Determination of residual stresses of welded joints prepared under

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME
542
DETERMINATION OF RESIDUAL STRESSES OF WELDED JOINTS
PREPARED UNDER THE INFLUENCE OF MECHANICAL
VIBRATIONS BY HOLE DRILLING METHOD AND COMPARED BY
FINITE ELEMENT ANALYSIS
1
P. Govinda Rao, 2
Dr. C L V R S V Prasad, 3
Dr.D.Sreeramulu,
4
Dr.V. Chitti Babu, 5
M.Vykunta Rao
1,3
Associate Professor in the Department of Mechanical Engineering,
GMR Institute of Technology,
2
Principal, GMR Institute of Technology,
3
Professor & Associate Dean, Centurion University,
5
Asst.Professor in the Mechanical Engineering Department, GMR Institute of Technology
ABSTRACT
Welded joints are used for construction of many structures. Welding is a joining or
repair process which induces high residual stress field, which combines with stresses
resulting from in-service loads, strongly influencing in-service behavior of welded
components. When compared with stresses due to service loads, tensile residual stress
reduces crack initiation life, accelerates growth rate of pre-existing or service-induced
defects, and increases the susceptibility of structure to failure by fracture. Also, welding
residual stresses are formed in a structure as a result of differential contractions which occur
as the weld metal solidifies and cools to ambient temperature.
Previously some of the methods like heat treatment and peening kind techniques were
used for reduction of residual stress. However, those methods need special equipment and are
time consuming. In this, we are proposing a new method for reduction of residual stress using
vibration during welding. For this Mechanical vibrations will be used as vibration load. In
this work, Finite Element Method (FEM) will be used for assessment of welding residual
stresses and comparison of experimental results with FEM results for Mild steel butt welded
joints [2].
INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING
AND TECHNOLOGY (IJMET)
ISSN 0976 – 6340 (Print)
ISSN 0976 – 6359 (Online)
Volume 4, Issue 2, March - April (2013), pp. 542-553
© IAEME: www.iaeme.com/ijmet.asp
Journal Impact Factor (2013): 5.7731 (Calculated by GISI)
www.jifactor.com
IJMET
© I A E M E

543
Keywords: Welding, Vibration, Residual stress, Finite element method.
I. INTRODUCTION
Welding is widely used for construction of many structures. Since welding is a
process using locally given heat, residual stress is generated near the bead. Residual stresses
are defined as the stresses which remain within a structure when all external loads or
reactions are removed, hence they must be self-balanced within the structure itself.
It is well accepted that the residual stresses commonly arise from permanent changes
in the shape of the body. The residual stresses generated during welding may hamper the
functional efficiency of the component leading to failure of the engineering structures. It may
also lead to brittle fracture of the welded structures causing enormous damage to resources
and loss of human life.
Residual stresses are the major constituents of a stress field around a crack which
may lead to cracking. Tensile residual stresses reduce fatigue strength and corrosion
resistance while compressive residual stresses diminish the stability limit. Also, while tensile
residual stresses may initiate the failure due to fracture, the compressive residual stresses near
a weld can reduce the capacity of the structural member in buckling and collapsing.
Some reduction methods of residual stress have been presented for example, heat
treatment and shot peening techniques are used. However, those methods need special
equipment and are time consuming. In this, we are proposing a new method for reduction of
residual stress using vibration during welding.
II. PROBLEM DEFINITION
1. Earlier times heat treatment and shot peening are practically used for reduction of
residual stresses, However, those methods need special tools and time consuming.
2. In this paper a new method for reduction of residual stresses using vibrational load
during welding.
3. Estimation of residual stresses nearer to weld bead in two directions (i.e.
Longitudinal and Transverse direction i.e. on the bead).
4. Two thin plates are supported to supporting device and are butt welded by using Arc
welding machine.
5. Residual stresses in the direction of bead is measured by using Multi channel strain
indicator strain values are obtained.
6. These results are converted to stress values by hole drilling method, later on Finite
element Method is used to compare the practical values in Ansys.

