A Multiple Slip Plane Model for Crack-Tip Plasticity

1999 ◽  
Vol 578 ◽  
Author(s):  
S. J. Noronha ◽  
S. G. Roberts ◽  
A. J. Wilkinson
Keyword(s):  
Slip Plane ◽  
Crack Tip ◽  
Dislocation Dynamics ◽  
Plane Model ◽  
Dislocation Source ◽  
Single Slip ◽  
Multiple Slip ◽  
Brittle To Ductile Transition ◽  
Slip Planes ◽  
Crack Tip Plasticity

AbstractA single slip plane dislocation dynamics based model for the brittle to ductile transition has been extended to have multiple slip planes around the crack-tip. The crack-tip plastic behaviour is studied for a variety of dislocation source configurations. The results are presented for the case of iron. The effect of modelling the plastic-zone as a single slip plane and as an array of parallel slip planes are compared.

Dislocation Dynamics Simulations of Dislocation-Particle Bypass Mechanisms

2020 ◽  
Vol 985 ◽  
pp. 35-41
Author(s):  
Jianbin Liu ◽  
Shinji Muraishi
Keyword(s):  
Slip Plane ◽  
Dislocation Line ◽  
Simulation Method ◽  
Dislocation Motion ◽  
Dislocation Dynamics ◽  
Dislocation Slip ◽  
Relative Height ◽  
Dislocation Interaction ◽  
Slip Planes ◽  
Line Elements

Effect of precipitation strengthening on metal is generally attributed to the dislocation interaction with the precipitate which acts as the barrier to the dislocation motion on the slip plane. In order to achieve better understanding of critical events of dislocation motion and evolution of dislocation microstructure, we have developed numerical simulation method of dislocation-dislocation and dislocation-particle interactions by means of discrete dislocation dynamics at mesoscopic scale. In this work, Green’s function method is utilized for the computation of the stress fields of dislocation and misfitting particle, and the interaction forces acting on the dislocation. We also proposed the efficient algorithm of the connectivity vector for the dislocation line elements, linked-list data structure, to deal with the flexible interaction of dislocation line elements. The geometrical effect of dislocation slip planes on the dislocation bypassing behaviors is tested by changing the relative height of dislocation slip plane against the center plane of spherical particle, where cross slip event is also taken into account for the dislocation motion. Simulation results show a wide variety of topological changes of dislocation during motion on the slip planes around the particle, which results from the stress field of the particle varied with the relative height between the dislocation slip plane and center plane of particle. The full analysis of the mechanisms of dislocation line bypassing misfitting particle has been explained in this study.

Crack Tip Plasticity By Classic Dislocation Dynamics

2008 ◽  
Vol 33-37 ◽  
pp. 97-102
Author(s):  
Hiroomi Homma ◽  
Huu Nhan Tran
Keyword(s):  
Short Pulse ◽  
Crack Tip ◽  
Plastic Zone Size ◽  
Dislocation Dynamics ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Crack Tip Plasticity ◽  
Crack Tip Opening

Under very short pulse loads in range from 25 to 100 μs, crack tip plasticity a head of the crack tip in the mode I condition was investigated by discrete dislocation dynamics. The obtained dislocation array parameters such as the number of dislocations, dislocation distribution density, crack tip opening displacement and plastic zone size increase with the magnitude of stress intensity factor, KI and pulse durations. The numerical results were well compared with the experimental ones.

Cooperative Dislocation Generation And The Brittle-To-Ductile Transition

1995 ◽  
Vol 409 ◽  
Author(s):  
M. Khantha ◽  
D. P. Pope ◽  
V. Vitek
Keyword(s):  
Critical Temperature ◽  
Crack Tip ◽  
Two Dimensions ◽  
Dislocation Dynamics ◽  
Dislocation Generation ◽  
Thermally Induced ◽  
Brittle To Ductile Transition ◽  
Thermally Driven ◽  
Characteristic Features ◽  
Ductile Behavior

AbstractThe characteristic features of the brittle-to-ductile transition are explained using a model of cooperative dislocation generation. In two dimensions, the onset of the ductile behavior corresponds to a thermally-driven, stress-assisted dissociation of many atomic-size dislocation dipoles in the vicinity of the crack tip above a critical temperature Tc. The instability is caused by thermally induced screening of dislocation interactions as in the Kosterlitz-Thouless phase transition. However, the critical temperature is well below the melting temperature in the presence of a stress. The nature of dislocation dynamics in the vicinity of the crack tip is also described and its role in the onset of the cooperative instability is examined. The origin of the correlation between the strain-rate dependence of the transition temperature and the temperature dependence of dislocation mobility is explained.

Fracture Toughness Enhanced by Severe Plastic Deformation in Low Carbon Steel

2008 ◽  
Vol 584-586 ◽  
pp. 637-642 ◽  
Author(s):  
Masaki Tanaka ◽  
Naoki Fujimoto ◽  
Tatsuo Yokote ◽  
Kenji Higashida
Keyword(s):  
Fracture Toughness ◽  
Carbon Steel ◽  
Low Temperatures ◽  
Low Carbon Steel ◽  
Crack Tip ◽  
Dislocation Dynamics ◽  
Grain Refining ◽  
Low Carbon ◽  
Dislocation Source ◽  
Crack Tip Shielding

The enhancement of toughness at low temperatures in fine-grained low carbon steel was studied, basing on the theory of crack-tip shielding due to dislocations. Low carbon steel was subjected to an accumulative roll bonding (ARB) process for grain refining. The grain size perpendicular to the normal direction was decreased to approximately 200nm after the ARB process. The fracture toughness of low carbon steel with the ARB process was measured at 77K by four-point bending, comparing with the fracture toughness of those without the ARB. It was found that the value of fracture toughness at 77K was increased by grain refining due to the ARB process, indicating that the ARB process enhances toughness at low temperatures and that the brittle-to-ductile transition (BDT) temperature shifted to a lower temperature. Quasi-two-dimensional simulations of dislocation dynamics, taking into account crack tip shielding due to dislocations, were performed to investigate the effect of a dislocation source spacing along a crack front on the BDT. The simulation indicates that the BDT temperature is decreased by decreasing the dislocation source spacing.

Monotonic and cyclic crack tip plasticity

1984 ◽  
Vol 6 (1) ◽  
pp. 17-24 ◽  
Author(s):  
L GUERRAROSA ◽  
C MOURABRANCO ◽  
J RADON
Keyword(s):  
Crack Tip ◽  
Crack Tip Plasticity
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