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Unrestricted © Siemens 2020 Where today meets tomorrow.
Realistic and customer
correlated test schedules
Unrestricted © Siemens 2020
2020.03.30Page 2 Siemens Digital Industries Software
Need for durability engineering
How to capitalize on these implications ?
Unrestricted © Siemens 2020
2020.03.30Page 3 Siemens Digital Industries Software
Need for durability engineering
How to capitalize on these implications ?
Unrestricted © Siemens 2020
2020.03.30Page 4 Siemens Digital Industries Software
Agenda
Loads and damage
Load characterization
Customer correlation
Accelerated testing and analysis
Customer application case
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2020.03.30Page 5 Siemens Digital Industries Software
Agenda
Loads and damage
Load characterization
Customer correlation
Accelerated testing and analysis
Customer application case
Unrestricted © Siemens 2020
2020.03.30Page 6 Siemens Digital Industries Software
Road A
How to understand fatigue content of loads ?
Comparison of two measurements
Road B
Time Time
Hard
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2020.03.30Page 7 Siemens Digital Industries Software
How to understand fatigue content of loads ?
Comparison of two measurements
Road A Road B
DamageDamage
Time Time
Easy ☺
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How to understand fatigue content of loads ?
Damage calculation
Damage
Fatigue life (= 1/Damage)
S-N curve for
CA loading
Loads
Failure
t, time
σ, F
Rainflow counting
→ Range, mean & cycles
Damage accumulation
𝑖=1
𝐼𝑛𝑖𝑁𝑖
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2020.03.30Page 9 Siemens Digital Industries Software
1E+00 1E+01 1E+02 1E+03 1E+04 1E+05 1E+06 1E+07 1E+08
What is an S-N curve ?
Characteristics
Infinite life
High cycle
fatigue(Elastic behavior)
Low cycle
fatigue(Plastic behavior)
Number of stress cycles to failure (N)
Str
ess a
mp
litu
de
(S
)
N1
S1
Sut
Se
Sy
Finite life
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2020.03.30Page 10 Siemens Digital Industries Software
How to understand fatigue content of loads ?
Endo (1968). Rainflow counting for variable loads
Tatsuo Endo*1925 1989
Rainflow counting
= technique to decompose a spectrum of varying, complex stress
into a set of simple stress reversals
0+ +=
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Rainflow counting
Time5
4
3
2
1
10
9
8
7
6
2. Look for closed loops
3. Accumulate nr. of loop cycles
in ‘From-To’ cells of table
= Rainflow-matrix
‘From’
load
level
‘To’ load level
6
7
8
9
10
1
2
3
4
5
54321 109876
8
7
8
4
3
4
2 2
5
Load history
1. Classification
into bins
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How to understand fatigue content of loads ?
Rainflow characteristics
Zero range
Zero mean
Compression
Tension
Standing
Hanging
90000
60000
40000
30000
20000
10000
0
t
t0
- mean
t0
+ mean
t
Larger amplitudes(more damage)
Larger amplitudes(more damage)
To
Fro
m
# Cycles
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Counting methods in fatigue analysis
Benefits
• Representations → easy to understand
• Ability for fatigue related data manipulation (editing, extrapolation, superposition)
• Easy way to compare data
• Simple counting algorithms
• Substantial reduction of data amount
Same counting result = Same fatigue potential
Counting
method
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How to understand fatigue content of loads ?
Palmgren (1924) – Miner (1945). Damage accumulation rule
Assume that, during the service life, we have
• 500 cycles of load type 1
(defined by mid-value and magnitude)
• 1000 cycles of load type 2
• and 10000 cycles of load type 3
the Palmgren-Miner rule states that failure occurs
when
with:
• ni = the number of actual applied load cycles
of type i
• Ni = the pertinent fatigue life for that specific
applied load cycle i
𝑖=1
𝐼𝑛𝑖𝑁𝑖
= 1
= 0.5 = 0.01 = 0
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How to understand fatigue content of loads ?
