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RSS2012 Vol. 31, No. 12
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2012, 31(12): 1894-1897.
PDF 2418KB
Abstract:
Cruise performance is the design point in civil aircraft wing design.The wing's aerodynamic characteristics changes due to its static deformation because of the aircraft static aeroelastic effects when it is in cruise condition.It is important to do research on wing jig-shape design to make the aircraft's cruise performance meet its design criterion.A fast approach to the wing jig-shape aeroelastic design problem was presented in this paper.At first,aerodynamic correction factor techniques was applied to doublet-lattice method and acquired a good computational efficiency for improving the accuracy of aerodynamic force.The initial jig-shape of the wing was obtained through a fully decoupled method,and the designed jig-shape was got by coupling iterative calculation.This approach not only convergences fast,but also gets results with high accuracy.
Cruise performance is the design point in civil aircraft wing design.The wing's aerodynamic characteristics changes due to its static deformation because of the aircraft static aeroelastic effects when it is in cruise condition.It is important to do research on wing jig-shape design to make the aircraft's cruise performance meet its design criterion.A fast approach to the wing jig-shape aeroelastic design problem was presented in this paper.At first,aerodynamic correction factor techniques was applied to doublet-lattice method and acquired a good computational efficiency for improving the accuracy of aerodynamic force.The initial jig-shape of the wing was obtained through a fully decoupled method,and the designed jig-shape was got by coupling iterative calculation.This approach not only convergences fast,but also gets results with high accuracy.
2012, 31(12): 1898-1903.
Abstract:
To improve the flexibility of foot and self-adaptive capacity in shape changes,variable cross section beam was proposed to simulate the compliant foot of hopping kangaroo.To establish the kinetic equation of the stance stage of kangaroo hopping robot,Hamilton's principle together with finite element method was adopted.The changes of elastic potential energy and trajectory of ankle joint in certain example were analyzed by means of Matlab.Through ANSYS and ADAMS,the dynamic modelling and the motion simulation of kangaroo hopping robot were conducted to gain the variation of ground reaction force and the stiffness characteristic of compliant foot.A experimental platform used to contrast flexible wedge foot and flexible curve foot was set up to measure the acceleration curve in the stance stage.The results indicate that flexible curve foot has the capability to dissipate and store part of the landing impact energy,through which the impact can be eased and the performance of take-off can be improved.
To improve the flexibility of foot and self-adaptive capacity in shape changes,variable cross section beam was proposed to simulate the compliant foot of hopping kangaroo.To establish the kinetic equation of the stance stage of kangaroo hopping robot,Hamilton's principle together with finite element method was adopted.The changes of elastic potential energy and trajectory of ankle joint in certain example were analyzed by means of Matlab.Through ANSYS and ADAMS,the dynamic modelling and the motion simulation of kangaroo hopping robot were conducted to gain the variation of ground reaction force and the stiffness characteristic of compliant foot.A experimental platform used to contrast flexible wedge foot and flexible curve foot was set up to measure the acceleration curve in the stance stage.The results indicate that flexible curve foot has the capability to dissipate and store part of the landing impact energy,through which the impact can be eased and the performance of take-off can be improved.
2012, 31(12): 1904-1909.
Abstract:
Taking a car as research object,the Adams/car Software was adopted to build vehicle virtual prototype model.Combined with the virtual prototype model,Taguchi robust optimum design method was applied to the design of smoothness optimization to improve vehicle ride comfort.With the methodology,only a small number of tests and simple analysis are needed to get reliable results,which can effectively minimize the influence of uncontrollable factors on vhicle ride comfort.Compared with traditional optimum design method,Taguchi robust optimum design method has advantages in producing more realistic results and stronger anti-interference ability.
Taking a car as research object,the Adams/car Software was adopted to build vehicle virtual prototype model.Combined with the virtual prototype model,Taguchi robust optimum design method was applied to the design of smoothness optimization to improve vehicle ride comfort.With the methodology,only a small number of tests and simple analysis are needed to get reliable results,which can effectively minimize the influence of uncontrollable factors on vhicle ride comfort.Compared with traditional optimum design method,Taguchi robust optimum design method has advantages in producing more realistic results and stronger anti-interference ability.
2012, 31(12): 1910-1915.
Abstract:
In view of the problems existed in current enterprise process execution,such as lack of enforcement,backward of monitoring means and lag with on-site feedback,etc.,a project of process online execution system was presented.By researching on the key technology,such as the paperless browsing technology about process data based on XML(extensible markup language,XML) and XSL(extensible stylesheet language,XSL),the production process control and data collection based on RFID technology and temporary process modification based on system integration,the process control of process execution was strengthened.The prompt feedback of site information to related department was realized and the engineering scrap and quality accident caused by human error was avoided.
In view of the problems existed in current enterprise process execution,such as lack of enforcement,backward of monitoring means and lag with on-site feedback,etc.,a project of process online execution system was presented.By researching on the key technology,such as the paperless browsing technology about process data based on XML(extensible markup language,XML) and XSL(extensible stylesheet language,XSL),the production process control and data collection based on RFID technology and temporary process modification based on system integration,the process control of process execution was strengthened.The prompt feedback of site information to related department was realized and the engineering scrap and quality accident caused by human error was avoided.
2012, 31(12): 1916-1920.
