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RSS2017 Vol. 36, No. 6
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2017, 36(6): 821-826.
doi: 10.13433/j.cnki.1003-8728.2017.0601
PDF 994KB
Abstract:
The mathematical model of real time motion state of the driven sprocket is established as there is lacking of an effective mathematical model to describe the effect of the polygon effect on the chain drive. The real time motion state of the driven sprocket is calculated by using the 4 step R-K method to solve the differential equation. As the angular acceleration curve shows, besides the dynamic load caused by the meshing of sprocket and pitch, there is an inherent dynamic load in the chain drive. The chain drive is a creeping forward process after analyzing the attitude of the chain. Besides, the effects of transmission ratio and initial angle of the sprocket on the drive process are also analyzed in this paper. At last, the mathematical model is proved to be valid to reflect the chain transmission after comparing the theoretical value and simulation value acquired by using Adams.
The mathematical model of real time motion state of the driven sprocket is established as there is lacking of an effective mathematical model to describe the effect of the polygon effect on the chain drive. The real time motion state of the driven sprocket is calculated by using the 4 step R-K method to solve the differential equation. As the angular acceleration curve shows, besides the dynamic load caused by the meshing of sprocket and pitch, there is an inherent dynamic load in the chain drive. The chain drive is a creeping forward process after analyzing the attitude of the chain. Besides, the effects of transmission ratio and initial angle of the sprocket on the drive process are also analyzed in this paper. At last, the mathematical model is proved to be valid to reflect the chain transmission after comparing the theoretical value and simulation value acquired by using Adams.
2017, 36(6): 827-833.
doi: 10.13433/j.cnki.1003-8728.2017.0602
Abstract:
In order to discover decision rules from incomplete fault diagnosis information containing multiple unknown attribute values, a knowledge discovery method of incomplete fault diagnosis information by using valued characteristic relation is proposed. Firstly, the unknown attribute value types are determined according to the reasons for incomplete information. Secondly, the incomplete fault diagnosis information is analyzed by using the valued characteristic relation. Finally, the decision rules for fault diagnosis are discovered according to the attribute reduction algorithm based on the valued characteristic relation. The effectiveness of the method is demonstrated with the diagnosis case of faulty gearbox. The experimental results show that the present method can directly discover the accurate decision rules from incomplete fault diagnosis information with three categories of unknown attribute values.
In order to discover decision rules from incomplete fault diagnosis information containing multiple unknown attribute values, a knowledge discovery method of incomplete fault diagnosis information by using valued characteristic relation is proposed. Firstly, the unknown attribute value types are determined according to the reasons for incomplete information. Secondly, the incomplete fault diagnosis information is analyzed by using the valued characteristic relation. Finally, the decision rules for fault diagnosis are discovered according to the attribute reduction algorithm based on the valued characteristic relation. The effectiveness of the method is demonstrated with the diagnosis case of faulty gearbox. The experimental results show that the present method can directly discover the accurate decision rules from incomplete fault diagnosis information with three categories of unknown attribute values.
2017, 36(6): 834-840.
doi: 10.13433/j.cnki.1003-8728.2017.0603
Abstract:
Considering the effect of the gaps, the internal field model of variable displacement vane oil pump was established. Based on RNG k-ε turbulent fluid model, numerical simulation of turbulent flow on variable displacement vane oil pump under steady working condition was implemented by using a computational fluid dynamics code, the flow and pressure were obtained, and the cavitation phenomenon was predicted. The accuracy of the simulation model was verified by comparing the simulation and experimental results. Considering the effect of unloading groove, the pressure pulsation in time domain and frequency domain at the monitoring points in internal field were simulated, which showed that the pressure pulsation of the trapped oil area was the biggest and the dominant frequency was the fundamental frequency. The noise test of the oil pump indicated that the dominant frequency of noise was coincided with the fundamental frequency of pressure pulsation. The results show that the noise of variable displacement vane oil pump is mainly caused by the pressure pulsation, and pressure pulsation of the trapped oil area can be reduced effectively by unloading groove.
Considering the effect of the gaps, the internal field model of variable displacement vane oil pump was established. Based on RNG k-ε turbulent fluid model, numerical simulation of turbulent flow on variable displacement vane oil pump under steady working condition was implemented by using a computational fluid dynamics code, the flow and pressure were obtained, and the cavitation phenomenon was predicted. The accuracy of the simulation model was verified by comparing the simulation and experimental results. Considering the effect of unloading groove, the pressure pulsation in time domain and frequency domain at the monitoring points in internal field were simulated, which showed that the pressure pulsation of the trapped oil area was the biggest and the dominant frequency was the fundamental frequency. The noise test of the oil pump indicated that the dominant frequency of noise was coincided with the fundamental frequency of pressure pulsation. The results show that the noise of variable displacement vane oil pump is mainly caused by the pressure pulsation, and pressure pulsation of the trapped oil area can be reduced effectively by unloading groove.
