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RSS2016 Vol. 35, No. 3
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2016, 35(3): 329-333.
doi: 10.13433/j.cnki.1003-8728.2016.0301
PDF 2259KB
Abstract:
Based on the finite element method and stress wave theory, taking offshore marine pile hammer as the research object, the dynamic responses in pile-driving process of a marine pile hammer are discussed in this paper. By simulating the pile-driving process of the marine pile hammer with LS-dyna (a finite element analysis software), the function of the impact buffering part in the pile-driving process is analyzed. Transmission of energy between hammer and pile is also discussed and dynamic responses of important parts are predicted. Compared with the recorded results, the simulation results and analysis model are proved correct.
Based on the finite element method and stress wave theory, taking offshore marine pile hammer as the research object, the dynamic responses in pile-driving process of a marine pile hammer are discussed in this paper. By simulating the pile-driving process of the marine pile hammer with LS-dyna (a finite element analysis software), the function of the impact buffering part in the pile-driving process is analyzed. Transmission of energy between hammer and pile is also discussed and dynamic responses of important parts are predicted. Compared with the recorded results, the simulation results and analysis model are proved correct.
2016, 35(3): 334-339.
doi: 10.13433/j.cnki.1003-8728.2016.0302
Abstract:
The working principle of reverse counterboring pneumatic impactor was analyzed,and establish the differential equations of Reverse counterboring pneumatic impactor's dynamic process of internal system . Using computer simulation technology to solve differential equations, analysis and research the relationship between performance parameters-impact energy, impact frequency, piston displacement and air consumption and structure parameters-the distance from valve opening to piston and from inner piston front-end to the hammer of pneumatic percussive reverse counterboring. The corresponding simulation data and curves of structure parameters and performance parameters are obtained.
The working principle of reverse counterboring pneumatic impactor was analyzed,and establish the differential equations of Reverse counterboring pneumatic impactor's dynamic process of internal system . Using computer simulation technology to solve differential equations, analysis and research the relationship between performance parameters-impact energy, impact frequency, piston displacement and air consumption and structure parameters-the distance from valve opening to piston and from inner piston front-end to the hammer of pneumatic percussive reverse counterboring. The corresponding simulation data and curves of structure parameters and performance parameters are obtained.
2016, 35(3): 340-345.
doi: 10.13433/j.cnki.1003-8728.2016.0303
Abstract:
Aiming at solving the existing problems and shortcomings of current spiral corrugated steel machine, firstly, the weight factors between the requirements and engineering characteristics and the rate of improvement were determined with the QFD. Next method, the physical and technical conflicts were extracted according to the TRIZ method. Then the parameters, which were necessary to modify, were found out by comparing 39 parameters. Meanwhile, 40 invention principles were used to determine the feasible way to solve the problem. Thirdly, a new type of spiral corrugated steel machine was designed based on the functional requirements and structural features of corrugated steel machine. Finally, the innovation design was reasonable according to the analysis results via finite element method.
Aiming at solving the existing problems and shortcomings of current spiral corrugated steel machine, firstly, the weight factors between the requirements and engineering characteristics and the rate of improvement were determined with the QFD. Next method, the physical and technical conflicts were extracted according to the TRIZ method. Then the parameters, which were necessary to modify, were found out by comparing 39 parameters. Meanwhile, 40 invention principles were used to determine the feasible way to solve the problem. Thirdly, a new type of spiral corrugated steel machine was designed based on the functional requirements and structural features of corrugated steel machine. Finally, the innovation design was reasonable according to the analysis results via finite element method.
2016, 35(3): 346-350.
doi: 10.13433/j.cnki.1003-8728.2016.0304
Abstract:
The discrete-time transfer matrix method has obvious advantages in simulating the vibration response when adding force on the rotor and system changed with time. The high-rotor and low-rotor dynamic simplified models of gas turbine are established. Based on the discrete-time transfer matrix method,the critical speeds of the rotor are calculated. Taking two fault modes which are fluid excitation and thermal deformation for example, the vibration responses are calculated. Through experimental verification, the results are right; and the rotor dynamic model establishment method, the discrete-time transfer matrix and fault simulation method are reliable, which can be used in the rotor dynamic calculation of gas turbine directly.
The discrete-time transfer matrix method has obvious advantages in simulating the vibration response when adding force on the rotor and system changed with time. The high-rotor and low-rotor dynamic simplified models of gas turbine are established. Based on the discrete-time transfer matrix method,the critical speeds of the rotor are calculated. Taking two fault modes which are fluid excitation and thermal deformation for example, the vibration responses are calculated. Through experimental verification, the results are right; and the rotor dynamic model establishment method, the discrete-time transfer matrix and fault simulation method are reliable, which can be used in the rotor dynamic calculation of gas turbine directly.
2016, 35(3): 351-357.
doi: 10.13433/j.cnki.1003-8728.2016.0305
Abstract:
The suppression principle of coupling vibration of current-carrying plate was proposed and a structural vibration fluid attenuator was developed. The fluid pulse energy was attenuated with damping balance hole, static balance sheet vessel and plate vibration, the fluid resonance and structure resonance were combined in one attenuator. The current-carrying plate kinematics under the action of fluid coupling was analyzed with small perturbation theory. Then with the lumped parameter method, the dynamic characteristic of the attenuator was analyzed and the matrix transfer model was established, the results of simulation analysis is consistent to the theoretical model. Finally, the experimental prototype was designed and manufactured; the performance testing was carried out. Through analyzing the fluid pressure signals of time domain and frequency domain, the results show that the attenuator has good fluid pulsation attenuation effect at coupling resonance frequency points, and also has certain fluid pressure pulsation suppression effectiveness within the scope of its filter bandwidth at the same time. The correctness of theoretical analysis was validated by testing and this method provides a new way for fluid pressure pulsation suppression.
