R. KARTHIKEYAN, S. RAJKUMAR: INVESTIGATION OF THE EFFECT OF INCONEL PARTICULATE FILLER ...
653–659
INVESTIGATION OF THE EFFECT OF INCONEL PARTICULATE
FILLER ON THE MECHANICAL AND FIRE-RETARDANT
CHARACTERISTICS OF GFRP COMPOSITES
RAZISKAVA VPLIVA DODATKA POLNILA NA OSNOVI DELCEV
IZ INCONELA NA MEHANSKE IN OGNJEVARNE LASTNOSTI
GFRP KOMPOZITOV
Ravikumar Karthikeyan, Subbiah Rajkumar
*
Central Institute of Petrochemicals Engineering and Technology: School for Advanced Research in Petrochemicals, Chennai, India
Prejem rokopisa – received: 2022-07-12; sprejem za objavo – accepted for publication: 2022-10-10
doi:10.17222/mit.2022.559
This paper reports the effect of incorporating Inconel particles as filler for enhancing the delamination and mechanical strength
of glass-fiber-reinforced epoxy composites. It is intended for application in renewable energy. Glass fiber plays a vital role in re-
newable-energy industries for its non-corrosiveness and lower maintenance cost. The mechanical properties of glass fibers make
the renewable industry for effective utilization in the manufacturing of turbine blades in onshore and offshore environments, as
well as the addition of fillers enhances the mechanical properties of the material. This study comprises validating three different
compositions of Inconel blended with epoxy resin for the preparation of laminates using a vacuum-infusion process. The tensile
and flexural properties of the composites were experimentally examined and validated for the enhanced use of structural appli-
cations in the field of renewable energy. In addition to the mechanical characterization, a finite-element validation was used to
determine the delamination effect. The Ansys Composite PrePost (ACP) module was used to validate the Inconel-blended com-
posite materials. The flammability characteristics were determined as per the UL-94 standard for both vertical and horizontal
flame tests. The water-absorption characteristics were also estimated for the three different proportions of the Inconel-filled
laminates. The study reveals that the incorporation of Inconel powder enhanced the mechanical properties, contact angle and the
fire-retardant characteristics of the glass-fiber epoxy-blended laminates.
Keywords: delamination, Inconel, flammability, mechanical properties
V ~lanku je opisan vpliv dodatka delcev Ni superzlitine Inconel k, s steklenimi vlakni, oja~anemu epoksidnemu kompozitu
(GFRP; angl.: Glass Fibers Reinforced Particle epoxy composite). Namen dodatka je bil izbolj{anje odpornosti kompozita proti
cepljenju in pove~anje njegove mehanske trdnosti. Steklena vlakna imajo mo~no vlogo v industriji naprav za obnovljivo
energijo (npr. lopatice v vetrnih elektrarnah) zaradi dobrih antikorozijskih lastnosti in majhnih stro{kov vzdr`evanja. Mehanske
lastnosti pletiv iz steklenih vlaken v komponentah za obnovljivo energijo omogo~ajo izbolj{anje u~inkovitosti turbinskih lopatic
v vseh okoljih (morje, kopno), ki pa se z dodatnimi polnili kompozitnega materiala {e izbolj{ajo. V {tudiji so ocenjevali lastnosti
laminatov izdelanih z vakuumskim nalivalnim postopkom. Pri tem so uporabili tri razli~ne sestave oziroma me{anice epoksi
smole z delci Inconela nalite na pletivo iz steklenih vlaken. Eksperimentalno so dolo~ili natezno in upogibno trdnost
kompozitov in jih ocenili za izbrane konstrukcijske oziroma funkcionalne elemente, uporabne na podro~ju obnovljive energije.
