HAZ behavior of CFRP under quasi-continuous wave laser irradiation governed by anisotropic heat conduction

Carbon fiber reinforced plastic (CFRP) exhibits strong directional thermal responses due to the anisotropy of its carbon fiber-polymer matrix architecture, leading to nonuniform and orientation-dependent heat-affected zones (HAZ) during millimeter-scale quasi-continuous wave (QCW) laser processing. In this work, a multiscale modeling framework is established to link the thermal behavior from individual fibers to fiber bundles and woven laminates. A heterogeneous multiphase anisotropic heat-transfer model is developed to account for the distinct thermal properties, phase transitions, and interfacial interactions of carbon fibers and the polymer matrix. Laser experiments and transient finite-element simulations show good agreement, with an average relative error of 11.91% for HAZ area prediction. An Elliptical Superposition Reconstruction of the Heat-Affected Zone method is further introduced to quantitatively characterize HAZ morphology across different weave types, achieving an area fitting error of 10.92%. Results show that striated structures generate a single elongated elliptical HAZ aligned with the fiber direction, whereas tabby and twill structures form multiple overlapping elliptical segments associated with more complex thermal spreading paths. The strong dependence of HAZ size and morphology on laser incidence location and woven architecture highlights the necessity of structure-specific thermal modeling for improving CFRP machining quality.