Australian honeycombs abuzz with possibilities for sustainable additive manufacturing

WEST LAFAYETTE, Ind. — Australian stingless bees have turned the traditional vertical honeycomb on its side, resulting in natural building concepts and efficiency that may provide new ideas for sustainable manufacturing.

A cross section of the bees’ home reveals a detailed architectural structure using discs for the honeycomb’s foundation that spiral upward like a ramp, with design intricacies that solidify the structure, which is made mostly of wax. These honeycombs are most often found in trees.

Nikhilesh Chawla, Purdue’s Ransburg Professor in Materials Engineering and an expert in four-dimensional materials science, said closer inspection shows specifically located supports between the discs. The specialized design aspects and material uses could translate into new concepts for structural materials and additive manufacturing.

“What is amazing about this is they actually make vertical pillars creating structural support between the discs, believe it or not,” Chawla said. “The bees recycle the comb materials and use a spiral construction to efficiently build and maintain temperature stability in the comb. We can learn so much from their intelligent and multifunctional approaches to manufacturing.”

Despite their important role in supporting the hive layers, Chawla said, the supports are not completely solid. But their size and placement are precise enough to allow bees room to go in and repair any damage that occurs.

Chawla’s work shows how humans can draw important lessons from the plant and animal worlds in a discipline called biomimicry, which investigates naturally occurring materials and behaviors and finds inspiration for the design of new products, systems and buildings.

The stingless bees are in a constant mode of building and tearing. Once an egg hatches, the cell it was in at the bottom of the hive is torn down, creating room there. New construction then begins moving upward in the hive’s continuous spiral.

“There is potential to learn from these reconfigurable structures they build and even the spiral, ramplike structures,” Chawla said.

Hives brought to Purdue from Australia over the summer are examined using 4D imaging, a sophisticated three-dimensional X-ray microscopy technique combined with a time lapse that provides an unprecedented means of studying and quantifying the honeycomb’s microstructure. The imaging offers a unique view into the hive without damaging it.

Aspects of honeycombs are already used in several applications, from construction and structural materials to shoes. But for the Australian stingless bee, materials usage is just as important as construction.

Nicole Balog is a graduate student in materials engineering working with Chawla on the research. She said the pillars and the honeycomb itself, unlike the honeycombs found in the U.S., aren’t made just of wax. Instead, the bees will collect tree resin in addition to pollen and bring those substances back to the hive. The resin is stored and mixed with wax for building later.

“So there’s a lot of questions that we have with the resin, like how much are they adding to the wax, and do they change the amount that they’re adding based on the location of the hive, the time of year and other factors?” she said. “Once we know how much they’re adding to it, how does that affect the mechanical properties of the hive?”

Chawla’s research into the stingless bees’ honeycomb is an extension of his initial work looking at the construction and makeup of honeycombs found in the U.S. His 2022 research revealed some of the junctions between the honeycomb cells found locally were created using less material, with the resulting porous connections resembling Swiss cheese.

Chawla is collaborating with Brock Harpur, an associate professor of entomology at the Purdue Bee Lab, and Ros Gloag, a senior lecturer at the University of Sydney in Australia.

In addition to his research, Chawla is the Purdue associate dean for engineering in Indianapolis.

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