Abstract:
Structural Health Monitoring (SHM) of composite materials is a challenging task due
to their heterogeneous structure and complex failure behavior. Traditional methods
for SHM have certain limitations, such as localized measurement, computational processing costs, sensitivity to environmental factors, and the need for high-resolution
cameras. Recently, materials like carbon nanotubes (CNTs) and graphene, known for
their excellent electrical and mechanical properties, have opened new research avenues
for SHM sensors development. However, current research largely focuses on costly
experiments. Finite element modeling (FEM) of SHM systems using these emerging
materials is not yet widely explored. This study presents a novel approach to modeling the electrical response of sensors embedded in fiber-reinforced polymer composites
using FEM at the macro scale. Initially, validation studies were conducted using the
Abaqus simulation tool, where a graphene sheet is coated on a glass fiber reinforced
polymer (GFRP) composite. Simulations are carried out for loadings at strain rates
of 0.2 mm/min, 2 mm/min, and 20 mm/min. The mechanical behavior of GFRP is
assumed to be elastic-plastic, and the electrical response, coupled with the mechanical response through the strain of the graphene sheet, is obtained using the UVARM
subroutine. Root mean squared error (RMSE) of 3.574, 0.889, and 1.315 in fractional
change in resistance (FCR) for 0.2 mm/min, 02 mm/min, and 20 mm/min, respectively,
which is significantly small, demonstrating a good correlation between the simulations
XII
and experiments. The study is further extended to embed the graphene sensor in unidirectional GFRP with different fiber orientations. The electro-mechanical responses
are plotted for each system of graphene-coated laminates with different fiber orientations, providing deep insight into monitoring deformation in unidirectional GFRP
composites. The FCR at damage is 29%, 15%, and 30% for graphene-coated GFRP
laminates with fiber oriented at [0◦
]4s, [90◦
]4s, and [0◦
, 45◦
, −45◦
, 90◦
]s, respectively.
This study provides a direction for future microscale FEM modeling of piezoresistivity
in graphene-coated composite laminates.
