Abstract
In this study, three differently-configured sandwich structures were manufactured with three different core materials: Balsa wood, Tycor and Polyethylene terephthalate (PET). Glass-Fibre Reinforced Polymer (GFRP) skins were used to understand the effects of different types of core materials on the flexural behavior of sandwich composites under four point bending (4PB) condition, using digital image correlation (DIC). DIC is one of the most outstanding techniques to understand the mechanical behavior of the structure during the test, thus defining any problematic regions in the structures. The failure mechanisms of the structures were observed by using strain maps of the structures. The results show that the sandwich structure with Balsa wood as a core material has the highest stiffness; however, catastrophic failure appeared in the early stages of the test. The sandwich structure with PET and Tycor exhibited very similar behaviour under load.
Highlights
Sandwich composites are commonly used in naval, aviation and energy applications [1,2,3,4]
Balsa wood is used as the core materials especially wind turbine blades
Sandwich composites were manufactured with honeycomb core with various densities of 55 kg/m3 and 82 kg/m3of aluminium core and 48 kg/m3 of aramide fibre core were tested through a 4PB test
Summary
Sandwich composites are commonly used in naval, aviation and energy applications [1,2,3,4]. The microstructure of the foam was more dominant in influencing the flexural property of the sandwich structure than the density of the core material. Manalo et al studied on flexural mechanical properties of the noval sandwich composite manufactured with glassfibre reinforced polymer skins and modified phenolic core materials through 4PB tests in flatwise and edgewise. They reported that the sandwich composites were broken abruptly under load in flatwise position. To obtain a better understanding of the response of the sandwich structures, Digital Image Correlation (DIC) was used This technique tracks a domain of points in an image series captured throughout the test, using the first image of the series as a reference. The deflections were shifted by a constant value to ensure a directly proportional relationship with the shear stress within the 300 to 500 kPa range; this was required to discount for the extra compliance provided at the beginning of each test by rubber pads placed between the pins and the surface of the specimen, used to avoid ply damage of the latter
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