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BITSPilaniPilani Campus
VINAYAK KALLURI
BITSPilaniPilani Campus
BITS Pilani, Pilani Campus
Welding
Welding is used for making permanent joints.
A weld is defined by the American Welding society
(AWS) as a localized fusion of materials or nonmetals
produced either by heating the materials to the required
welding temperatures with or without the application of
pressure, or by the application of pressure alone, and with
or without the use of filler materials
BITS Pilani, Pilani Campus
Classification of welding processes
Gas Solid StateArc Resistance Misc
Carbon arcMetal arcMIGTIGPlasma arcSubmerged arcElectro-slag
Oxy-acetyleneAir-acetyleneOxy-hydrogen
ButtSpotSeamProjectionPercussion
Friction
Ultrasonic
Diffusion
Explosive
Thermit
Electron-beam
Laser
Welding Process
BITS Pilani, Pilani Campus
MASTER CHART OF WELDING AND
ALLlED PROCESSES
BITS Pilani, Pilani Campus
Welding from automation point of view
0xyfuel gas welding (OFW) Shielded metal arc welding (SMAW)
BITS Pilani, Pilani Campus
Gas tungsten arc welding (GTAW) Gas metal arc welding (GMAW)
Welding from automation point of view
BITS Pilani, Pilani Campus
Welding -Fundamentals
BITS Pilani, Pilani Campus
Welding -Fundamentals
BITS Pilani, Pilani Campus
Welding -Fundamentals
BITS Pilani, Pilani Campus
Welded Joints
BITS Pilani, Pilani Campus
SPECIFICATION OF WELD SYSTEM
The AWS standard welding symbol
BITS Pilani, Pilani Campus
ARC AND GAS WELDING SYMBOLS
BITS Pilani, Pilani Campus
Fillet welds
(a) The number beside triangle indicates the leg size. The arrow
need to point only to one weld when the weld on all sides is
same.
(b) Here the weld symbol indicates that he weldment is
intermittent and staggered at 60 mm length at an interval of
200 mm (centre to centre distance).
BITS Pilani, Pilani Campus
Circle on the weld symbol indicates that the welding is to go
all around.
Fillet welds
BITS Pilani, Pilani Campus
Square butt welded on both
sides.
Single V with 60o bevel and
root opening of 2 mm
Double V Single bevel
Different groove preparations for butt joints
BITS Pilani, Pilani Campus
T joint for thick plates U and J joints for thick plates
Corner weld, meant
only for light loads
Edge weld for sheet metal
and light loads
Different groove preparations for fillet joints
BITS Pilani, Pilani Campus
Stress Analysis and Design of Welded Joints
Butt joint
Lap joint or Fillet joint
Parallel fillet joint (weldment parallel to the load)
Transverse fillet joint (weldment perpendicular to the load direction)
Shear welded joint
Both primary and secondary shear stresses act
Line weld concept is useful
Bending welded joint
Throat shear stress equal to 1/1.414 times the bending stress acts.
Line weld concept is useful
BITS Pilani, Pilani Campus
ANALYSIS OF BUTT JOINTS
/F hl = /F h l =
Typical butt joints with possible loading. Reinforcements, though can
increase the area taking the load, normally for fatigue loading induce
stress concentration at location like A and hence normally removed
by grinding or machining.
BITS Pilani, Pilani Campus
Typical transverse fillet weld
( ) ( )
sincos
2
135sin45sin
cos
sin
+=
=
=
=
hht
FF
FF
oo
n
s
B
C
D
BITS Pilani, Pilani Campus
The stresses at any angle in the weldment are
( ) ( )hl
F
hl
F
tl
F
A
F ss 2sincossinsincossin +
=+
===
( ) ( )hl
F
hl
F
tl
F
A
F nn cossincossincoscos 2 +
=+
===
( ) ( ) ( )[ ]222222 cossinsincossincos3' +++=+=hl
F
The resultant von-Mises stress is
( ) ( ) ( )
sincossincos
2
135sin45sin
cos
sin
+=
+=
=
=
=
ht
hht
FF
FF
oo
n
s
BITS Pilani, Pilani Campus
The stresses at any angle in the weldment are
hl
F
hl
F
hl
F
o
o
o
623.0
196.1
16.2'
,62.5at occurs stress Mises- vonmaximum The
5.62
5.62
5.62
'
max
0
=
=
==
=
=
=
BITS Pilani, Pilani Campus
Parallel Fillet Weld: Welding Code Method
/ 0 .707 1.414 /F hl F hl = =
( )
htFor
ht
707.0,45
sincos
0 ==
+=
BITS Pilani, Pilani Campus
Problem
The figure (b=d=50mm) shows a
horizontal steel bar of thickness h = 5
mm loaded in steady tension and welded
to a vertical support. Find the load F
that will cause an allowable shear stress
is 140 MPa in the throats of the welds.
