Faculty Profile: Matt
Allen
att
Allen always has enjoyed taking things apart to study how they work.
So when he entered Brigham Young University as an undergraduate, he
had no trouble selecting mechanical engineering to study. “Of
all the disciplines in science and engineering, I chose mechanical engineering
because I liked working on things that I could see,” he says.
“But ironically, over the past few years I’ve found myself
working more and more on things that are either too small to be seen,
or that you physically can’t touch.”
Allen is the department’s
newest assistant professor. His research falls into both experimental
and modeling realms. He studies dynamics and vibrations, system identification,
experimental modal analysis, the dynamics of micro and nano systems,
uncertainty in dynamic systems, and stochastic dynamic systems. He helps
maintain the department’s atomic force microscope laboratory and,
beginning in fall, will teach in such areas as dynamics, vibrations,
nanomechanics and experimental methods for dynamic systems.
Allen took a two-year break
from his under-grad studies at Brigham Young University to work as a
missionary in Guatemala. “Just long enough,” he says, “to
develop a serious addic-tion to black beans and to forget every scrap
of calculus that I had learned as a freshman.”
After completing his bachelor’s
degree, he completed MS and PhD degrees at Georgia Institute of Technology.
There, he developed an algorithm for detecting damage in structures.
“The idea is to take vibration measurements from a structure,
such as a bridge or the wing of an aircraft, and use the measurements
to determine if the structure is damaged,” he says.
The algorithm can process
data from many sensors, even in the presence of considerable noise,
and then deliver an accurate estimation of vibration properties such
as modal parameters and natural frequencies. Allen also applied it in
studies of failure in the tiny solder bumps that fasten centimeter-square
computer chips to a circuit board.
After he earned his PhD in
2005, he took a postdoctoral position in structural dynamics research
at Sandia National Laboratories. His group devised methods to increase
the life of high-speed micro-switches. Basically, his group tailored
the electrical signal that closes the switches to reduce dynamic forces
the switch experiences. “This would’ve been an easy task
for a single switch, but the project required a solution that would
work for an array of switches that were quite different from one another
due to manufacturing variability,” he says.
By modeling uncertainty
in the switch dimensions and material properties, he reduced switch-closing
velocity by a factor of four.
Much of his research has
been on inverse problems—in other words, measuring vibrations
from a structure and then using them to determine a desired property.
He began a piece of this work as an undergraduate during studies of
carbon-fiber materials that include a special layer of viscoelastic
material to improve their damping. “I developed a test system
that could estimate the stiffness and damping of the material from the
vibration measurements,” he says.
Allen has become interested
in applying some of his inverse techniques to improving the dynamic
or vibration performance of micro and nano devices. In atomic-force
microscopy, for example, he might improve image resolution or sample
scan-speed. “There might also be applications to biological systems,”
he says. “Dynamic material characterization methods are sometimes
more sensitive and easier to use than static methods.”
He also is studying ways
to model systems of interconnected components when it is impractical
or impossible to create finite-element models of all of the components.
“We derive test-based models,” says Allen. “We test
the structure to find its dynamic properties, and then attach that test-based
model to a finite-element model for the rest of the structure. This
idea has been around for some time, but we
have come up with some new ways of assuring that the process works,
even when there are uncertainties in the models and test results.”
His group at Sandia applied
this to weapons systems—in particular, parts supplied by other
sources that weren’t practical to model. Allen is continuing this
work under a grant from Sandia and also exploring other applications.
“Satellite systems present an interesting challenge,” he
says. “There are some systems that, because they’re designed
for zero gravity, can’t be tested on Earth—yet each subcomponent
could be tested on Earth. My goal is to improve these methods so that
they can be used with confidence, even in high risk applications such
as this.”
Allen also plans to continue
an interest he developed in laser vibrometry, a method for measuring
the motion of a structure without touching it. Currently, laser vibrometers
measure a single point at a time. “But you can also sweep the
laser over a surface continuously as you measure,” he says. “It
turns out that the methods I’ve developed for time-varying systems
can also be applied to laser vibrometry, allowing one to measure the
vibration of a surface with a fraction of the time and effort that it
takes using conventional techniques.”
If his theory proves true,
researchers could obtain measurements faster and also could capture
impact events that are difficult to replicate or a transient event like
a force.
In his spare time, Allen and his wife, Melissa, enjoy
spending time with their son, 6, and daughter, 4. A native of California,
Allen also likes to mountain bike, play tennis, downhill ski, play the
piano and edit home videos of his kids.
