Abstract: A system for testing articles with random and harmonic vibrations comprises a multichannel random signal shaper, a tuneable rejection filter connected to the output of the shaper, a vibrator connected to the output of the filter through an adder and a power amplifier which are placed in series, first and second tuneable filters and a signal spectrum analyzer connected to the first tuneable filter. The system according to the invention includes a variable-frequency harmonic signal generator, the signal spectrum analyzer representing a harmonic signal analyzer and comprising a harmonic signal control loop and a random signal control loop coupled thereto.

Abstract: A method of forming a desired vibration spectrum comprising the steps of preliminarily causing vibration of an article in a predetermined frequency range by the use of harmonic variable-frequency oscillations and using a multichannel signal shaper to produce specific values of spectral vibration acceleration density at each chosen check point on the article under test in each band of the predetermined frequency range, a random output signal level K in each channel being computed by solving a set of linear equations. A device for accomplishing the proposed method comprises the multichannel shaper connected to a vibrator mounting the article under test; vibration pick-ups secured at the chosen check points and connected through a switch to the input of a signal analyzer; a unit for setting parameters of a desired random vibration spectrum; and a control unit. The device forming the subject of the invention also comprises a variable-frequency harmonic oscillator and a memory unit connected thereto.

Abstract: A random vibrations testing device comprising a noise generator the output whereof is connected to an input of a wide-band filter. An output of the wide-band filter is connected directly and through paralleled narrow-band in-phase signal shaping channels to a means for shaping dips and spikes in the spectrum of a signal being shaped, which is electrically coupled with narrow-band opposite-phase signal shaping channels. The means for shaping the spikes and dips in the shaped signal spectrum is devised in the form of an adder series-connected to the wide-band filter, used commonly by all the narrow-band in-phase signal shaping channels and serving to form spikes in the shaped signal spectrum, and adders also series-connected to said wide-band filter, used individually by each opposite-phase narrow-band signal shaping channel and serving to form dips in the shaped signal spectrum.