TRANSDUCERS FOR SUB-MICRON DISPLACEMENT MEASUREMENTS AT CRYOGENIC TEMPERATURES

This paper deals with recent developments of extensometers working in cryogenic environments down to 4 K capable to transfer accurate, high resolution, and reproducible signals for a variety of engineering measurement tasks such as tensile, fracture, compression, fatigue, flexural, and component tests. Based on strain gauge technology it was possible to manufacture extensometers with resolutions lower than 20 nm. The extensometers foreseen for uniaxial tensile tasks were designed as a twin extensometer system firmly attached onto the specimen and providing for bending during loading by averaging the signals either via software or by special electrical wiring. In particular, for structural component tests, different types of extensometer designs were represented. With the production of a new series of small, low weight, worldwide first twin extensometer system of ∼ 0.5 g mass it was possible to resolve the local strains of fragile Nb3Sn wires. Besides the measurement of distances, it was possible to develo...