Advanced Continuous Tow Shearing for manufacturing defect-free complex composite parts
Lead Research Organisation:
University of Bristol
Department Name: Aerospace Engineering
Abstract
Current state of the art material deposition technology used to manufacture large composite parts has a limited capability in laying up on double curved surfaces. Fibre steering processes, such as automated tape laying (ATL) or automated fibre placement (AFP) are not capable of producing composite parts with complex geometry without inducing defects like tow gaps or overlaps. The minimum steering radius is dependent on the tape/tow width; Therefore, the steering radius requires to be kept as large as possible in the design phase, which significantly constrains the design flexibility and manufacturability.
The novel continuous tow shearing (CTS) technology, developed at the University of Bristol, allows to eliminate defects by steering fibres utilising in-plane shear deformation of the tape or tow. Its greatest advantage is that there is no coupling between the tape width and the minimum steering radius. Hence, even wide ATL grade tapes may be used allowing high material deposition rates.
However, this process requires to be improved for complex 3D layup, as it still does not eliminate defects when laying up on double curved surfaces. To date, triangular shaped resin pockets are induced by cutting individual tows during a 3-dimensional complex layup, which have a highly negative impact on the mechanical properties of the composite.
The aim of this PhD project is to advance the current CTS technology to enable manufacturing of defect-free 3D complex composite parts. In order to eliminate the tow gaps and overlaps that are inevitably produced in the current AFP process, a novel mechanism that can control the geometry of the tow/tape will be developed, which will eliminate geometry induced defects in production of 3D complex shapes. The Advanced CTS process with this novel mechanism will become an innovative solution to the quality problems of the current AFP process and significantly expand the design space of composite structures, allowing for ultra-high structural efficiency.
The novel continuous tow shearing (CTS) technology, developed at the University of Bristol, allows to eliminate defects by steering fibres utilising in-plane shear deformation of the tape or tow. Its greatest advantage is that there is no coupling between the tape width and the minimum steering radius. Hence, even wide ATL grade tapes may be used allowing high material deposition rates.
However, this process requires to be improved for complex 3D layup, as it still does not eliminate defects when laying up on double curved surfaces. To date, triangular shaped resin pockets are induced by cutting individual tows during a 3-dimensional complex layup, which have a highly negative impact on the mechanical properties of the composite.
The aim of this PhD project is to advance the current CTS technology to enable manufacturing of defect-free 3D complex composite parts. In order to eliminate the tow gaps and overlaps that are inevitably produced in the current AFP process, a novel mechanism that can control the geometry of the tow/tape will be developed, which will eliminate geometry induced defects in production of 3D complex shapes. The Advanced CTS process with this novel mechanism will become an innovative solution to the quality problems of the current AFP process and significantly expand the design space of composite structures, allowing for ultra-high structural efficiency.
Planned Impact
The chief impacts are twofold:
1. Supply of doctoral level engineers trained to the very highest standards in advanced composites. They will take up positions in industry as well as academia.
2. Development of next generation advanced composite materials and applications for wealth creation in the UK.
Other important impacts are:
3. Enhanced UK reputation as a world leading centre in advanced composites that attracts inward investment and export opportunity.
4. Attracting elite overseas students, enhancing the UK's global reputation for excellence in Advanced Composite materials and their applications and widening the pool of highly skilled labour for UK industry.
5. Engaging with local schools and media, to disseminate, enthuse and raise the profile of Engineering to school children and to the wider public.
1. Supply of doctoral level engineers trained to the very highest standards in advanced composites. They will take up positions in industry as well as academia.
2. Development of next generation advanced composite materials and applications for wealth creation in the UK.
Other important impacts are:
3. Enhanced UK reputation as a world leading centre in advanced composites that attracts inward investment and export opportunity.
4. Attracting elite overseas students, enhancing the UK's global reputation for excellence in Advanced Composite materials and their applications and widening the pool of highly skilled labour for UK industry.
5. Engaging with local schools and media, to disseminate, enthuse and raise the profile of Engineering to school children and to the wider public.
Organisations
| Description | The key aspect of this PhD work is to eliminate common automated fibre placement defects, such as fibre buckling, tow drops or tow overlaps to achieve ultra-high structural performance of a composite part by designing and implementing a novel tow width control (TWiC) concept. Various layups were produced and the layup accuracy and quality was assessed using newly-generated software codes, and the concept further improved. The TWiC concept is proven to be feasible and has great potential to improve the manufacture of composite parts. Mechanical testing of tow-width controlled coupons were carried out to understand the impact of the tow width control mechanism on the mechanical properties of the part. The results of an open-hole tensile test are compared to results of AFP manufactured coupons. (Analysis is still in progress) |
| Exploitation Route | Other mechanical tests, for instance compression tests might be carried out for tow-width-controlled specimens to obtain further understanding of TWiC on mechanical properties; At the moment, dry tow material is epoxy-resin impregnated and TWiC controlled within the machine. Prepreg material or the feasibility of the TWiC module in accordance to different resin systems could be investigated in the future, including thermoplastic resin systems. Also, initial tow widths may be varied and tested. Implementing the TWiC concept has the potential to highly improve the manufacturing process of composite parts in industry. |
| Sectors | Aerospace, Defence and Marine,Manufacturing, including Industrial Biotechology,Transport |