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Details of Grant 

EPSRC Reference: EP/N021975/1
Title: Towards Tailored Composite Bonded Repairs (BONDPAIR)
Principal Investigator: Katnam, Dr K
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department: Mechanical Aerospace and Civil Eng
Organisation: University of Manchester, The
Scheme: First Grant - Revised 2009
Starts: 01 June 2016 Ends: 31 May 2017 Value (£): 99,306
EPSRC Research Topic Classifications:
Manufact. Enterprise Ops& Mgmt Materials testing & eng.
EPSRC Industrial Sector Classifications:
Aerospace, Defence and Marine
Related Grants:
Panel History:
Panel DatePanel NameOutcome
25 Nov 2015 Engineering Prioritisation Panel Meeting 25th and 26th November 2015 Announced
Summary on Grant Application Form
Advanced composites are currently being used in aircraft structures (primary and secondary components) to a significant extent (e.g. 50% by weight in Boeing 787, Airbus A350 and Bombardier C-Series). For these new generation of aircraft structures with large composite components, the existing repair technology must be significantly improved to fabricate robust, reliable and certifiable repairs for restoring damaged (e.g. impact loads) primary structural components. It is important to note that primary aircraft structural components are critical to aircraft structural integrity and safety. The primary components are highly loaded and relatively thick (ranging from ~3 mm to ~25 mm) with several laminae having different fibre orientations, and thus require advanced repair design and fabrication techniques to restore the original structural/operational conditions. In this regard, current repair design and fabrication approaches need to be significantly improved for repairing primary composite aircraft structures.

As mechanically fastened composite repairs are not ideal for polymer composite structures because of the stress concentrations induced by fasteners, bonded scarf repairs, which can provide high joint efficiency and aerodynamic surface finish, offer opportunity to improve composite repair methodology and thus have greater potential for aircraft repairs. The extent of material damage is often uncertain and depends on the source/nature of damage. The amount of material that needs to be removed from the parent component for a scarf repair not only depends on the amount of material damaged but also the geometrical parameters (e.g. patch shape, scarf angle) of the patch designed. A significant amount of undamaged material around the damaged region needs to be machined in order to achieve the designed patch geometry. In addition, the amount of undamaged material removed can have an adverse effect on a component that is designed to take high stresses. To minimize the removal of undamaged material from the component, the design of scarf repairs should be tailored for a given repair condition. On the other hand, novel fabrication techniques need to be developed to achieve complex patch geometries (e.g. accurate machining of parent laminate, curing of a mating patch).

In this context, the proposed research is focused towards tailored composite bonded repairs to primary composite structures using non-conventional scarf patch geometries. The project aims to (a) develop a novel infusion-based repair methodology to fabricate scarf repairs using easy-to-store materials (carbon fibre fabric, thermoplastic veils) without pre-preg and film adhesives, (b) minimize the amount of undamaged material from the parent component by incorporating non-conventional patch geometries for enhancing parent-patch interface stress distribution, and (c) characterising failure behaviour of tailored scarf repairs and comparing with conventional scarf repairs. The ambition of this research project is to develop scientific pathways that will enable future repair technologies, especially tailored for primary composite components in aircraft structures.
Key Findings
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Potential use in non-academic contexts
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Date Materialised
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Organisation Website: http://www.man.ac.uk