ab500120f_si_001.pdf (1.39 MB)
Defect-Tolerant Bioinspired Hierarchical Composites: Simulation and Experiment
journal contribution
posted on 2015-05-11, 00:00 authored by Reza Mirzaeifar, Leon S. Dimas, Zhao Qin, Markus J. BuehlerDefect tolerance, the capacity of
a material to maintain strength
even under the presence of cracks or flaws, is one of the essential
demands in the design of composite materials, as manufacturing induced
defects, or those generated during operation, can lead to catastrophic
failure and dramatically reduce the mechanical performance. In this
paper, we combine computational modeling and advanced multimaterial
3D printing to examine the mechanics of several different classes
of defect-tolerant bioinspired hierarchical composites, built from
two base materials with contrasting mechanical properties (stiff and
soft). We find that in contrast to the brittle base constituents of
the composites, the existence of a hierarchical architecture leads
to superior defect-tolerant properties. We show that composites with
more hierarchical levels dramatically improve the defect tolerance
of the material. We also examine the effect of adding both self-similar
and dissimilar hierarchical levels to the materials architecture,
and show that the geometries with multiple hierarchical levels can
retain a significant portion of their fracture strength in the presence
of either large edge cracklike flaws or multiple small distributed
defects in the material. We compare the stress distributions in materials
with different numbers of hierarchies in both simulation and experiment
and find a more uniform stress distribution in the uncracked region
of materials with higher hierarchy levels. These results provide micromechanical
insights into the origin of the higher defect tolerance observed in
simulation and experiment.