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RSS2016 Vol. 35, No. 2
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2016, 35(2): 165-170.
doi: 10.13433/j.cnki.1003-8728.2016.0201
PDF 991KB
Abstract:
Gear pump has been developed with high pressure and large flow, where the work efficiency is highly required. Clearance leakage, viscous friction and flow pulsation directly affect efficiency of pump. One of the characteristics of large flow gear pump is large module, relatively few teeth, large tooth height and tooth thickness, which result the loss increase of clearance leakage and viscous friction, especially viscous friction loss. Aiming at the characteristics of large module and few teeth of high pressure and large flow gear pumps, the concept of general efficiency of the gear pump is presented in this paper and the optimization model associated with general efficiency is established. The structure of the gear parameters is optimized by using Sequential Quadratic Programming (SQP) to solve the difficulty caused by rounding method. The Efficiency-improving design of high pressure and large flow gear pump by using hybrid parameters is realized.
Gear pump has been developed with high pressure and large flow, where the work efficiency is highly required. Clearance leakage, viscous friction and flow pulsation directly affect efficiency of pump. One of the characteristics of large flow gear pump is large module, relatively few teeth, large tooth height and tooth thickness, which result the loss increase of clearance leakage and viscous friction, especially viscous friction loss. Aiming at the characteristics of large module and few teeth of high pressure and large flow gear pumps, the concept of general efficiency of the gear pump is presented in this paper and the optimization model associated with general efficiency is established. The structure of the gear parameters is optimized by using Sequential Quadratic Programming (SQP) to solve the difficulty caused by rounding method. The Efficiency-improving design of high pressure and large flow gear pump by using hybrid parameters is realized.
2016, 35(2): 171-175.
doi: 10.13433/j.cnki.1003-8728.2016.0202
Abstract:
In order to acquire the contact force between balls and central rail, the ADAMS software was utilized to perform the dynamic simulation for the multi-contact problem of central rail and balls based on impact function method. The dw8 ball which experienced the maximum contact force was chosen as the research model for the case that the central rail was subjected to tension. Contact stress parameters were obtained with a contact model established in ABAQUS software. It can be concluded that:1) When a central rail is being pushed or pulled, the alternative contact stress will exist on both upper and lower surfaces of the central rail and the stress amplitude is larger than that on the ball, which makes the surface of central rails be prone to contact fatigue damage; 2) The amplitude of Von Mises stress is firstly increased and then decreased from the inner to the outer, and the maximum amplitude occurrs slightly below the contact surface, which explains the reason why the fatigue cracks usually forms inside of the contact body and slowly extends to the surface. The simulation test and conclusions provide useful results for future study of the durability design of flexballs.
In order to acquire the contact force between balls and central rail, the ADAMS software was utilized to perform the dynamic simulation for the multi-contact problem of central rail and balls based on impact function method. The dw8 ball which experienced the maximum contact force was chosen as the research model for the case that the central rail was subjected to tension. Contact stress parameters were obtained with a contact model established in ABAQUS software. It can be concluded that:1) When a central rail is being pushed or pulled, the alternative contact stress will exist on both upper and lower surfaces of the central rail and the stress amplitude is larger than that on the ball, which makes the surface of central rails be prone to contact fatigue damage; 2) The amplitude of Von Mises stress is firstly increased and then decreased from the inner to the outer, and the maximum amplitude occurrs slightly below the contact surface, which explains the reason why the fatigue cracks usually forms inside of the contact body and slowly extends to the surface. The simulation test and conclusions provide useful results for future study of the durability design of flexballs.
Application of the Modified Response Surface Method to Reliability Optimization Design of Gun Barrel
2016, 35(2): 176-181.
doi: 10.13433/j.cnki.1003-8728.2016.0203
Abstract:
For a certain kind of gun barrel, a modified response surface method to study the reliability optimization design is proposed. To combine Genetic algorithm (GA) and Gauss-Newton method (GNM) is used to acquire the optimal solutions of the model parameters. Firstly, GA is used to solve the initial values of the model parameters. Secondly, GNM is used to get the optimal solution according to the initial values. At last, the reliability optimization design with the agent model can be done. GA is an effective in global solution space searching, while GNM is an effective in local searching. The simulation result shows that the combination of GA and GNM obtains a higher precision of ablation estimation and greatly improves the computational efficiency in the optimization of gun barrel ablation life as well.
For a certain kind of gun barrel, a modified response surface method to study the reliability optimization design is proposed. To combine Genetic algorithm (GA) and Gauss-Newton method (GNM) is used to acquire the optimal solutions of the model parameters. Firstly, GA is used to solve the initial values of the model parameters. Secondly, GNM is used to get the optimal solution according to the initial values. At last, the reliability optimization design with the agent model can be done. GA is an effective in global solution space searching, while GNM is an effective in local searching. The simulation result shows that the combination of GA and GNM obtains a higher precision of ablation estimation and greatly improves the computational efficiency in the optimization of gun barrel ablation life as well.
2016, 35(2): 182-186.
doi: 10.13433/j.cnki.1003-8728.2016.0204
Abstract:
For the character of the high moment of inertia, high movement speed and high precision of the moving target simulator, with servo system as the research object, considering the factor of high moment of inertia, with the research focus of fast running system, output of actuator strictly following reference input of control system, and reducing contour error, the servo system is designed. The control model of moving target simulator servo system is built. The cross-coupling control system is introduced into the moving target simulator servo control system and the servo system is verified by using MATLAB simulation.
