Impact Resistance of Plain and Twill Fabric in GFRP Measured by Active Thermography

Abstract

This paper discusses the impact resistance of glass-fibre reinforced polymer (GFRP) composites depending on the type of reinforcement -plain or twill weave. The values of impact energy were: 3J, 10J and 15J. Specimens featuring twill weave transferred higher force during the impact as compared with plain weave specimens. It was observed that an increase of impact energy was accompanied by an increase of the disproportion in transferred forces, in favour of twill weave specimens. Impact damage (in both types of weave) occurring as a result of 3J impact was undetectable with active thermography method. The damage area measured by means of active thermography for impact energy values equal to 10J and 15J proved that the type of reinforcement significantly influences the impact resistance of a composite.This has been justified by smaller damage areas with high spot intensity of damage in plain weave specimens and highly dispersed damage with lower intensity in twill weave specimens.

Mechanical characterisation of kenaf/PALF reinforced composite-metal laminates: Effects of hybridisation and weaving architectures

“…Similar findings were found in the research study conducted by Strugala et al. 43 in which twill woven-ply composites were able to absorb more energy compared to plain woven-ply composites. This could be attributed to the better energy dissipating characteristic in twill woven-ply.…”

Enhanced thermographic inspection of woven fabric composites by k-space filtering

“…Examples of such structured thermal background are displayed in Figure 1 for various defected woven fabric composites. These background disturbances have been frequently observed in literature [9,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. In [9,[19][20][21]34], woven composites are inspected using flash thermography, and the various weave patterns are clearly observable in the (post-processed) thermal images and limit the detection and evaluation of small and/or deep defect features.…”

“…Also here, the thermal background related to the weave pattern is found to be disturbing and deteriorates the evaluation of the thermal images. Furthermore, alternative thermographic methods, such as optical lock-in thermography [19], step heating thermography [35], eddy current thermography [30,31], current injection phase thermography [32], and heating through Peltier cells [29], for the inspection of woven composites have been reported. Each of these studies shows a strong structured thermal background, thus complicating the defect detection.…”