Impact Damage Identification on Composite Structures

Impacts are an important hazard for composite structures in aerospace applications. Various methods are developed for detection of impacts, which can be done in geometrically more complex structures. A number of challenges prohibits a further analysis of impacts, like the energy associated and the required action to avoid immediate or delayed catastrophic failure. The challenges include both the algorithms to reconstruct the energy, and the sensors capturing the response. In the current research, an impact identification algorithm is developed, using both Piezoelectric Wafer Active Sensors and optical sensors. Initially, drop weight impacts of various energies are applied on a homogeneous thin aluminium plate and on a quasi-isotropic thin carbon fibre reinforced plastic plate. The objective is to compare the performance of the various sensor methods and explore the abilities to reconstruct not only the location but also the impact energy. In a second stage, impacts are applied to a geometrically complex, full-scale aircraft horizontal tail plain component. Parallel to the experimental work, numerical models are developed to assist the reconstruction. The first results show that the optical fibres have potential, as the signal to noise ratio is high. However, the signals are not yet of sufficient quality to proceed to force or energy reconstruction and are below the performance known from piezoelectric sensors in a pitch catch setting.