For the character of the high moment of inertia, high movement speed and high precision of the moving target simulator, with servo system as the research object, considering the factor of high moment of inertia, with the research focus of fast running system, output of actuator strictly following reference input of control system, and reducing contour error, the servo system is designed. The control model of moving target simulator servo system is built. The cross-coupling control system is introduced into the moving target simulator servo control system and the servo system is verified by using MATLAB simulation.
2016, 35(2): 187-191.
doi: 10.13433/j.cnki.1003-8728.2016.0205
Abstract:
Sink roll device is a key functional component of zinc pot of hot dip galvanized line. To study the influential factors on vibration inherent characteristics of sink roll device, this paper carries out the wet modal analysis and the prestressed modal analysis of sink roll device based on finite element method and mathematical models. The effects of fluid density, strip section and its tension on the sink roll device of vibration frequency and regularity are studied, and the cause of the difference of frequency is analyzed. The results show that, sink roll device vibration in liquid zinc is reduced when the frequency ratio of 24.4%~58.8% in the air, and the natural frequencies of fluid density decrease with increasing. The sink roll device in strip section and tension prestressed loads has little effect on the natural frequency, but some of the asymmetry of the natural mode of vibration will reduce the bearing service life.
Sink roll device is a key functional component of zinc pot of hot dip galvanized line. To study the influential factors on vibration inherent characteristics of sink roll device, this paper carries out the wet modal analysis and the prestressed modal analysis of sink roll device based on finite element method and mathematical models. The effects of fluid density, strip section and its tension on the sink roll device of vibration frequency and regularity are studied, and the cause of the difference of frequency is analyzed. The results show that, sink roll device vibration in liquid zinc is reduced when the frequency ratio of 24.4%~58.8% in the air, and the natural frequencies of fluid density decrease with increasing. The sink roll device in strip section and tension prestressed loads has little effect on the natural frequency, but some of the asymmetry of the natural mode of vibration will reduce the bearing service life.
2016, 35(2): 192-195.
doi: 10.13433/j.cnki.1003-8728.2016.0206
Abstract:
A de-noising method based on compressed sensing is proposed for rolling bearing signal with noise. This method can adaptively select the threshold according to the distribution of DCT (Discrete Cosine Transform) transform coefficients. The signal is reconstructed using the modified OMP (Orthogonal Matching Pursuit) by threshold to realize de-noising. Experimental results and their analysis show preliminarily that:in comparison with the wavelet methods, this method is close to hyperbolic threshold methods, and better than soft threshold methods, while the amount of data and the processing is much smaller than the wavelet methods.
A de-noising method based on compressed sensing is proposed for rolling bearing signal with noise. This method can adaptively select the threshold according to the distribution of DCT (Discrete Cosine Transform) transform coefficients. The signal is reconstructed using the modified OMP (Orthogonal Matching Pursuit) by threshold to realize de-noising. Experimental results and their analysis show preliminarily that:in comparison with the wavelet methods, this method is close to hyperbolic threshold methods, and better than soft threshold methods, while the amount of data and the processing is much smaller than the wavelet methods.
2016, 35(2): 196-202.
doi: 10.13433/j.cnki.1003-8728.2016.0207
Abstract:
The non-Gaussian random loading is complicated to characterize. In this study, the displacement response of the cantilever beam under the single-point non-Gaussian excitation is investigated. Firstly, the statistical characteristics and spectral properties are analyzed qualitatively, and it shows that the spectral method based on power spectrum is not quite suitable for non-Gaussian process and it is difficult to apply the method based on higher-order spectrum in the response analysis. Secondly, the time-domain formulae for the response analysis of a cantilever beam excited by non-Gaussian input are established. Then the factors that will affect the kurtosis value of the displacement response are determined. Finally, the influence of the excitation point, steady properties and damping ratio to the kurtosis value is examined by numerical simulations.
The non-Gaussian random loading is complicated to characterize. In this study, the displacement response of the cantilever beam under the single-point non-Gaussian excitation is investigated. Firstly, the statistical characteristics and spectral properties are analyzed qualitatively, and it shows that the spectral method based on power spectrum is not quite suitable for non-Gaussian process and it is difficult to apply the method based on higher-order spectrum in the response analysis. Secondly, the time-domain formulae for the response analysis of a cantilever beam excited by non-Gaussian input are established. Then the factors that will affect the kurtosis value of the displacement response are determined. Finally, the influence of the excitation point, steady properties and damping ratio to the kurtosis value is examined by numerical simulations.
2016, 35(2): 203-209.
doi: 10.13433/j.cnki.1003-8728.2016.0208
Abstract:
Due to the complexity of PDC (polycrystalline diamond compact) bits' geometry, rock materials and a downhole's working conditions, its cutting rock breaking mechanism has always been a puzzle. Using the single tooth cutting mechanism and introducing the specific energy ε of rock, we find the relationship among Weight On Bit (WOB) w, torque t and cutting depth d and establish the two-dimensional diagram (E-S) between cutting specific energy (E) and drilling strength (S). The concept model of rock fragmentation is elaborated by using the frictional component. The 3D non-linear dynamic model of dynamic rock breaking with a full-gauge PDC bit is established with the finite element method, which can be used to further analyze the response of rock-breaking processes of the PDC drill bit. The analysis results show that the rock damage and the stress cloud can directly reflect the wellbore formation following the peeling of the damaged rock and the stress distribution of the downhole during the drilling process. The displacement, acceleration and torque responses of the PDC drill bit in its drilling direction well coincide with the theoretical analysis and not only interpret the "footage step" in the drilling process but also evidence the conceptual model of the rock breaking process.
