Finite element modelling of overlapping abrasive waterjet milled footprints

Abstract

Successful automatic simulation of the resulting surface obtained by abrasive waterjet (AWJ) milling is dependent on the ability to model the overlapped jet footprints. In this article an attempt has been made to develop a finite element (FE) model to simulate the overlapping AWJ milled footprints over a range of step-over distances, water pressures and traverse speeds at 90° jet impingement angle. A methodology has been proposed by which multiple overlapped AWJ milling passes can be simulated without being computationally extremely expensive. The FE results are validated by comparing the simulated footprints and erosion rates with the corresponding experimental data. The workpiece material is modeled as Ti6Al4V, an extensively used material in the aerospace industry, and the abrasive particles are modeled as garnet which is a commonly used abrasive during AWJ machining. The model provides the opportunity to study and improve the mass distribution of the abrasive particles around the jet central axis. The simulated footprints and erosion rates obtained when overlapping the jet footprints are shown to be in good agreement (with maximum errors under 15%) with the experimental data. The results of this research are quite encouraging while taking into account the possible sources of errors within the experimental data (e.g. non-constant pressure, particles sizes and fragmentation).