Stiffened structures

We usually must go beyond the simple concept of a monocoque or single-thickness skin for whatever structure we design. That is, we must usually consider the bending stiffness, and, to achieve structural efficiency, we often must stiffen a structure in some manner. We will first address the terminology of stiffening and how it is used. Then, we will consider the types of stiffeners that could be used. Next, an important issue that arises in the design of stiffeners is whether the stiffener has an open- or a closed-cross section. Then, we will address some of the 

Stiffener design parameters and some design considerations for stiffeners. Finally, we will examine a new concept for stiffening composite structures, namely orthogrid. 

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The trimer is a useful stiffening structure in some polyurethanes. Phosphine oxides or phosphates can convert an isocyanate to a carbodiimide (2.28). This is used com-... 

Studies performed at the University of Missouri-Rolla in conjunction with Rockwell Scientific have shown FSP to produce a hne-grain-size material and create low-temperature, high-strain-rate superplasticity in aluminum and titanium alloys. The PNNL is currently investigating the application of this FSP-induced superplasticity in the fabrication of large, integrally stiffened structures. 

Huybrechts SM, Hahn SE, Meink TE. Grid-stiffened structures a survey of fabrication, analysis and design methods. In Proceedings of 12th international conference on composite materials (ICCM), Paris France 1999. 

Out-of-plane joints have been reviewed by Junhou and Shenoi, mainly in the context of marine structures [47]. The most common marine topologies are the monocoque or top-hat stiffened structures, using single skin glass/ polyester or vinyl ester laminates, and the sandwich or double wall structures with a foam core. The authors illustrate six different kinds of out-of-plane joints used in this context with FRP. 

Huybrechts, S.M., Meink, T.E., Wegner, P.M., and Ganley, G.M. (2002) Manufacturing theory for advanced grid stiffened structures. Composites Part A Applied Science and Manufacturing, 33, 155-161. 

Vaicaitis, R. and Lyrintzis, C. S., Response of Discretely Stiffened Structures, AIAA/ASME/ASCE/AHS 28th Structures, Structural Dynamics Materials Conference Paper No. 87-0914, Monterey, California, April 6-8, 1987. 

Core support structure The grid plate is supported on the core support structure (CSS) which also supports the shielding subassemblies via the auxiliary grid plate and the irmer vessel. It is a radially stiffened structure supported on the main vessel bottom by a cylindrical shell. 

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