Prognostics and Health Management (PHM) is a multidisci-plinary field aiming at maintaining physical systems in their optimal functioning conditions. The system under study is assumed to be monitored by sensors from which are obtained measurements reflecting the system’s health state. A health index (HI) is estimated to feed a data-driven PHM solution developed to predict the remaining useful life (RUL). In this paper, the values taken by an HI are assumed imprecise (IHI). An IHI is interpreted as a planar figure called polygon and a case-based reasoning (CBR) approach is adapted to estimate the RUL. This adaptation makes use of computational geom-etry tools in order to estimate the nearest cases to a given testing instance. The proposed algorithm called RULCLIP-PER is assessed and compared on datasets generated by the NASA’s turbofan simulator (C-MAPSS) including the four turbofan testing datasets and the two testing datasets of the PHM’08 data challenge. These datasets represent 1360 test-ing instances and cover different realistic and difficult cases considering operating conditions and fault modes with un-known characteristics. The problem of feature selection, health index estimation, RUL fusion and ensembles are also tackled. The proposed algorithm is shown to be efficient with few pa-rameter tuning on all datasets. 1.

The use of composite structures in the space domain has increased significantly over the past years owing to its high strength to weight ratio. Because of the criticality and huge amount of money associated with these missions, there is an urgent requirement to monitor the structural integrity and its degradation by novel SHM techniques. In this paper we use ultrasonic guided wave technology and study the different possibilities of embedding piezoelectric sensors (PZT) into the carbon composites made by filament winding. We demonstrate the sensing capabilities of our developed sensor system to damages which can arise due to any accidental low-energy impact. A series of lab test was conducted on composite coupons to inspect the ability of PZT sensors to detect individual damages with high probability based on their distance from the impact location. The results show that PZT sensors are very promising in detecting all the damages caused by impacts with varying energies and can be a possible answer to needs of the structural health monitoring and non-destructive evaluation of advanced space structures. 1.