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RSS2014 Vol. 33, No. 3
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2014, 33(3): 313-316.
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Abstract:
This paper develops a multi-objective optimization model of the continuum structure. The objectives ofthe model are to maximize the fundamental frequency of the continuum structure and minimize its compliance. Therational approximation of material properties method is adopted to ensure the clear topology of the continuum structure; the design objectives and material distribution are controlled by the optimization criteria method; the checkerboard influence was eliminated by the sensitivity filtering method. To improve the smoothness of the objective function and avoid the singularity of numerical computation, the weighted objective function is normalized. The numerical simulation produces the effects of the weighted coefficient of the static and dynamic optimization on the topology form and objective values (the fundamental frequency of the continuum structure and its compliance). The simulation results indicate that the method proposed in the paper is effective.
This paper develops a multi-objective optimization model of the continuum structure. The objectives ofthe model are to maximize the fundamental frequency of the continuum structure and minimize its compliance. Therational approximation of material properties method is adopted to ensure the clear topology of the continuum structure; the design objectives and material distribution are controlled by the optimization criteria method; the checkerboard influence was eliminated by the sensitivity filtering method. To improve the smoothness of the objective function and avoid the singularity of numerical computation, the weighted objective function is normalized. The numerical simulation produces the effects of the weighted coefficient of the static and dynamic optimization on the topology form and objective values (the fundamental frequency of the continuum structure and its compliance). The simulation results indicate that the method proposed in the paper is effective.
2014, 33(3): 317-321.
Abstract:
In order to study double bottom structure Sevan offshore oil platform dynamic response in the South China Sea, SEVAN 650 platform models had been built by using the ANSYS software, and then the models were imported into hydrodynamic analysis software AQWA for numerical calculation. The heave, roll and pitch response amplitude operators in the South China Sea storm survival condition were obtained for platform dynamic response characteristics. The heave, roll and pitch natural periods of single bottom structure are below double bottom structure. Both the natural period and the maximum heave response amplitude gradually increase with the increasing of double bottom platform diameter, and the maximum roll and pitch response amplitude first increase in the peak of diameter 87.5m and then decrease. Due to the diameter 85m platform natural period is far away from the storm situation wave period, the diameter 85m platform meets the production operations in the South China Sea.
In order to study double bottom structure Sevan offshore oil platform dynamic response in the South China Sea, SEVAN 650 platform models had been built by using the ANSYS software, and then the models were imported into hydrodynamic analysis software AQWA for numerical calculation. The heave, roll and pitch response amplitude operators in the South China Sea storm survival condition were obtained for platform dynamic response characteristics. The heave, roll and pitch natural periods of single bottom structure are below double bottom structure. Both the natural period and the maximum heave response amplitude gradually increase with the increasing of double bottom platform diameter, and the maximum roll and pitch response amplitude first increase in the peak of diameter 87.5m and then decrease. Due to the diameter 85m platform natural period is far away from the storm situation wave period, the diameter 85m platform meets the production operations in the South China Sea.
2014, 33(3): 322-325.
Abstract:
In order to accurately analyze the structural stress of an elastic contact pin, we combine the elastic contact stress stiffness matrix with the Hertz elastic contact theory. Considering the structure of the elastic contact pin in its working condition and the contact mutation characteristics, we use the contact stiffness matrix to derive the contact state equation. Then we establish the structural stress equations of the elastic contact pin with the Hertz elastic contact theory. We apply the elastic contact stress equations to calculating the elastic contact stress of the pin structure of a certain type of hydraulic support. The results of comparison with the finite element analysis of elastic contact stress show that our solution is correct for calculating the elastic contact stress of a pin structure.
In order to accurately analyze the structural stress of an elastic contact pin, we combine the elastic contact stress stiffness matrix with the Hertz elastic contact theory. Considering the structure of the elastic contact pin in its working condition and the contact mutation characteristics, we use the contact stiffness matrix to derive the contact state equation. Then we establish the structural stress equations of the elastic contact pin with the Hertz elastic contact theory. We apply the elastic contact stress equations to calculating the elastic contact stress of the pin structure of a certain type of hydraulic support. The results of comparison with the finite element analysis of elastic contact stress show that our solution is correct for calculating the elastic contact stress of a pin structure.
2014, 33(3): 326-331.
Abstract:
Based on the background of rotary platform of launching tower, the continuum method based on rigidity equivalent principle and mass equivalent principle is used to simplify the truss structure into an uniform solid cantilever beam rotating around a fixed point, which makes it possible to establish the damped vibration equation with assumed mode method and numerical analysis. The agreement between the calculated results and the test results demonstrate that the proposed method of this paper is available in the vibration analysis of cantilever truss structure.
Based on the background of rotary platform of launching tower, the continuum method based on rigidity equivalent principle and mass equivalent principle is used to simplify the truss structure into an uniform solid cantilever beam rotating around a fixed point, which makes it possible to establish the damped vibration equation with assumed mode method and numerical analysis. The agreement between the calculated results and the test results demonstrate that the proposed method of this paper is available in the vibration analysis of cantilever truss structure.
