Finite element modeling of viscoelastic creep behavior and transverse cracking in fiber-reinforced composite materials

Fiber-reinforced composites are essential in the aerospace industry, highlighting the need for an in-depth understanding of their durability. This study introduces a novel approach that integrates viscoelasticity and damage evolution based on continuum damage mechanics, employing finite element analysis. The method utilizes an anisotropic viscoelastic constitutive law to examine creep behavior under constant stress, decomposing stresses into equilibrium and non-equilibrium components. Moreover, it integrates a transverse crack damage variable associated with crack density. After solving stiffness equations, a detailed analysis of transverse crack propagation is conducted. This technique was applied to creep tests on carbon fiber-reinforced plastics and 3D woven ceramic matrix composites, resulting in strain and crack density profiles. The numerical simulations successfully reproduced experimental outcomes. The developed method offers a comprehensive tool for analyzing transverse crack propagation under viscoelastic creep conditions through finite element analysis, significantly enhancing design considerations by incorporating aspects of long-term durability.