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June 2021: Latest PhD Opportunities with TWI

Mon, 07 June, 2021

PhD Vacancies in Cambridge with TWI Ltd and Lloyd's Register Foundation (LRF)

The industrial doctorate programme at TWI and managed by the National Structural Integrity Research Centre, is recruiting for two new full-time vacancies in Cambridge, United Kingdom.

Cambridge PhD Vacancies

  • Prediction of Step Wise Cracking due to hydrogen attack in steel vessels using finite element stress analysis and acoustic emission
  • Portable cold spray for repair of light metal components

PhD Studentship: Topic 1

Prediction of Step Wise Cracking due to Hydrogen attack in steel vessels using finite element stress analysis and acoustic emission

Background to topic: Why does industry need this research?

Corrosion has been prevalent in our lives since ancient times. It can be caused by many chemicals and substances such as hydrogen. In particular, process plants and pipelines are equipped with steel assets constituting a large portion of the entire plant infrastructure. These structures are exposed to various fluids providing conducive environments where free corrosive hydrogen atoms are released to the surfaces of the steel structure. Hydrogen Induced Cracking (HIC) is one form of Hydrogen damage that is omnipresent in sour production and has been the subject of a lot of research for decades.

Steel pipelines at process plant. Photo: Unsplash
Steel pipelines at process plant. Photo: Unsplash

The objective of the present project is to study the HIC progress in vessel steels used in the oil and gas industry. A Finite Element (FE) model will be developed to predict the stepwise cracking behaviour in these materials. An experimental program, involving Acoustic Emission (AE) monitoring and metallographic examination, will be specified and performed for validation of the FE model. The objective is to predict the Step Wise Cracking (SWHIC) growth based on the structural and material properties of the affected vessel using the FE model and the AE data.

Support for research project by TWI and LRF

Fullagar Technologies is a joint venture between TWI and Lloyds Register that was launched in 2018. The joint venture delivers innovative inspection systems, products and services using the very latest industry research from the National Structural Integrity Research Center (NSIRC). In a world of rapidly advancing digital developments, Fullagar Technologies provides the industry with trustworthy advanced inspection systems assurance and expertise in the areas of remote inspection, additive manufacturing and digital and data driven fabrication-Industry 4.0.

Funding for the doctorate programme

This project is funded by LRF and Brunel University London. The PhD studentship will provide successful Home/EU students with a minimum stipend of £16k/year and will cover the cost of tuition fees. Overseas applicants are welcome to apply, with total funding capped at £24k per year.



PhD Studentship: Topic 2

Portable cold spray for repair of light metal components

Background to topic: Why does industry need this research?

This proposed research project will investigate the emerging technology of portable cold spray as a means to economically repair light metal components. Work to date at TWI has shown that acceptable repairs can be successfully carried out using cold spray. However, the majority of this work has focused on developing high pressure cold spray, which must be performed using inert, high pressure gas within a dedicated, robotised, spray booth. As such, many repairs using this approach are not economically viable. 

Many aerospace components manufactured from light metals (such as aluminium and magnesium) suffer from environmental degradation during service due to wear, fatigue cracking, and/or corrosion. Often relatively minor damage cannot be accepted as it presents an unacceptable risk to safety. In such situations, components are often scrapped at high cost as no suitable repair method exists:

  • Heat input from weld based repairs result in unacceptable changes to microstructure and can lead to high residual stresses.
  • Blending out damage and filling with suitable polymers can be an option, but properties are poor and repairs often do not last long enough to be economically viable.  

Cold spray deposition is a solid-state thermal spray process that enables high quality repairs to be performed onto thermally sensitive materials. 

Feedstock powder is accelerated to supersonic velocities using a suitable propellant gas, such as nitrogen, helium, or air, causing the powder particles to impact onto the repair region at high velocity. Upon impact, particles undergo rapid and localised deformation, which can lead to the formation of metallic bonds. As these particles continuously bombard the surface and adhere to the substrate and each other, highly adherent coatings are formed. These coatings may be used to restore the dimensions of a worn or corroded part, or to impart property improvements, such as improved wear and corrosion resistance.

There are generally two main classifications of cold spray system:

  • Low pressure cold spray systems generally use compressed air or nitrogen gas as the propellant, and are small enough that they can be manipulated by hand. They are designed to be low cost, portable, and will run off a simple air compressor, making them easy to integrate into a workshop. The propellant gas may or may not be heated, and the gas pressure is typically <10 bar. As a result, particle velocity is lower than may be achieved with other systems, and so the feedstock powders are blended with a fine abrasive, such as aluminium oxide, which aids in particle adhesion and coating densification.
  • High pressure cold spray systems use high purity nitrogen or helium gas, at high pressure, and heated to a high temperature. Powder particles achieve a higher velocity than for a low pressure system, and so higher strength materials may be successfully deposited. However, the high temperatures and pressures generally make these systems large, and expensive to purchase and operate, and in many cases must be manipulated by an industrial robot.

Support for research project by LRF and Coventry University

A futuristic and advanced organisation, Coventry University has been recognised for providing high standards of postgraduate education and there focus on applied research AME is placed to be among the leaders of the fourth industrial revolution. The successful candidate will use all of this cutting-edge laser systems, and characterisation instrumentation.

Funding for doctorate programme

This industrial doctorate is funded by Coventry University, (LRF) and TWI. The funding covers the cost of Home/EU tuition fees and a standard tax-free RCUK stipend of £16K/year for three years. Non-EU students are welcome to apply, but the funding will only cover the cost of overseas tuition fees and the applicant need to self-fund their living cost for three years with total funding capped at £24k per year.

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