This paper proposes an analytical model capable of relating damage found on a composite plate to a given impactor characteristic (size and energy). The model addresses a gap in knowledge regarding the types of damages to be expected over the lifetime of a new generation of composite aircraft. The damage type and dimensions are estimated using a superposition of local indentation and global plate deflection. The analytical approach, validated by drop-weight experiments, uniquely uses the impact characteristics predicted from metal aircraft damages as inputs to model the impact event response for composite plates under the same impact event conditions. The case study demonstrates that impact data from metal aircraft can be used to anticipate damage for a composite aircraft. The results from the model indicate that of the impactors that previously damaged metal aircraft, 75% will cause surface dent damage, fibre breakage, or penetration. As an extension of the analytical model application, a risk assessment is conducted on the predicted impactors, incorporating maintenance cost as the primary indicator for event consequences. This assessment shows the risks the similar events pose on metal vs. a comparable composite structure and allows aircraft operators to anticipate and plan maintenance actions. ... Read more

In this thesis, a methodology is presented to predict impact damage on next-generation (composite) aircraft based on maintenance data of in-service (metal) aircraft. To achieve this conversion, an analytical model is developed to Model Impact Damage on Aircraft Structures (MIDAS) for composite (-C ) and metal (-M ) aircraft. The model characterizes impact threats based on damage dimensions in two steps. First, for a given specific threat an impact event is approximated, and the corresponding damage (i.e. the permanent dent) is estimated. Second, the analytical model is reverse engineered to deduce the impact threat characteristics from the permanent damage. MIDAS-M implements a new transition region between the local and global deformation modes based on penetration limits, while composite variant (MIDAS-C) provides a novel approach for the permanent indentation in the post fiber breakage region. ... Read more