The load carrying unit of articulated haulers

85 Pages·2009·6.01 MB·English

School of Technology and Design, TD

The load carrying unit of articulated haulers -
Analysis of the welded connections

Växjö June 2009
Thesis no: TD 068/2009
Nermin Dzanic
Martin Lindholm
Metin Uçar
School of Technology and Design
Organisation/ Organization Författare/Author(s)
School of Technology and Design Nermin Dzanic, Martin Lindholm and Metin Uçar

Dokumenttyp/Type of document Handledare/tutor Examinator/examiner
Master Thesis Torbjörn Ekevid Anders Karlsson

Titel och undertitel/Title and subtitle
The load carrying unit of articulated haulers - Analysis of the welded connections

Sammanfattning (på svenska)
Detta examensarbete handlar om finita element analys av svetsade förband i korgen på Volvo dumpern
A40E. Det genomfördes i samarbete med Volvo CE i Braås. Uppgiften var att ge företaget en lämplig
lösning för att minska mängden svetsskarvar på den främre delen av lastenheten. För att uppnå detta
har en rad analyser genomförts med hjälp av CATIA och ANSYS på både de befintliga och de
justerade (potentiella ersättare) svetsade förbanden. Analyserna visar att utmatningshållfastheten av
svetsade förband huvudsakligen beror på inbränningsdjupet. Med andra ord, förstärka svetsförband
genom större inbränning är mer fördelaktigt än att använda mer svets på utsidan. Slutsatsen blev att
både produktionstid och kostnad kan minskas genom justering av de svetsade förbanden. Eftersom
svetsförband på lastenheten är sammankopplade bör mer omfattande studier som inkluderar alla svetsar
genomföras för att uppskatta effekterna av liknande justeringar.

Nyckelord
Svetsade förband, svets, notch metoden, dumper, utmattning, Catia, Ansys, Volvo CE, Finita element metoden,
FEM, huvudspänning, 3-D modell, sub-model, mesh, simulering, analys, A40E
Abstract (in English)
The work presented in this master thesis is about the finite element analysis of the welded connections
in load carrying unit of the articulated hauler, Volvo A40E. It was performed in cooperation with
Volvo CE in Braås. The task was to provide the company with an appropriate solution to reduce the
amount of weld used on the front part of the load carrying unit. To accomplish this, a series of analyses
utilising CATIA and ANSYS was performed on both existing and adjusted (potential replacement)
welded connections. The analyses brought to light the fact that the fatigue resistance of welded
connections significantly depends on the penetration depth. In other words, reinforcing the welded
connections by deeper penetration is more beneficial than providing support from outside through
thicker weld. It was concluded that applying adjusted welds lessens both the production time and cost.
Nevertheless, since the welds on the load carrying unit are correlated; more extensive studies covering
all welds should be carried out to estimate the impacts of similar replacements.

Key Words
Welded connections, weld, notch method, articulated hauler, fatigue, Catia, Ansys, Volvo CE, Finite element
method, FEM, principal stress, 3-D model, sub-model, mesh, simulation, analysis, A40E
Utgivningsår/Year of issue Språk/Language Antal sidor/Number of pages
2009 English 75
Internet/WWW
II
Abstract
The work presented in this master thesis is about the finite element analysis of the welded
connections in load carrying unit of the articulated hauler, Volvo A40E. It was performed
in cooperation with Volvo CE in Braås.

The task was to provide the company with an appropriate solution to reduce the amount
of weld used on the front part of the load carrying unit. To accomplish this, a series of
analyses utilising CATIA and ANSYS was performed on both existing and adjusted
welded connections

The analyses indicate the fact that the fatigue resistance of welded connections
significantly depends on the penetration depth. In other words, reinforcing the welded
connections by deeper penetration is more beneficial than providing support from outside
through thicker weld.

It was concluded that applying adjusted welds lessens both the production time and cost.
Nevertheless, since the welds on the load carrying unit influence each other; more
extensive studies covering all welds should be carried out to estimate the impacts of
similar replacements.
III
Preface
The work presented in this master thesis concerns finite element analyses of the welded
connections in load carrying unit of the articulated hauler, Volvo A40E. It was performed
in cooperation with Volvo CE, at the Department of Mechanical Engineering at The
School of Technology and Design, Växjö University, between April and June 2009.

