Characterisation Methods for Carbon Fibre Reinforced Polymer Composites: Manufacturing, Experimental Testing and Analysis

Sammanfattning

The increasing use of carbon fibre reinforced polymer (CFRP) composites in high-performance applications require reliable methods for quality assessment and defect characterisation. Fibre volume fraction and void content are key parameters influencing the mechanical performance of CFRP composites, however their accurate determination can be challenging due to methodological limitations. This study performs a comparative analysis of different characterisation methods, including matrix digestion, matrix burn-off, optical microscopy, and X-ray computed tomography. The parameters of interest in this work include fibre volume fraction, void content, and additional characteristics such as void morphology, and fibre orientation. Multiple CFRP composite samples are manufactured using the same material system and under the same conditions to enable direct comparison between the methods. The major part of this study focuses on analysing which characterisation method provides the most reliable estimates of the average fibre volume fraction and void content under the considered conditions, as well as understanding how the experimental setup and assumptions affect the reliability and practicality of each method. Furthermore, it aims to identify the strengths and limitations of each method in order to support the development of more informed and consistent characterisation pipelines in the industry, where use of multiple methods is often required in order to have a comprehensive overview of the technology, product or component that is being developed. Overall, this study shows that no single method can fully characterise CFRP composites on its own. Instead, a different approach is needed, where the evaluation of CFRP composites is guided by the application, specific required information, as well as available resources like equipment and time.