Modal content-based damage indicators for disbonds in adhesively bonded composite structures

Abstract

Adhesive bonding is a promising joining method for composite materials. This article focuses on the use of modal content-based damage indicators to improve the sensitivity of guided waves to disbonds in the adhesive. Wave-defect interaction is modeled using frequency-domain finite element analysis in order to identify modes sensitive to adhesive degradation in joints between carbon fiber-reinforced polymer laminates. Phased array transducers and multielement array sensors designed for structural health monitoring are employed to enable preferential mode excitation and modal content extraction, respectively. The domains in dispersion curve space predicted to have good, intermediate, and no sensitivity to disbond were experimentally found to have good, intermediate, and limited sensitivity using a feature of the received signals associated with the modal amplitude or a modal amplitude ratio. Furthermore, the modal amplitude was found to decrease monotonically with increasing disbond size, demonstrating that it has potential to quantitatively size disbonds.

In-line inspection of unpiggable buried live gas pipes using circumferential EMAT guided waves

“…The objective to use frequency domain analysis is to study the transmission coefficient change due to the wave-defect interaction for different defect sizes. Figure 7 shows the sketch of the FEA model used in the frequency domain analysis 16 . A stripe of the plate structure is created to simulate plane wave propagation by applying periodic boundary condition to the surfaces parallel to both wave propagation and thickness direction.…”

A Guided Wave Sensor Enabling Simultaneous Wavenumber-Frequency Analysis for Both Lamb and Shear-Horizontal Waves

“…The lateral surfaces of the strip have traction free boundary conditions applied to the top and bottom and periodic boundary conditions on the left and right. The advantage of using a strip model is that it enables plane wave propagation of both Lamb and SH waves and it is computationally efficient [24]. Guided wave actuation is through application of displacement boundary conditions to a cross section of the aluminum plate.…”

“…Its array configuration guarantees that wavenumber-frequency analysis by signal post-processing enables different modes at the same frequency to be resolved and separated. Such a low-profile, low-mass, conformable, inexpensive sensor is ideal for SHM and other applications [23,24]. Wave actuation could come from any source, although for SHM many of the same features are desirable.…”

A fully coupled model for actuation of higher order modes of Lamb waves

“…Periodic boundary conditions are assumed on surfaces parallel to the XZ-plane. It should be noted that this model is a 3D slice model that can model both Lamb and shear horizontal type waves [16,17]. Usually, a 2D plane strain model is sufficient to simulate Lamb wave excitation with PZT elements.…”