ELFT HÍRADÓ

[Zsolt Kovacs <kovacszs AT caesar.elte.hu>]

ELTE Fizikai Intézet, Anyagfizikai Tanszék TANSZÉKI SZEMINÁRIUM
!!!!! FIGYELEM A SZOKÁSOSTÓL ELTÉRŐ SZEMINÁRIUMI ALKALOM !!!!! !!!!! 
KEZDÉS KEDD DÉLUTÁN 14.00-kor !!!!! 2017. május 30., kedd, 14:00-kor 
ELTE, Pázmány Péter sétány 1/A alatti épületében, 4.52 (Sas Elemér) 
teremben Peter Derlet (Paul Scherrer Institut, Villigen, Svájc) Critical 
stress statistics in a simplified dislocation dynamic model Abstract: A 
simplified dislocation dynamics model developed to study 
micro-plasticity and the transition to yield is presented [1]. Here, an 
explicit dislocation population represents the mobile dislocation 
content and an internal shear- stress field represents a static 
mean-field description of the immobile dislocation content. The model 
exhibits scale-free avalanche phenomenon, with an exponent and 
scaling-collapse for the strain-burst magnitude distribution equal to 
that of a mean-field de-pinning transition. Using the approach of 
extreme-value-statistics, the current talk will focus on the statistics 
of the critical stresses at which the discrete plastic events occur [2], 
and how the statistics change as the yield transition is approached. Via 
a linear stability analysis, it is found that the locally stable 
dislocation structure prior to a plastic event is related, via a fold 
catastrophe, to the emerging structural instability [3]. The talk 
concludes discussing about the possible generality and applicability of 
the results to more realistic descriptions of dislocation mediated 
plasticity. [1] P. M. Derlet and R. Maass, Modelling Simul. Mater. Sci. 
Eng. 21, 035007 (2013). [2] P. M. Derlet and R. Maass, J. Appl. Phys. 
120, 225101 (2016). [3] P. M. Derlet and R. Maass, Phys. Rev. E 94, 
033001 (2016). Minden érdeklődőt szívesen várunk. A szemeszter 
szemináriumainak programja megtalálható a http://metal.elte.hu honlapon 
a Szemináriumok címszó alatt Kovács Zsolt