Modal strain energy-based structural health monitoring validation on rib stiffened composite panels

Structural Health Monitoring (SHM) techniques are emerging more and more in aerospace composite structure applications. Validation of the SHM techniques is one of the issues to be addressed yet. Moreover, cost-efficient and reproducible ways to compare SHM methods can be attractive for researchers and end users. NLR has recently developed ways for automated production of rib-stiffened composite panels using an Automated Fibre Placement (AFP) machine. Without human interference and a fully automated manufacturing process, multiple panels can be cost-effectively laid-up with limited quality variation. In this paper, Modal Strain Energy Damage Index (MSE-DI) method is applied on two impact-damaged panels manufactured in this new way. The results show that the panels have slightly deviating natural frequencies even though the C-scan revealed no major quality variation. Secondly, the presence of the impact damage can be successfully detected by the MSE-DI algorithm, but the localization was inaccurate, contradicting the expectations. This is attributed to the specific characteristics of the panel and indicates a dependency of the performance of algorithms on structure to which they are applied. Future work will include a further exploration of this dependency.