Vibrations of industrial structures

This article presents strategies for controlling vibration at different stages in the development and life of an industrial plant or product. Five qualities, both technical and human, can be affected by vibration problems in an industrial context:

• safety or at least operational security ;

• peace of mind;

• regularity of production ;

• the service life of the structure and its components ;

• endurance and health of operators at the workstation.

These qualities, which must be quantifiable, need to be taken into account right from the design stage, during development and during operation of the structure, right up to its overhaul or retirement. It is possible to estimate the technical share and corresponding cost attributable to undesirable vibratory effects of a structure's overall operating balance.

Examples of concrete interventions to control vibrations are presented in paragraphs 3 to 5 . There could be many more, as vibrations are ubiquitous. Indeed, any fluctuation in load, flow or speed, or any irregularity in the movement of parts of a plant, is a source of vibratory excitation for neighbouring structures, which is all the richer and more intense the faster the fluctuation. Brief shocks, for their part, can excite all the natural frequencies of a structure.

Structural responses, which are useful to know, depend on the position of the natural frequencies in the spectrum, but :

• on the one hand, the...