APPLICATION OF THE RESONANCE METHOD AND THE SPECKLE INTERFEROMETRY METHOD FOR MEASURING THE DYNAMIC CHARACTERISTICS OF CONSTRUCTIONS

Experimental testing of rocket and space techniques is one of the most difficult, time-consuming and expensive stages of the development and creation of these products. Modern development methods tend to reduce the proportion of experimental studies and replace them with numerical modeling. However, the correspondence of the numerical model to the real object is determined by the initial data, so it is not possible to completely abandon the full-scale testing of products. Particular attention in the development and creation of rocket and space techniques is paid to vibration effects. Obtaining reliable basic dynamic characteristics of the product during vibration tests in a purely theoretical way is practically impossible. So the damping coefficients can only be determined experimentally. The paper analyzes the main methods for determining dynamic characteristics, and a choice is made in favor of the resonance method. The accuracy of determining the dynamic characteristics by the resonance method depends on the accuracy of the construction of the resonance curve. In this paper, to construct a resonance curve, it is proposed to use a speckle interferometer, which allows simultaneously recording the shape of natural vibrations and amplitude, using time averaging methods and speckle interferometry on a single speckle. It is shown that speckle interferometry on a single speckle makes it possible to measure the amplitudes of natural vibrations in real time and with high accuracyт ̵  less than one-eighth of the wavelength of the laser radiation used in the speckle interferometer. These circumstances are especially important in the development and creation of spacecraft with precision equipment.