The aerospace industry currently has a need for lightweight, complex composite structures to make their way into operational use. Changes in the regulatory landscape and demands for reduced emissions, coupled with the need to optimize Revenue Passenger Kilometers (RPK), have driven research efforts into lighter and more efficient aircraft designs. A key approach to reducing emissions is minimizing weight: by reducing weight, fuel usage drops, leading to a reduction in overall emissions. This requires that traditional materials such as steel, aluminium, and even titanium be replaced with lighter, high-performance materials.
High Performance Thermoplastics Composites (HPTPCs) are an excellent solution to the issues of recyclability, light weight, high performance, and reparability. HPTPCs offer compelling advantages over metal components: improved working life, more design freedom, lower weight (and thus reduced fuel consumption), and longer service intervals. Thermoplastic composites have several very specific advantages: they can be directly joined using welding techniques, and due to their toughness, there is less risk for catastrophic damage in case of an impact, and damage will grow at much smaller rates in the laminate structure. The use of thermoplastic composites can reduce manufacturing times by as much as 20-30% as compared with metals or thermoset composites, due to their potential for automated production, and the aforementioned welding capabilities.
Welding has the unique feature that there is a continuous, homogeneous presence of polymer over the joint interface. In fact, in a proper welded joint, there is no joint area to be identified when inspected under a microscope. Next to that, welding is not critical for surface preparation, mixing quality or curing parameters, as adhesive bonding is. This makes welded joints fundamentally different with respect to certification requirements, and basically much easier to certify. This allowed the qualification and certification of welded primary aircraft structures without the use of “chicken rivets”. Still, damage arrest features could further improve the damage tolerance performance of welded joints. Considering the reformable nature of thermoplastics, there is potential for different approaches in the development of disbond arrest techniques for these materials. The main aim of the TORNADO project is to develop innovative disbond arrest features (DAFs) for long thermoplastic welded joints.
This main aim is composed of four Key Objectives (KO), which will make the overall TORNADO project realistic and achievable within the proposed 24-month timeframe, as follows:
- KO1: Implement novel DAF technologies in compliance with the Topic Manager’s specifications
The TORNADO project will implement and structurally validate two different DAF technologies at the coupon and demonstrator level. The DAF technologies will be designed from the ground up to comply with the Topic Manager’s design, performance, and implementation specifications, but will be based on background knowledge of three partners and existing feasibility study.
- KO2: Fully validate the DAF technologies in accordance with industry standards
The final TRL level of the DAF technologies will be TRL 5, and all validation will be performed
by RESCOLL, which is an accredited aerospace testing laboratory.
- KO3: Design and implement digital tools for DAF technologies
UPAT will develop and implement new digital tools for the design and virtual testing of DAF
technologies, based upon the three technologies evaluated in the project.
- KO4: Validate the DAF technology process at the industrial scale
KVE will develop and validate a robotic end effector for DAF installation, available for licensed application at the Topic Manager’s facilities or for demonstration in the SAM|XL fieldlab during the recently granted Penelope Factory of the Future project.
The TORNADO consortium is fully equipped to undertake all tasks proposed within the project, and includes partners fully equipped to develop welding equipment and perform the welding tasks on the industrial scale (KVE). Testing will be performed by RESCOLL, an SME with extensive experience in aerospace testing, and which is certified for testing by major vendors and organizations such as AIRBUS, SAFRAN, Gulfstream, and NADCAP. Simulation/modeling and digital tools will be produced by UPAT for the DAF performance and by KVE for the thermal simulation/modeling of the induction heating.