Due to the complexity of PDC (polycrystalline diamond compact) bits' geometry, rock materials and a downhole's working conditions, its cutting rock breaking mechanism has always been a puzzle. Using the single tooth cutting mechanism and introducing the specific energy ε of rock, we find the relationship among Weight On Bit (WOB) w, torque t and cutting depth d and establish the two-dimensional diagram (E-S) between cutting specific energy (E) and drilling strength (S). The concept model of rock fragmentation is elaborated by using the frictional component. The 3D non-linear dynamic model of dynamic rock breaking with a full-gauge PDC bit is established with the finite element method, which can be used to further analyze the response of rock-breaking processes of the PDC drill bit. The analysis results show that the rock damage and the stress cloud can directly reflect the wellbore formation following the peeling of the damaged rock and the stress distribution of the downhole during the drilling process. The displacement, acceleration and torque responses of the PDC drill bit in its drilling direction well coincide with the theoretical analysis and not only interpret the "footage step" in the drilling process but also evidence the conceptual model of the rock breaking process.
2016, 35(2): 210-215.
doi: 10.13433/j.cnki.1003-8728.2016.0209
Abstract:
Comparing with conventional theoretical and experimental approaches, the numerical simulation method is faster to obtain the inside flow field distribution of centrifugal pumps. This can be used as references in centrifugal pump design. Thus, the numerical method on flow field in centrifugal pump was explored in this article. Geometry model was built and unstructured meshes were generated. Numerical simulation was adopted by solving the Reynolds Average Navier-Stokes (RANS) equation with CFX software. Total head and efficiency of centrifugal pump under different working conditions were calculated. The simulation results and measured data were compared; the relative error of total head is 2.8% while the error of efficiency is 1.8% at designed working point Q. Thus, the numerical method for whole flow field of centrifugal pump built in this article is reliable; it can predict and analyze the performance of centrifugal pumps rapidly and accurately.
Comparing with conventional theoretical and experimental approaches, the numerical simulation method is faster to obtain the inside flow field distribution of centrifugal pumps. This can be used as references in centrifugal pump design. Thus, the numerical method on flow field in centrifugal pump was explored in this article. Geometry model was built and unstructured meshes were generated. Numerical simulation was adopted by solving the Reynolds Average Navier-Stokes (RANS) equation with CFX software. Total head and efficiency of centrifugal pump under different working conditions were calculated. The simulation results and measured data were compared; the relative error of total head is 2.8% while the error of efficiency is 1.8% at designed working point Q. Thus, the numerical method for whole flow field of centrifugal pump built in this article is reliable; it can predict and analyze the performance of centrifugal pumps rapidly and accurately.
2016, 35(2): 216-221.
doi: 10.13433/j.cnki.1003-8728.2016.0210
Abstract:
A high-precision micro-manipulation stage with two-level amplifer was presented, which dynamic model was driven by PZT actuator, and PID control strategy was adopted to trade off its characteristics. With two-level amplification mechanism, the stage is designed into a symmetrical structure in order to improve the motion accuracy. The finite element method and the modal truncation method are used to build the transfer function of the stage which can be modeled as a mass-spring-damper system. The electrical properties of PZT actuator is equivalent to the RC circuit, and the mechanical properties is equivalent to the device with a certain flexibility. Thus, the open-loop and closed-loop transfers of the whole system can be obtained. The PID controller is designed for the purpose of balancing the dynamic performance and stability of the system. The analysis results showed that the phase and gain margin of the system can increase, and the steady performance can be improved under the PID controller. But the cut-off frequency decreases, and the rapid response is slowed down. Meanwhile, the settling time and overshoot of the system can be reduced to improve the system stability. The time constant of the actuator has a great effect on the dynamic performance of the micro-manipulation stage, and when the time constant is around 0.2 ms, the smaller settling time and suitable overshoot can be obtained.
A high-precision micro-manipulation stage with two-level amplifer was presented, which dynamic model was driven by PZT actuator, and PID control strategy was adopted to trade off its characteristics. With two-level amplification mechanism, the stage is designed into a symmetrical structure in order to improve the motion accuracy. The finite element method and the modal truncation method are used to build the transfer function of the stage which can be modeled as a mass-spring-damper system. The electrical properties of PZT actuator is equivalent to the RC circuit, and the mechanical properties is equivalent to the device with a certain flexibility. Thus, the open-loop and closed-loop transfers of the whole system can be obtained. The PID controller is designed for the purpose of balancing the dynamic performance and stability of the system. The analysis results showed that the phase and gain margin of the system can increase, and the steady performance can be improved under the PID controller. But the cut-off frequency decreases, and the rapid response is slowed down. Meanwhile, the settling time and overshoot of the system can be reduced to improve the system stability. The time constant of the actuator has a great effect on the dynamic performance of the micro-manipulation stage, and when the time constant is around 0.2 ms, the smaller settling time and suitable overshoot can be obtained.
2016, 35(2): 222-226.
doi: 10.13433/j.cnki.1003-8728.2016.0211
Abstract:
Aim at the unidirectional penalty treatment of intermediate density elements in traditional topology optimization, a Bi-Directional Interpolation Model (BDIM) decided by a threshold is presented to treat the intermediate density elements. Then the mathematical model of topology optimization is established based on the proposed model. Example optimization are performed with gradient projection method, and the results obtained by using the traditional interpolation model、BDIM only for sensitivity and BDIM for sensitivity and rigidity, respectively, are compared, it is found that the BDIM only for sensitivity can get a global convergence and clear boundaries optimization results.
