and is softened by its output. The simulation and experiments on the unit step response and cosine tracking characteristics have been carried out with the sliding mode control and fuzzy sliding mode control respectively. The results show that the fuzzy sliding mode control can remarkably increase the speed of dynamic response and steady-state control accuracy, enhance the robustness of the direct drive bump-controlled electro-hydraulic position servo system and weaken the high frequency chattering that exists in common sliding mode control.
2015, 34(8): 1244-1247.
doi: 10.13433/j.cnki.1003-8728.2015.0819
Abstract:
In order to improve the flexibility and effectiveness of solder printing in the advanced microelectronic packaging, a micro droplet DOD generator driven by mechanical vibration was developed. It consisted of four components: the electromagnetic drive system, solder spray device, coaxial gas supply system and temperature control system. Micro droplets generating experiment was carried out with Sn-40wt. % Pb alloy. When the gas flow rate was between 7.5 L/min and 10 L/min, uniform solder particles with good sphericity were obtained. By adjusting the parameters of vibration, single droplet was generated stably. The experiment results also showed that the flying speed of droplet was about 2.43 m/s under the condition in present paper which was helpful for sufficient spread resulting in good printing quality. The research laid a foundation of high quality printing in the microelectronics packaging.
In order to improve the flexibility and effectiveness of solder printing in the advanced microelectronic packaging, a micro droplet DOD generator driven by mechanical vibration was developed. It consisted of four components: the electromagnetic drive system, solder spray device, coaxial gas supply system and temperature control system. Micro droplets generating experiment was carried out with Sn-40wt. % Pb alloy. When the gas flow rate was between 7.5 L/min and 10 L/min, uniform solder particles with good sphericity were obtained. By adjusting the parameters of vibration, single droplet was generated stably. The experiment results also showed that the flying speed of droplet was about 2.43 m/s under the condition in present paper which was helpful for sufficient spread resulting in good printing quality. The research laid a foundation of high quality printing in the microelectronics packaging.
Parametric Optimum Design of a Rocking Head Type Disc-shape Ultrasonic Motor Stator Based on OPTIMUS
2015, 34(8): 1248-1253.
doi: 10.13433/j.cnki.1003-8728.2015.0820
Abstract:
A parametric finite element model of the stator of a rocking head type disc-shape ultrasonic motor was built with the APDL in ANSYS software. Modal analysis, modal identification, node identification and harmonic response analysis of the stator were carried out based on this model. Then, the model is imported into the OPTIMUS software which is a multidisciplinary optimization platform. For dynamic optimization, the structure sizes were regarded as the optimization variables. Synthesized design requirements such as the operating frequency, model separation, amplitude of driving point and the stator clamping were considered to be the optimization objectives. Finally, a prototype of this USM was fabricated with the results of optimum design. The experimental results showed that the operating mode of the prototype meet the design requirements. Moreover, the experimental results were consistent with the optimized ones.
A parametric finite element model of the stator of a rocking head type disc-shape ultrasonic motor was built with the APDL in ANSYS software. Modal analysis, modal identification, node identification and harmonic response analysis of the stator were carried out based on this model. Then, the model is imported into the OPTIMUS software which is a multidisciplinary optimization platform. For dynamic optimization, the structure sizes were regarded as the optimization variables. Synthesized design requirements such as the operating frequency, model separation, amplitude of driving point and the stator clamping were considered to be the optimization objectives. Finally, a prototype of this USM was fabricated with the results of optimum design. The experimental results showed that the operating mode of the prototype meet the design requirements. Moreover, the experimental results were consistent with the optimized ones.
2015, 34(8): 1254-1258.
doi: 10.13433/j.cnki.1003-8728.2015.0821
Abstract:
This paper studied a choke valve for the MPD, simulated the flow field with the chamfered valve seat, combined theoretical derivation with field experiments to study the working mechanisms of the choke valve, and obtained the influence relations among opening degree, choke pressure and flow coefficient. The experimental results show that the choke valve can meet the control requirement that the pressure of the choke valve varies linearly with its opening degree and that the use of the chamfered valve seat guarantees the choke characteristics as well as mitigates the fluid medium scouring action on the choke valve, thus extending the life of the MPD choke valve.