The suppression principle of coupling vibration of current-carrying plate was proposed and a structural vibration fluid attenuator was developed. The fluid pulse energy was attenuated with damping balance hole, static balance sheet vessel and plate vibration, the fluid resonance and structure resonance were combined in one attenuator. The current-carrying plate kinematics under the action of fluid coupling was analyzed with small perturbation theory. Then with the lumped parameter method, the dynamic characteristic of the attenuator was analyzed and the matrix transfer model was established, the results of simulation analysis is consistent to the theoretical model. Finally, the experimental prototype was designed and manufactured; the performance testing was carried out. Through analyzing the fluid pressure signals of time domain and frequency domain, the results show that the attenuator has good fluid pulsation attenuation effect at coupling resonance frequency points, and also has certain fluid pressure pulsation suppression effectiveness within the scope of its filter bandwidth at the same time. The correctness of theoretical analysis was validated by testing and this method provides a new way for fluid pressure pulsation suppression.
2016, 35(3): 358-363.
doi: 10.13433/j.cnki.1003-8728.2016.0306
Abstract:
Considering the sprung mass and spring stiffness perturbed problem of the high-speed train, we apply linear fractional transformation to separate the perturbation parameter from the vertical vibration model. And weighting functions are selected to design robust μ-synthesis controller according to performance requirements, whose response is compared with the robust H∞ controller based on the nominal plant model with track vertical profile irregularity as external excitation. Simulation results show that robust H∞ controller performs better in suppressing vertical vibration only with external disturbance; when the model exists parameter perturbation, robust H∞ controller leads to obvious deterioration, but the robust μ-Synthesis controller still performs good suppressing vibration ability. Robust μ-Synthesis controller ensures better robust stability and robust performance of closed-loop system in comparison with the robust H∞ controller designed based on the nominal plant model.
Considering the sprung mass and spring stiffness perturbed problem of the high-speed train, we apply linear fractional transformation to separate the perturbation parameter from the vertical vibration model. And weighting functions are selected to design robust μ-synthesis controller according to performance requirements, whose response is compared with the robust H∞ controller based on the nominal plant model with track vertical profile irregularity as external excitation. Simulation results show that robust H∞ controller performs better in suppressing vertical vibration only with external disturbance; when the model exists parameter perturbation, robust H∞ controller leads to obvious deterioration, but the robust μ-Synthesis controller still performs good suppressing vibration ability. Robust μ-Synthesis controller ensures better robust stability and robust performance of closed-loop system in comparison with the robust H∞ controller designed based on the nominal plant model.
2016, 35(3): 364-369.
doi: 10.13433/j.cnki.1003-8728.2016.0307
Abstract:
A three-dimensional mechanical model and a heat transfer mathematical model in the thermal equilibrium state were built through reasonable assumptions, and then stress and strain analysis in the rolling state was done. A simplified two-dimensional finite element model of steady-state temperature field was founded in the finite element software, and the steady-state temperature distribution inside the wheel in the rolling state was obtained by simulation calculations. Influences of the speed, loss factor of rubber materials, thermal conductivity and wheel width on the maximum temperature were researched. The regression analysis between the maximum temperature and multi-factors was built, and F distribution test and prediction cases reflect its high reliability, so it can be used to predict the maximum temperature in rolling state.
A three-dimensional mechanical model and a heat transfer mathematical model in the thermal equilibrium state were built through reasonable assumptions, and then stress and strain analysis in the rolling state was done. A simplified two-dimensional finite element model of steady-state temperature field was founded in the finite element software, and the steady-state temperature distribution inside the wheel in the rolling state was obtained by simulation calculations. Influences of the speed, loss factor of rubber materials, thermal conductivity and wheel width on the maximum temperature were researched. The regression analysis between the maximum temperature and multi-factors was built, and F distribution test and prediction cases reflect its high reliability, so it can be used to predict the maximum temperature in rolling state.
2016, 35(3): 370-374.
doi: 10.13433/j.cnki.1003-8728.2016.0308
Abstract:
The thread on the clamp pressure plate of high frequency fatigue test machine easily damaged, and which led to not remove the work-piece. In the fatigue test process of 20MnTiB bar under high frequency on the PLG-100 machine, the thread of the clamp pressure plate was damaged with the aid of a wrench repeatedly, and the work-piece was not fixed on the fatigue test machine. Then three methods to repair the pressure plate thread are presented, including embedded cylinder sleeve, sleeve of concentric cylindrical steps and the threaded sleeve in the center of the pressure plate. The fatigue test results indicated that with the repair method of threaded sleeve could complete the test requirement and the horizontal portion of fatigue life curve was obtained and convenient maintenance, rapid economy. Comparing the former two methods, the method inset threaded sleeve could improve the thread connection strength, heat resistance and abrasion resistance.
