ESQUISSE DES BASES THEORIQUES DE DE L'ESSAI DE VIBRATION AU SOL (OUTLINE OF THE THEORETICAL BASIS FOR VIBRATION TESTS ON THE GROUND),
Abstract
The structure, assumed to be linear, is defined on the basis of an 'associated conservative structure' (AS) obtained by disregarding any internal viscosity. The natural AS modes are taken as reference modes. The object of a ground test is to ascertain these modes, together with the overall characteristics associated with them: natural frequencies, generalised masses, generalised viscosities of the real structure. The response to a harmonic excitation is examined and it is shown that a necessary preliminary operation consists in matching appropriate exciting forces by suitable choice of their positions, their relative amplitudes and their common frequency. This done, the structure must respond as a system with one degree of liberty defining the mode sought. The overall characteristics are easily deduced: the determination of the generalised viscosities is based on an elementary theory which obviously introduces the dry friction affecting the units of the system; measurement of the generalised masses is made by two methods, the theoretical justification of which forms the subject of numerous reports. The response of the structure to a percussive or a plucking excitation is also discussed. In this case, it is primarily the theory of the separation of the damped harmonic components which justifies the practical use of the process for determining or checking overall characteristics. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1958
- Accession Number
- AD0661939
Entities
People
- R. Mazet
Organizations
- AGARD