The natural honeycomb made from beeswax is an engineering marvel. Modern-day engineering has taken several inspirations from it in the form of hexagonal panels and cells made of various materials such as polymers, ceramics, and metals for light-weighting. Previously, characterizing this structure has relied on two-dimensional (2D) surface observations on the macroscale which have an inherently limited scope in understanding complex three-dimensional (3D) structures. As a result, several seminal features of the honeycomb that would have shed light on how it is constructed and what makes it so mechanically robust are not well understood. X-ray microtomography (XRM) is a powerful tool to characterize these complex structures non-destructively, yielding insights that are not possible without three-dimensional (3D) datasets. Further, when a time-resolved approach is adopted, where an external stimulus is applied, one can obtain four-dimensional (4D), time-resolved datasets. This provides unrivaled information on how complex 3D structures evolve over time when a stimulus is applied.

 

In this talk, I will discuss our time-resolved approach towards understanding how bees build out their hexagonal cells, both under normal and abnormal conditions. Several previously unreported, but seminal features of the honeycomb such as the “coping” and porosity at well-defined locations yielded insights into how the comb is constructed. The corrugated spine is seen to be the foundation on which all hexagonal cells are built on. Additionally, this work also explores how bees accommodate distortions within the ordered lattice during the merger of two combs. Behaviorally they are seen to reduce the distortion within cells to minimize the wastage of wax and to keep the cells usable. A 3D parameter using automated image processing was developed to quantify how distortions are accommodated in an ordered lattice.

 

I will further shed light on the mechanical behavior of the natural honeycomb arising from the corrugated nature of the spine and the gradient in its wall thickness which plays a role in crack deflection when the honeycomb is loaded under tension. When loaded under compression, the honeycomb lattice crumples in a manner to limit the damage to very local regions thereby forming a damage-tolerant crumple zone.