The thread on the clamp pressure plate of high frequency fatigue test machine easily damaged, and which led to not remove the work-piece. In the fatigue test process of 20MnTiB bar under high frequency on the PLG-100 machine, the thread of the clamp pressure plate was damaged with the aid of a wrench repeatedly, and the work-piece was not fixed on the fatigue test machine. Then three methods to repair the pressure plate thread are presented, including embedded cylinder sleeve, sleeve of concentric cylindrical steps and the threaded sleeve in the center of the pressure plate. The fatigue test results indicated that with the repair method of threaded sleeve could complete the test requirement and the horizontal portion of fatigue life curve was obtained and convenient maintenance, rapid economy. Comparing the former two methods, the method inset threaded sleeve could improve the thread connection strength, heat resistance and abrasion resistance.
2016, 35(3): 375-380.
doi: 10.13433/j.cnki.1003-8728.2016.0309
Abstract:
In order to weed without using chemicals, this paper designed a quadruped weeding robot. The virtual prototype model and dynamic simulation of the weeding robot was established, and the efficiency and reliability of the quadruped weeding robot were improved. After the mechanical dynamic model of the quadruped weeding robot was built with ADAMS, the ADAMS and MATLAB/Simulink co-simulation (coordinated simulation) technology was employed to set the parameters of the control system. With the method, the PID parameters and the driving force for the walking of the quadruped weeding robot are preliminarily determined. Because the ADAMS and MATLAB/Simulink co-simulation is multi-field oriented, the simulation results are approximate to reality and close to a real robot. This method paves the foundation for developing the physical prototype of a quadruped weeding robot and helps to solve the mismatching between a machine and its control system in traditional designs.
In order to weed without using chemicals, this paper designed a quadruped weeding robot. The virtual prototype model and dynamic simulation of the weeding robot was established, and the efficiency and reliability of the quadruped weeding robot were improved. After the mechanical dynamic model of the quadruped weeding robot was built with ADAMS, the ADAMS and MATLAB/Simulink co-simulation (coordinated simulation) technology was employed to set the parameters of the control system. With the method, the PID parameters and the driving force for the walking of the quadruped weeding robot are preliminarily determined. Because the ADAMS and MATLAB/Simulink co-simulation is multi-field oriented, the simulation results are approximate to reality and close to a real robot. This method paves the foundation for developing the physical prototype of a quadruped weeding robot and helps to solve the mismatching between a machine and its control system in traditional designs.
2016, 35(3): 381-385.
doi: 10.13433/j.cnki.1003-8728.2016.0310
Abstract:
To efficiently combine the multi-source evidence information on a recognition system and improve its pattern recognition accuracy, a weighted fusion method for recognizing the patterns of multi-source information is proposed. The evidence source of each proposition in the recognition framework is different, and the reliability resulting from the recognition of the proposition isn't the same. The correct rate of recognizing all the propositions can be transformed into the weighted coefficient; thus the recognition system of the weighted fusion method is constructed by improving the weighted evidence theory to reduce the uncertainty to its minimum that certainly exists during pattern recognition and to enhance the determinacy and creditability of the weighted evidence theory. The study results show that the creditability of the recognition system is obviously enhanced and that its correct rate is distinctively increased. It is verified that the weighted fusion method can effectively improve the pattern recognition accuracy.
To efficiently combine the multi-source evidence information on a recognition system and improve its pattern recognition accuracy, a weighted fusion method for recognizing the patterns of multi-source information is proposed. The evidence source of each proposition in the recognition framework is different, and the reliability resulting from the recognition of the proposition isn't the same. The correct rate of recognizing all the propositions can be transformed into the weighted coefficient; thus the recognition system of the weighted fusion method is constructed by improving the weighted evidence theory to reduce the uncertainty to its minimum that certainly exists during pattern recognition and to enhance the determinacy and creditability of the weighted evidence theory. The study results show that the creditability of the recognition system is obviously enhanced and that its correct rate is distinctively increased. It is verified that the weighted fusion method can effectively improve the pattern recognition accuracy.
2016, 35(3): 386-391.
doi: 10.13433/j.cnki.1003-8728.2016.0311
Abstract:
A compound automotive transmission is composed of a metal belt continuously variable transmission (CVT) unit and a shuttle transmission component and can realize the CVT and variable transmissions according to the automotive operation mode. To study the compound automotive transmission, the paper proposes an optimum economy ratio optimization algorithm that takes into account the efficiency of the engine of the automotive and CVT. Firstly, the mathematical model of its drivetrain was established and includes the engine output torque model of the engine and its efficiency model and CVT. Secondly, the optimum fuel economy optimization objective function was built. With SimulationX, the simulation car model of the compound automotive transmission was designed and its optimum economy ratios were optimized. By comparing the automotive dynamics and fuel economy before and after optimization, the validity of this method was verified.
A compound automotive transmission is composed of a metal belt continuously variable transmission (CVT) unit and a shuttle transmission component and can realize the CVT and variable transmissions according to the automotive operation mode. To study the compound automotive transmission, the paper proposes an optimum economy ratio optimization algorithm that takes into account the efficiency of the engine of the automotive and CVT. Firstly, the mathematical model of its drivetrain was established and includes the engine output torque model of the engine and its efficiency model and CVT. Secondly, the optimum fuel economy optimization objective function was built. With SimulationX, the simulation car model of the compound automotive transmission was designed and its optimum economy ratios were optimized. By comparing the automotive dynamics and fuel economy before and after optimization, the validity of this method was verified.
