In the recent past, the manufacturing sector was the major constituency in the development of technical standards for mechanical vibration and shock. Now, there exists a wide and growing diversity of interests between nations and within nations, e.g. high versus low population density nations, high GDP versus relatively low GDP nations, predominantly natural resource and farming versus industrial economies. With this wide diversity, the impact of international technical standards in mechanical vibration and shock is being more deeply felt by a wider segment of society than in the past. The market for standards in mechanical vibration and shock has grown significantly within the past ten years and the high rate of growth should continue for the foreseeable future as macro forces in society dictate increased awareness of the environment, public safety and globalization of trade.

　

Within a nation there exist competing constituencies so that a national consensus on a standard may not be obvious or easily determined. Public safety and the environment demand the interest of Government. Fair business practices demand the involvement of the manufacturing, Government and consumer segments of society. Each constituency brings a fresh perspective to the process of standards development and the process of the development of fair standards requires broad representation of a diversity of positions. A fair standard is written in such a way as to allow the greatest flexibility in compliance, to promote consistency with other related standards and to minimize its implementation costs. It should avoid the use proprietary intellectual property, as that would give an unfair advantage to a select few. In developing fair technical standards, it is important to realize that the viewpoints of all national and economic constituencies are valid and, hopefully, represented in the process.

　

Although international standards do not carry the weight of law, they have the potential to influence the language, interpretation and direct extent of law. Technical standards are often written into contracts to monitor acceptance and performance. In other words, they have a major impact on the economy of a nation in terms of jobs, world trade, national competitiveness and GDP. A brief summary of the impact of the major markets directly influenced by standards generated under TC 108 auspices is listed below.

　

Vibration transducers are the means by which vibration and shock is sensed and measured. As such, any quantitative measures of vibration and shock are fundamentally linked to the design, calibration and mounting of these sensors. ISO/TC 108/SC 3 is responsible for developing international standards detailing the calibration of vibration and shock transducers from the most basic primary calibrations conducted by national metrology laboratories to field calibrations conducted under a variety of environmental conditions. In addition, it has developed standards for the mounting of transducers as well as specification items that must be provided by the manufacturer to the user. In addition to transducers, SC 3 is responsible for developing standards for general vibration instrumentation. Currently, a standard for the human vibration meter is under consideration. These standards provide the basis for conducting vibration and shock measurements and for building meaningful comparison databases used in condition monitoring of machines and structures. As such, they are fundamental to the wide spectrum of work items under TC 108 jurisdiction. The business base for these standards include not only transducer and instrumentation manufacturers but also users who account for the full range of constituencies listed above.

　

It can be argued that machinery makes society run. From power generation to engines for vehicles to hand tools to pumps, rotating machinery is basic to life in the twenty-first century. Manufacturers, suppliers and operators as well as the owners of machines have an interest in their performance and reliability. The condition or state of a machine is, to a great extent, determined from its vibration signature, e.g. the measurement and evaluation of the vibration of shafts and bearings. International standards for the determination of the acceptability, balancing, serviceability and condition monitoring of machines are primarily being developed in SC 1 , SC 2 and SC 5 of ISO/TC 108.

　

Motorised vehicles are pervasive today's society. Land vehicles ranging from cars to trucks to railroads to farm machinery to construction vehicles, are involved in moving all goods critical to society from the supplier to the user as well as construction of a nation's infrastructure. Ships move basic goods between continents and are especially critical to the movement of raw materials. Aircraft move smaller high-value goods and equipment over long distances. All types of vehicles transport people. As such, the ride must be safe and comfortable. The TC 108 working groups along with SC 2, 3, 4 and 6 are primarily concerned with developing standards for dynamic design, ride comfort and crash worthiness of all types of land, sea and air vehicles. These standards outline the types of vibration and shock measurements, analysis procedures and evaluation criteria required to adequately assess vehicles from the viewpoint of fundamental design under dynamic loading to ride comfort to vehicular response under high impact shock.

　

TC 108 working groups and its subcommittees, primarily SC 2 and 4, are concerned with the dynamic response of a wide range of stationary structures ranging from buildings to sea platforms to large civil structures such as bridges, dams and tunnels. This interest extends to the assessment of basic design under dynamic loading to condition monitoring under the cumulative dynamic stress damage of service. Stationary structures can be subject to wind loads, wave action, dynamic loading produced by man e.g. construction, road noise and vibration, and seismic activity primarily in the form of earthquakes. These dynamic forces have great dynamic range and, in single events, have produced drastic loss of life and economic dislocation of historic proportion.

