Hard Spheres, Soap Bubbles, and Hydrogels in Research and Education
Citation:
Irannezhad, Ali, Hard Spheres, Soap Bubbles, and Hydrogels in Research and Education, Trinity College Dublin.School of Physics, 2023Download Item:
Abstract:
This thesis concerns various experiments using hard spheres, soap bubbles,
hydrogel spheres, and soap films in which we will show these are suitable
candidates for research and can be easily performed in universities, classrooms,
or even at home to express physical concepts such as instability, symmetry
breaking, buckling, dense packing, and failure.
Initially, we briefly present examples of using hard spheres and soap film
that are used to demonstrate science. For example, we describe how soap
films can be used to help with minimization problems such as the Motorway
Problem.
We then discuss the buckling behavior of a linear chain of hard spheres
confined in a transverse harmonic potential that displays instability and buckling under compression and tilt. We will discuss different arrangements of such
chains under low and high compressions and under tilt. At low compression,
a modulated zig-zag arrangement is observed which is followed by a localized
buckling at higher compression and will end with a doublet structure at higher
compressions. In addition, we will demonstrate there is a critical tilt for the
buckling of the system.
Friction plays a critical role in our buckling experiments using hard spheres.
To eliminate friction, we will discuss an alternative for buckling experiments
using soap bubbles. So, a linear chain of soap bubbles is investigated under
compression. Due to the deformability of soap bubbles, we show the onset
of buckling occurs at a critical value of compression. Also, our findings are in good agreement with the simulation. In addition, we present how the
transverse bubble width changes as a function of compression.
Packing experiments using hydrogel spheres will be introduced. First, we
will demonstrate how a line of hydrogel spheres lying at the bottom of a
cylindrical tube can show a zigzag pattern as observed using a chain of hard
spheres and soap bubbles. Then I will show various types of packing problems
using hydrogel spheres. The experiments are easy to set up and thus suitable
for use in the classroom or in the undergraduate teaching laboratory.
As bubbles are a relatively easy system to experiment with, we will introduce another field of research where soap films/bubbles can be used to obtain experimental data related to studies of failure/mortality. We introduce controlled experiments using individual soap films confined in the middle of Perspex tubes as a simple physical system to model the failure and mortality.
Our examination of soap film lifetime statistics has yielded valuable insights
and showed that individual soap films displayed a common pattern of mortality/failure called the bath-tub curve. Our findings show a linear relationship
between film lifetime and tube length and introduce a relationship between
defects in the system and soap film lifetime.
Finally, we conclude our results and introduce suggestions for further research. First, we suggest another buckling experiment using slanted stoppers
instead of flat stoppers to investigate the effect of changing the boundary
conditions in buckled structures. We show that instead of using flat stoppers
if one uses slanted stoppers that leads to a double-peak structure, and rather
than a localized buckling at high compression, a modulated zigzag can be
observed.
In addition, we suggest further exploration of soap film lifetime to investigate the effect of external factors on the ageing and failure of soap films that
can be used as a simple system to see how mortality curves look like for people
that always lived under poor conditions.
Sponsor
Grant Number
Trinity College Dublin Provost?s Ph.D. Project Awards
Author's Homepage:
https://tcdlocalportal.tcd.ie/pls/EnterApex/f?p=800:71:0::::P71_USERNAME:IRANNEZADescription:
APPROVED
Author: Irannezhad, Ali
Sponsor:
Trinity College Dublin Provost?s Ph.D. Project AwardsAdvisor:
Hutzler, StefanPublisher:
Trinity College Dublin. School of Physics. Discipline of PhysicsType of material:
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