Effect of Various Parameters on Double Lap Bolted GFRP-to-Steel Joint by Experimentally and Numerically

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 2312
Effect of various parameters on double lap bolted GFRP-to-steel joint
by experimentally and numerically
Amol N. Kadam1, S. M. Ingale2
1Research Scholar, Dept. of Mechanical Engineering, SGI Atrigre, 416118, India,
2Associate Professor, Dept. of Mechanical Engineering, SGI Atrigre, 416118, India.
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Abstract- In structural applications such as in aircraft,
space craft and in civil engineering structures the
components are often fasten to the structural members by
threaded fasteners to maintain integrity in fastened
structure due to their high reliability, strong load bearing
capacity, easier to assemble and disassemble, more tolerant
to environmental damages and helpful in preventing
interlamination. The bolted joints are carefully designed
due to the stress concentration at the surrounding of the
hole. It is well known that stress concentrations near the
fastener holes could initiate delamination, which severely
reduces the strength of the structure. The bolted joint
strength is also affect by parameters such as joint
configuration, joint geometry, loading conditions, etc. The
present work is focused on analyzing effect of various
parameters such as washer outer diameter sizes, preload,
and edge to hole diameter ratio on the strength of double
lap bolted joint structure subjected to tensile loading by
using experimental and numerically. The numerical results
were found in good agreement with the experimental
results.
Keywords: bolted joint, double lap, GFRP, strength
Nomenclature:
L Length of plate
W Width of Plates
D Minimum hole diameter
Plate thickness of GFRP plate
Plate thickness of steel plate
E Edge distance
p centre to centre distance between two bolts
T Tightening torque
Washer outer diameter size
Preload
FEA Finite Element Analysis
FEM Finite Element Method
1. INTRODUCTION
In general, built-up structures are the combinations of
different types of joining. The method of assembly is
important consideration in design of built-up structures. In
structural applications such as in aircraft, space craft and in
civil engineering structures the components are often
fasten to the structural members by threaded fasteners to
maintain integrity in fastened structure. In general,
increase in bolt-fastening forces lead increase in joint
strength compared to the other joints because it is
relatively more reliable to transfer higher loads, easier to
assemble and disassemble, more tolerant to environmental
damages and helpful in preventing interlamination. The
bolted joints are carefully designed due to the stress
concentration at the surrounding of the hole. It is well
known that stress concentrations near the fastener holes
could initiate delamination, which severely reduces the
strength of the structure. The bolted joint strength is also
affect by parameters such as joint configuration, joint
geometry, loading conditions, fastening parameters, and
material parameters. The main objective of this paper is to
study the effects of washer outer diameter size, preload,
and edge to hole diameter ratio on strength of double lap
single bolted joint using experimentally and finite element
analysis.
2. LITERATURE REVIEW
Tajeuna et. al.[1] studied the effect of geometrical
parameters of Al-to-steel bolted connections to predict the
optimal geometric configuration foe single-lap and double-
lap bolted connections by experimentally and numerically.
P.A. Sharos et. al. [2] was predicts the strength of multi-
bolted composite joint at various loading rates by
analytically using damage approximation function. V.P.
Lawlor et. al. [3] was studied the effect of variable clearance
in multi-bolt, double lap, composite joint on load
distribution, quasi-static strength, fatigue life and failure
modes by experimentally. U.A. Khashaba et. al. [4] was
studied the effect washer size and tightening torque on the
performance of bolted joints in [0/±45/90] glass fiber
reinforced epoxy (GFRE) composites and determined the
mechanical properties (tensile, compressive, and in-plan
shear) of GFRE laminates by experimentally and
theoretically. M.P.Cavatorta et. al. [5] described a finite
element simulation and experimental validation of a
composite bolted joint loaded in bending and torsion. Ali
Najafi et. al. [6] studied the failure behavior of bolted joints
including failure mode, failure load and joint stiffness
through finite element simulation embedded in progressive
failure analysis (PFA). T.N.Chakherlou et. al. [7] studied the
effect of the clamping force variation in interference fitted
double shear lap bolted joints of aluminum 2024-T3 under
static and cyclic loads by experimentally and also FE
analysis was performed to compare with experiments of

