| 摘要 |
1,058,986. Measuring internal friction electrically. COMMISSARIAT A L'ENERGIE ATOMIQUE. May 12, 1964 [May 29, 1963], No. 19769/64. Heading G1N. The internal friction of a wire (7), Fig. 1 (not shown), is measured in terms of the energy input required to maintain oscillations of a torsional pendulum the spindle (2) of which is attached to the wire, and carries four arms 3, 4, 5, 6, Fig. 2, the said energy input being controlled by any departure of the amplitude of pendulum oscillation from a required value as detected by pairs of capacitors 20, 21 and 22, 23 which vary the frequencies of respective oscillators 26, 25. The frequency excursions produced in the two oscillators are equal and opposite, and these frequencies individually beat with a reference frequency 31 in a frequency changer 30, the outputs of which are fed to a discriminator 32 which compares the frequencies, and a differential amplifier 37 which receives at 35, 36 a voltage having an amplitude proportional to the difference between the two frequencies. A memory device 40 is provided with the amplifier 37 to store a voltage appearing at 35, 36 for one cycle of the pendulum oscillation, whereby the amplitude of successive oscillations are compared and any difference in amplitude used to control the energy supplied from terminals 42, 43 to coils 16 to 19 which act upon magnets 14, 15 carried by two arms of the pendulum. A meter 48 indicates the energy supplied. The enclosure 8, 9 may be heated to measure the temperature dependence of the internal friction, and the frequency of the pendulum oscillation may be measured to give the Young's modulus of the wire. |
