Layer-by-Layer manufacturing of complex composites

Autoclave moulding is one of the commonly used processes by the aerospace industry to
manufacture low weight and high-performance composite parts. This manufacturing process
is a robust and well-established production method that offers satisfactory consolidation and
supresses defects formation, by applying high pressure and temperature. However, it involves
high capital and operation costs, as well as long cycle times, creating process bottlenecks.
That is why a cost-effective and more versatile process is in a high demand by manufacturers.
Vacuum-Bag-Only (VBO) consolidation is one of the available Out-of-Autoclave (OOA)
techniques that is under consideration to replace autoclave moulding using a new generation
of OOA prepregs. Even without the autoclave, an additional oven moulding step after the
material deposition, often performed via Automated Fibre Placement (AFP), is nevertheless
still necessary. There is hence a need for a novel method that tackles altogether the issues of
process rate, cost, energy use, and part performance.
The main goal of this PhD is to develop a new single-stage additive manufacturing process by
combining material placement, consolidation and curing of thermosetting composites.
To achieve this, several objectives must be considered:
Materials: Investigation of materials behaviour and selection of the suitable material for
layer-by-layer curing.

Manufacturing process: Development of a procedure and selection of suitable process
parameters, i.e. contact time, temperature, deposition speed and pressure.

Part quality: Investigation of the mechanical performance of the manufactured samples,
achieved via defect analysis and mechanical testing.

This project is supported by Rolls-Royce.

There are seven principal groups of beneficiaries for our new EPSRC Centre for Doctoral Training in Composites Science, Engineering, and Manufacturing.

1. Collaborating companies and organisations, who will gain privileged access to the unique concentration of research training and skills available within the CDT, through active participation in doctoral research projects. In the Centre we will explore innovative ideas, in conjunction with industrial partners, international partners, and other associated groups (CLF, Catapults). Showcase events, such as our annual conference, will offer opportunities to a much broader spectrum of potentially collaborating companies and other organisations. The supporting companies will benefit from cross-sector learning opportunities and

- specific innovations within their sponsored project that make a significant impact on the company;
- increased collaboration with academia;
- the development of blue-skies and long-term research at a lowered risk.

2. Early-stage investors, who will gain access to commercial opportunities that have been validated through proof-of-concept, through our NCC-led technology pull-through programme.

3. Academics within Bristol, across a diverse range of disciplines, and at other universities associated with Bristol through the Manufacturing Hub, will benefit from collaborative research and exploitation opportunities in our CDT. International visits made possible by the Centre will undoubtedly lead to a wider spectrum of research training and exploitation collaborations.

4. Research students will establish their reputations as part of the CDT. Training and experiences within the Centre will increase their awareness of wider and contextually important issues, such as IP identification, commercialisation opportunities, and engagement with the public.

5. Students at the partner universities (SFI - Limerick) and other institutions, who will benefit from the collaborative training environment through the technologically relevant feedback from commercial stakeholder organisations.

6. The University of Bristol will enhance their international profile in composites. In addition to the immediate gains such as high quality academic publications and conference presentations during the course of the Centre, the University gains from the collaboration with industry that will continue long after the participants graduate. This is shown by the

a) Follow-on research activities in related areas.
b) Willingness of past graduates to:

i) Act as advocates for the CDT through our alumni association;
ii) Participate in the Advisory Board of our proposed CDT;
iii) Act as mentors to current doctoral students.

7. Citizens of the UK. We have identified key fields in composites science, engineering and manufacturing technology which are of current strategic importance to the country and will demonstrate the route by which these fields will impact our lives. Our current CDTs have shown considerable impact on industry (e.g. Rolls Royce). Our proposed centre will continue to give this benefit. We have built activities into the CDT programme to develop wider competences of the students in:

a) Communication - presentations, videos, journal paper, workshops;
b) Exploitation - business plans and exploitation routes for research;
c) Public Understanding - science ambassador, schools events, website.