Tube Layup symmetry

General Composites Discussions Engineering Talk
#1

Hi,

I’m confusing myself with layup symmetry for making tubes and would appreciate some help.

Say for example I have 2x 0 degree layers, +/-45 layers, 1x90 degrees. What is the best order to put them in a tube to create the stiffest tube, or what are the merits of different orders

[0, +45, 90, -45, 0] is symmetrical, but doesn’t maximise the effect of the first 0 degree layer?..

[90, +45, -45, 0, 0] keeps the 0 degree layers at the surface so their impact on the stiffness should be mazimised, is that correct? But it’s not symmetrical, but…

[+45, -45, 0, 0, 90] is also interesting because the 90 layer should prevent delamination as the tube bend increases? But having a 90 next to a zero isn’t ideal because it can introduce decoupling stresses?

Any thoughts?

Thanks

#2

I don’t think chasing laminate symmetry in tubes is necessary.

Unlike the flat panels a tube is still going to hold its tubular shape even with an unbalance laminate.