Getting Information on Impact Damage of Carbon Fibre-Reinforced Composites from Thermal Signature Evolution

The susceptibility of carbon fibre-reinforced polymers to impact damage is a well-known problem and drives efforts of researchers towards the creation of new materials, which may be able to contrast impact. Being difficult to predict the behaviour of a newly conceived material during the design phase, specific tests are necessary to assess its impact resistance. This is generally obtained through lengthy tests, which, amongst others, are aimed to find a relationship between the impact energy and the size of the produced damage. A fast and relatively cheap way appears to be in-line monitoring of impacts with an infrared imaging device; the obtained information can contribute to enhance the knowledge of impact damage mechanisms. The attention of this paper is mostly focused on post-processing and analysis of thermal images, which were recorded during in-line monitoring of impact tests. The obtained results are compared with the existing literature and a general agreement is found. As important points, from mechanical-coupled thermal effects, it is possible to get information about some characteristic times such as the impact duration and the time at which peak contact force occurs as well as to individuate damage initiation. These findings can be achieved in a remote way, without any contact with the part under investigation and without any interference with the test execution.