2016, 35(3): 392-395.
doi: 10.13433/j.cnki.1003-8728.2016.0312
Abstract:
For the combining gear drive with elastomeric web, the lumped parameter method is used to establish a nonlinear dynamics model of torsional vibration, and the incremental harmonic balance method is used to obtain the nonlinear dynamic responses of the system. The influence of stiffness and damping of the elastomeric web on system vibration is analyzed. Numerical results show that under different stiffnesses of the elastomeric web, system would appear harmonic response, quasi-periodic and chaotic response, which are typical nonlinear vibration characteristics; when the elastomeric web stiffness reaches 109 N/m, the systematic dynamic load factor surges to the maximum, 1.35; the effect of the elastomeric web damping on the dynamic load coefficient is also non-linear, but on the whole, the dynamic load factor decreases with the increase of the damping ratio.
For the combining gear drive with elastomeric web, the lumped parameter method is used to establish a nonlinear dynamics model of torsional vibration, and the incremental harmonic balance method is used to obtain the nonlinear dynamic responses of the system. The influence of stiffness and damping of the elastomeric web on system vibration is analyzed. Numerical results show that under different stiffnesses of the elastomeric web, system would appear harmonic response, quasi-periodic and chaotic response, which are typical nonlinear vibration characteristics; when the elastomeric web stiffness reaches 109 N/m, the systematic dynamic load factor surges to the maximum, 1.35; the effect of the elastomeric web damping on the dynamic load coefficient is also non-linear, but on the whole, the dynamic load factor decreases with the increase of the damping ratio.
2016, 35(3): 396-400.
doi: 10.13433/j.cnki.1003-8728.2016.0313
Abstract:
Aiming at the shortages of existing semi-autonomous excavator robot, a remote control scheme based on actions is proposed in this paper. On the basis of the comprehensive discussion of remote control theory, the realization of the remote control scheme for excavator is stated, and a platform has been built to verify the control scheme based on actions. The results and their analysis show preliminarly that the remote control system is not only lightweight in equipment, flexible in operating and has a good performance in tracking master-slave end. It can meet the basic requirement of remote operation of excavator, providing a reference for the development and design of excavator remote control system.
Aiming at the shortages of existing semi-autonomous excavator robot, a remote control scheme based on actions is proposed in this paper. On the basis of the comprehensive discussion of remote control theory, the realization of the remote control scheme for excavator is stated, and a platform has been built to verify the control scheme based on actions. The results and their analysis show preliminarly that the remote control system is not only lightweight in equipment, flexible in operating and has a good performance in tracking master-slave end. It can meet the basic requirement of remote operation of excavator, providing a reference for the development and design of excavator remote control system.
2016, 35(3): 401-407.
doi: 10.13433/j.cnki.1003-8728.2016.0314
Abstract:
In view of existing structural design being easy to cause the unreasonable regional distribution of stress concentration when plastic deformation,the plastic behavior of rollover protective structures when colliding the ground is researched by the finite element simulation. For domestic KZ-28 vibrator, the regular pattern for plastic deformation area of its rollover protective structure is studied; Aiming at the phenomenon of stress concentration of the structure being easy to cause joint damage, plastic hinge hole is set rationally to optimize the distribution of stress concentration; and the orthogonal experiment method is used to select the best schemes for plastic hinge hole. The simulation results indicate that the distribution of stress concentration area for the KZ-28 rollover protective structures set with plastic hinge hole is more reasonable than that without plastic hinge hole, avoiding the damage to the joints, and the overall energy absorption capacity is increased. Through setting up reasonable plastic hinge hole to improve the distribution of stress concentration area, the optimization method promotes energy absorption ability and improves the performance of structure for rollover protective structures.
In view of existing structural design being easy to cause the unreasonable regional distribution of stress concentration when plastic deformation,the plastic behavior of rollover protective structures when colliding the ground is researched by the finite element simulation. For domestic KZ-28 vibrator, the regular pattern for plastic deformation area of its rollover protective structure is studied; Aiming at the phenomenon of stress concentration of the structure being easy to cause joint damage, plastic hinge hole is set rationally to optimize the distribution of stress concentration; and the orthogonal experiment method is used to select the best schemes for plastic hinge hole. The simulation results indicate that the distribution of stress concentration area for the KZ-28 rollover protective structures set with plastic hinge hole is more reasonable than that without plastic hinge hole, avoiding the damage to the joints, and the overall energy absorption capacity is increased. Through setting up reasonable plastic hinge hole to improve the distribution of stress concentration area, the optimization method promotes energy absorption ability and improves the performance of structure for rollover protective structures.
2016, 35(3): 408-413.
doi: 10.13433/j.cnki.1003-8728.2016.0315
Abstract:
Based on the CFD theory, the flow field characteristics of coupled erosion and cavitation wear were numerically simulated in different impact angles (α7 Pa when the impact angle is about 30°, the materials are more prone to fatigue failure in this kind of repeated impact; 2) the failure of 40Cr is mainly micro-cutting furrows and some pinhole-like pits when the impact angle αα>30°. The trend between the weight loss of 40Cr specimen and its impact angle coincides with the cubic spline very well.
