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A new method to design artificial honeycombs

We have all seen what honeycombs look like, and the more fortunate among us have slurped honey off them too. What we don’t know is, honeybees have somehow hit upon the most efficient structure possible. Artificial structures that are built like a honeycomb allow us to achieve maximum stability at minimal cost, using minimal material.

Honeycomb structures are commonly used in aerospace and other fields of engineering due to their property of being lightweight, yet sufficiently strong. They have a tremendous ability to absorb energies arising out of high velocity impacts. Honeycomb materials in aluminum, fibreglass and composite materials have been featured in aircraft and rockets since the 1950s. To strike closer home, honeycomb shaped packaging material is common – in cardboard packaging, for instance.

Researchers at the Aerospace Engineering Department, IISc, have come up with a novel method of designing the peculiar geometric configuration of honeycombs. Various types of structures have been explored for designing honeycombs. One is, using a structure called “auxetic” lattice: when they are stretched in one dimension, unlike conventional structures, they show an increase in length in the other dimension(s). These kind of materials have potential application in the field of artificial medical prosthetics and aerospace.

While research has grown in fabricating structures with complicated auxetic geometries, attention has scarcely been given to structures with combined conventional and auxetic cores. The beauty of the combined design is that it has a superior “band gap property” in addition to having the advantages of the honeycomb structure. The periodic arrangement of lattices in a honeycomb core implies the structure will not feel the effect of loads.

“This design garnered wide praise when it was presented at the recent SPIE [international society for photonics and optics] conference in USA”, said Professor S Gopalakrishnan. “We want to build a sandwich structure with this design for the core.” A sandwich structure has a lightweight, deformable core sandwiched between two high strength layers. Such a structure being lightweight yet stiff is in high demand in aerospace applications.

Researcher Sushovan Mukherjee will be collaborating with a lab in University of Bristol, UK, where the fabrication of this structure will be carried out.

About the authors

Sushovan Mukherjee and Prof S Gopalakrishnan are at the Department of Aerospace Engineering, Indian Institute of Science, Bangalore.

Collaborator Fabrizio Scarpa is at the University of Bristol, UK.

About the paper

The paper appeared in the journal Proc. SPIE 9434, Nanosensors, Biosensors, and Info-Tech Sensors and Systems 2015. http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2241699