FI77935C - Apparatus for testing articles with respect to random vibration. - Google Patents

Description

τ r i 77935

Device for investigating random vibrations in products

The present invention relates to mechanical testers and more particularly to vibration testers and in particular to random vibration testers.

The random oscillation tester according to the invention can be used to study the effect of random oscillation on various products for generating and analyzing random oscillations having a predetermined spectrum and for correcting the amplitude-frequency response of the oscillator.

A random oscillation tester is known in the art, comprising a noise generator whose output is connected to the inputs of channels connected in parallel with a signal having a predetermined spectrum. Each channel comprises a narrowband filter, the output of which is connected to the input of an adjustable amplifier, the output of the amplifier being in turn connected to the second input of the adder. The output of the adder is connected to the input of the vibrator, the output of the vibrator being connected to the input of the vibration detector. The output of said detector is connected to the inputs of channels connected in parallel for analyzing the spectrum of the random signal 25. Each channel comprises a narrowband filter, the output of which is connected to the input of the dispersion meter, the output of the meter being in turn connected to the other input of the comparator unit. The second input of the comparator unit is connected to a program voltage setter, while the output of the comparator unit is connected to the adjustable amplifier control input of the channel generating the signal in question.

In the above-mentioned tester, the amplitude-frequency-35 response of the oscillator loaded with the product to be tested is corrected for adjusting the gain of the adjustable amplifiers in the signal-generating channels, adversely affecting the dynamic range of set variations in the simulated oscillation spectrum.

Another random vibration tester used in electrodynamic vibrators and comprising a noise generator having an output connected to the input of a broadband filter is also known in the art. The output of said filter is in turn connected to the inputs of narrowband filter-10 amplifiers connected in parallel and to the second input of the adder, while the outputs of the narrowband filter-amplifiers are connected to the inputs of the phase inverters, the outputs of the phase inverters being connected to the second input of the adder.

15 The use of a broadband filter, phase inverters, high-bandwidth filter amplifiers, and an adder expands the range of set variations in the simulated oscillation spectrum. However, also in this tester, the amplitude-frequency response correction of the oscillator is performed by adjusting the gain of the narrowband filter amplifiers, which of course prevents the realization of a wide dynamic range of the set variations of the simulated oscillation spectrum.

Another random oscillation tester 25 has been proposed, comprising a noise generator whose output is electrically connected to the channels connected in parallel to generate a signal having a predetermined spectrum. Each channel comprises a narrowband filter amplifier, the output of which is connected to the input of a dispersion meter, the output of said meter being in turn connected to the other input of the comparator unit. The second internal input of said unit is connected to the program voltage setter, while the output of the comparator unit is connected to the control input of the ka-35 high bandpass filter amplifier.

3,77935

The output of the filter amplifier is also connected to an adder, the output of which is electrically connected to the input of the oscillator, which has means for correcting the amplitude-frequency response of the oscillator.

In the above-mentioned tester, the means for correcting the amplitude-frequency response of the oscillator comprises an oscillation detector, the input of which is connected to the output of the oscillator and the output is connected to the input of the correction amplifier, the output of said amplifier being in turn connected to the input of the power amplifier. However, such a tester cannot correct the amplitude-frequency response of the oscillator over a wide dynamic range due to the limitations imposed by the gain of the correction amplifier.

It is an object of the present invention to provide a random oscillation tester in which the means for correcting the amplitude-frequency response of the oscillator is made to give a wide dynamic range of set variations in the spectrum of simulated oscillations and does not affect the stability of the tester.

The above object is achieved by a random oscillation tester comprising a noise generator whose output is electrically connected to parallel-connected channels to form a signal having a predetermined spectrum, each channel comprising a narrowband filter amplifier whose output is connected to a dispersion meter. the output of the dispersion meter being in turn connected to the second input of the comparator unit 30 with its second input connected to the program voltage setter and the output connected to the control input of the narrowband filter amplifier, the output of the filter amplifier being connected to an adder 35 wherein the oscillator has means for correcting its amplitude-frequency response, said means for correcting the amplitude-frequency response of the oscillator comprises a load element and two circulators, the second circulator the first terminal is connected to the output of the noise generator, the second terminal of said circulator is connected via a load element to the input of the oscillator and the third terminal is connected to the zero potential rail, while the first terminal of the second circulator is connected directly to the second chip to the input, the second terminal of the second circulator is connected to the input of a narrowband filter amplifier, which filter amplifier is common to both channels of the signal having a predetermined spectrum, and the third terminal of the same circulator is connected to the output of the adder.

