1) The document discusses residual stresses in welded plate girders through several studies that used welding simulation and experimental testing. Residual stresses were calculated, measured through sectioning, and compared to Eurocode methods. 2) One study presented experimental and simulation results on the fabrication of welded plate girders under workshop conditions to predict imperfections. Special focus was placed on the effects of residual welding stresses. 3) Another study incorporated welding simulation results directly into structural analysis models of large components to analyze their capacity while accounting for residual stresses. A simple example analyzed weak-axis buckling.

1. Summery
By- Tejaskriya

2. 01_Advanced residual stress assessment of plate
girders through welding simulation
• What to Find
• residual stresses are calculated and measured
by sectioning method.
• Also compared with Euro code method and it
shows that the approximate the result wrong.

3. IMP points
• premature yielding leading to a loss of
stiffness and a reduction in load-carrying
capacity (general influence of residual
stresses)

4. Questions
• Typical yield zone patterns of an I-shape
section at ultimate limit state (ULS) are
presented exemplary for pure compression
and 3-point bending in Figure 1.

5. 02_Welding of girders with thick plate
Fabrication, measurement and simulation
• What to find
• presents experimental and numerical results
of the fabrication of welded plate girders
under workshop conditions.
• prediction of imperfections with the aid of
simulation tools and/or simplified engineering
models.
• Special focus is put on the effect of residual
welding stress.

6. 03_Weld residual stress effects in the design of
welded plate girders, Simulation and Implementation
• What he Did
• in particular residual stresses, in large structural
components models was presented
• The hereupon based (simplified) welding
simulation as part of a subsequent structural
analysis is shown here.
• A novel numerical approach how to directly
incorporate the results into large structural
components models is presented.
• The capacity analysis is performed on a simple
example for weak-axis buckling.

7. Q
• Systems with coupled deformation and
strength characteristics, such as structural
components susceptible to global as well as
local instability modes, are negatively
influenced by the compressive residual
stresses.

8. IMP
• A very common approach is a model found in the
Swedish Design Code.
• In this, the maxima of the tensile residual stresses are
assumed equal to the yield strength of the base
material.
• Accordingly, high strength steel is being treated
conservatively [2], [6]. The width in tension, which
depends only on the plate thicknesses (valid only till
plate thicknesses of 40 mm) in this model, also defines
the value of the offsetting compressive residual
stresses.
• A thickness gradient as well as a stress reduction
towards the edges (especially for wide flanges [5]) are
not considered.
• Investigations on mild steel showed partly good, e.g.,
[5], but also partly unusable results, e.g., [6],
suggesting a more or less random match.

9. Models
Residual Stress Models
MECHANICALLY ANALOGEOUS MODELS
PROPOSED MODELLING

10. Residual Stress Models
1- EC 3, permit the use of non-linear finite
element analysis (FEA) for the design of
structures.
2- In this, the maxima of the tensile residual
stresses are assumed equal to the yield strength
of the base material.
3- high strength steel is being treated
conservatively

11. Not Done in residual stress method
1_A thickness gradient as well as a stress
reduction towards the edges (especially for wide
flanges [5]) are not considered.

12. MECHANICALLY ANALOGEOUS
MODELS
1) The starting point is to reduce the complex
thermo-mechanical problem to the pure
mechanical level (i.e. analogous forces, stresses
or strains).
2)This misfit may be interpreted as local
deformation or, as in the following, local
(inherent) strain. This is only produced in a
limited region near the weld.

13. 05_Effects of plate configurations on the weld
induced deformations and strength of fillet-welded
plates
What to find
1_access the importance of an accurate
prediction of the weld induced residual stresses
and distortion based on numerical simulations
and experiments
2_investigate the compressive longitudinal
ultimate strength of fillet-welded steel-
plated ship structures.

