Hybrid continuum shell-solid modelling for effective digital twinning of composite scarf repairs

This study presents a focused review and implementation of FEA methodologies for modelling scarf repairs in carbon fibre–epoxy laminates within a digital‑twinning context. A hybrid continuum shell-solid FEA strategy is proposed, in which continuum shell elements are used to represent the composite laminates and solid elements are employed to capture the adhesive layer response. The proposed approach is validated against benchmark simulations, demonstrating high fidelity in stress distribution and damage prediction while achieving a substantial reduction in computational cost. The resulting solver provides a computationally efficient and accurate foundation for integration into broader digital‑twinning frameworks for composite repair assessment.