Non-destructive testing of fiber-reinforced composites by terahertz method

Fiber-reinforced composites are materials that are increasingly replacing metals in many construction solutions. Damage to the composite structure may occur both as a result of technological errors in the production phase and during operation as material fatigue or as a result of an impact by a foreign body. The specificity of defects that occur in fiberreinforced composites results in the development of non-destructive testing methods that enable the detection of these defects. One of these methods is the use of terahertz radiation. Terahertz radiation penetrates well through non-metallic materials. It can therefore be used for non-destructive testing, especially of composites reinforced with glass and aramid fibers. The terahertz band has been known for many years, but interest in the use of terahertz radiation in non-destructive testing has only recently emerged. This is due, among others, to the availability of sources of terahertz radiation of appropriate power enabling these tests. The radiation source is an important element of nondestructive testing with active methods that are most often used in this type of testing. In non-destructive testing, the terahertz radiation range from 100 GHz to 300 GHz is most often used. In this paper we present the results obtained using the transmission terahertz method.