Based on the CFD theory, the flow field characteristics of coupled erosion and cavitation wear were numerically simulated in different impact angles (α7 Pa when the impact angle is about 30°, the materials are more prone to fatigue failure in this kind of repeated impact; 2) the failure of 40Cr is mainly micro-cutting furrows and some pinhole-like pits when the impact angle αα>30°. The trend between the weight loss of 40Cr specimen and its impact angle coincides with the cubic spline very well.
2016, 35(3): 414-419.
doi: 10.13433/j.cnki.1003-8728.2016.0316
Abstract:
The dynamic equations model of the dual-arm space robot are derived with the Lagrange method and the linear momentum conservation relations; through the adaptive adjustment of parameters to estimate the boundary of uncertainties online, we propose an improved robust control scheme based on the augmentation approach, which is different from the traditional robust control scheme. Through opening and closing the adaptive adjustments of parameters, the simulation results show that the improved robust control scheme we proposed has good control effect on and anti-disturbance capacity of enabling the dual-arm space robot with uncertainties to perform the specified joint motions of the dual-arm space robot.
The dynamic equations model of the dual-arm space robot are derived with the Lagrange method and the linear momentum conservation relations; through the adaptive adjustment of parameters to estimate the boundary of uncertainties online, we propose an improved robust control scheme based on the augmentation approach, which is different from the traditional robust control scheme. Through opening and closing the adaptive adjustments of parameters, the simulation results show that the improved robust control scheme we proposed has good control effect on and anti-disturbance capacity of enabling the dual-arm space robot with uncertainties to perform the specified joint motions of the dual-arm space robot.
2016, 35(3): 420-424.
doi: 10.13433/j.cnki.1003-8728.2016.0317
Abstract:
Disadvantages in traditional multi-stage forming of vertical walls can be summarized as complexity of process planning, long machining time consuming and severe thinning. Aiming at this situation, a new bending and stretching strategy is put forward, which consists of three stages: performing, bending and stretching and finishing for vertical walls. Experiments are carried out based on the new technology, and the result shows that: the new strategy has access to the vertical wall products with small thinning and more uniform thickness distribution in vertical wall. Furthermore, the processing time is significantly short so as to cater for production requirement; preformed angle directly determines the final wall thickness. Through increasing the preformed angle, the wall thickness is sharply declined; because of the influence of the circumferential stress, the increase in thickness occurred in local area of vertical walls, and the thickened area get larger with the decline of the preformed angle.
Disadvantages in traditional multi-stage forming of vertical walls can be summarized as complexity of process planning, long machining time consuming and severe thinning. Aiming at this situation, a new bending and stretching strategy is put forward, which consists of three stages: performing, bending and stretching and finishing for vertical walls. Experiments are carried out based on the new technology, and the result shows that: the new strategy has access to the vertical wall products with small thinning and more uniform thickness distribution in vertical wall. Furthermore, the processing time is significantly short so as to cater for production requirement; preformed angle directly determines the final wall thickness. Through increasing the preformed angle, the wall thickness is sharply declined; because of the influence of the circumferential stress, the increase in thickness occurred in local area of vertical walls, and the thickened area get larger with the decline of the preformed angle.
2016, 35(3): 425-430.
doi: 10.13433/j.cnki.1003-8728.2016.0318
Abstract:
The processing of carbon fiber reinforced composites(CFRP) is easy to produce layered, glitches, tearing and other defects. CFRP are difficult to machine. To establish a model for the ultrasonic face milling of CFRP is used to analyze the milling mechanism of CFRP under two kinds of angle. Experimental research was carried out for both the longitudinal-torsional resonance rotary ultrasonic face milling and the traditional face milling of CFRP. The experimental results showed that under the longitudinal-torsional resonance rotary ultrasonic milling conditions, CFRP surface has been processed was roughness, tool less wear. The grooves, pits were more on the processed under the conditions of normal face milling, tool seriously wear. Ultrasonic milling was better than ordinary milling.
The processing of carbon fiber reinforced composites(CFRP) is easy to produce layered, glitches, tearing and other defects. CFRP are difficult to machine. To establish a model for the ultrasonic face milling of CFRP is used to analyze the milling mechanism of CFRP under two kinds of angle. Experimental research was carried out for both the longitudinal-torsional resonance rotary ultrasonic face milling and the traditional face milling of CFRP. The experimental results showed that under the longitudinal-torsional resonance rotary ultrasonic milling conditions, CFRP surface has been processed was roughness, tool less wear. The grooves, pits were more on the processed under the conditions of normal face milling, tool seriously wear. Ultrasonic milling was better than ordinary milling.
2016, 35(3): 431-436.
doi: 10.13433/j.cnki.1003-8728.2016.0319
Abstract:
This paper presents a study on the effect of operating parameters on the pressure spike and central pressure under point contact Elastohydrodynamic Lubrication(EHL) state with a high effective iterative algorithm. Through making regression analysis for a amount of numerical results, two simple fitting formulas of pressure spike and central pressure are proposed for the operating parameters (dimensionless load, speed, and material parameter). The accuracy of the formulas is examined and it shows that in a wide range of operating parameters, the relative error between the fitting formulas and numerical solution is less 10 than percent. The current study provides a simple and useful tool for calculating maximum stress and fatigue life prediction of mechanical parts working under the point contact EHL state.
