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Investigation of the Scope and Limitations of Gradient Enhanced Crystal Plasticity in Explaining Macroscopic phenomena

Nijhuis, B. (2018) Investigation of the Scope and Limitations of Gradient Enhanced Crystal Plasticity in Explaining Macroscopic phenomena.

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Abstract:In many applications, it is important to model the constitutive response of materials. Most models however fail to predict macroscopically observed phenomena in plastic deformation. A gradient enhanced crystal plasticity model, in which slip gradients are incorporated in the hardening model through geometrically necessary dislocations (GNDs), is believed to include the physical basis to overcome this shortcoming. A comprehensive review about its general applicability in this content is however not available. Its scope and limitations in predicting plasticity phenomena are therefore assessed. Simulations are performed on two-dimensional representative volume elements consisting out of hexagonally shaped grains. The Hall-Petch effect in work hardening was very well represented by the length scale introduced by the slip gradients. Including GNDs extends the width of the stress distribution within the material. The presence of such a stress distribution results in small scale plasticity effects when the material is unloaded after deformation, enhancing the Bauschinger effect. Small amounts of anelasticity are also observed as a result, but not as pronounced as experimentally observed. The model is validated by a quantitative comparison of the evolution of GND-densities with experimental results.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
Link to this item:http://purl.utwente.nl/essays/76558
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