Identification of the Elasticity and Damping Characteristics of a Fiberglass Based on a Study of Dying Flexural Vibrations of Test Samples

A procedure for identification of the elastic characteristics and amplitude dependences of the logarithmic vibration decrement of a fiberglass, upon its deformation along the warp and weft directions and in shear, from given elastic and damping characteristics of multilayer test samples is put forward. To identify the elastic characteristics of the fiberglass, a dynamic method based on comparison of experimental and calculated free frequencies of a test sample is used. The sought-for amplitude dependences are approximated by polynomials. For determination of their coefficients, it is proposed to use direct methods with minimization of a target function constructed by comparing the experimental and calculated logarithmic vibration decrements of the test sample. In order to accelerate the process of search, an algorithm of express run is used to find the amplitudes and logarithmic vibration decrements of the test sample for solving the direct problem. Examples of identification of the elastic and damping characteristics of the fiberglass by using data of physical experiments on different series of test samples are presented.