Fracture and Fragmentation
Fragmentation phenomena are all around us, from the atomistic scale up to the universe. On the industrial scale, they are the underlying process of every comminution process, for rocks, railway ballast, clinker grinding to cement and many others. Fragmentation is closely linked to dynamic crack propagation. Discrete Element Methods are most suitable, and we developed several codes to study dynamic crack propagation, impact fragmentation of brittle, disordered materials, of multiphase materials like clinker, with impact fatigue or ultra-sound assistance, of solid and shell type bodies, inside granular packings and much more.
Simulation of dynamic crack propagation with crack branching at different fractions of the Rayleigh wave speed.
Outreach:
- P.S. Iliev, F.K. Wittel, H.J. Herrmann: Evolution of fragment size distributions from crushing of granular materials, Physical Review E 99 (2019), 012904.
- R.K. Mishra, D. Geissbühler, H. Carmona, F.K. Wittel, M.L. Sawley, M. Weibel, E. Gallucci, H. J. Herrmann, H. Heinz, R. J. Flatt: En route to a multi-model scheme for clinker comminution with chemical grinding aids, Advances in Applied Ceramics (AAC) 114 (2015), 393-401.
- H.A. Carmona, A.V. Guimaraes, J.S. Andrade Jr., I. Nikolakopoulos, F.K. Wittel, H.J. Herrmann: Fragmentation process in two-phase materials, Physical Review E 91 (2015), 012402.
- H.A. Carmona, F.K. Wittel, F. Kun: From fracture to fragmentation with discrete element modeling: Mesoscopic approach to the breaking of heterogeneous materials, Eur. Phys. J. Special Topics, 223 (11/2014), 2369-2382.
- F.K. Wittel: Fragmentation of Spheres in Ultrasound Assisted Impact Comminution, Granular Matter 12 (4/2010), 447-455.
- F.K. Wittel, H.A. Carmona, F. Kun, H.J. Herrmann: Mechanisms in Impact fragmentation, International Journal of Fracture 154 (1-2/2009), 105-117.
- H.A. Carmona, F.K. Wittel, F. Kun, H.J. Herrmann: Fragmentation processes in impact of spheres, Physical Review E 77 (2008), 051302.
- F.K. Wittel, F. Kun, H.J. Herrmann, B.H. Kröplin: Study on the fragmentation of shells, International Journal of Fracture 140 (2006), 243-254.
- F. Kun, F.K. Wittel, H.J. Herrmann, B.H. Kröplin, K.M. Malöy: Scaling behaviour of fragment shapes, Physical Review Letters 96 (2006), 025504.
- F.K. Wittel, F. Kun, H.J. Herrmann, B.H. Kröplin: Breakup of shells under explosion and impact, in Physical Review E 71 (2005), 016108.
- F.K. Wittel, F. Kun, H.J. Herrmann, B.H. Kröplin: Fragmentation of shells, Physical Review Letters 93 (3/2004), 035504.
Funding by ETH research Grant, KTI project and DFG.