Characterization of multilayer delaminations in composites using wavenumber analysis: numerical and experimental studies

Abstract

Delamination is one of the most common and dangerous failure modes for composites because it takes place and grows in the absence of any visible surface damage. The successful implementation of delamination detection in aerospace composite structures is always challenging due to the general anisotropic behavior of composites and multilayer delamination scenarios. This article presents a numerical and experimental investigation to detect and characterize the multilayer delaminations in carbon fiber–reinforced polymer composite plates using guided waves and wavenumber analysis. Multiphysics three-dimensional finite element simulations of the composite plate with five different delamination scenarios are conducted to provide the out-of-plane wave motion for wavenumber analysis. The out-of-plane results from finite element simulations of one delamination and two delaminations are validated by the scanning laser Doppler vibrometer measurements. It is found that the wavenumber analysis can identify the plies between which the delamination occurs and evaluate the delamination severity by comparing the new wavenumbers due to the trapped waves in the delamination regions, which is potentially related to delamination severity. Both numerical and experimental results demonstrate a good capability for the detection and characterization of multilayer delaminations in composite structures.

Guided wave scattering at a delamination in a quasi-isotropic composite laminate: Experiment and simulation

“…The scattering directivity pattern has been shown to be influenced by the fibre orientation of the outer plies of the laminate, due to fibre steering effects [22]. Scattering patterns depend on the layup sequence, even for laminates with the same number of ply layers [34]. Mei et al found that the number of delaminations at the same location with different depths has an influence on the scattering pattern and the amplitude of trapped waves [35].…”

Statistics-based baseline-free approach for rapid inspection of delamination in composite structures using ultrasonic guided waves

“…21 However, defect identification using scattering studies typically requires understanding complex mode conversion phenomena, and basis conversion (wave-number/frequency) may be needed for estimating the strength of scattered signals. [22][23][24] On the other hand, wave visualization is a robust technique to identify the defects in any structure. Nevertheless, it consumes a large amount of data storage and acquisition time.…”

“…21 However, defect identification using scattering studies typically requires understanding complex mode conversion phenomena, and basis conversion (wave-number/frequency) may be needed for estimating the strength of scattered signals. 22–24…”

Influence of Composite Thickness on Ultrasonic Guided Wave Propagation for Damage Detection

“…However, this information is not known; therefore, it is important that during the design and development phase of any SHM system, a detailed investigation is carried out to choose the optimum parameters of the UGW (frequency, amplitude and mode), which will interact with probable damage types in the plate and enable a reliable damage detection. Many studies have been numerically carried out to capture the guided wave propagation properties in thin composite structures of different layups, materials, complexities and sizes numerically, since experimental investigations are often timely and expensive to allow a deeper understanding of the wave/damage interaction to optimise the parameters of the SHM system, towards condition-based maintenance concepts [ 5 , 11 , 18 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ].…”