DAMAGE PROPAGATION AND THERMOGRAPHY IN DISCONTINUOUS CARBON FIBER COMPOSITE (DCFC) UNDER TENSILE (FATIGUE) LOADING

Abstract

The discontinuous carbon fiber composite (DCFC) has a different damage behaviour due to non homogenuous sub structure. Consequently, monitoring and diagnosis of DCFC damage mechanisms require the application of a contactless method in real-time operation, i.e., non destructive method of thermography. The aim of this study is to investigate the damage propagation of DCFC material under tensile (fatigue) condition with non destructive testing (NDT) thermography method. Under fatigue testing, temperature evolutions were monitored by an Infra-Red (IR) camera. The results show that damage propagation and thermal response indicated the similar behaviour which consists of three stages. At the beginning, low temperature increased until ≈ 10% of fatigue life due to the initial damage. The initial damage propagated and the temperature reached the stable thermal state due to the saturation in the damage appearance of micro cracking of matrix and chip until ≈ 80% of fatigue life. At the last ≈ 20% of fatigue life, damage continued to propagate and provoked the occurrence of macro damage that induced the final failure indicated by highest peak of temperature. The analysis from the experiment results concluded that thermal response relates with the damage propagation of DCFC under fatigue loading.