With such an embodiment of the random oscillation tester according to the invention, the dynamic range of the set variations in the spectrum of the simulated oscillations can be increased and the operation of the probe can be made more stable.

The invention will now be described in more detail by means of a specific embodiment, shown by way of illustration with reference to the accompanying drawings, in which Figure 1 is a block diagram of a random oscillation tester according to the invention, Figure 2 is a functional diagram of the tester of Figure 1, and Figures 3a, b, c, d. The spectrum of the signal of the output of the tester of the tester of Fig. 1, the amplitude-frequency response of the vibrator of the tester of Fig. 1, the spectrum of the signal present at the input of the vibrator of the tester of Fig. 1 and the spectrum of vibration affecting the stage of the tester vibrator of Fig. 1, respectively.

5,77935

The random oscillation tester according to the invention comprises a noise generator 1 (Fig. 1) adapted to generate a random signal with a wide frequency band, the current density spectrum of which is uniform in the working frequency range. The output of the noise generator 1 is electrically connected to the inputs of the channels 2 connected in parallel to form a signal having a predetermined spectrum. Each channel 2 comprises a narrowband filter amplifier 3, the output of which is connected to the input of a dispersion meter 4, the output of which is in turn connected to one input of the comparator unit 5, the other input of the comparator unit 5 being connected to the output of the program voltage adjuster 6. The outputs-15 of the comparator unit 5 are connected to the control inputs of the narrowband filter amplifiers 5, while the outputs of the narrowband filter amplifiers 3 of the channels 2 generating the signal having a predetermined spectrum are connected to the inputs of the adder 7. .

The tester according to the invention also comprises an oscillator 9. The input of the oscillator 9 is electrically connected to the output of the noise generator 1 and to the output of the power amplifier 25 8 by means 10 for correcting the amplitude frequency response of the oscillator 9.

The amplitude-frequency response correcting means 10 of the oscillator 9 comprises a load element 11, which is in fact a pure electrical resistor, and two well-known circulators 12, 13, which are in fact multi-port networks.

The first connector of the circulator 12 is connected. . ie to the output of the noise generator 1, the third terminal is connected via the load element 11 to the input of the oscillator 35 9 and the third terminal is connected to the zero potential bus. The first terminal 6 77935 of the circulator 13 is connected directly to the input of the oscillator 9 and via the load element 11 to the second terminal of the circulator 12. The second terminal of the circulator 13 is connected to the inputs of the narrowband filter amplifiers 3 of the signal generating channels 2, and the third terminal is connected to the output of the power amplifier 8.

The operation diagram of the random oscillation tester shown in Fig. 1 is shown in Fig. 2.

The noise generator 1 (Fig. 2) comprises a voltage stabilizer diode 14 operating in the manner of an "avalanche breakdown" controlled by a resistor 15 placed between the cathode of the voltage stabilizer diode 14 and the collector of the transistor 17, which together form a resistor 17. The frequency of the generated noise spectrum Lower 15 is determined by the capacitor 18. The power is supplied to the amplifier along the rail 19. The collector of transistor 16 is connected to the first terminal of circulator 12.

The second connector of the circulator 13 is connected to the inputs 20 of the signal generating channels 2, namely to the supply resistors 20 of the narrowband filter amplifiers 3. Each filter amplifier 3 is built around an operational amplifier 21. Resistors 20, 22 and capacitors 23, 24 form the resonant center frequency of the narrowband filter amplifier 3. The output of the operational amplifier 21 is connected to a series-connected resistor 25 and a photoresistor 26. The photoresistor 26 and the light emitting diode 27 form an optically coupled pair (optocoupler) 28 and a core structurally housed in a common housing 30.

The photoresistor 26 of each filter amplifier 3 is connected to the input of the corresponding dispersion meter 4, i.e. to its input diode 29. The dispersion meter 4 is based on an operating amplifier 30. The integration time constant 35 depends on a resistor 31 and a capacitor 32 set in the feedback field of the operating amplifier 30.

