Mechanistic force modelling in drilling of AFRP composite considering the chisel edge extrusion

Abstract

Aramid fiber reinforced plastic (AFRP) composites have been widely used in automotive, aerospace, and defense industries. The common AFRP drilling process tends to cause damage to the composite structures which subsequently affects their fatigue lives and in-service performance. Understanding the mechanism of cutting forces generation is crucial in controlling the cutting process for achieving desired hole quality and machining accuracy. This study proposes a novel mechanistic model considering both the cutting action and the extrusion action of the chisel edge. For the first time, the extrusion force generated by the chisel edge has been considered as a rigid wedge penetrating into an elastic half space based on the Hertz contact theory. The total thrust force in AFRP drilling is divided into three components: i) thrust force generated by the cutting lips, ii) thrust force generated by the chisel edge cutting action, and iii) extrusion force generated by the chisel edge extrusion action. The proposed model was then validated by experiments and data was compared with the case where extrusion was not considered. The results show that our novel mechanistic model can provide a more accurate thrust force prediction. The average error of our model was 2.54% against the experimental data, whereas the error seen in conventional model without accounting extrusion was 8.22%. This suggests that the chisel edge extrusion plays a significant part in the drilling of AFRP, and hence confirms the necessity of considering extrusion in establishing the associated mechanistic model.

Thermo-Mechanical and Delamination Properties in Drilling GFRP Composites by Various Drill Angles

“…As the case in hand at speed 400 rpm, feed 0.2 mm/r and thickness of 2.6 mm, the variation in drill point angle from 100° to 118° to 140°, and the delamination factor increased from 1.49 to 1.53 to 1.62, respectively. The same observation has been reported [ 4 , 41 ]. It is also noted that the delamination factor is proportional to feed and speed.…”

“…Bayraktar and Turgut [ 4 ] presented the influence of drill point angle on delamination of C/C/Al 6013-T651 stacks with uncoated and coated drills and concluded that uncoated drill has better performance than coated drill according to delamination criterion. Liu et al [ 41 ] proved that the thrust force produced by extrusion of the chisel edge is greater than that generated by cutting the chisel edge. Shu et al [ 42 ] conducted a comprehensive comparison between the dedicated and conventional drill bit designs from various views, such as thermal, mechanical, and chip formation.…”

Study on Burr Formation and Tool Wear in Drilling CFRP and Its Hybrid Composites

“…Therefore, in order to restrain the delamination damage, it has great significance to predict the thrust force at the beginning of the delamination and to control the thrust force during the drilling process. The total thrust force is divided into three components in the drilling of polymer composite materials: (i) thrust force generated by the cutting lips; (ii) thrust force generated by the chisel edge cutting action; (iii) extrusion force generated by the chisel edge extrusion action [47]. Figure 8 illustrates the effects of the number of holes drilled on the thrust force.…”

An analytical delamination model of drilling aramid fiber–reinforced plastics by brad drill

“…To date, drilling is still considered as the most pivotal hole-making process in composite component assemblies due to its cost effectiveness [2]. However, drilling of AFRP remains a challenge due to the inherent anisotropic multiphase structure of the material [3]. Drilling-induced damages, such as thermal degradation, fiber bundle tearing, and delamination, are common in the AFRP hole making processes.…”