School of Physics and Astronomy

Strain Gradient Plasticity – Numerical Modelling And Implications For Fracture And Hydrogen Embrittlement

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23 January 2018

Time: 2:00 - 4:00pm
Speaker: Emilio Martínez Pañeda
Venue: G. O. Jones Building, Room 610

The speaker and his collaborators have been actively engaged in the investigation of gradient effects in fracture and damage. Strain gradient plasticity predictions reveal that GNDs close to the crack tip promote local strain hardening, leading to a much higher stress level relative to conventional plasticity. The analysis of stationary and propagating cracks shows that gradient plasticity models provide a sound rational basis to mechanistically interpret (i) cleavage in the presence of plasticity and (ii) hydrogen assisted cracking. Gradient-enhanced predictions proved to be particularly relevant in hydrogen embrittlement models due to the essential role that the hydrostatic stress has on both interface decohesion and hydrogen diffusion. Encouraging agreement with experimental data has been obtained by incorporating the GND effect in the modelling of hydrogen transport and environmentally assisted cracking. The promising results achieved have attracted the interest of industrial partners and technical standards organizations, ending with a scientific/engineering handshake a journey that began from fundamental micromechanics.

Short Bio

Emilio Martínez Pañeda works as Research Associate with Norman Fleck and Vikram Deshpande at the University of Cambridge. Before, he was an H.C. Ørsted Fellow at the Technical University of Denmark (DTU), where he conducted research in the group of Christian Niordson and Viggo Tvergaard. Emilio earned an Industrial Engineering (B.Eng+M.Eng) degree from the University of Oviedo (2011), an MSc degree in Structural Engineering from the University of Granada in (2012) and a PhD in Mechanics of Materials from the University of Oviedo (2013-2016). During his PhD, Martínez Pañeda conducted research under the supervision of Covadonga Betegón in the fields of mechanics of materials and computational solid mechanics. Emilio spent a large part of his PhD studies abroad, holding visiting scholar positions at the Technical University of Denmark (host: C. Niordson), the University of Luxembourg (host: S. Bordas), the University of California Santa Barbara (host: R. McMeeking) and the University of Cambridge (host: N. Fleck). His work on the mechanics of solids has been disseminated in numerous journal publications and has been recognized through several awards such as the Acta Materialia Student Award, the Springer PhD Thesis Prize or the Best PhD Thesis Award (Univ. Oviedo).