Submitted by Dr James Perry on Fri, 10/03/2023 - 15:36
The first of our funded PhD studentships for this year is now online; see link to the university's jobs page at the bottom of this article
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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.
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