2017, 36(6): 841-847.
doi: 10.13433/j.cnki.1003-8728.2017.0604
Abstract:
The impact of valve-train could have a great effect on the stress distribution of cylinder head. Firstly, In order to get the cycle impact load of the cylinder head valve seat resulting from the valve-train, the multi-body dynamics simulation model for a diesel engine valve train was established. After that, it is necessary to analyze the alteration of the stress distribution of cylinder head due to the impact load of valve-train. Based on this results, considering the influence of thermal stresses and cyclic mechanical stress and impact pressure, the combination structure model which containing the cylinder head, the body, cooling water jacket and other related component was established to simulate the transient dynamic response. Finally, it is also required to compare the difference between the two multi-body dynamics simulation models. The results show that the stress distribution of cylinder head which considering the variable impact pressure of the valve-train display a more reliable conclusion. Besides, the stress of cylinder head intake and exhaust valve seat were at significantly augmented and its value can increase by 10%. In addition, stress at the fire deck surface also got augmented and its value can increase to 30 MPa. Meanwhile, the overall stress field of the cylinder head has been varying degrees of increase.
The impact of valve-train could have a great effect on the stress distribution of cylinder head. Firstly, In order to get the cycle impact load of the cylinder head valve seat resulting from the valve-train, the multi-body dynamics simulation model for a diesel engine valve train was established. After that, it is necessary to analyze the alteration of the stress distribution of cylinder head due to the impact load of valve-train. Based on this results, considering the influence of thermal stresses and cyclic mechanical stress and impact pressure, the combination structure model which containing the cylinder head, the body, cooling water jacket and other related component was established to simulate the transient dynamic response. Finally, it is also required to compare the difference between the two multi-body dynamics simulation models. The results show that the stress distribution of cylinder head which considering the variable impact pressure of the valve-train display a more reliable conclusion. Besides, the stress of cylinder head intake and exhaust valve seat were at significantly augmented and its value can increase by 10%. In addition, stress at the fire deck surface also got augmented and its value can increase to 30 MPa. Meanwhile, the overall stress field of the cylinder head has been varying degrees of increase.
2017, 36(6): 848-854.
doi: 10.13433/j.cnki.1003-8728.2017.0605
Abstract:
Because the return ability of the electric power steering (EPS) system of a steering wheel is excessive at its high speed but insufficient at its low speed, a new return-to-center control strategy for controlling its speed was put forward. Firstly, the dynamics model of the R-EPS system was built. Then the method for obtaining return curves was introduced. Finally, the control strategy was simulated with Adams/Simulink. Compared with the fuzzy PID control strategy based on the conventional angle of the steering wheel, our control strategy based on the angular velocity of the steering wheel is innovative. The simulation results show that our control strategy gains a better return ability than the conventional control strategy and that the return is faster and more accurate.
Because the return ability of the electric power steering (EPS) system of a steering wheel is excessive at its high speed but insufficient at its low speed, a new return-to-center control strategy for controlling its speed was put forward. Firstly, the dynamics model of the R-EPS system was built. Then the method for obtaining return curves was introduced. Finally, the control strategy was simulated with Adams/Simulink. Compared with the fuzzy PID control strategy based on the conventional angle of the steering wheel, our control strategy based on the angular velocity of the steering wheel is innovative. The simulation results show that our control strategy gains a better return ability than the conventional control strategy and that the return is faster and more accurate.
2017, 36(6): 855-862.
doi: 10.13433/j.cnki.1003-8728.2017.0606
Abstract:
In designing robust products that have aleatory uncertainty and epistemic uncertainty, the existing theories of probability, fuzzy set, interval and so on are not enough to establish new and robust evaluation indexes. To solve this problem, various types of uncertainty were described and processed according to the evidence theory. Then the evidence model for product quality evaluation indexes was established; the uncertainty quantification and propagation methods were developed. Under the aleatory and epistemic uncertainties, we proposed the robust indexes and methods for evaluating product quality. The simulation results show the effectiveness of the proposed indexes and methods.
In designing robust products that have aleatory uncertainty and epistemic uncertainty, the existing theories of probability, fuzzy set, interval and so on are not enough to establish new and robust evaluation indexes. To solve this problem, various types of uncertainty were described and processed according to the evidence theory. Then the evidence model for product quality evaluation indexes was established; the uncertainty quantification and propagation methods were developed. Under the aleatory and epistemic uncertainties, we proposed the robust indexes and methods for evaluating product quality. The simulation results show the effectiveness of the proposed indexes and methods.
2017, 36(6): 863-868.
doi: 10.13433/j.cnki.1003-8728.2017.0607
Abstract:
For planar path mechanism, a novel reliability design method is proposed with dimension tolerance and joint clearance. Considering the mechanism with joint clearance, a hybrid dimension reduction method (HDRM) is adopted to handle the joint clearance variables in kinematic error function. A probabilistic model of per output component error is then established. The joint probability density function of the output components is used to estimate the composite mechanism kinematic reliability. A reliability design model of the planar path mechanisms is established which objective is to minimize the structure error and the kinematic composite reliability is introduced to the constraints. A numerical example is given to illustrate the effectiveness of the proposed method.