Abstract:
In order to analyze the handling characteristics of a certain formula racing car by virtual dynamics test,by applying the mechanical system simulation software ADAMS,the model of a formula racing car was established with aerodynamic characteristics taken into consideration.By comparing with the experiment date of steering wheel angle step input,the correctness of the virtual prototyping model was verified.Based on these,the handling stability virtual tests such as steering wheel angle step input,steady static circular and steering efforts were performed.The simulation results show that the racing car has rapid transient response and moderate tendency to understeer at various speed,good steer handiness and returnability which provides strong basis for the performance prediction.
In order to analyze the handling characteristics of a certain formula racing car by virtual dynamics test,by applying the mechanical system simulation software ADAMS,the model of a formula racing car was established with aerodynamic characteristics taken into consideration.By comparing with the experiment date of steering wheel angle step input,the correctness of the virtual prototyping model was verified.Based on these,the handling stability virtual tests such as steering wheel angle step input,steady static circular and steering efforts were performed.The simulation results show that the racing car has rapid transient response and moderate tendency to understeer at various speed,good steer handiness and returnability which provides strong basis for the performance prediction.
2012, 31(12): 1921-1926.
Abstract:
The influence of shot peening intensity,and surface integrity on fatigue properties of TC21 titanium alloy was studied to improve fatigue resistance of the high strength titanium alloy.The influence of shot peening on surface residual stress,surface roughness,surface morphology and surface hardness was studied by using X-ray diffraction analysis,surface profile measurement,scanning electron microscopy and microhardness instrument,etc.The mechanism of fatigue resistance improved by shot peening was also discussed.The results reveal that the effect of fatigue properties can be obviously improved by optimized shot peening process.But the fatigue properties is not a simple monotonic variation with shot peening intensity.The surface integrity and fatigue resistance are the most optimum in a certain shot peening parameters,while they will be decreased by exorbitant shot peening intensity.Therefore,when choosing shot peening parameters,it is blinded to merely pursue exorbitant intensity and ignore the surface integrity of metal materials.
The influence of shot peening intensity,and surface integrity on fatigue properties of TC21 titanium alloy was studied to improve fatigue resistance of the high strength titanium alloy.The influence of shot peening on surface residual stress,surface roughness,surface morphology and surface hardness was studied by using X-ray diffraction analysis,surface profile measurement,scanning electron microscopy and microhardness instrument,etc.The mechanism of fatigue resistance improved by shot peening was also discussed.The results reveal that the effect of fatigue properties can be obviously improved by optimized shot peening process.But the fatigue properties is not a simple monotonic variation with shot peening intensity.The surface integrity and fatigue resistance are the most optimum in a certain shot peening parameters,while they will be decreased by exorbitant shot peening intensity.Therefore,when choosing shot peening parameters,it is blinded to merely pursue exorbitant intensity and ignore the surface integrity of metal materials.
2012, 31(12): 1927-1932.
Abstract:
In the process of eco-design there are conflicts between environmental elements and technical measures that is hard to identify and solve.This article proposed a rapid product eco-design model integrating CBR,TOC and TRIZ,reusing the past design experience to solve the above problems.The first step reused the successful case from the database to accelerate the design process based on the similarity calculation.Combining seven eco-design targets from WBCSD,conflicts were identified with CRT and CRD analysis and solved by TRIZ tools;product eco-design was formed afterwards.The model was applied to the eco-design of power outlet and proved to be feasible and effective.
In the process of eco-design there are conflicts between environmental elements and technical measures that is hard to identify and solve.This article proposed a rapid product eco-design model integrating CBR,TOC and TRIZ,reusing the past design experience to solve the above problems.The first step reused the successful case from the database to accelerate the design process based on the similarity calculation.Combining seven eco-design targets from WBCSD,conflicts were identified with CRT and CRD analysis and solved by TRIZ tools;product eco-design was formed afterwards.The model was applied to the eco-design of power outlet and proved to be feasible and effective.
2012, 31(12): 1933-1937.
Abstract:
A new approach was presented for the five-axis NC machining of the ruled surfaces slot with surface of revolution part.The cutter axis orientation and the cutter location point were identified though the ruled surface driving method in rough machining,and the calculation method was researched.The double points offset method was used to modify the error caused by flanking milling intractable ruled surface by cylindrical cutter.A cutter location point correction algorithm was presented to solve the problem of overcut in flat-end tool machining.Experimental results demonstrate that the proposed method not only solves the problem of machining principle error in flanking milling intractable ruled surface by cylindrical cutter,but also improves machined surface quality and reduces surface roughness and improves the quality of test piece reliably.
A new approach was presented for the five-axis NC machining of the ruled surfaces slot with surface of revolution part.The cutter axis orientation and the cutter location point were identified though the ruled surface driving method in rough machining,and the calculation method was researched.The double points offset method was used to modify the error caused by flanking milling intractable ruled surface by cylindrical cutter.A cutter location point correction algorithm was presented to solve the problem of overcut in flat-end tool machining.Experimental results demonstrate that the proposed method not only solves the problem of machining principle error in flanking milling intractable ruled surface by cylindrical cutter,but also improves machined surface quality and reduces surface roughness and improves the quality of test piece reliably.
2012, 31(12): 1938-1943.