This paper presents a study on the effect of operating parameters on the pressure spike and central pressure under point contact Elastohydrodynamic Lubrication(EHL) state with a high effective iterative algorithm. Through making regression analysis for a amount of numerical results, two simple fitting formulas of pressure spike and central pressure are proposed for the operating parameters (dimensionless load, speed, and material parameter). The accuracy of the formulas is examined and it shows that in a wide range of operating parameters, the relative error between the fitting formulas and numerical solution is less 10 than percent. The current study provides a simple and useful tool for calculating maximum stress and fatigue life prediction of mechanical parts working under the point contact EHL state.
2016, 35(3): 437-443.
doi: 10.13433/j.cnki.1003-8728.2016.0320
Abstract:
The recognition of abnormal dynamic pressure wave signal is key to pipeline leakage detection and location with acoustic wave. Starting from time sequence, we propose a petroleum pipeline leakage detection and location method based on the fuzzy set theory. Firstly, an adaptive filter is designed to remove the noise of a dynamic pressure wave signal with wavelet decomposition and semi-hard and soft threshold. Secondly, the fixed-length normal dynamic pressure wave signal sequences are selected as template sequences, and the dynamic pressure wave signals with the same-length sub-sequence collected on site are selected as matching sequences; then the fuzzy sets of two sub-sequence signals' power spectra are constructed to calculate their fuzzy similarity degrees. Finally, we use the fuzzy similarity degrees to judge if petroleum pipeline leakage occurs; if yes, we locate the leakage by using the fuzzy entropy difference between normal and collected dynamic pressure wave signal sequences of the petroleum pipeline. The experimental results show that our method is simple, effective and has high location accuracy.
The recognition of abnormal dynamic pressure wave signal is key to pipeline leakage detection and location with acoustic wave. Starting from time sequence, we propose a petroleum pipeline leakage detection and location method based on the fuzzy set theory. Firstly, an adaptive filter is designed to remove the noise of a dynamic pressure wave signal with wavelet decomposition and semi-hard and soft threshold. Secondly, the fixed-length normal dynamic pressure wave signal sequences are selected as template sequences, and the dynamic pressure wave signals with the same-length sub-sequence collected on site are selected as matching sequences; then the fuzzy sets of two sub-sequence signals' power spectra are constructed to calculate their fuzzy similarity degrees. Finally, we use the fuzzy similarity degrees to judge if petroleum pipeline leakage occurs; if yes, we locate the leakage by using the fuzzy entropy difference between normal and collected dynamic pressure wave signal sequences of the petroleum pipeline. The experimental results show that our method is simple, effective and has high location accuracy.
2016, 35(3): 444-447.
doi: 10.13433/j.cnki.1003-8728.2016.0321
Abstract:
It was found that the vibration system based on the negative capacitance piezoelectric shunt damping will be unstable when the negative capacitance value is small in the experiment. Aiming at the problem, the vibration system model based on the negative capacitance piezoelectric shunt damping is derived with feedback control theory in this paper, and its stability is analyzed. Then, the experimental platform which is an alloy rectangular thin plate clamped with stiff base is set up using the dSPACE real-time simulation platform, the elements of analog circuit and piezoelectric element. Finally, experimental research is carried out in the platform. Theoretical analysis and experimental results show that the vibration control system based on the negative capacitance piezoelectric shunt damping will become unstable when the negative capacitance is smaller or slightly larger than the capacitance of the piezoelectric patch. The stability study of the piezoelectric shunt damping vibration system based on negative capacitance will have an important guiding significance for the negative capacitance applied in the vibration and noise control system.
It was found that the vibration system based on the negative capacitance piezoelectric shunt damping will be unstable when the negative capacitance value is small in the experiment. Aiming at the problem, the vibration system model based on the negative capacitance piezoelectric shunt damping is derived with feedback control theory in this paper, and its stability is analyzed. Then, the experimental platform which is an alloy rectangular thin plate clamped with stiff base is set up using the dSPACE real-time simulation platform, the elements of analog circuit and piezoelectric element. Finally, experimental research is carried out in the platform. Theoretical analysis and experimental results show that the vibration control system based on the negative capacitance piezoelectric shunt damping will become unstable when the negative capacitance is smaller or slightly larger than the capacitance of the piezoelectric patch. The stability study of the piezoelectric shunt damping vibration system based on negative capacitance will have an important guiding significance for the negative capacitance applied in the vibration and noise control system.
2016, 35(3): 448-452.
doi: 10.13433/j.cnki.1003-8728.2016.0322
Abstract:
In order to overcome the shortage of prematurity and poor astringency of conventional genetic algorithms, a modified genetic algorithm strategy was proposed and mixed with particle swarm optimization to build a hybrid genetic algorithm. The algorithm was further applied to shape optimization of the sleeve of soft release mechanism. The parameteric model of the soft release mechanism was built by using the Patran Command Language. The sleeve shape was discretized and optimized, the sleeve shape with the soft release characteristics proposed by Keepers was achieved. The optimization result shows that the proposed hybrid genetic algorithms converges faster and has better feasibility compared with conventional genetic algorithms.