For planar path mechanism, a novel reliability design method is proposed with dimension tolerance and joint clearance. Considering the mechanism with joint clearance, a hybrid dimension reduction method (HDRM) is adopted to handle the joint clearance variables in kinematic error function. A probabilistic model of per output component error is then established. The joint probability density function of the output components is used to estimate the composite mechanism kinematic reliability. A reliability design model of the planar path mechanisms is established which objective is to minimize the structure error and the kinematic composite reliability is introduced to the constraints. A numerical example is given to illustrate the effectiveness of the proposed method.
2017, 36(6): 869-876.
doi: 10.13433/j.cnki.1003-8728.2017.0608
Abstract:
Considering the feature that the wear experiment cost for the circuit breaker mechanism system is very high, the wear prediction model is established for the dangerous joint. Based on the pin-on-disc experiments data, two kinds of typical models are established for the wear prediction. The comparative study shows that the model based on the Elman neural network can accurately reflect the inherent wear law between wear rate and contact pressure, sliding velocity and material hardness with a high prediction precision. Considering the clearance in revolute joint, the kinematic parameters are obtained by using ADAMS software based on the elastic-damping contact force model. Then, the trained Elman model is employed to predict the wear of dangerous joint, using the parameters transformed by Hertz contact model. It can be seen from iterative analysis that wear occurs seriously in some special areas on bushing surface. The comparison result indicates that the wear calculation from prediction model is more useful for wear failure criteria than the Archard model which uses constant coefficient.
Considering the feature that the wear experiment cost for the circuit breaker mechanism system is very high, the wear prediction model is established for the dangerous joint. Based on the pin-on-disc experiments data, two kinds of typical models are established for the wear prediction. The comparative study shows that the model based on the Elman neural network can accurately reflect the inherent wear law between wear rate and contact pressure, sliding velocity and material hardness with a high prediction precision. Considering the clearance in revolute joint, the kinematic parameters are obtained by using ADAMS software based on the elastic-damping contact force model. Then, the trained Elman model is employed to predict the wear of dangerous joint, using the parameters transformed by Hertz contact model. It can be seen from iterative analysis that wear occurs seriously in some special areas on bushing surface. The comparison result indicates that the wear calculation from prediction model is more useful for wear failure criteria than the Archard model which uses constant coefficient.
2017, 36(6): 877-882.
doi: 10.13433/j.cnki.1003-8728.2017.0609
Abstract:
Based on a torsional-transverse coupling model of a 2K-H spur planetary gear, the equation formula of vibration energy of planetary gear transmission system was derived. The relationship between the parameter sensitivity of the planetary gear and vibration energy was analyzed. Potential energy and kinetic energy of the planetary gear that contains four planet gears were calculated under the operation conditions, in which the ring gear is fixed. The analysis results showed that the vibration energy of the planetary gear is mainly dominated by strain energy. It may safely draw the conclusion that the influence law of the planetary gear parameters on eigenvalues can be obtained from the variety of vibration energy of each component with the different order of vibration.
Based on a torsional-transverse coupling model of a 2K-H spur planetary gear, the equation formula of vibration energy of planetary gear transmission system was derived. The relationship between the parameter sensitivity of the planetary gear and vibration energy was analyzed. Potential energy and kinetic energy of the planetary gear that contains four planet gears were calculated under the operation conditions, in which the ring gear is fixed. The analysis results showed that the vibration energy of the planetary gear is mainly dominated by strain energy. It may safely draw the conclusion that the influence law of the planetary gear parameters on eigenvalues can be obtained from the variety of vibration energy of each component with the different order of vibration.
2017, 36(6): 883-889.
doi: 10.13433/j.cnki.1003-8728.2017.0610
Abstract:
Based on the analysis of structure and work principle of the Mecanum wheel, the kinematics model of the omni-directional movement platform with four wheels is established by the vector analysis method. As the conventional PID is not an adaptive control system and its real-time response speed needs to be improved, an embedded self-adaptive controller of the omni-directional movement platform is designed in this study based on the CMAC+PID combined control algorithm. The MATLAB simulation and the experimental analysis of DC motor speed regulation are carried out, and the whole motion performance of the prototype is tested by several typical experiments. The results show that the kinematics model of the omni-directional movement platform with Mecanum wheel is reasonable, the CMAC+PID self-adaptive controller has the advantages of fast dynamic response speed, high control precision and good robustness. The prototype can implement lateral movement, vertical movement, rotation on the spot and arbitrary directional movement in the plane, and its overall performance can meet the engineering application requirement.
