10:50   Session 11: Digital engineering II Chair: Yuval Freed 10:50 20 mins Development of AI to diagnose depth direction defect in continuous fiber 3D printed CFRP composite based on laser ultrasonic testing Hyeon-Gyu Park, Kyu-Jin Lee, Jung-Ryul Lee Abstract: ABSTRACT Since 3D printed composites are capable of arbitrary three-dimensional shape design and have good mechanical properties, many studies have been conducted as parts materials for the aerospace industry [1][2]. However, during the long-term process of the 3D printing composite, the offset of the nozzle changes finely or defects caused by twisting have a problem of degrading mechanical properties. In addition, there is also a problem that is subjective and takes a lot of time when evaluating internal defects. Therefore, to address these problems, we aim to develop sophisticated defect diagnosis AI that can detect the location of depth direction defects. In this study, pulse-echo laser ultrasound examination techniques and six-degree-of-freedom robotic arm are used to examine real structures of complex shapes. The pulse-echo laser ultrasound examination technique is a method in which the excitation laser excites the structure of interest, and then the laser Doppler Vibrometer (LDV) receives it and performs a non-destructive examination. Six-degree-of-freedom robotic arm corrects the curvature so that the pulse-echo laser is vertically incident on any three-dimensional shape. Continuous fiber 3D printer was used to make specimens for learning data, Onyx with nylon-based carbon short fiber and carbon continuous fiber filaments were used as materials, and lamination was performed through the Material Extrusion method. The C-Scan image visualized using the pulse-echo laser ultrasonic was binarized by matching the visible result by minimum intensity projection through X-Ray Microscope, and then labeled for AI learning data. Deep ensemble CNN was modelled to extract advanced features by considering Time series and spatial information simultaneously. The final network was optimized through hyperparameter tuning, and the reliability of diagnostic AI was verified through 5-Fold validation. Through this study, defects on real-structure specimens of continuous fiber 3D printed CFRP composites were visualized through defect diagnosis AI, and defect detection target accuracy for test specimens was achieved. This study is expected to give many advantages such as establishing a process strategy by presenting the location of the defect beyond simply determining the presence or absence of the defect. [1] N Shahrubudin et al. Procedia Manufacturing. 35:1286-1296, 2019 [2] Sanei, S.H.R.; Popescu, D. 3D-Printed Carbon Fiber Reinforced Polymer Composites: A Systematic Review. J. Compos. Sci. 2020, 4, 98. https://doi.org/10.3390/jcs4030098 11:10 20 mins Application of continuum damage mechanics for in-service real fatigue cracking scenarios Ismael Rivero Arevalo, Jorge Gonzalez Rubio, Rodrigo Ruiz Santos, Javier Gómez-Escalonilla Martin, Sonia Blayac, Daniel Barroso Vloedgraven, Rebeca Martínez Perez Abstract: F&DT evaluation for aeronautical structures is a complex process able to produce robust designs and ensure high safety standards. Nevertheless fatigue cracking events are still happening in any aircraft fleet, in most of the cases due to an interaction of several causes that cannot be properly combined in the standard F&DT evaluations. The evaluation and correlation of in-service findings is essential to ensure that root cause is identified and adequate corrective actions are taken. However this is not an easy task as these events are usually associated with complex structural and material behaviours that are difficult to be properly predicted under certain conditions by current F&DT certification methods. This paper presents an Airbus real practical application in the context of an in-service cracking scenario using more sophisticated state-of-the-art F&DT prediction methods techniques combining a highly refined detailed finite element model with a fatigue damage model based on the Continuum Damage Mechanics framework. Details of the overall process followed as a result of an in service crack finding will be provided. This process includes a full damage correlation against a specific subcomponent test and in service experience as part of the Continuous Airworthiness verification, validation and acceptance criteria. 11:30 20 mins Structural integrity as enabler towards sustainability in aviation Ligeia Paletti Abstract: Aviation is undergoing an epochal transition to ensure air mobility will continue to provide its value to society, while at the same time stop impacting the climate, by zeroing the emissions of all types of greenhouse gases and pollutants. To achieve this, technological developments focus on propulsive solutions. Not only such propulsive solutions will impact the design of aircraft, conventional designs also need to be reevaluated to achieve a sustainable aviation. The implementation of structural integrity in aircraft design and certification is not yet fully effective in the conventional aircraft lifecycle, and it will need significant research in relation to the new designs. Currently, this limits the beneficial impact of structural integrity on aircraft structures and materials, and its potential contribution to sustainability. The knowledge, practices and tools embedded in aeronautical structural integrity are identified as a stringent need in other sectors. This means that structural integrity can be not only beneficial for the aviation sector itself, but it could have a broader impact on other sectors. Unfortunately, within the aeronautical structural integrity community, the