Last week, MRG PhD students Kayleigh Nelson and Chris Triantafyllou went to Oxford, UK to present updates on their latest work at the 2nd International Workshop on Mechanistic Behaviour of HCP Alloys organised by HexMat!

The workshop took place at the beautiful surroundings of Pembroke College of the University of Oxford from the 16th-19th of September, attracting speakers from the UK, France and the US.

Organised by HexMat, the 5-year collaborative EPSRC programme focusing on hexagonal metals for the aerospace, defence and energy sectors, the workshop also welcomed speakers and attendees from industry, including Rolls-Royce and TIMET, as well as from organisations including the UK Atomic Energy Authority.

As the majority of talks focused on titanium, this was a great opportunity for us to present our latest work to a highly specialised audience, have stimulating and engaging discussions on some of the issues currently faced in industry, as well as get some advice for our own research.

Many thanks to Saira Naeem, Ben Britton and Fionn Dunne of Imperial College London for their wonderful work and effort in organising and running the workshop!

MSc student Martin Packham presented his summer project research work on carburisation of thin-walled pipes at high-temperature at the 28th International Workshop on Computational Mechanics of Materials (IWCMM) in Glasgow between the 10th and the 12th of September 2018. This research project, supervised by Dr Daniele Barbera, has been sponsored by EPSRC through a scholarship for students willing to start a PhD. The research done has yielded interesting results that will be used to further explore research directions in the field. In addition, the research work will be extended through a collaborating with the University of Strathclyde and results will be submitted for publication.
 
Within the same conference, Dr Daniele Barbera presented his work on unexpected plastic strain accumulation in the notched bar during high-temperature creep dwell. The audience has welcomed the results presented and new research collaborations have been discussed. The overall event was a great success and an excellent opportunity to disseminate the research done at MRG.

PhD student Ross Williams presented the latest updates on the research focused on computationally modelling inertia friction welding of nickel superalloys at the 6th European Conference on Computational Mechanics in Glasgow last week.

The research led by Dr Daniele Barbera, and for which Ross is a key contributor, has yielded notable progress over the last six months and the work presented included a numerical parametric study, whilst quantifying convergence of solutions as well as validating the robust nature of the work. You can read the full abstract here.

Coinciding with the 7th European Conference on Computational Fluid Dynamics, this year's conference attracted over 1,900 delegates and covered an extremely wide range of computational work and applications in over 120 sessions. Hosted jointly between the universities of Glasgow and Edinburgh, this is Europe's largest computational mechanics conference and was held in Scotland for the first time.

In addition to this, many other members of the MRG were involved in ECCM-ECFD 2018, including Dr Andrew McBride on the organising committee, as well as numerous other students involved as helpers. The event was a great success and we are looking forward to the next ECCM-ECFD conference in Paris in 2020!

MRG PhD student, Chris Triantafyllou, has been named the winner of the esteemed Whittle Reactionaries Prize 2018 by the Institution of Mechanical Engineers (IMechE).

The Whittle Reactionaries Prize Fund was established in 1998 by a group of Institution members in recognition of those engineers and others who had directly assisted Sir Frank Whittle in his company Power Jets Ltd during its pioneering and evolutionary work with reaction propulsion (jet propulsion) from the first experiments in 1937 to first operation use of Whittle Type W2B engines in an RAF Meteor aircraft in 1944.

Chris' work on implementing a scalable crystal plasticity model to simulate the cold-dwell fatigue behaviour of Ti64 billet was adjudicated by a panel of engineers chosen by the Combined Propulsion Technical Activity Committee of the IMechE and the Royal Aeronautical Society. The objective of the prize is to stimulate and encourage those in the early stages of their engineering career to continue to apply innovative and forward-looking thinking to aerospace propulsion problems that demonstrates:

• Technical excellence
• Originality and independent thinking
• High-quality presentation and effective communication

​​Chris added:

Dr Andrew McBride and PhD student Chris Triantafyllou travelled to Schöntal, Germany, last week to present the latest work on the use of specific experimental techniques and how these can be effectively used in conjunction with crystal plasticity simulations in the context of cold-dwell fatigue of titanium alloys.

The workshop organised by the Karlruhe Institute of Technology (KIT)  was held in the ex-monastery Kloster Schöntal and attracted leading figures in the field of dislocation modelling from all over the world with main focus on physical based continuum theories and simulations, but also featured comparisons with experimental work.

Chris gave a presentation of how crystal plasticity is aiding his research on cold-dwell fatigue, explained how the model was calibrated and what our goals are by analysing x-ray diffraction (Synchrotron) results in order to deepen our understanding of this behaviour, as well as improve the plasticity model.

Professor Paul Steinmann based at FAU in Erlangen, Germany and the University of Glasgow also gave a presentation on the current state and challenges in developing a physical based continuum theory of dislocations. Paul is the director of the Glasgow Computational Engineering Centre (GCEC) at the University of Glasgow and more information can be found here.

