A new method for identifying elastic parameters of isotropic materials based on square specimens

Abstract

In order to solve the problem of errors caused by unstandardized operation of the impulse excitation technique in system identification, this paper proposed a method of measurement using a specimen plate with a square cross-section. The method was based on modern control theory to decouple the free vibration of a square specimen. First, the functional relationship between the intrinsic frequency of the specimen and the geometrical dimensions and mechanical parameters was established by combining the finite element method. Then, the continuous functional relationship derived by the homotopy method allowed the frequency ratio to be related to the thickness-to-length ratio and Poisson's ratio. By measuring the frequency ratio and thickness to length ratio, Poisson's ratio could be calculated using this functional relationship. When the density and Poisson's ratio were known, the Young's modulus could be performed inversely in conjunction with the finite element analysis. Finally, a comparison test between this method and the traditional impulse excitation technique was designed and implemented, and the results showed that this method has advantages in both testing efficiency and accuracy. The study provides a new idea for system identification, which has important application value and promotion significance.