Methods for Degradation Assessment of Fibre Reinforced Polymer Structure Exposed to the Simultaneous Influence of Temperature and Humidity

Abstract

Fibre reinforced polymers are commonly used in many industrial branches. The continuous technical progress in the applied science and technology requires more and more advanced materials. The structural damage can occur due to many factors which are difficult to predict in advance. Safety and reliability requirements results in development of a variety of structural health monitoring (SHM) systems and non-destructive testing (NDT) techniques. In the paper the comparative studies of two non-destructive testing (NDT) methods (infrared thermography and THz spectroscopy) are presented. NDT techniques that can be applied for evaluation of internal structure of composite materials are infrared thermography (pulse and/ or vibrothermography) and THz spectroscopy. Both methods can be used for identification of material structural disintegrations. Infrared thermography allows to observe changes of temperature field distribution, while THz spectroscopy allows to observe changes of absorption coefficient, refractive index or scattering of THz waves propagating throughout analysed material. The goal of the paper is to study the sensitivity and applicability limitations of proposed methods with application to fibre reinforced polymers under simultaneous temperature (form negative to elevate) and relative humidity influence.