Investigations on mechanical and sliding wear behaviour of short fibre-reinforced vinylester-based homogenous and their functionally graded composites

摘要

Now-a-days, short fibre-reinforced functionally graded polymer composites are used in numerous structural applications. This article presents the investigation on mechanical and sliding wear characteristics of short Kevlar fibre-reinforced vinylester resin homogenous and its functionally graded polymer composites. The composites are fabricated by simple mechanical stirring (for homogeneous) and vertical centrifugal casting technique (for graded), respectively. Among the investigated physical and mechanical characteristics, the characteristics like void-fraction, hardness and flexural strength are found to be enhanced in the case of functionally graded materials than homogeneous composites, and this increases with fibre loading. Similarly, the characteristics like tensile strength and impact strength are found to be deteriorated in case of functionally graded materials than homogeneous composites, and this increases with fibre loading. At the end, dry sliding wear behaviour are determined experimentally on pin-on-disk type friction and wear monitoring test rig, under abrasive medium environment. The designed parameters used are sliding velocities (1.5-4.5 m/s), fibre loading (0-20wt%), normal loads (10-25 N), sliding distance (1-4km) and abrasive grit size of 18-48 urn that creates abrasive medium. It is observed that for similar test conditions functionally graded materials exhibit much higher wear resistance than homogeneous composites. Sliding wear characteristics and their significant factor settings are successfully analysed using statistics-based Taguchi experimental design. Finally, dynamic mechanical properties of the investigated homogenous/functionally graded materials composites are studied in order to investigate the overall flexibility and interaction of the constituents, so as to improve the specific wear rate. Storage modulus of the composites improves with Kevlar fibre loading. Graded composites in most cases exhibits higher storage modulus than homogeneous composites. Surface morphology studies reveal the dynamics of erosion wear and underlying micro-mechanisms that serve as determinant for wear performance of such composites.