Comparison of Ultrasonic Methods for Detecting Defects in Unidirectional Composite Material

Abstract

Non-destructive tests are of pivotal importance in the industry, as they contribute to the decreasing of maintenance costs, reducing downtime and accidents. Ultrasound is a non-destructive method that can be used with several arrangements to identify faults in engineering materials. This work evaluated the use of three ultrasonic methods applied in FRP composites to detect manufacturing defects. The critically refracted longitudinal wave (LCR), the B-Scan images, and the signal-to-noise ratio of TFM (Total Focusing Method) images were compared to detect the delamination and the fiber waviness in unidirectional composite of carbon/epoxy. Rectangular samples without defects and with defects were used in the tests. To obtain the delamination in the samples, pieces of Teflon were placed between layers and for the samples with waviness, a silica sphere was used. The results showed that LCR wave is not recommended to detect these kinds of defects, the B-Scan image is efficient in detecting delamination, and the SNR variation of TFM images allows to identify the waviness and delamination in unidirectional FRP composites.

Damage detection in hybrid metal-composite plates using ultrasonic guided waves based on outliers estimate

“…Unlike metals, damage in composites appears prematurely, but propagates in a more stable way. Thus, they have an upper end compared to metals particularly when subjected to fatigue loading primarily because of the complicated relationship between the fibers, matrix, damage, and the residual stresses that block the propagation of damage [1]. In the case of fiber re-enforced composites, defects can occur in the matrix, fiber, or at the interface.…”

The Wrinkles Characterization in GFRP Composites by Infrared Active Thermography

“…The wrinkle detection in CFRP structures by the total focusing method (TFM) has been investigated by Ma et al [ 22 ]. A comparative study on the effectiveness of the ultrasonic damage detection method in delamination and fiber waviness detection has been presented by Vieira Goncalves et al [ 23 ]. In line with the current state of the art in the nondestructive inspection of aerospace composite laminates, infrared thermography (IRT), and thermal image processing techniques have been developed [ 24 , 25 , 26 , 27 ].…”