14. The Paper has 6 parts
1. Introduction
2. Welding experiments
3. Numerical simulation
4. Temperatures, distortions and residual
stresses
5. Ultimate strength of stiffened plate under
uniaxial load
6. Conclusiom

15. Part2_Experiments
1_single-pass fillet welding
2_K-type Agilent 34307A thermocouple wires
for_measure the temperature histories of the plate
specimens during the welding process.
3_To investigate the temperature distribution, 8 points
were selected for the measurements. As shown in Figs.
1 and 3 points with 15, 25 and 35 mm away from the
weld centreline, respectively, were selected on each
side of the top surface of the plates. There were 2
more points on both sides of the stiffener locating at
25 mm above the plate surface. Agilent 34970A data
acquisition/switch unit (see Fig. 2) were used to record
the temperature data of the selected points.

16. K-type Agilent
34307A

17. Part3_Numerical simulation
Heat source model
Heat flux
semi-ellipsoid located in
front of the welding X > 0
semi-ellipsoid located in
back of the welding X < 0 af+ar=2
a
b

18. Part3_semi-ellipsoid located in front of the welding X > 0
(x,y,z) are the coordinates in the local
coordinate system, a, b and cf are geometric
parameters, as shown in (slide 16 fig) , ff is
the heat input proportion in the front part.
a, b and cr are geometric parameters

19. Part3_semi-ellipsoid located in back of the welding X < 0
a, b and cr are geometric parameters, fr is the
heat input proportion in the rear part, and
ff + fr = 2

20. Part3_VALUES IN PRESENT SIMULATIONS
a =b 1= cf =4 mm
cr =16 mm.
ff= 0.4………………..(i.e temp in front is leading)
fr=1.6

21. Q
To consider the effect of the short interval
between the two welding passes, the heat input
in the 1st pass was removed in the
following times steps before being applied to
the nodes representing the FZ in the 2nd pass.
That means, in the interval without
any heat input, only the temperature in each
node in the previous time stepis considered as
the initial condition of the next step. (pg5 , 3.1)

22. specimens details

23. Part3_Material properties
Stiffened Plate SM400A shipbuilding steel
Choosing from (Prediction of welding distortion and residual stress in a thin plate butt-
welded joint)---(https://doi.org/10.1016/j.commatsci.2007.12.006)
Chemical Composition (Mass %) of SM400A shipbuilding steel
Thermal Properties
Mechanical PropertiesTemperature Dependent
C Si Mn P S
0.23 ------------ 0.56 < 0.035 < 0.035

24. Part3_Material properties
As per (Prediction of welding distortion and residual stress in a thin plate butt-welded
joint)---(https://doi.org/10.1016/j.commatsci.2007.12.006)
temperature
specific heat
&
coefficient of thermal
expansion
yield strength, modulus of
elasticity
thermal conductivity

25. Part3_Material properties
The liquidus temperature 1440 C has been
considered in the definition of thermal conductivity
and specific heat.

26. Part3_Material properties
The heat exchange between the welded plate and its
surroundings during welding and subsequently
cooling takes place by both convection and radiation.
It can be modelled by defining the convection
coefficient h = 15 W/m2/K, emissivity ε =0.9 and the
Stefan-Boltzmann constant = 5.67 * 10^(-8)
W/m2/K4 in an ambient temperature of 25 C.
Source- (Effects of different restraints on the weld-induced residual deformations and stresses in
a steel plate)_https://doi.org/10.1007/s00170-013-5521-9 (pg 4 & 5, 3.1.1)
These thermal boundary conditions are applied for all surfaces of the welding plate except for the symmetrical plane of
the plate.

27. Part3_Numerical approach based
on welding simulation
1_The FEA of the welding process can be
defined as 3D coupled TEP analysis.
2_Effect of the structural result on the thermal
analysis is not considered in the present study.
3_To perform the thermal and structural
analysis separately, an indirect method is
adopted to solve the single directional coupled
problem.
4_Fig illustrates the 3-step procedure of the TEP
approach to predict the ultimate strength of

29. Part3_3 step approach
Step 1
temperature histories of all nodes being firstly
calculated from the thermal analysis
Step 2
temperature histories of all nodes are used as body
loads into the some geometric model to complete the
mechanical analysis
Step 3
ultimate strength of the structure is calculated
considering the welding induced geometrical
deflection and residual stress obtained in the step 2
analysis

30. Part4_Temperatures, distortions
and residual stresses
Thermal analyses
1_3D finite element model is solved using ANSYS® code.

33. • fine mesh is required along the plate thickness