The effects of fiber angle and temperature on the distribution of long-term stress and creep strain for unidirectional multilayer composite cylinder

In this study, the distribution of radial and tangential creep strains and ratio of effective stress to internal pressure in a glass/vinyl ester thick-walled cylinder for long-term time period are studied. The constants of Schapery compatibility equations have been used for different temperatures and stresses. A symmetric multilayer composite long cylinder with 0, 45 and 90 fiber orientations has been modeled. The cylinder has been loaded by internal pressure and temperature difference. Also, the classical lamination theory has been applied for solving the equations. Viscoelastic model using Prandtl-Russ relations and Mendelson’s approximation method has been analyzed. In addition, the distribution of radial and tangential creep strains and effective stress in the wall thickness for different layouts and temperatures difference in 15 years has been drawn and analyzed. The results show that the ratio of effective stress to internal pressure increases. Further, with growing the temperature in the unidirectional multilayer with 0° and 90 ° fiber orientations, the radial and tangential creep strains increase. Also, in the unidirectional multilayer with 45° fiber orientation, the ratio of effective stress to internal pressure decreases with increasing the temperature differences. In addition, the absolute values of radial and tangential creep strains in the One of them is inner and the other in outerwalls increase and decrease, respectively.