Abstract:
In order to effectively control the intergranular corrosion(IGC) failure behavior of 2E12 aluminium alloy,the influence of shot peening(SP) and stress factor on the IGC behaviour of the alloy were investigated by means of immersion corrosion experiment,metallographic analysis,scanning electron microscopy(SEM) and X-ray diffraction analysis,etc.The results show that 2E12-T3 alloy is very sensitive to IGC.Tensile stress can increase IGC sensitivity,while compressive stress can decrease IGC sensitivity.The IGC sensitivity of 2E12-T3 alloy can be effectively decreased by proper shot peeing treatment(shot peening intensity is 0.15 mmN,coverage is 100%).The electrochemical activity is low and selective corrosion in grain boundary is effectively controlled by SP with suitable distribution of residual compressive stress and refinement of grain in surface layer.However,the IGC sensitivity of 2E12-T3 alloy will increase when shot peeing intensity is too high or its coverage is too large because such serious damage as delamination may occur in the SP surface layer of the alloy.
In order to effectively control the intergranular corrosion(IGC) failure behavior of 2E12 aluminium alloy,the influence of shot peening(SP) and stress factor on the IGC behaviour of the alloy were investigated by means of immersion corrosion experiment,metallographic analysis,scanning electron microscopy(SEM) and X-ray diffraction analysis,etc.The results show that 2E12-T3 alloy is very sensitive to IGC.Tensile stress can increase IGC sensitivity,while compressive stress can decrease IGC sensitivity.The IGC sensitivity of 2E12-T3 alloy can be effectively decreased by proper shot peeing treatment(shot peening intensity is 0.15 mmN,coverage is 100%).The electrochemical activity is low and selective corrosion in grain boundary is effectively controlled by SP with suitable distribution of residual compressive stress and refinement of grain in surface layer.However,the IGC sensitivity of 2E12-T3 alloy will increase when shot peeing intensity is too high or its coverage is too large because such serious damage as delamination may occur in the SP surface layer of the alloy.
2012, 31(12): 1944-1948.
Abstract:
Health management is an effective way to assure the flight safety and economy.Aiming at the uncertainty of health management strategies,firstly we analyzed the uncertainty sources of the monitoring system based on the principle of monitoring approaches.Then the uncertainty factors in the signal detection and processing and threshold confirmation were explored and the uncertainty factors from the model used for life predication and maintenance strategy-making were analyzed.Finally,the corresponding tactics for reducing uncertainty in every stage were proposed in the paper,which provide useful references for designing prognostics and health management capacity of aircrafts.
Health management is an effective way to assure the flight safety and economy.Aiming at the uncertainty of health management strategies,firstly we analyzed the uncertainty sources of the monitoring system based on the principle of monitoring approaches.Then the uncertainty factors in the signal detection and processing and threshold confirmation were explored and the uncertainty factors from the model used for life predication and maintenance strategy-making were analyzed.Finally,the corresponding tactics for reducing uncertainty in every stage were proposed in the paper,which provide useful references for designing prognostics and health management capacity of aircrafts.
2012, 31(12): 1949-1954.
Abstract:
It was successful that extended finite element method(XFEM) was theoretically applied to the strong discontinuity problems such as cracks so that the development and application of the method are being increased rapidly.However,in practical applications,there are still many technical issues such as the mesh density to be studied.In order to verify and improve the effectiveness of XFEM on the calculation of crack stress intensity factor,the corresponding formula of XFEM with four-node isoparametric element was derived and a complete Matlab code was also edited aiming at calculating the crack tip stress intensity factor of a plate with crack.Based upon the program,the crack tip stress intensity factors for a typical plate with crack were calculated and the results by XFEM were compared with those by the traditional finite element method(FEM).The effect of the mesh parameters on the XFEM results was further studied.The study shows that XFEM has a very good accuracy in the calculation of crack tip stress intensity factor,but the results by XFEM are sensitive to the density of the mesh,this should be paid more attention to practical applications.
It was successful that extended finite element method(XFEM) was theoretically applied to the strong discontinuity problems such as cracks so that the development and application of the method are being increased rapidly.However,in practical applications,there are still many technical issues such as the mesh density to be studied.In order to verify and improve the effectiveness of XFEM on the calculation of crack stress intensity factor,the corresponding formula of XFEM with four-node isoparametric element was derived and a complete Matlab code was also edited aiming at calculating the crack tip stress intensity factor of a plate with crack.Based upon the program,the crack tip stress intensity factors for a typical plate with crack were calculated and the results by XFEM were compared with those by the traditional finite element method(FEM).The effect of the mesh parameters on the XFEM results was further studied.The study shows that XFEM has a very good accuracy in the calculation of crack tip stress intensity factor,but the results by XFEM are sensitive to the density of the mesh,this should be paid more attention to practical applications.
2012, 31(12): 1955-1958.
Abstract:
This paper presents a novel method for fabrication of polymethyl methacrylate(PMMA) microlens array by contactless hot-embossing with through-holes stainless molds.An array of plano convex microlenses was formed due to the surface tension of polymer above the glass transition temperature.The curvature and height was controlled by adjusting the temperature,pressure and time duration.In addition,the principle of contactless hot-embossing by finite element analysis was studied,and the model was built by Ansys.An independently developed hot-embossing equipment was used to fabricate microlens arrays on PMMA sheet.And the influences of technological parameters such as temperature and pressure were analyzed.Finally,their optical performances were tested.The experimental results show that microlens array has good surface features and high position precision.The contactless hot-embossing technology is process simplified,one-step forming,independent on surface quality of mold.
