Abstract: A capacitive extensometer has an extensometer frame formed of a pair of arms having first ends with specimen contacting members and which are connected together about a hinge axis at second remote ends. The specimen contacting members engage the surfaces of a specimen to be tested. A capacitive type sensing arrangement is mounted on the arms, and is used with conventional circuitry for determining arm motion. The sensing members are located to insure adequate output, and can be located to the exterior of the periphery of the extensometer arm assembly. The ability to mount the capacitor sensor appropriately, while obtaining a relatively large output signal enhances the operability of the extensometer.

Abstract: A capacitive extensometer has an extensometer frame formed of a pair of arms connected together about a hinge axis at first remote ends, and having second ends which include specimen contacting members for engaging the surfaces of a specimen to be tested. A capacitive type sensing arrangement is mounted on the arms, and is used with conventional circuitry for determining arm motion. The sensing is made so that it can be compensated for nonlinearities and minimizes undesirable extraneous effects by utilizing concave and convex shaped mating surfaces on the sensing elements. The ability to mount and protect the capacitor sensor approximately, while obtaining a relatively large output signal enhances the operability of the extensometer.

Abstract: A self-supporting extensometer for use with rectilinear specimens has one arm that contacts a specimen edge on two points that are spaced apart in a longitudinal direction of the specimen, and a second arm which engages an opposite edge of the specimen at a single substantially point contact under a spring load urging the arms together. The specimen contact arms are notched to receive edges of the rectilinear specimen. The second specimen contact arm has single point contact and has a curved surface which engages a side edge of the specimen so that contact with the specimen is at a point. The support assembly includes a releasable hold-down or clamp spring that bears on the surface of the specimen opposite from the extensometer to clamp the extensometer in place. The spring loading of the extensometer arms and the hold-down spring supports the weight of the extensometer directly on the specimen.

Abstract: A capacitive extensometer utilizes an extensometer frame having a pair of arms connected together about a hinge axis at first remote ends, and having second ends which include specimen contacting members for engaging the surfaces of a specimen to be tested. A capacitive type sensing arrangement is mounted on the arms, and is used with conventional circuitry for determining arm motion with respect to each other. The sensor is made so that it can be adjusted, and also can compensate for nonlinearities by utilizing differently shaped elements. The ability to mount and protect the capacitor sensor appropriately, while obtaining a relatively large output signal enhances the operability of the extensometer.