Effect of High Pressure On a Strain Gauge Load Cell

A load cell employing foil strain gauges is described for measuring small uniaxial loads (5×104 to 2×106 dynes) applied magnetically to develop bending stresses in crystals under hydrostatic pressures up to 15 kbar. Two calibration methods of direct loading at pressure were used—a magnetically operated plunger and dead weight loading. It was established that the change in gauge output (the ``pressure effect'') during increase of pressure at no-load is in keeping with previous work. However, the gauge factor, as determined by the load cell response after balancing at pressure, decreases with increasing pressure. For the strain gauges used here, the decrease is approximately linear and at 10 kbar is as much as 20%.