SU1441222A1 - Vibration testing apparatus - Google Patents

Abstract

The invention relates to a testing technique and can be applied in accelerated vibration tests of mechanical products. In order to improve test performance by using the phase shift selection algorithm, which teaches the orthogonality of the eigenmodes of a mechanical system with a distributed system and parameters, into a device containing generator 1, the accompanying filter

Description

ENO

SD

1

2, recorder 4, power amplifier 5, vibrate / er 6, vibration converter 7, product 9, matching amplifier 10, phase detector I1, detector 12 of absolute magnitude, interpolator 13, differentiator 14, null detector 15, counter 16, matching amplifier 17, accompanying filters 3.1-3.N are introduced, vibration transducers 8.1-8.N, computational blocks 18.1-1.N, containing analog multipliers

The invention relates to a testing technique and can be applied in accelerated vibration tests of mechanical products. .

The purpose of the invention is to increase the test performance due to the use of the algorithm for selecting the phase shift tf, which takes into account the orthogonality of the eigenmodes of the mechanical system with distributed parameters.

Figure 1 shows the block diagram of the device; in fig. 2 (a-d) - frequency diagrams of his work; in fig. 3 - “transition characteristic of the phase detector.

The device contains a generator 1, an accompanying filter 2, an accompanying filter 3.1f3.II, a recorder 4, a power amplifier 5, a vibrator 6, a vibration converter 7, a vibration converter 8.1-8.N, a product 9, a matching amplifier 10, a phase detector 11, a detector 12 absolute values, interpolator 13, differentiator 14, null detector 15, counter 16, matching amplifier 17, computational blocks 1B.1-18.i, which include analog multipliers 19.1-19.N, analog switches 20.1- 20.N, multichannel adjustable dividers 21.1-21.N. The device also contains N-input summing amplifiers 22, 23, the source 24 of the reference voltage. The output of the generator 1 through the power amplifier 5 is connected to the input of the vibration torus 6, the output of which

19.1-19.N, analog switches 20.1-20.N, multichannel adjustable dividers 21.1-21.N, N-input summing amplifiers 22, 23, reference source 24 are also introduced. The introduced blocks provide the ability to select a phase shift according to an algorithm that provides the optimal set of resonant frequencies at which the tests are carried out with minimal time. 3 il.

a vibration converter 7 is installed, the output of which is connected through a matching amplifier 10. To the input of the accompanying filter 2. Each computing unit is 18.1-18. and contains a multichannel adjustable divider 21.1-21.Ы, the outputs of which are connected to the signal inputs of the analog switch 20.1-20 .N, vpsod which is connected to the input of the analog multiplier 19,1-19.N.

The device works as follows.

The electrical signal from the output of the generator 1 after the power amplifier 5 is converted by the vibrator 6 into mechanical oscillations, the amplitude of which is stabilized by a compression circuit formed by the vibrator 7 installed at the output of the vibrator 6, a matching amplifier 10, a filter 2, the information output of which is connected to the input of the generator 1 compression unit Accompanying filter 2 for the purpose of selecting the main vibration frequency is controlled from generator 1, in connection with which its control input is connected to the output of a frequency scanner Generator s 1. Vibrating transducers 8.1-8.N installed on the product 9 generate electric signals proportional to the magnitude of the response of the product 9 to the influence applied from the side of the vibrator 6, which after amplifiers 17.1-17, N are fed to the inputs of the accompanying filters 3.I -3, N control inputs that are combined with the analog input of filter 2.

At the output of the switch 20, which is the signal output of the computing unit 18, a voltage is generated corresponding to the value of one term of the function y. (t).

Periodic function) form, N. The output of the first one is summed by W (x;, t) Oj (x;) - 6inrQt + Cf. (O) irf.j ZlWeCKj) of the amplifier 23, whose inputs

 ten

To obtain the control law for the frequency sweep of the oscillator 1, the following initial equation is used, which follows from the theorem on the decomposition of the established oscillations in its own form:

where W (x, t) is the vibration displacement of the tested product at point K; ei (ω) are functions reflecting the dynamic properties of the product on the corresponding eigenmodes of vibration;

B) (K) is the phase shift of forced oscillations in the kth form with respect to vibration action. From the equation, it follows that the phase shift C. (to) between the forced oscillations on the 1st proper form of the tested product 9 and the effect of 25 at the frequency sd is equal to the phase shift between a certain periodic time N U. (t) Zlw (xi, t) cOp (x;)

l: -1t

All computing units 18 are connected to the signal outputs, respectively. The phase shift cpg (co) is generated by a phase detector 11, the signal inputs of which are connected 15 to the single output of filter 2 and the output of summing amplifier 21. After the absolute value is converted to a single-pole view by detector 12, the control signal enters the input of the interpolator 13, which is

20

smoothing voltage spikes when switching to a new own form and then to the sending input of the oscillator frequency sweep speed 1, When Cj (w) 90, the oscillator frequency 1 sweeps at a certain speed proportional to the phase jBoro shift value | 7.1 ( w), i.e., the maximum speed, if (o) is O or)

30 (according to the transient response of the phase detector I, FIG. 3), and a full stop of the frequency sweep of the generator 1 occurs if Cf g- (w) 90,

and the impact on the frequency W.

