| 摘要 |
<p>988, 684. Measuring electrically. WESTERN ELECTRIC CO. Inc. Aug. 3, 1961 [Aug. 5, 1960], No. 28270/61. Heading G1N. [Also in Division H1] A piezo resistive semi-conductor strain gauge is attached to a bridge member which is in turn attached to the specimen whose strain is to be measured in order to partially compensate the non- linear strain-resistance characteristics of the gauge. Fig. 1 shows a strain guage 10 attached to a bridge 14 to measure the strain in a specimen 24, the gauge being prestressed by attaching it to the bridge member while the parts are at a temperature differing substantially from that at which the device is to be used, e.g. for measuring tensile stress an N-type semi-conductor can be attached to a duralumin bridge at a temperature of 125‹C. for use at room temperature, or to a molybdenum bridge at 780‹C. for operation at temperature of several hundred degrees C. Alternatively for compressive strain measurements a P-type semi-conductor may be attached to a duralumin bridge at temperature of minus 100‹C. for use at room temperature. Fig. 2 shows an arrangement in which a bridge 16 imparts a non-linear transfer characteristic between the strain in the member 24 and the strain transmitted to the gauge 10. The non- linearity in the transfer characteristic being arranged to be opposite in effect to the non-linearity of the gauge itself giving an overall linear characteristic. The gauge may also be prestressed as described with respect to Fig. 1. In addition two strain gauge elements of opposite conductivity type may be attached to the bridge member and arranged in adjacent arms of a bridge circuit to reduce the compensation required. Fig. 6 shows an arrangement in which gauges 10 connect in adjacent arms of a bridge circuit to measure the strain in specimen 60. The non-linear response of piezo resistive strain gauges with temperature variations may be compensated by the method described in Specification 950,937.</p> |