This paper presents a novel method for fabrication of polymethyl methacrylate(PMMA) microlens array by contactless hot-embossing with through-holes stainless molds.An array of plano convex microlenses was formed due to the surface tension of polymer above the glass transition temperature.The curvature and height was controlled by adjusting the temperature,pressure and time duration.In addition,the principle of contactless hot-embossing by finite element analysis was studied,and the model was built by Ansys.An independently developed hot-embossing equipment was used to fabricate microlens arrays on PMMA sheet.And the influences of technological parameters such as temperature and pressure were analyzed.Finally,their optical performances were tested.The experimental results show that microlens array has good surface features and high position precision.The contactless hot-embossing technology is process simplified,one-step forming,independent on surface quality of mold.
2012, 31(12): 1959-1962.
Abstract:
Considering the randomness of geometrical dimensions,material properties and applied loads of crawler crane's boom system,the reliability analysis model of compressive-bending member's stability was established based on Response Surface Method(RSM),which involves response surface functions replacing performance functions and first order second moment(FOSM) method.The model was used to calculate the reliability of compressive-bending members of a certain existing crawler crane's boom.The results indicate that the relationship between the reliability of compressive-bending member's buckling and applied loads takes on nonlinear tendency,reflecting the law of reliability varying with loads.
Considering the randomness of geometrical dimensions,material properties and applied loads of crawler crane's boom system,the reliability analysis model of compressive-bending member's stability was established based on Response Surface Method(RSM),which involves response surface functions replacing performance functions and first order second moment(FOSM) method.The model was used to calculate the reliability of compressive-bending members of a certain existing crawler crane's boom.The results indicate that the relationship between the reliability of compressive-bending member's buckling and applied loads takes on nonlinear tendency,reflecting the law of reliability varying with loads.
2012, 31(12): 1963-1966.
Abstract:
A kind of pulldown armed truck crane was studied in this paper.The virtual prototype model of that was built by ADAMS(Automatic Dynamic Analysis of Mechanical Systems)software and the kinematic simulation of its ratation was done.The centroid curve of the pulldown armed truck crane was obtained.Based on this,the stability of the crane system was analyzed on the theory of trimming moment and the maximum lifting weights on diffenert danger paragraph were drawn by Matlab(Matrix Laboratory) software.The result indicates that the maximum lifting weight on frontage and left-frontage is less than the rated value of the truck crane,which are the dangerous places to overturn.Compared with traditional method,the ADAMS method in this paper can satisfy the design need of efficient,flexible design.
A kind of pulldown armed truck crane was studied in this paper.The virtual prototype model of that was built by ADAMS(Automatic Dynamic Analysis of Mechanical Systems)software and the kinematic simulation of its ratation was done.The centroid curve of the pulldown armed truck crane was obtained.Based on this,the stability of the crane system was analyzed on the theory of trimming moment and the maximum lifting weights on diffenert danger paragraph were drawn by Matlab(Matrix Laboratory) software.The result indicates that the maximum lifting weight on frontage and left-frontage is less than the rated value of the truck crane,which are the dangerous places to overturn.Compared with traditional method,the ADAMS method in this paper can satisfy the design need of efficient,flexible design.
2012, 31(12): 1967-1973.
Abstract:
Strain range partitioning(SRP) is a method developed by Manson and his colleagues during the early 1970s for creep-fatigue life prediction.Through years of research and development,SRP method have become one of the few methods gained engineering application,and is extended to thermomechanical fatigue life prediction.To promote further research and application of SRP and the derivative methods in China,the development and application status of the SRP method was reviewed and summarized in this paper.The basic idea and formulating processes of the total strain version of strain range partitioning(TS-SRP) were introduced and explained in detail.Finally,the basic equations,material parameters and their correlations were summarized.
Strain range partitioning(SRP) is a method developed by Manson and his colleagues during the early 1970s for creep-fatigue life prediction.Through years of research and development,SRP method have become one of the few methods gained engineering application,and is extended to thermomechanical fatigue life prediction.To promote further research and application of SRP and the derivative methods in China,the development and application status of the SRP method was reviewed and summarized in this paper.The basic idea and formulating processes of the total strain version of strain range partitioning(TS-SRP) were introduced and explained in detail.Finally,the basic equations,material parameters and their correlations were summarized.
2012, 31(12): 1974-1979.
Abstract:
In view of the needs of EPS material processing market and forming equipments status at present,an EPS rapid prototyping system based on single chip microcomputer inferior machine was developed.The system's overall design scheme was determined,the structure and function of whose main modules,including mechanical part,electrical part and PC software,were introduced.Underlying development of electrical system was completed to achieve stepper motor drivers and electric wire temperature control.Finally,software functions were tested and a real foam part was cut using the system.It proved that the system is easy to use and dimension tolerance is small which can satisfy the engineering requirement.
In view of the needs of EPS material processing market and forming equipments status at present,an EPS rapid prototyping system based on single chip microcomputer inferior machine was developed.The system's overall design scheme was determined,the structure and function of whose main modules,including mechanical part,electrical part and PC software,were introduced.Underlying development of electrical system was completed to achieve stepper motor drivers and electric wire temperature control.Finally,software functions were tested and a real foam part was cut using the system.It proved that the system is easy to use and dimension tolerance is small which can satisfy the engineering requirement.
2012, 31(12): 1980-1987.
