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The paper describes a system that it is able of monitoring the health state of a composite structure in real time. The hardware of the system consists of a wire of strain sensors connected to a control unit. The software of the system elaborates the strain data and in real time is able to detect the presence of an eventual damage of the structures monitored with the strain sensors. The algorithm requires as input only the strains of the monitored structured measured on real time, i.e. those strains coming from the deformations of the composite structure due to the working loads. The health monitoring system does not require any additional device to interrogate the structure as often used in the literature, instead it is based on a self-learning procedure. The strain data acquired when the structure is healthy are used to set up the correlations between the strain in different positions of structure by means of neural network. Once the correlations between the strains in different position have been set up, these correlations act as a fingerprint of the healthy structure. In case of damage the correlation between the strains in the position of the structure near the damage will change due to the change of the stiffness of the structure caused by the damage. The developed software is able to recognize the change of the transfer function between the strains and consequently is able to detect the damage.

Blends based on the semicrystalline Poly(ether ether ketone) – PEEK and the amorphous Poly(ether imide) – PEI have been widely investigated for their outstanding mechanical, thermal and chemical-physical properties. The conformation of the PEI monomer affects the miscibility of the blends. Although the large interest in high demanding lightweight applications, foams from PEEK/PEI blend have not been considered until recently. The aim of this work was to prepare foams from PEEK/PEI miscible blends by using supercritical carbon dioxide. The role of blend composition on the density and the morphological parameters of the resulting foams was investigated.