Last week Dr Euan Wielewski travelled to cold and snowy Ithaca with PhD students Kayleigh Nelson and Chris Triantafyllou to carry out experiments at the Cornell High Energy Synchrotron Source (CHESS).

Following up on Kayleigh's previous work, her experiments focused on the material's behaviour during strain jumps and Chris' experiments compared the fatigue behaviour with and without dwell episodes. These experiments marked the start of investigations on unidirectionally-rolled Ti64 for Chris and on cross-rolled Ti64 for Kayleigh.

The huge advantage of working in-situ at a synchrotron is that we were able to capture lattice strains through powder (x-ray) diffraction with an acquisition frequency of up to 10Hz. This is not only useful in providing a deeper understanding of the mechanical response at the grain level, but also generates information that can be used to significantly improve our computational models. Both Kayleigh and Chris will be resuming work using FEpX later next year, also developed at Cornell University.

Many thanks go to our collaborators from CHESS, Darren Pagan and Peter Ko, as well as Glenhead Engineering for their fantastic work with our millimetre-thick specimens!

MRG PhD students Kayleigh Nelson and Chris Triantafyllou attended the Aerospace Symposium 2017 organised by the University of Glasgow and had the chance to present two posters on their research.

The event which attracted over 80 delegates from industry and academia was focused on manufacturing for growth and featured interesting presentations from Airbus COO, Tom Williams, BAE Systems Head of Manufacturing and Materials Engineering, Andrew Schofield, and more.

Kayleigh's work focuses on the deformation of titanium alloys and how this differs between single- and dual-phase alloys. Chris has previously worked on cold-dwell fatigue and is currently investigation the effect of cross-rolling on notched fatigue behaviour. You can find out more about both projects here!

The Materials Research Group hosted a 2-day workshop at the University of Glasgow on 'Modelling the Micromechanics of Polycrystalline Materials'. The workshop took place on the 7-8th April 2016 and was sponsored by the Leverhulme Trust, the EPSRC and the University of Glasgow.

The goal of the workshop was to introduce researchers to the crystal plasticity finite element software package, FEpX, and a number of tools, including the virtual polycrystal generation package, Neper, and the crystal orientation calculation toolbox, ODFPF, that together constitute a complete capability for modelling polycrystalline solids.

The workshop was aimed at young researchers such as graduate students and post-doctoral associates who would like to integrate crystal-scale finite element modelling into their own research projects. Workshop attendees came from University of Oxford, Imperial College London, University of Manchester, University of Birmingham and University of Strathclyde.

The workshop consisted of several lectures as well as practical modelling experience, with the attendees executing FEpX simulations on a High Performance Computing (HPC) cluster at the University of Glasgow.

The workshop was led by Prof. Paul Dawson (Cornell University, USA), Dr Romain Quey ( Ecole des Mines de Saint-Etienne, France) and Matt Kasemer (Cornell University, USA).

More information about the software packages used in the workshop can be found here:

• FEpX - Crystal plasticity finite element software package
  
• Neper - Virtual polycrystal generation and meshing software package
• ODFPF - Crystal orientation calculations MATLAB toolbox

Euan and Kayleigh attended the International Workshop on 'Mechanistic Behaviour of HCP Alloys 2016', which was held at Pembroke College, Oxford, UK.

This workshop drew together industrial and academic experts from a variety of disciplines, including materials science and engineering, mechanical engineering, non destructive testing, and high rate deformation. Discussions focused on microstructure-performance property relationships and their impact on engineering components in industries such as aerospace, nuclear power, and transport. Read more about it here.

Euan presented his recent work on determining Ti-6Al-4V single crystal material parameters using a discrete spherical harmonic analysis of lattice strain pole figures from in situ mechanical testing at the Cornell High Energy Synchrotron Source and crystal plasticity finite element simulations. Euan also chaired a session on the high strain rate behaviour of HCP materials.

An article co-authored by Dr Andrew McBride, Mebratu Fenta & Daya Reddy has been published in Computer Methods in Applied Mechanics and Engineering.

An efficient time-stepping algorithm is proposed based on operator-splitting and the space-time discontinuous Galerkin finite element method for problems in the non-classical theory of thermoelasticity. The non-classical theory incorporates three models: the classical theory based on Fourier’s law of heat conduction resulting in a hyperbolic-parabolic coupled system, a non-classical theory of a fully-hyperbolic extension, and a combination of the two. The general problem is split into two contractive sub-problems, namely the mechanical phase and the thermal phase. Each sub-problem is discretized using the space-time dis- continuous Galerkin finite element method. The sub-problems are stable which then leads to unconditional stability of the global product algorithm. A number of numerical examples are presented to demonstrate the performance and capability of the method. 

You can access the full text via Science Direct by following the link below.