Based on the analysis of structure and work principle of the Mecanum wheel, the kinematics model of the omni-directional movement platform with four wheels is established by the vector analysis method. As the conventional PID is not an adaptive control system and its real-time response speed needs to be improved, an embedded self-adaptive controller of the omni-directional movement platform is designed in this study based on the CMAC+PID combined control algorithm. The MATLAB simulation and the experimental analysis of DC motor speed regulation are carried out, and the whole motion performance of the prototype is tested by several typical experiments. The results show that the kinematics model of the omni-directional movement platform with Mecanum wheel is reasonable, the CMAC+PID self-adaptive controller has the advantages of fast dynamic response speed, high control precision and good robustness. The prototype can implement lateral movement, vertical movement, rotation on the spot and arbitrary directional movement in the plane, and its overall performance can meet the engineering application requirement.
2017, 36(6): 890-894.
doi: 10.13433/j.cnki.1003-8728.2017.0611
Abstract:
The contact modes of closed switch are firstly analyzed to get the natural frequency and modes. The different positive and negative dual wave loads are designed to ensure the two variables of maximum pseudo velocity, acceleration and displacement be equal by using the finite element software to simulate the shock impact of the reed contact switch. The contact pressure and the root stress of the reed switch vibrate periodicity closed to the first-order natural frequency when the shocking stopped; the maximum acceleration response just affects the contact pressure but has no effects on root stress; the pseudo velocity response just affects the root stress but has no effects on contact pressure; the maximum displacement response has no effects on contact pressure or root stress.
The contact modes of closed switch are firstly analyzed to get the natural frequency and modes. The different positive and negative dual wave loads are designed to ensure the two variables of maximum pseudo velocity, acceleration and displacement be equal by using the finite element software to simulate the shock impact of the reed contact switch. The contact pressure and the root stress of the reed switch vibrate periodicity closed to the first-order natural frequency when the shocking stopped; the maximum acceleration response just affects the contact pressure but has no effects on root stress; the pseudo velocity response just affects the root stress but has no effects on contact pressure; the maximum displacement response has no effects on contact pressure or root stress.
2017, 36(6): 895-902.
doi: 10.13433/j.cnki.1003-8728.2017.0612
Abstract:
In this paper, a systematically parametric design method based on the digital design method and by using computer programming languages:C#.NET、ANSYS Parametric Design Language and programming is presented, which includes 3D model design and its non-geometric information parameterization and APDL parametric analysis method based on table view and structural optimization design method based on the parametric model via finite element method. The method is applied for the parametric design and analysis of a fixed single tripper of the bucket wheel stacker-reclaimer. The example shows that this advanced digital design method greatly improved the design efficiency of non-standard products, increasing the reusability of the model and reducing the design error, address the key issues in the digital development.
In this paper, a systematically parametric design method based on the digital design method and by using computer programming languages:C#.NET、ANSYS Parametric Design Language and programming is presented, which includes 3D model design and its non-geometric information parameterization and APDL parametric analysis method based on table view and structural optimization design method based on the parametric model via finite element method. The method is applied for the parametric design and analysis of a fixed single tripper of the bucket wheel stacker-reclaimer. The example shows that this advanced digital design method greatly improved the design efficiency of non-standard products, increasing the reusability of the model and reducing the design error, address the key issues in the digital development.
2017, 36(6): 903-908.
doi: 10.13433/j.cnki.1003-8728.2017.0613
Abstract:
Based on comprehensive weight and quality loss, we present a method for robust design that has multiple quality characteristics to solve the weight and optimization problems. Firstly, we employ the quality loss to measure the robustness of multiple quality characteristics. Secondly, the subjective weight is calculated according to the data which passed the Kendall's concordance coefficient test. Meanwhile, the concept of entropy weight is introduced to calculate the objective weight by considering the information on responses. Then the comprehensive weights can be determined by the above two kinds of weight. Thirdly, the validity of the method and the significance of the coefficient are taken into consideration when conducting the regression analysis. Finally, a case study is given to illustrate that the improved method can find the optimal solution in the global range.
Based on comprehensive weight and quality loss, we present a method for robust design that has multiple quality characteristics to solve the weight and optimization problems. Firstly, we employ the quality loss to measure the robustness of multiple quality characteristics. Secondly, the subjective weight is calculated according to the data which passed the Kendall's concordance coefficient test. Meanwhile, the concept of entropy weight is introduced to calculate the objective weight by considering the information on responses. Then the comprehensive weights can be determined by the above two kinds of weight. Thirdly, the validity of the method and the significance of the coefficient are taken into consideration when conducting the regression analysis. Finally, a case study is given to illustrate that the improved method can find the optimal solution in the global range.
