Fracture and fragmentation of solids  Page description

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Details of project

  
Identifier
49209
Type K
Principal investigator Kun, Ferenc
Title in Hungarian Szilárdtestek törése és fragmentációja
Title in English Fracture and fragmentation of solids
Panel Physics 1
Department or equivalent Department of Theoretical Physics (University of Debrecen)
Participants Nagy, Sándor
Varga, Imre
Starting date 2005-01-01
Closing date 2009-12-31
Funding (in million HUF) 6.800
FTE (full time equivalent) 8.00
state closed project





 

Final report

  
Results in Hungarian
Rendezetlen mikroszkópikus tulajdonságokkal rendelkező anyagok törési folyamatát vizsgáltuk konstans és periódikusan változó külső terhelés alatt. Megmutattuk, hogy a makroszkópikus törés kritikus időpontjához közeledve a rendszert univerzális skálatörvények jellemzik, amelyek felhasználhatóak a makroszkópikus törés előrejelzésére is. A creep és fatigue törés lehetséges mikroszkópikus mechanizmusaként részletesen elemeztük a nemlineáris repedéshalmozódás és a termikus fluktuációk szerepét. Kísérleteket végeztünk zárt, héjszerű struktúrák robbanás okozta fragmentációjának megértésére. Megmutattuk, hogy a héjak feltörése egy kétlépéses folyamat, amelynek első szakaszát a húzó, a másodikat pedig a hajlító feszültség dominálja. Kimutattuk, hogy a fragmensek alakját is skálatörvények jellemzik. Nagytömegű fragmensekre erős tömeg-sebesség korrelációt találtunk. Elemeztük a ferromágneses anyagok dinamikus törését kísérő mágneses és elektromos zajspektrum belső struktúráját. A mérési eredmények értelmezésére kidolgoztunk egy szálköteg modellt, amellyel pontos leírását tudtuk adni a zajra kapott mérési eredményeknek.
Results in English
We investigated the damage and fracture of disordered materials under constant and periodically varying external loads. We showed that the system is characterized by universal scaling laws when approaching the critical time of macroscopic fracture, which can be used to design forecasting techniques of the imminent failure event. As two possible microscopic mechanisms of creep rupture and fatigue fracture, we studied in details the effect of non-linear damage accumulation and of the thermal fluctuations. We performed experiments to obtain a deeper understanding of the fragmentation of closed shell structures due to energetic explosions. We pointed out that the breakup of shells is a two-step process, where the first phase of the process is determined by tensile stresses, while the second one is dominated by bending forces. We found that the shape of fragments obeys also universal scaling laws, furthermore, the fragments of large mass exhibit a strong mass-velocity correlation. We analyzed the structure of electric and magnetic noise spectra recorded during dynamic fracture of ferromagnetic materials. We worked out a fiber bundle model which provides a comprehensive description of the crack propagation and the emergence of crackling noise.
Full text http://real.mtak.hu/1939/
Decision
Yes





 

List of publications

  
F. K. Wittel, F. Kun, H. J. Herrmann, and B.-H. Kröplin: Study on the fragmentation of shells, International Journal of Fracture 140, 255, 2006
R. C. Hidalgo, F. Kun, and H. J. Herrmann: Slow relaxation of fiber composites, variable range of interaction approach, Physica A 347, 402, 2005
B. Behera, F. Kun, S. McNamara, and H. J. Herrmann: Fragmentation of a circular disc by impact on a frictionless plate, Journal of Physics-Condensed Matter 17, 2439, 2005
S. Nagy, I. Varga and F. Kun: A stochastic interface model for the fracture of bars, in Proceedings of 16th European Conference on Fracture, July 3-7, 2006, Greece, konferencia proceedings, 2006
H. J. Herrmann, F. K. Wittel, and F. Kun: Fragmentation, Physica A 371, 59, 2006
K. Kovács and F. Kun: Mass-velocity correlation in impact fragmentation, Proceedings of Multiscale Materials Modelling (MMM2006), International Conference, September 18-22, Freiburg, Germany, pp. 324-327, 2006
F. Kun, F. Raischel, R. C. Hidalgo, and H. J. Herrmann: Extensions of fiber bundle models, Modelling Critical and Catastrophic Phenomena in Geoscience: A Statistical Physics Approach, Lecture Notes in Physics (LNP) 705, Springer Verlag, Berlin (2006), pp. 57-92, 2006
F. Kun, F. Raischel, R. C. Hidalgo, and H. J. Herrmann: Extension of Fiber Bundle Models for Creep Rupture and Interface Failure, International Journal of Fracture 140, 243, 2006
Z. Halász and F. Kun: Fiber bundle model with stick-slip dynamics, in Proceedings of Multiscale Materials Modelling (MMM2006), International Conference, September 18-22, Freiburg, Germany, pp. 321-323., 2006
F. Raischel, F. Kun, and H. J. Herrmann: Fiber Bundle Models for Composite Materials, in Proceedings of Conference on Damage in Composite Materials: Simulation and Non-Destructive Testing, 18-20 September 2006, Stuttgart, Germany., 2006
H. A. Carmona, F. Kun, J. S. Andrade Jr., and H. J. Herrmann: Computer simulation of fatigue under diametrical compression, Physical Review E 75, 046115, 2007
F. Raischel, F. Kun, and H. J. Herrmann: Continuous damage fiber bundle model for strongly disordered materials, Physical Review E77, 046102, 2008
H. A. Carmona, F. Wittel, F. Kun, and H. J. Herrmann: Fragmentation processes in impact of spheres, Physical Review E77, 051302, 2008
F. Kun, Z. Halász, J. S. Andrade Jr., and H. J. Herrmann: Crackling noise in sub-critical fracture of heterogeneous materials, Journal of Statistical Mechanics: Theory and Experiment P01021, 2009
F. Kun, F. K. Wittel, H. J. Herrmann, B.-H. Kröplin, and K.-J. Maloy: Scaling behaviour of fragment shapes, Physical Review Letters 96, 025504, 2006
F. Kun, H. A. Carmona, J. S. Andrade Jr., and H. J. Herrmann: Universality behind Basquin's law of fatigue, Physical Review Letters 100, 094301, 2008
N. Yoshioka, F. Kun, and N. Ito: Size scaling and bursting activity in thermally activated breakdown of fiber bundles, Physical Review Letters 101, 145502, 2008
R. C. Hidalgo, K. Kovacs, I. Pagonabarraga, and F. Kun: Universality class of fiber bundles with strong heterogeneities, Europhysics Letter 81, 54005, 2008
F. Raischel, F. Kun, and H. J. Herrmann: Simple beam model for the shear failure of interfaces, Physical Review E 72, 046126, 2005
F. Raischel, F. Kun, and H. J. Herrmann: Local load sharing fiber bundles with a lower cutoff of strength disorder, Physical Review E 74, 035104(R), 2006
F. Raischel, F. Kun, and H. J. Herrmann: Failure process of a bundle of plastic fibers, Physical Review E 73, 066101, 2006
F. Kun, M.H.A.S. Costa, R.N. Costa Filho, J. S. Andrade Jr., S. Zapperi, and H. J. Herrmann: Fatigue fracture of disordered materials, Journal of Statistical Mechanics: Theory and Experiment, P02003, 2007
F. Kun and S. Nagy: Damage process of a fiber bundle with a strain gradient, Physical Review E77, 016608, 2008
K. Kovacs, S. Nagy, R. C. Hidalgo, F. Kun, H. J. Herrmann, and I. Pagonabarraga: Critical ruptures in a bundle of slowly relaxing fibers, Physical Review E77, 036102, 2008



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