Aim at the unidirectional penalty treatment of intermediate density elements in traditional topology optimization, a Bi-Directional Interpolation Model (BDIM) decided by a threshold is presented to treat the intermediate density elements. Then the mathematical model of topology optimization is established based on the proposed model. Example optimization are performed with gradient projection method, and the results obtained by using the traditional interpolation model、BDIM only for sensitivity and BDIM for sensitivity and rigidity, respectively, are compared, it is found that the BDIM only for sensitivity can get a global convergence and clear boundaries optimization results.
2016, 35(2): 227-231.
doi: 10.13433/j.cnki.1003-8728.2016.0212
Abstract:
The theory of plates and shells is not adapted to design thickness of shell structure in engineering due to complexity. An optimum design method based on the finite element method is presented. Firstly, a mathematical model based on the theory of plates and shells and the finite element method is established, and then an optimum design method for thickness of complex shells based on ANSYS is proposed. Furthermore, the influences of the load, constraint and complexity on the design error are analyzed; the analysis results indicate that the proposed method can be applied to the complex loads, different constraint types, different load types and complex structural model. Finally, an optimal design example is illustrated, which demonstrates that the proposed design method is effective and feasible.
The theory of plates and shells is not adapted to design thickness of shell structure in engineering due to complexity. An optimum design method based on the finite element method is presented. Firstly, a mathematical model based on the theory of plates and shells and the finite element method is established, and then an optimum design method for thickness of complex shells based on ANSYS is proposed. Furthermore, the influences of the load, constraint and complexity on the design error are analyzed; the analysis results indicate that the proposed method can be applied to the complex loads, different constraint types, different load types and complex structural model. Finally, an optimal design example is illustrated, which demonstrates that the proposed design method is effective and feasible.
2016, 35(2): 232-236.
doi: 10.13433/j.cnki.1003-8728.2016.0213
Abstract:
Various uncertain factors affect movement of manipulator, thus the end-effector tends to deviate from the theoretical position resulting in lower working accuracy, in which the joint clearance have an significant effect on the movement of manipulator. In order to study the influence of joint clearance to the pose accuracy of end-effector, the inverse kinematics mathematical model of the manipulator was established by D-H coordinate and coordinate transfer matrix method, getting the generalized coordinate equations with MATLAB, based on the present forward kinematics model; SolidWorks was used to establish the manipulator models and make error analysis and computer simulations of the manipulator with joint clearance and no joint clearance. At last, the movement characteristic of the end-effector is attained. The results and their analysis show preliminarily that the joint clearance has a certain effect on the linear motion characteristic and the angular acceleration, especially the linear acceleration and angular acceleration, which makes the pose of end-effector deviation, and reduces the motion stability and operation accuracy.
Various uncertain factors affect movement of manipulator, thus the end-effector tends to deviate from the theoretical position resulting in lower working accuracy, in which the joint clearance have an significant effect on the movement of manipulator. In order to study the influence of joint clearance to the pose accuracy of end-effector, the inverse kinematics mathematical model of the manipulator was established by D-H coordinate and coordinate transfer matrix method, getting the generalized coordinate equations with MATLAB, based on the present forward kinematics model; SolidWorks was used to establish the manipulator models and make error analysis and computer simulations of the manipulator with joint clearance and no joint clearance. At last, the movement characteristic of the end-effector is attained. The results and their analysis show preliminarily that the joint clearance has a certain effect on the linear motion characteristic and the angular acceleration, especially the linear acceleration and angular acceleration, which makes the pose of end-effector deviation, and reduces the motion stability and operation accuracy.
2016, 35(2): 237-240.
doi: 10.13433/j.cnki.1003-8728.2016.0214
Abstract:
Fetching carton is one of the most important parts in the square carpets packaging. In order to successfully catch up every carpet carton and move it to the expected location, in this study, an adjustable double parallelogram mechanism whose actuator is air cylinder is designed as the fetching carton mechanism of square carpets packing machine, the kinematics model of mechanism is established and its kinematics character is analyzed. The results show that the designed mechanism not only has the advantages of reasonable structure, reliable motion but also have a strong practicality, which can satisfy the packing requirements of square carpets packing machine.
Fetching carton is one of the most important parts in the square carpets packaging. In order to successfully catch up every carpet carton and move it to the expected location, in this study, an adjustable double parallelogram mechanism whose actuator is air cylinder is designed as the fetching carton mechanism of square carpets packing machine, the kinematics model of mechanism is established and its kinematics character is analyzed. The results show that the designed mechanism not only has the advantages of reasonable structure, reliable motion but also have a strong practicality, which can satisfy the packing requirements of square carpets packing machine.
2016, 35(2): 241-246.
doi: 10.13433/j.cnki.1003-8728.2016.0215
Abstract:
To meet the requirements of better static-dynamic characteristics and lower weight for an industrial robot's arm, we use the SIMP(Solid Isotropic Microstructures with Penalization) topological optimization method the relative difference method to establish the mathematical model of the multi-objective topological optimization. We regard the improving stiffness under multi-conditions and natural frequencies as static and dynamic objectives. We study the L-shape arm of the MOTOMAN-HP20 industrial robot and optimize its static-dynamic topology, thus obtaining the new structure of the L-shape arm. The comparative analysis shows that both the stiffness of the L-shape arm under multi-conditions and its natural frequencies are improved, and that its weight decreases by 15.5%. The problem that the high order of magnitude dominates the multi-objective optimization results was solved by adopting the relative difference method.
