Feature recognition aims at extracting manufacturing features with geometrical information from solid model and is considered to be an efficient way of changing the interactive NC machining programming mode.Existing r...Feature recognition aims at extracting manufacturing features with geometrical information from solid model and is considered to be an efficient way of changing the interactive NC machining programming mode.Existing recognition methods have some disadvantages in practical applications.They can essentially handle prismatic components with regular shapes and are difficult to recognize the intersecting features and curved surfaces.Besides,the robustness of them is not strong enough.A new feature recognition approach is proposed based on the analysis of aircraft integral panels＇ geometry and machining characteristics.In this approach,the aircraft integral panel is divided into a number of local machining domains.The machining domains are extracted and recognized first by finding the principal face of machining domain and extracting the sides around the principal face.Then the machining domains are divided into various features in terms of the face type.The main sections of the proposed method are presented including the definition,classification and structure of machining domain,the relationship between machining domain and principal face loop,the rules of machining domains recognition,and the algorithm of machining feature recognition.In addition,a robotic feature recognition module is developed for aircraft integral panels and tested with several panels.Test results show that the strategy presented is robust and valid.Features extracted can be post processed and linked to various downstream applications.The approach is able to solve the difficulties in recognizing the aircraft integral panel＇s features and automatic obtaining the machining zone in NC programming,and can be used to further develop the automatic programming of NC machining.展开更多
In order to design the press bend forming path of aircraft integral panels,a novel optimization method was proposed, which integrates FEM equivalent model based on previous study,the artificial neural network response...In order to design the press bend forming path of aircraft integral panels,a novel optimization method was proposed, which integrates FEM equivalent model based on previous study,the artificial neural network response surface,and the genetic algorithm.First,a multi-step press bend forming FEM equivalent model was established,with which the FEM experiments designed with Taguchi method were performed.Then,the BP neural network response surface was developed with the sample data from the FEM experiments.Furthermore,genetic algorithm was applied with the neural network response surface as the objective function. Finally,verification was carried out on a simple curvature grid-type stiffened panel.The forming error of the panel formed with the optimal path is only 0.098 39 and the calculating efficiency has been improved by 77%.Therefore,this novel optimization method is quite efficient and indispensable for the press bend forming path designing.展开更多
The sonic fatigue life of the aluminium rectangular panel was calculated using the concise method[1], and the sonic fatigue test was conducted on progressive wave tube (PWT) test facility. A comparison was made betwee...The sonic fatigue life of the aluminium rectangular panel was calculated using the concise method[1], and the sonic fatigue test was conducted on progressive wave tube (PWT) test facility. A comparison was made between the results of calculation and test, and it shows reasonable agreement between these two results.展开更多
Build-up panels for the commercial aircraft fuselage subjected to the axial compression load are studied by both experimental and theoretical methods.An integral panel is designed with the same overall size and weight...Build-up panels for the commercial aircraft fuselage subjected to the axial compression load are studied by both experimental and theoretical methods.An integral panel is designed with the same overall size and weight as the build-up structure,and finite element models（FEMs）of these two panels are established.Experimental results of build-up panels agree well with the FEM results with the nonliearity and the large deformation,so FEMs are validated.FEM calculation results of these two panels indicate that the failure mode of the integral panel is different from that of the build-up panel,and the failure load increases by 18.4% up to post-buckling.Furthermore,the integral structure is optimized by using the multi-island genetic algorithm and the sequential quadratic programming.Compared with the initial design,the optimal mass is reduced by 8.7% and the strength is unchanged.展开更多
The riveting joint is one of the important joint methods to permanently fasten two thin-walled sheet-metal parts. It is most ba- sic to efficiently analyze and estimate the deformation of the riveting joint for the pe...The riveting joint is one of the important joint methods to permanently fasten two thin-walled sheet-metal parts. It is most ba- sic to efficiently analyze and estimate the deformation of the riveting joint for the performance, fatigue durability and damage of the riveting structure in the aircraft. This paper researches the riveting process mathematics modeling and simulating to more accurately analyze deformation of thin-walled sheet-metal parts. First, the mathematics and mechanics models for the elastic deformation, plastic deformation and springback of the rivet are built by mechanics theory. Second, on the basis of ABAQUS system, a finite element system, an instance made up of the rivet and two thin-walled sheet-metal parts of aluminum alloy is used to analyze and simulate the stress and deformation. What＇s more, a comparison is made between the results obtained by the mathematics and mechanics models and those by finite element method （FEM）. The models are proved true by the calculating and simulation results of the instance.展开更多
To reduce the damage of the pressurizing panel structure of a fuselage caused by an explosion at the“least risk bomb location”in an aircraft structure,a new pre-separation panel structure was designed to resist blas...To reduce the damage of the pressurizing panel structure of a fuselage caused by an explosion at the“least risk bomb location”in an aircraft structure,a new pre-separation panel structure was designed to resist blast loading.First,the dynamic strain response and morphology of impact damage of the new pre-separation panel were measured in an impact damage test.Second,the commercial software LS-DYNA was used to calculate the propagation of the blast shock wave,and the results were compared with empirical equations to verify the rationality of the numerical calculation method.Finally,the fluid–structure coupling method was used to calculate the damage process of the pre-separation panel structure under the impact of an explosion wave and an impact block.The calculated results were in good agreement with the test results,which showed the rationality of the calculation method and the model.The residual strength of the damaged pre-separation panel was significantly higher than that of the original damaged panel.The results show that the new pre-separation panel structure is reasonable and has certain significance for guiding the design of plenum chambers with strong resistance to implosion for aircraft fuselages.展开更多