544
III. EXPERIMENTAL SETUP
Reduction of residual stress on both sides of the specimen using vibrational load is
examined experimentally. Fig. 1. shows the specimen used in this experiment. Material of
specimen is Mild steel(Is2062) Two thin plates are supported on to supporting devices by
bolts as shown in fig.1. Specimens are vibrated by a vibromotor during welding specimens
are butt-welded using an arc welding machine. In order to examine the effect on excitation
frequency on reduction residual stress amplitudes of excitation frequencies are chosen as
70,80, 84 and 90Hz. The frequencies are measured by the vibrometer . Size and shape of
specimen made of mild steel for general structure (mm) in fig 2.
Fig.1 Supporting device for welding
Fig. 2 Size and shape of specimen made of mild steel for general structure
After completion of welding the specimens are taken to the multi channel strain
indicator for measuring strains. In this method, therefore, strain gauges in the form of a three
element rosette are placed in the area under consideration. A through-thickness hole is
drilled in the centre of the strain gauge rosette. In this way the residual stresses in the area
surrounding the drilled hole are relaxed and the relieved radial strains can be measured with a
suitable multi channel strain gauge.

545
Fig.3. The strain gauges are bonded to the specimens
Fig.2 Strains are measured by Multi Channel Strain Indicator shown in
IV. CALCULATION
Hole drilling Method: According to this popular and well established method residual stress
is determined by measuring the relieved radial strain when drilling a small through-hole into
the weld plate. Two principal stresses
V. OBSERVATIONS
From the above experimental setup, through the multi channel strain indicator the
following are the observations of residual stresses values are shown in tables.

546
Table 1. Residual stress values at different frequencies at first side perpendicular to
the bead
Table 2. Residual stress values at different frequencies at first side parallel to the bead
Table 3. Residual stress values at different frequencies at second side perpendicular to the
bead

547
1
MN
MX
X
Y
Z
-.550E+09
-.472E+09
-.394E+09
-.316E+09
-.239E+09
-.161E+09
-.832E+08
-.547E+07
.723E+08
.150E+09
JUN 2 2012
14:01:14
NODAL SOLUTION
STEP=1
SUB =3
FREQ=84.2
REAL ONLY
/EXPANDED
SX (AVG)
RSYS=0
DMX =.319E-03
SMN =-.550E+09
SMX =.150E+09
Table 4. Residual stress values at different frequencies at second side parallel to the bead
VI. FINITE ELEMENT MODEL
The welding process of a butt-weld joint of two IS2062 mild steel plates with the
dimensions shown in Fig.1 was simulated. Due to high temperature and stress gradients near
the weld, the finite element model has a relatively fine mesh in both sides of the weld center
line. The eight-node brick elements with linear shape functions are used in meshing the
model. To simulate the moving heat source it is necessary to model the heat source during
each time increment. In this analysis the moving heat source is simplified by assuming the
welding arc stayed at an element with a constant specific volume heat generation, and then
moved to the next element at the end of the load step as the welding was finished. The
element type SOLID70, which has a single degree of freedom, was used for the thermal
analysis. For the structural analysis the element type SOLID45, with three translational
degree of freedom at each node, was used. The geometry model is shown in fig 1 and
Temperature distribution graph is shown in fig 2&3 and Residual stresses graph are shown in
4&5.
Fig.1 Geometry of the model used in the Fig 2. Temperature distribution first side
Analysis of welding

548
Fig.3. Temperature distribution second side Fig 4. Residual stresses at first side
of welding welding
Fig 5. Residual stresses at second side welding
VII. RESULTS AND ANALYSIS
From the above observations tables the residual values are analyses and are shown in
graphs
Graph.1. Residual stress values at different frequencies at first side perpendicular to the bead
1
MX
X
Y
Z
temperature distribution after second side of welding
27
267.252
507.504
747.757
988.009
1228
1469
1709
1949
2189
MAY 21 2012
10:55:35
NODAL SOLUTION
STEP=1
SUB =1
TIME=40
/EXPANDED
BFETEMP (AVG)
RSYS=0
DMX =.570E-03
SMN =27
SMX =2189
1
MN
MX
X
Y
Z
-.570E+09
-.486E+09
-.402E+09
-.317E+09
-.233E+09
-.149E+09
-.648E+08
.194E+08
.104E+09
.188E+09
JUN 2 2012
12:27:23
NODAL SOLUTION
STEP=1
SUB =1
TIME=20
/EXPANDED
SX (AVG)
RSYS=0
DMX =.337E-03
SMN =-.570E+09
SMX =.188E+09
1
MN
MX
X
Y
Z
27
207.74
388.48
569.22
749.96
930.7
1111
1292
1473
1654
APR 1 2012
22:52:22
NODAL SOLUTION
STEP=20
SUB =1
TIME=20
/EXPANDED
TEMP (AVG)
RSYS=0
SMN =27
SMX =1654