Abstract:
To obtain the effects of airfoil geometry on Radar Cross Section(RCS),the RCS characteristics of a series of reflex airfoils were investigated using the method of moment(MOM) with high accuracy.These airfoils are usually used in the design of blended-wing-body(BWB) airframe and are modeled by the parametric method.The MOM is validated on the NACA0012.The bistatic RCS of NACA0012 agrees well with the data of references.An effective factor was defined to qualify the effects of geometric parameters on the RCS.Meanwhile,the effects of geometric parameters on aerodynamic characteristics were also considered.Based on the effective factor analysis using table values,the geometric parameters were divided into three categories in the RCS design.
To obtain the effects of airfoil geometry on Radar Cross Section(RCS),the RCS characteristics of a series of reflex airfoils were investigated using the method of moment(MOM) with high accuracy.These airfoils are usually used in the design of blended-wing-body(BWB) airframe and are modeled by the parametric method.The MOM is validated on the NACA0012.The bistatic RCS of NACA0012 agrees well with the data of references.An effective factor was defined to qualify the effects of geometric parameters on the RCS.Meanwhile,the effects of geometric parameters on aerodynamic characteristics were also considered.Based on the effective factor analysis using table values,the geometric parameters were divided into three categories in the RCS design.
2012, 31(12): 1988-1992.
Abstract:
The mechanical structure composition of general seat belt-pretensioner and its pretension process were analyzed.In connection with its own shortcomings,the control system of intelligent seat belt-pretensioner was proposed.Early warning subsystems of distance,vehicle crosswind stability,vehicle longitudinal stability and crash were built,and the system control parameters were also set.With the control software of intelligent seat belt-pretensioner,four input signals of vehicle instability were set for experiment,including relative time distance from ahead-vehicle,vehicle yaw rate,steering wheel angle and vehicle deceleration.The test results show that intelligent seat belt's pretention length can be controlled within 0～10 cm;pretention force can be controlled within 0～20 N,and the maximum reaction time is 19 ms.The intelligent seat belt-pretensioner plays an important role in early warning and tightening,in order to effectively protect the drivers and passengers.
The mechanical structure composition of general seat belt-pretensioner and its pretension process were analyzed.In connection with its own shortcomings,the control system of intelligent seat belt-pretensioner was proposed.Early warning subsystems of distance,vehicle crosswind stability,vehicle longitudinal stability and crash were built,and the system control parameters were also set.With the control software of intelligent seat belt-pretensioner,four input signals of vehicle instability were set for experiment,including relative time distance from ahead-vehicle,vehicle yaw rate,steering wheel angle and vehicle deceleration.The test results show that intelligent seat belt's pretention length can be controlled within 0～10 cm;pretention force can be controlled within 0～20 N,and the maximum reaction time is 19 ms.The intelligent seat belt-pretensioner plays an important role in early warning and tightening,in order to effectively protect the drivers and passengers.
2012, 31(12): 1993-1996.
Abstract:
Some final path decision may not be reasonable during an intelligent vehicle avoiding obstacle,therefore,a decision making system for path decision based on tentacle algorithm of obstacle avoidance of intelligent vehicle was presented.The final path decision based on this method is much better.Firstly,we builded a obstacle map.Then,we described the tentacle algorithm and showed a group of tentacle.Finally,the calculation of drivable area and the institution of the decision system which includes three variables were described.The results show that the three variables make the vehicle driving along the expected trajectory,which proves that the decision system is reliable and effective.
Some final path decision may not be reasonable during an intelligent vehicle avoiding obstacle,therefore,a decision making system for path decision based on tentacle algorithm of obstacle avoidance of intelligent vehicle was presented.The final path decision based on this method is much better.Firstly,we builded a obstacle map.Then,we described the tentacle algorithm and showed a group of tentacle.Finally,the calculation of drivable area and the institution of the decision system which includes three variables were described.The results show that the three variables make the vehicle driving along the expected trajectory,which proves that the decision system is reliable and effective.
2012, 31(12): 1997-2002.
Abstract:
Experimental study was performed in the pursuit of fatigue behavior and residual strength of composite-to-titanium single lap joints multi fastener to verify its safety.The influences of bolt diameters and clearances were taken into account.Via the approach of hole elongation tracking,acoustic emission,ultra-sonic and C-scan,the experimental results indicate no failure and no load distribution change throughout 60 000 cycles under the assigned fatigue load,which guarantes the safety of the joint;various bolt diameters and clearances have trivial influence on the fatigue performance and load distribution during the fatigue process.The residual strength of the joint shows a inclining trend with the increase of the bolt diameters,while is affected little by the bolt clearances.
Experimental study was performed in the pursuit of fatigue behavior and residual strength of composite-to-titanium single lap joints multi fastener to verify its safety.The influences of bolt diameters and clearances were taken into account.Via the approach of hole elongation tracking,acoustic emission,ultra-sonic and C-scan,the experimental results indicate no failure and no load distribution change throughout 60 000 cycles under the assigned fatigue load,which guarantes the safety of the joint;various bolt diameters and clearances have trivial influence on the fatigue performance and load distribution during the fatigue process.The residual strength of the joint shows a inclining trend with the increase of the bolt diameters,while is affected little by the bolt clearances.
2012, 31(12): 2003-2009.