connection between sustainability and structural integrity is not fully visible. The technical language used in the structural integrity publications also create a barrier in terms of accessibility of the results of the structural integrity research and their value. This creates a disconnect between different research fields, but also with younger generations of researchers. This paper wants to put aeronautical structural integrity in relation to the field of sustainability, to show how structural integrity is a fundamental enabler of sustainability in aviation; then the paper provides a view of how bringing structural integrity at the forefront of aircraft design could enable the design of even more sustainable aircraft structures. Last an overview of what structural integrity practices could be beneficial in other applications than aviation is given, together with recommendations on how to engage with sustainability researchers in aviation and in another fields. 11:50 20 mins Enabling the journey towards Condition Based Maintenance for Airframe Julien Baris, Eugene O'Higgins, Melanie DUCOFFE, Derk Daverschot Abstract: Airlines are constantly looking for solutions both to reduce their operational costs and increase aircraft availability. Currently, maintenance programs are based on conservative design assumptions, which aim to cover a high variety of usage in the fleet and ensure safety. As every aircraft is operated differently and each flight performed is unique (due to changing weather conditions, payload, routes etc.), there is a high potential benefit in moving away from a “one size fits all” approach to more efficient and optimised structural maintenance requirements tailored to individual aircraft. Several initiatives have been undertaken to incrementally optimise maintenance programs with the ultimate objective to offer full Condition Based Maintenance and enable operators to: - Reduce direct maintenance costs by adjusting maintenance requirements based on ‘actual’ aircraft usage. - Reduce the unknowns and conservatism inherent in design assumptions. - Ensure that safety of aircraft operations is maintained at the highest level. - Increase the residual value of aircraft or aircraft parts. The rapid development of Digital Twins and the growing performance of Artificial Intelligence could be key enablers for such optimisation. A huge volume of in-service ‘big data’ obtained from flight-by-flight recordings and aircraft sensors has to be processed, leading to new challenges in the capability to exploit all of the available information. With a large number of flights being performed every day, it is not practical to process such volumes of data with classical approaches (e.g. finite element analysis etc.). Therefore, alternatives to the existing models used for certification have to be exploited, such as for instance (but not limited to): - Improvements of existing methodologies. - Support from Artificial Intelligence. - Enhanced computational capabilities. - … Nonetheless, any solutions implemented must always guarantee the highest level of safety. 12:10 20 mins A-10 implementing prognostics with the digital thread Martin Raming, Hazen Sedgwick, Luciano Smith, Paul Clark Abstract: Digital transformation is trending across the United States Air Force (USAF) to optimize modern and legacy aircraft lifecycle management. A desired output of the digital thread is to provide accurate and efficient prognostic tools to forecast the future structural health of a defense system. Legacy aircraft, like the A-10, face additional challenges in implementing the digital thread compared to modern counterparts; however, legacy aircraft would benefit further and immediately from digital thread predictive capabilities. This research will investigate the route the USAF’s A-10 aircraft structural integrity program (ASIP) takes to implement a complete digital thread solution for digital engineering, specifically regarding prognostic tools. It is necessary to have high data quality and informative data models to make accurate predictions. Additionally, the data type captured must also meet the requirements of data models. This research found that specific data types needed were often fragmented and must be amalgamated before analysis could be performed. The acculturation of maintenance groups to digital transformation and engineering rigor is another requirement identified for implementing the digital thread and is often overlooked. While these requirements presented many challenges, setbacks, and lessons learned, A-10 has built the foundation needed to begin implementing prognostic maintenance tools. Maintenance data is digitally captured with digital thread software that provides an interactive 3D environment to tie metadata to coordinates. In addition, A-10 has piloted smart tools to take full credit for repair operations in damage tolerance predictions. Analyzed maintenance data is then integrated with additional PLM and SLM systems to provide a holistic interpretation of the health of the active fleet. While in its infancy, integrating these systems will eventually lead to a complete digital twin. A significant takeaway from this study is that implementing the digital thread for prognostics is not trivial; ensuring successful operations of these systems and that captured data is complete and verified required multiple additions of full-time personnel to A-10’s technical division. However, for A-10, the ability to proactively maintain an aging fleet comes with many benefits, including a significant reduction in sustainment costs, better management of risk, and improved aircraft availability.

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