Low-velocity impact damage detection and characterization in composite sandwich panels using infrared thermography

This paper presents an experimental investigation into the impact damage detection of Paulownia wood core sandwich structures. The structures were impacted by a hemispherical-nosed head with a of diameter 16 mm at impact energies ranging from 22 to 77 J, and infrared thermography (IRT) was used to characterize the impact damage types and extents of the impacted specimens. The test results showed that it is possible to acquire damage information from the temperature distribution images acquired by IRT. Matrix cracking, delamination and fiber breakage damage were effectively characterized by a continuous dark region with a straight shape, a continuous white hot spot in the impact region and a continuous dark spot perpendicular to the fiber direction, respectively. Infrared detection can be used to detect subsurface defects and damage. The effects of different impact energy levels, fiber thicknesses and fiber stacking sequences on the damage induced in the structures were also discussed.