DRILLING OF BIOCOMPOSITE MATERIALS: MODELLING AND EXPERIMENTAL VALIDATION

Abstract Induced damage during biocomposites drilling is significantly different to that produced on composites based on synthetic reinforcement such as carbon or glass fibers. In composites reinforced with carbon or glass fibers, induced damage increases with feed rate, however damage was observed to decrease with feed rate in biocomposites reinforced with natural fibers. This work is focused on the explanation of this differences between biocomposites and traditional composites based on the effect of strain rate on the material behavior during machining. A FEM model has been developed in ABAQUS/Explicit to verify this hypothesis. This numerical model has been used to explain the differences found between traditional composites and biocomposites in the influence of the main drilling parameters on induced damage during drilling. Experimental tests were conducted to validate the model through the comparison between thrust forces and damage factor for two different drills geometries on Flax/PLA bio composites. The results indicate that the decrease of induced damage with feed rate is only predicted when the constitutive model accounts for experimental behavior observed in this type of composites. Additionally, the numerical model demonstrated the ability to reproduce the effect of the different cutting conditions (cutting speed, feed, thickness and drill geometry) observed during experimental tests on induced damage during drilling.