Dr Siegkas is a Lecturer in the Engineering Department and is involved in teaching the Laboratory Analysis and Product Case Study, and Practical and Project Skills modules.
- PDRA: Imperial College London
- PDRA: University of Oxford
- DPhil: University of Oxford (Department of Engineering Science, Solid Mechanics group, Worcester College)
- GDL (Graduate Diploma in Law): BPP University London
- Eng-Dipl (5 year Degree): National Technical University of Athens (Mechanical Engineering-Aeronautics)
Dr Siegkas’ research within the field of solid mechanics includes developing and implementing experiment and modelling techniques related to material behavior and impact energy management in biomechanics and aerospace applications. Projects involved close collaboration with both industrial and academic partners of various fields.
Dr Siegkas’ DPhil within the solid mechanics group at the University of Oxford was focused on developing experiments and modeling techniques to characterise and model the static and dynamic performance of cellular materials for use as biocompatible bone implants and applications within the aerospace industry. Experiments involved mechanical testing at various strain rates and included the use of high speed photography, in-situ SEM, X-ray micro-tomography and image analysis.
Modelling included developing a method for virtually generating cellular material prototypes and then capturing their mechanical behavior at different scales thus providing a tool for virtual prototyping and characterisation based on application requirements. The foam geometries were generated in Matlab using a method based on Voronoi polyhedrals, that could either mimic geometrical features (e.g. pore size distribution) obtained by X-ray tomography analysis or generate new prototype geometries. The geometries were then subjected to uniaxial and multiaxial mechanical loading at the mesoscale level from which the macroscale properties were obtained. The virtual specimens were simulated using finite element techniques (Abaqus) at different strain rates. The project was partially funded by Rolls Royce, EPSRC and in collaboration with the IMI Canada.
Metal Alloys-Ballistics-Aerospace Components
During a postdoc at the engineering department at the University of Oxford, Dr Siegkas worked on the ballistic performance of granular materials (including Nickel at temperatures up to 800 degrees Celsius and Titanium alloys at room temperature) and jet engine components. The research was related to the aviation safety and ballistic energy absorption (i.e. jet engine fan blade off e.t.c.).
The projects were focused in designing experiments to generate data for material model calibration and validation or used for the development and optimisation of materials. The aim was to capture the material mechanisms involved in managing energy dissipation and related to application requirements. The work was done in collaboration with industrial partners (Rolls Royce, TIMET) and has received a departmental award under the University of Oxford departmental recognition scheme. Results dissemination is subject to publishing restrictions.
Traumatic Brain Injury
During a PDRA position at Imperial College London, Dr Siegkas worked on two projects related to understanding and preventing traumatic brain injury. The work involved implementing finite element models and extracting information as to regions of the brain that were mechanically affected by impact loading.
One of the projects was funded by the ‘’Welcome trust network of excellence’’ and was carried by a multidisciplinary team of experts from the fields of biology, neuroscience and solid mechanics. The second project was funded by the Welsh Government and was a collaboration between Imperial College and industrial partners (Dainese-AGV manufacturer of motorcycle helmets, Armougel manufacturer of liner add-on material). Dr Siegkas' role involved both experiments and computational modelling. Experiments included liner material characterisation (polymer), drop tower experiments on helmets (with and without added liner) and fitted on an instrumented head form. Modelling included using a head and brain model to extract information regarding potential injury and a full helmet-head form (Hybrid III) model of the drop tower tests aiming to extract information for further liner design and optimisation.
Sponsors and collaborators
Undertaken projects were funded and in collaboration with industrial, public and academic partners with expertise from multiple disciplines including: Rolls Royce, TIMET, McLaren, Hoganas, Division of Brain sciences Imperial College London and funding bodies such as EPSRC, Welsh Government and Welcome Trust Network of Excellence.
- Siegkas P, Petrinic N and Tagarielli VL. Measurements and micro-mechanical modelling of the response of sintered titanium foams, Journal of the Mechanical Behavior of Biomedical Materials, 2016, 57: 365-375
- Siegkas P, Tagarielli VL, Petrinic N and Lefebvre LP. The compressive response of a titanium foam at low and high strain rates, 2011, J Mater Sci, 46: 2741–2747
- Siegkas P, Tagarielli VL, Petrinic N and Lefebvre LP. Rate Dependence of the Compressive Response of Ti Foams. Metals (special issue), 2012, 2: 229-237.
- Simone F, Siegkas P, Barbieri E and Petrinic N. A new method for the generation of arbitrarily shaped 3D random polycrystalline domains J. Computational Mechanics, 2014
Dr Siegkas is the media, publicity and outreach representative for the department of Engineering. His research expertise includes porous-cellular materials, metal alloys, ballistics, aerospace components, protective equipment and traumatic brain injury (TBI).