Shape Optimization And Stability Analysis Of Double-layer Cylindrical Shell

Shell structure is a spatial structure of systems formed which the bar regularly arrange along the surface and connected by the nodes, It have inherent properties of truss structure and thin shell. Structure of the shell have a series of advantages,such as cover a large span, reasonable space force, different forms of surface of shell structure can provide beautiful shape and full of artistic expression, which is the most widely used type of spatial structure of large, cross-architecture now.Structural optimization is seek the best solution from a number of possible solutions under the conditions of the program. It is based on a variety of practical problems of engineering structures to establish the corresponding mathematical model, using optimization techniques, to find the optimal solution under a variety of constraints. Compared with the traditional design, because of its advantages of reasonable design, material saving,now have a wide range attention at home and abroad in engineering field.In this paper, the shape optimization has been done of double-layer cylindrical shell, And has analyed the stability of optimized pyramid cylindrical shell. First, we use finite element analysis software ALGOR to analysis Static characteristics of the double-layer cylindrical shell, With loss of cross-over and thickness-span ratio changes, force characteristics and displacement characteristics of dome can be obtained. It can provide the basis for selection of dome structure for the following initial macroscopic surface shape optimization parameters.Then for the Double-layer cylindrical shell features, we proposed two-stage algorithm of shape optimization of Double-layer cylindrical shell structure.The first level optimization in a fixed geometric shape, using the discrete variable optimization of one-dimensional search algorithm and the relative difference quotient for cross-section; In the second level optimization, because the Double-layer cylindrical shell have many of the nodes, we convers design variables from the surface shape parameters into a node coordinates,and height and thickness as design variables of the structure using a continuous variable complex method for shape optimization,And verified the effectiveness and reliability of the algorithm by the example. Then using the above algorithm to do shape optimization of five Double-layer cylindrical shell which commonly used in engineering. Obtained ratio of height to span ratio and the ratio of thickness of five Double-layer cylindrical shell under different mesh sizes and different span,And the different forms of Double-layer cylindrical shell structures optimized steel volume per unit area, which have a certain reference value of Double-layer cylindrical shell shell design and selection.Shell structure stability is the key issue in structural design, Single-layer shell and Double-layer shell with a smaller thickness possible instability,especially when the span is large, stability will be more prominent. Finally, we analyse Square Pyramid cylindrical shell which was optimized before and after using ALGOR software of the linear and nonlinear buckling. Determined buckling load optimization and buckling modes of shell before and after optimized. verify the security and reliability of the structure of Double-layer cylindrical shell after optimized.