Poleg mehanskih lastnosti so ocenili {e delaminacijo s pomo~jo metode kon~nih elementov. Uporabili so programsko orodje
Ansys z modulom Composite PrePost (ACP). V`igalne lastnosti izdelanih laminatov so dolo~ili po standardu UL-94 za obe
smeri, z vertikalnim in horizontalnim preizkusom. Ocenili so tudi absorpcijo vode (kontaktni kot) v laminatih s tremi razli~nimi
vsebnostmi polnila oziroma delcev Inconela. Ugotovili so, da dodatek delcev prahu iz Inconela izbolj{a mehanske lastnosti,
pove~a kot omakanja in odpornost proti v`igu izdelanih kompozitov iz epoksi laminatov oja~anih s steklenimi vlakni.
Klju~ne besede: delaminacija, Inconel, vnetljivost, mehanske lastnosti
1 INTRODUCTION
In recent years the delamination of composite materi-
als has become a serious issue in many industrial sectors.
Composite structures have been designed for a specific
requirement and it has been made suitable for use in dif-
ferent environmental conditions. The delamination effect
in composites has been focused as the major cause of the
damage to structures. The delamination occurs when the
inter-laminar stress of the plies exceeds the overall yield
stress of the materials interfaced. Delbariani et al. inves-
tigated the inter-laminar fracture toughness of laminates
based on the critical energy. If the rate of the energy re-
leased on the laminates exceeds the critical energy, then
the chances of the delamination were found to be a maxi-
mum.
1
Dong estimated the effect of process-induced
small voids in fiber-reinforced composites also assumed
to have an increased axial shear modulus and transverse
modulus compared to the large voids. The influence of
the voids in the fiber-reinforced composites influences
the physical properties of the material.
2
Swolfs et al. vali-
dated the flexural behavior of the material, generally the
flexural tests were performed using a three-point bending
apparatus under bending condition, the upper layers will
tend to be in compression mode and the bottom layers in
the tension mode, which causes an inter-laminar shear
Materiali in tehnologije / Materials and technology 56 (2022) 6, 653–659 653
UDK 666.189.21 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 56(6)653(2022)
*Corresponding author's e-mail:
rajkumarcipet1@gmail.com (Subbiah Rajkumar)

and potentially initiates the delamination across the
thickness for determining the delamination strength of
the materials.
3
Fotouhi et al. determined that the majority
of the damage in the composites is due to the fiber ma-
trix de-bonding. He also estimated that mode-1 condi-
tions are found in the unidirectional specimens, com-
pared to the woven fabric specimens. The SEM
examinations also confirmed the above results. Further
he used acoustic emission to determine the delamination
in glass and epoxy-composite materials.
4
Peng et al. discussed the improvement of material
performance by reducing the delamination effect. The
geometrical featuring of the composite materials with
long fibers provides better longitudinal strength and stiff-
ness, whereas the polymer matrix is responsible for the
toughness and delamination strength of the material.
5
Zou et al. focused on the composite planar behavior and
the properties, the thickness of the laminate exhibited
considerably lower material characteristics. The major
failure mode is due to the parting of an initially bonded
single ply, causing the delamination. The machining of
the composites also causes delamination to occur, and
the damage extension criterion was used to determine the
delamination. The damage-extension criterion highlights
the threshold level of the strain rate, thus making it pos-
sible to determine the delamination by altering the cohe-
sive elements attached to the geometrical structure.
6
Hiroakiet et al. used carbon nano-fiber reinforcement in
the interlayer of the composite material for preparing
mode-I specimens with three different amounts of
nano-carbon at the interlayer from 10 g to 20 g the frac-
ture toughness has been improved, but when the amount
of non-carbon increased to 30 g, it decreased the fracture
toughness of the material. This information provides a
valid procedure that a limited addition of reinforcements
only provides a structural improvement.
7
Zhao et al. ex-
perimented on PTFE (poly-tetra-fluoro-ethylene) with
copper, lead and nickel, with 30 % filler content. The ad-
dition of the filler mainly focused on the wear character-
istics of the material, with PTFE as the base. The addi-
tion of the filler content increased the load-bearing
capacity of the materials.