2014, 33(3): 332-338.
Abstract:
Although the increasingly high demand of users for wheelchair comfort, wheelchair manufactures usually focus only on how to adapt to people in the functions of the wheelchair itself, there are still many inadequacies in the wheelchair comfort, and it is a multi-layered, multi-factor problem. After a preliminary development, expert advice, information feedback, statistical processing and the synthesis for wheelchair comfort, an evaluation index system and evaluation criteria of common wheelchair comfort is built, and then the weights of the indicators at all levels are determined by the method of analytic hierarchy process in this paper. Finished comfort evaluation tests for four wheelchairs, and the overall scores for wheelchair comfort are calculated. The results show that the scores calculated on the evaluation system are closed to the subjective evaluation score.
Although the increasingly high demand of users for wheelchair comfort, wheelchair manufactures usually focus only on how to adapt to people in the functions of the wheelchair itself, there are still many inadequacies in the wheelchair comfort, and it is a multi-layered, multi-factor problem. After a preliminary development, expert advice, information feedback, statistical processing and the synthesis for wheelchair comfort, an evaluation index system and evaluation criteria of common wheelchair comfort is built, and then the weights of the indicators at all levels are determined by the method of analytic hierarchy process in this paper. Finished comfort evaluation tests for four wheelchairs, and the overall scores for wheelchair comfort are calculated. The results show that the scores calculated on the evaluation system are closed to the subjective evaluation score.
2014, 33(3): 339-343.
Abstract:
In order to discuss the temperature feature of disc, the temperature under high energy density condition is investigated based on the multi-plate wet clutch. The convective effects of cooling oil and air are analyzed based on the heat conduction theory and numerical model for heat transfer in the emergency braking is established. The transient temperature distribution in the engagement process is simulated via FEM, Then the influencing factors on the temperature field are discussed by investigating the parameters of anisotropic thermal conductivity, relative rotary speed，engaging time. The present results show that the highest temperature of engagement face of disc appears in the outside of pitch diameter; anisotropic thermal conductivity primarily affects the temperature of the engagement face of disc rather than the location far away from it; higher relative rotary speed results in higher temperature on engagement face, at the speed difference reaches 4000r /min or above and the engaging time is less than 0.8s, the max temperature will exceed 400℃ so as to cause high temperature ablation. Under the same rotary speed difference, to decrease in the engaging time will accelerate the temperature drop at its later engagement stage.
In order to discuss the temperature feature of disc, the temperature under high energy density condition is investigated based on the multi-plate wet clutch. The convective effects of cooling oil and air are analyzed based on the heat conduction theory and numerical model for heat transfer in the emergency braking is established. The transient temperature distribution in the engagement process is simulated via FEM, Then the influencing factors on the temperature field are discussed by investigating the parameters of anisotropic thermal conductivity, relative rotary speed，engaging time. The present results show that the highest temperature of engagement face of disc appears in the outside of pitch diameter; anisotropic thermal conductivity primarily affects the temperature of the engagement face of disc rather than the location far away from it; higher relative rotary speed results in higher temperature on engagement face, at the speed difference reaches 4000r /min or above and the engaging time is less than 0.8s, the max temperature will exceed 400℃ so as to cause high temperature ablation. Under the same rotary speed difference, to decrease in the engaging time will accelerate the temperature drop at its later engagement stage.
2014, 33(3): 344-347.
Abstract:
There are big differences in reserving and expressing modes of modal data from different simulation analysis softwares. In order to achieve modal information sharing and interaction in heterogeneous platforms, a reusing method on modal data is proposed in this paper. Based on this method, the modal data can be displayed and analyzed in a relatively open environment. The structural characteristics of modal data are analyzed, the heterogeneous data from different softwares is structurally processed and stored in database, and the reusing method on modal data has been investigated. Finally, a new modal display control has been developed based on DirectX technology in VB.NET environment.
There are big differences in reserving and expressing modes of modal data from different simulation analysis softwares. In order to achieve modal information sharing and interaction in heterogeneous platforms, a reusing method on modal data is proposed in this paper. Based on this method, the modal data can be displayed and analyzed in a relatively open environment. The structural characteristics of modal data are analyzed, the heterogeneous data from different softwares is structurally processed and stored in database, and the reusing method on modal data has been investigated. Finally, a new modal display control has been developed based on DirectX technology in VB.NET environment.
2014, 33(3): 348-353.
Abstract:
The requirements of carrying capacity, cavity pressure and low frequency performance for air-spring of GVT are especially strict. An approximate expression of the vertical frequency was deduced for such air-spring considering the low frequency characteristics. Based on the qualitative analysis, it was found that the vertical frequency was only decided by the geometric properties of the air-spring. A parameterized FE model of main structure of a gas tank was built by using the ABAQUS software and then the Air-spring Shape was optimizated so as to minimize the mass of gas tank by constraining the low frequency performance, strength and stiffness of the main structure of gas tank. The results showed that the optimized structure mass was greatly decreased. The present optimization method could be adopted for designing the GVT air-spring with different loading capabilities.
