Impact damage assessment in orthotropic CFRP laminates using nonlinear Lamb wave: Experimental and numerical investigations

Abstract

In this study, experimental and numerical approaches based on the nonlinear ultrasonic Lamb wave are used to detect the barely visible impact damages (BVID) in orthotropic CFRP laminates due to low velocity impact (LVI). A drop-weight impact test system and a RITEC nonlinear ultrasonic system are adopted for experimentally measuring the higher harmonics of lamb wave in the damaged CFRP laminates. An integrated finite element (FE) model is proposed to further identify the interaction between Lamb wave and impact damages, in which Hashin criterion and triangular cohesive zone model (TCZM) are used to predict the initiation and evolution of delamination and other damages under LVI. Then, the displacement–time signal and the relative acoustic nonlinear parameters (RANP) of the Lamb wave excited by sinusoidal displacement load are extracted to evaluate the damage in the same FE model. Finally, the relevance between LVI damage and RANP is investigated by numerical and experimental analyses under LVI with different energies, and shows that the amplitudes of harmonics and RANP increase with the raise of the impact energy, as well as the delamination areas. Therefore, the amplitude of harmonics and RANP can be used as indicators to detect BVID.