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Grain Refinement

Predictive Modeling of Nanocrystalline Structures via SPD

posted Nov 21, 2011, 8:35 AM by Hongtao Ding   [ updated Nov 21, 2011, 8:43 AM ]

Microstructural evolution of workpiece materials during cutting is quantitatively modeled using a dislocation density-based model.  This work is the first of its kind in this field.  The material strengthening mechanism and dislocation density change were successfully modeled for cutting and other SPD processes such as laser shock peening and multiple-pass cold rolling.

For the excellence of this work, I received the ASME Best Paper Award at the 6th ASME 2011 International Manufacturing Science and Engineering Conference (MSEC2011) in Corvallis, Oregon, in June 2011 for the paper entitled "Dislocation density-based grain refinement modeling of orthogonal cutting of commercially pure titanium".  It was selected out of more than 180 papers in the manufacturing area.  

Fig. 1 TEM images of grain refinement of CP Ti produced various SPD processes

Fig. 2 CEL model

Fig. 3 Dislocation field simulation

Fig. 4 Strain rate simulation

Fig. 5 Dislocation density-based plasticity model predictions for Al 6061 T6

Fig. 6 Grain size prediction of Al 60o61 T6

Fig. 7 Dislocation field simulation of copper

Coupled Eulerian-Lagrangian (CEL) FE model

posted Nov 20, 2011, 3:23 PM by Hongtao Ding

A coupled Eulerian-Lagrangian (CEL) model was developed to simulate steady-state chip formation and grain refinement in two-dimensional (2D) orthogonal cutting by using the commercial software Abaqus.

One of the main drawbacks of simulation of machining is the extremely high computational cost of simulations, while using the CEL model developed in this study, the computational time was reduced to about 4 hours from several days for simulation of steady-state chip formation at the low cutting speeds.

CEL Model Simulation

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