Dp of forming signals y {(t) for M natural modes of the product, occurring in the frequency range of the test or specified for the test, the device uses the source 24 of the reference voltage connected to the inputs of the computing units 18. Own forms with, (x ) can. be calculated theoretically or previously measured by testing a mockup, since they do not depend on. product dimensions and level, effects, and are determined only by the shape of the product,; boundary conditions; distribution of mass and rigidity. The required voltage value corresponding to the 1st form co. (X) in each computational block 18, through the switch 20, controlled by the counter 16, sets the code of the form number used for the control, is fed to the input of the analog multiplier 19, to another the input of which is supplied with a voltage proportional to the response of the product at the i-th controlled point with a single output correspondingly. accompanying accompanying filter 3,

connected to the signal outputs of all computing units 18, respectively. The desired phase shift cpg (co) is generated by a phase detector 11, the signal inputs of which are connected to the single output of filter 2 and the output of summing amplifier 21, after conversion to absolute value by the detector 12 absolute magnitude, the control signal arrives to the input of an interpolator 13 serving

25

smoothing voltage spikes when switching to a new own form and then to the sending input of the oscillator frequency sweep speed 1, When Cj (w) 90, the oscillator frequency 1 sweeps at a certain speed proportional to the phase jBoro shift value | 7.1 ( w), i.e., the maximum speed, if (o) is O or)

30 (according to the transient response of the phase detector I, FIG. 3), and a full stop of the frequency sweep of the generator 1 occurs if Cf g- (w) 90,

35

From the information outputs of the filters 3, the voltages are removed} proportional to the amplitudes of the responses of the 9, to which are recorded by the multichannel recorder 4, and also fed to

4Q, the corresponding inputs of the second summing amplifier 22, the output of which is connected to the input of the differentiator 14. After the transients, which indicates the establishment of

4g of the amplitude of the induced oscillations on the corresponding 1st eigenform, at the output of the differentiator 14, zero appears, according to which the null detector 15 produces a pulse, transferring the counter 16 to a new state corresponding to the following () eigenvalue. A new form code at the output of counter 16 switches all analog switches 20 in T computing blocks 18 J connecting to the input of the corresponding multipliers 19 new 1 + 1 adjustable parts 21, which leads to the appearance at the output of the first summing amplifier 23

50

55

The new function yj:, (t). The phase detector 1 at the output generates a signal corresponding to the phase shift close to zero, which after the detector of the absolute value 12 and the interpolator 13 is fed to the generator 1 and provides frequency control in the () form.

Claims (1)

Invention Formula A device for vibration tests containing a generator, a power amplifier, a vibrator, a test product, an interpolator, an absolute magnitude detector, a phase detector, a null detector, a counter, a recorder., The main vibration transducer, matching amplifier J accompanying filter, N additional vibration converters, N additional matching devices, N analog switches, main vibration converter is intended for installation on the moving part of the vibrator, additional vibration transducers are intended for installation on the tested product, the generator output signal through serially connected power amplifier Vibrator5, the main vibration converter and the matching amplifier are connected to the signal input of the accompanying filter, the first output of which is connected to the first control input of the generator, the second output of the accompanying filter is connected to the first input of the phase detector, the output of which is connected through an serially connected absolute value detector and interpolator to the second control input of the generator, the first and second control outputs of the generator are connected to the control inputs, respectively, ca and accompanying filter, the output of each of the N additional vibratory transducers 0 five five 0 five 40 45 The distributors are connected to the input of the corresponding additional matching amplifier, so that, in order to increase the test performance, two N-input summing amplifiers, a differentiator, a source of reference voltage, N additional accompanying filters, N analog multipliers and N multichannel adjustable; Voltage dividers The output of the absolute magnitude detector is connected to the input of the interpolator, the outputs of the first and second summing amplifiers are connected respectively to the second input of the phase detector and the input of the differentiator, the output of which is connected to the counter input through the null detector, the outputs of which are connected to the control 1 GM inputs analog switch, the output of each additional matching amplifier is connected to the signal one in:;:: the corresponding additional accompanying filter, the signal output is connected to the first input of the corresponding analog multiplier, whose output is by;.; to the corresponding input of the paired totalizer of its amplifier, the output of the voltage source podklzschek to the inputs of multichannel divider controllers, the outputs of each of which are connected to a group of signal inputs corresponding analog switch; the output of which is connected to the second-iy code of the corresponding anz-talky multiplier, the second control output of the generator is connected to the control input; additional accompanying filters, the normal output of each additional accompanying filter is connected to the corresponding input of the second summing amplifier and the corresponding control recorder. V 5G UG / / g but  01 but W g / j | L CT / 2 W Ubrab / 1e And the next step is ynpaS / ienue step. lr rtfnnnii. ; "L ... rtn mrftp  je second ipopMbi fsf (}) on (time tre / 77bea forms Upr fsh f gjo but W JW / V Fig.z Compiled by V.Podol  DLSravchuk proofreader M.Vasilyeva Order 6278/44 Circulation 847Subscription VNIIPI State Committee of the USSR for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 U41222 ; CJ, 03 CJ ) but  and 6J ; (J d) e. ) Supervision on ve / rjffeafffi gjopMbf W (woo} 6 /