Venation Growth Algorithm For Stiffener Layout In Plate Structure

Traditional orthogonal pattern is ordinarily employed in stiffener configurations of platesin engineering. Layout optimization design of the stiffeners can realize a win-win situation ofstructure lightweight and bearing property. The existing methods generally transform thechallenge into strengthening regional distribution, and the resulting vague regions needidentification by post-processing technology and understanding of the designer to redesign.The idea of biological adaptive growth has been applied to the layout design of stiffeners inplate, by which legible reinforcement distributions are can be obtained. Structure similarityexists between dicotyledonous venation pattern and irregular stiffener distribution. Thedissertation extracted some mechanical factors from the topology regularity andmorphogenesis theory of dicotyledonous venation, and applied them to the stiffener layoutoptimization. Then typical plate examples were designed for proper stiffener distribution, anddifferent layout pattern were compared through static experiment. Specific research work is asfollows:Parametrized geometric model was established for irregular ribs in plate structure.Similarity analysis was conducted between irregular ribs and dicotyledonous venation, sodicotyledonous venation is chosen as bionic object. Full discrete plate-beam structure wasadopted in structural analysis of stiffened plate. Comparative analysis of mechanicalproperties of different plant venation under wind and rain loads shows the enhancement oflamina with dicotyledonous venation configuration. Local topology regularity and mechanicalforce hypothesis of dicotyledonous venation morphogenesis formation was elaborated, fromwhich mechanical factors were extracted, on the basis of them static and dynamic bionicmechanical model was constructed for bionic rib pattern.On the basis of full discrete beam-plate structure, layout optimization model of irregularstiffeners was presented. Based on static bionic mechanical model, a new venation growthmethod with hierarchical veins was proposed, in which mainvein grown toward minimumstrain energy, subveins grown in order to eliminate local shear stress, and vectorialequilibrium equation function as amendment rules in the bifurcation. The premises andconcepts of venation growth algorithm were clarified. A parametric study discussed the seedposition selection of the main vein and secondary veins, the setting of the volume amount, implementation way of vectorial equilibrium equation. And growth rules and implementationprocess were mapped. The resultant dicotyledonous venation-like pattern of oval-shapedlamina shows that the proposed method can simulate the mainvein and subveins ofdicotyledonous venation roughly. Square plates simply supported along four edges weredesigned for proper stiffener layout, and the reason for different pattern beween otherresearchs was explained.In order to improve the calculation efficiency, sensitivity number was applied on thealgorithm, after implementation the numbers of finite element analysis are greatly reduced,and the computing time are also shorten. Realization process of the proposed method wasimproved, and the parameter of convergence accuracy was set to avoid endless loop. Typicalsquare plates under different loads and different constraints were calculated as to get optimalstiffener layout. The resultant rib configuration is simple and clear, and suitable for processing.The ribs results consist with the distributions by variable density topology optimization,which show the adaptability of the algorithm for different working conditions.Static testing system of stiffened plate was designed, with which comparative test ofstiffened panels with different configuration was conducted. Comparison analysis wasexecuted between stiffened plate clamped at four corners with traditional pattern and finiteelement numerical results indicate the experimental data and numerical solutions arecongruent under incremental loads. Two groups of square plate workpieces with equal widthand equal height were compared, and it is demonstrated that workpieces with equal heightbehave better strengthening effect. Square plates clamped at four corners and cantileversquare plate with different rib configuration were measured, and the data of the displacement,strain and stress were collected and analyzed, the results show that the pattern got by venationgrowth algorithm are better than traditional configuration. The reinforcement effectiveness ofVGA-based stiffener layout in the plate is demonstrated.