Investigation of indentation damage resistance on normal and inclined plane of glass/epoxy composite laminates using acoustic emission monitoring

Abstract

This work relates to the investigation of indentation induced damage resistance in glass fiber reinforced polymer composite laminates under normal and inclined planes. Uni-directional [0] and cross-ply [0/90] glass fiber reinforced polymer composite specimens were subjected to 0° and 20° indentation loading with acoustic emission monitoring. The specimens were loaded at the centre using a hemispherical steel indenter with 12.7 mm diameter. Mechanical responses such as force–displacement behavior, absorbed energy and resulting damage area were used for the quantification of the indentation damage. Acoustic responses such as normalized cumulative counts, energy, duration and peak frequency were considered for monitoring damage progression during 0° and 20° indentation loading. The residual compressive strength of the glass fiber reinforced polymer specimens following indentation was measured by testing them under in-plane loading, once again with acoustic emission monitoring. The correlation between mechanical and acoustic strain energy was used for the evaluation of the damage severity of the laminates. The result revealed indentation damage resistance in cross-ply laminates as 65.08% and 68.01% higher than uni-directional laminates for 0°, whereas for 20°, there was a reduction in the damage resistance in cross-ply laminates to 43.27% and 57.39%. These were higher than uni-directional laminates under the displacements of 2 mm and 3 mm, respectively. The conclusion from these results was that transverse shear load at 20° inclination of laminate leads to reduction in residual compressive strength. Moreover, uni-directional glass/epoxy laminates have better residual compressive strength than cross-ply laminates for both 2 mm and 3 mm indentation displacements.

[Retracted] Effect of the Reinforcement Phase on Indentation Resistance and Damage Characterization of Glass/Epoxy Laminates Using Acoustic Emission Monitoring

“…AE energy, amplitude, counts, rising angle (RA), duration, and peak frequency were utilized by Kumar et al [17] to characterize damage mechanisms in glass/carbon/epoxy composite laminates. Only a few studies have used QSI loading with AE monitoring to simulate LVI behavior and evaluate damage initiation and progression [18].…”

The effect of adhesively bonded external hybrid patches on the residual strength of repaired glass/epoxy‐curved laminates

“…The damaged surface area was visualized using a backlight picture setup and measured using Image-J software, which calculates the surface diameter caused by indentation loading as shown in Figure 2B,C. 17 A bench drilling machine is used to create holes for repair after removing damaged composite samples. The holes are optimized using 8, 10, and 12 mm drills.…”

“…15,16 This damage may manifest itself in a variety of ways, including cracking, debonding, and breaking, all of which have an impact on the composite's strength and stiffness. Jayababu et al 17 examined the indentation resistance of UD and CP GFRP laminates. UD laminates decrease residual compressive strength, while CP laminates increase damage development.…”

Experimental Investigation on the Effect of Stacking Sequence on Damage Resistance and Post-indentation Performance of Glass/Epoxy Laminates Under Different Loading Planes Using Acoustic Emission Monitoring

“…This type of impact damage was simulated by conducting quasi-static indentation (QSI) loading on the composite structures 7 . Moreover, Yuichiro et al 8 stated that the significant reduction of structural strength in laminated composites is mainly due to the severity of impact induced damage; it may be invisible during routine visual inspection methods 9 .…”