METHOD FOR DETERMINING PARTIAL FREQUENCIES OF A CONTROLLED SURFACE OF AN AIRCRAFT AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2020 - IPC G01N3/00 G01N29/00 

FIELD: aircraft; rocket engineering.

SUBSTANCE: invention relates to the field of aviation or rocket equipment, namely to measurement of frequency characteristics (partial frequencies) of the controlled surface (CS) of aircraft (AC) required for flutter analysis. Disclosed is method, in which is fixed in space aircraft or its compartment with controlled surface and its drives, vibro sensors and electric exciters of electrodynamic type are attached to controlled surface, points of application of forces of which are located on different sides from axis of rotation CS at equal distance from axis of rotation CS and at equal distance from termination of axis of rotation CS on body AC projection of points of application of forces on this axis, remaining elements of device are assembled, described below in the description of the device of the invention, electric power is supplied, including to the CS drive to ensure its operating state. Modal CS tests are carried out using the phase resonance method and determining natural frequencies of CS rotation and bending tones, preset defined natural rotation frequency as initial, initial values of real components of forces from two force exciters, in complex representation of forces or forces of sinusoidal type, equal in value and opposite in sign (this condition will be satisfied in future) and performing several tests, changing values of real components of forces and introducing imaginary component of force (forces), that is, force (forces) of cosine type (there are possibilities of changing ratio and level of imaginary components of forces, both step-by-step and continuously). Note here that the nodal line position, the phase resonance condition and the first and second partial tone indication signals (these signals are determined based on readings of sensors in real time in unit for indicating partial tones; first indication signal is equal to the real part of the angular amplitude of the undetectable tone divided by the modulus of the angular amplitude of the determined tone, the second indication signal is equal to the modulus of the angular amplitude of the undetectable tone divided by the modulus of the angular amplitude of the determined tone) until four conditions have been simultaneously observed. In order to determine partial bending frequency CS, preset defined bending frequency as initial, initial values of real components of forces are set, equal by value and by sign (this condition will be satisfied in future) and performing a series of tests similar to tests described above; further actions coincide with actions described above. Device comprises vibrating sensors attached to controlled surface AC, electrodynamic type load rams (LR) attached to controlled surface AC, signal amplifiers from sensors, commutators, a harmonic signal generator (HSG) with force selection units (FSU), a data collection system (DCS), a partial tone indication unit (PTIU).

EFFECT: shorter time and higher accuracy when determining partial frequencies of the controlled surface.

7 cl, 3 dwg