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M. Rodríguez-Hortalá, D. Salaberger:
"Jahresbericht DEFCOM - The effect of DEFects in structural COMposites";
Report for Firma SECAR Technologie; Report No. 5, 2012; 28 pages.

Polymer based composite materials are very unique materials, and it is quite difficult to give some general assessment of their structure and properties.
The investigated samples are unidirectional reinforced carbon fibre reinforced polymers(CFRP) made by pultrusion.
Motivation: to try to assess composite microstructure and to estimate its thermal and mechanical properties. These are very important for predicting the material performance.
The influence of curing degree on all main properties was also studied. Because it is well known that the increasing of a curing degree increases the glass transition temperature, this at
the same time increases the stiffness and therefore decreases the plasticity and other mechanical properties. The type and extent of this dependence is necessary to know to control the quality of the material during its use.
A failure analysis was made after mechanical testing to identify failure mechanisms and to understand them in order to estimate the defectiveness of CFRP made by pultrusion process with its own features.
3D X-ray tomography was performed in order to determine defects three dimensionally. Some specimens were scanned before and after mechanical testing.
Scans for defect characterisation were performed at limited resolution so far to be able to find defects in a bigger volume of the specimens. In addition to that scans with higher resolution
were performed to be able to detect small pores or other defects.
For specimens made by the Spanish project partner IMDEA that were produced by a hot press procedure, pores were characterized quantitatively.

CFRP, Characterisation, Computed Tomography, Mechanical testing