8
Zujin et al. explained that the
delamination in wind turbines was found mostly in the
outer skin, which resulted in catastrophic failure. The
different failures of the delamination happened in the in-
ternal core materials, which were found to be in the stag-
gered shape. Due to the deformation, the direction re-
verses in the condition that the shell of a blade causing it
to deform in the reciprocating direction. The trailing
edge was considered to be one of the instability zone in
the wind turbines due to the large amount of deforma-
tion.
9
Y. J. Liu et al. formulated a FE model for deter-
mining the impact influenced delamination for fiber-re-
inforced plastic materials. The paper mainly valued the
stacking sequence of the laminates; the laminates with
increased adjacent layers showed reduced delamination
area. The impact strength of the material can be in-
creased with the proper orientation of the laminate angle
with an increased layer angle.
10
Wilk demonstrated the
testing methodology for determining the inter-laminar
delamination in laminates. The strain energy release rate
(SERR) has been defined as the energy required to ex-
tend the crack to an infinitesimal length. The mathemati-
cal equation representing the SERR R
is given by Equa-
tion (1).
d
PC
bl
R
d
d
=
⋅
2
2
(1)
where P is the applied force, b is the specimen width,
l is the crack length, and C is the specimen compliance.
The three modes of crack propagation are Mode I (open-
ing), Mode II (sliding shear) and Mode III (tearing
shear).
The cyclic loading conditions were usually described
by the power law relationship between the rate of
delamination growth with fatigue cycles to the maximum
applied SERR, named Paris’ law, and is given by Equa-
tion (2).
d
d
a
N
G =⋅   max
(2)
where da/dN is the delamination growth rate, G
max
is the
maximum SERR in cycle, and  and  are the experi-
mentally obtained parameters.
11
Finite-element analyses
(FEA) were applied for the validation of the structural
capacity of the laminates with different length scales.
As per the FEA, delamination was predominately identi-
fied in the two layers of dissimilar fiber orientation,
causing the fiber to peel out from the matrix and the in-
terfacial cracks were also generated on the surface due
to a reduction in the stiffness of the corresponding inter-
facing layer. Cortes et al. concluded that Inconel 718
grade material had the slowest crack growth rate due to
its high yield stress, which leads to the development of
the plastic zone for avoiding the crack growth.
12
Nikhil
et al. evaluated that the reduction in metallic fillers in
composites diminished the compressive behavior and
improved the impact strength. The key factor for the re-
sults was due to the aspect ratio of the filler used in the
composite material.
13
Pincheria et al. validated that the
interfacial shear strength (IFSS) between the matrix and
the fiber determines the internal ply behavior of the
composite material and the overall inter-laminar
delamination strength of the composites mainly depends
on the fiber-matrix interface.
14
Yang et al. claimed that
the peel strength and the flammability characteristics are
much higher for epoxy-based resins compared to other
phenolic resins.
15
The failure in the composite structures
was mainly due to the delamination effect in the con-
necting zones, the improper filling of the resin and the
resin deficiency in the maximum load concentrated ar-
eas initiates the failure and making the entire structure
collapse due to the effect of cyclic loads. The overall re-
views encapsulate the selection of filler and the propor-
tions for effective utilization of the materials for specific
R. KARTHIKEYAN, S. RAJKUMAR: INVESTIGATION OF THE EFFECT OF INCONEL PARTICULATE FILLER ...
654 Materiali in tehnologije / Materials and technology 56 (2022) 6, 653–659

applications. Inconel 718 grade filler is used for the cur-
rent study with glass fibers and epoxy resin.
2 EXPERIMENTAL PART
The experimental procedure includes the manufactur-
ing of the laminate by a vacuum-infusion process (VIP)
and the mechanical properties of the prepared samples
were tested and evaluated to determine the effect of add-
ing the filler material.
2.1 Materials
Araldite LY 556 resin and the hardener Aradur HY
951 were used for preparing the matrix. The E-glass fi-
ber mat was used as reinforcement for the preparation of
the samples. The materials were purchased from the Go
Green India Pvt limited. As per the supplier, the resin ex-
hibits low viscosity and excellent water resistance. The
materials used for preparing the samples are listed in Ta-
ble 1.
