Parametric studies of composite material properties influence on dispersion curves of Lamb waves

摘要

Typically, material properties originate from destructive tensile tests and are used in computational models in the design and analysis process of structures. This approach is well-established in relation to isotropic homogeneous materials. However, if this approach is used for composite laminates, inaccuracies can arise that lead to vastly different stress distributions, strain rates, natural frequencies, and velocities of propagating elastic waves. In order to account for this problem, the alternative method is proposed, which utilizes Lamb wave propagation phenomenon and optimization techniques. Propagating Lamb waves are highly sensitive to changes in material parameters and are often used for structural health monitoring. In the proposed approach, the elastic constants, which arc utilized to determine dispersion curves of Lamb waves, are optimized to achieve a good correlation between model predictions and experimental observations. In the first step of this concept, parametric studies have been carried out in which the influence of mass density, Young's modulus. Poisson's ratio of reinforcing fibers as well as a matrix of composite laminate and volume fraction of reinforcing fibers on dispersion curves of Lamb waves was investigated. The dispersion curves of Lamb waves were calculated by using the semi-analytical spectral element method considering the variability of properties of composite constituents. The resulting dispersion curves were also compared with experimental measurements of full wavefield data conducted by scanning laser Doppler vibrometer and processed by 3D Fourier transform. It allowed formulating fitness function which will be next used in a genetic algorithm for optimization and identification of elastic constants.