Abstract:
Mathematical characterization of changes in tire radial properties when tire blow-out was made by simplifying tire to be a series spring system.Combining the changes in shear mechanical properties of tire,a 14-DOF whole vehicle model was established using Simulink/Matlab.Under straight and curve drive condition at 100 km/h,lateral acceleration,yaw acceleration and roll angle of a vehicle with blown-out tire were simulated by the proposed model and the Carsim model.Results of the two models show a good agreement.The proposed model provides a relatively comprehensive mathematical characterization for tire blow-out course and a basic frame for modeling of vehicle with blown-out tire.Based on work in this paper,further analysis in model expansion,vehicle dynamics after tire blow-out and stability control can be carried out.
Mathematical characterization of changes in tire radial properties when tire blow-out was made by simplifying tire to be a series spring system.Combining the changes in shear mechanical properties of tire,a 14-DOF whole vehicle model was established using Simulink/Matlab.Under straight and curve drive condition at 100 km/h,lateral acceleration,yaw acceleration and roll angle of a vehicle with blown-out tire were simulated by the proposed model and the Carsim model.Results of the two models show a good agreement.The proposed model provides a relatively comprehensive mathematical characterization for tire blow-out course and a basic frame for modeling of vehicle with blown-out tire.Based on work in this paper,further analysis in model expansion,vehicle dynamics after tire blow-out and stability control can be carried out.
2012, 31(12): 2010-2013.
Abstract:
In order to improve the computational efficiency of genetic algorithm(GA) and avoid getting a local optimum solution in complex method(CM),these two methods were combined together using their advantages to form a hybrid optimization method based on the best vertex(GACM) in this investigation.In this method,GA was used to get an approximate global optimum solution in design space.Then this solution was taken as the initial vertex of CM to search for a final solution.GA,CM and the hybrid method have been used in the aerodynamic optimization design of RAE2822 airfoil.The results show that the hybrid method is more efficient and can converge to global optimum solution better.
In order to improve the computational efficiency of genetic algorithm(GA) and avoid getting a local optimum solution in complex method(CM),these two methods were combined together using their advantages to form a hybrid optimization method based on the best vertex(GACM) in this investigation.In this method,GA was used to get an approximate global optimum solution in design space.Then this solution was taken as the initial vertex of CM to search for a final solution.GA,CM and the hybrid method have been used in the aerodynamic optimization design of RAE2822 airfoil.The results show that the hybrid method is more efficient and can converge to global optimum solution better.
2012, 31(12): 2014-2018.
Abstract:
According to the difficult test processing of ozonizer in fault condition at present,a sort of ozonizer fault diagnosis was designed in this paper.Fault feature extraction was got by current transformer when ozonizer in fault conditions such as spark-over,breakdown and water influx.Fault diagnosis judge criteria was worked out through the choice of appropriate membership functions to establish fuzzy set which is based on analyzing and processing experimental data for each fault state.So the system can monitor the working state of ozonizer in real-time according to this diagnostic criteria.And over-current protection units were designed for preventing over-current in ozone generating main circuit,while ozonizer in fault condition.So unrecoverable damage was avoided by monitoring the magnitude of current in main circuit in real-time by shutting down the power switch through synchronized signal generated by D flip-flop in over-current state.The experimental results show that this system can diagnose ozonizer fault in real-time accurately and the main circuit would not be damaged by over-current in long time working condition.
According to the difficult test processing of ozonizer in fault condition at present,a sort of ozonizer fault diagnosis was designed in this paper.Fault feature extraction was got by current transformer when ozonizer in fault conditions such as spark-over,breakdown and water influx.Fault diagnosis judge criteria was worked out through the choice of appropriate membership functions to establish fuzzy set which is based on analyzing and processing experimental data for each fault state.So the system can monitor the working state of ozonizer in real-time according to this diagnostic criteria.And over-current protection units were designed for preventing over-current in ozone generating main circuit,while ozonizer in fault condition.So unrecoverable damage was avoided by monitoring the magnitude of current in main circuit in real-time by shutting down the power switch through synchronized signal generated by D flip-flop in over-current state.The experimental results show that this system can diagnose ozonizer fault in real-time accurately and the main circuit would not be damaged by over-current in long time working condition.
2012, 31(12): 2019-2022.
Abstract:
Strength of adhesive bonding repair composite material laminated with different path parameters were tested on MTS material test machine.Strains during the test were recorded using five strain foils bonded on different positions of the laminate.The result indicates that: 1) the patch changes the strain distribution and increases the strength of the laminates;2) the optimized repairing efficiency can be obtained when the ply-up angle of the patch is 0 or 90°,the size of the patch is 2～3 times of the damaged size and the thickness of the patch is 0.6～1 time of the damage deepness.
Strength of adhesive bonding repair composite material laminated with different path parameters were tested on MTS material test machine.Strains during the test were recorded using five strain foils bonded on different positions of the laminate.The result indicates that: 1) the patch changes the strain distribution and increases the strength of the laminates;2) the optimized repairing efficiency can be obtained when the ply-up angle of the patch is 0 or 90°,the size of the patch is 2～3 times of the damaged size and the thickness of the patch is 0.6～1 time of the damage deepness.
2012, 31(12): 2023-2027.