Each output of the operational amplifier 30 of the dispersion meter 4 is connected to a resistor 33, which is in fact one input of the comparator unit 5 built around the operational amplifier 34, while the resistor 35 acts as the second input of the comparator unit 5. The degree of comparison accuracy of the comparator unit 5 depends on the gain of the operational amplifier 34, which in turn is determined by the resistor 36. The sliding contact of the potentiometer 37 of the program voltage adjuster 6 is connected to the resistor 35. The reference voltage source 38 is connected to the potentiometer 37. The output of the operational amplifier 34 is connected .

The adder is based on an operational amplifier 39, the feedback circuit of which includes a resistor 40. The resistors 41, 42 are in fact the input resistors of the adder 7 and are connected to the outputs of narrowband filter amplifiers 3, namely resistors 25. The output of the operational amplifier 39 is connected to the power amplifier 8.

In order to make it easier to understand the operating principle of the random oscillation tester according to the invention, Figures 3a, b, c, d are shown, in which the frequency OJ is plotted as an abscissa, the spectra G (£ J) are plotted as ordinates in Figures 3a, c, d and the amplifier 9 amplitude. the frequency response K (0)) is plotted as an ordinate in Fig. 3b.

Figures 3a, b, c, d show the signal spectrum 43 at the output of the noise generator 1, the amplitude-frequency response 44 of the oscillator 9, the signal spectrum 45 at the input of the oscillator 9 and the oscillation spectrum 46 of the oscillator 9 on stage 47 (Figure 1), respectively.

The random vibration tester according to the invention operates as follows. A wide frequency band 8,77935 signal with a power density spectrum 43 (Fig. 3a) uniform in the operating frequency range is fed from the output of the noise generator 1, i.e. the collector of the transistor 16, to the first terminal 5 of the circulator 12, from where the undistorted signal enters the second chip is fed to the load element 11, i.e. to the pure electric resistor and further to the input of the oscillator 9 having the amplitude-frequency response 44 (Fig. 3b) and to the first terminal of the circulator 13 (Fig. 2). The signal has a spectrum 45 (Fig. 3c) which is inversely proportional to the amplitude-frequency response 44 of the oscillator 9.

The above signal then passes from the first terminal of the circulator 13 (Fig. 2) to its second terminal 15 and further to the supply resistors 20 of the signal generating channels 2. The narrowband filter amplifier 3 of each signal generating channel 2 separates its input signal (resistor 20) from the entire spectrum 45 only those spectral components 20 that fall within its frequency bandwidth. The average gain frequency of the filter amplifier 3 is determined by the resistors 20, 22 and the capacitors 23, 24, while its frequency passband also depends on the gain of the operational amplifier 21.

The narrowband signal is then fed from the output of the operational amplifier 21 to the resistor 25 and further to the photoresistor 26. The strength of the narrowband signal arriving from the photoresistor to the input of the dispersion meter 4, i.e. diode 29, is determined by the ratio of resistor 25 to photoresistor 26. The signal in question is thus the output signal of the narrowband filter amplifier 3.

Next, the signal is applied from the output of the operational amplifier 35, which is in fact the output of the dispersion meter 4, to one input of the comparator unit 5, namely the resistor, at a fixed voltage equal to the dispersion of the narrowband signal at the output of the filter amplifier 3. . The second input of the comparator unit 5 based on the operational amplifier 34 is a resistor 35 to which a voltage is applied from the sliding contact of the potentiometer 37 of the program voltage adjuster 6. The reference voltage source 38 supplies a reference voltage.

Subsequently, an error signal proportional to the difference between the voltage of the programmer 6 and the voltage of the signal from the output of the dispersometer 4 is applied to the light emitting diode 27. As a result, the incandescence intensity of the light emitting diode 27 increases or decreases depending on the input error signal. This in turn 15 decreases or increases the resistance value of the photoresistor 26 and thus changes the strength of the narrowband signal at the output of the narrowband filter amplifier 3.

