Harnessing the domino effect for deployable structures

February 10, 2020

If you've ever opened an umbrella or set up a folding chair, you've used a deployable structure - an object that can transition from a compact state to an expanded one. You've probably noticed that such structures usually require rather complicated locking mechanisms to hold them in place. And, if you've ever tried to open an umbrella in the wind or fold a particularly persnickety folding chair, you know that today's deployable structures aren't always reliable or autonomous.

Now, a team of researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have harnessed the domino effect to design deployable systems that expand quickly with a small push and are stable and locked into place after deployment.

The research is published in the Proceedings of the National Academy of Sciences (PNAS).

"Today, multi-stable structures are being used in a range of applications including reconfigurable architectures, medical devices, soft robots, and deployable solar panels for aerospace," said Ahmad Zareei, a postdoctoral fellow in Applied Mathematics at SEAS and first author of the paper. "Usually, to deploy these structures, you need a complicated actuation process but here, we use this simple domino effect to create a reliable deployment process."

Mechanically speaking, a domino effect occurs when a multi-stable building block (the domino) switches from its high-energy state (standing) to its low-energy state (laying down), in response to an external stimulus like the push of a finger. When the first domino is toppled, it transfers its energy to its neighbor, initiating a wave that sequentially switches all building blocks from high to low energy states.

The researchers focused on a simple system of bistable joints linked by rigid bars. They first showed that by carefully designing the connections between the links, transition waves could propagate through the entire structure -- transforming the initial straight configuration to a curved one. Then, using these building blocks, the research team designed a deployable dome that could pop-up from flat with one small push.

"Being able to predict and program this kind of highly non-linear behavior opens up many opportunities and has the potential not only for morphing surfaces and reconfigurable devices but also for propulsion in soft robotics, mechanical logic, and controlled energy absorption," said Katia Bertoldi, the William and Ami Kuan Danoff Professor of Applied Mechanics at SEAS and senior author of the study.

Bertoldi's lab is also working on understanding and controlling transition waves in two-dimensional mechanical metamaterials. In a recent paper, also published in PNAS, the team demonstrated a 2D system in which they can control the direction, shape, and velocity of transition waves by changing the shape or stiffness of the building blocks and incorporating defects into the materials.

The researchers designed materials wherein the waves moved horizontally, vertically, diagonally, circularly, and even wiggled back and forth like a snake.

"Our work significantly increases the design space and functionality of metamaterials, and opens up a new pathway to control deformations within the material at desired locations and speed," said Ahmad Rafsanjani, a postdoctoral fellow at SEAS and co-first author of the paper.
-end-
"Harnessing transition waves to realize deployable structures" was co-authored by Bolei Deng and supported by the National Science Foundation under Grant No. DMR-1420570 and from the Army Research Office under Grant No. W911NF-17-1-0147.

"Guided transition waves in multistable mechanical metamaterials" was co-authored by Lishuai Jin, Romik Khajehtourian, Jochen Mueller, Vincent Tournat, and Dennis M. Kochmann. It was supported by the US Army Research Office through Award W911NF-17-1-0147.

Harvard John A. Paulson School of Engineering and Applied Sciences

Related Engineering Articles from Brightsurf:

Re-engineering antibodies for COVID-19
Catholic University of America researcher uses 'in silico' analysis to fast-track passive immunity

Next frontier in bacterial engineering
A new technique overcomes a serious hurdle in the field of bacterial design and engineering.

COVID-19 and the role of tissue engineering
Tissue engineering has a unique set of tools and technologies for developing preventive strategies, diagnostics, and treatments that can play an important role during the ongoing COVID-19 pandemic.

Engineering the meniscus
Damage to the meniscus is common, but there remains an unmet need for improved restorative therapies that can overcome poor healing in the avascular regions.

Artificially engineering the intestine
Short bowel syndrome is a debilitating condition with few treatment options, and these treatments have limited efficacy.

Reverse engineering the fireworks of life
An interdisciplinary team of Princeton researchers has successfully reverse engineered the components and sequence of events that lead to microtubule branching.

New method for engineering metabolic pathways
Two approaches provide a faster way to create enzymes and analyze their reactions, leading to the design of more complex molecules.

Engineering for high-speed devices
A research team from the University of Delaware has developed cutting-edge technology for photonics devices that could enable faster communications between phones and computers.

Breakthrough in blood vessel engineering
Growing functional blood vessel networks is no easy task. Previously, other groups have made networks that span millimeters in size.

Next-gen batteries possible with new engineering approach
Dramatically longer-lasting, faster-charging and safer lithium metal batteries may be possible, according to Penn State research, recently published in Nature Energy.

Read More: Engineering News and Engineering Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.