Table 1: Materials used for preparing the samples
Description Material Grade/Composition
Fiber E – glass fiber 300 GSM
Matrix Resin
Resin – Araldite
Hardener – Aradur
AY-556
HY-951
Filler Inconel 718
2.2 Chemical composition of the Inconel 718
The epoxy and the glass fibers were used as the ma-
trix and the fiber for the preparation of the composite
materials. The Inconel 718 filler of three distinct percent-
ages was added, the general chemical composition of the
Inconel filler is shown in the Table 2. The size of the
Inconel particles was 100 μm and it was spherical in
shape.
2.3 Material preparation
The samples were prepared by the VIP shown in Fig-
ure 1. The main scope of the VIP is to absorb the excess
resin in the fiber and to avoid the air traps present during
the fabrication of the mat, thus making the material more
stable with a resistance to crack propagation. The vac-
uum-suction pressure is the key source for the VIP, the
major aspect of the vacuum infusion process is that the
pressure used to drive resin into the laminate for prepara-
tion of the components. Three different percentages of
Inconel powder were segregated into three different
weights for mixing it with the epoxy resin. Initially the
fiber, resin and the hardener were weighed as per the rule
of mixture. The process was conducted as per the proce-
dure. The pump is continuously operated for about
3–4 h, ensuring the air traps are completely relieved from
the fiber stacks. The laminate is then allowed to cure for
15–20 h and then it is removed from the glass table and it
is kept inside a weave with a temperature of 60 °C to
avoid the atmospheric moisture in the specimens.
2.4 Inter-laminar fracture toughness of unidirectional
fiber-reinforced polymer composites
The test method describes the Mode-I inter-laminar
fracture toughness. The test sample was prepared using
unidirectional glass fibers with 0° orientation. The speci-
men dimension is maintained as 125 mm length, 25 mm
width and a thickness of 3 mm. The test samples were
conditioned in an oven for 2–3 h to remove the moisture.
The tests were conducted at 23 °C.
2.5 Tensile and flexural characteristics
The tensile and the flexural tests were carried out us-
ing ASTM D3039 and ASTM D790. The specimen di-
mensions of (175 × 25 × 2) mm for tensile and the gauge
length are maintained as 115 mm and (125 × 12.7 × 3) mm
for flexural test. The tensile and the flexural behaviors of
the material were estimated for determining the yield
stress and the modulus of elasticity of the composite ma-
terial with the addition of filler. The obtained values
were incorporated in the FEA for identifying the
delamination characteristics of the material in different
loading conditions in the analysis software. The tensile
R. KARTHIKEYAN, S. RAJKUMAR: INVESTIGATION OF THE EFFECT OF INCONEL PARTICULATE FILLER ...
Materiali in tehnologije / Materials and technology 56 (2022) 6, 653–659 655
Table 2: Chemical compositions of the Inconel 718 filler (w/%)
Element Ni Cr Fe Nb Mo Ti Co Al Mg Si
Chemical com-
position
50.00–55.00 17.00–21.00 Balance 4.75–5.5 2.80–3.30 0.65–1.15  1.00 0.20–0.80  0.35  0.35
Figure1: Distribution of the epoxy resin under the vacuum-infusion
process (VIP)

test was carried out for four different groups of the filler.
A 100-t servo hydraulic UTM machine was used to exe-
cute the testing. The cross-head speed was maintained at
1mm/min to evaluate the tensile strength of the compos-
ite material.
2.6 Finite-element validation for determining the
delamination effect on the samples
The composite samples were designed using the
Ansys design modeler 19.1. The material input data were
used for the delamination analysis. The section of the
prepared sample was spliced into two equal halves for
maintaining a displacement in the solver module for de-
termining the delamination force. The glass fabric was
selected in the fabric selection tab and the element sets
were generated with the three element sets were gener-
ated namely open interface, total interface and total ele-
ment. The oriented element sets were also prepared for
the top, bottom and the open interface. Figure 2a shows
the sequential ply orientation from the top to the bottom
and Figure 2b shows the interface delamination zone.
