| 摘要 |
1,189,127. Electric extensometer. COURTAULDS Ltd. Aug. 4, 1967 [Aug. 5, 1966], No. 35110/66. Heading G1N. An extensometer producing a voltage proportional to length variations of a test article has the change in output voltage due to a selected percentage change in length, adjustable to a desired value. The end of a filament undergoing a tensile test is attached to the wiper 1 of a potentiometer RV1 which has potentials E1, E2 applied to its opposite ends, the potential E2 being controlled by amplifiers A2, A4 to produce zero voltage on the wiper when it is in a position 1b corresponding to the initial length of the filament, E2 being thereafter constant while the wiper follows extension of the filament (position 1c) and applies a voltage to a capacitor C2. The voltage of C2 is subsequently compared at 8, by changing over switch G1, with the potential of a wiper 9 of a second potentiometer RV2 driven by a motor which stops whenthe output of the comparator 8 is zero. The wiper 9 is coupled to an indicator drum calibrated in % extension. The filament is pretensioned to remove crimps, &c, thus moving wiper 1 from a position 1a to the starting position 1b the switch W1 being in the position shown to produce the value of E2 required to give zero volts on the wiper at 1b, the capacitor C1 serving to maintain the value of E2 when switch W1 is opened. A circuit A revives the potential E1 from a stabilized voltage E3 applied to the second potentiometer RV2, and a circuit B defines the output sensitivity of the potentiometer RV1, both circuits having adjustable resistors R1, R2, R3, R4 to vary the range and sensitivity of the extensometer. |