This paper studied a choke valve for the MPD, simulated the flow field with the chamfered valve seat, combined theoretical derivation with field experiments to study the working mechanisms of the choke valve, and obtained the influence relations among opening degree, choke pressure and flow coefficient. The experimental results show that the choke valve can meet the control requirement that the pressure of the choke valve varies linearly with its opening degree and that the use of the chamfered valve seat guarantees the choke characteristics as well as mitigates the fluid medium scouring action on the choke valve, thus extending the life of the MPD choke valve.
2015, 34(8): 1259-1262.
doi: 10.13433/j.cnki.1003-8728.2015.0822
Abstract:
ANSYS software is used to simulate and analyze the stress of the membrane, then integration along the path of resistance to calculate the changes of resistance with the result stress date. Taguchi robust design method will be applied in the design of the sensor, and the effect factors and levels were determined with analyzing the parameters of varisitor size and location. The orthogonal experiment design and signal to noise ratio were calculated to carry out the robustness of parameters. Finally, the optimal combination of parameters is selected. This method can improve the performance and quality of the piezoresistive pressure sensor.
ANSYS software is used to simulate and analyze the stress of the membrane, then integration along the path of resistance to calculate the changes of resistance with the result stress date. Taguchi robust design method will be applied in the design of the sensor, and the effect factors and levels were determined with analyzing the parameters of varisitor size and location. The orthogonal experiment design and signal to noise ratio were calculated to carry out the robustness of parameters. Finally, the optimal combination of parameters is selected. This method can improve the performance and quality of the piezoresistive pressure sensor.
2015, 34(8): 1263-1266.
doi: 10.13433/j.cnki.1003-8728.2015.0823
Abstract:
The working principle of the tape machine and the structural design procedure of tape machine with the top-down design method of Pro/engineer's skeleton model are introduced. Multi-level skeleton and parallel skeleton are established in order to realize the transmission of design information. As the medium, the skeleton employs the publish geometry and copy geometry to guarantee the data's relevance of the assembly structure. The skeleton model promised the science of product design and the reliability of assemble. The design result indicated that the top-down design method can establish parallel processing systems expediently, realize parameterization and alteration of product quickly and synchronously, and improve design efficiency.
The working principle of the tape machine and the structural design procedure of tape machine with the top-down design method of Pro/engineer's skeleton model are introduced. Multi-level skeleton and parallel skeleton are established in order to realize the transmission of design information. As the medium, the skeleton employs the publish geometry and copy geometry to guarantee the data's relevance of the assembly structure. The skeleton model promised the science of product design and the reliability of assemble. The design result indicated that the top-down design method can establish parallel processing systems expediently, realize parameterization and alteration of product quickly and synchronously, and improve design efficiency.
2015, 34(8): 1267-1272.
doi: 10.13433/j.cnki.1003-8728.2015.0824
Abstract:
The approach of combining the numerical simulation and wind tunnel experiment was employed to study the effects of the body shape parameters on the aerodynamic drag reduction for non-smooth surface. This paper applied pit non-smooth surface to different locations of the international standard car model-Ahmed, and by analyzing the non-smooth drag reduction effects in different locations to determine where to add non-smooth surface. The variations of aerodynamic characteristics of non-smooth body were investigated and the optimum combination scheme for non-smooth aerodynamic shape was determined in case of changing the angle of the Ahmed model's rear window, front chamfer and road clearance. The results show that the size of the road clearance is the most influential one for non-smooth drag reduction, and 4.3% drag reduction rate can be reached.