In order to overcome the shortage of prematurity and poor astringency of conventional genetic algorithms, a modified genetic algorithm strategy was proposed and mixed with particle swarm optimization to build a hybrid genetic algorithm. The algorithm was further applied to shape optimization of the sleeve of soft release mechanism. The parameteric model of the soft release mechanism was built by using the Patran Command Language. The sleeve shape was discretized and optimized, the sleeve shape with the soft release characteristics proposed by Keepers was achieved. The optimization result shows that the proposed hybrid genetic algorithms converges faster and has better feasibility compared with conventional genetic algorithms.
2016, 35(3): 453-459.
doi: 10.13433/j.cnki.1003-8728.2016.0323
Abstract:
The strength design of vehicle suspension key fastener is mainly dependent on empirical formula currently, thus it is difficult to ensure the reliability of design. How to ensure adequate strength of fastener has been the key problem of key fastener design and selection. Firstly, four analytical models of longitudinal, lateral, vertical and composite vehicle models under extreme conditions were established. Parameters of vehicle model were modified according toteh results of road testing, and tire forces were solved by using numerical methods. Then the suspension model in the ADAMS software was improved, and the key fastener forces under each extreme condition were obtained based on computer simulations.Finally, the strength design and selection for key fasteners were executed according to the maximum force. Application examples show that this design method is able to guarantee the strength design and selection of suspension key fastener with sufficient reliability and it meets the requirements of each extreme condition.
The strength design of vehicle suspension key fastener is mainly dependent on empirical formula currently, thus it is difficult to ensure the reliability of design. How to ensure adequate strength of fastener has been the key problem of key fastener design and selection. Firstly, four analytical models of longitudinal, lateral, vertical and composite vehicle models under extreme conditions were established. Parameters of vehicle model were modified according toteh results of road testing, and tire forces were solved by using numerical methods. Then the suspension model in the ADAMS software was improved, and the key fastener forces under each extreme condition were obtained based on computer simulations.Finally, the strength design and selection for key fasteners were executed according to the maximum force. Application examples show that this design method is able to guarantee the strength design and selection of suspension key fastener with sufficient reliability and it meets the requirements of each extreme condition.
2016, 35(3): 460-464.
doi: 10.13433/j.cnki.1003-8728.2016.0324
Abstract:
For exploring vibration characteristics of car body-in-white susceptible to the influence of spot weld layout(SWL), a variable density topology combinatorial optimization method was applied to the SWL design, which would improve structural resonance problems. Firstly, the key principal components easy to effect low order modal frequency of car body-in-white were determined. Then an automotive body is partitioned into several different functional domains. Finally, the variable density analysis based topology optimization method was developed for optimal SWL design of car body-in-white. Combined with the welding process of car body-in-white, the topology optimization of SWL design was performed with inherent low frequency vibration characteristics as the optimization goal, the minimum volume of spot welds as boundary constrain and the material density as design variable. Modal analysis results showed that the number of spot weld after topology combinatorial optimization has reduced by 2.38%, and the first-order modal frequency of car body-in-white is 27.53 Hz, which is increased by 1.28 Hz. Consequently the variable structure control based topology optimization method used in SWL design of car body-in-white can determine the best layout of spot weld of car body-in-white and decrease the possibility of structural resonance in idle condition.
For exploring vibration characteristics of car body-in-white susceptible to the influence of spot weld layout(SWL), a variable density topology combinatorial optimization method was applied to the SWL design, which would improve structural resonance problems. Firstly, the key principal components easy to effect low order modal frequency of car body-in-white were determined. Then an automotive body is partitioned into several different functional domains. Finally, the variable density analysis based topology optimization method was developed for optimal SWL design of car body-in-white. Combined with the welding process of car body-in-white, the topology optimization of SWL design was performed with inherent low frequency vibration characteristics as the optimization goal, the minimum volume of spot welds as boundary constrain and the material density as design variable. Modal analysis results showed that the number of spot weld after topology combinatorial optimization has reduced by 2.38%, and the first-order modal frequency of car body-in-white is 27.53 Hz, which is increased by 1.28 Hz. Consequently the variable structure control based topology optimization method used in SWL design of car body-in-white can determine the best layout of spot weld of car body-in-white and decrease the possibility of structural resonance in idle condition.
2016, 35(3): 465-471.
doi: 10.13433/j.cnki.1003-8728.2016.0325
Abstract:
A regenerative braking control strategy was designed for an independent four wheel drive electric vehicle. Full consideration of factors of influence such as the vehicle's speed, state of charge of its battery, its maximum charge current and charge voltage and the torque characteristics of the electric motor, the braking curve and ECE regulation curve of the vehicle. The control strategy balances the braking stability and the recovery efficiency of braking energy. The modeling and collaborative simulation are performed with the software platforms of Simulink and AVL Cruise. The simulation results show that under the precondition of braking safety and stability, the control strategy greatly improves the recovery efficiency of braking energy.
A regenerative braking control strategy was designed for an independent four wheel drive electric vehicle. Full consideration of factors of influence such as the vehicle's speed, state of charge of its battery, its maximum charge current and charge voltage and the torque characteristics of the electric motor, the braking curve and ECE regulation curve of the vehicle. The control strategy balances the braking stability and the recovery efficiency of braking energy. The modeling and collaborative simulation are performed with the software platforms of Simulink and AVL Cruise. The simulation results show that under the precondition of braking safety and stability, the control strategy greatly improves the recovery efficiency of braking energy.
