• Save
Determination of residual stresses of welded joints prepared under
Upcoming SlideShare
Loading in...5
×
 

Like this? Share it with your network

Share

Determination of residual stresses of welded joints prepared under

on

  • 607 views

 

Statistics

Views

Total Views
607
Views on SlideShare
607
Embed Views
0

Actions

Likes
0
Downloads
0
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Determination of residual stresses of welded joints prepared under Document Transcript

  • 1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME542DETERMINATION OF RESIDUAL STRESSES OF WELDED JOINTSPREPARED UNDER THE INFLUENCE OF MECHANICALVIBRATIONS BY HOLE DRILLING METHOD AND COMPARED BYFINITE ELEMENT ANALYSIS1P. Govinda Rao, 2Dr. C L V R S V Prasad, 3Dr.D.Sreeramulu,4Dr.V. Chitti Babu, 5M.Vykunta Rao1,3Associate Professor in the Department of Mechanical Engineering,GMR Institute of Technology,2Principal, GMR Institute of Technology,3Professor & Associate Dean, Centurion University,5Asst.Professor in the Mechanical Engineering Department, GMR Institute of TechnologyABSTRACTWelded joints are used for construction of many structures. Welding is a joining orrepair process which induces high residual stress field, which combines with stressesresulting from in-service loads, strongly influencing in-service behavior of weldedcomponents. When compared with stresses due to service loads, tensile residual stressreduces crack initiation life, accelerates growth rate of pre-existing or service-induceddefects, and increases the susceptibility of structure to failure by fracture. Also, weldingresidual stresses are formed in a structure as a result of differential contractions which occuras the weld metal solidifies and cools to ambient temperature.Previously some of the methods like heat treatment and peening kind techniques wereused for reduction of residual stress. However, those methods need special equipment and aretime consuming. In this, we are proposing a new method for reduction of residual stress usingvibration during welding. For this Mechanical vibrations will be used as vibration load. Inthis work, Finite Element Method (FEM) will be used for assessment of welding residualstresses and comparison of experimental results with FEM results for Mild steel butt weldedjoints [2].INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERINGAND 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.comIJMET© I A E M E
  • 2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME543Keywords: Welding, Vibration, Residual stress, Finite element method.I. INTRODUCTIONWelding is widely used for construction of many structures. Since welding is aprocess using locally given heat, residual stress is generated near the bead. Residual stressesare defined as the stresses which remain within a structure when all external loads orreactions are removed, hence they must be self-balanced within the structure itself.It is well accepted that the residual stresses commonly arise from permanent changesin the shape of the body. The residual stresses generated during welding may hamper thefunctional efficiency of the component leading to failure of the engineering structures. It mayalso lead to brittle fracture of the welded structures causing enormous damage to resourcesand loss of human life.Residual stresses are the major constituents of a stress field around a crack whichmay lead to cracking. Tensile residual stresses reduce fatigue strength and corrosionresistance while compressive residual stresses diminish the stability limit. Also, while tensileresidual stresses may initiate the failure due to fracture, the compressive residual stresses neara weld can reduce the capacity of the structural member in buckling and collapsing.Some reduction methods of residual stress have been presented for example, heattreatment and shot peening techniques are used. However, those methods need specialequipment and are time consuming. In this, we are proposing a new method for reduction ofresidual stress using vibration during welding.II. PROBLEM DEFINITION1. 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. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME544III. EXPERIMENTAL SETUPReduction of residual stress on both sides of the specimen using vibrational load isexamined 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 bybolts as shown in fig.1. Specimens are vibrated by a vibromotor during welding specimensare butt-welded using an arc welding machine. In order to examine the effect on excitationfrequency on reduction residual stress amplitudes of excitation frequencies are chosen as70,80, 84 and 90Hz. The frequencies are measured by the vibrometer . Size and shape ofspecimen made of mild steel for general structure (mm) in fig 2.Fig.1 Supporting device for weldingFig. 2 Size and shape of specimen made of mild steel for general structureAfter completion of welding the specimens are taken to the multi channel strainindicator for measuring strains. In this method, therefore, strain gauges in the form of a threeelement rosette are placed in the area under consideration. A through-thickness hole isdrilled in the centre of the strain gauge rosette. In this way the residual stresses in the areasurrounding the drilled hole are relaxed and the relieved radial strains can be measured with asuitable multi channel strain gauge.
  • 4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME545Fig.3. The strain gauges are bonded to the specimensFig.2 Strains are measured by Multi Channel Strain Indicator shown inIV. CALCULATIONHole drilling Method: According to this popular and well established method residual stressis determined by measuring the relieved radial strain when drilling a small through-hole intothe weld plate. Two principal stressesV. OBSERVATIONSFrom the above experimental setup, through the multi channel strain indicator thefollowing are the observations of residual stresses values are shown in tables.