To meet the requirements of better static-dynamic characteristics and lower weight for an industrial robot's arm, we use the SIMP(Solid Isotropic Microstructures with Penalization) topological optimization method the relative difference method to establish the mathematical model of the multi-objective topological optimization. We regard the improving stiffness under multi-conditions and natural frequencies as static and dynamic objectives. We study the L-shape arm of the MOTOMAN-HP20 industrial robot and optimize its static-dynamic topology, thus obtaining the new structure of the L-shape arm. The comparative analysis shows that both the stiffness of the L-shape arm under multi-conditions and its natural frequencies are improved, and that its weight decreases by 15.5%. The problem that the high order of magnitude dominates the multi-objective optimization results was solved by adopting the relative difference method.
2016, 35(2): 247-252.
doi: 10.13433/j.cnki.1003-8728.2016.0216
Abstract:
The CNC machine tool was divided into main systems and auxiliary systems according to its functional hierarchy. The relationship between main systems and auxiliary systems was researched, the reliability modeling technology of superelement was proposed, the auxiliary systems were embedded into the reliability mathematic model of main systems in the form of superelement, and a dynamic reliability analysis model of CNC machine subsystems based on Markov process was established, which reduced the state space of the system. Based on these, assuming that each main system is the independent model, the steady reliability index of the CNC machine was calculated with Kronecker method. Finally, a case of CNC cylindrical grinding machine was given, with its reliability analyzed by solving the reliability index of the actual data; therefore, the result demonstrated the correctness and applicability of the model.
The CNC machine tool was divided into main systems and auxiliary systems according to its functional hierarchy. The relationship between main systems and auxiliary systems was researched, the reliability modeling technology of superelement was proposed, the auxiliary systems were embedded into the reliability mathematic model of main systems in the form of superelement, and a dynamic reliability analysis model of CNC machine subsystems based on Markov process was established, which reduced the state space of the system. Based on these, assuming that each main system is the independent model, the steady reliability index of the CNC machine was calculated with Kronecker method. Finally, a case of CNC cylindrical grinding machine was given, with its reliability analyzed by solving the reliability index of the actual data; therefore, the result demonstrated the correctness and applicability of the model.
2016, 35(2): 253-259.
doi: 10.13433/j.cnki.1003-8728.2016.0217
Abstract:
A novel additive manufacturing equipment built on CNC in an environmentally friendly fashion has been developed for manufacturing three dimensional ceramic components, on which a high solid ceramic colloidal paste below the temperature of solidification point is deposited layer-by-layer by extruding an aqueous. Due to the release of the bubble, the formation of agglomeration, the breakdown of material agglomeration and reducing of material in stocker at the deposition process of three dimensional components, the extrusion force of deposition process is changed with the ceramic paste status and the deposition process is unstable, therefore, the quality of deposited parts is hardly guaranteed. Analyzing on the various process parameters and disturbance affected on the deposition process of ceramic-based components, based on the plentiful of experiments, the dynamic model for deposition process is constructed in this paper and the recursive least squares (RLS) method is used to systematiccly identify, the adaptive extrusion force controller is designed to conduct the experiment and simulation of freeze deposition process. The results demonstrate that the dynamic model can effectively describe the extrusion force change in the freeze deposition process and the adaptive controller can well track the different kind of reference extrusion force and promote stability in the deposition process of three dimensional components.
A novel additive manufacturing equipment built on CNC in an environmentally friendly fashion has been developed for manufacturing three dimensional ceramic components, on which a high solid ceramic colloidal paste below the temperature of solidification point is deposited layer-by-layer by extruding an aqueous. Due to the release of the bubble, the formation of agglomeration, the breakdown of material agglomeration and reducing of material in stocker at the deposition process of three dimensional components, the extrusion force of deposition process is changed with the ceramic paste status and the deposition process is unstable, therefore, the quality of deposited parts is hardly guaranteed. Analyzing on the various process parameters and disturbance affected on the deposition process of ceramic-based components, based on the plentiful of experiments, the dynamic model for deposition process is constructed in this paper and the recursive least squares (RLS) method is used to systematiccly identify, the adaptive extrusion force controller is designed to conduct the experiment and simulation of freeze deposition process. The results demonstrate that the dynamic model can effectively describe the extrusion force change in the freeze deposition process and the adaptive controller can well track the different kind of reference extrusion force and promote stability in the deposition process of three dimensional components.
2016, 35(2): 260-266.
doi: 10.13433/j.cnki.1003-8728.2016.0218
Abstract:
Contraposed the vibrational impacts on the cutting process efficiency and quality in the turning of nickel-based superalloy GH4169, a method was presented for valid judgment of cutting condition which is according to the cutting parameter. The two-degrees-freedom turning vibration model was primarily established. Then the test of modal analysis was conducted by hammering method for numerical control lathe tool system, the parameters such as the first frequency, modal damping, modal stiffness, modal mass and so on had been measured. The model to simulate the cutting process was designed based on MATLAB/Simulink platform. The stable limit cutting depth and main vibration direction of the flutter were predicted according to the simulation results. At last, the experiment of varying cutting depth was carried out with PCBN tool which verified the correction of simulation. To sum up, the simulation model has certain references in the prediction of the regenerative chatter and the optimization of cutting process for nickel-based superalloy GH4169.
