Detection and characterization of matrix cracking in fiber‐metal laminates using Lamb wave propagation

Abstract

The purpose of the present study was to assess the capability of finite element (FE) simulations of guided Lamb wave propagation for the characterization of the modulus of fiber-metal laminates (FMLs) and detection of the matrix cracking in them. An FE model of an FML specimen with a [Al/90 2 /Al/ 90 2 /Al] layup was developed. The matrix cracking with different densities was also induced in the fiber-reinforced composite layers of the FML model. The fundamental antisymmetric Lamb wave mode was propagated on the developed model at frequencies from 50 to 300 kHz. The Lamb wave velocity was obtained from the FE models at different frequencies. Then, the inverse Lamb wave propagation problem was solved and the elastic modulus of the simulated FML specimen was estimated. An experimental program was conducted to evaluate the results of FE simulations. The FML specimens with the same layup and materials were fabricated and underwent the tensile and Lamb wave propagation tests. The average elastic moduli of the specimens obtained from the tests, classical lamination theory, and FE simulations were in good agreement, especially at low frequencies. It was observed that the sensitivity of the Lamb wave velocity to matrix cracks was higher at high frequencies.