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© Siemens AG 2012. All rights reserved.
E F PR SU R&D HP 3
Structural Mechanics
of Steam Turbines:
Facing Challenges in
FE-Postprocessing
with STARpost
Dr. Benjamin Kloss-Grote
Siemens Energy
Large Scale Steam Turbines R&D
Mülheim/Ruhr, Germany
© Siemens AG 2012. All rights reserved.
Page 2 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
Contents
1. Introduction
2. The Challenge
3. Existing Solutions in Abaqus
4. Siemens Energy’s Solution: STARpost
5. Summary
Page 3 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
1. Introduction
Boiler
HP + IP + LP Steam Turbines
Condenser
Generator
Coal Fired Steam Power Plant SPP
Page 4 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
1. Introduction
Siemens Steam Turbine SST5-6000 (900MW, H-I-L-Turboset)
Example:
total mass >1000 tons
rotor: 55 m long, 430 tons
HP: inlet 540°C (1000°F), 270 bar (3900psi)
IP: inlet 580°C (1080°F), 70 bar (1000psi)
LP: inlet 204°C (400°F), 4 bar (60psi)
power output: 900 MW
typical lifetime: 30 years
Page 5 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
Outer Casing (schematic)
1. Introduction
Topology of a Siemens Intermediate Pressure (IP) Turbine (schematic)
Example Steam Conditions:
Inner Casing
HP TurbineLP Turbines,
GeneratorRotor (schematic)
Exhaust: 204°C (400°F), 4 bar (60psi)
Inlet: 580°C (1080°F), 70 bar (1000psi)
Page 6 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
Contents
1. Introduction
2. The Challenge
3. Existing Solutions in Abaqus
4. Siemens Energy’s Solution: STARpost
5. Summary
Page 7 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
Non-Isothermal Assembly
(Loadcase: Steady State Operation)
! Material Strength( , , )( , , ) ( , , )existing allowable
allowable
x y zx y z x y z
SF
high
low
low
high
high
low
(2)
Legend:
2. The Challenge (I)
Strength Assessments in Isothermal vs. Non-isothermal Assemblies
Isothermal Assembly
(Loadcase: Pressure Test)
Existing
Stress (Mises)
! Material Strength( , , )existing allowable
allowable
x y z constSF
Strength
Assessment
SF: Safety Factor
(1)
Temperature
Material Strength Inhomogeneous temperature distribution
prevents classic stress based assessments
Page 8 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
2. The Challenge (I)
Solution I: New Field Output
! Material Strength( , , )( , , ) ( , , )existing allowable
allowable
x y zx y z x y z
SF
Equation 2 from slide 7:
divided by the material strength:
!( , , ) 1( , , )
Material Strength( , , )
existing
existing allowable
allowable
x y zMU x y z MU
x y z SF
(3)
…results in a new variable: the material utilization MU.
%502
1%25
200
50
allowableexistingMUMU
MPa
MPa
Example: Existing Mises stress: 50 MPa; material strength: 200 MPa, allowable safety factor: 2
!( , , ) 1( , , )
Material Strength( , , )
existing
existing allowable
allowable
x y zMU x y z MU
x y z SF
!( , , ) 1( , , )
Material Strength( , , )
existing
existing allowable
allowable
x y zMU x y z MU
x y z SF
!
%502
1%25
200
50
allowableexistingMUMU
MPa
MPa
Advantage:
The allowable MU is constant over the whole assembly even in non-isothermal
assemblies if the allowable safety factor is constant.
Constant limits are easy to display in field output contour plots
Page 9 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
2. The Challenge (II-VI)
More Challenges for Steam Turbine Mechanics
II. Material strength is in general not contained in .inp and .odb
(e.g. Creep Rupture Strength Rm,t,T)
III. Different materials; assemblies with more than one material
(tedious input; material association has to be identified)
IV. Many frames need to be evaluated
(process automation required)
V. Many different output variables necessary
(material utilization (MU) based on different stresses; also strains, multi-axiality
factors etc.)
VI. Varying allowable safety factors
(e.g. for creep range and non creep range)
Page 10 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
Contents
1. Introduction
2. The Challenge
3. Existing Solutions in Abaqus
4. Siemens Energy’s Solution: STARpost
5. Summary
Page 11 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
3. Existing Solutions in Abaqus
User Subroutine UVARM in the Light of the Challenges
Advantages +
Material utilizations can be calculated
during the solver process
Major Disadvantages –
a) No self-explanatory output variable
names significant confusion and
possible quality issues,
b) A solver run is required. If a user output
has not been requested before the solver
run and should be added afterwards to the
ODB
a new solver run is required.
Inconvenient for long lasting creep
calculations (t=several weeks).
c) Material handling is very tedious (input
of material properties, material association
identification)
= User subroutine (Abaqus/Standard) for the generation of element output
It is possible to calculate the
utilizations with UVARM,
although limitations regarding
effectiveness and possible
quality concerns apply.