the static loading. Kunliang Liu et. al. [8] studied the effects
of pre-tightening force and connection mode on the
strength and progressive damage of composite laminates
with bolted joints by FE analysis and compares their results
with analytical results. Jong-Hwa Yun et. al. [9] was
evaluated the new method for improving the strength of
multi-bolted joints by considering the effect of hole
clearance by experimentally and FEA. Faruk Sen et. al. [10]
performed an experimental failure analysis to determine
the failure behavior of bolted composite joint under various
preload moments, two different geometrical parameters
(edge- to-hole dia. ratio (E/D) and plate width-to-hole dia.
Ratio (W/D)) and ply orientations. Fengrui Liu et. al. [11]
was developed an analytical tri-linear joint stiffness model
for load transfer analysis in highly torque multi-bolt
composite joints with clearance.
3. EXPERIMENTAL ANALYSES
The experimental analysis is carried out to measure
strength of double lap single bolted joint structures by
using computerised universal testing machine. The
schematic representation of experimental setup is shown in
fig.1.Experimental testing specimen containing two steel
plates and one GFRP plate is shown in fig. 2. The size of
plates, steel plate is 192mm X 40mm X 5mm and GFRP
plate is 192mm X 40mm X 2mm. To measure displacement
occurred in the joint during the experiment the gauge
length is marked on the GFRP plate.
Fig. 1 Experimental Setup
Fig. 2 Double lap Single bolted joint
A. Steps in Experimental Analysis
1. Take composite plate specimen and the gauge length is
marked on that to measure the total deflection
occurred after experiment.
2. Then the composite plate fastened with steel plates
with help of bolt to form double lap bolted joint.
3. The tightening torque is applied on bolt with help of
torque wrench to get required preload.
4. The bolted joint was clamped between the two jaws of
universal testing machine.
5. Suitable connections were made to get required
readings through computer.
6. The control panel of universal testing machine has two
operating valves at both ends to maintain required oil
pressure.
7. The tensile load was applied on the joint and maximum
load, total deflection and Ultimate strength was
measured.
8. Experiment setup was taken to the initial condition (i.e.
zero load condition).
9. The above procedure was repeated to calculate the
strength of the double lap single bolted structure by
varying following parameters such as,
a) Washer outer dia. size [20mm, 23mm and
30mm]
b) Preload [25KN, 30KN and 35 KN]
c) Edge to hole diameter ratio (E/D) [3, 4 and 5]
4. FINITE ELEMENT ANYLSIS
A. Configuration of test specimen
Similar to the experimental specimen, the FE model has six
basic components: two steel plates, GFRP plate, Washer,
Bolt and Nut as shown in fig.3. The solid model of specimen
is prepared by using Creo Parametric 2.0 software and the
model is saved in IGS file format. The solid model is
imported into ANSYS Workbench 16.0 for FEA.
Fig. 3 Double Lap Single Bolted Joint
B. Material Property
The1045 Steel for plate 1 and plate 3 and GFRP (Woven E-
Glass epoxy) for plate 2 and; Medium carbon alloy steel for
Nut and Bolt and alloy steel for Washer is used. The
material property of fastened plates is shown in Table 1and
Table 2.
Double lap
bolted joint
testing
specimen with
gauge length
mark on
GFRP plate
UTM
Control
System
Computer for
Recording Data

