Effects of laser processing parameters and scanning angle on damage morphology and residual tensile properties of CFRP laminates with a continuum damage mechanics model

Laser processing of carbon fiber-reinforced polymer (CFRP) composites offers significant advantages in precision and efficiency, yet the thermal damage it induces remains a critical concern for structural integrity. This study investigates the effects of laser drilling and cutting on the damage morphology and residual tensile properties of T300-3K/epoxy CFRP laminates, with systematic variation of laser power, irradiation duration, scanning angle, and scanning distance across 21 processing conditions. White-light interferometric microscopy characterized three-dimensional ablation topography, and uniaxial tensile testing quantified mechanical degradation. For drilled specimens, increasing power from 250 W to 1000 W enlarged the ablation crater diameter by approximately 200% (1007-3021 μm), while extending irradiation duration from 0.5 s to 1.0 s produced a further 37% increase. For cut specimens, perpendicular scanning induced a broader heat-affected zone and more severe interfacial disruption than fiber-parallel scanning due to anisotropic thermal conductivity, with the maximum surface height difference reaching 4259 μm at 500 W and 90°. Residual tensile strength decreased monotonically with increasing energy input: drilled specimen strength declined from 735 MPa to 293 MPa (a reduction of over 60% to the pristine strength of 954 MPa); cut specimen strength at 500 W decreased from 466 MPa at 0° to 233 MPa at 90° due to progressive fiber severance, with cut specimens consistently weaker than drilled counterparts owing to kerf-induced stress concentration. A CDM-based empirical model integrating all four parameters was developed; nonlinear regression yielded A = 0.0266187, m = 0.464431, n = 0.645373, α = 0.0745099, β = 0.22664, and R2 = 0.9151, providing a validated quantitative tool for structural integrity assessment of laser-processed CFRP components.