Hi all, I´m a researcher in computational biology thinking on topics quite far from my field. I want to model long thin-walled tubes of dimensions like those treated here, for example: ≈2 m long, radius ≈50mm and thickness ≈1mm. The tubes I´m interested in should be made of pulltruded/pullwinded carbon fibre. The material properties would be like those shown here: http://www.cstsales.com/rod_comp.html http://carbonfibretubes.co.uk/technology.html http://www.exelcomposites.com/Englis...oundTubes.aspx [Broken] Unfortunately, after having a quick look at the excellent documents suggested by AlephZero and Enthalpy in a related thread (https://www.physicsforums.com/showthread.php?t=662216), the formulas given therein seem either appropriate for isotropic materials, like those found in Timoshenko's theory for shell buckling, or too complex, like the NASA design codes for composites. 1. Is there any simple way to model the local buckling of thin-walled tubes made of unidirectional pulltruded/pullwinded carbon fibres? 2. If possible, what Poisson coefficient (μ) would be used in the formula σ=(e/R)*E/(3(1-μ2))0.5 for this kind of composites? (where "σ" is the stress, "e" thickness, "R" radius, and "E" Young´s modulus) Thanks a lot in advance! Any help would be really appreciated!