Contraposed the vibrational impacts on the cutting process efficiency and quality in the turning of nickel-based superalloy GH4169, a method was presented for valid judgment of cutting condition which is according to the cutting parameter. The two-degrees-freedom turning vibration model was primarily established. Then the test of modal analysis was conducted by hammering method for numerical control lathe tool system, the parameters such as the first frequency, modal damping, modal stiffness, modal mass and so on had been measured. The model to simulate the cutting process was designed based on MATLAB/Simulink platform. The stable limit cutting depth and main vibration direction of the flutter were predicted according to the simulation results. At last, the experiment of varying cutting depth was carried out with PCBN tool which verified the correction of simulation. To sum up, the simulation model has certain references in the prediction of the regenerative chatter and the optimization of cutting process for nickel-based superalloy GH4169.
2016, 35(2): 267-272.
doi: 10.13433/j.cnki.1003-8728.2016.0219
Abstract:
Through-mask electrochemical micromachining (TM-EMM) is an effective method for surface texturing of metal substrate. To fabricate the microstructure array on the inner surface of bushing, the simulations and experiments for TM-EMM have been conducted. The finite element model has been built and the influence laws and mechanisms of pattern distribution nonuniformity and mask thickness on the current density distribution have been investigated. The numerical calculation results show that adoption of the all-in-one style of mask and cathode facilitates more uniform etched depth for machining on surface with nonuniform pattern distribution and the bottom topography of etched microstructure can be regulated by regulating the ratio of mask thickness and patter size. Based on the simulation results, machining parameters optimization have been experimentally conducted and the micro-pits with a diameter of 100μm have successfully fabricated under the optimized conditions.
Through-mask electrochemical micromachining (TM-EMM) is an effective method for surface texturing of metal substrate. To fabricate the microstructure array on the inner surface of bushing, the simulations and experiments for TM-EMM have been conducted. The finite element model has been built and the influence laws and mechanisms of pattern distribution nonuniformity and mask thickness on the current density distribution have been investigated. The numerical calculation results show that adoption of the all-in-one style of mask and cathode facilitates more uniform etched depth for machining on surface with nonuniform pattern distribution and the bottom topography of etched microstructure can be regulated by regulating the ratio of mask thickness and patter size. Based on the simulation results, machining parameters optimization have been experimentally conducted and the micro-pits with a diameter of 100μm have successfully fabricated under the optimized conditions.
2016, 35(2): 273-278.
doi: 10.13433/j.cnki.1003-8728.2016.0220
Abstract:
In order to solve the problems of complex operation and low modeling accuracy in the process of 3D modeling for the modification of gear tooth, the analytical equations of topological tooth surface were deduced for cylindrical helical gear with profile modification and lead modification based on the principle of gear geometry. The topological gear tooth surfaces were represented by the numerical simulation method. The method of spline curves scanning and reverse engineering in the software of CATIA V5 R20 were applied to establish the 3D modeling for modified tooth. The accuracy estimation for modeling the tooth profile and lead modification was evaluated according to the AGMA standard. The results show that modeling accuracy grade of 0 for the reverse engineering method of the tooth surface reconstructed can be obtained.
In order to solve the problems of complex operation and low modeling accuracy in the process of 3D modeling for the modification of gear tooth, the analytical equations of topological tooth surface were deduced for cylindrical helical gear with profile modification and lead modification based on the principle of gear geometry. The topological gear tooth surfaces were represented by the numerical simulation method. The method of spline curves scanning and reverse engineering in the software of CATIA V5 R20 were applied to establish the 3D modeling for modified tooth. The accuracy estimation for modeling the tooth profile and lead modification was evaluated according to the AGMA standard. The results show that modeling accuracy grade of 0 for the reverse engineering method of the tooth surface reconstructed can be obtained.
2016, 35(2): 279-284.
doi: 10.13433/j.cnki.1003-8728.2016.0221
Abstract:
In order to accurately obtain the failure characteristics of a reciprocating pump so as to monitor and diagnose its working conditions, this article artificially simulated 6 kinds of typical failure at its hydraulic end such as the leakage of pump valve, spring break, plunger wear, obtaining the indicator diagram and law of the reciprocating pump under typical fault conditions. It extracted the feature of its gray matrix based on the indicator diagram and then pretreated them to extract 6 groups of characteristics with the MATLAB. The results obtained with support vector machine trained sample data show that the automatic fault recognition rate of the method reaches more than 95%, having a higher diagnostic accuracy. Therefore the method can be used to establish the automatic online monitoring and fault diagnosis data base of a reciprocating pump.
In order to accurately obtain the failure characteristics of a reciprocating pump so as to monitor and diagnose its working conditions, this article artificially simulated 6 kinds of typical failure at its hydraulic end such as the leakage of pump valve, spring break, plunger wear, obtaining the indicator diagram and law of the reciprocating pump under typical fault conditions. It extracted the feature of its gray matrix based on the indicator diagram and then pretreated them to extract 6 groups of characteristics with the MATLAB. The results obtained with support vector machine trained sample data show that the automatic fault recognition rate of the method reaches more than 95%, having a higher diagnostic accuracy. Therefore the method can be used to establish the automatic online monitoring and fault diagnosis data base of a reciprocating pump.
2016, 35(2): 285-289.
doi: 10.13433/j.cnki.1003-8728.2016.0222
Abstract:
θFXZ measuring machine. Considering that there is not motion in y direction for this type measuring machine, the measurement principles of inner and outer diameters have been analyzed. Moreover, the relationship between the calibration error of rotary axis and the measurement errors of inner and outer diameters has been discussed. Then a fast calibration method of rotation axis has been proposed, and it is based on the measurement results of inner hole and outer circle in the standard ring. The experimental results indicate that measurement errors of the other standard rings are in the range of ±0.001 mm after calibrating the rotary axis with the present technique. This aforementioned calibration technique is able to achieve the calibration accuracy of the rotary axis. Besides, it is easy to implement the software, and the computer software can be developed to fulfill automatic calibration of the rotary axis.
