Drilling and structural property study of multi-layered fiber and fabric reinforced polymer composite - a review

Fiber-reinforced polymer (FRP) composites are widely being used for structural applications due to their attractive properties. Particularly, to fabricate complicated structures by FRP composites, joining composite structure elements through fasteners require drilled holes. More than 60% of the structural FRP components are rejected owing to poor quality of holes. The FRP composites are heterogeneous due to multi-layer architecture, multi-phase material combinations, and hybridization. Hence, while drilling the behavior of FRP composites depends on various machining and tool parameters in addition to workpiece properties. As a result of drilling, the quality of drilled holes deteriorates due to delamination, matrix crack, matrix burning, fiber pull-out, buckling, spalling, and fuzzing in the drilled hole zone. To minimize all these defects researchers tried to design material, tool and machining parameters and reported. In this paper, the authors have made an attempt to summarize up-to-date progress in structure properties and drilling study of unidirectional and bidirectional multi-layered composites, three-dimensional fabric-reinforced composite and hybrid composite and similarly, emphasize the advanced characterization techniques to investigate the drilled hole quality. In addition, cryogenic assisted drilling, lubricated drilling, and micro-drilling literatures have been discussed. Based on the literature, conclusions and future scope have been reported.