One of our PhD students, Dr. Yiwen Gu has successfully completed his PhD, supervised by Prof. Gangadhara Prusty and Prof. Jun Wang.

Title of PhD: A Study of the Abrasive Waterjet Machining Process for Carbon Fibre-Reinforced Polymers

Abrasive waterjet (AWJ) machining has proved to be a promising technology in the machining of carbon fibre-reinforced polymers (CFRPs) without causing thermal damage or excessive machining force. However, the material damage induced by the AWJ machining process in the form of delamination remains a challenge in the hole making process. This study provides a deeper understanding of AWJ cutting and hole making processes for CFRPs of various thicknesses and the correlation between operating parameters and machining performance. A new computational model based on finite element method (FEM) and smooth particle hydrodynamic (SPH) has been developed and verified for the interactions between a waterjet and CFRPs, which can capture large deformations of the waterjet as well as the material removal and delamination of CFRPs.

The results have shown that pop-up delamination is initiated by the material’s elastic response to the release of shock pressures and the traverse shear stress induced by the large bending deformation of material top layers. The hydro wedging effect due to the diverged waterjet further propagates the delamination. The effects of water pressure and stacking sequence on delamination characteristics and size have been identified. Based on the understandings, practical solutions have been proposed to minimise material delamination in AWJ machining of CFRPs. A masking technique has been experimentally verified as being able to eliminate both pop-up and push-out delamination. Along with the selection of appropriate process parameters, the technique will enable damage-free machining of CFRPs by an AWJ.