θFXZ measuring machine. Considering that there is not motion in y direction for this type measuring machine, the measurement principles of inner and outer diameters have been analyzed. Moreover, the relationship between the calibration error of rotary axis and the measurement errors of inner and outer diameters has been discussed. Then a fast calibration method of rotation axis has been proposed, and it is based on the measurement results of inner hole and outer circle in the standard ring. The experimental results indicate that measurement errors of the other standard rings are in the range of ±0.001 mm after calibrating the rotary axis with the present technique. This aforementioned calibration technique is able to achieve the calibration accuracy of the rotary axis. Besides, it is easy to implement the software, and the computer software can be developed to fulfill automatic calibration of the rotary axis.
2016, 35(2): 290-295.
doi: 10.13433/j.cnki.1003-8728.2016.0223
Abstract:
The electro-hydrostatic actuator (EHA) using fixed displacement pump cannot avoid the problem that the motor's temperature rises fast when EHA under large load. In this article, a high-efficiency motor-pump is proposed, which uses a self-adapt variable pump. Self-adapt variable pump reduces the output torque of the motor based on the principle of lever. Then the motor's energy loss caused by the current is lowed and motor's heat becomes less. This article also analyzes the characteristic of self-adapt variable pump, brushless DC motor and high-efficiency motor-pump. Then the normalized plots of the EHA's output power and motor's loss power are gotten, which give a way to improve EHA's performance and reduce the heat under large load.
The electro-hydrostatic actuator (EHA) using fixed displacement pump cannot avoid the problem that the motor's temperature rises fast when EHA under large load. In this article, a high-efficiency motor-pump is proposed, which uses a self-adapt variable pump. Self-adapt variable pump reduces the output torque of the motor based on the principle of lever. Then the motor's energy loss caused by the current is lowed and motor's heat becomes less. This article also analyzes the characteristic of self-adapt variable pump, brushless DC motor and high-efficiency motor-pump. Then the normalized plots of the EHA's output power and motor's loss power are gotten, which give a way to improve EHA's performance and reduce the heat under large load.
2016, 35(2): 296-302.
doi: 10.13433/j.cnki.1003-8728.2016.0224
Abstract:
To design muffler efficiently with high capability of noise reduction is always a tough problem in control of vehicle exhaust noise. Considering that there are many parameters in the muffler design optimization, the design parameters of mufflers were analyzed by Latin Hypercube of design of experiment (DOE) based on the numerical modeling of transmission loss. Combining the multi-island genetic algorithm (MIGA) with genetic algorithm (GA), the optimization model of mufflers was established in which the transmission losses at the single peak frequency of exhaust noise and multiple peak frequencies are set as as the optimization objective, respectively. The result shows that the DOE method can effectively identify the parameters which affect muffler performance and simplify the optimization model of muffler. The optimization results of MIGA in both the single peak frequency and multiple peak frequency is better than that of GA, and the results of multiple peak frequency, optimization which is better than that of single peak frequency optimization, can reduce the exhaust noise by 20.98 dB. This study provides a new optimization design method of muffler.
To design muffler efficiently with high capability of noise reduction is always a tough problem in control of vehicle exhaust noise. Considering that there are many parameters in the muffler design optimization, the design parameters of mufflers were analyzed by Latin Hypercube of design of experiment (DOE) based on the numerical modeling of transmission loss. Combining the multi-island genetic algorithm (MIGA) with genetic algorithm (GA), the optimization model of mufflers was established in which the transmission losses at the single peak frequency of exhaust noise and multiple peak frequencies are set as as the optimization objective, respectively. The result shows that the DOE method can effectively identify the parameters which affect muffler performance and simplify the optimization model of muffler. The optimization results of MIGA in both the single peak frequency and multiple peak frequency is better than that of GA, and the results of multiple peak frequency, optimization which is better than that of single peak frequency optimization, can reduce the exhaust noise by 20.98 dB. This study provides a new optimization design method of muffler.
2016, 35(2): 303-308.
doi: 10.13433/j.cnki.1003-8728.2016.0225
Abstract:
In order to improve the explosion prevention and bullet-proof ability of wheel vehicle tires in the serious environment, a spring tire was put forward based on the performance of high strength and deformation recover of metal coil spring. Structure parameters of each tire part were analyzed and three-dimension model for spring tire was established. The performance of strength and stiffness of spring tire were analyzed with finite elements software and simple wheel vehicle experiment was operated. Combining the analysis, it is validated that the structure efficiently improves safety protection ability and theoretical model and simulation model of spring tire are right. With getting performance criterion of spring tire strength and stiffness, deformation phenomenon of experiment provides theoretical guidance for analysis and optimization of spring tire performance.
In order to improve the explosion prevention and bullet-proof ability of wheel vehicle tires in the serious environment, a spring tire was put forward based on the performance of high strength and deformation recover of metal coil spring. Structure parameters of each tire part were analyzed and three-dimension model for spring tire was established. The performance of strength and stiffness of spring tire were analyzed with finite elements software and simple wheel vehicle experiment was operated. Combining the analysis, it is validated that the structure efficiently improves safety protection ability and theoretical model and simulation model of spring tire are right. With getting performance criterion of spring tire strength and stiffness, deformation phenomenon of experiment provides theoretical guidance for analysis and optimization of spring tire performance.
