#Removing elements on polytool crack

#Removing elements on polytool crack

After the first crack initiation, further potential cracks are considered in the modelling approach, being affected by the varying tool-fibre contact point with progressing cutting motion. In the third sub-model (3) with the fibre orientation θ = 90 °, the modelled fibre fracture criterion is the local exceed of the compressive strength due to bending deformation. After a first crack initiation at initial tool-fibre contact, further potential cracks due to bending of the now unilaterally supported fibres are taken into account. For fibre orientations in the range of (2) 15 ° ≤ θ ≤ 75 °, a bending beam surrounded by matrix material is modelled on elastic foundation, using minimum potential energy principle (MPEP) and WINKLER’s elastic foundation approach.

Furthermore, spring back effects due to elastic deformation are taken into account. For machining fibres with orientation (1) θ = 0 ° = 180 °, the considered chip formation mechanisms are micro-buckling for axial loading and exceeding shear strength for transverse loading. This research aims to develop an analytical force model for orthogonal machining which considers the influence of fibre orientation, tool geometry and increasing tool wear.

Analytical force models are crucial to optimise tool geometries and process parameters for efficient machining of CFRP with various fibre orientations. The material causes distinctive tool wear, which results in a significant increase of process forces. Machining of carbon fibre reinforced polymer (CFRP) still represents a significant challenge due to its anisotropic material structure and brittle fracture behaviour.