Time and Temperature Response of Composite Overwrap Cylinders

Stress relaxation and creep of composite cylinders are investigated based on anisotropic viscoelasticity. The analysis accounts for ply-by-ply variation of material properties, ply orientations, and temperature gradients through the thickness of cylinders subjected to mechanical and thermal loads. Fiber reinforced composite materials generally illustrate extreme anisotropy in viscoelastic behavior. Accordingly, viscoelastic characteristics of composite cylinders are quite different from those of isotropic cylinders. Viscoelastic effects of the composite can result in a drastic change of stress and strain profiles in the cylinders over a period of time, which is critical for structural durability of composite cylinders. The developed analysis can be applied to composite pressure vessels and flywheels.