IR Thermography methods on nondestructive testing of ballistic covers made of multi - layer carbon fiber

Presently a lot of designs of light armours are based mainly on the multilayer composite materials. Thanks to these materials it was possible to achieve highest levels of ballistic resistance of specific armour at limited weight. The weight (area density) and the performance have direct influence on the value of combat ability of equipment and soldiers. Carbon fibers are basic types of reinforcement used in composites. They have many technical applications including light ballistic covers where they are mostly used as multi-layer composite materials constituting a structure made of several interconnected layers or many layers of carbon fibers, or in combination with other materials. Light ballistic covers have usually thickness of several to 10-20 mm and potential defects occurring in them have thermo-physical properties definitely different than materials they are made of so the non-destructive tests using thermography methods may be effective in detecting these defects. The main methods of active thermographic tests are as follows [1, 2]: - Pulsed Thermography – PT, - Step Heating Thermography – SHT, - Lock-in Thermography – LT, - Vibrothermography – VT. In the paper an application of Step Heating Thermography and Vibrothermography to detection of delaminating area of CFRP composites after mechanical impacts is presented.