Abstract:
Machining accuracy of cross-legged parallel machine tool of zero drive force was investigated.Dynamic equation of a cross-legged parallel machine tool was obtained by Newton-Euler approach.Drive force of a leg was solved by the dynamic equation.The effects of clearance between a screw and a nut on machining accuracy were analyzed.The results show that if there is clearance between a screw and a nut,machining accuracy of a cross-legged parallel machine tool will be affected near the zero drive force posotion of a cross-legged parallel machine tool.Machining accuracy of a cross-legged parallel machine tool is not affected by a preload screw nut,but power consumption and wear of screw pair is increased.A preload mechanism of a screw nut is redundant in a cross-legged parallel machine tool which often works under non-zero drive force condition.It was expected that machining time of a cycle process is controlled in order that a cross-legged parallel machine tool does not have the position of zero drive force.A preload mechanism of a screw nut was set and used according to critical machining time.
Machining accuracy of cross-legged parallel machine tool of zero drive force was investigated.Dynamic equation of a cross-legged parallel machine tool was obtained by Newton-Euler approach.Drive force of a leg was solved by the dynamic equation.The effects of clearance between a screw and a nut on machining accuracy were analyzed.The results show that if there is clearance between a screw and a nut,machining accuracy of a cross-legged parallel machine tool will be affected near the zero drive force posotion of a cross-legged parallel machine tool.Machining accuracy of a cross-legged parallel machine tool is not affected by a preload screw nut,but power consumption and wear of screw pair is increased.A preload mechanism of a screw nut is redundant in a cross-legged parallel machine tool which often works under non-zero drive force condition.It was expected that machining time of a cycle process is controlled in order that a cross-legged parallel machine tool does not have the position of zero drive force.A preload mechanism of a screw nut was set and used according to critical machining time.
2012, 31(12): 2028-2033.
Abstract:
In order to design the product color that meets consumers' affective needs,product color design method based on fuzzy analytic hierarchy process(FAHP) was proposed.Firstly,factor analysis was utilized to determine the kansei images of products,and the colors of product components were analyzed.Based on this,experimental samples were made.Secondly,the FAHP model of the optimum color design was constructed.Fuzzy judgement matrix was built through investigation,and the subjective weights among kansei images were set according to customers' needs.Finally,the scores of alternatives were calculated and defuzzified.They were ranked through mean and standard deviation,and then the optimum color design was ascertained.An experimental study of mobile phone color design was conducted based on the presented method,and the results shown that this method is valid and feasible.
In order to design the product color that meets consumers' affective needs,product color design method based on fuzzy analytic hierarchy process(FAHP) was proposed.Firstly,factor analysis was utilized to determine the kansei images of products,and the colors of product components were analyzed.Based on this,experimental samples were made.Secondly,the FAHP model of the optimum color design was constructed.Fuzzy judgement matrix was built through investigation,and the subjective weights among kansei images were set according to customers' needs.Finally,the scores of alternatives were calculated and defuzzified.They were ranked through mean and standard deviation,and then the optimum color design was ascertained.An experimental study of mobile phone color design was conducted based on the presented method,and the results shown that this method is valid and feasible.
2012, 31(12): 2034-2038.
Abstract:
As it is difficult to control the effective forging time of the liquid-air hammer,its dynamics characteristic of the work process was researched,and the sub-time control method was proposed.The liquid-air hammer work process was divided into four continuous stages: drop hammer,hit,bounce and return.For analysis and solving the effective time range of four stages,the dynamic models and differential equations of different stages were established according to the hammer's works.Meanwhile differential equations were solved by Matlab.And samples of four effective time ranges were established on different hit heights and energy.The control system of liquid-air hammer,combined with effective time samples,was redesigned on the Programmable Logic Controller(PLC) and applied to production.The practice proves that this method is feasible for the simplification of some part of mechanical structure of the hammer,and improves operational safety.By more than 5 000 times forging,the system didn't appear any breakdown.
As it is difficult to control the effective forging time of the liquid-air hammer,its dynamics characteristic of the work process was researched,and the sub-time control method was proposed.The liquid-air hammer work process was divided into four continuous stages: drop hammer,hit,bounce and return.For analysis and solving the effective time range of four stages,the dynamic models and differential equations of different stages were established according to the hammer's works.Meanwhile differential equations were solved by Matlab.And samples of four effective time ranges were established on different hit heights and energy.The control system of liquid-air hammer,combined with effective time samples,was redesigned on the Programmable Logic Controller(PLC) and applied to production.The practice proves that this method is feasible for the simplification of some part of mechanical structure of the hammer,and improves operational safety.By more than 5 000 times forging,the system didn't appear any breakdown.
2012, 31(12): 2039-2043.
Abstract:
Spring safety device as the roll crusher's key component,the value of spring stiffness has a very important impact on the performance of the whole device,when the spring-loaded is too large,the wear is intensified and the power consumption is increased;while small spring force will increase the number of articles whose dimeter are bigger than the averige value.Aiming at this problem,the relationship between different stiffness of spring and the vibration of angular velocity of the moving roll and its moving distance were studied through simulation analysis based on the ADAMS softwear by setting five different spring stiffness.To simulate the working condition of the crusher,random signal was applied.The simulation results show that the relationship between stiffness of spring and the vibration of angular velocity are no trend of monotonic increasing or decreasing,while the moving distance of the roll decreses with the increasing of the stiffness.This paper provides a new method to select and optimize the stiffness of spring safety device in roll crusher.
