Composites are ever more widely employed in many industrial sectors: transport (aerospace, automotive and naval), energy, medical, alimentary, etc. The important aspect is to use the most adequate type of composite for the specific application. The attention of this work was devised towards two types of composites: thermoset and thermoplastic matrix based composites. Composites based on a thermoplastic matrix seems to possess good energy impact performance compared to their thermosets matrix counterparts, which are more vulnerable to low energy impact. However, it is still necessary to investigate impact damages of composite materials as they behave in a quite complex way, still not completely understood.
When using an infrared camera to monitor impact events, by simply analyzing the temperature signatures arising during impact, it has been learned that it is possible to recognize type of damage, cracks in matrix, delamination and influence of manufacturing defects. Indeed, by using modern infrared thermography technologies, it is possible to follow the evolution in time and in space of thermo-elastic and -plastic phenomena arising during impact of different types of composites which may involve change of either matrix, or reinforcement.
Italian researchers from University of Naples Federico II, CRdC Tecnologie and National Research Council used infrared thermography to investigate impact damaging of composite materials involving both a thermoset matrix and a thermoplastic one, reinforced with either carbon or glass fibers. The authors then analyzed the recorded thermal images in both qualitative and quantitative ways. Results of this research were published in the peer-reviewed journal, Composite Structures.
The thermoset matrix used in this investigation is broadly epoxy resin, while thermoplastic matrix is either a pure polypropylene, or a modified one with 2% addition of a coupling agent. Woven and unidirectional carbon fibers were used as reinforcement for epoxy resin while, to allow for direct comparison, weave woven glass fabric was used as reinforcement for both epoxy resin, or pure and compatibilized polypropylene.
Impact tests were carried out with a modified Charpy pendulum allowing enough room for positioning of the infrared camera to view the side opposite to that struck by the hammer.
A wealth of information can be derived from thermal images, including determining the time interval the impactor remains in contact with the specimen surface. Moreover, information on bending and deformation of the surface under the impactor pushing force can also be obtained. The outcome of this research will assist in improved characterization of impact damaging of composite materials.
This study demonstrates that monitoring and analyzing thermal signatures arising at impact supplies information useful for material characterization, specifically for identifying initiation and propagation of the impact damage.
Meola1, S. Boccardi1, N.D. Boffa1, F. Ricci1, G. Simeoli2, P. Russo3, G.M. Carlomagno1. New perspectives on impact damaging of thermoset- and thermoplastic-matrix composites from thermographic images, Composite Structures 152 (2016) 746-754.Show Affiliations
- Department of Industrial Engineering – Aerospace Division, University of Naples Federico II, Via Claudio, 21, 80125 Napoli, Italy.
- CRdC Tecnologie s.c.r.l., Naples, Italy.
- Institute for Polymers, Composites and Biomaterials, National Council of Research, Pozzuoli (Na), Italy.
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