Development of a Damage Quantification Model for Composite Skin-Stiffener Structures

The development of a model-based approach for a damage severity assessment applied on a complex composite skin structure with stiffeners is presented in this paper. Earlier investigations on composite structures with stiffeners revealed that a vibration based structural health monitoring approach, employing the Modal Strain Energy Damage Index (MSE-DI) algorithm can detect and localise delaminations. The next step, performed in the presented part of the research, is to assess the severity of the damage. It is shown that combining results from a frequency based analysis and from a modal strain energy based analysis can enhance the quantification of the severity estimation. This conclusion was drawn by analysing the effect of small masses that were added at a specific location in to mimic a damage, but maintain reversibility of the damage. The use of a numerical model to create a virtual test space was found to be valuable for the interpretation of experimental data.