Uncovering the fatigue damage initiation and progression in uni-directional non-crimp fabric reinforced polyester composite

Ex-situ X-ray computed tomography, tension clamp and in-situ transilluminated white light imaging data of non-crimp fabric based fibre composite under fatigue loading

“…The specimen geometry used was a modified version of the butterfly geometry optimised for testing unidirectional fibre composites [2] , however with a smaller cross-section (10 × 2 mm 2 ) to get higher image resolution in the X-ray CT experiments [1] . The material considered was a non-crimp glass fibre fabric based fibre composite where most of the fibres are oriented in the loading direction as unidirectional (UD) bundles.…”

“…The lay-up of the non-crimp fabric based fibre composite considered was [0/b,0/b] where ‘0’ refers to the axial fibre bundles and ‘b’ the backing fibre bundles. In the gauge section the outer backing layer was removed resulting in the layup [0/b,0], which was done to study the effect of one layer of backing in between two layers of UD fibre bundles (see also [1] for additional information).…”

“…The strain was monitored by two extensometers mounted on the sides of the specimens to not be in the way of the camera used for the TWLI. The 12 fatigue tests were all interrupted before failure (see details in Table 2 in [1] ) and the one specimen used for the ex-situ X-ray CT fatigue test was interrupted for examination after 100,000, 150,000, 200,000, and 500,000 cycles.…”

“…Transilluminated white light imaging was carried out by lighting the specimen up from the back using an LED lamp and capturing images of the lit-up specimen using a high-resolution camera. For each specimen pen markers with 20 mm length in between were placed to be used for automatic crack counting algorithm (see [ 1 ]). Photos were captured during the fatigue test without interruptions (in-situ) and to decrease the data load photos were only captured 100 times during each cycle decade meaning that more photos are captured in the beginning of the test than after a higher number of cycles.…”

Effect of fatigue loading on stiffness degradation, energy dissipation, and matrix cracking damage of CFRP [±45]3Scomposite laminate

“…Various crack detection techniques recently used in polymer matrix composites are stereoscopic travelling microscope equipped with digital camera, trans-illuminated white light imagining (TWLI), high-resolution CCD camera, modified ultrasonic C-scan using shear waves, through-transmission ultrasonic C-scan, lamb waves technique, noncontact fibre optic displacement sensors, surface mountable crack detection sensor (SMCS), and so on. [74][75][76] Similarly, Micro-Electro-Mechanical Systems (MEMS) incorporated with gyroscopes, accelerometers and magnetometers, and miniature X-Gator sensors have multi-parameter monitoring capability like load, displacement, impact, and so on. The efficient and problem defined use of these techniques in fatigue prone structures will permit non-destructive residual life estimation.…”