The relationship between active areas and boundaries with energy input
in snapping shells

Date:
April 5, 2022
Source:
Springer
Summary:
New research looks at how the geometry of shells relates to the
energy input required to actuate snap-through instability.



FULL STORY ==========================================================================
New research looks at how the geometry of shells relates to the energy
input required to actuate snap-through instability.


==========================================================================
In nature, diverse organisms such as the hummingbird and Venus flytrap
use rapid snapping motions to capture prey, inspiring engineers to
create designs that function using snap-through instability of shell structures. Snapping rapidly releases stored elastic energy and does not require a continuously applied stimulus to maintain an inverted shape
in bistable structures.

A new paper published in EPJ Eauthored by Lucia Stein-Montalvo,
Department of Civil and Environmental Engineering, Princeton University,
and Douglas P.

Holmes, Department of Mechanical Engineering, Boston University, along
with co- authors Jeong-Ho Lee, Yi Yang, Melanie Landesberg, and Harold
S. Park, examines how restricting the active area of the shell boundary
allows for a large reduction in its size, and decreases the energy input required to actuate snap- through behaviour in the shell to guide the
design of efficient snapping structures.

In the paper, the authors point out snap-through instability is a
particularly attractive mechanism for devices like robotic actuators
or mechanical muscles, optical devices, and even dynamic building
fac,ades. All of these rely on a combination of geometric bi-stability and snap-inducing stimulus to function that ranges from the mechanical, like
the torque in a child's popping jumping cap toy, or non-mechanical like temperature, voltage, a magnetic field, differential growth or swelling.

The researchers conducted two sets of experiments, one using the
residual swelling of bilayer silicone elastomers -- a process that
mimics differential growth, the other using a magneto-elastomer to induce curvatures that cause snap-through.

This mechanics-informed approach uncovered an analogy to the
bending-dominated boundary layer in inverted spherical caps. They found
that just as with inverted, passive spherical caps, the size of the
boundary layer is closely tied to stability. Additionally, the team
discovered that the location and size of the imposed bending region
determine whether it competes against or cooperates with the geometric
boundary layer, where the shell "wants" to bend.

Thus, the team's results reveal the underlying mechanics of snap-through
in spherical shells, offering an intuitive route to optimal design for efficient snap-through.


========================================================================== Story Source: Materials provided by Springer. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Lucia Stein-Montalvo, Jeong-Ho Lee, Yi Yang, Melanie Landesberg,
Harold
S. Park, Douglas P. Holmes. Efficient snap-through of spherical caps
by applying a localized curvature stimulus. The European Physical
Journal E, 2022; 45 (1) DOI: 10.1140/epje/s10189-021-00156-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220405115239.htm

--- up 5 weeks, 1 day, 10 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)