The requirements of carrying capacity, cavity pressure and low frequency performance for air-spring of GVT are especially strict. An approximate expression of the vertical frequency was deduced for such air-spring considering the low frequency characteristics. Based on the qualitative analysis, it was found that the vertical frequency was only decided by the geometric properties of the air-spring. A parameterized FE model of main structure of a gas tank was built by using the ABAQUS software and then the Air-spring Shape was optimizated so as to minimize the mass of gas tank by constraining the low frequency performance, strength and stiffness of the main structure of gas tank. The results showed that the optimized structure mass was greatly decreased. The present optimization method could be adopted for designing the GVT air-spring with different loading capabilities.
2014, 33(3): 354-360.
Abstract:
The working principle and flow characteristics of postmixed jet flow comminuting technology are introduced in this paper. Combining with the methods of theoretical analysis，numerical calculation and grinding experiments, the effect of accelerating pipe size on jet characteristics and its grinding mechanism are investigated based on the multi-phase mixture coupled flow characteristics in the accelerating pipe which is composed of gas, streamand liquid. Researches show that accelerating tube diameter has significant influence on the jet flow characteristics and grinding efficiency. By using the acceleration zone theory, the characteristic parameters of each acceleration region are fixed quantity. The smaller the accelerating tube diameter is, the better the result on the energy constraint of jet is; and the larger the diameter is, the lower the grinding efficiency is. The higher grinding efficiency will be obtained when the particles are close to or into the jet high-efficient acceleration zone.
The working principle and flow characteristics of postmixed jet flow comminuting technology are introduced in this paper. Combining with the methods of theoretical analysis，numerical calculation and grinding experiments, the effect of accelerating pipe size on jet characteristics and its grinding mechanism are investigated based on the multi-phase mixture coupled flow characteristics in the accelerating pipe which is composed of gas, streamand liquid. Researches show that accelerating tube diameter has significant influence on the jet flow characteristics and grinding efficiency. By using the acceleration zone theory, the characteristic parameters of each acceleration region are fixed quantity. The smaller the accelerating tube diameter is, the better the result on the energy constraint of jet is; and the larger the diameter is, the lower the grinding efficiency is. The higher grinding efficiency will be obtained when the particles are close to or into the jet high-efficient acceleration zone.
2014, 33(3): 361-365.
Abstract:
Based on the quality function deployment (QFD) , the relationship between the design and manufacturability of product was studied. The translation model for the manufacturing requirements and the hierarchy model for each design stage were presented, and the requirements of product manufacturability were translated into the performance of design elements, then the design goal was adjusted and optimized.
Based on the quality function deployment (QFD) , the relationship between the design and manufacturability of product was studied. The translation model for the manufacturing requirements and the hierarchy model for each design stage were presented, and the requirements of product manufacturability were translated into the performance of design elements, then the design goal was adjusted and optimized.
2014, 33(3): 366-371.
Abstract:
A simulation platform of wind turbine drive train is designed based on the design requirement of large multi － MW wind turbine. The platform consists of a simulation system of rotor torque input and a simulation system of wind turbine. The input torque of the simulation rotor and the load of the simulation wind turbine are controlled by the computer simulation programs. The wind turbine simulation system consists of the main bearings, gearbox，tower and other key components of the wind turbine. The pulsating torque caused by wind shear effect and tower shadow effect are added into the actual control program of the rotor input torque by the computer simulation program. The results show that the platform can simulate the wind turbine operating conditions effectively, it can be used to study the control of the wind turbine and the fault diagnosis of the drive train.
A simulation platform of wind turbine drive train is designed based on the design requirement of large multi － MW wind turbine. The platform consists of a simulation system of rotor torque input and a simulation system of wind turbine. The input torque of the simulation rotor and the load of the simulation wind turbine are controlled by the computer simulation programs. The wind turbine simulation system consists of the main bearings, gearbox，tower and other key components of the wind turbine. The pulsating torque caused by wind shear effect and tower shadow effect are added into the actual control program of the rotor input torque by the computer simulation program. The results show that the platform can simulate the wind turbine operating conditions effectively, it can be used to study the control of the wind turbine and the fault diagnosis of the drive train.
2014, 33(3): 372-377.
Abstract:
Using servo motor driving system to replace the traditional mechanical transmission is an effective way to innovate mechanical products. Aim at the slider-cam separation device of packing machinery, a design method of servo driving instead of mechanical transmission is proposed. The three dimensional dynamics analysis model of the slider-cam separation device is established. The dynamics analysis of slider-cam separation device is conduct by using virtual prototyping technology and its drive torque is calculated. According to the selection rules of the servomotor, the mathematical model of slider-cam separation device is also built, and the curve of the slider control cam has been optimized. As a result, the max torque and average torque of slider-cam separation device have been reduced remarkably, thus the requirements for the servo motor performance can be reduced.
