Multiaxial fatigue modeling of continuous fiber-reinforced polymers using a critical plane approach

Abstract

Abstract: This paper presents extension of the application of a damage parameter recently shown to successfully model multiaxial fatigue behavior of short fiber-reinforced composites to continuous fiber composite materials. The authors conducted an experimental campaign on the fatigue life of carbon fiber-reinforced polymer composite (CFRP), taking into consideration several load ratios (R) as well as in-phase and out-of-phase loadings. The study focused on modeling fatigue damage initiation by incorporating the shear stress range and maximum normal stress. The analysis of stiffness degradation confirmed that most of the fatigue life was governed by damage onset and the propagation of small cracks. The observed damage was primarily associated with matrix-fiber debonding. This approach was verified with the literature's experimental data for glass fiber-reinforced polymer (GFRP) and the authors' experimental data for CFRP. Although those materials exhibit a similar fracture nature, they differ significantly in many aspects, i.e., fiber orientation, layup configuration, constituent materials and stiffness properties. The correlation of the stress-based damage parameter shows good agreement with both the authors’ and the literature experimental data, with coefficient of correlation (r) 0.84 and 0.89, respectively. The critical plane concept was also applied to estimate fatigue life, revealing that the long-life fatigue strength corresponds to approximately 25% of the ultimate tensile strength (UTS) for cylindrical specimens. Based on this relationship, the S–N curve for fatigue prediction can be constructed using only the UTS. Highlights: (Table presented.)

Publication Title

Archives of Civil and Mechanical Engineering

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