Pebble/epoxy-based composites: mechanical and dynamic study

The study was focused to develop a novel epoxy pebble (EP) composite based machine tool structures with a higher compressive strength and damping ratio. The impact on compressive strength and damping ratio by the addition of 15%, 25% and 35% (by weight) epoxy resin binder to the EP composite has been determined. The weight percentage of pebble epoxy, aggregate size, curing time and size of microfillers were considered as input process parameters in this study. The results showed the drop in compressive strength with respect to increases in the aggregate size. The composite comprises of 15% (by weight) epoxy resin and 85% pebbles showed the maximum compressive strength at 103.96 ± 0.1 MPa and damping ratio at 0.0169. The damping ratio has been assessed by an experimental modal analysis using a half power bandwidth approach. The damping ratios of EP composites are found to be 5 to 10 times higher than that of cast iron. The analysis results of variance and S/N ratio indicated the contribution of pebbles in the formation of composites as the most influential factor. Confirmatory experiments have been conducted and the results are in good agreement with the experimental findings. The X-ray diffraction (XRD) results showed the presence of silicone oxide, quartz, nickel oxide, lithium niobium arsenide, cobalt oxide, boron nitride and silver cerium indium as major phases in the EP composites developed. Major elements are presented and peak angles are identified. SEM analysis revealed that pebbles and microfillers were uniformly mixed with epoxy resin. Hence, it is found that the application of EP composite rather than conventional machine tool structures can increase the service life of machine tool structures significantly. Graphical abstract