Finite Element Analysis of Drilling of Carbon Fibre Reinforced Composites
Ozden Isbilir & Elaheh Ghassemieh
Abstract Despite the increased applications of the composite materials in aerospace due to
their exceptional physical and mechanical properties, the machining of composites remains
a challenge. Fibre reinforced laminated composites are prone to different damages during
machining process such as delamination, fibre pull-out, microcracks, thermal damages.
Optimization of the drilling process parameters can reduces the probability of these
damages. In the current research, a 3D finite element (FE) model is developed of the
process of drilling in the carbon fibre reinforced composite (CFC). The FE model is used to
investigate the effects of cutting speed and feed rate on thrust force, torque and
delamination in the drilling of carbon fiber reinforced laminated composite. A mesoscale
FE model taking into account of the different oriented plies and interfaces has been
proposed to predict different damage modes in the plies and delamination. For validation
purposes, experimental drilling tests have been performed and compared to the results of
the finite element analysis. Using Matlab a digital image analysis code has been developed
to assess the delamination factor produced in CFC as a result of drilling.
Carbon fibres reinforced composites . Polymer matrix composites . Delamination . Finite element analysis . Drilling . Cohesive zone
In this study, a mechanical Lagrangian finite element formulation is used to simulate the
drilling process of unidirectional carbon fibre reinforced laminated composite material. The
effects of cutting parameters, namely cutting speed and feed rate, on drilling are
investigated by the proposed FE model. Experimental validation tests were performed;
and the thrust force and torque were experimentally measured throughout the process. In
addition to that delamination at the entrance of the holes was experimentally observed and
digital analysis of the images was carried out. Delamination factors were identified.
The results show that cutting parameters have a significant influence on the stress, thrust
force, torque and delamination. The thrust force is slightly underestimated whereas torque
and delamination are overestimated. Results clearly show that the induced thrust force,
torque and delamination increase with the feed rate and decrease with the cutting speed.
This study can justify that the finite element simulation technique is a feasible, accurate
and parametric analysis method which can be used in the drilling process. For the future
studies related to drilling process, a thermo-mechanical model is needed. Having an
appropriate friction coefficient and an improved friction model for the different regimes of
tool and work piece interfaces would also provide better predictions.
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