2017, 36(6): 909-914.
doi: 10.13433/j.cnki.1003-8728.2017.0614
Abstract:
Non-contact electromagnetic loading has achieved the dynamic loading of high speed motorized spindle. In the process of dynamic loading, due to the high speed rotation of the solid loading plate (iron-nickel alloy), eddy currents and skin effect appearing in the plate exercise their impact on the magnetic field produced by the electromagnet, and as the speed increases, the impact is more obvious, causing the radial force to decrease gradually and the tangential force to appear. This article aims to study the relationship among tangential forces under different conditions and uses the analytical method and the finite element method to calculate the tangential force during loading until the calculation results are in good agreement. By analyzing the dynamic process of loading, the article discovers that, in the process of electromagnetic loading, the tangential force changes with certain regularity, namely the tangential force increases or decreases with the differences in the speed, current and air gap of the high speed motorized spindle. The loading law of tangential force thus obtained provides the basis for improving the electromagnetic loading device.
Non-contact electromagnetic loading has achieved the dynamic loading of high speed motorized spindle. In the process of dynamic loading, due to the high speed rotation of the solid loading plate (iron-nickel alloy), eddy currents and skin effect appearing in the plate exercise their impact on the magnetic field produced by the electromagnet, and as the speed increases, the impact is more obvious, causing the radial force to decrease gradually and the tangential force to appear. This article aims to study the relationship among tangential forces under different conditions and uses the analytical method and the finite element method to calculate the tangential force during loading until the calculation results are in good agreement. By analyzing the dynamic process of loading, the article discovers that, in the process of electromagnetic loading, the tangential force changes with certain regularity, namely the tangential force increases or decreases with the differences in the speed, current and air gap of the high speed motorized spindle. The loading law of tangential force thus obtained provides the basis for improving the electromagnetic loading device.
2017, 36(6): 915-918.
doi: 10.13433/j.cnki.1003-8728.2017.0615
Abstract:
To achieve the fault detection and failure analysis of rolling bearing for small samples, a rolling bearing fault diagnosis method is proposed based on the local mean decomposition (LMD) energy entropy and the support vector machines (SVM). In this method, the rolling bearing vibration signals are decomposed into several production functions (PF) by using the LMD signal processing method. Then the energy entropy of the PF components for fault feature extraction is calculated and the features are input into the SVM classifiers for training and testing. Finally, the fault diagnosis of rolling bearing is performed. The experimental results show that the proposed method can be used effectively to identify and classify the type of rolling bearing fault accuratelyfor small samples.
To achieve the fault detection and failure analysis of rolling bearing for small samples, a rolling bearing fault diagnosis method is proposed based on the local mean decomposition (LMD) energy entropy and the support vector machines (SVM). In this method, the rolling bearing vibration signals are decomposed into several production functions (PF) by using the LMD signal processing method. Then the energy entropy of the PF components for fault feature extraction is calculated and the features are input into the SVM classifiers for training and testing. Finally, the fault diagnosis of rolling bearing is performed. The experimental results show that the proposed method can be used effectively to identify and classify the type of rolling bearing fault accuratelyfor small samples.
2017, 36(6): 919-924.
doi: 10.13433/j.cnki.1003-8728.2017.0616
Abstract:
The foot measurement of wearer and motion recognition are very important for the lower limb power-assisted exoskeleton to follow the motion of the wearer and provide power. A insole foot force measuring system was proposed for the control of exoskeleton robot. The measuring system and signal conditioning circuit were designed, and walking experiments for foot force measuring system were implemented. The foot force measuring system was applied to the control of lower limb power-assisted exoskeleton. The results showed that the foot force data which outputted by measuring system can realize the motion control of exoskeleton leg.
The foot measurement of wearer and motion recognition are very important for the lower limb power-assisted exoskeleton to follow the motion of the wearer and provide power. A insole foot force measuring system was proposed for the control of exoskeleton robot. The measuring system and signal conditioning circuit were designed, and walking experiments for foot force measuring system were implemented. The foot force measuring system was applied to the control of lower limb power-assisted exoskeleton. The results showed that the foot force data which outputted by measuring system can realize the motion control of exoskeleton leg.
2017, 36(6): 925-932.
doi: 10.13433/j.cnki.1003-8728.2017.0617
Abstract:
In order to find an effective method of fault classification of gear transmission system, fault tests are conducted on the planetary gear transmission system to acquire vibration signals. Empirical mode decomposition (EMD) method is used to process the vibration signals. The sum of several intrinsic mode function (IMF) components are obtained and the auto regressive (AR) model of the former four IMF components is established. and the regression parameter sequence is obtained, then the correlation dimension, maximum Lyapunov exponent and sample entropy are calculated, and these three chaotic characteristic parameters are used as fault identification features. The information of different chaotic characteristic parameters of different measuring points are fused and fed as input vector of support vector machine (SVM) to establish six kinds of different state of the training sets, then the classification of fault type can be achieved. The results indicate that the use the experimental vibration signals proceeded by EMD and AR modeling, the fault classification accuracy can be improve.
