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Modeling of high strain rate and str...

Shehadeh, Mu'tasem A.

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Modeling of high strain rate and strain localization in FCC single crystals: Multiscale dislocation dynamics analyses.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Modeling of high strain rate and strain localization in FCC single crystals: Multiscale dislocation dynamics analyses./
Author:	Shehadeh, Mu'tasem A.
Description:	175 p.
Notes:	Source: Dissertation Abstracts International, Volume: 66-05, Section: B, page: 2792.
Contained By:	Dissertation Abstracts International66-05B.
Subject:	Engineering, Mechanical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3176473
ISBN:	0542154528

Modeling of high strain rate and strain localization in FCC single crystals: Multiscale dislocation dynamics analyses.
Shehadeh, Mu'tasem A.

Modeling of high strain rate and strain localization in FCC single crystals: Multiscale dislocation dynamics analyses. - 175 p.

Source: Dissertation Abstracts International, Volume: 66-05, Section: B, page: 2792.

Thesis (Ph.D.)--Washington State University, 2005.

In this work, the deformation process in FCC single crystals under high strain rate ranging between 105 s-1 to 108 s-1 is investigated using a multiscale model of plasticity that couples discrete dislocation dynamics and finite element analyses. Computer simulations are carried out to mimic the shock loading condition involved in high intensity laser experiments. In the first part of this study, the effects of peak pressure, shock pulse duration, crystal anisotropy and the nonlinear elastic properties on the interaction between shock waves and preexisting dislocation sources are investigated. Our calculations show that the dislocation density is proportional to strain rate, pulse duration and crystal orientation, and that the dislocation density increases with pressure proportional to a power law of 1.70 for pressure greater than 30 GPa. The results suggest that while the inclusion of pressure-dependent elastic properties for isotropic media leads to faster wave propagation speed, incorporating the effect of crystal anisotropy in the elastic properties results in orientation dependent wave speed and peak pressure. The relaxed configurations of dislocation microstructures showed the formation of micro bands coincident with the {111} whose characteristics are strain rate and orientation dependent.

ISBN: 0542154528Subjects--Topical Terms:

783786
Engineering, Mechanical.

Modeling of high strain rate and strain localization in FCC single crystals: Multiscale dislocation dynamics analyses.
LDR:03655nmm 2200313 4500 001 1818363
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008 130610s2005 eng d
020 $a 0542154528
035 $a (UnM)AAI3176473
035 $a AAI3176473
040 $a UnM $c UnM
100 1 $a Shehadeh, Mu'tasem A. $3 1907697
245 1 0 $a Modeling of high strain rate and strain localization in FCC single crystals: Multiscale dislocation dynamics analyses.
300 $a 175 p.
500 $a Source: Dissertation Abstracts International, Volume: 66-05, Section: B, page: 2792.
500 $a Chair: Hussein M. Zbib.
502 $a Thesis (Ph.D.)--Washington State University, 2005.
520 $a In this work, the deformation process in FCC single crystals under high strain rate ranging between 105 s-1 to 108 s-1 is investigated using a multiscale model of plasticity that couples discrete dislocation dynamics and finite element analyses. Computer simulations are carried out to mimic the shock loading condition involved in high intensity laser experiments. In the first part of this study, the effects of peak pressure, shock pulse duration, crystal anisotropy and the nonlinear elastic properties on the interaction between shock waves and preexisting dislocation sources are investigated. Our calculations show that the dislocation density is proportional to strain rate, pulse duration and crystal orientation, and that the dislocation density increases with pressure proportional to a power law of 1.70 for pressure greater than 30 GPa. The results suggest that while the inclusion of pressure-dependent elastic properties for isotropic media leads to faster wave propagation speed, incorporating the effect of crystal anisotropy in the elastic properties results in orientation dependent wave speed and peak pressure. The relaxed configurations of dislocation microstructures showed the formation of micro bands coincident with the {111} whose characteristics are strain rate and orientation dependent.
520 $a In the second part of this study, shock-induced dislocation nucleation is investigated. Shock waves with strength ranging from 10 to 60 GPa are launched in copper perfect crystals resulting in the nucleation of large number of dislocation loops at the wave front. Once the dislocation loops are nucleated, they grow in all directions in their slip planes forming a three dimensional microstructures consisting of dislocation entanglements and weak cellular structure. By this plasticity mechanism, we found that uniaxially compressed material relaxes to a hydrostatically compressed state (1D → 3D) as observed in the experiment.
520 $a In the third part of this study, the effect of finite element boundary condition on wave propagation is investigated by implementing periodic boundary condition and comparing its results with free and confined boundary conditions. The results show that confined and periodic boundary conditions based on node-to-node matching are suitable to model shock wave propagation. Mesh sensitivity analyses for steep and ramp shock waves show that the convergence in the ramp wave occurs at relatively coarse mesh density when compared to the steep wave. The effect of lattice rotation on strain localization was also investigated. The results show that more strain localization occurs when slip rotation is taken into account.
590 $a School code: 0251.
650 4 $a Engineering, Mechanical. $3 783786
650 4 $a Applied Mechanics. $3 1018410
650 4 $a Engineering, Materials Science. $3 1017759
690 $a 0548
690 $a 0346
690 $a 0794
710 2 0 $a Washington State University. $3 678588
773 0 $t Dissertation Abstracts International $g 66-05B.
790 1 0 $a Zbib, Hussein M., $e advisor
790 $a 0251
791 $a Ph.D.
792 $a 2005
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3176473