Analysis and Optimum Design of Composite Grid Structures

Abstract

An integrated equivalent stiffness model is developed to describe a grid structure with or without laminate skins. The in-plane bending and shear of ribs are included without introducing any extra degree of freedom so that Mindlin's plate theory can still be adopted. As a result, the model can be directly incorporated with the existing FEM technique and take advantage of commercial codes. The proposed model is demonstrated to be efficient and reasonably accurate. If high precision is required, the equivalent stiffness model can be incorporated with the exact FEM modeling to obtain a refined stress analysis. Hygrothermal behavior and local buckling are also taken into account. Using the model as a tool, the performance of composite grid structures can be compared to traditional laminates, sandwich plates and metal grid structures. A method of optimum design is established to design a grid structure with or without laminated skins. Multiple loads and multiple failure mechanisms are considered. Discrete design is also included. Furthermore, the method can be easily incorporated with FEM to perform structural optimization. The optimization code is demonstrated to be a very powerful design tool. Finally, a user-friendly computer code is developed to perform the above tasks.

High Strength Wood-based Sandwich Panels Reinforced with Fiberglass and Foam

“…Many sandwich panels are fabricated using foam or honeycomb construction as the core structure. However, over the past 15 years, research has demonstrated that a new interlocking composite grid arrangement could offer improved performance for some applications, particularly for large civil structures (Han and Tsai 2003;Chen and Tsai 1996). This interlocking grid uses linear ribs that are double slotted 1/3 from each edge across the width or single slotted 2/3 from one edge across the width of the rib.…”

Formation and Calculation Analyses of the Cylindrical Latticed-Built-Up-Member-System Reticulated Mega-Structure

“…So the hinge-connection layout style is superior to the independent one for the substructures in the case of the upper chord latticed built-up members of the main structure being cancelled. This kind of structure, in which the substructures are laid out by hinge-connection style and participate in bearing load cooperatively with the web and lower chord latticed built-up members of the main structure, is similar to the composite grid structure (Chen [17]). The substructures of the former correspond to the reinforced concrete upper chord boards of the latter.…”

Optimization of nonhomogeneous facesheets in composite sandwich plates

“…Among the numerical methods available, two are most fiequently applied in optimization solutions of composite stnictures: the Finite Element Method -FEM [13,17,22,23,50,68,85,97,98] and the Ritz Method [l, 64,103,104] . The Ritz Method was used in this work because it generates a solution that demands less computer time.…”