 | Computer Modeling and Simulation ASEC Room 535 Dept. of Civil Engineering The University of Akron Akron, OH 44325-3905, U.S.A. Tel: 1-330-972-2683 Email: jjramsey_6x9eq42@yahoo.com |
BACKGROUND
Initially, my major was in Mechanical Engineering. I obtained my Bachelor’s Degree from California State University, Fullerton in 2002, graduating Magna Cum Laude. I had later moved to Ohio, and after a while decided I needed to go back to school, and got my Master’s Degree,also in Mechanical Engineering, here at the University of Akron, in 2006. As one could gather from the abstract of my Master’s Thesis, the work that I do under Dr. Pan is quite different from my work as an Mechanical Engineering major.
However, one of my hobbies has been “playing” with computers, especially Unix-like systems such as Linux or Mac OS X, and this has been useful for working with the computers at the Ohio Supercomputing Center, as well as those at the Army Research Laboratory’s MSRC. Learning computation tools, such as the well-known Matlab, and the lesser-known R, has also been something that I have largely done on my own. Curiously enough, it was thisinterest in computers that got me recruited as a member of Dr. Pan’s team.
As part of the work that Dr. Pan has been doing with the Army Research Laboratory (ARL) on quantum dots, I have been interning at the branch of ARL in Aberdeen Proving Ground,
Maryland during the summers of 2006 and 2007. It is at ARL where I began to learn about atomistic simulations. Some of the results from this work will bepresented at the 9th U.S. National Conference on Computational Mechanics.
Master’s Thesis Abstract
Research has been ongoing into systems that use sensors embedded in the aircraft to continuously monitor damage within it, e.g. fatigue cracks, corrosion, etc. One example of such a system is embedded ultrasonic structural “radar” (EUSR), in which an array of piezoelectric wafers bonded to a thin panel (which may, for example, be part of an aircraft’s skin) transmits pulses of Lamb waves into the panel and receives echoes from pulses reflected from damage in the panel. These systems are meant to operate while the aircraft is in service, including the times when it is in flight, but there appears to be little research into how well these systems perform in service conditions. In particular, there appears to be no research on how vibration from airflow across the aircraft skin may affect a system like EUSR.
To test the effects of such airflow, a test specimen was placed in a wind tunnel. The specimen was an aluminum panel with a wooden frame around its edges to protect its underside from wind. In the first phase of experiments, two piezoelectric wafer transducers were glued to its underside. One transducer sent Lamb wave pulses while the other received them. In the second phase, one transducer was removed and replaced with a cut in the panel, while the other was set to both transmit pulses and receive echoes. For both phases, the signal from the transducer receiving the pulses was recorded as the wind speed in the tunnel varied.
The shape of the pulses from the receiving transducer remained intact but rode on lower frequency carrier waves whose amplitudes increased with wind speed and could become large enough to saturate a typical data acquisition system. This problem was masked in the second phase of experiments by the fixed internal resistance of the signal generator, which inadvertently acted as a high-pass filter. However, the first phase indicated that the kind of filtering done by the signal generator would not likely work at high speeds. Finding a method of filtering the lower frequencies while avoiding saturation is a possible topic for future work.