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Dr Fernando Cepero

Graduated 2021

In order to make the election of the cutting parameters in a machining process with composite material saving money and time in a secure way the development of a finite element simulation is recommended. In that way, a good estimation of the results at the end of the process for the tool used and the material can be obtained without doing any kind of test. It helps to reduce the number of experiments necessary for obtaining a good optimisation of the machining process saving an important amount of time and money.


Delamination damage is one of the side effects of machining Carbon Fibre Reinforced Polymer (CFRP) composites particularly when using the wrong cutting parameters or a worn drill. Delamination can result in severe damage and failure, so being able to accurately predict and counteract damage under different cutting conditions is a significant advantage for composite manufacturers.


Finite element modelling of drilling of CFRP composites is a recognised methodology for damage prediction. However, the computational cost of the currently used sophisticated models is high. In this project, simplified models based on a relatively novel EXtended Finite Element Method (XFEM) strategy will be developed and compared in terms of delamination prediction with the more complex models. For example, the project will investigate whether the simplified model, presenting reduced computational cost, slightly overestimates the delamination factor when compared with the complex model.


The influence on delamination of thrust force, clamping area at the bottom surface of the laminate and the stacking sequence will also be investigated using both models. This is a 4 year PhD studentship funded by the Department of Mechanical Engineering and EPSRC. 


Cepero, F, J. Justo, I.G. García, V. Mantič, Experimental comparison between the transverse fracture toughness corresponding to either longitudinal or transverse growth, Proceedings of the 16th European Conference on Composite Materials (ECCM16), Seville, 5 pages, CD, 2014

Cepero, F, J. Justo, I.G. García, V. Mantič, F. París, A. Barroso, Experimental comparison of the transverse fracture toughness in unidirectional laminates corresponding to longitudinal or transverse crack growths, XI National Conference on Composite Materials(MATCOMP15), Madrid, pp. 1165-1170, 2015

Cepero-Mejias, F., Phadnis, V.A., and Curiel-Sosa, J.L. 2019. ‘Machining induced damage in orthogonal cutting of UD composites: FEA based assessment of Hashin and Puck criteria’. Procedia CIRP 82, 332-337.

Read paper here

Cepero Mejias, F., Curiel Sosa, J.L., and Phadnis, V.A. 2018. ‘Machining 2D FEM Study of Long Fibre Reinforced Unidirectional Laminates Using a Linear Continuum Damage Technique’. 6th Conference on Computational Mechanics, Glasgow, UK, 11-15 June 2018.

Read paper here