BITS Pilani, Pilani Campus
Minimum Weld-Metal Properties
Table 93
BITS Pilani, Pilani Campus
Stresses Permitted by the AISC Code for Weld Metal
Table 94
BITS Pilani, Pilani Campus
aM = Fa
/V A =
/Mr J =
Primary shear stress:
Secondary shear stress:
Twisting moment:
[ ] ( )[ ] ++=+=
=
22
areas weldment theof cetroid about the
weldments theof area ofmoment polar Second
iiiyyxxiiGrAIIrAJ
J
i
SHEAR WELDED JOINT
BITS Pilani, Pilani Campus
An example of unequal weldments
2- weldmentof size leg
1- weldmentof size leg
707.0
707.0
2
1
22
11
=
=
=
=
h
h
hd
hb
btdtAAA 2121 +=+=
The total throat area against primary shear
Secondary shear estimation needs the estimation of the total
second polar moment of area of the two weldments together.
( ) ( ) ( ) ( )
( ) ( ) ( ) ( )1212
;12
;12
1212;
12;
123
2
3
2
22
3
2
2
3
2
2
3
1
3
1
11
3
1
1
3
1
1
2
1
btbtIIJ
btI
btI
dtdtIIJ
dtI
dtI
yxGyx
yxGyx
+=+===
+=+===
BITS Pilani, Pilani Campus
The centroid G can be
located as follows.
A
yAyAy
A
xAxAx
2211
2211
+=
+=
( )[ ] ( ) ( )[ ]( ) ( )222211
2
2
2
22
22
11
21
;
rAJrAJJ
yyxxryxxr
GG +++=
+=+=
An example of unequal weldments
BITS Pilani, Pilani Campus
The concept of line weldments
size throat unit weldfor area ofmoment polar Second
707.0
=
=
u
u
J
hJJ
dG 12/2/
0707.0 3dJ
dy
xhdA u =
=
==
The different patterns and their properties are listed in
Table 9-1.
BITS Pilani, Pilani Campus
Torsional Properties of Fillet Welds
(Table 9-1, page:484)
uhJJ 707.0=
BITS Pilani, Pilani Campus
Few torsion cases and equivalent line weldment diagrams
Note: check the orientation
BITS Pilani, Pilani Campus
A torque T=2 kN-m is applied to the weldment as shown.
Estimate the maximum shear stress in the weld.
Problem
BITS Pilani, Pilani Campus
A 20 mm thick steel bar is welded to a vertical support by
two fillet welds. Find the safe bending force F if the
permissible shear stress in the welds is 180 MPa.
Problem
BITS Pilani, Pilani Campus
BITS Pilani, Pilani Campus
BENDING WELDED JOINT
A
V=' stress,shear Primary
BITS Pilani, Pilani Campus
BENDING WELDED JOINT-Contd.
Secondary shear stress: A throat shear of is induced. where is the bending stress calculated by the following formula. In deriving
the formula the weldments have been treated as line welds and also the
distance between them is treated as simply equal to d, which is the
depth of the rectangular pattern.
bdh
M
hbd
Md
I
Mc
bdhhII
bdI
u
u
414.1
2/707.0
2/
2707.0707.0
2
2
2
2
===
==
=
BITS Pilani, Pilani Campus
Bending Properties of Fillet Welds
(Table 9-2; page:488-489)
uhII 707.0=
BITS Pilani, Pilani Campus
Bending Properties of Fillet Welds - contd.
(Table 9-2; page:488-489)
BITS Pilani, Pilani Campus
Few bending cases and equivalent line weldment diagrams
BITS Pilani, Pilani Campus
The Fig shows a welded steel bracket loaded by a static
force. Find the factor of safety if the allowable shear stress
in the weld throat is 120 MPa.
Problem
BITS Pilani, Pilani Campus
BITS Pilani, Pilani Campus
Welded Joint under Fatigue loading
The conventional methods will be used
In fatigue, the Gerber criterion is best; however, you
will find that the Goodman criterion is in common use.
For the surface factor, forged surface should always be
assumed for weldments unless a superior finish is
specified and obtained.
BITS Pilani, Pilani Campus
Fatigue Stress-Concentration Factors, Kfs
Table 95
BITS Pilani, Pilani Campus
The weldment is subjected to a completely reversed force F.
The hot rolled steel bar is 10 mm thick and is of AISI 1010
steel. The vertical support is of AISI 1010 steel. The
electrode is 6010. Estimate the completely reversed load F
the bar will carry.
Problem
BITS Pilani, Pilani Campus
kN 22.09Fa
) 0& 1n(For SFK
n
1KK
5)-9 (Table 2.7K
MPa 7.82S
0.59k
1k
0.656(427)272k
MPa 213.50.5SS
MPa 427S
4)-9 (table electrode For the
mm 721.14A
fseafs
f
fsafs
fs
se
c
b
-.995
a
ut
1
e
ut
2
=
====
=+
=
=
=
=
==
==
=
=
ma
ut
m
e
A
SS
BITS Pilani, Pilani Campus
kN 4.73F
SFK
(assume) 1K
MPa 4.721S
0.85k
1k
0.917(320)7.75k
MPa 1600.5SS
MPa 320S
20)-A (table 1010 AISI member, For the
a
seafs
fs
se
c
b
0.718-
a
ut
'
e
ut
=
==
=
=
=
=
==
==
=
Aa
kN. 22.09 values} two{abovemin F ==