文摘Feature recognition aims at extracting manufacturing features with geometrical information from solid model and is considered to be an efficient way of changing the interactive NC machining programming mode.Existing recognition methods have some disadvantages in practical applications.They can essentially handle prismatic components with regular shapes and are difficult to recognize the intersecting features and curved surfaces.Besides,the robustness of them is not strong enough.A new feature recognition approach is proposed based on the analysis of aircraft integral panels＇ geometry and machining characteristics.In this approach,the aircraft integral panel is divided into a number of local machining domains.The machining domains are extracted and recognized first by finding the principal face of machining domain and extracting the sides around the principal face.Then the machining domains are divided into various features in terms of the face type.The main sections of the proposed method are presented including the definition,classification and structure of machining domain,the relationship between machining domain and principal face loop,the rules of machining domains recognition,and the algorithm of machining feature recognition.In addition,a robotic feature recognition module is developed for aircraft integral panels and tested with several panels.Test results show that the strategy presented is robust and valid.Features extracted can be post processed and linked to various downstream applications.The approach is able to solve the difficulties in recognizing the aircraft integral panel＇s features and automatic obtaining the machining zone in NC programming,and can be used to further develop the automatic programming of NC machining.
基金Project(20091102110021)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘In order to design the press bend forming path of aircraft integral panels,a novel optimization method was proposed, which integrates FEM equivalent model based on previous study,the artificial neural network response surface,and the genetic algorithm.First,a multi-step press bend forming FEM equivalent model was established,with which the FEM experiments designed with Taguchi method were performed.Then,the BP neural network response surface was developed with the sample data from the FEM experiments.Furthermore,genetic algorithm was applied with the neural network response surface as the objective function. Finally,verification was carried out on a simple curvature grid-type stiffened panel.The forming error of the panel formed with the optimal path is only 0.098 39 and the calculating efficiency has been improved by 77%.Therefore,this novel optimization method is quite efficient and indispensable for the press bend forming path designing.
文摘The sonic fatigue life of the aluminium rectangular panel was calculated using the concise method[1], and the sonic fatigue test was conducted on progressive wave tube (PWT) test facility. A comparison was made between the results of calculation and test, and it shows reasonable agreement between these two results.
文摘Build-up panels for the commercial aircraft fuselage subjected to the axial compression load are studied by both experimental and theoretical methods.An integral panel is designed with the same overall size and weight as the build-up structure,and finite element models（FEMs）of these two panels are established.Experimental results of build-up panels agree well with the FEM results with the nonliearity and the large deformation,so FEMs are validated.FEM calculation results of these two panels indicate that the failure mode of the integral panel is different from that of the build-up panel,and the failure load increases by 18.4% up to post-buckling.Furthermore,the integral structure is optimized by using the multi-island genetic algorithm and the sequential quadratic programming.Compared with the initial design,the optimal mass is reduced by 8.7% and the strength is unchanged.
基金National Natural Science Foundation of China （50805119） Aeronautical Science Foundation in China （2010ZE53049） Fund of National Engineering and Research Center for Commercial Aircraft Manufacturing （SAMC11 -JS-07-200）
文摘The riveting joint is one of the important joint methods to permanently fasten two thin-walled sheet-metal parts. It is most ba- sic to efficiently analyze and estimate the deformation of the riveting joint for the performance, fatigue durability and damage of the riveting structure in the aircraft. This paper researches the riveting process mathematics modeling and simulating to more accurately analyze deformation of thin-walled sheet-metal parts. First, the mathematics and mechanics models for the elastic deformation, plastic deformation and springback of the rivet are built by mechanics theory. Second, on the basis of ABAQUS system, a finite element system, an instance made up of the rivet and two thin-walled sheet-metal parts of aluminum alloy is used to analyze and simulate the stress and deformation. What＇s more, a comparison is made between the results obtained by the mathematics and mechanics models and those by finite element method （FEM）. The models are proved true by the calculating and simulation results of the instance.
文摘To reduce the damage of the pressurizing panel structure of a fuselage caused by an explosion at the“least risk bomb location”in an aircraft structure,a new pre-separation panel structure was designed to resist blast loading.First,the dynamic strain response and morphology of impact damage of the new pre-separation panel were measured in an impact damage test.Second,the commercial software LS-DYNA was used to calculate the propagation of the blast shock wave,and the results were compared with empirical equations to verify the rationality of the numerical calculation method.Finally,the fluid–structure coupling method was used to calculate the damage process of the pre-separation panel structure under the impact of an explosion wave and an impact block.The calculated results were in good agreement with the test results,which showed the rationality of the calculation method and the model.The residual strength of the damaged pre-separation panel was significantly higher than that of the original damaged panel.The results show that the new pre-separation panel structure is reasonable and has certain significance for guiding the design of plenum chambers with strong resistance to implosion for aircraft fuselages.
