Applied Sciences (Switzerland), cilt.16, sa.6, 2026 (SCI-Expanded, Scopus)
Low-velocity impacts during manufacturing and maintenance (e.g., tool drops) can induce barely visible impact damage in composite aircraft structures, motivating sensing-assisted approaches for rapid post-event assessment. This study proposes and validates a strain-based structural health monitoring framework for carbon-fiber-reinforced polymer (CFRP) panels by combining surface-mounted strain gauges with explicit finite element analysis (FEA). Drop-weight tests were con-ducted in accordance with ASTM D7136 using a 1.0 kg hemispherical impactor at drop heights of 250–400 mm. Three strain gauges were positioned at 1.25 mm, 32.5 mm, and 52.5 mm from the impact point to quantify the spatial attenuation of peak surface strain. The measured peak strains exhibited clear-dependent decay and increased with impact energy up to 350 mm, whereas the 400 mm case showed a non-monotonic response and a pronounced deviation from an elastic energy-scaling baseline, consistent with a transition to damage-dominated energy dissipation. Dedicated MSC Apex/Nastran Implicit simulations reproduced experimental trends and provided a physics-based digital twin for interpreting strain signatures in elastic regions, correlating them with likely damage states.