Determinations and performance investigations of hybrid composite properties for hydrokinetic turbine blades

Abstract

In this experimental study, hybrid composite properties for hydrokinetic turbine blades were determined, and its performance was examined. The reinforcements included glass fiber, treated and untreated highland bamboo fiber, reinforced polyester-based composites and their hybrid composites, as well as row bamboo (bamboo culm). The row bamboo was prepared on the bamboo culm’s outer surface to get rid of any leftovers, before cutting in accordance with the specimen test standards. In order to make hybrid composite materials, polyester resin was mixed with fibers in the proportions of bamboo fiber/glass fiber (50%/50%), and fiber/matrix (30%/70%). The composite containing glass fiber has a flexural strength that is 12% and 21% higher than materials reinforced with alkali-treated and untreated highland bamboo fiber reinforced composites respectively. The alkali treatment of highland bamboo fiber improved its physical-mechanical properties, making it suitable for use different application. Alkaline treatment boosts the composite’s tensile and compressive strength by 37% and 3.4% for composite reinforced with untreated bamboo fiber, and 10.2% and 23.8% for composite reinforced with glass fiber, respectively. The fiber density of highland bamboo was increased by removing less dense non-cellulosic components (hemicellulose and lignin). However, the fiber’s moisture absorption is the main issue in using it in a composite that works submerged in water. This study investigated whether incorporating glass fiber in highland bamboo-glass fiber polyester hybrid composite reduces the composite material’s water uptake. A reduction was found, however, the density was increased. It is challenging to employ row bamboo for the construction of hydrokinetic turbine blades as water ingress of the composite must be avoided even in the presence of erosion caused by cavitation and impact with foreign bodies in the water.