This paper reports the development of health monitoring sensors based on single glass fibers (GFs) coated with single-walled carbon nanotubes (SWCNT)/-epoxy nanocomposites. Uniform coatings with different SWCNT concentrations are successfully produced by a dip coating method, and the coated single fibers are embedded in a dog-bone shaped epoxy model composite. The relationship between the shift of G’ band in Raman spectra and the incremental changes in electrical resistance of the coating when the composite sample is subjected to tensile loads are investigated to establish the sensory function of the coated GFs. The strain sensitive Raman spectroscopy on CNT coated GFs allows an accurate evaluation of the stress distributions along the GF/coating interface....[ Read more ]

This paper reports the development of health monitoring sensors based on single glass fibers (GFs) coated with single-walled carbon nanotubes (SWCNT)/-epoxy nanocomposites. Uniform coatings with different SWCNT concentrations are successfully produced by a dip coating method, and the coated single fibers are embedded in a dog-bone shaped epoxy model composite. The relationship between the shift of G’ band in Raman spectra and the incremental changes in electrical resistance of the coating when the composite sample is subjected to tensile loads are investigated to establish the sensory function of the coated GFs. The strain sensitive Raman spectroscopy on CNT coated GFs allows an accurate evaluation of the stress distributions along the GF/coating interface.

It is found that the samples with a higher SWCNT content broke into fragments while no fragmentation was observed for the sample with a lower SWCNT content when the same level of strain is applied. This observation is a reflection of the higher interfacial shear strength of the coating with a higher SWCNT content. There is a linear relationship between the change in electrical resistance and fiber strain due to the modification of conductive networks. The above findings clearly demonstrate that the SWCNT coated GFs can serve as a strain sensor to monitor the deformation and damage to composite structures.