We would like to express our sincere thanks to our supervisor Prof. Torbjörn Ekevid,
Volvo CE and Växjö University, for initiating and excellently supervising the work. We
would also like to thank the engineers and managers at Volvo CE for assisting us
throughout the work.

Finally, thanks to Volvo CE for making possible to perform such an extensive work.

Växjö, June 2009

IV
Table of contents
Abstract ............................................................................................................................ III
Preface .............................................................................................................................. IV
Table of contents ............................................................................................................... V
List of figures ................................................................................................................ VIII
List of tables..................................................................................................................... IX
1. Introduction ............................................................................................................ 1
1.1. Background .......................................................................................................................... 1
1.2. Problem formulation ........................................................................................................... 1
1.3. Purpose and aim .................................................................................................................. 2
1.4. The outlines of the thesis ..................................................................................................... 2
1.5. Hypothesis ............................................................................................................................ 3
1.6. Limitations ........................................................................................................................... 3
1.7. Company presentation ........................................................................................................ 3
1.7.1. Volvo group ................................................................................................................. 3
1.7.2. Volvo CE Braås ............................................................................................................ 4
1.7.3. Volvo CE Braås history ................................................................................................ 4
1.8. Articulated haulers A40E ................................................................................................... 5
2. The welding process ............................................................................................... 6
2.1. Welding ................................................................................................................................ 6
2.2. Robot welding ...................................................................................................................... 7
2.3. Robot arc welding ................................................................................................................ 8
2.4. Weld dimensioning ............................................................................................................ 10
3. Fatigue calculations ............................................................................................. 12
3.1. Stress components ............................................................................................................. 12
V
3.2. Principal stress - eigenvalue approach ............................................................................ 13
3.3. Fatigue ................................................................................................................................ 14
3.4. Fatigue damage .................................................................................................................. 17
3.5. Effective notch stress ......................................................................................................... 18
4. Finite element method ......................................................................................... 20
4.1. One-dimensional analysis ................................................................................................. 21
4.2. Three-dimensional stress analysis .................................................................................... 24
5. Software ................................................................................................................ 27
5.1. ANSYS ................................................................................................................................ 27
5.2. CATIA ................................................................................................................................ 28
6. Method .................................................................................................................. 29
6.1. Preparing the 3-D models ................................................................................................. 30
6.2. Setting up the model for analysis in ANSYS ................................................................... 33
7. Results ................................................................................................................... 38
7.1. Existing welds .................................................................................................................... 41
7.2. Adjusted welds ................................................................................................................... 44
8. Analysis of the results .......................................................................................... 47
9. Discussion and conclusions ................................................................................. 50
10. Further studies ..................................................................................................... 51
11. References ............................................................................................................. 52
11.1. Books ......................................................................................................................... 52
11.2. Articles and theses .................................................................................................... 53
11.3. Electronic sources ..................................................................................................... 53
11.4. Company related sources ......................................................................................... 54
11.5. Pictures ...................................................................................................................... 55
VI
12. Bibliography ......................................................................................................... 56

