the study of extremely high strain-rate single crystal plasticity
Developing a microscale split Hopkinson pressure bar for the study of extremely high strain-rate single crystal plasticity
Dr David Williamson
The strength of metals increases with deformation rate. Knowing by how much, and arguably more importantly why, are important considerations and questions in the fields of engineering and condensed matter physics.
A split Hopkinson pressure bar (SHPB) is an instrument that acts as a mechanical waveguide and is typically used to deform samples of materials at strain rates of order 10^3 per second. Miniaturization, of both the instrument and samples, is key to achieving higher strain rates. Using a so-called mini- SHPB we have had a great deal of success studying such materials as polycrystalline copper at strain rates of 10^4 to 10^5 per second.
Taking the next logical step, this experimental PhD project addresses the novel and technically challenging problem of developing and utilising a microscale split Hopkinson pressure bar for the study of single crystal and small grain size polycrystalline materials in uniaxial stress compression at extremely high strain-rates; in excess of 10^6 per second. This is a loading regime of importance in the development of physics-based materials models which is not directly accessible by other research techniques. The material to be studied will primarily be the bcc metal tantalum in single crystal form along specific loading axes (i.e., the principal crystal orientations) and the data will used for the development and validation of dislocation mobility and strain-hardening laws employed in mesoscale (grain-level) crystal plasticity simulations.
This project offers the opportunity to join a dynamic research group of twelve individuals and undertake cutting-edge research in the field of high-rate material physics: this project will push Hopkinson bar techniques to their physical limits.
The successful candidate can expect to present their research at international conferences, publish in leading journals, and develop their professional networks. In gaining experience in the design, delivery, and interpretation of experiments they will become a valued independent researcher.
This studentship is fully funded by AWE and is open to UK national students (full award; fees plus stipend).
Due to the nature of the work undertaken by AWE, University Personnel engaged in any Research Project shall normally be required to meet special nationality rules. To be eligible, the individual may be required to undergo security clearances and unless otherwise authorised should normally be a British Citizen as defined in the British Nationalities Act 1981.
The award covers the University course fees. The stipend (tax free maintenance grant) is set at the UKRI rate of £17,668 p.a. for the first year, and at least this amount for the remaining years.
Applicants should have (or expect to obtain by the start date) at least a good 2.1 degree in in Physics, Engineering or Materials Science and Metallurgy, and a keen interest in experimental science and the dynamic behaviour of materials.
The following skills are also highly desirable: ability to program in Python or similar, strong laboratory-based skills.
Please note that any offer of funding will be conditional on securing a place as a PhD student. Candidates will need to apply separately for admission through the University's Graduate Admissions application portal; this can be accessed via: https: // www. postgraduate.study.cam.ac.uk/courses/directory/pcphpdphy
Please indicate Dr David Williamson as the supervisor.
Additionally, please send your two-page CV and a motivation letter to Dr David Williamson ([email protected]) to arrive no later than 30 April 2023.
APPLICATION DEADLINE 30 April 2023.
START DATE 1 October 2023
Please quote reference KA35811 on your application and in any correspondence about this vacancy.
The University actively supports equality, diversity and inclusion and encourages applications from all sections of society.
The University has a responsibility to ensure that all employees are eligible to live and work in the UK.Department/Location
Department of Physics, Cavendish LaboratoryReference
10 March 2023Closing date
30 April 2023