Determination of Residual Stresses of Welded Joints Prepared Under

7/28/2019 Determination of Residual Stresses of Welded Joints Prepared Under

1/12

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 BYFINITE ELEMENT ANALYSIS

1P. Govinda Rao,

2Dr. C L V R S V Prasad,

3Dr.D.Sreeramulu,

4Dr.V. Chitti Babu,

5M.Vykunta Rao

1,3Associate Professor in the Department of Mechanical Engineering,

GMR Institute of Technology,2

Principal, GMR Institute of Technology,3

Professor & Associate Dean, Centurion University,5Asst.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.aspJournal Impact Factor (2013): 5.7731 (Calculated by GISI)

www.jifactor.com

IJMET

I A E M E


2/12



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 tensileresidual 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 ofresidual stresses, However, those methods need special tools and time consuming.

2. In this paper a new method for reduction of residual stresses using vibrational loadduring 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 Arcwelding machine.

5. Residual stresses in the direction of bead is measured by using Multi channel strainindicator strain values are obtained.

6. These results are converted to stress values by hole drilling method, later on Finiteelement Method is used to compare the practical values in Ansys.


3/12



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 ofspecimen 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.


4/12



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.


5/12



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


6/12



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 thermalanalysis. 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


7/12



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

27267.252

507.504747.757

988.0091228

14691709

19492189

MAY 21 2012

10:55:35

NODAL SOLUTION

STEP=1

SUB =1

TIME=40

/EXPANDED

BFETEMP (AVG)

RSYS=0

DMX =.570E-03

SMN =27SMX =2189

1

MNMX

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

MXX

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


8/12



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 thebead

Graph.4. Residual stress values at different frequencies at second side parallel to the bead


9/12



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


10/12



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 calculatedbetween 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


11/12



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 increasedfrom 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.


12/12



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 164165 (2005) 10991105.[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) 612621.

[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.

Documents

Determination of Residual Stresses of Welded Joints Prepared Under