Optimization of Bonded Patch to Cylindrically Curved Shell Structure.

摘要

Adhesive bonding has been used to join or repair metallic and composite structural components to achieve or restore their designated structural stiffness and strengths. However, current analysis methods and empirical databases for composite bonded patch repair or joints are limited to flat structures, and there exists a very limited knowledge on the effect of curvature on the performance and durability of composite bonded joints and repairs. Recently, a novel finite element formulation was presented for developing adhesive elements for conducting 2.5-D simplified stress analysis of bonded repairs to curved structures. This report presents the work on optimal design of bonded composite patch using the newly developed adhesive element. Three types of design variables considered separately are (a) geometrical boundary shape of bonded composite patch, (b) ply drop-offs contour of bonded composite patch, and (c) fiber orientation of each ply in bonded composite patch. Sequential Linear Programming (SLP) method and one-dimensional direct search method are employed as the optimization algorithm in conjunction with a fully implemented mesh generation algorithm into which new features were incorporated. Several different objective functions were proposed to optimize the bonded patch.