Spring safety device as the roll crusher's key component,the value of spring stiffness has a very important impact on the performance of the whole device,when the spring-loaded is too large,the wear is intensified and the power consumption is increased;while small spring force will increase the number of articles whose dimeter are bigger than the averige value.Aiming at this problem,the relationship between different stiffness of spring and the vibration of angular velocity of the moving roll and its moving distance were studied through simulation analysis based on the ADAMS softwear by setting five different spring stiffness.To simulate the working condition of the crusher,random signal was applied.The simulation results show that the relationship between stiffness of spring and the vibration of angular velocity are no trend of monotonic increasing or decreasing,while the moving distance of the roll decreses with the increasing of the stiffness.This paper provides a new method to select and optimize the stiffness of spring safety device in roll crusher.
2012, 31(12): 2044-2047,2052.
Abstract:
In the process of sheet metal bending forming,bending force directly influences the forming equipment choice and the reduction of bending force can effectively decrease the loss of forming equipment.Through setting a certain warm forming assumptions,the warm forming of bending parts with overlapped corner of TZM alloy sheet was numerically simulated.The change rule of bending force was studied,and the influence on bending force by some parameters such as blank opening depth,punch fillet radius and punch round radius,friction coefficient was analyzed.The results show that the change rule of bending force is basically consistent under different parameters;blank opening depth,punch fillet radius and punch rounded corner radius only have impact on max bending force,but friction coefficient has impact on bending force of whole forming process.Max bending force is inversly proportional to blank opening depth,punch fillet radius and punch round radius,and proportional to friction coefficient.
In the process of sheet metal bending forming,bending force directly influences the forming equipment choice and the reduction of bending force can effectively decrease the loss of forming equipment.Through setting a certain warm forming assumptions,the warm forming of bending parts with overlapped corner of TZM alloy sheet was numerically simulated.The change rule of bending force was studied,and the influence on bending force by some parameters such as blank opening depth,punch fillet radius and punch round radius,friction coefficient was analyzed.The results show that the change rule of bending force is basically consistent under different parameters;blank opening depth,punch fillet radius and punch rounded corner radius only have impact on max bending force,but friction coefficient has impact on bending force of whole forming process.Max bending force is inversly proportional to blank opening depth,punch fillet radius and punch round radius,and proportional to friction coefficient.
2012, 31(12): 2048-2052.
Abstract:
A novel algorithm using local shape distribution was proposed to address the problem of indicating the similarity of model's local parts in 3D CAD model retrieval.Firstly,sampling points were randomly chosen in the surface of a model.Then,for each sampling point and all points in its neighborhood,their geodesic distances were calculated,and a local shape distribution histogram was created accordingly.Finally,the similarity between two models was determined by the likeness of their all corresponding local shape distribution histograms.The experimental results demonstrate that the proposed method obtains better retrieval performance compared to the state-of-the-art.
A novel algorithm using local shape distribution was proposed to address the problem of indicating the similarity of model's local parts in 3D CAD model retrieval.Firstly,sampling points were randomly chosen in the surface of a model.Then,for each sampling point and all points in its neighborhood,their geodesic distances were calculated,and a local shape distribution histogram was created accordingly.Finally,the similarity between two models was determined by the likeness of their all corresponding local shape distribution histograms.The experimental results demonstrate that the proposed method obtains better retrieval performance compared to the state-of-the-art.
2012, 31(12): 2053-2056,2060.
Abstract:
Based on the theory of interference for stress-strength distribution,this paper established reliability models of important parts which consists of all important parts such as gears,planetary axes,bearings and splines in planetary transmission.Whole system reliability was formulated on the combination with system reliability theory and characteristic of hybrid system of multi-stage planetary transmission.And corresponding analysis software compiled with VC+ + was developed,with which self-developed and foreign pitch gearbox for wind turbine and foreigners were analyzed to have the same reliability.Through the reliability analysis results,system reliability can be up-grading by improving weak parts,which supports the reliability optimization.
Based on the theory of interference for stress-strength distribution,this paper established reliability models of important parts which consists of all important parts such as gears,planetary axes,bearings and splines in planetary transmission.Whole system reliability was formulated on the combination with system reliability theory and characteristic of hybrid system of multi-stage planetary transmission.And corresponding analysis software compiled with VC+ + was developed,with which self-developed and foreign pitch gearbox for wind turbine and foreigners were analyzed to have the same reliability.Through the reliability analysis results,system reliability can be up-grading by improving weak parts,which supports the reliability optimization.
2012, 31(12): 2057-2060.
Abstract:
Based on the conservation of mass and momentum,software Fluent and large eddy simulation(LES) was applied to study the development of jet flow in the tapered barrel and near the nozzle.The result shows that in consideration of the structure of barrel and nozzle,we can get similar structure between simulation and experiment by gas-liquid two-phase LES method;the tapered barrel can add the velocity of the jet flow,decrease the velocity gradient and improve the jet flow stability.So it can improve the performance of pulsed anti-riots water cannon apparently.
Based on the conservation of mass and momentum,software Fluent and large eddy simulation(LES) was applied to study the development of jet flow in the tapered barrel and near the nozzle.The result shows that in consideration of the structure of barrel and nozzle,we can get similar structure between simulation and experiment by gas-liquid two-phase LES method;the tapered barrel can add the velocity of the jet flow,decrease the velocity gradient and improve the jet flow stability.So it can improve the performance of pulsed anti-riots water cannon apparently.
