S, Gurucharan and M, Ramji
(2018)
Progressive damage analysis of CFRP Laminate
with circular cutouts under flexural loading.
Masters thesis, Indian Institute of Technology Hyderabad.
Abstract
Application of a flexural or bending load on a Carbon fiber reinforced polymer(CFRP) specimen
leads to both tensile and compressive stress state across the thickness of the specimen thereby resulting
in a more complex damage behavior as the tensile and compressive failure modes of a composite
material are different. Study of damage behavior of specimen includes location of damage initiation,
damage propagation, various types damage modes and their interactions, prediction of damage
initiation load and final failure load. Damage behavior of the CFRP specimen has to be studied
for its efficient and sustainable design. In the present thesis, damage behavior of pristine CFRP
specimen (without hole), specimen with both single circular hole and multiple circular holes having
three different configurations (two hole longitudinal (2HL), two hole transverse (2HT) and two hole
diagonal (2HD)) was studied both experimentally and numerically under four point flexural loading.
The layup sequence of the CFRP specimen having Unidirectional (UD) [0]16 and Quasi-isotropic
[−45/0/45/90]2s are studied. Two-dimensional Digital Image correlation(DIC) technique was employed
for capturing the in-plane displacement and strains across the thickness of the specimen.
Finite element (FE) based Progressive damage analysis(PDA) the CFRP specimen was performed.
In the progressive damage model, Hashin’s failure criteria was implemented for the prediction
of damage initiation of both fiber or matrix at a lamina level, material property degradation
model was implemented for modelling damage evolution in the specimen and cohesive zone model
was implemented for predicting the intiation and propagation of interlaminar delamination between
layers of the specimen. Damage behavior of the specimen obtained from experiment was compared
with the results obtained from PDM for validation. Additionally, the variation of load vs displacement,
longitudinal strain distribution over the thickness face of the CFRP specimen obtained both
experimentally and numerically were studied and the corresponding plots obtained from both were
compared.Finally, the load carrying capacity of pristine specimen, specimen with single hole and
specimen with multiple holes with three different configurations (2HL,2HT and 2HD) were compared
and it was also seen which type of specimen according to the two lay up sequences which are
unidirectional [0]16 and Quasi [−45/0/45/90]2s was more stiffer and stronger
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