Pretest Prediction Composite Hat

HyperSizer requires only one, coarsely meshed, 2-D FEM

Only one coarse FEM was required and built to compute running loads for all of HyperSizer's failure predictions. The generalized stiffness terms of the 2-D model included the facesheet and coresheet ply layups, and the beginning and ending locations of the ply drop offs of the hat construction including the additional plies placed in the hat crown. The mesh density for HyperSizer's purpose can be rather coarse because only the static, FEA multiaxial force distribution is required for its analyses, including buckling. The explicit, buckling predictions of HyperSizer includes unsymmetric and bending-twisting stiffnesses and their couplings in both the stiffness formulations and eigenvalue analyses, and as such overcome the shortcomings identified above with the 3rd FEM that was using beam/rod elements for the hat stringers. For verification, an MSC/NASTRAN eigenvalue solution was performed and compared well to the HyperSizer panel buckling solution, as shown.

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