  • 5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME546Table 1. Residual stress values at different frequencies at first side perpendicular tothe beadTable 2. Residual stress values at different frequencies at first side parallel to the beadTable 3. Residual stress values at different frequencies at second side perpendicular to thebead
  • 6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME5471MNMXXYZ-.550E+09-.472E+09-.394E+09-.316E+09-.239E+09-.161E+09-.832E+08-.547E+07.723E+08.150E+09JUN 2 201214:01:14NODAL SOLUTIONSTEP=1SUB =3FREQ=84.2REAL ONLY/EXPANDEDSX (AVG)RSYS=0DMX =.319E-03SMN =-.550E+09SMX =.150E+09Table 4. Residual stress values at different frequencies at second side parallel to the beadVI. FINITE ELEMENT MODELThe welding process of a butt-weld joint of two IS2062 mild steel plates with thedimensions shown in Fig.1 was simulated. Due to high temperature and stress gradients nearthe weld, the finite element model has a relatively fine mesh in both sides of the weld centerline. The eight-node brick elements with linear shape functions are used in meshing themodel. To simulate the moving heat source it is necessary to model the heat source duringeach time increment. In this analysis the moving heat source is simplified by assuming thewelding arc stayed at an element with a constant specific volume heat generation, and thenmoved to the next element at the end of the load step as the welding was finished. Theelement type SOLID70, which has a single degree of freedom, was used for the thermalanalysis. For the structural analysis the element type SOLID45, with three translationaldegree of freedom at each node, was used. The geometry model is shown in fig 1 andTemperature distribution graph is shown in fig 2&3 and Residual stresses graph are shown in4&5.Fig.1 Geometry of the model used in the Fig 2. Temperature distribution first sideAnalysis of welding
  • 7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME548Fig.3. Temperature distribution second side Fig 4. Residual stresses at first sideof welding weldingFig 5. Residual stresses at second side weldingVII. RESULTS AND ANALYSISFrom the above observations tables the residual values are analyses and are shown ingraphsGraph.1. Residual stress values at different frequencies at first side perpendicular to the bead1MXXYZtemperature distribution after second side of welding27267.252507.504747.757988.00912281469170919492189MAY 21 201210:55:35NODAL SOLUTIONSTEP=1SUB =1TIME=40/EXPANDEDBFETEMP (AVG)RSYS=0DMX =.570E-03SMN =27SMX =21891MNMXXYZ-.570E+09-.486E+09-.402E+09-.317E+09-.233E+09-.149E+09-.648E+08.194E+08.104E+09.188E+09JUN 2 201212:27:23NODAL SOLUTIONSTEP=1SUB =1TIME=20/EXPANDEDSX (AVG)RSYS=0DMX =.337E-03SMN =-.570E+09SMX =.188E+091MNMXXYZ27207.74388.48569.22749.96930.71111129214731654APR 1 201222:52:22NODAL SOLUTIONSTEP=20SUB =1TIME=20/EXPANDEDTEMP (AVG)RSYS=0SMN =27SMX =1654
  • 8. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME549Graph.2. Residual stress values at different frequencies at first side parallel to the beadGraph.3. Residual stress values at different frequencies at second side perpendicular to thebeadGraph.4. Residual stress values at different frequencies at second side parallel to the bead
  • 9. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME550VIII. COMPARISON OF PRACTICAL AND ANSYS VALUESTaking the experimental and Analysis results are shown in below TablesTable 1. Residual stress values at different frequencies at first side perpendicular to the beadTable 2. Residual stress values at different frequencies at first side parallel to the beadTable 3. Residual stress values at different frequencies at second side perpendicular to thebead
  • 10. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME551Table 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 graphsGraph 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. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME552Graph. 3. Residual stress values at different frequencies at second side perpendicular to thebeadGraph.4. Residual stress values at different frequencies at second side parallel to the beadIX. CONCLUSION1. A new method for reduction of residual stresses vibrational load during welding isproposed. The proposed method is examined experimentally for some conditions. Two thinplates 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 of84Hz.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 andstructural analysis to find out the residual stresses.5. The residual stresses were found by using Finite Element software for mild steel IS2062 is118Mpa.6. Hence residual stresses can be greatly reduced by maintaining frequency of forcedvibration nearer to the natural frequency of the specimen.
  • 12. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME553X. REFERENCES[1]. Shigru Aoki and Tadashi Nishimura, “Reduction method for residual stress of weldedjoint using random vibration 235(2005) .[2] Shigru Aoki Tadashi Nishimura Tetsumaro Hiroi Seiji Hirai “Reduction method forresidual stresses weld joints using Harmonic vibrational load”, Nuclear Engineering design237(2007).[3]. LIYAJIALG and WANG JUAN, ”Finite element analysis of Residual stress in thewelded 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 Buttwelding 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 stressdue 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 aSUS304 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 residualstress development in welding of aluminium alloy 2024”, Received 10 June 2003; receivedin 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 toPredict 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 Vibrationusing 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.