2023-06-27 09:30:31
Hexagon is a Swedish industrial group offering technological solutions for simulating and validating the behavior of innovative materials making up industrial parts, particularly for aeronautics.
Hexagon is the market leader in digital reality solutions for businesses. The Swedish company thus offers its customers the possibility of making the best use of all the data generated by their activities, with the aim of improving processes, efficiency, productivity and quality.
Mathieu Perennou, Director of strategy and development of additive manufacturing activity at Hexagon, explained to Engineering Techniques the solutions developed by the company within the framework of the additive manufacturing of composite materials for aeronautics, in particular within the framework of the development of eVTOL.
Engineering Techniques: Can you present to us the technologies developed by Hexagon in relation to the development of the eVTOL, with regard to the behavior of the composite materials used for this aircraft?
Mathieu Perennou : The certification process for new aircraft is an area in which Hexagon has been involved for decades. The development of a new aircraft is very often accompanied by the development of new and sophisticated technology which must be tested and certified. Thus, many “firsts” have passed through our doors over the past 50 years: the first jet aircraft, the first delta-wing fighter aircraft, the first supersonic aircraft and the first two-stage four-engine jumbo jet… All have been certified using our software solutions. The emerging eVTOL industry is no exception. Most of these new eVTOL aircraft companies are considering all-new combinations of tiltrotors, tiltwings, all-composite fuselages, electric flight control systems, and rechargeable electric battery systems, as well as new methods of manufacturing that have never been seen before in the world of aviation. Consequently, engineers need to rely increasingly on simulation tools to model, test and validate these new technological solutions both in terms of designs and in terms of materials and manufacturing processes, in order to bring these new technologies at the levels necessary for the generalization of the eVTOL industry.
More specifically, aerospace (and new eVTOL aircraft) is one of the industries pushing the boundaries of materials innovation for greener transportation.
In terms of validating the behavior of the structures of new eVTOL aircraft, Hexagon is responding to growing interest with its new version of MSC Nastran implicit nonlinear (SOL400) in the design of composites and lighter aeronautical structures. Another challenge solved by this release for engine designers and eVTOLs is the ability to set individual RPMs for multiple rotors and reference any rotor. This makes MSC Nastran Rotor Dynamics more accurate as each motor can have its own speeds and characteristics, making it easier to perform sensitivity studies.
At the level of the composite materials themselves, we have developed a software solution (Digimat) which makes it possible to model these new materials, as well as to test and qualify them virtually, in order on the one hand to reduce the development time of new materials, and on the other hand to obtain relevant numerical models and material maps which will be used as input data for structural calculations as well as the simulation of manufacturing processes.
What are the obstacles today linked to the additive manufacturing of materials intended to equip the aircraft of tomorrow?
One of the obstacles to the development of additive manufacturing in the field of tomorrow’s aircraft is the need for materials that meet the following aeronautical criteria: more economical, with sufficient fire resistance and higher mechanical and thermal performance.
Inevitably, for an industry with strong regulatory constraints such as aeronautics, the development of new materials and the validation of the behavior of these materials and the need for certification of the parts with the highest criticality as well as the whole design/process/material/printer hinder the adoption of new materials and new manufacturing processes linked to them.
Another point closely linked to the certification of parts remains the subject of the evaluation and assurance of the quality of the parts and the material produced. The lack of experience on the material quality of the parts obtained in AM, this unknown generating a risk on the real (and not theoretical) performance of the manufactured parts, necessarily generates challenges of qualification and therefore of adoption.
On the product design side, the relative lack of maturity of additive manufacturing processes is still significant today, as well as the lack of specific knowledge in design for additive manufacturing (AM), what is commonly called “Design for Additive Manufacturing” (DfAM).
The lack of a complete range of manufacturing, from design rules (DfAM), through the repeatability of the manufacturing process and the digital chain to part controls today limits the development of these new solutions in the framework of an Industry 4.0 approach.
A final point is the relative immaturity of machines in terms of reliability, which generates a systematic need for quality control of manufactured parts (dimensional and material quality control) during production.
What does 3D printing of materials change in the design of tomorrow’s aircraft? What are the advantages ?
First of all, the reduction of the mass of the parts. This mass reduction takes place at 3 levels:
The freedom of design offered by AM allows the manufacture of optimized shapes by replacing metal parts with composite or an assembly of several parts with a single part. Replacement of metal parts with polymer/composite parts. The reduction of wasted material through the additive approach to the manufacturing process which offers unrivaled “Buy2Fly” ratios.
Then, 3D printing makes it possible to reduce costs, in particular for parts in small and medium series, the cost structure of which is currently largely impacted by tooling. The reduction in cycle time (for example by switching to direct manufacturing without tools) and a supply chain flexibility (with on-demand production) are clear advantages for manufacturers.
The freedom of design and the tool-free aspect of the process also allow unlimited personalization/customization of parts as well as the addition of functionalities.
Finally, more specifically at the level of composite materials, the possibility of optimizing the performance of the part by playing on the orientation of the fibers for the filled materials, controlled by the deposition strategies used, offers manufacturers new possibilities on the design some products.
What are the main materials used in additive manufacturing in aeronautics today?
In terms of polymer and composite materials, the following materials all meet fire resistance constraints and are regularly used by additive manufacturing in aeronautics:
Ultem 9085 which offers excellent resistance to heat and chemicals in addition to being tolerant to fire, smoke and toxicity and has finally benefited from a qualification campaign with the NCAMP. Certain polyamides such as PA2241FR in a powder bed (economical, flame-retardant polyamide 12 with a high recycling rate) or the increasingly frequent use of materials from the PAEK family such as PEEK or PEKK, known for their low flammability and their excellent mechanical, chemical and wear resistance.
Interview by Pierre Thouverez
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