ISO 18437-5-2011 pdf free download

ISO 18437-5-2011 pdf free download.Mechanical vibration and shock — Characterization of the dynamic mechanical properties of visco-elastic materials — Part 5:Poisson ratio based on comparison between measurements and finite element analysis
Vibrations et chocs mécaniques — Caractérisation des pro priétés mOcaniques dynamiques des matériaux visco-elastiques — Partie 5: Nombre de Poisson obtenu par comparaison entre les mesures et I ‘analyse par éléments finis.
3.6
Poisson ratio
ratio of transverse strain to the corresponding axial strain resulting from uniformly distributed axial stress below the proportional limit of the material
(ISO 17561:2002(111. 3.1.1J
3.7
shape factor
ratio of the area of one loaded surface to the total force-free area in a sample for compression or tension test with bonded ends
4 Background and measurement principles
It is very difficult for numerical analysts to select the Poisson ratio properly in linear FEM analysis The reason is that the Poisson ratio of visco-elastic materials, which is known to be close to 0,5, is rarely provided by the material manufacturers while the computation results are extremely sensitive to the Poisson ratio at values neighbouring 0,5. This part of ISO 18437 uses a quasi-static method for determining the Poisson ratio of a visco-elastic material or a porous-elastic material The method is based on the relationship between the compressional stiffness. Young modulus, Poisson ratio, and shape factor obtained from axisymmetrical finite element calculations on a disc-shaped sample under static compression. The relationship accounts for the fact that the disc sample bulges sideways when compressed between two rigid plates on which it is bonded. A compression test is used to measure the stiffness of the sample.
The conditions for the validity of the estimation methods are:
a) linearity of the vibrational behaviour of the isolator;
NOTE 1 This Indudes elastic elements with non-linear static load-deflection characteristics where the elements show approximate linearity in vibration behaviour at a given static preload.
b) interfaces of the vibration isolator with the adjacent source and receiver structures can be considered as surface contacts;
c) no interaction between the isolator and the surrounding fluid (usually air) medium.
NOTE 2 This condition Is typically fulfilled at frequencies less than 100 Hz for isolators made from open-cell porous- elastic materials (eg. foams)
The Poisson ratio may also be determined by measuring other elastic constants such as complex bulk and shear modulusPi. However, experimental difficulties may exist. Alternatively, a direct measurement of Poisson ratio may be possible using a laser vibrometer to measure the lateral displacement.ISO 18437-5-2011 pdf free download.