In order to find an effective method of fault classification of gear transmission system, fault tests are conducted on the planetary gear transmission system to acquire vibration signals. Empirical mode decomposition (EMD) method is used to process the vibration signals. The sum of several intrinsic mode function (IMF) components are obtained and the auto regressive (AR) model of the former four IMF components is established. and the regression parameter sequence is obtained, then the correlation dimension, maximum Lyapunov exponent and sample entropy are calculated, and these three chaotic characteristic parameters are used as fault identification features. The information of different chaotic characteristic parameters of different measuring points are fused and fed as input vector of support vector machine (SVM) to establish six kinds of different state of the training sets, then the classification of fault type can be achieved. The results indicate that the use the experimental vibration signals proceeded by EMD and AR modeling, the fault classification accuracy can be improve.
2017, 36(6): 933-937.
doi: 10.13433/j.cnki.1003-8728.2017.0618
Abstract:
To control the noise of internal combustion engine and predict engine combustion noise during the engine initial design stage, a new methodology was presented. According to the principle of noise superposition and in-cylinder pressure decomposition, the combustion noise and combustion pressure can be extracted from the total noise and in-cylinder pressure. A model of combustion noise transfer function was built in this paper and it was used to predict the combustion noise of a new developed gasoline engine. The predicted result was verified by the experiment. The experiment proved that the approach presented in this paper can be used to evaluate combustion noise of gasoline engine during the development phase and is important in the process of reducing combustion noise and increasing acoustic quality.
To control the noise of internal combustion engine and predict engine combustion noise during the engine initial design stage, a new methodology was presented. According to the principle of noise superposition and in-cylinder pressure decomposition, the combustion noise and combustion pressure can be extracted from the total noise and in-cylinder pressure. A model of combustion noise transfer function was built in this paper and it was used to predict the combustion noise of a new developed gasoline engine. The predicted result was verified by the experiment. The experiment proved that the approach presented in this paper can be used to evaluate combustion noise of gasoline engine during the development phase and is important in the process of reducing combustion noise and increasing acoustic quality.
2017, 36(6): 938-942.
doi: 10.13433/j.cnki.1003-8728.2017.0619
Abstract:
The cumulative damage of vehicle battery pack under repeated impact loads was analyzed. The finite element model of the pack was build with Hypermesh software, the dynamic responses of the pack structure under impact load were calculated by using LS-DYNA software. The distribution and the maximum von Mises stress and plastic strain of the pack structure under impact load were obtained. The restarting technique of LS-DYNA software was adopted to transmit the damage parameters, hence the cumulative analysis of stress and plastic strain of the structure under repeated impact load can be obtained. Finally, the distribution of damage of the pack structure can be achieved with Johnson-Cook failure model, which can serve as an important reference for the improving design of the structure.
The cumulative damage of vehicle battery pack under repeated impact loads was analyzed. The finite element model of the pack was build with Hypermesh software, the dynamic responses of the pack structure under impact load were calculated by using LS-DYNA software. The distribution and the maximum von Mises stress and plastic strain of the pack structure under impact load were obtained. The restarting technique of LS-DYNA software was adopted to transmit the damage parameters, hence the cumulative analysis of stress and plastic strain of the structure under repeated impact load can be obtained. Finally, the distribution of damage of the pack structure can be achieved with Johnson-Cook failure model, which can serve as an important reference for the improving design of the structure.
2017, 36(6): 943-949.
doi: 10.13433/j.cnki.1003-8728.2017.0620
Abstract:
In the case of the bumper impact, the maximum energy absorbed by the bumper crash can be reflected by the total pressure collapse. In this paper, a multi-objective optimization problem was formulated, which with maximizing the absorption energy of the bumper and the mass ratio, minimizing the maximum variable of the X direction and the initial velocity decay time as objectives. The thickness of bumper beam, the left strengthen plate, the right strengthen plate and the wall thickness of energy absorption block were as the design variables. The impact information of the bumper beam under different design variables can be obtained by using the finite element software LS-DYNA. The objective functions were constructed based on the response surface method. And the optimal variable values were found in each response surface respectively. The multi-objective optimization can be solved by using the ideal point method, meeting ultimately the design requirements of structure.
In the case of the bumper impact, the maximum energy absorbed by the bumper crash can be reflected by the total pressure collapse. In this paper, a multi-objective optimization problem was formulated, which with maximizing the absorption energy of the bumper and the mass ratio, minimizing the maximum variable of the X direction and the initial velocity decay time as objectives. The thickness of bumper beam, the left strengthen plate, the right strengthen plate and the wall thickness of energy absorption block were as the design variables. The impact information of the bumper beam under different design variables can be obtained by using the finite element software LS-DYNA. The objective functions were constructed based on the response surface method. And the optimal variable values were found in each response surface respectively. The multi-objective optimization can be solved by using the ideal point method, meeting ultimately the design requirements of structure.