Appendices Number of pages
Appendix A ..................................................................................................................................... 1
Appendix B ..................................................................................................................................... 1
Appendix C ..................................................................................................................................... 2
Appendix D ..................................................................................................................................... 3
Appendix E ..................................................................................................................................... 4
Appendix F ...................................................................................................................................... 1
Appendix G ..................................................................................................................................... 1
Appendix H ..................................................................................................................................... 6
VII
List of figures
Figure 1: Articulated Hauler A40 ........................................................................................ 5
Figure 2: Fully automate mechanized programmable tools ................................................. 8
Figure 3: Welding torch ....................................................................................................... 9
Figure 4: Wire feeder ........................................................................................................... 9
Figure 5: Weld, a- and s-measure ...................................................................................... 10
Figure 6: Weld, a- and i-measure ....................................................................................... 10
Figure 7: Weld affected area .............................................................................................. 11
Figure 8: Stress element for three-dimensional and two-dimensional (planar) case, ........ 12
Figure 9: Normal stress and shear stress ............................................................... 13
Figure 10: Example of S-N curve ...................................................................................... 15
𝜎𝜎𝜎𝜎 𝜏𝜏𝜎𝜎
Figure 11: Stress notations ................................................................................................. 16
Figure 12: Applying the radius of 1 mm on the weld root and weld toe ........................... 19
Figure 13: Continuous domain (left) and group of sub-domains (right) ........................... 21
Figure 14: An axially loaded member ............................................................................... 22
Figure 15: A portion of the member with the length of dx and its axial forces ................. 22
Figure 16 : A tetrahedral element in space defined by x, y, and z coordinates. ................ 24
Figure 17: Flowchart of the structural analysis by ANSYS .............................................. 28
Figure 18: Existing (left) and adjusted (right) welds ......................................................... 29
Figure 19: The gaps between the plates ............................................................................. 30
Figure 20: Closing the gaps by extending the plates ......................................................... 31
Figure 21: Connected plates, welds, notches, and radii ..................................................... 32
Figure 22: Weld specifications .......................................................................................... 32
Figure 23: Sliced basket for z direction ............................................................................. 33
Figure 24: Sliced load for z direction ................................................................................ 34
Figure 25: Sliced load and basket for z direction .............................................................. 35
Figure 26: Boundary conditions: flexible and cylindrical supports ................................... 36
Figure 27: The sub-model for z direction .......................................................................... 37
Figure 28: The highest maximum principal stress concentration areas ............................. 38
VIII
Figure 29: The hotspot for acceleration in z ...................................................................... 41
Figure 30: The hotspot for acceleration in y ...................................................................... 42
Figure 31: The hotspot for acceleration in x ...................................................................... 43
Figure 32: The hotspot for acceleration in z ...................................................................... 44
Figure 33: The hotspot for acceleration in y ...................................................................... 45
Figure 34: The hotspot for acceleration in x ...................................................................... 46
Figure 35: An example of existing welds indicating the penetration depth ...................... 48
Figure 36: An example of adjusted welds indicating the penetration depth ...................... 48

List of tables
Table 1: The absolute values of maximum and minimum principal stress ....................... 41
Table 2: The damages ........................................................................................................ 48
Table 3: The comparison of existing and adjusted welds .................................................. 50

IX
1. Introduction
This early section of the thesis work intends to provide a sound base for readers. The rationale
behind this study, the formulation of the problem, purpose and aim, and a brief description of
the company where the study was performed are presented.
1.1. Background
The heavy vehicle industry has been a rapidly growing industry for decades. This growth has
been achieved by continuous improvements in terms of products and services provided by
companies. Volvo Construction Equipment (CE) is one of the major companies in this field
and has made extensive contributions to this growth. Regardless of being the market leader,
Volvo CE continually makes investment in development activities in order to assure that its
products have the edge over its rivals. In addition to this, it aims to make sure of contentment
of its customers in all aspects, and reduce the expenditures of development, production,
maintenance etc.

This thesis work is a part of these development activities. It comprehensively covers
production and related phases suchlike development. The major effort will be put on a number
of particular welded connections, which are located on the front part of the load carrying unit.
1.2. Problem formulation
Volvo CE in Braås develops and manufactures heavy off road vehicles used to transport large
volumes of material in terrain difficult to enter. One of their main products is Volvo
articulated hauler A40E. Since the products constantly need to be improved due to both high
competitions in the market and customer contentment, the company requests help for
conducting analyses on the both existing and adjusted (potential replacement) welded
connections of the load carrying unit, i.e. basket. The outcomes of these analyses aim at
guiding the company to choose the best type of welded connections. The task is to provide
the company with an appropriate solution to reduce the amount of weld used to connect the
metal sheets that form the basket.
Authors: Nermin Dzanic, Martin Lindholm and Metin Uçar Page 1 of 56