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From:
Bushnell, D. and Rankin, C. C.: “Use of GENOPT and BIGBOSOR4 to obtain optimum designs of an axially compressed cylindrical shell with a composite truss-core sandwich wall,” AIAA Paper No. AIAA 2011-1811, 52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, Denver, Colorado, April 4 - 7, 2011.
ABSTRACT: GENOPT/BIGBOSOR4 is applied to the problem of an axially compressed perfect elastic cylindrical shell the wall of which is a composite truss-core sandwich. The truss-core sandwich is constructed of trapezoidal core tubes that are sandwiched between two face sheets. At the junction of the core webs and the face sheets are “noodle” regions that are filled with unidirectional composite material. The design constraints are local buckling, general buckling, and five stress constraints for each material. Local and general buckling are computed from BIGBOSOR4 models in which the "huge torus" prismatic representation of the cylindrical shell is employed. In both the local and general buckling models the "huge torus" representation of the cylindrical shell consists of a number of identical modules of the cross section of the truss-core sandwich wall that are strung together along the curved meridian of the "huge torus". The rather elaborate 22-segment module used for local buckling includes small curved and straight segments that occur at the corners of the trapezoidal tool around which the truss-core is wrapped during the fabrication process. The presence of "noodles" that fill the prismatic triangular-like gaps between adjacent trapezoids is accounted for.
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