2017, 36(6): 950-954.
doi: 10.13433/j.cnki.1003-8728.2017.0621
Abstract:
In order to improve the performance of heavy duty diesel engine and the turbo lag of exhaust-driven turbocharger, a turbo lag compensator (TLS) system is designed. The system is composed of a high speed electromagnetic valve, a high pressure air tank and a controller. The system is also validated using real road experiment test based on the assembly and installation of the TLS. It is found from the vehicle acceleration test that the time of reaching the maximum torque is decreased to 3 s compared with the original 8 s, which means the vehicle acceleration performance can be improved with the TLS system. And the fuel economy tests show that the fuel consumption per 100 km can be reduced 3.4% with the TLS system measured at a specific vehicle simulation operating mode, which indicates that the vehicle fuel economy can be improved with the proposed TLS system.
In order to improve the performance of heavy duty diesel engine and the turbo lag of exhaust-driven turbocharger, a turbo lag compensator (TLS) system is designed. The system is composed of a high speed electromagnetic valve, a high pressure air tank and a controller. The system is also validated using real road experiment test based on the assembly and installation of the TLS. It is found from the vehicle acceleration test that the time of reaching the maximum torque is decreased to 3 s compared with the original 8 s, which means the vehicle acceleration performance can be improved with the TLS system. And the fuel economy tests show that the fuel consumption per 100 km can be reduced 3.4% with the TLS system measured at a specific vehicle simulation operating mode, which indicates that the vehicle fuel economy can be improved with the proposed TLS system.
2017, 36(6): 955-959.
doi: 10.13433/j.cnki.1003-8728.2017.0622
Abstract:
In stamping, the unique fracture phenomenon of advanced high-strength steel appears due to the competition of shear and necking, which affects the forming process of car plate design, prevents the dimensional accuracy and further improvement of forming quality of dual phase steel parts. The modified Mohr coulomb criterion can predict the ductile fracture of dual phase steel, but it is not easy to determine its parameters. A ductile fracture criterion is put forward which is both easy to use in engineering and unify the phenomenon of tensile and shear, and the vectorized user material subroutine (VUMAT) of ABAQUS is written based on Hill'48 anisotropic yield criterion, and the experiment of DP780 stretch bending forming is simulated by comparing the two ductile fracture criterions, finding that new standards can be used for predicting the stamping fracture of dual phase steel, and the errors meet engineering requirements.
In stamping, the unique fracture phenomenon of advanced high-strength steel appears due to the competition of shear and necking, which affects the forming process of car plate design, prevents the dimensional accuracy and further improvement of forming quality of dual phase steel parts. The modified Mohr coulomb criterion can predict the ductile fracture of dual phase steel, but it is not easy to determine its parameters. A ductile fracture criterion is put forward which is both easy to use in engineering and unify the phenomenon of tensile and shear, and the vectorized user material subroutine (VUMAT) of ABAQUS is written based on Hill'48 anisotropic yield criterion, and the experiment of DP780 stretch bending forming is simulated by comparing the two ductile fracture criterions, finding that new standards can be used for predicting the stamping fracture of dual phase steel, and the errors meet engineering requirements.
2017, 36(6): 960-964.
doi: 10.13433/j.cnki.1003-8728.2017.0623
Abstract:
The most commonly used material for fused deposition molding FDM build parts is polylactic acid PLA. CHCL3 is used for spray polishing surface which can improve surface quality of FDM build parts. This paper investigates the effect of the polishing temperature, polishing time and polishing concentration on the FDM build parts. Experimental results show that the surface roughness of FDM build parts reduces with the increasing of temperature and time, but the surface roughness of FDM build parts increase slightly after the temperature and time reaching a certain value. With the increasing of concentration of polishing liquid, the surface roughness of FDM build parts reduces sharply. At a polishing temperature of 60℃, polishing time of 7 min and a concentration of polishing liquid of 100%, the surface roughness of FDM build parts after polishing decreases sharply; the surface topography has significantly improved; and the effect on the dimensional accuracy and quality of parts is small.
The most commonly used material for fused deposition molding FDM build parts is polylactic acid PLA. CHCL3 is used for spray polishing surface which can improve surface quality of FDM build parts. This paper investigates the effect of the polishing temperature, polishing time and polishing concentration on the FDM build parts. Experimental results show that the surface roughness of FDM build parts reduces with the increasing of temperature and time, but the surface roughness of FDM build parts increase slightly after the temperature and time reaching a certain value. With the increasing of concentration of polishing liquid, the surface roughness of FDM build parts reduces sharply. At a polishing temperature of 60℃, polishing time of 7 min and a concentration of polishing liquid of 100%, the surface roughness of FDM build parts after polishing decreases sharply; the surface topography has significantly improved; and the effect on the dimensional accuracy and quality of parts is small.
2017, 36(6): 965-970.
doi: 10.13433/j.cnki.1003-8728.2017.0624
Abstract:
In three-dimensional printing process,the behavior and the properties of the droplet has an great impact on the quality of the printed parts when the binder penetrate into the materials. This paper established a numerical model to study the impact process of a single droplet on the porous media, including the expansion, penetration. In order to accurately describe the dynamic effect of the droplet flow, VOF (Volume of fluid) model is used to track the droplet shape. The PISO (Pressure implicit split operator) algorithm is selected to solve the pressure-velocity combinations. the effect of the droplet characteristics, the impact velocity of the droplet and porosity of the porous media on droplet expansion characteristics was focused. The results showed that the droplet extension radius increases with the increasing of initial droplet velocity and decrease with the increasing of viscosity; the smaller the porosity of the porous media is and the bigger the expansion radius of the droplet, the smaller the penetration thickness.
