A physics based multi-scale framework for surface evolution in abrasive waterjet textured additively manufactured continuous carbon fiber thermoplastic composites

Continuous fiber reinforced thermoplastic composites fabricated by additive manufacturing (AM) show strong potential in composite repair applications, particularly for restoring complex geometries while maintaining parent-patch continuity. In composite repair, the performance of the adhesive joint is critically dependent on the surface integrity of both the parent structure and the repair patch. Abrasive waterjet (AWJ) texturing provides a controllable and environmentally friendly method for surface preparation. Existing studies, which are largely empirical, relate process parameters such as waterjet pressure and traverse speed to surface metrics, with limited insight into the governing mechanisms. This study proposes a physics-based, multi-scale framework to interpret surface evolution during AWJ machining of AM-fabricated composites. At the macro-scale, waterjet pressure and traverse speed govern AWJ’s impact energy and exposure time, determining the effective energy input to the surface. At the micro-scale, the erosion response is influenced by fiber orientation, impact angle, and matrix plasticity, leading to a combination of brittle and ductile material removal mechanisms. The interaction of these local erosion mechanisms generates the meso-scale surface topography, characterized by parameters such as crater volume (~0.6 to ~8 mm³/cm²) and arithmetic mean height (~15 to ~130 µm), exhibiting a non-linear relationship between AWJ input parameters and resulting surface metrics. By linking process physics, material response, and surface characteristics, the study enables predictive control of surface quality without extensive experimentation. This work supports the development of repair-oriented manufacturing framework aimed at extending the service life of high-value thermoplastic composite structures, in line with circular manufacturing practices.