Prediction of surface roughness in abrasive waterjet trimming of fiber reinforced polymer composites

Surface roughness is a valuable metric when assessing abrasive waterjet machining (AWJM) cut quality. This paper presents 2D and 3D models capable of predicting the surface roughness during abrasive waterjet (AWJ) trimming of composite substrates. The composites used were a carbon-fiber laminate with an epoxy resin and a random oriented carbon-fiber/vinyl ester. The models were based on an earlier rigid-plastic erosive particle indentation model capable of predicting crater sizes using the particle impact and substrate properties. In the 2D model, single particle impact craters were aligned to form multi-particle impact profiles that were iteratively superimposed until a steady-state surface roughness was achieved. The 3D model generated conical craters that were individually superimposed until a steady-state surface roughness was achieved. The models were capable of predicting the surface roughness with an average error of 10% and 16%, for the 2D and 3D models, respectively. The models show that the surface roughness decreased with an increase in particle velocity, a decrease in kerf taper, and an increase in the dynamic hardness of the target.