Density 7810 Kg/
Modulus Of Elasticity 201GPa
Poisson’s Ratio 0.3
Yield Strength 507MPa
Tangent Modulus 3350MPa
Tensile Ultimate Strength 250MPa
Tensile Ultimate Strength 460MPa
Table 1 Material Property of 1045 steel
Elastic properties
Young’s
modulus GPa
Poisson’s
ratio (µ)
Shear
modulus (G)
GPa
= 25GPa = 0.2
4 GPa= 25GPa =0.2
= 0.6E11GPa =0.2
Table 2 Material property of GFRP
C. Contact Conditions
There are seven contact interactions are established for all
contact surfaces in the finite element model are shown in
table 3.
Sr. No Contact Target
Type of
Interaction
1 Plate-2 Plate-1 Frictional
2 Plate-2 Plate-3 Frictional
3 Bolt Nut Bonded
4 Washer Plate-3 Frictional
5
All plate
holes
Bolt shank Frictional
6 Bolt Washer Frictional
7 Nut Plate-1 Frictional
Table 3 Contact conditions
D. Meshing
All components of bolted structure are meshed by using
Hex Dominant method with Quad/ tri mesh type having
mesh size 2mm with fine relevance and span angle centre.
There are total 83771 nodes and 15515 elements are
formed on meshing.
E. Boundary condition
All degrees of freedom of all nodes and elements of outer
left side surface of plate-1 and plate-3 is fixed support as
shown in Fig. 4.
F. Loading Conditions
From experimental test the value of peak load is get and
that amount of load is applied to one side of GFRP plate
which is shown in fig. 4. When bolt is tightening by
tightening torque, all the washer face of bolt head and nut
i.e. contact face transmit clamping force (Fc) to face of
washer and fastened plate i.e. target face respectively which
help to clamp fastened plates together as shown in Fig. 4.
The contact faces apply uniform distributed load on the
target faces. The applied clamping forces are equal in
magnitude but opposite in direction along axial direction of
bolt shank. Also the preload force (Fp) is applied on the
cylindrical surface of the bolt shank along the axial
direction which is equal in magnitude but opposite in
direction of each other as shown in Fig.4.
Clamping Force ( )
Bolt- Pretension = Preload ( )
Fig. 4 Fixed support and forces acting on bolted joint in FEA
5. RESULTS AND DISCUSSION
The results obtained from the experiment and finite
element analysis of double lap single bolted joint for
different parameters are discussed below,
A. Effect of Washer outer diameter size on bolted joint
strength
To see the effect of washer outer diameter size, the size is
varied as 20 mm, 23 mm and 30 mm and other parameter
of joint such as edge to hole dia. ratio, width to hole dia.
ratio, preload ,plate thickness, etc. are kept constant. The
maximum strength (max. stress) value obtained for single
bolted structures from experiment was validated using
ANSYS and the values are shown in the table 4.
Washer
size
(mm)
Peak
load
P
(KN)
Displacement
(mm)
Max. strength (MPa)
by using
Experimental FEM
20 26.76 0.6 655.31 784.1
23 26.16 0.85 639.15 755.7
30 25.56 1.1 625.92 751.82
Table 4 Comparison between experimental and FEM results
for diff. washer sizes

Fig. 5 Comparative graph of strength analysis of different
washer outer diameter sizes
Fig. 6 Simulation of FEA result for single bolted double lap
joint with 20 mm washer size
B. Effect of preload on bolted joint strength
The preload which is applied on structure is from the
tightening torque applied on the bolt and the expression is
shown as,
=
Where, = Preload
M = Tightening torque
k = constant k 0.2, for most small to medium size bolts
= Nominal diameter of bolt
The bolt is tightened by means of mechanical torque
wrench which is shown in fig.10. The torque applied in this
analysis are 50 Nm, 60 Nm and 70 Nm so the preload on the
bolt shank caused by these pre-torques are 25 KN, 30 KN
and 35 KN respectively to obtain their effects on strength of
bolted structure at other parameters are kept constant such
as, plate thickness, washer size, W/D ratio and E/D ratio.
The maximum strength (max. stress) value obtained for
single bolted structures from experiment was validated
using ANSYS and the values are shown in the table 5.
Tightening
Torque
T (Nm)
Preload
(KN)
Peak
load
P
(KN)
Disp.
(mm)
Max. strength
(MPa) by using
Exp. FEM
50
25
26.76 0.6 655.31 784.1
60
30
28.12 0.65 688.61 803.25
70
35
29.95 0.5 733.43 849.16
for diff. Preload
0
100
200
300
400
500
600
700
800
900
20 23 30
Strength(MPa)
Washer Outer Diameter Sizes (mm)
Experimental Method
Finite Element Method

preload
Fig. 10 Torque wrench
joint with preload 25 KN
C. Effect of edge to hole diameter (E/D) ratio on bolted
joint strength
The three different levels of E/D ratio were chosen as
shown in table 5 to find their effect on the strength of joint.
E/D
Peak
load
P
(KN)
Displacement
(mm)
Max. strength (MPa)
by using
Experimental FEM
3 26.76 0.6 655.31 784.1
4 28.00 1 685.67 813.75
5 28.78 1.5 704.29 828.89
for diff. E/D ratio
E/D ratio
The results show that the increasing E/D ratio affects the
strength bolted joint. The strength increases with the
increase in E/D ratio as shown in fig.14.
0
200
400
600
800
1000
25 30 35
Strength(MPa)
Preload (KN)
Experimental Method
0
200
400
600
800
1000
3 4 5
Strength(MPa)
E/D ratio
Experimental Method

