Polymer matrix composites, such as carbon fibre-epoxy, constitute a core light-weighting technology across virtually all transport sectors (aerospace, automotive, marine), providing an important route to improved energy efficiency and sustainability. The complexity and limited quantitative understanding of fracture processes in such materials represents a key limitation to their exploitation. X-ray Computed tomography (XCT) provides a powerful 3D imaging tool to quantify microstructure and damage conditions in polymer matrix composites, particularly given: (a) spatial resolutions and range of sample sizes that can now be handled by different scanners, and (b) the potential for in situ monitoring of samples as they react and fail under load. As such, it has recently become possible to explicitly detect and quantify fracture processes in three dimensions (3D) down to the level of isolated single fibre breaks, whilst continuously loading a given coupon to failure. The Southampton XCT imaging labs (µ-VIS, www.muvis-org) have been world leading in such characterisation of composite failure via high resolution XCT methods, with a substantial publishing record in the field.
In this project, we will extend our expertise in in situ XCT imaging of composite fracture, focusing on volumetric (i.e. 3D) deformation and strain mapping via Digital Image Correlation (DVC). This essentially draws upon technology originally developed for windtunnels for automated tracking of smoke particles. We have recently demonstrated the principle of exploiting this technology by embedding ceramic nano-particles and/or thermoplastic phases within otherwise normal engineering composites, with the current project proposing the use of alternative markers such as carbon black for microscopic 3D strain mapping during fracture, thereby reducing the micromechanical influence of the markers on failure. Corresponding mapping of deformation/strains around damage sites has recently provided the first direct experimental visualisation of the transfer of mechanical load (‘shedding’) between broken and unbroken fibres that is fundamental to understanding catastrophic tensile failure in composites. This project will additionally develop finite element models that are both initialised and validated against XCT findings.
The project includes two Work Packages (WP)
WP1: Experimental comparison and optimisation of DVC strain mapping of composite fracture processes via carbon based and/or non carbon-based fiducials. This will utilise materials specifically made for the project via Mitsubishi (Japan), being imaged in a variety of laboratory and national X-ray imaging facilities.
WP2: Finite element assessment of fibre failure, interface sliding, separation and matrix deformation, and comparison to DVC findings.
In collaboration with Mitsubishi, the project draws on extensive capability in XCT imaging via the multi-million pound µ-VIS laboratory, and world class experience in composites analysis and manufacturing. The candidate requires a passion for detailed and precise experimental studies, and good computing competence (finite element modelling and 3D image processing). It would be suitable for engineering, materials science or physics graduates.
Supervisory Team: Ian Sinclair, Mark Spearing, Mark Mavrogordato
Tuition fees and stipend of £15,285 for UK students.
A very good undergraduate degree (at least a UK 2:1 honours degree, or its international equivalent).
Applications should be made online, select the academic session 2021/22 “PhD Engineering & Environment (Full time)” as the programme, and enter Ian Sinclair under the proposed supervisor.
Applications should include:
- Curriculum Vitae
- Two reference letters
- Degree Transcripts to date
Enquiries: [email protected]