Periodic Reporting for period 1 - UltraSafe (Advanced modelling of ultrasonic wave interaction with damage for enhanced failure identification technologies in industrial composite structures)
Reporting period: 2018-02-25 to 2020-02-24
Modern industrial structures are increasingly made of composite layered materials due to their well-known benefits. The usage of composite structures however implies a greater range of possible structural failure modes for which the structure has to be frequently and thoroughly inspected. For instance, approximately 27% of an average modern aircraft’s lifecycle cost is spent on inspection and repair . The use of ‘offline’ structural inspection techniques currently leads to a massive reduction of the product’s availability and significant financial losses for the operator. Ultrasonic Guided Waves (UGWs) have exhibited strong potential for detecting damage signatures in composite structures, however understanding UGW interaction with realistic nonlinear damage scenarios is still a fundamental technological and scientific issue which remains unresolved. UltraSafe will bring together an ER being expert in ‘linear and nonlinear wave propagation’ and a host institution carrying leading academic know-how in ‘damage modelling in layered composites' in order to develop the next generation of ‘online’, fast and robust damage identification tools for industrial composite structures.
O1) Develop a comprehensive set of FE modelled composite structural segments containing structural damage of a range of types and sizes: Monolithic as well as layered segments have been modelled with the aid of computational FE tools. UNOTT’s TexGen software is planned to be employed towards the end of the project. Researchers have already attempted that route, however the involved computational cost was significantly limiting that direction of research.
O2) Develop a generic and robust wave/FE numerical tool able to accurately model elastic wave interaction with the damaged structural segments obtained through O1: Wave transmission, reflection and conversion has been computed in a broadband frequency range (0.1-1MHz). Complex scattering effects can be computed through the delivered scheme.
O3) Experimentally validate the developed numerical tools. At least six composite structures (of beam and panel geometries) will be manufactured through the equipment available within ANOVA and UNOTT’s Composites Group. Three different types of damage will be implemented in the manufactured specimens. The predictions of the numerical models will be assessed against the measurements to validate the UltraSafe’s computational scheme.
O4)Deliver an inverse computational scheme for identifying structural damage through its nonlinear UGW signature. A Bayesian network scheme will be formulated in order to represent the probabilistic relationships between the measured damage signatures and the actual damage size and type to be identified.
UltraSafe brings together an ER being expert in ‘linear and nonlinear wave-based evaluation techniques’ and a host institution carrying leading academic know-how in ‘damage modelling and identification in composite structures’ in order to develop the next generation of online, fast and robust damage identification tools for industrial composite structures. The derived tools are expected to provide a blueprint for condition-based maintenance for aerospace structures, which can radically decrease maintenance costs, increase aircraft availability with simultaneous advantages for passengers worldwide.