SU563655A1 - Tensoresisting instrument for measuring static magnetostriction - Google Patents

Description

It is connected to the input of the magnitude of the reference resistor through the control terminal.

The drawing shows a block diagram of the proposed device.

The device contains the source 1 of the magnetization field of the sample under study 2, the strain-transducer unit 3 including the measuring bridge 4 connected in series with the strain and balancing resistors (not shown in the diagram) and the DC amplifier 5 or phase-sensitive (depending on the type of current feeding the bridge 4 ), keys 6-9, memory cells 10-12, adder 13 (decisive cascade), control unit 14, adjustable (variable) reference resistor 15 equipped with a measurement result indication block 16, and control generator 17. X pulse c, specifying the time sequence of operation of the links (source 1, keys 6–9, control block 14).

In the initial state, which is established when the instrument is energized or at the end of the measurement cycle, there are no control signals at the generator 17 outputs, and as a result: the keys 6–9 are open, the source 1 and the control unit 14 are turned off. The value of the model resistor 15 (and, accordingly, the output of the measurement result indication block 16) corresponds to the result of the previous measurement (or, in general, iron).

The operator, after an approximate balancing of the strain-reduction unit 3 (the balancing organs and the output signal meter in the diagram are not shown), starts the generator 17 of control pulses — a measuring cycle begins, consisting of a number of repeating cycles, equal to the duration T.

At the end of the first path, at the command of the generator 17, the first key 6 closes: the output signal of the strain gauge unit 3 is recorded in the first cell 10 of the memory. Consequently, with the end of the first cycle - with the opening of the key 6 (we denote this time ti) - at the first input of the adder 13 there is a signal U, due, on the one hand, to the initial unbalance G / 01 of the strain-reducing unit 3, and, on the other hand, the inevitable presence sinusoidal network interference with a period of Tc and amplitude t / n, i.e.

,,.

with.

At the time of the second clock cycle, according to the commands of the generator 17 control pulses:

1. A controlled source 1 of the magnetization field of test sample 2 is started, and the latter is magnetized. The occurrence of this magnetostrictive deformation X of sample 2 is perceived, for example, by one working strain gauge (with a strain gauge 5), which is part of the measuring bridge 4.

2. The third switch 8 is closed, connecting the reference resistor 15, for example, to one of the arms of the bridge 4 and causing the latter to unbalance by an amount proportional to the relative change in the resistance of this shoulder - EYL

After a time sufficient to establish the magnetization and the corresponding striction deformation of sample 2, at the command of the generator 17, the fourth key 9 is closed. At the same time, the output signal of the strain gauge unit 3 "is recorded in the third memory cell 12, the output of which, i.e., the third input adder 13, with the end of the 5 second cycle (with the opening of the key 9) have

U) and ,, + b, T + / „sin 2- JL +

4T-s

+ K, (5l + and + b, T + / C, (S + g „.).

The latter is possible if the duration of the cycle is equal or multiple to the period of the network — the most pronounced — interference, i.e. (where, 2, 3, ...), and if we take into account that

Sm2T: - ± Sin27: CAC.

for any general n.

0 Here biT is the value of the component of the drift zero, linearly varying at the speed b (in the interval of the second and third cycles) at the time of the end of the second cycle; K. - transfer coefficient operating in this cycle

5 parts of the measuring path, equal to the product of the transfer coefficients of the strain-reduction unit 3, key 9, memory cell 12 and the voltage of the measuring bridge 4.

0 At the beginning of the third cycle, the controlled source 1 of the magnetization field of the test sample 2 is turned off and the third switch 8 is opened, removing the effect of the reference resistor 15 on the bridge 4. At the end of this cycle

5 (at the end of the transient processes caused by the indicated commutation) the second key 7 closes - a “memorization of the output voltage of the strain gauge unit 3 of the second cell 11 of the memory occurs. As a result, with the end of the third cycle (with the opening of the key 7) at the second input and output of the adder 13 have

 z and ,, + 2b, T -f and „sin 27Г А ±

Tc

 f / f + 2b, t

yf) + 4M

; (/ C:

- ATiATj; (5X-j-Sji),

Claims (1)

where / (s is the transfer coefficient of the adder 13. With the start of the fourth cycle (as in the second cycle), the source I field turns on and the third key 8 closes, and also (unlike the second pact) the 1 CL closes for some time control element 14, which, under the influence of the output signal of the adder 13, changes the value of the model resistor 15 and thereby sets the new value e0 so that (.SA + EOZ) (5A, + eoi), and with a change in the value of the resistor 15 there occurs a corresponding change in the indications of the result indication block 16 measurement. At the end of this When the transients are completed in the device, caused by switching and changing the value of the reference resistor 15, the fourth switch 9 closes, connecting the output of block 3 to the input of the third cell 12 of memory, the output of which at the end of clock cycle (after opening the switch 9) is i / f) f / P + 6, r +, p. + sJ, where 2 is the zero drift velocity during the fourth and fifth cycles. In this cycle, the information effects (magnetostriction and reference resistor) and theisotransformation unit are again removed, and the output signal of the last Lffi U + 2b2T, due to non-informational components (drift and network interference), is recorded, as in the first cycle, into the first cell 10 memory Consequently, at the output of the adder 13, the signal .Suf-- K, K (SK + ,,), which is an absolute value less than the signal, also acts on the output of the last in the fourth cycle. The operation of the device in the seventh, eleventh, fifth, and so on steps proceeds in a manner similar to the considered processes one third of its tact, and in the ninth, thirteenth, in the seventeenth, etc., in a manner similar to the first and fifth acts. In all the even-numbered cycles, beginning with the fourth, the processes are also repeated. The measurement cycle is continued until the forked t-th signal at the output of the adder t / l / C, (SX + s ,,) e is set equal to zero, which the operator reads as a result of the steady (unchanging) readings of the block 16 measurement, while the measurement result will be I -eoi / S, i.e., completely (both in sign and magnitude) is determined by the magnitude of the model effect eot, the accuracy of which is quite high to be performed much easier than the accuracy of the myo-element measuring path. After receiving the measurement result, the operator turns off the generator 17 of control pulses, and the device is reset. Claims A strain gauge device for measuring static magnetostriction, containing a controlled source field, a strain gauge unit whose output through the first key and memory cell is connected to the first input of the adder, and through the second key and memory cell to its second input, exemplary resistor through a third key connected to one of the inputs of the strain gage unit, and a generator of control pulses, characterized in that, in order to improve the measurement accuracy and spreading the range of measured values The fourth key, the third memory cell and the control unit are entered into the small value area, and the exemplary resistor is made adjustable and provided with a display unit, the third input of the adder through the third memory cell connected in series and the fourth key connected to the output of the strain gauge block The output of the adder is connected to the control input of the value of the reference resistor through the control unit.