2016, 35(3): 472-476.
doi: 10.13433/j.cnki.1003-8728.2016.0326
Abstract:
As an elastic-brittle material, the fiber ply orientation of carbon fiber reinforced plastics (CFRP) shows close relationship with the material properties, the cutting mechanism and the machining quality. The cutting process of CFRP is a very complex process of elastic-brittle fracture. In this paper, the finite element simulation of cutting and destruction of the composite with Abaqus/Explicit software are studied, and the two-dimension orthogonal cutting model is created with Hashin failure criteria. Based on the model, the cutting process and the damage mechanism under different fiber orientations are studied. The experiment is also performed to confirm the validity of the model.
As an elastic-brittle material, the fiber ply orientation of carbon fiber reinforced plastics (CFRP) shows close relationship with the material properties, the cutting mechanism and the machining quality. The cutting process of CFRP is a very complex process of elastic-brittle fracture. In this paper, the finite element simulation of cutting and destruction of the composite with Abaqus/Explicit software are studied, and the two-dimension orthogonal cutting model is created with Hashin failure criteria. Based on the model, the cutting process and the damage mechanism under different fiber orientations are studied. The experiment is also performed to confirm the validity of the model.
2016, 35(3): 477-483.
doi: 10.13433/j.cnki.1003-8728.2016.0327
Abstract:
A new model of rough surfaces based on wavelets is proposed, which can generate isotropic and anisotropic Gaussian rough surfaces. The accuracy and effectiveness of the surface simulation method is verified by means of calculating the statistic parameters and autocorrelation functions of simulated rough surfaces. With combination of Johnson translator system, this model can simulate non-Gaussian rough surfaces with given skewness and kurtosis. The results and their analysis show preliminarily that this method can adequately produce rough surfaces whose statistical characteristics match the prescribed values. Furthermore, the three-dimensional bearing area curve is defined, and it is better than the two-dimensional one. In addition, the micro-asperity curve and micro-cavity curve presently defined can provide the foundation for the further research on the micro-lubrication, micro-friction and micro-wear.
A new model of rough surfaces based on wavelets is proposed, which can generate isotropic and anisotropic Gaussian rough surfaces. The accuracy and effectiveness of the surface simulation method is verified by means of calculating the statistic parameters and autocorrelation functions of simulated rough surfaces. With combination of Johnson translator system, this model can simulate non-Gaussian rough surfaces with given skewness and kurtosis. The results and their analysis show preliminarily that this method can adequately produce rough surfaces whose statistical characteristics match the prescribed values. Furthermore, the three-dimensional bearing area curve is defined, and it is better than the two-dimensional one. In addition, the micro-asperity curve and micro-cavity curve presently defined can provide the foundation for the further research on the micro-lubrication, micro-friction and micro-wear.
2016, 35(3): 484-488.
doi: 10.13433/j.cnki.1003-8728.2016.0328
Abstract:
For repairing the damaged structure with bonded composite patches, the bondline plays a role of transferring load, its stress state significantly affect the repair results. Both the analytical and numerical methods for forecasting the stress distribution in the bondline are developed in this paper. The analytical results was in a good agreement with the FEM result, which verified the validity of the present model. At last, the effect of the repair parameters on the stress distribution of the bondline was discussed. The results and their analysis showed preliminarily that the increase in patch length and patch thickness can slightly enhance the capacity of patch to share the load, the increase in thickness and the decrease in shear modulus of the bondline could decrease the shear stress.
For repairing the damaged structure with bonded composite patches, the bondline plays a role of transferring load, its stress state significantly affect the repair results. Both the analytical and numerical methods for forecasting the stress distribution in the bondline are developed in this paper. The analytical results was in a good agreement with the FEM result, which verified the validity of the present model. At last, the effect of the repair parameters on the stress distribution of the bondline was discussed. The results and their analysis showed preliminarily that the increase in patch length and patch thickness can slightly enhance the capacity of patch to share the load, the increase in thickness and the decrease in shear modulus of the bondline could decrease the shear stress.
2016, 35(3): 489-492.
doi: 10.13433/j.cnki.1003-8728.2016.0329
Abstract:
The detail fatigue rating (DFR) values of Al-Li-S-4 and 2524-T3 aluminum alloy structures are measured by fatigue experiments of riveted lap joints. The fatigue crack initiation and propagation behavior are observed by scanning electron microscopy. The results indicate that the DFR value of Al-Li-S-4 alloy is 102.24 MPa and the 2198-T8 alloy is 83.09 MPa, so the former has superior fatigue properties to the latter. There are some differences between Al-Li-S-4 and 2198-T8 on the fatigue fractography, and the former is flat and the latter is relatively rough, and the interval of fatigue striations of Al-Li-S-4 material is closer and finer.
The detail fatigue rating (DFR) values of Al-Li-S-4 and 2524-T3 aluminum alloy structures are measured by fatigue experiments of riveted lap joints. The fatigue crack initiation and propagation behavior are observed by scanning electron microscopy. The results indicate that the DFR value of Al-Li-S-4 alloy is 102.24 MPa and the 2198-T8 alloy is 83.09 MPa, so the former has superior fatigue properties to the latter. There are some differences between Al-Li-S-4 and 2198-T8 on the fatigue fractography, and the former is flat and the latter is relatively rough, and the interval of fatigue striations of Al-Li-S-4 material is closer and finer.
