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center include examining methods for assessing vibratory power flow in complex structures.
Two other working groups were established that are con- cerned with the measurement of the dynamic system behav- ior, dynamic modeling and condition assessment of station- ary structures such as buildings, dams, bridges and towers. Specifically, these working groups will standardize the termi- nology, measurement procedures and analysis methods nec- essary to assess the dynamic state and condition of stationary structures and to establish criteria and procedures for the timely assessment of such structural systems. Structural sys- tems under dynamic loading and under environmental stress exhibit fatigue damage and aging (e.g., oxidation) over time that, if not properly assessed, can result in structural failure with potential danger to public safety as well as economic dis- locations. These dynamic stresses can be produced by vibra- tion and shock loading whose impact may be direct or indi- rect. Previous assessment methods relied heavily on inspec- tion. However, in recent decades, advances in structural dynamics evaluation/diagnostics methods have provided insights into the assessment, dynamic modeling and current condition of stationary structures that are both sensitive and quantitative. This working group will exploit these structural dynamics evaluation methods to develop standards of struc- tural system condition assessment that can be used to protect the public safety. One new standard, ISO 16587:2004 Mechanical vibration and shock—Performance parameters for condition monitoring of structures, that has been generated by these experts should help the insurance industry assess risk better in insuring vehicles and structures.
The six subcommittees under the auspices of TC 108 each have dynamic programs of work, that are detailed in references 1 and 2, with information also available on the ISO website (www.iso.org). Examples include the work in SC 3 on transduc- er calibration. SC 3 is in the process of developing a series of standards, that specifies the methods for the primary and sec- ondary calibration of shock and vibration transducers under a wide range of environmental conditions. This series of stan- dards should serve as the basis for conducting vibration and shock measurements for all other ISO standards.
SC 5 is involved with machinery condition monitoring and is an example of standardization across major technologies. The ISO Technical Management Board agreed to establish this sub- committee under the auspices of TC 108 due to the predomi- nance of mechanical vibration and rotor-dynamic diagnostic methods in this field. However, in addition to vibration sensors, sensors for thermal imaging, sensors to assess oil contamina- tion, acoustic emission sensors and simple thermometers are widely used to provide clues to the state of a machine. To gener- ate quality technical standards in this area requires in-depth expertise in all the above areas and an understanding of the interplay between different types of sensors.
The current portfolio of TC 108 consists of over 100 inter- national standards. A compendium of many of the older stan-
3,4
dards can be found in the two ISO Standards Handbooks. Those readers interested in more information on TC 108 from an international perspective can contact Bruce Douglas, the Chairman, at bruce.douglas@att.net, or Susan Blaeser, the Secretariat. at sblaeser@aip.org. Those readers interested in
more information on TC 108 from a national perspective can contact David Evans, the U.S. Technical Advisory Group (TAG) Chairman, at dje@nist.gov or Susan Blaeser in her capacity as the ASA Standards Manager.AT
References for further reading:
1 B. Douglas, “International Standardization of Mechanical Vibration and Shock, The Story of ISO/TC 108,” ISO Bulletin (January 2001).
2 B. Douglas and E. Christ, “The Role of Mechanical Vibration and Shock Standards in Workplace Safety,“ ISO FOCUS (2005).
3 ISO Standards Handbook, Mechanical vibration and shock, Volume 1 Terminology and symbols, Tests and test equipment,
Balancing and balancing equipment, Second edition 1995 (International Organization for Standardization, Geneva), ISBN 92-67-10219-2.
4 ISO Standards Handbook, Mechanical vibration and shock, Volume 2 Human exposure to vibration and shock, Vibration in relation to vehicles, specific equipment and machines, buildings, Second edition 1995 (International Organization for Standardization, Geneva), ISBN 92-67-10219-2.
Bruce E. Douglas is the cur- rent Chairman of ISO/TC 108, the international body charged with writing standards in the technical area of mechanical shock and vibration and the condition moni- toring of machines and structures. He is also the owner of Resonance Technologies that specializes in the development of novel structural dynamics diagnostics and control methods and devices. From 1988
through 1999, he was the Director of Research at the David Taylor Research Center (DTRC), the U. S. Navy’s lead labora- tory in naval architecture and the maritime sciences. From 1985 to 1988 he served separately as Head of the Target Physics Branch and the Structural Acoustics Branch at DTRC and from 1965 to 1985 he was a bench scientist at the Marine Engineering Laboratory in Annapolis Maryland. In the area of basic science he isolated three inter-laminar damping mecha- nisms inherent in laminated composites, developing both the theory and experimental evidence to verify their existence and optimize their performance. He has contributed to over 100 technical publications, presentations, standards and patents over his career mostly in the areas of active and passive struc- tural damping and vibration diagnostics and control. He received his Bachelors and Masters degrees in physics from Virginia Polytechnic Institute and State University and a Ph.D. degree in mechanical engineering from the University of Maryland.
52 Acoustics Today, April 2007