16, November 2015

ESA Open Invitation To Tender AO8442
Open Date: 10/11/2015
Closing Date: 08/01/2016

Status: ISSUED
Reference Nr.: 15.1QM.16
Prog. Ref.: TRP
Budget Ref.: E/0901-01 – TRP
Tender Type: C
Price Range: 200-500 KEURO
Establishment: ESTEC
Directorate: Directorate of Technical & Quality Manag
Department: Product Assurance and Safety Department
Division: Materials & Components Technology Divisi
Contract Officer: van Hilten, Linda
Last Update Date: 10/11/2015
Update Reason: Tender issue

To develop Friction Welding processes so that external features such as attachment brackets can be easily welded to constructed frames without distorting or lowering the performance of the construction and with a significantly reduced environmental impact. Duringthe manufacturing of large structures such as launch vehicles, spacecraft, and propellant storage systems, it is often necessary toadd external features such as brackets during the manufacturing process. Depending on the material used for the structure, featuressuch as brackets can be attached using traditional techniques such as TIG welding. However during conventional fusion welding, there is always a danger that distortion can occur, or that the poor weldability of the material can result in a significant loss in mechanical performance or weld integrity. Moreover, fusion welding requires a significant amount of energy, consumables such as a covergasor flux, produces harmful emissions spatter, ultraviolet light and needs a significant amount of chemical cleaning agents. Recently,there have been significant advances made in the development of friction welding processes, whereby heat is generated through mechanical friction between a moving work piece and a stationary component, with the addition of a lateral force to plastically displaceand fuse the materials. There are essentially two types of friction welding process; Rotary Friction Welding (RFW) where the moving part rotates, against a stationary part, and Linear Friction Welding where the moving part oscillates against a stationary part. Both processes have a significant advantage over traditional welding processes in that the friction welding does not lead to the melting of the material, distortion is very low, and the techniques are environmentally friendly: they produce no spatter, no ultraviolet light and need a significantly reduced amount of energy as well as chemical cleaning agents. No consumables such as a covergas orflux are used, and no harmful emissions are created during welding. LFW allows no hydrogen take-up, no porosity, and no shrinkagevolume change reducing the need for repair and therefore keeping the manufacturing cycle to a minimum. However such processes have notyet been widely adopted by industry, with only limited applications being achieved, such as the manufacturing of BLISKS (Bladed Disk) for aero engines. In this activity the following tasks will be performed: 1) A short literature review will be performed to establish the type of external connections which are used on Launchers and Spacecraft systems, together with the current manufacturingmethodology. 2) The friction welding processes (RFW and LFW) will be developed so that reliable joints can be produced for theidentified type of connectors. Weld coupons will be produced and then subjected to a rigorous testing program to establish the performance ofthe weld. 3) The friction welding techniques and material combinations will be compared with equivalent designs joined byconventional techniques including cost, reliability, industrial efficiency and environmental friendliness aspects.

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