QUT designs a 3D printed product to protect buildings from impact damage

Image credit: QUT.

A material used in running shoes and memory foam pillows inspired the design of a 3D printed product that could help protect buildings from collision damage and other high impact forces the equivalent of a car traveling at 60 km / h.

Dr. Tatheer Zahra of QUT at the Center for Materials Science and School of Civil and Environmental Engineering used commercial bioplastics to 3D print geometric shapes that mimick the behavior of auxetic materials.

“Instead of flattening out when stretching or bulging when squeezing, auxetic materials expand or contract in all directions at the same time, making them very energy-absorbing and resilient,” said Zahra.

“But the existing commercial auxetic material is expensive and not available locally, so I designed geometrical shapes that achieved the same behavior.”

3D printing auxetic geometries could potentially replace steel and fiber reinforced polymer fabric reinforcements in composites and could also be used as flexible and versatile bulkhead plaster.

The energy absorption would correspond to a 20 mm thick reinforced composite protective plaster over a full-surface building wall, which could potentially withstand the impact force of a car at 60 km / h.

“On a scale, composites embedded with these geometries could theoretically withstand high shock or impact energy caused by gas explosions, earthquakes and wind forces, and car collisions,” said Zahra.

“There are an estimated 2,000 car accidents in Australia each year. Direct building damage costs of 2.5 percent would add up to the damage calculation at approximately $ 38.65 million a year for residential construction. Since vehicles crash into homes, office buildings, restaurants and grocery stores, the cost of structural damage is likely to be higher. The loss of human life would be the highest cost factor. “

Zahra said protecting masonry walls is especially important as it is an essential part of most commercial and residential buildings.

“Masonry is a very cheap material that is resistant to noise and heat and has better fire protection properties compared to wood or steel, but its mortar joints weaken the overall strength of the structure,” she said.

“If auxetic geometries were embedded in the mortar to create protective compounds, they would also be protected from microorganisms and temperatures above 60 ° C and should outlast the construction life of the structure.”

Tried and tested on a laboratory scale, the goal is now to test the designs on masonry and concrete structures at their original scale in the QUT Banyo Pilot Plant.

“The designs would have good prospects for commercialization through additive manufacturing as the production process is flexible and materials are readily available,” said Zahra.

“3D printing would also enable us to adapt the material, the size or the design of geometric shapes to different structures and load requirements.”

Bioplastics offered a more sustainable alternative with low CO2 emissions to fiber-reinforced plastic or other non-biodegradable polymers. It was also less expensive than using available auxetics, which could cost up to $ 400 per square meter and were not biodegradable.

Zahra’s research was published in Intelligent materials and structures.

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