Delamination is a critical failure mode in layered composite materials, significantly impacting their structural integrity and durability [1]. Traditional modelling approaches for delamination, such as cohesive zone models, often become computationally prohibitive when dealing with composites with a large number of layers. To address this challenge, this study develops a homogenization-based approach to model delamination damage under static and cyclic loading conditions. The homogenization theory [2, 3] is formulated by representing the multi-layered composite as an equivalent continuum with virtual interfaces and virtual bulk layers. The methodology incorporates a stress-based approach to model damage initiation and progression, utilizing an exponential damage evolution. The homogenized model is calibrated and validated using high-fidelity numerical simulations and experimental data obtained from fatigue and quasi-static tests on laminated composites. Comparisons between the proposed homogenization approach and direct numerical simulations of delaminated composites demonstrate its accuracy and computational efficiency. The model successfully predicts the stiffness degradation, load-bearing capacity reduction, and progressive damage accumulation under cyclic loading conditions. The proposed theory [4, 5] has significant implications for the design and analysis of composite structures subjected to fatigue and static loads. This study paves the way for the development of advanced modelling tools for engineering applications in aerospace, automotive, and wind energy sectors, where layered composites are widely used. REFERENCES [1] Garg, N., Prusty, B.G., Ooi, E.T., Song, C., Pearce, G. and Phillips, A.W., 2020. Application of scaled boundary finite element method for delamination analysis of composite laminates using cohesive zone modelling. Composite Structures, 253, p.112773. [2] Barbu, L.G., Oller, S., Martinez, X. and Barbat, A.H., 2019. High-cycle fatigue constitutive model and a load-advance strategy for the analysis of unidirectional fiber reinforced composites subjected to longitudinal loads. Composite Structures, 220, pp.622-641. [3] Jiménez, S., Cornejo, A., Barbu, L.G., Oller, S. and Barbat, A.H., 2020. Analysis of the mock-up of a reactor containment building: Comparison with experimental results. Nuclear Engineering and Design, 359, p.110454. [4] Taherzadeh-Fard, A., Cornejo, A., Jiménez S., Barbu, L., 2023. A rule of mixtures approach