Using servo motor driving system to replace the traditional mechanical transmission is an effective way to innovate mechanical products. Aim at the slider-cam separation device of packing machinery, a design method of servo driving instead of mechanical transmission is proposed. The three dimensional dynamics analysis model of the slider-cam separation device is established. The dynamics analysis of slider-cam separation device is conduct by using virtual prototyping technology and its drive torque is calculated. According to the selection rules of the servomotor, the mathematical model of slider-cam separation device is also built, and the curve of the slider control cam has been optimized. As a result, the max torque and average torque of slider-cam separation device have been reduced remarkably, thus the requirements for the servo motor performance can be reduced.
2014, 33(3): 378-382.
Abstract:
There is a broad prospect on the smart constrained layer damping (SCLD) structural vibration control.The performance of controller has a significant control effect. The advantage of robust H∞ control is its good robustness in the condition of many uncertainty factors. However, the finite element model of SCLD has large number of degrees of freedom and the number of sensors in experiments is limited. Thus it is difficult to achieve a control strategy which taking into account both of the system robustness and control effect. Fuzzy control is more flexible because it is designed depending on the experience of researchers and repeated debug during experiment. Combining with weighed robust H∞ algorithm, satisfactory control result is realized which is better than that by using H∞ control alone. Experimental results show that the fuzzy robust H∞ control has good control effect on acceleration response and the suppression efficiency is greater than 5dB. This study has reference significance to searching for good performance of SCLD controller.
There is a broad prospect on the smart constrained layer damping (SCLD) structural vibration control.The performance of controller has a significant control effect. The advantage of robust H∞ control is its good robustness in the condition of many uncertainty factors. However, the finite element model of SCLD has large number of degrees of freedom and the number of sensors in experiments is limited. Thus it is difficult to achieve a control strategy which taking into account both of the system robustness and control effect. Fuzzy control is more flexible because it is designed depending on the experience of researchers and repeated debug during experiment. Combining with weighed robust H∞ algorithm, satisfactory control result is realized which is better than that by using H∞ control alone. Experimental results show that the fuzzy robust H∞ control has good control effect on acceleration response and the suppression efficiency is greater than 5dB. This study has reference significance to searching for good performance of SCLD controller.
2014, 33(3): 383-386.
Abstract:
Solar energy is one of the most promising new energy resources, but currently the application of solar energy is still not ideal, mainly due to its low transformation efficiency and high operation cost. Precisely tracking the sun motion can allow the utilization of solar energy to be improved and broaden its use field. In this paper, a sidepull tracking device based on oblique single-axis is developed, which is capable of achieving a continuous tracking of the sun's rays. Comparing the side-pull tracking system with fixed installation power generation, it found that the power generation of side-pull tracking system is increased by 27.8% than the fixed one. The energy consumption of tracking system is 0.207kW穐, only 3.2% of total electricity production. The maximum power of stepper motor in side-pull tracking system is 12 W, accounting for 0.34% of the power of the entire PV module. This side-pull tracking system can significantly improve the solar power generation efficiency, which is conducive to the promotion of the solar energy application due to its low cost.
Solar energy is one of the most promising new energy resources, but currently the application of solar energy is still not ideal, mainly due to its low transformation efficiency and high operation cost. Precisely tracking the sun motion can allow the utilization of solar energy to be improved and broaden its use field. In this paper, a sidepull tracking device based on oblique single-axis is developed, which is capable of achieving a continuous tracking of the sun's rays. Comparing the side-pull tracking system with fixed installation power generation, it found that the power generation of side-pull tracking system is increased by 27.8% than the fixed one. The energy consumption of tracking system is 0.207kW穐, only 3.2% of total electricity production. The maximum power of stepper motor in side-pull tracking system is 12 W, accounting for 0.34% of the power of the entire PV module. This side-pull tracking system can significantly improve the solar power generation efficiency, which is conducive to the promotion of the solar energy application due to its low cost.
2014, 33(3): 387-390.
Abstract:
In order to solve the problem of quality detection on batch drilling, after collecting the acoustic emission signal during the working step process, a higher-order spectrum analysis method based on acoustic emission signal is proposed in this paper. According to the hypothesis that the characteristics of acoustic emission signal of an normal drilling process meet the criteria of Gaussian distribution, the wavelet packet method was used to realize de-noising for the acquired acoustic emission signals, and then the bi-spectrum slice of the acoustic emission signal from the batch drilling process was calculated one by one, the statistical dispersion deviated from the Gaussian distribution of these bi-spectrum slices could be obtained. Finally the mapping relationship between the dispersion and the drilling step quality was built to inspect the batch drilling quality. Experimental results and analysis show that the bi-spectrum slice of the acoustic emission signal can be used to identify the unqualified product on batch drilling effectively.
In order to solve the problem of quality detection on batch drilling, after collecting the acoustic emission signal during the working step process, a higher-order spectrum analysis method based on acoustic emission signal is proposed in this paper. According to the hypothesis that the characteristics of acoustic emission signal of an normal drilling process meet the criteria of Gaussian distribution, the wavelet packet method was used to realize de-noising for the acquired acoustic emission signals, and then the bi-spectrum slice of the acoustic emission signal from the batch drilling process was calculated one by one, the statistical dispersion deviated from the Gaussian distribution of these bi-spectrum slices could be obtained. Finally the mapping relationship between the dispersion and the drilling step quality was built to inspect the batch drilling quality. Experimental results and analysis show that the bi-spectrum slice of the acoustic emission signal can be used to identify the unqualified product on batch drilling effectively.