The approach of combining the numerical simulation and wind tunnel experiment was employed to study the effects of the body shape parameters on the aerodynamic drag reduction for non-smooth surface. This paper applied pit non-smooth surface to different locations of the international standard car model-Ahmed, and by analyzing the non-smooth drag reduction effects in different locations to determine where to add non-smooth surface. The variations of aerodynamic characteristics of non-smooth body were investigated and the optimum combination scheme for non-smooth aerodynamic shape was determined in case of changing the angle of the Ahmed model's rear window, front chamfer and road clearance. The results show that the size of the road clearance is the most influential one for non-smooth drag reduction, and 4.3% drag reduction rate can be reached.
2015, 34(8): 1273-1278.
doi: 10.13433/j.cnki.1003-8728.2015.0825
Abstract:
The impact resistance of a car door trim is studied through experiment and finite element simulation. In order to meet higher performance requirements, the design of the foam structure is optimized based on the research result. Based on the related industry standards of China, the door trim collision regions relative to the occupant chest, abdomen and hip are determined; then the impactor is designed and manufactured, and the crashworthiness tests are conducted on the pendulum test bench. The finite element model of the door trim is established based on LS-DYNA and the model parameters of the main components are determined through experiments directly, then the crashworthiness analysis is undertaken with the established finite element model. The experimental results and simulation results are in good agreement. Based on the method of experimental design and the support vector machines, a surrogate model is established and structural optimization of the foam structure is done, the results show that the energy absorbed by the foam increases by 86.0%, energy absorbed by the door trim system increases by 42.2%.
The impact resistance of a car door trim is studied through experiment and finite element simulation. In order to meet higher performance requirements, the design of the foam structure is optimized based on the research result. Based on the related industry standards of China, the door trim collision regions relative to the occupant chest, abdomen and hip are determined; then the impactor is designed and manufactured, and the crashworthiness tests are conducted on the pendulum test bench. The finite element model of the door trim is established based on LS-DYNA and the model parameters of the main components are determined through experiments directly, then the crashworthiness analysis is undertaken with the established finite element model. The experimental results and simulation results are in good agreement. Based on the method of experimental design and the support vector machines, a surrogate model is established and structural optimization of the foam structure is done, the results show that the energy absorbed by the foam increases by 86.0%, energy absorbed by the door trim system increases by 42.2%.
2015, 34(8): 1279-1282.
doi: 10.13433/j.cnki.1003-8728.2015.0826
Abstract:
In order to ensure the biofidelity of a vehicle crash test dummy, it is essential to conduct a foot compression test. A compression testing machine was designed and manufactured based on the calibration test regulations for dummy foot. Four different elastic foam materials of heel pads with several thicknesses were made. Foot compression tests for these samples were performed. The influence of thickness, density and hardness of the sample on the mechanical responses was analyzed based on the test results. A general rule of stiffness curve changing with the thickness and hardness of the samples was obtained. The research results shows that a 6 mm or 7 mm heel pad foam sample with 10~20 Shore hardness (type C) is appropriate to ensure its biofidelity.
In order to ensure the biofidelity of a vehicle crash test dummy, it is essential to conduct a foot compression test. A compression testing machine was designed and manufactured based on the calibration test regulations for dummy foot. Four different elastic foam materials of heel pads with several thicknesses were made. Foot compression tests for these samples were performed. The influence of thickness, density and hardness of the sample on the mechanical responses was analyzed based on the test results. A general rule of stiffness curve changing with the thickness and hardness of the samples was obtained. The research results shows that a 6 mm or 7 mm heel pad foam sample with 10~20 Shore hardness (type C) is appropriate to ensure its biofidelity.
2015, 34(8): 1283-1288.
doi: 10.13433/j.cnki.1003-8728.2015.0827
Abstract:
Along rugged mountain roads or downhill roads, heavy-duty vehicles can achieve the purpose of stable driving with the constant torque braking of a hydraulic retarder. Considering the hydraulic retarder can produce high braking torque in a short time, we proposes a hydraulic control system to realize the constant torque braking. Because the hydraulic control system considers the liquid filling rate of the hydraulic retarder, its vent valve opening and cavity pressure, the hydraulic loss of the hydraulic retarder is reduced through hydrodynamic calculation. Besides, based on the vehicle braking and control simulation and the differential forward incremental PID (DFI-PID) simulation, the co-simulation of the control of the hydraulic retarder was carried out, thus obtaining the changes in vent valve opening and cavity pressure at higher liquid filling rate and then realizing the constant torque braking. The analysis results show that, during braking, at higher liquid filling rate, the vent valve opening needs to be adjusted to ensure that the hydraulic retarder has the constant torque braking of high strength.
