Research On Stress And Deformation Analysis And Structure Optimized Design Of Flat Receptacle

Monolithic aluminum alloy wallboard has got extensive use in manufacturing because of its advantages of high strength/density ratio, fine airtightness, unfailing performance and attractive appearance. It is mainly formed through extruding by combined flat receptacle, which is easy to crack under severe condition of high temperature, high pressure and high fricition. Nowadays, as a result of knowing the stress and deformation distribution of flat receptacle incompletely, poor intensity and short working life of the receptacle limit the application and generalization of this extruding process. In order to improve the strength and prolong the working life of the flat receptacle, we should analyze its stress and deformation distribution with accuracy, and then optimize its structural dimensions. It is advantageous to make full use of the material potential of the receptacle and make sure of getting its best working performance.Taking the combined flat receptacle as subject investigated, the extruding forming law of the wallboard and the stress and deformation distribution of the flat receptacle are analyzed completely with numerical simulation and physical simulation. Then through introducing the thoughtway of neural network (NN) and genetic algorithms (GA), the structural dimensions of three-layer combined flat receptacle are optimized. Some important and practical conclusions and achievements are obtained.Firstly, the basic theoretics of rigid-plastic finite element method (FEM) is given. Taking it as theoretical basis of numerical simulation for the flat receptacle, some key technologies during the implementation are discussed and the corresponding methods of resolution are put forward.Rigid-plastic and elastic-plastic FEM are applied into complex problem analysis of wallboard forming by flat receptacle. At first, by right of software MSC.SuperForm, wallboard extruding forming process is simulated and the inner pressure distribution of the receptacle acted by the blank is obtained along the axial and circumferential directions of the receptacle respectively. Then, by the aid of software ANSYS, introducing the forementioned inner pressure distribution law as one of the boundary conditions, the heat-structure coupling analysis of combined flat receptacle under the nonuniformly distributed pressure is realized by APDL language programming. So, the stress and deformation distribution of three-layer flat receptacle influenced by heat, interference fit and nonuniformly distributed pressure are acquired. The analysis involving all aspects not only guarantees the relativity, but also gains the full data of the whole process. Since all those influence factors are taken into account at the same time, the numerical simulation reflects the receptacle status objectively, which offers the necessary technique support to subsequent optimum design of flat receptacle structural dimension.Research on deformation law of mould cavity is done for two kinds of structures of combined flat receptacle with circular shaped lining and elliptic shaped lining respectively with contactelement method offered by ANSYS. Aiming at nonuniform deformation of mould cavity, a structure improvement project, roundness design method, is brought forward. That is, adopting flat receptacle with elliptic shaped lining instead of circular shaped lining uniformizes the deformation distribution, which will enhance the dimensional accuracy of the flat receptacle and simplify the workload of the mould repair in manufacturing.In order to verify the accuracy of the above numerical simulation, physical simulation is done from two aspects. On the one hand, simulate the wallboard extruding process to find the action mode of extrusion pressure and the distribution of inner stress of flat receptacle by photoelastic experiment. On the other hand, simulate the interference fitting process to get the deformation distribution of the mould cavity by steel mould correlation method. The experimental results accord with the numerical simulation results, which indicates that numerical simulation exactitude is satisfying. Furthermore, using the extrusion pressure distribution by photoelastic experiment as one of the boundary conditions in FEM analysis instead of foregoing uniform extrusion pressure hypothesis to solve the stress field of flat receptacle will enhance the computational accuracy, which also makes the optimum design of extrusion die more reasonable.Finally, the ideas of NN and GA are introduced into structural dimensions optimization for flat receptacle. Orthogonal experiment is designed according to the main influencing factors such as the diameters of each layer, shrink range and working pressure. Then, a BP neural net is trained on the flat of Matlab7. 0 to find the mapping relationship from structural dimensions and extrusion pressure to the maximum of equivalent stress in the receptacle. Afterwards, the structural dimensions of the receptacle are optimized using GA in terms of constant strength design philosophy. A feasible intelligent design method is attained, through which the reasonable diameter of each layer and the best value of each fitting allowance for the three-layer flat receptacle are decided. It offers a new approach to optimum design for complex nonlinear problems.The research results can guide the optimum design of flat receptacle. Furthermore, it improves the extruding die design theory for wallboard.