2014, 33(3): 391-394.
Abstract:
Incorporating the Visual Basic6.0 and ANSYS software, the finite element analysis system of reducer box is developed via parameterized 3D method. The friendly, conveniently and easily user interface is developed with the help of the Visual Basic 6.0. Design and analysis for the reducer box is extremely reduced by mean of the developing complex and difficult ANSYS commands, Users simply input the basic analysis parameters and load parameters of the reducer box model. The present system can automatically generate APDL commands. To call the analysis procedures of finite element method in the background and to complete static analysis and modal analysis of the reducer box. Finally the user interest and easy-to-view analysis results are getten and the efficiency of engineering design is raised.
Incorporating the Visual Basic6.0 and ANSYS software, the finite element analysis system of reducer box is developed via parameterized 3D method. The friendly, conveniently and easily user interface is developed with the help of the Visual Basic 6.0. Design and analysis for the reducer box is extremely reduced by mean of the developing complex and difficult ANSYS commands, Users simply input the basic analysis parameters and load parameters of the reducer box model. The present system can automatically generate APDL commands. To call the analysis procedures of finite element method in the background and to complete static analysis and modal analysis of the reducer box. Finally the user interest and easy-to-view analysis results are getten and the efficiency of engineering design is raised.
2014, 33(3): 395-398.
Abstract:
The dynamic analysis of engine's piston-cylinder-ring assembly is carried out by the special simulationsoftware for engine-AVL_EXCITE, and the piston slap parameter in cylinder and the piston's impact force against cylinder are obtained. The prediction estimation method for the wear of engine piston profile is proposed and then prediction simulation is conducted. On the basis of the simulation results, the contact state of the piston with cylinder liner is calculated, and the contact force acting on the surface of piston is obtained. Consequently, the wear state of piston is simulated according to the contact force. The results of simulation show that the piston's slap motion parameters and the wear state can be accurately predicted in different gap.
The dynamic analysis of engine's piston-cylinder-ring assembly is carried out by the special simulationsoftware for engine-AVL_EXCITE, and the piston slap parameter in cylinder and the piston's impact force against cylinder are obtained. The prediction estimation method for the wear of engine piston profile is proposed and then prediction simulation is conducted. On the basis of the simulation results, the contact state of the piston with cylinder liner is calculated, and the contact force acting on the surface of piston is obtained. Consequently, the wear state of piston is simulated according to the contact force. The results of simulation show that the piston's slap motion parameters and the wear state can be accurately predicted in different gap.
2014, 33(3): 399-403.
Abstract:
In order to improve the reliability level, the failure mode, effect and criticality analysis (FMECA) is performed for a controllable pitch propeller. Fault propagation net is constructed by considering fault correlation. The matrix decision method was incorporated with failure mode, effect and criticality analysis, and the existing criticality calculating method was improved and optimized. By analyzing the effect of performance degradation or failure of local cell on other cells of the system, the hazard rating of local cell fault to the entire system was determined.The proposed method overcomes the defect of existing criticality calculating method in which the fault correlation analysis and the fault propagation effects are ignored.
In order to improve the reliability level, the failure mode, effect and criticality analysis (FMECA) is performed for a controllable pitch propeller. Fault propagation net is constructed by considering fault correlation. The matrix decision method was incorporated with failure mode, effect and criticality analysis, and the existing criticality calculating method was improved and optimized. By analyzing the effect of performance degradation or failure of local cell on other cells of the system, the hazard rating of local cell fault to the entire system was determined.The proposed method overcomes the defect of existing criticality calculating method in which the fault correlation analysis and the fault propagation effects are ignored.
2014, 33(3): 404-408.
Abstract:
The car driver requires different assistance of electric power steering (EPS) while vehicle running at different speeds. The speed correlation coefficient reflects the relationship between the speed and the assistance, and affects the design of EPS assistantance curve. The speed correlation coefficient at several speeds is evaluated, and the formula of speed correlation coefficient is computed by using the cftool. The model of vehicle was firstly constructed based n the ADAMS /CAR, and the comparison between the experiment curves of vehicle with and without EPS are also carried out by using the co-simulation of MATLAB. The result showed that the minivan's portability, return ability and transient response are all improved and the rationality of the speed correlation coefficient design are verified.
The car driver requires different assistance of electric power steering (EPS) while vehicle running at different speeds. The speed correlation coefficient reflects the relationship between the speed and the assistance, and affects the design of EPS assistantance curve. The speed correlation coefficient at several speeds is evaluated, and the formula of speed correlation coefficient is computed by using the cftool. The model of vehicle was firstly constructed based n the ADAMS /CAR, and the comparison between the experiment curves of vehicle with and without EPS are also carried out by using the co-simulation of MATLAB. The result showed that the minivan's portability, return ability and transient response are all improved and the rationality of the speed correlation coefficient design are verified.