Along rugged mountain roads or downhill roads, heavy-duty vehicles can achieve the purpose of stable driving with the constant torque braking of a hydraulic retarder. Considering the hydraulic retarder can produce high braking torque in a short time, we proposes a hydraulic control system to realize the constant torque braking. Because the hydraulic control system considers the liquid filling rate of the hydraulic retarder, its vent valve opening and cavity pressure, the hydraulic loss of the hydraulic retarder is reduced through hydrodynamic calculation. Besides, based on the vehicle braking and control simulation and the differential forward incremental PID (DFI-PID) simulation, the co-simulation of the control of the hydraulic retarder was carried out, thus obtaining the changes in vent valve opening and cavity pressure at higher liquid filling rate and then realizing the constant torque braking. The analysis results show that, during braking, at higher liquid filling rate, the vent valve opening needs to be adjusted to ensure that the hydraulic retarder has the constant torque braking of high strength.
2015, 34(8): 1289-1293.
doi: 10.13433/j.cnki.1003-8728.2015.0828
Abstract:
Combining the Direct Yaw Moment Control (DYC) and Active Front Steering (AFS) control, we proposed a vehicle stability integrated control method. Based on the vehicle nonlinear model, the phase plane of sideslip angle and sideslip angular velocity were used to determine the vehicle stability region. For the vehicle outside the stability region, the DYC was used to make the vehicle into the stability region. Then the AFS sliding mode control was used to make the vehicle sideslip angle and yaw rate track those of the ideal vehicle model. The simulation results and their analysis show that the integrated control method improves the stability of vehicle more effectively than separately with the AFS controller.
Combining the Direct Yaw Moment Control (DYC) and Active Front Steering (AFS) control, we proposed a vehicle stability integrated control method. Based on the vehicle nonlinear model, the phase plane of sideslip angle and sideslip angular velocity were used to determine the vehicle stability region. For the vehicle outside the stability region, the DYC was used to make the vehicle into the stability region. Then the AFS sliding mode control was used to make the vehicle sideslip angle and yaw rate track those of the ideal vehicle model. The simulation results and their analysis show that the integrated control method improves the stability of vehicle more effectively than separately with the AFS controller.
2015, 34(8): 1294-1297.
doi: 10.13433/j.cnki.1003-8728.2015.0829
Abstract:
This paper focuses on the E-glass/epoxy woven composite materials' progressive failure analysis and strength prediction. The model for the woven composites' macro-properties is obtained based on the micromechanics of composite materials and with homogenized method. This model also considers the damage criteria, and the material properties will be degraded and updated when damage occurs. This procedure is achieved by user material codes (ABAQUS.VUMAT). This model can easily trace the progressive failure behavior, predict failure strength, and finally obtain strain stress curves which can perfectly match experimental curves.
This paper focuses on the E-glass/epoxy woven composite materials' progressive failure analysis and strength prediction. The model for the woven composites' macro-properties is obtained based on the micromechanics of composite materials and with homogenized method. This model also considers the damage criteria, and the material properties will be degraded and updated when damage occurs. This procedure is achieved by user material codes (ABAQUS.VUMAT). This model can easily trace the progressive failure behavior, predict failure strength, and finally obtain strain stress curves which can perfectly match experimental curves.
