Time Domain Reflectometry has been applied to detect damage on sandwich structure. Face plated need to be copper plated to embed sensor on surface. Core also needs to be conductive to send signal back. Total 6 lines of sensor were tested with varying impact energy and impact location. TDR were able to locate damage with high accuracy. Damage degrees were detectable for critical hit, but not clear enough to predict impact energy. However TDR was sensitive enough to detect damage that wasn’t visible by visual inspection.