Discrete dislocation simulations of taper effects in micropillar compression

2D discrete dislocation simulations, enhanced by a set of physically based rules to mimic 3D processes of dislocation activity, are used to investigate the effects of taper on micropillar plasticity. Pillars with material properties of Al and a height to diameter aspect ratio of 3 are loaded in compression. The mechanical response of the compressed pillars with mid-height diameter of D = 0.4, 0.8. 1.6, 3.2, and 9.6 m and taper angle of 0 and 10 are studied. Untapered pillars show a strong size effect as the diameter is reduced from 9.6 to 0.4 m, in keeping with previous findings. The analyses show that tapered pillars exhibit a less pronounced size effect in an average sense. The build-up of effective GND density, which was previously identified as one of the origins of the size effect in untapered pillars, diminishes in tapered pillars. The analyses show that the size effect cannot be caused by the tapering since the latter does not enhance the size effect but rather decreases it.

Discrete dislocation simulations of taper effects in micropillar compression Conference Paper