Mixed-mode fracture of sandwich composites: Performance improvement with multiwalled carbon nanotube sonicated resin

Abstract

An experimental investigation on sandwich composite materials composed of glass-fiber face sheet and polyvinyl-chloride foam core has been carried out. The research demonstrates improvement in mixed-mode delamination fracture toughness values of samples under mixed-mode bending condition. The improvement is recorded with addition of a certain percentage by weight of multiwalled carbon nanotubes in comparison to conventional samples. An easy and cost-effective methodology of multiwalled carbon nanotube insertion through sonication of epoxy resin followed by mixing with hardener and vacuum resin infusion technology for manufacturing of sandwich composites has been utilized in this study. The study also identifies the optimum weight percentage of multiwalled carbon nanotube addition in the resin system for maximum performance gain in mixed-mode fracture toughness. The results of observations in this study have been supported by field emission scanning electron microscope studies as well as high-resolution transmission electron microscope analysis.

Interfacial delamination in glass-fiber/polymer-foam-core sandwich composites using singlemode–multimode–singlemode optical fiber sensors: Identification based on experimental investigation

“…The sample is casted through hand lay-up technique with the prepared resin system and allowed to cure for more than 48 h at room temperature (25℃). It should be noted that there are many other methods of sample casting such as vacuum resin infusion as done by authors [1–4], but those advanced techniques have not been used in this research since the objective of this paper was to determine the suitability of this sensor methodology as an effective delamination detection technique. Initial delamination in the form of pre-crack required at one end for the modified delaminated DCB sample is introduced by coating the upper surface of the core (just below the lower surface of the face sheet) with 80 µm thick non-stick impermeable Teflon sheet as shown in figure.…”

“…In spite of numerous benefits, one of the major problems of these structures is the propensity for interfacial delamination between the face sheet and the core material which may be either due to manufacturing defects or may occur during service (such as a result of some low velocity impact). These interfacial defects might eventually propagate as a result of normal loading conditions which the structure or component might encounter in service (refer to literature by the author [1–4] as well as literature cited within those papers). Therefore, there is a need to track interfacial delaminations in real time, while the structural component is in service.…”

Fabrication and Thermo-Electro and Mechanical Properties Evaluation of Helical Multiwall Carbon Nanotube-Carbon Fiber/Epoxy Composite Laminates

“…The source of such delamination between the composite layers is due to imperfections (e.g., micro-cracks) caused during the fabrication process. Such micro-cracks start to propagate in regions where comparatively higher void proportions exist under fatigue, impact stresses, and transverse loading conditions, or from different environmental factors [19][20][21]. On the other hand, FE simulations have been used to determine the interlaminar and matrix cracking failure process in HMWCNT-laden composite laminates.…”

“…Furthermore, interlaminar delamination is one of the most significant challenges in the design of any structural composite [ 7 ]; others include a large number of design variables, problems related to the topology optimization of composite structures, specific non-linear behaviors of laminated structures, and uncertainties on the mechanical properties of composites, among others [ 7 , 16 , 17 ]. Brittle fractures originate in the matrix-dominated interlaminar area from fiber–matrix interface de-bonding and transverse matrix cracking, which rigorously influence the composite laminate structural integrity [ 18 , 19 ]. The source of such delamination between the composite layers is due to imperfections (e.g., micro-cracks) caused during the fabrication process.…”

Low Velocity Impact Behaviour of Carbon/XPS Sandwich Composites

“…To date, only a limited number of studies have investigated the effect of CNTs on flexural properties or fracture toughness of sandwich composites [17,18]. However, much less is known about how CNT affects impact resistance of sandwich composites.…”