By Carolyn Allen, Editor
Finding that key metric that helps you diagnose a problem can be a creative challenge. We are learning that unusual tactics and methods are helpful -- strategies such as sound or light.
One example is diagnosis by sound.
SINGING SCREWS REVEAL SICK STRUCTURES
In 2006, a concrete panel weighing several thousand pounds fell onto traffic in Boston's Big Dig tunnel, crushing a car and killing a motorist. The alleged cause -- and subject of a multi-million dollar settlement -- was faulty epoxy that allowed bolts in the ceiling to wiggle loose.
Mechanical engineer Joe Guarino of Boise State University in Idaho is developing an early warning system to prevent such catastrophic joint failures in the future.
His team listens to the sounds made by vibrating bolts.Their analysis of how these sounds change as the bolts unscrew has revealed certain frequencies in these noises that could be monitored to check the health of bolts in buildings, bridges, and tunnels.
Guarino and his team work on a full-scale structural model made of steel beams and girders connected by bolts. They tap the structure with a hammer, causing it to vibrate. The sounds made by the vibrating bolts are recorded by an electronic stethoscope, similar in design to the stethoscopes used by doctors. Then the engineers unscrew the bolts a bit, tap the structure again, and listen for changes in the sounds. "Any slight relaxation in a joint can change the way it vibrates," says Guarino.
Using a pattern detection technique called the continuous wavelet transform, the team can pick out which ranges of frequencies change the most. Their results suggest that the signatures of unscrewing may be found in certain mid-to-high frequencies.Guarino hopes to eventually take it into the field to check for bolts that are vibrating loose or degrading through exposure to the elements. "If we're successful, this could lead to implanting permanent, inexpensive accelerometers that could monitor joints continuously," says Guarino.
SUMMARY
Creative strategies are tested in the lab before taken to the field...but often it is a field worker who notices anomalies that can be the crux of such innovative research. Our senses are here for a reason...and when we rely on ALL of our senses, and trust our observations, we are on the way to creating new approaches to old problems.
Metrics are measurements that can be identified consistently and that have a direct connection to a problem or solution. Metrics are things such as percentages, or colors, or keywords or the timing of an action. They are bellwethers of change.
What metrics do you pay attention to as signals?