2014, 33(3): 409-412.
Abstract:
Based on the example of brake condition, the structural strength calculation and modal analysis of thesubframe are carried out via co-simulation of ANSYS-ADAMS /Car. According to the static calculation and material allowable strength analysis, modal frequency and vibration frequency analysis, ti is verified that the strength and the dynamic performance of subframe meet the requirements. The present method has an important reference value and instructive significance for rducing cycle times and improving the design of the subframe.
Based on the example of brake condition, the structural strength calculation and modal analysis of thesubframe are carried out via co-simulation of ANSYS-ADAMS /Car. According to the static calculation and material allowable strength analysis, modal frequency and vibration frequency analysis, ti is verified that the strength and the dynamic performance of subframe meet the requirements. The present method has an important reference value and instructive significance for rducing cycle times and improving the design of the subframe.
2014, 33(3): 413-418.
Abstract:
Considering the wide variation range of load when it is running and the convenience of operation for the driver, the coefficient of colligation for the driver was introduced, and a comprehensive shift schedule with the parameters of weight and throttle was proposed based on the traditional dynamic and economic shifting schedules by using Fuzzy control theory. Based on the software of Matlab /Simulink, the comprehensive shift schedule structure was designed and simulated. The simulation results show that the shift point can be regulated automatically by using the comprehensive shift schedules based on the willingness and the actual load. On the premise of meeting the power requirement, the fuel consumption should be minimization, meanwhile it is more convenient to drive in considering the dynamic and fuel economy.
Considering the wide variation range of load when it is running and the convenience of operation for the driver, the coefficient of colligation for the driver was introduced, and a comprehensive shift schedule with the parameters of weight and throttle was proposed based on the traditional dynamic and economic shifting schedules by using Fuzzy control theory. Based on the software of Matlab /Simulink, the comprehensive shift schedule structure was designed and simulated. The simulation results show that the shift point can be regulated automatically by using the comprehensive shift schedules based on the willingness and the actual load. On the premise of meeting the power requirement, the fuel consumption should be minimization, meanwhile it is more convenient to drive in considering the dynamic and fuel economy.
2014, 33(3): 419-422.
Abstract:
Base on the basic principle of vehicle crash analysis using the finite element method, a bus finite element model was built by using Hypermesh software. To simulate the front impact test of the bus, the LS-dyna software is adopted to calculating the deformation of the bus and the acceleration time history curves during the crashing process, the anti-impact capability of the bus is evaluated from these simulations. The results demonstrate that the improvement of local structure can promote the crashworthiness of the bus, but a major change of the vehicle structure is required to have a radical improvement of the crashworthiness of the bus.
Base on the basic principle of vehicle crash analysis using the finite element method, a bus finite element model was built by using Hypermesh software. To simulate the front impact test of the bus, the LS-dyna software is adopted to calculating the deformation of the bus and the acceleration time history curves during the crashing process, the anti-impact capability of the bus is evaluated from these simulations. The results demonstrate that the improvement of local structure can promote the crashworthiness of the bus, but a major change of the vehicle structure is required to have a radical improvement of the crashworthiness of the bus.
2014, 33(3): 423-427.
Abstract:
The finite element model of mechanical elastic wheel, which was similar to the practical one at most, was built. The coordination of structural deformation under pressure was ensured and the function of the restoring spring was realized. The ANSYS software was adopted to calculate the radial stiffness of the wheel. According to the characteristics of structural optimization, Using the length of each wheel rib as the design variables and radial stiffness as optimization objective, the wheel structure was optimized with the sequential quadratic programming (SQP) algorithm. The results showed that the radical stiffness of the wheel was increased effectively within the allowable range.
The finite element model of mechanical elastic wheel, which was similar to the practical one at most, was built. The coordination of structural deformation under pressure was ensured and the function of the restoring spring was realized. The ANSYS software was adopted to calculate the radial stiffness of the wheel. According to the characteristics of structural optimization, Using the length of each wheel rib as the design variables and radial stiffness as optimization objective, the wheel structure was optimized with the sequential quadratic programming (SQP) algorithm. The results showed that the radical stiffness of the wheel was increased effectively within the allowable range.
2014, 33(3): 428-431.
Abstract:
We believe that the Taguchi method is an ideal way to improve the quality of automobile and promote its technological innovation. Considering the application of the Taguchi method to automobile chassis, we analyze the basic principles, usage and the quality /cost evaluation methods of the Taguchi method. The analysis results show that the Taguchi method is simple to use, reproducible and effective and that its application to the automobile industry can help to promote technical innovation, improve the quality of automobile and lower its costs.
We believe that the Taguchi method is an ideal way to improve the quality of automobile and promote its technological innovation. Considering the application of the Taguchi method to automobile chassis, we analyze the basic principles, usage and the quality /cost evaluation methods of the Taguchi method. The analysis results show that the Taguchi method is simple to use, reproducible and effective and that its application to the automobile industry can help to promote technical innovation, improve the quality of automobile and lower its costs.