549
Graph.2. Residual stress values at different frequencies at first side parallel to the bead
Graph.3. Residual stress values at different frequencies at second side perpendicular to the
bead
Graph.4. Residual stress values at different frequencies at second side parallel to the bead

550
VIII. COMPARISON OF PRACTICAL AND ANSYS VALUES
Taking the experimental and Analysis results are shown in below Tables
Table 1. Residual stress values at different frequencies at first side perpendicular to the bead
Table 2. Residual stress values at different frequencies at first side parallel to the bead
Table 3. Residual stress values at different frequencies at second side perpendicular to the
bead

551
Table 4. Residual stress values at different frequencies at second side parallel to the bead.
From the above experimental results and Ansys results the error are calculated
between the above tables. The residual stress are shown in below graphs
Graph 1. Residual stress values at different frequencies at first side perpendicular to the bead
.
Graph.2. Residual stress values at different frequencies at first side parallel to the bead

552
Graph. 3. Residual stress values at different frequencies at second side perpendicular to the
bead
Graph.4. Residual stress values at different frequencies at second side parallel to the bead
IX. CONCLUSION
1. A new method for reduction of residual stresses vibrational load during welding is
proposed. The proposed method is examined experimentally for some conditions. Two thin
plates are supported on the supporting device and butt welded.
2. By doing the experimentation the natural frequency was found by using at 70Hz, 80Hz,
and 84Hz. For these frequencies residual stresses greatly reduced at natural frequency of
84Hz.
3. Second-side welding process was performed for which the residual stress slightly increased
from 77Mpa to 78Mpa.
4. In this work welding of FEM was performed for mild steel IS2062 by using thermal and
structural analysis to find out the residual stresses.
5. The residual stresses were found by using Finite Element software for mild steel IS2062 is
118Mpa.
6. Hence residual stresses can be greatly reduced by maintaining frequency of forced
vibration nearer to the natural frequency of the specimen.

553
X. REFERENCES
[1]. Shigru Aoki and Tadashi Nishimura, “Reduction method for residual stress of welded
joint using random vibration 235(2005) .
[2] Shigru Aoki Tadashi Nishimura Tetsumaro Hiroi Seiji Hirai “Reduction method for
residual stresses weld joints using Harmonic vibrational load”, Nuclear Engineering design
237(2007).
[3]. LIYAJIALG and WANG JUAN, ”Finite element analysis of Residual stress in the
welded zone of a high strength steel” Bull Mater.Sci.Vol 27,Nov2, April 2004 pp.127-132@
Indian Academy of sciences.
[4]. Dragistamenkovic and Ivana Vasovic, ”Finite Element Analysis of Residual stress in Butt
welding Two similar plates” Scientific technical review, Vol LIX No,2009.
[5].Tso-Liang Teng and Peng-Hsiang Chang, “Effect of Welding Sequences on stress”,
Received 26 March 2002 Accept to Novmber 2002.
[6]. Anna Paradowska and John W.H. Price, “A neutron diffraction study of residual stress
due to welding”, Journal of Materials Processing Technology 164–165 (2005) 1099–1105.
[7].Dean Deng and Shoichi Kiyoshima,” FEM prediction of welding residual stresses in a
SUS304 girth-welded pipe with emphasis on stress distribution near weld start/end location”,
Computational Materials Science 50 (2010) 612–621.
[8].R.V. Preston and H.R. Shercliff, “Physically-based constitutive modeling of residual
stress development in welding of aluminium alloy 2024”, Received 10 June 2003; received
in revised form 11 June 2004; accepted 14 June 2004 Available online 10 August 2004.
[9] Harshal K. Chavan, Gunwant D. Shelake and Dr. M. S. Kadam, “Finite Element Model to
Predict Residual Stresses in MIG Welding”, International Journal of Mechanical Engineering
& Technology (IJMET), Volume 3, Issue 3, 2012, pp. 350 - 361, ISSN Print: 0976 – 6340,
ISSN Online: 0976 – 6359.
[10] R S Rajpurohit and R S Prasad, “Analysis of Mechanical Structure under Vibration
using Vibration Measuring System”, International Journal of Mechanical Engineering &
Technology (IJMET), Volume 4, Issue 1, 2013, pp. 134 - 141, ISSN Print: 0976 – 6340,
ISSN Online: 0976 – 6359.

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