DEVELOPMENT OF A LIFETIME MODEL OF COMPOSITE STRUCTURES IN STATIC AND FATIGUE

Abstract

The objective of this project is to develop an analytical model that predicts the lifetime of multilayer tubular structures. These structures are made with long glass fibers and an epoxy matrix. These tubes contain six layers with an orientation angle of 55°. The developed model simulates the mechanical response of a cylindrical composite structure under different types of loading, such as pure internal pressure, internal pressure with background effects, tension, and cyclic fatigue. Tensile and cyclic traction tests were performed on composite tubes. Tensile tests allow us to estimate ultimate stress to failure. Cyclic reaction tests allow us to estimate the remaining potential. The developed model allows us to estimate the number of cycles to failure of the composite tube. Cyclic tensile tests allow us to determine the remaining potential of composite tubes. The results show that when composite tubes are exposed to cyclic loading, the number of cycles induces a significant change in the shape of the tensile stress-strain curve and a decrease in the elastic modulus. Additionally, cyclic loading tests are conducted at multiple stress amplitudes (40%, 60%, and 80% of the ultimate tensile strength) to evaluate the material's fatigue life and damage progression at different load levels. These tests quantify the relationship between stress amplitude and the number of cycles to failure.