2014, 33(3): 432-437.
Abstract:
Aiming at the construction principle of vehicle active suspension, this paper established its dynamic model. Considering the time-varying characters of vehicle active suspension state equation, the adaptive LQG active suspension control strategy is proposed, with this daptive control model of vehicle suspension the time-varying parameters and disturbance input parameters can be identified. Combined with LQG control performance index function, the vertical acceleration of sprung mass, weighting coefficients of suspension dynamic flexibility and microstroke of tire are established. The time-varying parameter of suspension is identified by using the extended autoregressive moving average(ARMAX) model, and finally the active suspension adaptive LQG control is achieved. The simulation results show that the adaptive LQG control strategy is better than the LQG control strategy and has improved the ride comfort of vehicle.
Aiming at the construction principle of vehicle active suspension, this paper established its dynamic model. Considering the time-varying characters of vehicle active suspension state equation, the adaptive LQG active suspension control strategy is proposed, with this daptive control model of vehicle suspension the time-varying parameters and disturbance input parameters can be identified. Combined with LQG control performance index function, the vertical acceleration of sprung mass, weighting coefficients of suspension dynamic flexibility and microstroke of tire are established. The time-varying parameter of suspension is identified by using the extended autoregressive moving average(ARMAX) model, and finally the active suspension adaptive LQG control is achieved. The simulation results show that the adaptive LQG control strategy is better than the LQG control strategy and has improved the ride comfort of vehicle.
2014, 33(3): 438-442.
Abstract:
In-situ grown carbon nanofibers reinforced carbon /carbon (CNFs-C /C) composites were prepared by catalyze film-boiling chemical vapor infiltration (FBCVI). After investigating the growing process of CNFs, the influence of catalyst on microstructure and mechanical properties of C /C composites was studied in this paper. The results show that the growth of CNFs at the beginning of deposition was very difficult. As the deposition time increased, the number of CNFs increased sharply. The CNFs were wrapped by PyC matrix after deposition process.The PyC type was ＲL with a great quantity of cone-shaped PyC. The mechanical strength and modulus of CNFs-C / C composites increased by 30.9% and 39.1% respectively, compared to the pure one. The fracture mode of CNWs-C /C composites is pseudo plastic fracture.
In-situ grown carbon nanofibers reinforced carbon /carbon (CNFs-C /C) composites were prepared by catalyze film-boiling chemical vapor infiltration (FBCVI). After investigating the growing process of CNFs, the influence of catalyst on microstructure and mechanical properties of C /C composites was studied in this paper. The results show that the growth of CNFs at the beginning of deposition was very difficult. As the deposition time increased, the number of CNFs increased sharply. The CNFs were wrapped by PyC matrix after deposition process.The PyC type was ＲL with a great quantity of cone-shaped PyC. The mechanical strength and modulus of CNFs-C / C composites increased by 30.9% and 39.1% respectively, compared to the pure one. The fracture mode of CNWs-C /C composites is pseudo plastic fracture.
2014, 33(3): 443-446.
Abstract:
In order to effectively evaluate the structural fatigue reliability of a small subsample, this paper established a projection model for expanding the virtual sample of the S-N curve according to the inter-convertibility between normal distribution and standard normal distribution under the precondition that the logarithmical fatigue life has a normal distribution and the same failure probability. The average error of the projection model for estimating the reliable safety life is within 5% compared with the real experimental results. The F and t test results show that when the significance is 0.05, there is no significant difference between the virtual sample of the projection model and the real test sample. The paper concludes that the virtual sample of the projection model can be used to substitute the real test sample for the statistical analysis of fatigue.
In order to effectively evaluate the structural fatigue reliability of a small subsample, this paper established a projection model for expanding the virtual sample of the S-N curve according to the inter-convertibility between normal distribution and standard normal distribution under the precondition that the logarithmical fatigue life has a normal distribution and the same failure probability. The average error of the projection model for estimating the reliable safety life is within 5% compared with the real experimental results. The F and t test results show that when the significance is 0.05, there is no significant difference between the virtual sample of the projection model and the real test sample. The paper concludes that the virtual sample of the projection model can be used to substitute the real test sample for the statistical analysis of fatigue.
2014, 33(3): 447-451.
Abstract:
The simplified model of the fretting fatigue of dovetail joints between the blade of an aero-engine and its disk was studied. An apparatus for fretting fatigue test was used to characterize the fretting fatigue damage process for titanium alloy TC11 and to observe the crack of the fracture specimen which is initiated in and around the contact zone during the test. The test results show that the number of crack initiation cycles decreases with an increase in the axial force that keeps normal force at a constant value. Also, the influence of the normal force on the crack initiation cycle is not obvious because of the influence of the axial force. In addition, the von Mises equivalent stress and the slip amplitude are the main causes for the reduction of the number of crack initiation cycles.
