Definition of a Dynamic Optical Sensor for Measuring Unsteady Pressures

P. Chapuis; J.M. Maillard

doi:doi:10.1051/jp4:1997334

Issue		J. Phys. IV France Volume 07, Number C3, August 1997 EURODYMAT 1997 - 5th International Conference on Mechanical and Physical Behaviour of Materials under Dynamic Loading


Page(s)		C3-185 - C3-191
DOI		https://doi.org/10.1051/jp4:1997334

EURODYMAT 1997 - 5th International Conference on Mechanical and Physical Behaviour of Materials under Dynamic Loading

J. Phys. IV France 07 (1997) C3-185-C3-191
DOI: 10.1051/jp4:1997334

Definition of a Dynamic Optical Sensor for Measuring Unsteady Pressures

P. Chapuis and J.M. Maillard

Company BERTIN et Cie, Mechanical and Optoelectronic Divisions, 54 rue Pierre Curie, Z.I. des Gâtines, BP. 3, 78373 Plaisir cedex, France

Abstract
This study presents our contribution to defme an optical dynamic sensor. Given that the studies carried out are of an exploratory nature, the first task was to validate the mechanical behavior of the specimen body in the sensor and to check that the signals recorded were reproducible. To subject the sensor to deformation rates of 10 to 10² per second, tests were carried out using the KOLSKY-HOPKINSON apparatus. The results show that specimen body responds in a satisfactory manner. It remains within the elastic zone for the loads exerted and this is consistent with the results of the sizing calculations carried out. It was also possible to verify complete reproducibility of the interferometric signals on the basis of several tests conducted on the same sensor located between two polyurethane sheets. It is also shown that the sensitivity of the standard monomode fiber used in the MACH-ZENDER apparatus is highly dependent on deformation rates. This result leads us to opt for the use of a polarimetric apparatus using birefrigent shaping fibers in order to limit the intrinsic sensitivity of the two-arm apparatus. The fact that the fiber is sensitive to deformation rates does not appear in the bibliographical references. We identified it on the basis of tests on the traction/compression machine by varying the load climb rate and on the basis of HOPKINSON bar dynamic tests.

Résumé
Cette communication présente notre contribution dans la définition d'un capteur dynamique optique. Nous avons tout d'abord valider le comportement mécanique du capteur dans son environnement et nous avons observé la reproductibilité des signaux enregistrés. Pour solliciter le capteur à des vitesses de déformation de l'ordre de 10 à 10² par seconde nous avons réalisé des essais sur le montage de KOLSKY HOPKINSON. Les résultats montrent que la fibre optique dans le montage réalisé (MACH ZENDER) est fortement sensible à la vitesse de déformation. Nous montrons également, à l'aide d'un modèle unidimensionnel du montage de HOPKINSON et de la transformée par ondelettes du signal interferométrique délivré par la fibre, qu'il est possible d'identifier expérimentalement le gain du capteur.