　

Dynamic environments as well as increasing human activities using machinery in and outside the work environment means human exposure to mechanical vibration, shocks and motions. Vehicles (air, land and water), machinery (e.g. used in industries and agriculture) and industrial activities (such as piling and blasting) expose people to periodic, random and transient mechanical vibration which can interfere with comfort, activities and health and safety. Depending on the vibration magnitude, frequency, time duration, direction as well as posture of the person exposed, mechanical vibration may cause health and safety risks, effects on human performance or reduction of comfort of people in buildings or in vehicles (transportation systems). TC 108/SC 4 is concerned with developing technical standards that measure, evaluate and assess human exposure to vibration and shock in various critical environments. Interested parties of the standardisation work are safety engineers, labour inspectors, designers and manufacturers of machinery as well as of personal protective equipment, governmental authorities, testing laboratories, certification bodies, medical advisors/doctors, scientists as well as consulting engineers. These people may be involved in occupational as well as in environmental protection activities. Standards generated by ISO/TC 108/SC 4 provide the basis either to enable legislation to refer to the standards or to enable standards writers to establish specific measurement and evaluation methods which serve these legal requirements. Standards of ISO/TC 108/SC 4 establish the relationship between risks and possible hazards. This enables responsible authorities for occupational safety to set legal requirements for vibration prevention.

Additional aspects are:

　

Much of the world's engineering infrastructure has exceeded or is in the process of exceeding its design life. The long-term integrity of engineering assets depends fundamentally on the quality of their maintenance. Maintenance costs run into countless billions of dollars per year. ISO TC108/SC 5 aims to set standards to improve the supply-security and the effectiveness of maintenance practice through the issuance of world-class standards in asset integrity and condition monitoring and diagnostics.

　

There is a wide gulf between the stated maintenance approach and actual practice. A "maturity continuum" of maintenance strategies is illustrated in Table 1 . The oldest maintenance strategy was simply to fix parts when they fail. The 1950s saw the increase of preventative maintenance. The 1970s saw the introduction of condition-based maintenance. The current cutting edge is an integrated approach that includes an optimization of both operations and maintenance. Procedures leading to the cost-effective elimination of maintenance are also emerging. These changes in maintenance practices are being accelerated in all industries. At the same time, down-sizing of companies has resulted in contracting out of many functions such as detailed system design and equipment maintenance. Consulting organizations often do not have the expertise needed to undertake the tasks needed to optimize performance. This situation puts assets at risk, often causing vast environmental damage. It is therefore crucial that the worlds' best practice in this vital area be encapsulated as international standards so that practitioners can follow appropriate guidelines and avoid such catastrophic consequences.

　

　

　

Maintenance and operation of assets is an immediate problem for aircraft, defense, process, manufacturing, oil and gas, power generation and water industries. There is a crucial need for standards concerning the assessment and extension of the residual life of aging structures and machinery. Whilst safety is a primary issue, maintenance services have to deliver "smarter" outcomes to remain competitive in global markets and to minimize environmental damage. Failure prediction is also a key requirement of maintenance service providers.

　

ISO TC108 has therefore formed SC5 with the title, "Condition Monitoring and Diagnostics of Machines" and the following scope:

　

Vibration generators are primarily used as test and diagnostic equipment and are used for environmental testing; investigation of dynamic behaviour of structural systems; system diagnostics; calibration, oil exploration and geologic mapping of subsurface structures etc. ISO/TC 108/SC 6 has the responsibility for generating standards in this growing and fundamental area

　

Currently there are about 20,000 electrodynamic vibration generation systems in use for dynamic environmental testing. Of these systems, most are used to produce sinusoidal vibration environments. The rest are used to produce random vibration environments and impulse (shock) environments.

　

The customers can be divided into the following main categories:

　

　

Growth is estimated to be moderate for each category with a growth rate approximately 5 percent annually for the next three years. Total volume of all types of vibration generation systems amounts to of the order of $ 500 millions to $ 1 000 millions per year world-wide. Total employment (employees) for the business of the vibration test equipment can be estimated approximately at 5 to 7 thousand.