Title: Drilling thick composite materials using large diameter drills

Authors: Pierre Rahme, Yann Landon, Pierre Lagarrigue, Frederic Lachaud, Robert Piquet

Addresses: Department of Mechanical Engineering, Universite de Toulouse, INSA, UPS, Mines Albi, ISAE; ICA (Institut Clement Ader), Bat 3R1, 118 Route de Narbonne, F-31062 Toulouse cedex 9, France. ' Department of Mechanical Engineering, Universite de Toulouse, INSA, UPS, Mines Albi, ISAE; ICA (Institut Clement Ader), Bat 3R1, 118 Route de Narbonne, F-31062 Toulouse cedex 9, France. ' Department of Mechanical Engineering, Universite de Toulouse, INSA, UPS, Mines Albi, ISAE; ICA (Institut Clement Ader), Bat 3R1, 118 Route de Narbonne, F-31062 Toulouse cedex 9, France. ' Department of Mechanical Engineering, Universite de Toulouse, INSA, UPS, Mines Albi, ISAE; ICA (Institut Clement Ader), Bat 3R1, 118 Route de Narbonne, F-31062 Toulouse cedex 9, France. ' Department of Mechanical Engineering, Universite de Toulouse, INSA, UPS, Mines Albi, ISAE; ICA (Institut Clement Ader), Bat 3R1, 118 Route de Narbonne, F-31062 Toulouse cedex 9, France

Abstract: Composite materials are widely used in aeronautical structures. Assembling the various parts involved requires machining operations, especially drilling. When drilling, a number of defects that diminish the structure breaking strength are propagated. Delamination on hole exit is considered to be the main such defect, this being directly related to the drilling axial force. Determining the drilling critical thrust force at delamination is thus crucial. A number of studies have been conducted into this question but are only applicable to small diameter drilling operations cases. This paper proposes an orthotropic analytical model with the aim of calculating the drilling critical thrust force with a large diameter drill. New assumptions are then proposed. The plate element located under the cutter is broken down into a number of zones in relation to the cutter different active parts. A digital model is developed to validate analytical modelling. Punching tests were also conducted to validate the choices of boundary conditions.

Keywords: drilling; thick composite materials; delamination; pilot holes; analytical models; numerical modelling; aeronautical structures; critical thrust force; drilling thrust force; large diameter drills; punching tests; boundary conditions.

DOI: 10.1504/IJMMM.2011.042191

International Journal of Machining and Machinability of Materials, 2011 Vol.10 No.3, pp.202 - 221

Published online: 31 Aug 2011 *

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