2016, 35(2): 309-314.
doi: 10.13433/j.cnki.1003-8728.2016.0226
Abstract:
The working roads of the special engineering dump truck are rough and its working environments are extremely terrible. The excited vibration of the rough road reduces the ride comfort and the truck frame lifetime. To verify the dynamic responses of the frame, the typical road experiments of the special engineering dump truck are made on the building site. Because the nonlinear and non-stationary signal is difficult to be analyzed directly, the wavelet transforms are necessary in the process of the signal analysis. Combined the mode analysis with the wavelet transforms, the dynamic responses are seized in the signal of the key points of the frame. The weak points and potential problems are found.
The working roads of the special engineering dump truck are rough and its working environments are extremely terrible. The excited vibration of the rough road reduces the ride comfort and the truck frame lifetime. To verify the dynamic responses of the frame, the typical road experiments of the special engineering dump truck are made on the building site. Because the nonlinear and non-stationary signal is difficult to be analyzed directly, the wavelet transforms are necessary in the process of the signal analysis. Combined the mode analysis with the wavelet transforms, the dynamic responses are seized in the signal of the key points of the frame. The weak points and potential problems are found.
2016, 35(2): 315-319.
doi: 10.13433/j.cnki.1003-8728.2016.0227
Abstract:
In order to effectively predict the dynamics response of the track system of a track vehicle, the contacts between track, ground and wheel were described by using the nonlinear finite element method. The mathematical model was established and the contact boundary values were solved using the finite element method and the incremental equation. When the section shape of ground is semicircular and isosceles trapezoid and the soil type is dry sand, clay and silt loam, the wheel's location and track stiffness are different. Some examples were analyzed. It is concluded that the ground contact pressure at two corners is maximum when the track vehicle is on isosceles trapezoid and semicircular road; when the ground is soft, the ground pressure of the track is smaller and more uniform; when the distance between wheels and its sinkage is smaller, the maximum ground contact pressure of the track is greater; when the track stiffness is larger, track tension and the reaction force on the wheel increase gradually. The model thus established can reasonably predict the variation of tension force, geometric deformation and ground contact pressure of the track.
In order to effectively predict the dynamics response of the track system of a track vehicle, the contacts between track, ground and wheel were described by using the nonlinear finite element method. The mathematical model was established and the contact boundary values were solved using the finite element method and the incremental equation. When the section shape of ground is semicircular and isosceles trapezoid and the soil type is dry sand, clay and silt loam, the wheel's location and track stiffness are different. Some examples were analyzed. It is concluded that the ground contact pressure at two corners is maximum when the track vehicle is on isosceles trapezoid and semicircular road; when the ground is soft, the ground pressure of the track is smaller and more uniform; when the distance between wheels and its sinkage is smaller, the maximum ground contact pressure of the track is greater; when the track stiffness is larger, track tension and the reaction force on the wheel increase gradually. The model thus established can reasonably predict the variation of tension force, geometric deformation and ground contact pressure of the track.
2016, 35(2): 320-324.
doi: 10.13433/j.cnki.1003-8728.2016.0228
Abstract:
Vibration properties of many assembled mechanical systems depend on frictional damping in bolted joints. In this paper,the bolt joint interfaces of power-train are studied, and the nonstandard test device is designed. The testing process and parameter identification methods of shear stiffness, normal stiffness and damping are confirmed through many-times experiments. The influence law of dynamic characteristic of joint interface by contact press, material and contact states is obtained. Based on the test data, the thin film element equivalent mechanical model is proposed and the gear-box shell equivalent calculation model which takes into account the interface effect is constructed. The modal analysis results indicate that the equivalent models have high precision and better engineering applicability.
Vibration properties of many assembled mechanical systems depend on frictional damping in bolted joints. In this paper,the bolt joint interfaces of power-train are studied, and the nonstandard test device is designed. The testing process and parameter identification methods of shear stiffness, normal stiffness and damping are confirmed through many-times experiments. The influence law of dynamic characteristic of joint interface by contact press, material and contact states is obtained. Based on the test data, the thin film element equivalent mechanical model is proposed and the gear-box shell equivalent calculation model which takes into account the interface effect is constructed. The modal analysis results indicate that the equivalent models have high precision and better engineering applicability.
2016, 35(2): 325-328.
doi: 10.13433/j.cnki.1003-8728.2016.0229
Abstract:
Generally, is difficult to machine with high hardness and brittleness. Electrical discharge machining is an effective method for NdFeB. In order to achieve high efficient and high quality, the technological rules in the EDM process of NdFeB is necessary. In this paper, the experiment planning is to combine the single factor experiment and the orthogonal experiment. The EDM process model is established by using SPSS software under a large number of experiments. the rationality of the regression model by compariing the regression results with the actual processing results is validated. By designing a new experiment, the technological effects of EDM is predicted via MATLAB software and the predicted values are close to the actual values under different process parameters.
Generally, is difficult to machine with high hardness and brittleness. Electrical discharge machining is an effective method for NdFeB. In order to achieve high efficient and high quality, the technological rules in the EDM process of NdFeB is necessary. In this paper, the experiment planning is to combine the single factor experiment and the orthogonal experiment. The EDM process model is established by using SPSS software under a large number of experiments. the rationality of the regression model by compariing the regression results with the actual processing results is validated. By designing a new experiment, the technological effects of EDM is predicted via MATLAB software and the predicted values are close to the actual values under different process parameters.
