ABSTRACT
In an engineering landscape increasingly focused on optimized design, lightweight materials, and multifunctional performance, accurately predicting the fatigue behaviour of composite materials under realistic service conditions is essential. Traditional approaches to fatigue analysis in Fibre Reinforced Polymers (FRP) often rely on simplified extrapolations of laboratory data or homogenized models that neglect the complex interactions between constituent materials and environmental influences. Moreover, these approaches typically fail to account for temperature variations. Such reductionist perspectives limit the ability to capture the coupled mechanical and thermal degradation mechanisms inherent to advanced materials.
This thesis proposes a unified numerical framework grounded in the Finite Element Method (FEM), integrating a phenomenological homogenization strategy, the Serial Parallel Rule of Mixtures Law (SP-RoM), with a High Cycle Fatigue (HCF) Constituive Law (CL). This approach enables the simultaneous representation of the distinct fatigue responses of fibres and matrix within layered composite laminates, accounting for variations in stacking sequence and fibre orientation. A key innovation is a calibration methodology that infers fatigue parameters at constituent level from experimental data at laminate scale, thus overcoming the challenges of direct testing of individual components.
Furthermore, the work presents a thermomechanically coupled fatigue model incorporating temperature dependent material properties and thermal expansion, generalizing classical fatigue life prediction curves to fluctuating and spatially varying temperature fields. To address the significant computational demands of fatigue simulations, an Advance in Time Strategy (AITS) Cycle Jump (CJ) is developed, enabling efficient simulation of long-term fatigue damage evolution without sacrificing accuracy. Validated against experimental benchmarks and literature data, the proposed methodology advances fatigue life prediction in composite materials by delivering a flexible, robust, and computationally efficient tool. Additionally, the fatigue formulation has been enhanced to capture complex thermomechanical effects. This work lays the foundation for future research on integrated modelling of fatigue and multiphysics deterioration phenomena in advanced composite structures.
PhD Advisors:
PHD CANDIDATE
Barbara Alcayde is a PhD candidate at CIMNE’s Aeronautical, Marine, Automotive and Energy Engineering research cluster. Her research focuses on computational modelling and structural analysis of composite materials, particularly in relation to fatigue behaviour and engineering applications, such as the automotive industry.