The entire setup was validated and the results were iter-
ated with the static structural modular with the fracture
and module ply interface delamination. The setup was
initiated with the specific constraints for the loading op-
erations for determining the delamination effects in the
fiber and the matrix. Gu et al. explained the application
of the FEA for determining the delamination in the ma-
trix, particularly at the free edges. The current finite-ele-
ment validation focus on the interfacial crack in the lami-
nates for determining the delamination characteristics of
the Inconel particulate filled material.
16
Figure 2a shows the load constraints for performing
the deformation analysis of the generated composite ma-
terial from Ansys – ACP modeler. Figure 2b denotes the
overall deflection with reference to the applied load from
the obtained mechanical data.
2.7 Water absorption
The contact-angle measurement was carried out for
the water-absorption characteristics of the Inconel rein-
forced (glass-fiber-reinforced plastic) GFRP composites.
The contact-angle analysis provides information about
the material, whether hydrophobic or hydrophilic in na-
ture. The measurement was made with the sessile drop
method.
2.8 Flammability test
The flammability characteristics of the Inconel-in-
fused GFRP composites were tested using the UL–94
standard for both the horizontal burn test (HBT) and the
vertical burn test (VBT). The results were calculated as
per the standard for the burn rate and the type of material
based on the specification included in the standard.
3 RESULTS AND DISCUSSION
The tensile results of the samples with Inconel 718 of
(1, 3 and 5) w/%, shows variable results with progressive
increments in the stress values.
Table 3: Tensile properties and flexural modulus of the GFRP with (1,
3 and 5) w/% of Inconel 718 as filler
Sample
Ultimate
load
(kN)
Tensile
strength
(MPa)
Young’s
modulus
(GPa)
Flexural
modulus
(GPa)
GF + Epoxy 13.334 209 3.892 14.7690
1 % Inconel + GF 25.121 395 4.865 19.1371
3 % Inconel + GF 22.987 362 4.447 12.7112
5 % Inconel + GF 17.715 278 3.390 12.1531
The tensile strength along with the elongation was es-
timated from the S–S curve and the flexural modulus
was tabulated in Table 3. From the graph it is understood
that the tensile strength of the composite material with
1 w/% Inconel content is higher than the normally used
GFRP without filler content. The modulus value tends to
decrease with an increase in the filler content by
1–5 w/%. The modulus value of the GFRP is in the range
of 3.8 GPa, and with the addition of 1 w/% Inconel filler
it increased to 4.8 GPa. This value of the addition of
R. KARTHIKEYAN, S. RAJKUMAR: INVESTIGATION OF THE EFFECT OF INCONEL PARTICULATE FILLER ...
656 Materiali in tehnologije / Materials and technology 56 (2022) 6, 653–659
Figure 2: Delamination test using FEA: a) load constraints, b) defor-
mation

Inconel filler shows an effective increment of the
Young’s modulus. The modulus value tends to decrease
by 3 w/% and 5 w/% due to the increased quantity of
filler powder dispersed between the fiber and the matrix,
thus making a material with increased stiffness. The
amount of filler content added to the matrix plays a vital
role in deciding the material for a specific application.
Sehajpal et al. discussed how the usage of increased
metal fillers in poly-methyl-methacrylate (PMMA) and
other resins can reduce the tensile and the flexural prop-
erties of the composite materials with the PMMA as a
matrix material. In the above case, the epoxy resin is
used as the matrix with Inconel as the filler. The flexural
properties tend to decrease with an increase in the filler
rate, this is because the concentration of the filler affects
the flexibility of the material by increasing the toughness
of the material.
