Sandwich Core Analysis
Sandwich Core Analysis
(OP)
Any help on determining the tensile and shear allowables for a sandwich core? I am using a sandwich core that consists of carbon plies for the skin and Rohacell W70 as the core. The part is in direct shear and torsion. I have the part analyzed on FEA Nastran, and am trying to determine the allowables for the entire part. All the materials/text books I have are how to determine the actual stresses on the part, but little to none is mentioned on how to determine the allowables. Any help would be much appreciated.





RE: Sandwich Core Analysis
However, all sandwich construction is extremely process dependent and "allowables" for your entire part need to be determined by testing samples that were made using production materials, processes and tooling.
SuperStress
RE: Sandwich Core Analysis
RE: Sandwich Core Analysis
Wes C.
RE: Sandwich Core Analysis
RE: Sandwich Core Analysis
Contact the panel mfr. They should have (a limited amt) of data. Short of that, you may want to look for mfr's with similar materials. This may give you "ballpark" figures... That said, it may be the difference between home plate and left field.
Wes C.
RE: Sandwich Core Analysis
RE: Sandwich Core Analysis
RE: Sandwich Core Analysis
In terms of what you do with the numbers. How have you modelled it? This will influence how you treat the allowables.
RE: Sandwich Core Analysis
RE: Sandwich Core Analysis
RE: Sandwich Core Analysis
RE: Sandwich Core Analysis
RE: Sandwich Core Analysis
For strength assessment you just compare the core though-thickness compression allowable with the foam limit and the corresponding transverse (13, and 23) shear allowables. If you haven't set your shell properties up properly you won't have these through-thickness stress results.
RE: Sandwich Core Analysis
RE: Sandwich Core Analysis
Steven Fahey, CET
RE: Sandwich Core Analysis
However a little practical knowledge never hurts.
From my experience repairing accident damage, Rohacell core nearly always fails by the cells disintegrating at the bond line between the face plys.
Secondary failure in bending is a crack across the core. I do not know how this compares to an FEA prediction. And what I have said will not of course apply to every situation. It may give someone a starting point.
B.E.