Chip formation in machining of unidirectional carbon fibre reinforced polymer laminates : FEM based assessment

Finite-element (FE) method offers a low cost virtual alternative to assist in optimisation of critical process parameters in machining of composites. This study is focussed on understanding the mechanics of chip formation in orthogonal cutting of unidirectional (UD) carbon-fibre-reinforced polymer (CFRP) laminates through development of FE models. Machining responses of UD CRFP laminates with fibre orientation of 45° (measured with respect to the cutting direction) are assessed. Modelling of material removal in the form of fragmented chips is considered. Damage initiation is determined using the Hashin stress criterion for the fibre component, while matrix failure predicted using Puck criteria. Subsequent damage evolution events are modelled using a strain-based softening approach to degrade relevant material properties linearly. Primary numerical results compared with experimental data revealed that developed FE models are able to predict global machining responses (i.e. cutting forces) and characterise various discrete damage modes associated with machining response of quasi-brittle CFRP laminates successfully. The models also provide a valuable insight into variation in chip morphology.