Influence of neighbouring damage on delamination growth in multiple indented composites. (March 2023)

• Record Type: Journal Article
• Authors: Huo, L.; Kassapoglou, C.; Alderliesten, R.C.
• Is Part Of: Materials & design. Volume 227(2023)
• Publication Date: 2023-03
• Subjects: Polymer-matrix composites -- Quasi-static indentation -- Delamination growth -- Delamination link-up; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2023.111723
• Languages: English
• ISSNs: 0264-1275

Abstract

Graphical abstract: Highlights: The effect of the neighbouring pre-existing damage on delamination growth is quantified using a proposed stress-based delamination growth prediction method. The stress field is determined using a finite element model, and damages are detected and quantified through ultrasonic scanning and optical microscopy. The delamination that occurs second in the multiple-indented composite laminate is more likely to propagate at the ply interface. The more easily propagated delamination could result from a degradation of the delamination growth threshold caused by the presence of the neighbouring damage. Abstract: To improve current design approaches for composite structures, it is required to further investigate the damage interaction effects of composite materials under multiple out-of-plane concentrated loads. It is first necessary to comprehend the dependence of the effective delamination threshold, which describes whether a delamination grows on pre-existing delamination damage in composite laminates. A combined experimental and numerical study is presented, in which two sequential out-of-plane quasi-static indentations are applied to fully clamped composite laminated panels, with changing distances between the two indentation locations changing. The results show that the second indentation delamination is more likely to propagate, particularly in the straight-line direction from the second indentation site to the first one, which can be interpreted as a decrease in the effective delamination threshold associated with microcracks ahead of the delamination front. The relevant percentage reduction is 37% and is independent of the imposed indentation load. As a crucial take-away, designers should be mindful that the damage interaction effects could result in greater damage than the sum of the individual cases.