Performance evaluation of repaired composites under dynamic loading for structural applications

Applications are invited for a self-funded, 3-year full-time or 6-year part time PhD project.

The PhD will be based in the School of Mechanical and Design Engineering and will be supervised by Dr Khaled Giasin. 

The work on this project could involve:

• Creating an artificial damage in composite structures through dynamic loading at various temperatures.  
• Removing the damaged area using abrasive water jet cutting process (this requires optimisation of the machining process for optimum cut quality). 
• Repairing the damaged region in the composite structure by patching technique (adding new layers of composite materials to replace the damaged region).
• Test the repaired composite under static and dynamic loading at various temperatures and compare its performance to that observed from the original pre-damaged structure. 
• Analyse and optimise factors which could influence the performance of repaired composite structures such as manufacturing technique.  

Project description

Composite structures are used in many aerospace applications thanks to their excellent strength to weight ratio compared to metallic alloys. However, when composites are damaged, they are usually discarded and end up in landfills due to the difficulty in recycling them. An alternative is to attempt to repair the damaged composite structure through accurate machining and patching strategies. The damaged area is removed using a machining process followed by applying patches of same or matching composite material to replace the removed area (damaged area). The removal of the damaged area is performed using conventional machining techniques such as milling. However, this process can be costly and poses health hazards (respiratory problems) due to the dust generated during the machining process. Moreover, the cutting tools tend to wear out quickly due to the abrasive nature of the fibres. Moreover, the contact between the cutting tool and the composite material induces large amounts of heat which adversely affect the dimensional accuracy of the composite structure. An alternative is to use non-conventional machining processes such as abrasive water jet cutting (AWJC) to avoid the previously mentioned concerns. AWJC process have developed significantly in the past few decades which enables it to be used for cutting composite structures. It can also provide better solution for removing the damaged regions in the composite structures with minimal costs, health concerns and acceptable accuracy. Therefore, using AWJC in the repair process of composite structures might have positive impact on its performance which could encourage the adoption of repairing instead of disposing the damaged composite structures. This project aims to investigate the performance of repaired composite structures under static and dynamic loading conditions. The aim is to study the performance of the composite under various impact loadings at different temperatures (cryogenic and up to the epoxy/resin operating range) and compare that to the performance of the original composite structure. The project is of great importance and a steppingstone in the path of saving landfills from composite materials and maintaining a cleaner environment. A life cycle analysis will be carried out to evaluate and compare the effectiveness of repaired composite structure against pre damaged and disposed ones. 

General admissions criteria

You'll need a good first degree from an internationally recognised university or a Master’s degree in an appropriate subject. In exceptional cases, we may consider equivalent professional experience and/or qualifications. English language proficiency at a minimum of IELTS band 6.5 with no component score below 6.0.

Specific candidate requirements

You should be self-motivated, independent and a quick learner. Experience in mechanical testing and characterisation of composite materials is desirable. Knowledge of the following is desirable: 

• fundamentals of composite materials subjected to static and dynamic loading
• different composite manufacturing techniques (hand layup, autoclave, compression moulding).  
• abrasive water jet cutting process and machining principles in general. 
• statistical analysis and use of statistical software is desirable.
• lifecycle analysis process and techniques is desirable. 

How to Apply

We encourage you to contact Dr Khaled Giasin ([Email Address Removed]) to discuss your interest before you apply, quoting the project code below.

When you are ready to apply, please follow the 'Apply now' link on the Mechanical and Design Engineering PhD subject area page and select the link for the relevant intake. Make sure you submit a personal statement, proof of your degrees and grades, details of two referees, proof of your English language proficiency and an up-to-date CV. Our ‘How to Apply’ page offers further guidance on the PhD application process. 

When applying please quote project code:SMDE6131023