The simplified model of the fretting fatigue of dovetail joints between the blade of an aero-engine and its disk was studied. An apparatus for fretting fatigue test was used to characterize the fretting fatigue damage process for titanium alloy TC11 and to observe the crack of the fracture specimen which is initiated in and around the contact zone during the test. The test results show that the number of crack initiation cycles decreases with an increase in the axial force that keeps normal force at a constant value. Also, the influence of the normal force on the crack initiation cycle is not obvious because of the influence of the axial force. In addition, the von Mises equivalent stress and the slip amplitude are the main causes for the reduction of the number of crack initiation cycles.
2014, 33(3): 452-459.
Abstract:
SiC single crystal has high hardness and brittleness, therefore being difficult to machine. Its technical parameters in the process of cutting are vitally important for the surface quality, cutting force, and the life of a wire saw when the SiC single crystal wafer is machined. This paper uses the velocity of the wire saw, the feeding velocity of workpiece and its rotational speed as the design factors and designs the three-factor and three-level central composite experiment. The response surface method is used to analyze the test results; the response surface models of the surface roughness of the wafer, cutting force and the life of the wire saw are established respectively, and the cutting parameters such as surface roughness, cutting force and wire saw life optimization are obtained separately. According to the response surface models, the multiple-objective optimization models for surface roughness, cutting force and wire saw life are built respectively to reach equilibrium optimization; the desirability function method is used to obtain their reasonable cutting parameters. The multiple-objective optimization results show that when the surface roughness of the SiC single crystal wafer is 0.6951μm, the cutting force is 2.66515N and the wire saw life is 519.87min utes. Through the multiple-objective optimization, the reasonable cutting parameters are obtained.
SiC single crystal has high hardness and brittleness, therefore being difficult to machine. Its technical parameters in the process of cutting are vitally important for the surface quality, cutting force, and the life of a wire saw when the SiC single crystal wafer is machined. This paper uses the velocity of the wire saw, the feeding velocity of workpiece and its rotational speed as the design factors and designs the three-factor and three-level central composite experiment. The response surface method is used to analyze the test results; the response surface models of the surface roughness of the wafer, cutting force and the life of the wire saw are established respectively, and the cutting parameters such as surface roughness, cutting force and wire saw life optimization are obtained separately. According to the response surface models, the multiple-objective optimization models for surface roughness, cutting force and wire saw life are built respectively to reach equilibrium optimization; the desirability function method is used to obtain their reasonable cutting parameters. The multiple-objective optimization results show that when the surface roughness of the SiC single crystal wafer is 0.6951μm, the cutting force is 2.66515N and the wire saw life is 519.87min utes. Through the multiple-objective optimization, the reasonable cutting parameters are obtained.
2014, 33(3): 460-464.
Abstract:
Cargo barrier net of transport aircraft is designed to arrest the cargo and protect the cabin crew during a survivable crash landing, and it is extremely flexible and develops large displacement under loadings, showing predominately nonlinear behavior and creating convergence problems. This paper presents a modeling technique and analysis strategy for cargo barrier net by the solution 106 module in MSC. Nastran. To investigate the deformed shape and fitting reactions of the barrier net with different initial shape and initial deflection, a cargo barrier net model of transport aircraft was established. Taking into account cargo's diversity of the transport aircraft, three different load cases, uniform distributed load and concentrated load and uniform concentrated combination, were analyzed and simulated.
Cargo barrier net of transport aircraft is designed to arrest the cargo and protect the cabin crew during a survivable crash landing, and it is extremely flexible and develops large displacement under loadings, showing predominately nonlinear behavior and creating convergence problems. This paper presents a modeling technique and analysis strategy for cargo barrier net by the solution 106 module in MSC. Nastran. To investigate the deformed shape and fitting reactions of the barrier net with different initial shape and initial deflection, a cargo barrier net model of transport aircraft was established. Taking into account cargo's diversity of the transport aircraft, three different load cases, uniform distributed load and concentrated load and uniform concentrated combination, were analyzed and simulated.
2014, 33(3): 465-468.
Abstract:
Currently, an aircraft's pre-assembled panel needs to be repositioned on automatic drilling and riveting machines, thus reducing the assembly efficiency. Through analyzing the flexible assembly technology and combining the structural characteristics of the pre-assembled panel with automatic drilling and riveting machines, we use the genetic algorithm to optimize and design a pre-assembled flexible positioning device for a certain type of aircraft panel. This device can be implemented on flexible pre-assembly for several aircraft panels and can be well combined with automatic drilling and riveting machines. It can avoid the repositioning of aircraft panel on automatic drilling and riveting machines to enhance assembly efficiency.
Currently, an aircraft's pre-assembled panel needs to be repositioned on automatic drilling and riveting machines, thus reducing the assembly efficiency. Through analyzing the flexible assembly technology and combining the structural characteristics of the pre-assembled panel with automatic drilling and riveting machines, we use the genetic algorithm to optimize and design a pre-assembled flexible positioning device for a certain type of aircraft panel. This device can be implemented on flexible pre-assembly for several aircraft panels and can be well combined with automatic drilling and riveting machines. It can avoid the repositioning of aircraft panel on automatic drilling and riveting machines to enhance assembly efficiency.
