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. Experimental validation of the model is conducted using a high-tensioned composite overwrapped on a steel cylinder. The creep and stress relaxation response of composite is accelerated at elevated temperatures, then characterized and compared to the model simulation. Fiber reinforced composite materials generally illustrate extreme anisotropy in viscoelastic behavior. 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, gun barrels, and flywheels design of life prediction.
Creep and stress relaxation behavior for natural cellulose crystal of wood cell wall under uniaxial tensile stress in the fiber direction