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This is Fig. 3a from the paper, "Use of GENOPT and BIGBOSOR4 to optimize weld lands in axially compressed stiffened cylindrical shells and evaluation of the optimized designs by STAGS" by David Bushnell and Robert P. Thornburgh, AIAA 51st Structures, Structural Dynamics, and Materials Conference, 2010, AIAA Paper 2010-2927.
This slide shows a schematic of a “huge torus” model. For most “huge torus” models, a good choice of RBIG is RBIG = 100xL/pi. The cylindrical shells studied in the 2010 paper just cited have RADIUS = 48 inches.
For the “true prismatic” shell model in BIGBOSOR4 the "huge torus" strategy is no longer used. Instead, the kinematic relationships for a true prismatic thin-walled structure were introduced into BIGBOSOR4 in 2010. This corresponds to RBIG = infinity. (See the next slide for more about the true prismatic shell model.)
Reference for the "true prismatic" shell model incorporated recently (2010) into BIGBOSOR4:
Bushnell, David, "Comparison of a "huge torus" model with a true prismatic model for: 1. an axially compressed simple monocoque cylindrical shell, 2. an axially compressed optimized truss-core sandwich cylindrical shell, and 3. an axially compressed optimized internally ring and stringer stiffened cylindrical shell with a T-stiffened weld land, Unpublished report for NASA Langley Research Center, February 12, 2010 and contained in the file, ...bigbosor4/case/prismatic/prismaticshell.pdf
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