REDISH is following a systematic down-selection strategy based on a high-fidelity numerical approach validated by experimental testing. The workflow of this innovative methodology is represented in Figure 2. An initial pool of shielding solutions identified as promising and that meet the design requirements defined by the TM is down-selected in stepwise processes that systematically evaluate the solutions at two major structural levels of increasing complexity: laminate level and structural/component level.
In the first step of the down-selection process (laminate level), materials screening for impact performance was carried by ranking the initial pool of promising solutions according to ‘performance’, ‘evaluation easiness’ and ‘implementation easiness’ weighted indicators, wherein the first one was evaluated by means of analytical/empirical formulations available in the literature. This resulted in the identification of more than 30 solutions, and derivations thereof, for the next evaluation step which already relied on high-fidelity finite element analyses. For these, the necessary material constitutive models were either developed in-house or were available in the finite element software package Abaqus/Explicit, selected in agreement with the Topic Manager (TM) to be used in the project. This performance evaluation resulted in a higher-fidelity ranking of more than 20 evaluated solutions and a second down-selection step to 14 solutions that were actually manufactured, and are being experimentally evaluated in the framework of another Clean Sky 2 project (ELEMENT, grant agreement nr. 715873). The experimental results at this level were used to yet another performance ranking on the 14 tested solutions, and to validate and improve the numerical models. The third down-selection step, based on experimental results, resulted in the identification of 5 families of impact shielding configurations that are being evaluated at component/structural level stage (Level 2).
The numerical analyses at Level 2 are being performed by means of a Computational Mechanics approach wherein mostly shell finite elements are used and the Continuum Damage Models, being intrinsically demanding in terms of the required computational resources, will be implemented in a ‘lean’ form, such that computational mechanics simulation at component/structure level is efficiently carried out. In particular, the modelling of the essential phenomenology associated with the behaviour of composites under impact and crushing loads is ensured. The modelling of the failure modes not associated with these load types is simplified if and when this will lead to a relevant reduction in the required computational resources. The high-fidelity numerical evaluation of the performance of the solutions will guide the process of manufacturing and experimental testing of structural panels in Level 2. This will lead to the final selection step in which the final solution to be applied on CROR engine debris impact shielding will be selected. The experimental results will also be used to validate the numerical simulations at component level.
