Abstract: A biaxial capacitance strain transducer in the form of a laminated structure defining two capacitance strain transducers in orthogonal orientation. Each capacitance strain transducer comprises driven capacitance plates which are excited by an oscillator and a sensing capacitance plate disposed in spaced parallel relation to the driven capacitance plates. A shutter mechanism in the form of a pair of apertured plates is provided between the driven plates and the sensing plates. The ends of the apertured plates extend out of the laminated structure and are attached to the surface wherein strain is to be measured. Strain will produce relative displacement of the apertured plates, resulting in variation in the capacitive coupling between the sensing and driven plates through the apertures. This differential capacitance, which is thus related to the strain to be measured, is detected and measured by suitable electronic instrumentation.

Abstract: A hydraulically actuated collet type grip with an elastic support structure to allow for the axial bending needed to compensate for diametral dimension changes in the specimen gage section to be accomodated within the grip rather than within the tubular specimen. The tabbed end of the tubular specimen is gripped in the annular region of the loud transfer section of the collet. Load transfer is achieved by normal pressure on the collet and the frictional interface between the collet and the bonded end tabs on the specimen.