17
The elastic modulus of about 60 % de-
creased by 1–3 w/% of filler content and about5%for
3–5 w/% respectively, this effect may be due to the surge
in the Inconel particles to the matrix affecting the elastic
modulus, the micro grains of the Inconel powder makes
the matrix and the fiber to improve the bonding strength
by suppressing the elastic modulus. Figure 3 shows an
SEM micrograph of the Inconel filled GFRP composite
of the tested specimen. The micrograph clearly shows
the improved fiber matrix interaction due to the addition
of the Inconel particles. The Inconel particles were
closely attached to the fiber matrix interface, enabling
the fiber to de-bond from the matrix and improving the
delamination strength.
Figure 4 shows the von Mises stress with respect to
the pulling force for different Inconel proportions. From
the graph it is clear that the GF with epoxy had a pulling
force of 1.005 kN, a stress intensity of the GFRP without
the addition of fillers is 783 MPa, 1 w/% filled Inconel
sample showed an increased pulling force of 1.035 kN,
the stress intensity on the top and bottom layers was
851 MPa. The fiber volume fraction of the Inconel filled
GFRP material showed 64 %. The test was carried out
using the resin-burning-off method. The remaining per-
centage of 36 % is made up with the epoxy resin and
Inconel filler.
The increased stress values were due to the increase
in the pull force originating from the ply layers. Simi-
larly, the deformation and the pulling force values were
identical for the next series of proportions. The stress
values were found to be reduced for the 3 w/% and
5 w/% Inconel content, it has been clearly understood
from the Figure 4, that the increased Inconel content re-
duced the stress values and the bonding strength between
the fiber and the matrix. A ply of suitable thickness as
per the standard is oriented in the Ansys ACP, 6 layer of
thickness of 3 mm with 0.5 mm individual ply thickness
was layered one over the other with the fiber and ep-
oxy-resin matrix. The contours from the finite-element
method showed the von Mises stress without the addition
of filler experiencing higher stress at the bend region on
the middle region of the ply, the shear stress at the bend-
ing region was recorded as 93.74 MPa in the peeling di-
rection (YZ-orientation). The correlation between the
shear stress, deflection and von Mises stress resembles
the delamination strength has increased with the addition
of the Inconel filler. The results showed a reduction of
0.15 MPa in the shear stress, making the specimen mod-
erately brittle with the addition of the Inconel powder.
The water-absorption characteristics of the Inconel filled
GFRP composites was identified using the sessile drop
method, with the contact-angle values shown in Fig-
ure 5. The contact angle with the Inconel-filled compos-
ites showed a steadily improving curve. The results
showed a reduced value for the 0 w/% and 1 w/% Inconel
with hydrophilic characteristics and 3 w/% and 5 w/%
Inconel with hydrophobic characteristics.
The addition of the Inconel filler improved the wa-
ter-absorption characteristics by 11–12 % from the origi-
nal value. The flammability test was considered as the
important material testing for analyzing the fire-retardant
R. KARTHIKEYAN, S. RAJKUMAR: INVESTIGATION OF THE EFFECT OF INCONEL PARTICULATE FILLER ...
Materiali in tehnologije / Materials and technology 56 (2022) 6, 653–659 657
Figure 3: SEM micrograph of the broken GFRP with Inconel 718
filler
Figure 4: FEA validation results showing the von-Mises stress plot
for different Inconel proportions

characteristics of the composite material. The current
flammability test ensures the effect of the addition of the
Inconel filler for different proportions. Figure 6 shows
the linear burn rate in the horizontal orientation in
mm/sec for the unfilled and the filled Inconel GFRP
composites. From the figure it is clear that the rate of
burning reduced from 35.4 mm/s to 10.80 mm/s, nearly
69 % of the flame-retardant characteristics improved
with the addition of the Inconel filler.
The requirement of the composite materials in vari-
ous automotive domains has a serious impact on the ther-
mal and flammability characteristics. In order to ensure
better flame-retardant characteristics the UL-94 standard
was prescribed for detailing the end requirement of the
materials. The burn rate was measured in terms of the
formula derived with the time and damaged length of the
specimen. The linear burning rate is calculated using the
Equation (3).
