Self-Heating Based Vibrothermography - a Non-Destructive Testing Method for Polymeric Composite Structures

Non-destructive testing of polymer matrix composite structures is a key part of their proper operation in many industries, primarily in aircraft, aerospace and automotive ones, where they occur most often. Among a variety of methods, infrared thermography is one of the fastest testing methods, and thus, successfully applied for inspection of composite structures. However, application of active thermography for non-destructive testing usually needs external heat sources, which makes this approach inefficient when such the type of heating is not possible or if the direct access to the tested structure is limited. In this paper, the authors present a novel method of thermographic testing of polymer matrix composite structures using the self-heating effect. Due to the viscoelastic nature of a polymeric matrix, it dissipates mechanical energy in a form of heating under vibrations. Following this, by exciting mechanical vibrations with a special multi-harmonic signal it is possible to excite heating in the tested structure on its entire surface, and observe the thermal response using infrared camera. Based on such an observation the detection and identification of manufacturing defects and damage are possible. The demonstration of capabilities of damage detection using this method is shown and discussed.