Case Study - Wind Tunnel Model
A Challenging Project
The model was to enable them to test various configurations of future aircraft concept, and the most complex component, the 'ejector' was designed to simulate the effect of the engines. By integrating more functions into this component, it was possible to reduce the total size of the model and enable more representative aerodynamic conditions in the wind-tunnel, for the given power available.
The goal was to package several separate functions within a single part, enabling ARA to simulate the mass flow effect of the engines while also collecting the static pressure data which would enable them to evaluate the effect on the airflow at the intake and outlet of the model engines.
Designed for Success
The key to the success of this project was the close collaboration between the Engineering teams in ARA and APWORKS. For this kind of complex part to be manufacturable, it is important to design with the entire manufacturing process flow in mind, including printing, non-destructive inspection, machining and assembly.
The combination of ARA's undertanding of the design intent and assembly requirements, coupled with APWORKS' expertise in the manufacturing process, working together as a team, ensured success from the start.
ARA have specialist machining capabilities which are well suited to the precision machining required for the part, so the cooperation involved APWORKS delivering the inspected 'blank' part to ARA for final machining.
APWORKS produced the various parts for this project using their EOS M400 systems which utilise the Laser Beam Powder Bed Fusion (LB-PBF) process. This process spreads thin layers of metal powder and selectively melts it using a directed laser beam. This process results in parts with excellent mechanical properties, and thanks to the layer by layer approach it is possible to produce complex geometries which would be impossible using conventional casting and machining processes. However, this process does also have it's limitations, which is why ARA involved APWORKS from the concept design stage to ensure that the design would be feasible and cost effective to manufacture.
In this project some of the parts were produced in titanium alloy Ti6Al4V, and some of the parts were produced in Scalmalloy. APWORKS has tested thousands of test specimens which give a high level of confidence in the material properties which are used for design. This is critical in applications such as this where the parts are subjected to high pressure and there are safety regulations which need to be met.
To ensure that the part was dimensionally accurate for machining, APWORKS used 3D-scanning technology. This enabled ARA to best-fit the machining datums based on the actual dimensional accuracy of the part features.
In order to ensure that the part was leak-tight and defect free, APWORKS performed a CT-scan, which was also compared with the in-process monitoring images from the build process. Combined with our statistical process control and traveller tensile specimen testing, this gave us a high degree of confidence in the quality of the part.
In order to comply with pressure vessel safety standards the part was successfully leak tested and proof-pressure tested by ARA after final machining.
Overall in the project a number of complex components were produced and successfully used to support the groundbreaking research being performed by ARA and partners in the SUBLIME project. The use of Additive Manufacturing (AM) enabled much more complex parts while also shrinking the size of components and reducing the number of parts and assembly operations required. The fact that this kind of complex project could be delivered in only 7 weeks shows very well the benefits of AM for functional prototyping and test.
APWORKS would like to thank ARA for the friendly cooperation in this project, and all the partners in the Sublime project for this opportunity to share a great example of the benefits of Additive Manufacturing.
Some of the AM components produced in the SUBLIME project, from left to right:
Single Nacelle with combined Rake and Ejector (Titanium), Pipe Ducting (Titanium), Dual Nacelles with Rakes (Titanium)