V = 60(L/t) (3)
where V is the linear burning rate in mm/minute, L is the
damaged length in mm, t is the time in s. As per the for-
mula the linear burning rate was calculated and the ver-
tical burn rate was tabulated in Table 4.
From the burn-rate results, the vertical burn rate was
on the scale of V-2 with a burn time of 251–255 s, with
no single drop to ignite the cotton.
4 CONCLUSIONS
The material characteristics and the mechanical prop-
erties of the Inconel 718 filled GFRP composites were
successfully investigated with a series of mechanical val-
idations and testing. The tensile and the elastic modulus
results of the samples with Inconel of 1% showed better
results when compared with the unfilled GFRP. The FEA
validated results showed that the shear stress was re-
duced in the YZ orientation along the peeling direction,
R. KARTHIKEYAN, S. RAJKUMAR: INVESTIGATION OF THE EFFECT OF INCONEL PARTICULATE FILLER ...
658 Materiali in tehnologije / Materials and technology 56 (2022) 6, 653–659
Figure 5: Contact-angle dependence on different percentages for the
Inconel 718 filled GFRP composites
Figure 6: Inconel-filled GFRP composites: a) linear burn rate, b) horizontal burn-tested specimen
Table 4: Burn rate of the GFRP with epoxy and (1, 3 and 5) w/% of Inconel 718 filler
Sample No.
Inconel 718
(w/%)
Damaged length
(mm)
Time (s)
Linear burning
rate (mm/sec)
Combustion
level
Laminates self-extinguished
after flame removal
1 0 25 59 35.4 V-2 NO
2 1 35 73 28.76 V-2 NO
3 3 15 50 18.30 V-2 NO
4 5 13 72 10.80 V-2 NO

which enhanced the bonding strength between the fiber
and the matrix with Inconel 718 filler. It was observed
that the material had a brittle nature with the addition of
the filler. The delamination strength and the shear stress
were found to be higher for the 1 w/% Inconel 718 con-
tent. The contact-angle analysis of the unfilled and filled
GFRP showed higher values for the 5 w/% Inconel 718
filled material compared to the 1 w/% and 3 w/% , the
contact angle of 5 w/% filler was 116.30°, the incorpora-
tion of the Inconel 718 alloy with the epoxy matrix has
the same characteristics as the metal oxides. The hydro-
phobic characteristics were improved with the addition
of the metal alloys with the epoxy coatings, thus en-
abling the material to behave as hydrophobic in nature.
The flammability characteristics of the 5 w/% Inconel
718 filled material showed reduced linear burn rates of
10.80 mm/min. The VBT showed V-2 inference as the
flame is not self-extinguishing up to 251–255 s. The in-
creased VBT range is due to the fiber and the matrix
cross-orientation causing the material to burn with a little
smoke. Thus, the overall results showed an increase in
the Inconel 718 material enhanced the mechanical and
flammability characteristics of the GFRP composite lam-
inates.
5 REFERENCES
1
A. Delbariani-Nejad, A. Farrokhabadi, S. R. Jafari, An energy based
approach for reliability analysis of delamination growth under mode
I, mode II and mixed mode I/II loading in composite laminates, Int.
J. Mech. Sci., 145 (2018), 287–298, doi:10.1016/j.ijmecsci.2018.
07.017
2
C. Dong, Effects of process-induced voids on the properties of fibre
reinforced composites, J. Mater. Sci. Technol., 32 (2016) 7, 597–604,
doi:10.1016/j.jmst.2016.04.011
3
S. Yentl, L. Gorbatikh, I. Verpoest, Fibre hybridisation in polymer
composites: A review, Composites Part A., 67 (2014), 181–200,
doi:10.1016/j.compositesa.2014.08.027
4
F. Mohamad, S. Sadeghi, M. Jalalvand, M. Ahmadi, Analysis of the
damage mechanisms in mixed-mode delamination of laminated com-
posites using acoustic emission data clustering, J. Thermoplast.
