NACA TN 3781 Plate Buckling (1957)

The NACA TN 3781 Plate Buckling (1957) implementation in SDC Verifier checks the buckling stability of flat plates under combined in-plane loading, including both elastic and inelastic (plastic) buckling behavior. The check is performed directly in the FEA workflow using recognized plate geometry, converted stresses, and user-defined stability parameters instead of separate manual calculations. 

Using Panel Finder, SDC Verifier identifies sections and plates together with their dimensions. The implementation then evaluates each plate using recognized geometry, element thickness, converted stress directions, and the selected material-stiffness assumptions required for the NACA method. 

What this implementation checks 

• Buckling stability of flat plates under combined in-plane loading 
• Elastic buckling behavior using elastic stiffness assumptions 
• Inelastic / plastic buckling behavior using secant and tangent modulus inputs 
• Plate response using converted element stresses or plate-average stresses 
• Stability sensitivity to boundary-condition-based buckling coefficients 

How it works in SDC Verifier 

The check is calculated on recognized sections. With Panel Finder, SDC Verifier automatically identifies plates and their dimensions, where length is taken as the longest plate edge and width as the longest perpendicular to that edge. 

Calculations are performed for each element using stresses converted into the plate coordinate system or, if selected, using plate-average stresses. Plate thickness is taken directly from each element unless a manual thickness value is defined by the user.