PROGRAMMABLE SYSTEM FOR THE MEASUREMENT OF THE SHEAR MODULUS AND INTERNAL FRICTION, ON SMALL SPECIMENS, AT VERY LOW FREQUENCIES

J. Woirgard; Ph. Mazot; A. Rivière

doi:doi:10.1051/jphyscol:19815175

Numéro		J. Phys. Colloques Volume 42, Numéro C5, Octobre 1981 ICIFUAS-7 Seventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids


Page(s)		C5-1135 - C5-1140
DOI		https://doi.org/10.1051/jphyscol:19815175

ICIFUAS-7
Seventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids

J. Phys. Colloques 42 (1981) C5-1135-C5-1140
DOI: 10.1051/jphyscol:19815175

PROGRAMMABLE SYSTEM FOR THE MEASUREMENT OF THE SHEAR MODULUS AND INTERNAL FRICTION, ON SMALL SPECIMENS, AT VERY LOW FREQUENCIES

J. Woirgard, Ph. Mazot et A. Rivière

E.N.S.M.A., Laboratoire de Mécanique et de Physique des Matériaux, E.R.A. CNRS n°123, 86034 Poitiers Cedex, France

Abstract
A programmable system has been designed for automatic measurement of the shear modulus and internal friction, as a function of frequency, in a wide frequency range (10^-7 - 100 Hz). The system incorporates a low cost micro-computer (Rockwell- AIM65) and performs driving signal control, response signal conditionning, analog to digital conversion with a high sampling rate (up to 2 Mhz) and digital recording in static RAM memories (16,384 twelve bits words per cycle). Before internal friction (phase lag) and shear modulus (amplitude) measurements, the recorded signal is converted into a fixed frequency signal (15 Hz) and filtered thanks to a high order, high stability analog filter. Programmed in a easy to use language (Basic), the system has been proved to be very suitable for accurate measurements on small sized specimens (10 mm in gauge length) and to reduce the influence of external vibrations.