Page 12 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
Contents
1. Introduction
2. The Challenge
3. Existing Solutions in Abaqus
4. Siemens Energy’s Solution: STARpost
5. Summary
Page 13 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
4. Siemens Energy’s Solution: STARpost
Structure of the Python Plug-Ins
Structure of STARpost, the
post processing suite
for static and creep analyses,
including relevant inputs and
outputs:
STARvisSTARvisEffective Visualization of
STARmech‘s user variablesSTARvisSTARvisEffective Visualization of
STARmech‘s user variables
STARmechSTARmechCalculation of strength
assessment output variables
Effective strength assessment
contour plots in Abaqus/CAE
STARpostSteam Turbine Analysis Routines Post Processing Suite
ODBODB
R&D-Materials
Dpt. material
files
R&D-Materials
Dpt. material
files
User
input
(GUI)
User
input
(GUI)
User
input
(GUI)
User
input
(GUI)
ODB
with added user variables
ODB
with added user variables
Page 14 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XX Material Name XXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
MF
MF
MF
MU
_M
is
MU
_M
ax
MU
_M
axP
MU
_M
inP
DM
UC
4. Siemens Energy’s Solution: STARpost
Screenshot of the STARmech GUI
Screenshot of the GUI of
the STARmech-Plug-In:
Requesting user field
outputs for an efficient
strength assessment
during post processing,
suitable for
• non-isothermal,
• multi-material,
• multi-frame,
• static and
• creep
analyses
Frames
Requesting Field Outputs
ODB, Materials
Page 15 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
MF
MF
MU_Mis_200k
MU_Max_200k
DMUC_200k
4. Siemens Energy’s Solution: STARpost
Screenshot of the STARpost GUI
Screenshot of the GUI of the
STARpost-Plug-In:
Effective visualization of the
user output variables
calculated by STARmech
Existing Field Outputs
Frames
STARvis
STARmech
STARvis presents each user
output variable in a unique,
predefined way
Page 17 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
4. Siemens Energy’s Solution: STARpost
Comparison between Mises Stress and Material Utilization (after creep)
STARpost user field output
Mises Material Utilization
(User01)
Mises Stress
Significant difference
in the distribution
Challenge met
successfully
high
low
high
low
Page 19 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
4. Siemens Energy’s Solution: STARpost
Excerpt from STARpost’s Advanced Field Outputs
Name Description
User10_TempZone
Temperature Zone
Ti: Intersection Temperature
Tallowed: Maximum allowed application temperature of the material
User11_Min(Rp/Rm) min (Yield Strength Rp0.2,T, Creep Rupture Strength Rm,t,T)
User05_DMUC Dominant Material Utilization Criterion of User02_MU_Max
red, prohibited range ( )
yellow, creep range ( )
blue, non creep range ( )
allowed
i allowed
i
if T T
if T T T
if T T
, , ,
, , ,
, , ,
yellow ( ), min( , )
red ( ), min( , )
blue ( ), min( , )
Mises
m t T p T
I
I
m t T p T
III
III
m t T p T
Mises if MU_maxR R
if MU_maxR R
if MU_maxR R
Page 20 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
4. Siemens Energy’s Solution: STARpost
Advanced Field Outputs: Differentiating between Temperature Zones
STARpost user field output
Tempzone (User10) Prohibited Temperature Range
Creep Range
Non Creep Range
Color Coding:
very handy for strength assessments,
because different criteria apply for the creep and the non creep range
Page 21 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
4. Siemens Energy’s Solution: STARpost
Advanced Field Outputs: Material Strength and DMUC
STARpost user field output
Material strength
(Minimum of Yield Stress and
Creep Rupture Stress, User11)
STARpost user field output
Dominant Material Utilization Criterion
(DMUC, User05)
Max. Principal MU dominates
Mises MU dominates
Min. Principal MU dominates
Color Coding DMUC:
very handy for plausibility checks
high
low
Page 22 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
Contents
1. Introduction
2. The Challenge
3. Existing Solutions in Abaqus
4. Siemens Energy’s Solution: STARpost
5. Summary
Page 23 May 2012 Siemens Energy
© Siemens AG 2012. All rights reserved.
Dr. B. Kloss-Grote SCC 2012
5. Summary
Challenge: In non-isothermal assemblies, the stress (or strain) cannot be used solely
for strength assessments, because the material strength varies over the assembly
Abaqus offers the UVARM subroutine, which has some disadvantages regarding the
ease of use
Siemens Energy has developed STARpost, a Python based plug-in for Abaqus/CAE
for efficient post processing of non-isothermal assemblies, especially for creep
calculations
STARpost is fully automated with an intuitive GUI
STARpost can effectively generate and visualize strength assessment field output
variables
Standard and advanced user variables enable a quick and quality assured strength
assessment
With Abaqus and STARpost, we can reduce the development time and enhance the
value we deliver for our customers
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