Model assessment of the lifetime of a composite overwrapped pressure vessel under creep conditions

Abstract

An approach has been developed to estimate the lifetime of a composite overwrapped pressure vessel under creep conditions. Creep tests of unidirectional composite material based on T1000 carbon fibers and epoxy resin were conducted at high temperatures. Experimental creep curves were obtained and the creep rate for each specimen was determined. A numerical analysis of creep of a composite overwrapped pressure vessel subjected to a constant pressure was carried out. Time-strain curves are obtained for each characteristic point in the composite shell. The strains range up to 12.5%. The curves of relaxation of tensile stress in a composite overwrapped pressure vessel are obtained. The stress gradually decreases from 926 to 564 MPa. The structure of the vessel considered remains stable without critical strains and stresses after 50 years of exploitation. Using the proposed modeling approach of a composite overwrapped pressure vessel, taking into account the effect of creep in the composite shell, it is possible to evaluate the lifetime of the structure.