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.
Highlights
Among the materials that are used to make mechanical components, the composites are widely used in the aerospace industry, with aircraft having up to 80% of their structural volume made of them, such as the Boing 7871
The results for the ultrasonic methods under evaluation are presented
This work aimed to evaluate different ultrasonic methods for defect detection in unidirectional carbon/epoxy composite. Defects such as delamination and fiber waviness were investigated using LCR waves through the time-of-flight (TOF), phased array system through B-Scan image, and the signal-to-noise ratio (SNR) variation obtained from the Total Focusing Method (TFM) image
Summary
Among the materials that are used to make mechanical components, the composites are widely used in the aerospace industry, with aircraft having up to 80% of their structural volume made of them, such as the Boing 7871. High speed trains, wind energy equipment, oil and gas, defense, naval, automotive, and construction industries widely employ these materials[2,3,4]. Their advantages are tailorable properties, high strength, low density, corrosion resistance, and fatigue strength[5,6]. The damages appear prematurely[7], but they usually propagate in a stable way This apparent contradiction makes them advantageous when compared to metals, for parts under variable loads, subject to fatigue. The damage is imperceptible in visual inspections[9,10] This is even more critical with structures and covers in equipment where life risks are involved
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