# A Novel Finite Element Method Approach in the Modelling of Edge Trimming of CFRP Laminates
## 6 Conclusions  
In this research, we developed a novel study for the modelling of edge trimming of CFRP laminates using a worn cutting tool. The tool wear effect on machining forces was successfully modelled in 45\({}^{\circ}\) and 90\({}^{\circ}\) laminates. A composite damage algorithm based on the hybrid Puck-Maximum stress criteria was used to calculate damage initiation with a linear energy-based degradation of the mechanical properties and to mimic composite behaviour. Validation of average machining forces predictions was achieved by obtaining relatively small errors (within 10%) compared to experimental data. These predictions notably enhance the numerical results achieved in previous investigations in this matter. These improvements are obtained because of the numerical implementation of the spring back phenomenon, which adds to the simulation machining forces. Several relevant conclusions extracted from this study are summarised in the below bullet points. * In all developed simulations, the normal forces (\(F_{N}\)) simulated are much higher than the tangential forces (\(F_{T}\)); meaning that spring back forces are predominant to the cutting forces in these analyses. * The rise observed in \(F_{N}\), \(F_{X}\), and \(F_{Y}\) is result of the increment of spring back forces, while \(F_{T}\) keeps stable because the increment of the spring back and frictional forces is compensated for. * Increments in \(F_{Y}\) caused by tool wear were observed to be more severe than increments in \(F_{X}\). Therefore, the evolution of vertical forces should be investigated to determine the appropriate timing to replace worn inserts. * A steady increase in normal (\(F_{N}\)) and vertical (\(F_{Y}\)) average forces because the effect of the tool wear was observed in both studied laminates. These increments are more severe in 90\({}^{\circ}\) laminates. * Normal and tangential machining forces depict a steady rise in 45\({}^{\circ}\) laminates. This happens because the range of machining relative angles from 45\({}^{\circ}\) to \(-\)15\({}^{\circ}\) does not modify the spring back force significantly, nor cutting forces. Therefore, this rise is governed by the progressive increment of the depth-of-cut when the cutting tool tooth advances. * Normal machining forces of 90\({}^{\circ}\) laminates have an initial steep rise to later fluctuate between a stable value. In the normal force, the cutting tool tooth is pushing down the laminate parallel to the fibre, finding a high contact rigidity that decreases significantly when the machining relative angle is far from this 90\({}^{\circ}\). Note that interesting technical applications could be achieved using the FE model developed in this investigation. For instance, it could detect the point where the tool should be replaced, thus saving manufacturing time and optimising the tool's use. Apart from this point, another analysis could be developed using this framework. The FE model developed in this research offers an excellent capability to analyse how other relevant cutting parameters such as feed rate, cutting speed, fibre orientation, or rake and relief angles affect the machining forces. Therefore, this FE model or similar FE models can be used in oncoming composite milling investigations to quantify the effects of cutting edge rounding and CFRP machining failure mechanisms. Conceptualization, J.L.C.-S. and K.K. ; methodology, F.C.-M. and N.D.; software, F.C.-M.; validation, N.D. and F.C.-M. formal analysis, N.D.; investigation, F.C.-M.; resources, N.D. and K.K. ; data curation, N.D.; writing--original draft preparation, F.C.-M.; writing--reviewand editing, F.C.-M.; visualization, F.C.-M.; supervision, J.L.C.-S., K.K. and V.A.P. ; project administration, F.C.-M.; funding acquisition, J.L.C.-S. and K.K. All authors have read and agreed to the published version of the manuscript. This research was funded by EPSRC grant number EP/L016257/1. The APC was funded by The University of Sheffield. Not applicable.