Comparative analysis of drilled and molded holes in short natural fiber reinforced composites

Abstract

Recently, the demand for natural fiber based composite products as compared to synthetic fiber based products has increased manifold due to their salient characteristics, such as biodegradability, non-toxicity, and sustainability. Hole-making is an inevitable operation to ascertain the structural integrity of complex composite products. Thus, a comparative assessment has been reported between the molded and drilled holes in two types of composites, that is, aloe vera fiber and banana fiber based epoxy composites. The performance of fabricated composites was compared based on load bearing capacity under tensile loading conditions. The molded hole specimens recorded 10.7% (aloe vera based) and 17.2% (banana fiber based) higher failure load as compared to the drilled hole specimens of similar type of composites. The aloe vera fiber based composite specimens, such as, specimens without hole, molded hole, and drilled hole, recorded higher failure load (102%, 45.6%, and 54.1%, respectively) as compared to banana fiber based composites. The quality of molded and drilled holes (before and after fracture) was also assessed using stereomicroscope and field emission scanning electron microscopy images. The microstructural assessment helped to correlate the variation in the mechanical properties of tested specimens with the quality of the holes produced. This study also revealed that the molded hole specimens have better hole quality than the drilled hole specimens in case of both types of composites. The defects like sharp edges, burrs, cracks, and uncut fibers were found to be absent in case of molded hole specimens. Whereas, these defects create the stress concentration zone in drilled hole specimens which is responsible for their lower strength values.