2015, 34(8): 1298-1301.
doi: 10.13433/j.cnki.1003-8728.2015.0830
Abstract:
Fatigue life of butt-welded joint for high-strength steel widely used in engineering machinery, was investigated with the group method. Based on the mesh-insensitive structural stress method and main S-N curve method in american society of mechanical engineers(ASME) standard, fatigue life of the butt-welded joint for high-strength steel was predicted. The investigation showed that there exist some errors between the testing results and the prediction results which is based on the equivalent stress method. With the application of the modification master S-N curve formula according to pingsha dong equation, combining with the testing results, the modification factor was applied to the equivalent stress range( ΔSs) to get the modified main S-N curve, which can be applied for the prediction of fatigue life for high-strength steel.
Fatigue life of butt-welded joint for high-strength steel widely used in engineering machinery, was investigated with the group method. Based on the mesh-insensitive structural stress method and main S-N curve method in american society of mechanical engineers(ASME) standard, fatigue life of the butt-welded joint for high-strength steel was predicted. The investigation showed that there exist some errors between the testing results and the prediction results which is based on the equivalent stress method. With the application of the modification master S-N curve formula according to pingsha dong equation, combining with the testing results, the modification factor was applied to the equivalent stress range( ΔSs) to get the modified main S-N curve, which can be applied for the prediction of fatigue life for high-strength steel.
2015, 34(8): 1302-1307.
doi: 10.13433/j.cnki.1003-8728.2015.0831
Abstract:
Axial force, which induced by the interference-fit on the close contact interface between bolt and hole, is the crucial element to dominate the delamination of composite plate during the bolt insertion process. A model for predicting the axial force on the bolt insertion process of composite interference-fit joint is presented. According to the variation in contact field between bolt and hole, the insertion process has been divided into different stages and the mechanical behaviors have been analyzed. Based on the classical laminated plate theory and elastic mechanics method of complex variable function, the model for axial force during installing had been established. A 3D FEA simulation of bolt inserting process with interference-fit is conducted to verify the present model. The good correlation is observed between the FEA and the model in various interference-fit.
Axial force, which induced by the interference-fit on the close contact interface between bolt and hole, is the crucial element to dominate the delamination of composite plate during the bolt insertion process. A model for predicting the axial force on the bolt insertion process of composite interference-fit joint is presented. According to the variation in contact field between bolt and hole, the insertion process has been divided into different stages and the mechanical behaviors have been analyzed. Based on the classical laminated plate theory and elastic mechanics method of complex variable function, the model for axial force during installing had been established. A 3D FEA simulation of bolt inserting process with interference-fit is conducted to verify the present model. The good correlation is observed between the FEA and the model in various interference-fit.
2015, 34(8): 1308-1312.
doi: 10.13433/j.cnki.1003-8728.2015.0832
Abstract:
To describe the characteristic of human factors in aircraft control wheel design with a theoretically and standardized approach, the civilian aircraft control wheel design was conducted with the consideration of human factors based on Ergonomic theory and CATIA kinematics simulation. The key points for the use of human factors in control wheel general design, precise design and switch disposal were introduced in details. The human factor characteristics in control wheel design of some typical aircrafts were compared and analyzed with illustration to further prove the importance of human factor. It is demonstrated that high score (2.5 to 3) was obtained from experienced pilots based on an international evaluation table Cooper-Harper evaluated in actually operating condition and the correctness and rationality of our viewpoints was validated. The human factor characteristic data and standard that we explored should be considered important in civilian aircraft wheel design.
To describe the characteristic of human factors in aircraft control wheel design with a theoretically and standardized approach, the civilian aircraft control wheel design was conducted with the consideration of human factors based on Ergonomic theory and CATIA kinematics simulation. The key points for the use of human factors in control wheel general design, precise design and switch disposal were introduced in details. The human factor characteristics in control wheel design of some typical aircrafts were compared and analyzed with illustration to further prove the importance of human factor. It is demonstrated that high score (2.5 to 3) was obtained from experienced pilots based on an international evaluation table Cooper-Harper evaluated in actually operating condition and the correctness and rationality of our viewpoints was validated. The human factor characteristic data and standard that we explored should be considered important in civilian aircraft wheel design.