In three-dimensional printing process,the behavior and the properties of the droplet has an great impact on the quality of the printed parts when the binder penetrate into the materials. This paper established a numerical model to study the impact process of a single droplet on the porous media, including the expansion, penetration. In order to accurately describe the dynamic effect of the droplet flow, VOF (Volume of fluid) model is used to track the droplet shape. The PISO (Pressure implicit split operator) algorithm is selected to solve the pressure-velocity combinations. the effect of the droplet characteristics, the impact velocity of the droplet and porosity of the porous media on droplet expansion characteristics was focused. The results showed that the droplet extension radius increases with the increasing of initial droplet velocity and decrease with the increasing of viscosity; the smaller the porosity of the porous media is and the bigger the expansion radius of the droplet, the smaller the penetration thickness.
2017, 36(6): 971-977.
doi: 10.13433/j.cnki.1003-8728.2017.0625
Abstract:
In this paper, the structural damping material optimal layout is studied. Based on the principle of virtual work, the vibration differential equation of damping plate is built. According to related basic hypothesis of constrained damping structure, the structural modal damping ratio expression is deduced by free vibration differential equation. The model that use damping material unit relative density as design variables, the structural damping ratio maximization as topology optimization goal, damping materials dosage as topology optimization constraint condition is set up. In order to obtain accurate numerical solution, the model is solved by AESO algorithm, calculating the modal damping ratio acuity to provide the best search direction for optimization iteration. According to the topology optimization criterion, damping materials is added gradually. The AESO optimization algorithm is realized by program. A numerical example shows that based on AESO method for damping structure, damping materials are mainly placed on the maximum mode strain locations of the structure. The checkerboard phenomenon is avoided. After AESO for the structure, the first order damping ratio is increased by 83.6%,while after ESO for the structure, the number is 72.13%. To verify topology optimization result, harmonic response analysis is carried out on the damping structure; the result shows that by the AESO optimization, structure vibration suppression effect is better.
In this paper, the structural damping material optimal layout is studied. Based on the principle of virtual work, the vibration differential equation of damping plate is built. According to related basic hypothesis of constrained damping structure, the structural modal damping ratio expression is deduced by free vibration differential equation. The model that use damping material unit relative density as design variables, the structural damping ratio maximization as topology optimization goal, damping materials dosage as topology optimization constraint condition is set up. In order to obtain accurate numerical solution, the model is solved by AESO algorithm, calculating the modal damping ratio acuity to provide the best search direction for optimization iteration. According to the topology optimization criterion, damping materials is added gradually. The AESO optimization algorithm is realized by program. A numerical example shows that based on AESO method for damping structure, damping materials are mainly placed on the maximum mode strain locations of the structure. The checkerboard phenomenon is avoided. After AESO for the structure, the first order damping ratio is increased by 83.6%,while after ESO for the structure, the number is 72.13%. To verify topology optimization result, harmonic response analysis is carried out on the damping structure; the result shows that by the AESO optimization, structure vibration suppression effect is better.
2017, 36(6): 978-984.
doi: 10.13433/j.cnki.1003-8728.2017.0626
Abstract:
Half-rotating wing (HRW) is a new flapping-imitating wing system with rotating-type flapping instead of oscillating-type flapping. For the complex transmission and greater weight, traditional half-rotating mechanism (HRM) is not suitable for flight. The simplified HRM with local constraint is proposed as the driving mechanism of HRW in this paper. The performing process and characteristics of local constraint was further given. According to the contact state between moving components, the performing process of local constraint was divided into four stages. The error models of half-rotating rod angle under different stages were respectively established. Case study was also given to verify the availability of error models. On the basis of analysis models mentioned above, the structural parameters of some key components were optimized to decrease rotating angle error and improve running stability of driving mechanism. The research results indicated that the simplified HRM with local constraint was useful to design driving mechanism of HRW.
Half-rotating wing (HRW) is a new flapping-imitating wing system with rotating-type flapping instead of oscillating-type flapping. For the complex transmission and greater weight, traditional half-rotating mechanism (HRM) is not suitable for flight. The simplified HRM with local constraint is proposed as the driving mechanism of HRW in this paper. The performing process and characteristics of local constraint was further given. According to the contact state between moving components, the performing process of local constraint was divided into four stages. The error models of half-rotating rod angle under different stages were respectively established. Case study was also given to verify the availability of error models. On the basis of analysis models mentioned above, the structural parameters of some key components were optimized to decrease rotating angle error and improve running stability of driving mechanism. The research results indicated that the simplified HRM with local constraint was useful to design driving mechanism of HRW.
