Three types of defects were selected based on occurrence rates, processes concerned, knock-down on properties, detectability, the expected gain if reduced, the repairability and the amount of data. The defects that are selected are porosity, waviness and gaps/overlaps of tows. Together, they cover more than 75% of the defects typically found in the production of aircraft structural parts.
The numerical description and integration in finite element models as well as sensitivity analysis were completed. This allowed further on to compare and validate the numerical results with representative experimental data of the defects.
Based on data available and description of the defect in terms of size, location and detection thresholds, the representation of the defect at an RVE level, as well as its inclusion in the structural analysis framework, were completed. For porosity, this was done at an elementary level as we can treat it as a change in local material properties, for gaps and waviness, the effect of the defect is intimately linked to its orientation and its geometry. A valid workflow to include these defects was thought up and tested.
Work was carried out to address the presence of defects at the scale of a composite panel. The challenge is to identify how to integrate the defect as well as choose the right distribution of parameters for the defect. The consortium aimed for a possible inclusion of the defect in the structural model without having to fundamentally modify the representation of the reference structure. This will allow to include the effect of the defect on the distribution of forces. The workflow and model implementation tools that were created allow to cover a large scope scenarios.
To extend the impact of the project, further validation with respect data can be sought in the near future. The project reached its main objectives and both the specimen virtual allowable evaluation tool, integrated in the Digimat suite and the probabilistic evaluation chain are major deliverables that will rapidly be exploited through activities at the Topic Manager's premises and through each of the participant's activities. New research project activities are being prepared to further build on the experience gained and reach new levels of technology readiness level. While dissemination activities during the last year of the project were limited due to COVID restriction (conferences, fairs), the partners hope to be able to communicate on project results after the project ending.
