<p>For the process optimization when machining composite materials by abrasive water jet (AWJ), it is crucial to understand the formation of the kerf profile and its geometric characteristics. Yet experimental methods cannot fully capture the dynamic evolution of the kerf during cutting, because of the complex, high-speed nature of the process. In this context, the present study provides a numerical investigation of kerf formation in the AWJ cut of glass fiber reinforced polymer (GFRP) composite laminates using a coupled SPH-DEM-FEM approach. This advanced methodology enables a detailed resolution of the complex interactions between high-velocity water, abrasive particles and the anisotropic composite material. The present research systematically elucidates the mechanism of kerf angle formation, demonstrating how progressive erosion and material removal vary across the thickness of the laminate. The effects of standoff distance and traverse speed on the kerf angle are also explored. In addition, the stress distribution within the GFRP composite during AWJ cutting is investigated, revealing highly localized stresses at the jet entrance and amplified stress concentrations in the final layers, which are susceptible to damage. The results of the present numerical model contribute significantly to a deeper theoretical understanding of AWJ cutting mechanics in composite materials, offering valuable guidance for process optimization to improve cut quality and minimize manufacturing defects in high-performance GFRP components.</p> Graphical abstract <p>SPH-DEM-FEM simulation of kerf formation and stress distribution during abrasive water jet cutting of GFRP composites</p> <p></p>