The signal then arrives from the output of the narrowband filter amplifier 3 to one of the 20 inputs of the adder 7 (i.e. to the resistor 41 or 42). The integrated signal is fed from the output of the adder 7 to the input of the power amplifier, whereby the amplified signal is fed from the output of the power amplifier to the third terminal of the circulator 13. When the sliding contacts of the potentiometers 37 of the voltage generators 2 of the signal generating channels 25 are moved to a position corresponding to a single gain of the filter amplifiers 3, the signal at the output of the power amplifier 8 has a spectrum 45 (Fig. 3c) the spectrum of the input signal (Figure 2). From the third terminal of the circulator 13, a signal arrives at the first terminal of the circulator 13 and further at the input of the oscillator 9. As soon as the oscillator 9 is aroused by a signal whose spectrum is inversely ver-35 swinging to square 10 77935 of its amplitude frequency response 44 (Fig. 3b), the platform 47 of the vibrator 9 begins to simulate signals (Fig. 2) having a common spectrum 46 (Fig. 3d).

The vibration tester 5 according to the invention can increase the dynamic range of the set variations of the simulated vibration spectrum as a result of the predistortion of the noise generator spectrum according to the square of the amplitude-frequency response of the vibrator and provide a good operating stability of the tester.

In addition, the use of the tester according to the invention provides greater reliability in experiments investigating the effect of random vibration, whereby these experiments are cheaper.

In describing a particular embodiment of the invention, certain narrow terminology has been used for clarity. It is to be understood, however, that the invention is in no way limited to these selected terms, but that these terms encompass all equivalent elements that function in the same manner to achieve the same purposes.

Although the invention has been described herein with reference to a preferred embodiment, it will be apparent that minor changes and modifications may be made without departing from the spirit and scope of the invention, as will be well understood by those skilled in the art.

Such changes and modifications are to be considered within the scope of the invention as defined by the appended claims.

Claims (1)

Claim oscillation tester comprising a noise generator (1), the output of which is electrically connected to parallel-connected channels (2) adapted to generate a signal having a predetermined spectrum, each channel comprising a narrowband filter amplifier (3) , the output of which is connected to the input of the dispersion meter (4), the output of the dispersion meter 10 being in turn connected to the second input of the comparator unit (5) with its second input connected to the program voltage setter (6) and the output connected to the narrowband filter amplifier (3) , wherein the output of the filter amplifier 15 is also connected to an adder (7), the output of which is electrically connected to the input of the oscillator (9), the oscillator having means (10) for correcting its amplitude-frequency response, characterized in that the means (10) ) to correct the amp-20 litudi-frequency response of the oscillator (9) comprises a load gesture (11) and two circulators (12, 13), the first connector of the circulator (12) being connected to the output of the noise generator (1), the second connector being connected to the input of the oscillator 25 (9) via the load element (11) and the third connector being connected while the first terminal of the circulator (1) is connected via a load element (11) to the second terminal of the circulator (1) and directly to the input of the oscillator (9), the second terminal is connected to the input of 30 narrowband filter amplifiers (3). common to both channels (2) forming a signal having a predetermined spectrum, and a third terminal is connected to the output of adder 7. 12 77935 Anordning for the supply of a signal to a high voltage vibration generator, a single in-5 voltage and a brass signal generator (1), a shield from an electrical risk to a parallel cable channel (2) for the formation of a signal from a high frequency spectrum, och en, innefattar en smalbandig filterförstärkare (3), vars utgäng är kopplad till en ingäng hos en sk 10 dispersions (4), shafts are fitted to the end with a single handle (5), shafts and shafts are fitted with a program set (6) and a shafts are fitted to the styrofoam with a filter holder (3) the cut-off is provided with the vibrator (7), the cut-off is provided with the vibrator (9), which is applied to the vibrating body (10) for the correction of the vibrator (9) araplitud-frequency frequency, the spark plugs, the corrugated organ 20 (10) for adjusting the vibrator (9) amplitude-frequency curve to the input element (11) and to the circulator (12, 13), colors for the circulating channel (12) for the connection to the brass signal generator (1) och dess andra anslut-25 ningsklämma genom belastningselementet (11) is used as a vibrator (9) ingäng, Medan den firsta cirku-latorns (12) tredje anslutningsklämma är asluten till en nollpotentialskena, varvid d and other circulators (13) are connected to the genome of the circulating elements 30 (11) are connected to the circulators (12) and are connected to the vibrators (9) are used, the average of the circulators (13) is used smalbandiga filterförstärkaren (3) i alla de channelerna (2) 35 för formning av en signal with the best frequency spectrum and on the other hand, the connection block is connected to the adderarens (7).