A review of works devoted to the determination of the mechanical properties of the composites. A plant and an experiment to study the dynamic properties of polymer composites sample cut from the spar manufactured winding way, the blades of a helicopter rotor. Developed finite element model used in the experiment samples and numerical analysis and identification of vibration modes on the basis of which the developed methods of refinement of the elastic moduli of polymer composites, obtained experimentally using a static test.