Mechanical properties and energy absorption capability of thin-walled square columns of silica/epoxy nanocomposite

Abstract

In this paper, the effect of adding silica nanoparticle to epoxy, silica weight percent, particle size and various combinations of epoxy/silica on Young’s modulus, yield strength and energy absorption capability of thin-walled square columns was investigated. Two different sizes of silica nanoparticles, nominally<br><br>17 nm and 65 nm in diameter, were used. Nanosilica particles were dispersed almost homogeneously<br><br>in the epoxy resin from 1.5 wt.% to 6 wt.% in three series of composites. First and second series were composites reinforced with 17 nm and 65 nm particle size, respectively and third series were composites<br><br>reinforced with combination of both particle sizes. All specimens were tested under quasi-static loading<br><br>using a servohydraulic Instron machine. A scanning electron microscopy (SEM) was used for fracture surface studies. The results showed that when silica weight percent was increased, the Young’s modulus<br><br>increased, yield strength remained constant and energy absorption capability of columns decreased,<br><br>and specimens collapsed under unstable and dangerous mode. It was observed that the reason for this<br><br>type of collapse was initiation of axial cracks at an early stage of the loading and propagation along<br><br>the specimen height. Energy absorption capability for columns with height of 60 mm and 90 mm was<br><br>also investigated and results showed that this parameter for shorter specimens was higher in the same<br><br>combination of a nanocomposite. Moreover, the effect of particle size on Young’s modulus, yield strength<br><br>and energy absorption capability was not considerable. Using both particles in a combination did not<br><br>show any important synergy effect. And finally, fracture surfaces of the specimens showed that surface<br><br>roughness was increased by increasing the silica nanoparticles.