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DTSTART:20141212T110000
DTEND:20141212T120000
SUMMARY:Dynamic Discrete Dislocation Plasticity for Extremely High Strain Rates
DESCRIPTION:<p style="text-align: left;">A DCAMM seminar&nbsp;will be presented by </p>
\n<p style="text-align: center;"><b>Dr., PhD Daniel S. Balint<br />
\nDept. of Mechanical Engineering<br />
\nImperial College London</b><b>&nbsp;<br />
\nUnited Kingdom</b></p>
\n<p style="text-align: left;"><strong>Abstract</strong>: <br />
\n<br />
\nTraditionally, the study of plastic relaxation processes under weak shock loading and high strain rates in crystalline materials has been <br />
\nbased on direct experimental measurement of the macroscopic response of the material. Using this data, well-known macroscopic constitutive laws and equations of state have been formulated. However, direct simulation of dislocations as the dynamic agents of plastic relaxation in those circumstances remains a challenge. <br />
\n<br />
\nCurrent Discrete Dislocation Plasticity (DDP) methods, where dislocations are modeled as discrete line singularities in an elastic <br />
\ncontinuum, are unable to adequately simulate plastic relaxation because they treat dislocation motion quasi-statically, thus neglecting the time-dependent nature of the elastic fields and assuming that they instantaneously acquire the shape and magnitude predicted by <br />
\nelastostatics. Under shock loading, this assumption leads to artifacts that can only be overcome with a fully time-dependent formulation <br />
\nof the elastic fields. The first part of this talk will be an overview of planar discrete dislocation plasticity, including a brief summary of <br />
\nquasi-static studies on size effects conducted over the last ten years.<br />
\n<br />
\nIt will then be shown that the quasi-static approximation is unsuitable for very high strain rates (~10^6 and higher). Finally, a truly <br />
\ndynamic formulation for the creation, annihilation and arbitrary motion of straight edge dislocations will be presented. The Dynamic <br />
\nDiscrete Dislocation Plasticity (D3P) method will be applied in a two-dimensional model of time-dependent plastic relaxation under shock loading, and some relevant results on the decay of the elastic precursor will be presented.<br />
\n<br />
\nDanish pastry, coffee and tea will be served 15 minutes before the seminar starts. </p>
\n<p style="text-align: left;">All interested persons are invited. </p>
X-ALT-DESC;FMTTYPE=text/html:<p style="text-align: left;">A DCAMM seminar&nbsp;will be presented by </p>
\n<p style="text-align: center;"><b>Dr., PhD Daniel S. Balint<br />
\nDept. of Mechanical Engineering<br />
\nImperial College London</b><b>&nbsp;<br />
\nUnited Kingdom</b></p>
\n<p style="text-align: left;"><strong>Abstract</strong>: <br />
\n<br />
\nTraditionally, the study of plastic relaxation processes under weak shock loading and high strain rates in crystalline materials has been <br />
\nbased on direct experimental measurement of the macroscopic response of the material. Using this data, well-known macroscopic constitutive laws and equations of state have been formulated. However, direct simulation of dislocations as the dynamic agents of plastic relaxation in those circumstances remains a challenge. <br />
\n<br />
\nCurrent Discrete Dislocation Plasticity (DDP) methods, where dislocations are modeled as discrete line singularities in an elastic <br />
\ncontinuum, are unable to adequately simulate plastic relaxation because they treat dislocation motion quasi-statically, thus neglecting the time-dependent nature of the elastic fields and assuming that they instantaneously acquire the shape and magnitude predicted by <br />
\nelastostatics. Under shock loading, this assumption leads to artifacts that can only be overcome with a fully time-dependent formulation <br />
\nof the elastic fields. The first part of this talk will be an overview of planar discrete dislocation plasticity, including a brief summary of <br />
\nquasi-static studies on size effects conducted over the last ten years.<br />
\n<br />
\nIt will then be shown that the quasi-static approximation is unsuitable for very high strain rates (~10^6 and higher). Finally, a truly <br />
\ndynamic formulation for the creation, annihilation and arbitrary motion of straight edge dislocations will be presented. The Dynamic <br />
\nDiscrete Dislocation Plasticity (D3P) method will be applied in a two-dimensional model of time-dependent plastic relaxation under shock loading, and some relevant results on the decay of the elastic precursor will be presented.<br />
\n<br />
\nDanish pastry, coffee and tea will be served 15 minutes before the seminar starts. </p>
\n<p style="text-align: left;">All interested persons are invited. </p>

URL:http://www.dcamm.dk/da/Kalender/2014/12/Seminar_No_679
DTSTAMP:20260916T074900Z
UID:{F63B152B-C8BD-4667-A78E-B3D3AF24BA12}-20141212T110000-20141212T110000
LOCATION: Room 025, Building 404
, DTU, Technical University of Denmark
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