Very little experimental work has been done on the transverse elastic properties. I would like to know if there is any references to Transverse Poisson's ratio and Transverse modulus of carbon fiber. I would like to input these properties into my FEA for determining the properties of a carbon/epoxy composite.
There are different values reported for transverse elastic modulus of carbon fibers ranging in 10-30 GPa. I have found for AS4 carbon fibers in the following article that E2 = 13 GPa, nu12 = 0.3, and nu23 = 0.46.
http://dx.doi.org/10.1016/j.compscitech.2015.02.008
Dear colleagues, is the difference between values of longitudional and transverse modulus of fiber causes the essential influence on strength analysis of composites by FEA? The fibers as reinforcing components of composite are working on tension mode generally. But any case the question of Ganesh Venkatesan is interesting and I would like to know the results of comparison of corresponding analysis. Best regards
Dear Serge,
The longitudinal modulus of carbon fibers is about 200-300 GPa (~20 times larger than the transverse modulus). This brings about much higher elastic properties for carbon-fiber-reinforced plastics in the longitudinal direction. With regard to non-linear properties, the continuity of carbon fibers in the longitudinal direction and their high modulus causes a high longitudinal strength. However, in the transverse direction, the stress concentrations, caused by the modulus mismatch between fiber and matrix, reduce the strength. Therefore, carbon fibers increase the longitudinal strength of the matrix, but degrade its transverse strength. That is why the composite strength properties in longitudinal and transverse directions are dissimilar.
The strain concentrations between neighboring glass fibers is observed at the micro-scale in real experiment and validated with FEA results in a previous study of us:
Article Full-field strain measurements at the micro-scale in fiber-r...
Hi Serge and Mahoor,
Thanks for the reply, I agree on the aspect that the elastic properties of carbon fibers are transversely isotropic (i.e the longitudinal young's modulus and transverse young's modulus are not the same). Glass fibers are isotropic, i.e the elastic properties are same in all directions. From a processing perspective, my understanding is that, PAN carbon fibers have randomly oriented planes, that is why they are transversely isotropic.
I wish I saw Mahoor's answer earlier, however, I backed out the fiber properties from the experimental data of the composite, using FEA. The reason as to why I am not using data from other papers is that they also back out from some composite experimental data, but neglecting the void content in the composite.
Some literature that I could find on AS4 carbon fibers specifically are, Sun and Vaidya (1996), Daniel and Ishai (2006), King et al. (1992), Gipple and Hoyns (1994), Cairns and Adams (1981) and Grimes et al. (1980). But they neglect the void content in the analysis. Moreover, it is practically impossible to measure the fiber transverse elastic properties.
Thanks,
GV
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