COMPOSITE FORM AS A COMPONENT FOR A PRESSURE TRANSDUCER

A pressure transducer using as a component for changing shape in response to a change in the pressure being measured a composite elongated body, with specially arranged reinforcing fibers. Such a pressure transducer can use various means for sensing the change in shape of the elongated body, including an optical fiber affixed to the elongated body so as to itself change in length in response to a change in pressure, and having a Bragg grating as part of the optical fiber, with the Bragg grating positioned and arranged so as to convey, in response to an optical signal, information about the change in shape of the elongated body. The elongated body is provided with at least one pair of contra-helically wound reinforcing fibers, which may even be bi-axially braided, and are wound either to amplify the effect of pressure acting on the elongated body or to insulate the elongated body from the effects of pressure and other sources of stress. The reinforcing fibers are embedded in a resin, and in some applications more than one pair of contra-helically wound reinforcing fibers are used, so that the composite body consists of more than one layer of reinforcing fibers. The resulting elongated body is a non-isotropic material and can be disigned to have a Poisson's ratio significantly greater than 1/2, the maximum possible Poisson's ratio for an isotropic material, providing an enhanced axial strain accompanying any radial or circumferential strain. The elongated body can also be designed to have a small Poisson's ratio by using an inner layer and outer layer of contra-helical windings where the reinforcing fibers of the two layers intersect at different angles. Un capteur de pression utilise en tant que composant dont la forme doit changer en réponse à un changement de la pression qu'on mesure, un corps allongé composite doté de fibres de renforcement disposées de manière spécifique. Un tel capteur de pression peut utiliser divers dispositifs pour mesurer le changement de la forme du corps allongé, y compris une fibre optique fixée sur le corps allongé de manière à changer lui-même de longueur en réponse à un changement de la pression, et comprenant un réseau de Bragg faisant partie de la fibre optique, ce réseau de Bragg étant placé et configuré pour transporter, suite à un signal optique, de l'information concernant le changement de la forme du corps allongé. Le corps allongé est pourvu d'au moins une paire de fibres de renforcement enroulées dans le sens hélicoï