Making lightweight additive manufacturing work for heavily regulated aerospace applications
The aerospace industry demands quality at every stage - underpinned by stringent requirements for precision, safety, and reliability. With passenger traffic doubling and pressure to reduce ecological impact on the planet greater than ever, manufacturers in the space and aerospace industry must meet the demands of 21st century aviation, with particular emphasis on creating lightweight parts. There are no short cuts, however, and manufacturers are constantly exploring new ways of designing and building more aircrafts which are lighter, in a faster timeframe, whilst achieving heavily regulated certification before any aircraft can take flight.
The requirement for lightweight parts drives the need to manufacture components for aircraft differently – for example, employing advanced composites or new processes such as additive manufacturing (AM). However, any new design brings new challenges for certification and aerospace manufacturers often address design certification hurdles with homegrown workflows, but this is not a small undertaking and can involve a significant amount of time – sometimes months – and that is without having to address any mistakes on the way. Navigating through aerospace standards to determine which test is required to achieve certification is a laborious, time-consuming exercise. As advances in engineering and production technologies make it increasingly easy to innovate, the need to streamline certification activities is a given.
Challenges of AM
In responding to the challenges, aerospace manufacturers are increasingly using AM to make lightweight parts from different materials, including advanced composites, that could not be produced using traditional processes. Utilising AM minimises the use of materials, so there is less waste and reduces energy consumption as part of the manufacturing process.
Leveraging AM to design a lightweight part requires a generative design approach that enables engineers to completely rethink existing structures without feeling constrained by preconceived ideas of what a part and consolidated parts should look like. By creating a simulation of the part virtually, it reduces the number of physical trials tryouts without consuming any raw materials. It also enables the engineer to quickly adapt the process of manufacture until a process is achieved that works.
Generative design has evolved from simply magicking up thousands of possible CAD designs, to acting as an engineering “co-pilot” to quickly design lightweight parts that give the required engineering performance based on the part’s loads, design envelope and strength or stiffness goals.
The performance benefits of generative design can be significant. One example is the work undertaken by Hexagon for Tesat-Spacecom GmbH & Co. KG and Trumpf on a satellite bracket, where lightweight construction is particularly important, as every extra kilogram generates high costs for transportation into space. Hexagon technology was used to create a new highly complex design which enables maximum lightweight construction and is perfectly adapted and designed to the operational requirements. By re-engineering the bracket geometry through generative design, they reduced the weight by 55% and increased its stiffness by 79%. For high precision applications like this, process simulation plays an important role in compensating for the thermal-mechanical issues introduced during powder bed fusion (PBF).
Creating a virtual print, such as a simulation of the manufacturing process, can reduce the number of physical tryouts, so there is no requirement for the use of raw materials. Simply print the design on the computer and if the design fails, make changes until the process works. Safran, for example, uses Simufact Additive to virtually develop and validate the AM process for metal parts it produces with PPBF, reducing physical iterations.
Composites add further lightweighting and innovation potential. Engineers just need the digital tools that give them the answers they need to make sure the parts will perform as intended – which is a little more complex for anisotropic materials, where the very microstructure that makes the material outperform a metal also makes it very challenging to understand the performance of the part in its intended application.
Thanks to a partnership between Hexagon and Stratasys, an innovative leader of 3D printing and advanced manufacturing services, engineers can now access detailed models of its aerospace-approved materials and the toolpaths of its aerospace-ready printers, so design engineers can use it to simulate how parts printed from these materials will perform.
With computer-aided engineering (CAE) tools, engineering teams can reliably replace machined metal components with lightweight parts that fully leverage the properties of these reinforced polymers, while avoiding costly overengineering and material use.
Using rigorously validated material behaviour simulations such as these, aerospace manufacturers now stand to benefit from unique insights into the performance of its materials and bring the benefits of polymer 3D printing into the highly regulated world of aerospace. For most aerospace applications, there is a requirement for more of a connection with the data and the engineers themselves that are involved in the design phase, to accelerate the design process, deliver more optimal end results and ultimately achieve flight certification.
The horizon for aerospace AM
The application of AM to make highly optimised components such as engine parts to improve sustainability is growing. For most aerospace applications, AM teams need much more of a connection with the data and the engineers that are involved in the design phase, so they can validate engineering performance and ultimately achieve flight certification sooner.
For example, it’s now possible to connect all steps of design for manufacturing (DfAM) together so that engineers can optimise a part topology and work in its generation of support structures that these ‘bionic’ geometries require, process tweaks and compensation distortion together at the same time.
However, to make the step change in aerospace usage and flight readiness, manufacturers need to connect more data and people, upstream and downstream and left and right, to validate that design for manufacturing and that it will deliver a valid flight-worthy part and with the process assurance and process repeatability required.
New collaborative digital reality platforms like ‘Nexus’ will enable engineering teams to extend the cohesive developments that DfAM solutions are bringing to the sector with “building blocks” for finite element analysis and process analytics and traceability, so manufacturers can perform engineering validation and refine processes faster to get them right the first time. This therefore saves valuable time and resources while achieving accreditation faster for sustainable aviation and new mobility concepts.
Mathieu Perennou, is the Additive Manufacturing Solutions Director at Hexagon Manufacturing Intelligence.