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This article addresses the influence of cutting parameters on drilling-induced delamination of woven glass fiber-epoxy composites reinforced with functionalized multi-walled carbon nanotubes (MWCNTs). The input parameters include feed rate, cutting speed, drill size, and wt. % carbon nanotubes present in nanocomposite laminates. Experiments were conducted based on Taguchi L16 orthogonal array and analysis of variance was conducted to determine the significance of each parameter. The results indicate that the main effects of nano content, feed rate, and spindle speed are significant, while the effect of drill diameter is negligible. Furthermore, the optimum drilling conditions for minimum delamination were determined according to the Taguchi’s S/N ratio analysis.

Characterization of dynamic induced damage is one of the most controversial issues in the application of composite structures. To this aim, Acoustic Emission (AE) technique has been qualified as a robust tool for damage sequence analysis due to its high sensitivity to damage mechanisms. First, AE reference map was created using a couple analysis of Fuzzy C-Means (FCM) clustering and Principal Component Analysis (PCA). The low velocity impact tests were then conducted on composite plates. Finally, Impact AE signals were discriminated and the sequence of damage mechanisms during impact process was discovered. As a result, it is concluded that AE method accompanied with the presented method is a new appropriate approach to discriminate damage mechanism sequences in impacted composite specimens.

In this paper, the effect of preload on impact response of composite laminates is considered. To this aim, three specimens were manufactured and tested under 4 different impact conditions: 1- A curved laminate without preload. 2- A preloaded curved laminate, showing a lower radius of curvature due to the preload. 3- A curved laminate without preload but initial reduced curvature. The particular test conditions studied here allow estimating and discerning the effect of pre-stress and curvature on the impact response. Results show that the preload leads to an increased curvature, to which it follows that the maximum impact force and the damaged area increase significantly. The comparison of the impact response of the second and the third specimens show that, in the case of similar curvature, the preload leads to a lower damaged area. These results are particularly important for designing of curved composite components.