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inclusive as possible, thus encouraging product innovation. Good standards should account for the realities of life in a wide range of economic circumstances without being unduly complicated and burdensome to apply.
In the near future, ISO/TC 108 is going to re-examine standards associated with the basic physics of the mechanical vibration and shock response of complex systems and the art and science of vibration and shock measurement. By empha- sizing these areas, it is hoped that this committee can provide tools that can be consistently applied to provide meaningful measurement methods, repeatable measurement results, and consistent databases with known uncertainty that are the backbone for setting performance and condition monitoring levels for acceptance, prognosis and assessment purposes.
In addition to measurement practices, this technical com- mittee will undertake new initiatives in defining appropriate vocabulary and symbols used in the vibration and shock com- munity. The proliferation of new technology in this area is pro- ceeding at such a rapid rate that inconsistencies in technical lan- guage are starting to be a problem. Precise language usage is fun- damental for both public law and contract compliance. It is a prerequisite for providing meaningful guidance to protect pub- lic safety, the environment and culture.
One working group has been established in the areas of signal processing of vibration and shock measurement time- histories. This group is charged with generating internation- al standards to classify vibration and shock signals as well as analyze and identify feature sets from such measurements. It is anticipated that these standards will assist the machine condition monitoring community by improving the quality of the databases by allowing them to be used for detailed comparison purposes and precursor identification. For example, a recent standard, ISO 18431-2:2004 Mechanical vibration and shock—Signal processing—Part 2: Time domain windows for Fourier Transform analysis, generated by this working group standardizes the algorithm for time domain windows for Fourier Transform analysis. This standard, if widely applied, should result in data sets that can be com- pared more exactly for examining change in system dynam- ics over time, a critical issue for predicting failure.
Another working group is concerned with developing stan- dards for vibration and shock data acquisition. Its scope is to identify a set of key parameters that adequately describe the basic conditions of a vibration measurement for the purposes of allow- ing the technical community to efficiently compare measure- mentsandbuildmeaningfuldatabases. After completion of this task, its scope will broaden to shock measurements. These standards will serve as the anchor for a planned compendium of standards for making high-quality vibration measurements.
Two working groups have been formed to standardize structural dynamics analysis and measurement tools for assessing the dynamic behavior and state of complex struc- tural systems. These tools are primarily based on the applica- tion of a known force and the subsequent measurement of the amplitude and phase response at critical points in the sys- tem. Future project areas might include measurement meth- ods for mechanical mobility, modal analysis, structural inten- sity, wave-number analysis (spatial array processing) and structural damping evaluation. Current areas under study
condition monitoring of machines (SC 5)
vibration and shock generators (SC 6).
Most technical committees within ISO are assigned
along product lines and have a very strong manufacturing component in their constituency. TC 108 is somewhat unique in that it spans many constituencies. This is due to the fact that its standards directly impact human health and safe- ty, the environment, as well as the design of vehicles, machines and national infrastructure, manufacturing, trade, jobs and the economy in general. Standards written by this Technical Committee can, and have, directly influenced who gets a shipbuilding contract or which machine tool gets to market, as well as which machine goes into a vehicle or build- ing. These standards can even have a great impact on the preservation of cultural monuments and historical buildings, an issue of great current interest in Europe. The main impact of TC 108 standards is to broadly influence customers and markets by specifying acceptable vibration and shock levels and to mitigate downside risk of failure in machines and structures.
This is one of a few ISO Technical Committees that can be said to impact the overall quality of life of nations. As a result, the member countries send experts that reflect a wide range of experience. Government representatives provide expertise on the environment, the consumer, human health and human safety from the user perspective. Experts from the manufacturing and design communities are concerned with customers and the marketplace. Those from academia bring expertise in the basic sciences. This mix of experts tends to act more in the interest of society at large, since con- sensus building is a strong aspect to reaching the final stage of the process, an international standard. The diversity of opinion and perspective in generating a standard is its pri- mary strength and measure of its quality since technical stan- dards are voluntary and primarily reflect the wisdom and reputation of participating individuals and organizations.
Future directions of ISO/TC 108
As we enter the twenty-first century, the world is experi- encing a revolution as profound as the industrial revolution before it—the high technology, information revolution. Like the industrial age, the high tech age is having a major impact on all aspects of society. However, our Achilles’ heel is the inherent complexity in high tech advances and the law of unintended consequences. The technology behind many of these significant developments is understood only by a select few. The interactions between components of complex sys- tems are often poorly understood and a need for robustness and real-time monitoring has become a critical concern as our reliance on such systems increases. This issue, more than any other, drives the need for condition monitoring stan- dards and explains the ISO decision to upgrade the visibility of SC 5 within TC 108. As a result, the need to rapidly incor- porate new technologies into the TC 108 work agenda has become a paramount concern in order to keep these stan- dards meaningful and relevant to the user community.
The main challenge in TC 108 is to develop quality stan- dards that are based on a solid scientific foundation and yet have met some test of time. These standards should be as
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