The effect of support on multi-hole drilling for glass fiber-reinforced plastic composite materials

Abstract

Mechanical joint of fastener is widely used in the assembling and repairing of the modern aircraft composite components, so multi-row holes are needed in jointing, and their quality directly influences the reliability of aircraft structures. So, multi-hole drilling of composite components becomes one of important processes. A large number of researchers have carried on the detailed and thorough research for the drilling process and corresponding damage based on single-hole drilling of composite materials, but none corresponding research was based on multi-hole drilling of composite materials. In the case of a round-hole array backing plate and a square-hollow backing plate as supporting, this paper carried out finite element simulation, theoretical analysis, and experimental research for multi-hole drilling of glass fiber-reinforced plastic (GFRP) composite materials. The study aimed at contrasting and analyzing S33 stresses, thrust forces, and exit delamination damage of multi-hole drilling between the two kinds of support cases and between the internal of each support case. The results showed that S33 stresses, thrust forces, and exit delamination damage existed significant difference between two kinds of support cases. What is more, S33 stresses, thrust forces, and exit delamination damage have no difference with a round-hole array backing plate as supporting; under a square-hollow backing plate as a support, S33 stresses, thrust forces, and exit delamination damage existed significant difference with the changing of straight-line distances from the center of hole to the center of backing framework. On the basis of this study, the analytical results provided corresponding theoretical guidance for the multi-hole drilling in the assembling and repairing for the composite components.