Compos. Mater., 30 (2017) 3, 318–340, doi:10.1177/
0892705715598362
5
P-C. Ma, Y. Zhang, Perspectives of carbon nanotubes/polymer
nanocomposites for wind blade materials, Renewable Sustainable
Energy Rev., 30 (2014), 651–660, doi:10.1016/j.rser.2013.11.008
6
S. R. Reid, Z. Zou, S. Li, P. D. Soden, Application of a delamination
model to laminated composite structures, Composite Structures, 56
(2002) 4, 375–389, doi:10.1016/S0263-8223(02)00021-1
7
I. Hiroaki, M. Arai, K.Takeyama, N. Hu, M. Quaresimin, Impact
damage and residual compression strength of CNF/CFRP hybrid
laminates, Journal of Solid Mechanics and Materials Engineering, 7
(2013) 3, 381–393, doi:10.1299/jmmp.7.381
8
Z-Z. Zhang, Q-J, Xue, W-M. Liu,W-C. Shen, Friction and wear prop-
erties of metal powder filled PTFE composites under oil lubricated
conditions, Wear, 210 (1997) 1–2, 151–156, doi:10.1016/S0043-
1648(97)00052-5
9
Z. J. Pan, J. Z Wu, J. Liu, X. H. Zhao, Fatigue failure of a composite
wind turbine blade at the trailing edge, Defect and Diffusion Forum,
382 (2018), 191–195, doi:10.4028/www.scientific.net/DDF.382.191
10
Y. J. Liu, Z. Jiang, H. M. Wen, Predicting impact induced delami-
nation of FRP laminates, Int. J. Impact Eng.,137 (2020), 103436,
doi:10.1016/j.ijimpeng.2019.103436
11
J. Wilk, Development and implementation of a testing method for the
characterization of interlaminar delamination propagation in lami-
nates under fatigue mode II loading conditions, Transactions of the
institute of aviation, 4 (2016) 245, 251–256, doi:10.5604/
05096669.1226901
12
R. Cortés, N. K. Rodríguez, R. R. Ambriz, V. H. López, A. Ruiz, D.
Jaramillo, Fatigue and crack growth behavior of Inconel
718–AL6XN dissimilar welds, Mater. Sci. Eng, A., 745 (2019),
20–30, doi:10.1016/j.msea.2018.12.087
13
N. Gupta, B. S. Brar, E. Woldesenbet, Effect of filler addition on the
compressive and impact properties of glass fibre reinforced epoxy,
Bull. Mater. Sci., 24 (2001), 219–223, doi:10.1007/BF02710105
14
G. Pincheira, N. Ferrada, J. Hinojosa, G. Montecino, L. Torres, K.
Saavedra, A study of interlaminar properties for a unidirectional
glass fiber reinforced epoxy composite, Proc. Inst. Mech. Eng., Part
L: J. Mater. Des. Appl., 233 (2019) 3, 348–357, doi:10.1177/
1464420718816731
15
B. Yang, Y. Mao, Y. Zhang, Y. Wei, W. Liu, Y. Qiu, Fast-curing halo-
gen-free flame-retardant epoxy resins and their application in glass
fiber-reinforced composites, Text. Res. J., 89 (2018) 18, 3700–3707,
doi:10.1177/0040517518819845
16
J. Gu, Z. M. Huang, Assessing delamination initiation of angle-ply
laminates from fiber and matrix properties, J. Thermoplast. Compos.
Mater., 32 (2018) 12, 1601–1621, doi:10.1177/0892705718799840
17
S. B. Sehajpal, V. K. Sood, Effect of metal fillers on some physical
properties of acrylic resin, The Journal of prosthetic dentistry, 61
(1989) 6, 746–751, doi:10.1016/s0022-3913(89)80055-1
R. KARTHIKEYAN, S. RAJKUMAR: INVESTIGATION OF THE EFFECT OF INCONEL PARTICULATE FILLER ...
Materiali in tehnologije / Materials and technology 56 (2022) 6, 653–659 659