joint with E/D ratio is 3
6. CONCLUSIONS
Due to the changes in the bolting parameters (joint
configuration, fastening parameters and geometrical
parameters) there is a significant change in strength of
bolted structure.
The effect of washer outer diameter sizes on the strength of
double lap bolted structure shows that when washer size
increases the strength of bolted joint decreases.
The effect of preloads on the strength of double lap bolted
structure shows that when preload increases the strength
of bolted joint increases.
The effect of edge to hole diameter ratios (E/D ratios) on
the strength of double lap bolted structure shows that
when E/D ratio increases the strength of bolted joint
increases.
The effect of width to hole diameter ratios (W/D ratios) on
the strength of double lap bolted structure shows that
when W/D ratio increases the strength of bolted joint
increases.
7. REFERENCES
1. Thérèse A.D. Tajeuna, Frédéric Légeron, Pierre
Labossière, Marc Demers, Sébastien Langlois,“Effect of
geometrical parameters of aluminum-to-steel bolted
connections”, Journal of Engineering Structures , Vol.
102,Nov. 2015, Pages 344-357.
2. P.A. Sharos, B. Egan, C.T. McCarthy, “An analytical
model for strength prediction in multi-bolt composite
joints at various loading rates”, Journal of Composite
structures, Vol.116, Sep.-Oct. 2014, Pages 300-310.
3. V.P. Lawlor, M.A. McCarthy, W.F. Stanley, “An
experimental study of bolt–hole clearance effects in
double-lap, multi-bolt composite joints”, Journal of
Composite structures, Vol.71, Issue 2, Nov. 2005, Pages
176-190.
4. U.A.Khashaba , H.E.M.Sallam , A.E.Al-Shorbagy, M.A. Sei,
“Effect of washer size and tightening torque on the
performance of bolted joints in composite structures”,
Journal of Composite structures, Vol.73, Issue 3 , Jun
2006, Pages 310-317.
5. M.P. Cavatorta, D.S. Paolino, L. Peroni, M. Rodino, “A
finite element simulation and experimental validation
of a composite bolted joint loaded in bending and
torsion”,Journal of Composites Part A: Applied Science
and Manufacturing, Vol.38, Issue 4, Apr. 2007, Pages
1251-1261.
6. Ali Najafi, Mohit Garg, Frank Abdi, “Failure Analysis of
Composite Bolted Joints in Tension”, American Institute
of Aeronautics and Astronautics, May 2009.
7. T.N. Chakherlou, Babak Abazadeh, “Investigating
clamping force variations in Al2024-T3 interference
fitted bolted joints under static and cyclic loading”,
Journal of Materials and designs, Vol.37, May 2012,
Pages 128-136.
8. Kunliang Liu, Ying Tie, Cheng Li, “Effects Of Pre-
Tightening Force And Connection Mode On The
Strength And Progressive Damage Of Composite
Laminates With Bolted Joints”, Journal of Materials
Physics and Mechanics, Vol. 18, Oct.2013,Pages 18-27.
9. Jong-Hwa Yun, Jin-Ho Choi, Jin-Hwe Kweon, “A study on
the strength improvement of the multi-bolted joint”,
Composite Structures, Volume 108, February
2014, Pages 409-416.
10. Faruk Sen, Onur Sayman, ResatnOzcan, Ramazan
Siyahkoc, “Failure Response of Single Bolted Composite
Joints Under Various Preload”, Indian Journal of
Engineering & Materials Sciences, Vol. 17, Feb 2010,
Pages 39-48.
11. Fengrui Liu, Jianyu Zhang, Libin Zhao, An Xin , Longwei
Zhou,“ An analytical joint stiffness model for load
transfer analysis in highly torqued multi-bolt
composite joints with clearances”, Journal of Composite
Structures , Vol. 131, Jun 2015, Pages 625-636.

Effect of Various Parameters on Double Lap Bolted GFRP-to-Steel Joint by Experimentally and Numerically

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