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Innovative digital, multi-parametric and predictable calculation model for the production of fibre reinforced 3D printed parts for aviation applications according to ISO9100

Periodic Reporting for period 1 - 3D-SE (Innovative digital, multi-parametric and predictable calculation model for the production of fibre reinforced 3D printed parts for aviation applications according to ISO9100)

Reporting period: 2019-12-16 to 2020-12-15

Aerospace Industry requires superior parts with special material characteristic such as high rigidity to mass ratio and a very good fatigue resistance as well as withstanding hydrothermal loads. Carbon-fibre reinforced plastic, or CFRP is the candidate that has the potential to offer all the mentioned requirement. Nowadays, aerospace industry has integrated more and more part made of CRFP into aircraft manufacturing. Unfortunately, the integration of CRFP is still limited due to the fact that the traditional CRFP manufacturing techniques have limitations when it comes to the model geometry beside it produces a lot of waste which rises intensively the parts cost resulting an increasing in the final product price. To overcome such limitation, researches proposed a new revolutionary technique known as 3D printing, this last has the potential to produce parts with high complexity which reduces the needs of assembly and limit the number of parts used. Moreover, it produces no waste, ensures the reproducibility and limited the human machine interaction. Thus, decrease the human errors and enhancing the part quality. The previously mention advantages motivated us to deliver the aerospace community a detail study on the quality of the printed CRFP parts (using the best CRFP printer in the market Markforge two) by quantify their thermomechanical characteristic. This will help understanding the global behaviors as well as defining the weak points in order to improve the techniques to fully satisfy the aerospace standardization. Hence, the phase of the project had an objective to fully characterized the printed CRFP specimens delivered by Markforged Mark Two printer owned by the company according to the ASTM standardization and to check if the delivered parts are conformed with aeronautic industry requirements. The phase was assigned a period of six months starting from June 2020. In order to achieve the cited objective, the associate was offered a training for the Eiger slicing software used by the printer and the CAD software Catia. After completing the trains, the associate engaged in a collaboration with Technische Universität Hamburg (TUHH) to perform the required characterization tests. Four types of standardization tests including tensile, interlaminar shear (ILSS), fatigue and dynamic mechanical thermal analysis (DMTA) have been performed for the mentioned purpose. The mechanical properties and their corresponding microstructure along with the fiber ratio effect have been investigated numerically and experimentally.
The 3D printed CRFP offers a promising advantage and can definitely upgrade the composite manufacturing to a way new level. It is indeed delivering a complex structure with the reproducibility insurance; it also reduces the timing between the design and the final product and limited the human machine interaction which results in minimization of errors, thus improve the product quality. Unfortunately, the CRFP 3D printing is not yet mature and need more research. The present project helped to point the process weakness and the to define the required improvement. The tests show that the mechanical properties of the printed CRFPs is less than the those produce by the traditional technique (< 50%). Moreover, the bonded between the carbon fiber and the plastique filament is weak and the process produces a high amount of voids (>5%).
Based on the deliver results the following points have been as a perspective for future project to improve the 3D printed CRFPs:

• In order to reduce the voids and strength the bounded between the plastique and the carbon fiber a consolidation process must be consider and an optimization study for the needed amount of temperature and pressure is crucial.
• To enhance the mechanical properties, the real amount of carbon fiber needs to be increase which required redesigning the printer and the corresponding software.
Microscopical image of the tested specimens with carbon fibre