Copyright 1997, American Institute of Aeronautics and Astronautics, Inc.

CHOOSEPLOT (user chooses what

The "localbuck(vinson)" margin provides a parallel prediction of what PANDA2 has always computed with analysis type IQUICK=1, that is, local buckling analysis of the panel module segments with use of Eq.(57) in [21] with subsequent "knockdown" as described in Section 8.2 of [14] to account for the effect of transverse shear deformation. For local buckling of the panel skin, the previously (and still) available PANDA2 margins that represent the same phenomenon as "localbuck(vinson)" read: buck.(donl) simp-support local buck... buck.(sand) simp-support local buck... in which the string "DONL" means "Donnell theory" and "SAND" means "Sanders theory".

The stresses, <T zl, T^p and T j play a significant role in the stress constraints to be discussed later in the subsection entitled "Additional

curvature give rise to tension in the core normal to the face sheets.

"sandwichcore tension margin...". IMPLEMENTATION

BEGIN Introduce

implementation of the "sandwich" capability occur in SUBROUTINE BUCPAN. strain energy in a manner analogous to that done in BUCPAN2 Introduce the elastic foundation modulus term, EFOUND^, into the coefficient a 33 (see Eq. 55f, p.

the constraint conditions involving the maximum allowable

deformation-induced sandwich core crushing pressure. (See discussion above associated with Eqs.(31) - (33)). SUBROUTINE STRCON was modified to compute x-z and

some negative margins, provided that

transverse shear deformation is neglected. Since the width/thickness ratio

margins remain essentially the same. Those that are significantly affected by the introduction of finite initial face sheet waviness, W 0 / L = 0.001, are the core crushing margin, the x-z ("L-direction") core transverse shear stress margin,

which a reasonable level of initial facesheet waviness is present. The results for the final optimum design are listed in Table

(bottom facesheet has higher destabilizing resultants than

while the work was in progress. Dr. Frank Weiler helped

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