This PhD will pioneer the use of highly efficient composite truss structures as reinforcement members for composite panels, with a particular focus on applications in the aerospace industries.

The patented wrapped tow reinforced (WrapToR) truss concept currently being researched at the University of Bristol has already been proven capable of producing low cost, consistent truss beam structures with a quick and simple fabrication process. An adapted filament winding technique allows continuous carbon fibre tow to be laid down as the shear elements, reducing the need for many individual members and automating much of the manufacturing. Previous work has already shown that these beams exhibit far superior stiffness and strength properties when compared to alternative structures of similar mass under a variety of loading conditions.

To date, research on this novel composite truss concept has focused on its use as beams and space frames, with the human powered helicopter Gamera II utilising the low mass and high stiffness properties of WrapToR trusses to break several FIA world records in human powered flight. The next step in developing this exciting technology is to integrate these naked beams and frames into closed panel structures to explore their use as reinforcement members. WrapToR reinforcement of skin panels has the potential to offer lower mass and higher stiffness and strength than alternative monolithic stiffening methods through exploitation of the excellent structural efficiency of trusses.

This project aims to use a multi-disciplinary approach to characterise and optimise the application of the WrapToR truss concept as a reinforcement member for structural panels, to demonstrate that WrapToR stiffened skin panels can improve the mechanical performance of aerospace vehicles such as rockets and reusable space planes, for a low mass budget. To achieve this aim, several objectives of increasing complexity have been planned out as shown below.

- Initially, a stiffened flat panel unit cell will be fabricated and tested to characterise its mechanical performance and validate models currently being developed.
- Secondly, validated models and optimisation algorithms will be used to design a larger, optimised flat panel structure to allow for comparative analysis of mechanical performance to alternative structures such as sandwich panels.
- Thirdly, the work will move from flat panel geometry to more complex curved geometry, with a curved stiffened panel demonstrator unit built and tested for stiffness and strength. Further development of models will be used for validation.
- Finally, a scaled down, curved stiffened structure will be designed, built, and tested for stiffness and strength to demonstrate the true potential of this novel technique. This scaled structure will replicate a relevant space or aerospace application to provide meaningful performance data that can be compared to current industry standards of panel stiffening.

Although this work will focus on aerospace vehicle structures, this concept would be suitable for a much wider range of industries and applications. From trains, planes, and rockets, to fuel tanks, ships, and wind turbine blades, where there is a need for mass efficiency in reinforcement, WrapToR stiffened skin panels can lead the way for the next generation of structural reinforcement.