METHOD FOR FATIGUE TESTING OF PROPELLER BLADES AND INSTALLATION FOR ITS IMPLEMENTATION Russian patent published in 2022 - IPC G01M5/00 G01M7/06 G01N3/32 G01N3/34 

FIELD: testing equipment.

SUBSTANCE: invention relates to the field of testing equipment, in particular to equipment for strength testing of full-scale blades of helicopter and aircraft propellers. The method consists in the fact that two blades are joined by end sections using a flexible connection (hereinafter referred to as the sample). The flexible connection is attached to the reinforced end parts of the blades. The flexible connection is made in the form of a plate made of a composite material, which has a low bending stiffness. The sample is mounted on the frame with the butt parts on one side with a pivotally fixed node, and on the other with a pivotally movable node in the longitudinal direction. A strain bridge is glued to the blade, which is calibrated by applying a bending static load. The sample is loaded with an axial tensile force with a force exciter. An eccentric inertial vibrator excites the bending vibrations of the sample on the ascending branch of the resonance. In the process of vibration loading, the amplitude of deflections of the sample is measured using a displacement sensor and the amplitude of the bending moment according to the signals of the load cell. The dependence of the amplitude of the deflection on the amplitude of the bending moment is determined. According to this dependence, the amplitude of the deflection is determined, which is reproduced to obtain a given amplitude of the bending moment. Fatigue tests of the blades are carried out with the maintenance of a given value of the axial force and a given amplitude of the bending moment. The installation contains the following: a sample consisting of two blades joined together by a flexible connection, a hinge-fixed unit, with which the sample is attached to the frame on one side by the butt end, a hinge-movable unit, with which the sample on the other side by the butt end is attached to a movable support, with the possibility of free movement of the hinge assembly in the longitudinal direction. An exciter for loading the sample with a tensile force installed in series with the sample using a swinging lever, dynamometer, cables and a damper. An eccentric inertial vibrator suspended from the end parts of the blades with the possibility of their free vertical movement. The eccentric inertial vibrator is connected to the hydraulic motor by means of a driveshaft. With the help of a power exciter, a given tension force of the cable is maintained and, accordingly, loading by the longitudinal force of the blades. With the help of a hydraulic motor, the rotation speed of an eccentric inertial vibrator is maintained, at which a given value of the amplitude of the oscillation of the blades is reached.

EFFECT: increasing the reliability of testing by approximating the loading conditions and fixing the blade in bench conditions to the conditions of its operation on the aircraft.

3 cl, 3 dwg