Formulas for the elastic constants of plates with integral waffle-like stiffening

Formulas are derived for the fifteen elastic constants associated with bending, stretching, twisting, and shearing of plates with closely spaced integral ribbing in a variety of configurations and proportions. In the derivation the plates are considered, conceptually, as more uniform orthotropic plates somewhat on the order of plywood. The constants, which include the effectiveness of the ribs for resisting deformations other than bending and stretching in their longitudinal directions, are defined in terms of four coefficients, and theoretical and experimental methods for the evaluation of these coefficients are discussed. Four of the more important elastic constants are predicted by these formulas and are compared with test results. Good correlation is obtained. (author

NACA Technical Notes

"The sandwich plate consisting of corrugated sheet fastened between two face sheets is considered. Application of existing theories to the analysis of such a sandwich plate requires the knowledge of certain elastic constants. Formulas and charts are presented for the evaluation of these constants" (p. 1)

NACA Technical Notes

"An analysis is made and charts are presented for the determination of regions of efficient application of flat balsa-core sandwich and stiffened-panel construction for a large range of design requirements. Optimum sandwiches are found to have relatively low values of the ratio of core thickness to face thickness" (p. 1)

NACA Technical Reports

"Formulas are derived for the fifteen elastic constants associated with bending, stretching, twisting, and shearing of plates with closely spaced integral ribbing in a variety of configurations and proportions. In the derivation the plates are considered, conceptually, as more uniform orthotropic plates somewhat on the order of plywood. The constants, which include the effectiveness of the ribs for resisting deformations other than bending and stretching in their longitudinal directions, are defined in terms of four coefficients, and theoretical and experimental methods for the evaluation of these coefficients are discussed" (p. 1)

NACA Research Memorandums

Report presenting formulas for fifteen elastic constants associated with bending, stretching, twisting, and shearing of plates with closely spaced integral ribbing in a variety of configurations and proportions. Four coefficients are provided for each rib and the experimental means of determining them are described

NACA Technical Notes

"Direct-reading design charts are presented for 24S-T aluminum-alloy flat compression panels having longitudinal straight-web Y-section stiffeners. These charts make possible the direct determination of the stress and all the panel proportions required to carry a given intensity of loading with a given skin thickness and effective length of panel" (p. 1)