Impact Response of Composite Sandwich Cylindrical Shells

Abstract

Nowadays, due to the complexity and design of many advanced structures, cylindrical shells are starting to have numerous applications. Therefore, the main goal of this work is to study the effect of thickness and the benefits of a carbon composite sandwich cylindrical shell incorporating a cork core, compared to a conventional carbon composite cylindrical shell, in terms of the static and impact performances. For this purpose, static and impact tests were carried out with the samples freely supported on curved edges, while straight edges were bi-supported. A significant effect of the thickness on static properties and impact performance was observed. Compared to thinner shells, the failure load on the static tests increased by 237.9% and stiffness by 217.2% for thicker shells, while the restored energy obtained from the impact tests abruptly increased due to the collapse that occurred for the thinner ones. Regarding the sandwich shells, the incorporation of a cork core proved to be beneficial because it promoted an increase in the restored energy of around 44.8% relative to the conventional composite shell. Finally, when a carbon skin is replaced by a Kevlar one (hybridization effect), an improvement in the restored energy of about 20.8% was found. Therefore, it is possible to conclude that numerous industrial applications can benefit from cylindrical sandwiches incorporating cork, and their hybridization with Kevlar fibres should be especially considered when they are subject to impact loads. This optimized lay-up is suggested because Kevlar fibres fail through a series of small fibril failures, while carbon fibres exhibit a brittle collapse.

Damage mechanisms in composite laminated shells subjected to multiple impacts at different points

“…These curves are representative of all the conditions tested, and are characterized by containing oscillations that can be attributed to the propagation of elastic waves, resulting from the specimen's vibrational response 33,34 . Furthermore, the curves show a profile that agrees with others reported in the literature for similar semi‐cylindrical composite shells 25–28,35,36 . In more detail, Figure 2 shows an increase in the impact force until it reaches a maximum value, peak force, followed by a somewhat abrupt decrease, depending on the point of impact.…”

“…33,34 Furthermore, the curves show a profile that agrees with others reported in the literature for similar semicylindrical composite shells. [25][26][27][28]35,36 In more detail, Figure 2 shows an increase in the impact force until it reaches a maximum value, peak force, followed by a somewhat abrupt decrease, depending on the point of impact. Conversely, the energy-time curves represented…”

Cylindrical Sandwich Shells for Civil Engineering Applications

“…In fact, the glass fiber composites fail on the tension side, while the carbon fiber composites primarily fail on the compression side [11]. In terms of impact response, Figure 3 shows typical force-time curves obtained from the impact tests, which present a similar profile to those described in the literature [10,12]. The observed oscillations are caused by the vibrations of the specimen and depend on both the stiffness and mass of the specimen and impactor [13,14].…”

Curved grid‐scored foam core sandwich composites under low‐velocity impact loads: Effects of curvature, stacking sequence, and core finishing

“…From the literature review, although it has extensive application in a variety of engineering applications, there is a lack of studies on the LVI behavior of curved sandwich panels. Reis et al reported that incorporating single‐sided Kevlar layers into sandwich cylindrical shell composites could improve LVI impact strength and elastic energy recovery 23 . Albayrak, et al compared experimentally and numerically the effects of different surface geometries on the LVI responses of curved sandwich composites produced by introducing rubber between glass fiber woven fabrics.…”

“…Reis et al reported that incorporating single-sided Kevlar layers into sandwich cylindrical shell composites could improve LVI impact strength and elastic energy recovery. 23 Albayrak, et al compared experimentally and numerically the effects of different surface geometries on the LVI responses of curved sandwich composites produced by introducing rubber between glass fiber woven fabrics. It was seen that, compared with flat plates, curved sandwich plates showed wider delamination areas as well as lower impact strength.…”