How would I analyze the torsional stiffness of a sandwich panel with a specific layup of carbon fiber face sheets? It seems very hard to find anything about how to calculate this.
Good question. I am working on the second edition of my Composites Handbook, and it will include detailed analysis of fasteners in sandwich, which involves similar analysis techniques. Meanwhile… you need to remember that the facesheets carry all in-plane load, and the core carries out of plane load. Therefore, torsion must be carried as differential bending. Imagine the torque carried by a “couple” of facesheet shears in the plane of the facesheet, such that S=T/h. Then Fs=S/bt. If you need more strength, you could divide the beam width in half, evaluate half for bending upward and half for bending downward. Sum the capability for in-plane facesheet shear with the capability for out of plane bending, and poof! Approximate answer! Alternately, calculate the stiffness for each assumption, and divy up the shear by the relative stiffnesses for a better answer. My handbook does not yet cover this, and i was not planning to add that to the second edition, but I’ll see what i can do.
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How would I analyze the torsional stiffness of a sandwich panel with a specific layup of carbon fiber face sheets? It seems very hard to find anything about how to calculate this.
Good question. I am working on the second edition of my Composites Handbook, and it will include detailed analysis of fasteners in sandwich, which involves similar analysis techniques.
Meanwhile… you need to remember that the facesheets carry all in-plane load, and the core carries out of plane load.
Therefore, torsion must be carried as differential bending.
Imagine the torque carried by a “couple” of facesheet shears in the plane of the facesheet, such that S=T/h. Then Fs=S/bt.
If you need more strength, you could divide the beam width in half, evaluate half for bending upward and half for bending downward.
Sum the capability for in-plane facesheet shear with the capability for out of plane bending, and poof! Approximate answer!
Alternately, calculate the stiffness for each assumption, and divy up the shear by the relative stiffnesses for a better answer.
My handbook does not yet cover this, and i was not planning to add that to the second edition, but I’ll see what i can do.