Application of a composite damage model for the justification of large aircraft structures

The pursuit of sustainable aviation is driving the integration of advanced composite materials into primary aircraft structures, enabling substantial weight reductions and gains in fuel efficiency. Recent programs increasingly integrate composites into slender, stiffened structures-such as wings. These designs exploit post-buckling regimes, where failure is governed by complex damage initiation and propagation within the buckled skins and stiffeners. Consequently, predictive models must capture both global structural instability and local damage mechanics, while accounting for specific geometric and laminate details. This presents a significant challenge for model validation, which is a cornerstone of the aircraft certification process. This article addresses this challenge by first analyzing the key requirements for composite damage models to be deemed certifiable. It then proposes a validation framework designed to rigorously assess a model's predictive accuracy across the entire design domain and under all relevant loading conditions. The framework is demonstrated through a detailed case study on a representative composite wing panel. Results confirm that the validated damage model can reliably predict the sequence of damage events, aligning closely with experimental observations.