Ytterbium fluid-coupled gage

The piezoresistive ytterbium fluid coupled gage is a useful tool to measure the radial stress time waveform in divergent flow fields. Fluid coupling eliminates lateral strain effects shich would compromise the output and eliminates the ytterbium gage hysteresis seen in unaxial strain conditions. A field experiment shows that fluid coupled gages exhibit no serious under-registration effects at the one kilobar stress level and show good amplitude agreement with a radial stress measurement.