Page 64 - Summer 2015

Obituary | David Alan Bies | 1925-2015
David Alan Bies, a fel- low of the Acoustical Society of America, passed away on April 6, 2015, in Cairns, Australia, ending his six-decade career in the physics of vibra- tion and noise.
Born into a poor blue- collar family in de- pression-era Los An- geles, David worked and saved as a young man to enroll in an undergraduate degree
in the Department of Physics at UCLA. His PhD investigat- ed the puzzle of why sound absorption was so much greater in seawater than in freshwater. Others had suspected chemi- cal reactions, but his experiments with the ionic dissocia- tion of magnesium sulfate proved it and identified a primary mechanism. Along the way, David invented a new technique for degassing seawater that avoided the need to blast it with hazardously loud sirens; his first foray, as he often said, into the world of noise control.
Others followed. His PhD awarded, David left academia for the world of contract research in private industry, helping the US Air Force identify the cause of the combustion insta- bility plaguing early US rocket designs: acoustic vibration in the combustion chambers. Further research led to the design of a silo liner that could reduce the superdestructive vibra- tion of Minuteman missile launches. By way of a side proj- ect, David also invented a way to reliably test missile launch effects in a scaled model silo (hitherto impossible), thereby saving the Air Force millions.
David's international reputation as a noise control expert led Adelaide University's Department of Mechanical Engineer- ing to offer him a senior research fellowship in 1972. The opportunity to research optical holography was a godsend but even greater assets, he found, were the students. Many of David’s PhD students went on to become mechanical engi- neering professors at Australian and US universities.
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At Adelaide University, David was also instrumental in eval- uating the quality of anechoic and reverberant rooms and the introduction of rotating diffusers. He also worked on the noise control of shearing processes in presses and cir- cular saws, the latter by damping the blade. His invention of a hydraulic oscillator became a sonar source, still used by navies today, that fools mines into exploding harmlessly. The same oscillator, hooked up to steel construction piles, proved capable of vibrating them at frequencies sufficient to liquefy soil, allowing the piles to slide into position without laborious pile driving.
It was also at Adelaide University that David and Colin Han- sen coauthored their book Engineering Noise Control, which went on to become an industry standard.
David spent his retirement researching the vibrational characteristics of the human cochlea. He is survived by his daughter, Carolyn.
Written by: Peter McAllister
Postal: 2209 Springbrook Road, Springbrook, Queensland 4213, Australia
Email: pmcallister@bigpond.com
Articles by David Alan Bies
Bies, D. A. (1955). An ultrasonic investigation of a chemi- cal kinetics problem: The dissociation of magnesium sul- fate. Journal of Chemical Physics 23, 428-434.
Bies, D. A. (1961). Effect of a reflecting plane on an arbitrarily oriented multipole. Journal of the Acoustical Society of Amer- ica 33, 286-288.
Bies, D. A. (2004). An experimental investigation of Curle’s theory of aerodynamic noise generation by a stationary body in a turbulent air stream. Journal of Sound and Vibration 278, 581-587.
Bies, D. A., and Hansen, C. H. (1979). Measurements of the radiation impedance presented to a source in a reverberant room containing a rotating diffuser. Journal of the Acoustical Society of America 65, 708-718.
Bies, D. A., and Hansen, C. H. (1980). Flow resistance in- formation for acoustical design. Applied Acoustics 13, 357- 391.
Bies, D. A., and Hansen, C. H. (2009). Engineering Noise Con- trol: Theory and Practice, 4th Edition. CRC Press, Boca Ra- ton, FL.
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