Rainflow → Range-pair → Damage → Cumulative damage
Range-pair (cycle count)
4 0.9 1000.0300.0100.030.010.03.01.0Cycle Count
184.1
11599.0
1000.0
2000.0
3000.0
4000.0
5000.0
6000.0
7000.0
8000.0
9000.0
10000.0
11000.0
[N]
File Channel Number of bins Lower Limit Upper Limit Unit Hysteresis Filter
D:\Program Files\LMS\TecWare 3.7SL1+\demo\general\nature.erfm FORCE_vert 64 -936.7174 10846.3457 [N] 1
Range Pair
Ra
ng
e
# Cycles
Cumulative damage
6 0 10010 20 30 40 50 60 70 80 90Cumulative Damage [100%=6.2541E-3]
184.1
11599.0
1000.0
2000.0
3000.0
4000.0
5000.0
6000.0
7000.0
8000.0
9000.0
10000.0
11000.0
[N]
File Channel Number of bins Lower Limit Upper Limit Unit Hysteresis Filter
D:\Program Files\LMS\TecWare 3.7SL1+\demo\general\nature.erfm FORCE_vert 64 -936.7174 10846.3457 [N] 1
Range Pair
Ra
ng
e
Pseudo-damage
Damage
accumulation
(Miner’s rule)
Range-pair (damage)
5 0.00000 0.006250.00050 0.00100 0.00150 0.00200 0.00250 0.00300 0.00350 0.00400 0.00450 0.00500 0.00550Damage
184.1
11599.0
1000.0
2000.0
3000.0
4000.0
5000.0
6000.0
7000.0
8000.0
9000.0
10000.0
11000.0
[N]
File Channel Number of bins Lower Limit Upper Limit Unit Hysteresis Filter
D:\Program Files\LMS\TecWare 3.7SL1+\demo\general\nature.erfm FORCE_vert 64 -936.7174 10846.3457 [N] 1
Range Pair
Ra
ng
e
Pseudo-damage
Take S-N curve
into account for
pseudo-damage
distribution
Axes rotating:
X-axis = Mean
Y-axis = Range
Folding:
No distinction
between
standing
/hanging cycles
Rainflow (range/mean)
3Mean
Ra
ng
e
Rainflow
1To
Fro
m
Rainflow (symmetric)
2To
Fro
m
Only ranges and
# cycles are kept.
Mean value is
ignored.
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How to understand fatigue content of loads ?
Comparison of two measurements
Road A Road B
DamageDamage
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How to understand fatigue content of loads ?
Scatter in loadings
Scenario: 6 measurements
One lap on same road
Same weather conditions
Six different drivers
Range-pair histograms (cycle count)
Six different load histories
Six different range-pair histograms
Six different damage values
Six different fatigue lifes
Damage histograms (cumulative damage)
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Agenda
Loads and damage
Load characterization
Customer correlation
Accelerated testing and analysis
Customer application case
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How to design realistic test schedule ?
Target setting, handling multiple events
Extr
apola
tion
Edit
Desig
n
1%
Worst customer case
Test track
Special test
Load cases Load histories Rainflow matrices Rainflow manipulation
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How to design realistic test schedule ?
Target setting, handling multiple events
65%
25%
10%
TARGET
1%
Worst customer case
Test track
Special test
Load cases
Supe
rpositio
n
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How to design realistic test schedule ?
Target setting – Extrapolation for longer duration
Single lap
(measured)
Simply multiplied x6
Six laps
(measured)
Extrapolated
xMultiplying
not sufficient!
Six laps ?
Similar to real
measurement !
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How to design realistic test schedule ?
Target setting – Extrapolation for longer duration
Original matrix
Extrapolated matrix
Parameterization
• Extrapolation factor (“number of laps”)
• Smoothing factor (“reliability of data”)
-4-2
02
4-4
-2
0
2
4
00.5
11.5
2re
l. H
äufig
keite
n
Compensate for scattering on:
Type of drivers, load data, component dimensions, material properties, ...
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How to design realistic test schedule ?
From target to test procedure
Track mixture
Target
Special test III
Special test II
Special test I
Test track D
Test track C
Test track B
Test track A
S cj · track j
Equal
damage !
Test schedule
3x 7x
6x 4x
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Target Result
How to design realistic test schedule ?
From target to test procedure using CombiTrack
Target
Result
Target
Nr. of track
repetitions
Target
damageDamage
per channel
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Agenda
Loads and damage
Load characterization
Customer correlation
Accelerated testing and analysis
Customer application case
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Customer correlation
Statistical approach Fleet measurement required
Siemens CuCo: Traditional RLDA + FleetTraditional customer correlation
Extensive
measurement
setup
(50+ channels)
Very limited
sample size
(1 car, few weeks)
Limited
customer
relevance !
Lean CuCo
measurement
setup (8 channels)
Extended
sample size
(Fleet: 5+ cars,
2-6 months)
High
customer
relevance !
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Customer correlation
Combined CuCo approach, ‘Traditional RLDA & fleet’
• Full RLDA (50-100 ch.)
on public roads
• One vehicle
• Limited time/mileage
Traditional RLDA
to capture
detailed load information
• Observation of
customer behavior
• Many customers/vehicles
• Extended accumulated
observation time/mileage
Fleet measurements
to capture
usage statistics
+
Detailed loading
per usage condition
Statistical frequency
of usage conditions
Usage space
Discretization (cells)
Pro
babili
ty d
ensity
Loading/Strength
Customer
usage
profile
Durability
test
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Customer
usage
profile
Durability
test
Pro
babili
ty d
ensity
Loading/Strength
Customer correlation
Result: “Fingerprint” of customer representative loading
“Fingerprint” of major vehicle loading components
Braking load (X)
1000
100
10
1
Acceleration load (X)Lateral load (y)
Vertical load (Z)
Low frequency
Vertical load (Z)
High frequency1% Customer EUR
Durability test
1% Customer new market
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Agenda
Loads and damage
Load characterization
Customer correlation
Accelerated testing and analysis
Customer application case
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2020.03.30Page 30 Siemens Digital Industries Software
How can you accelerate a test ?
1 Increase
speed
Increase
amplitude2 Omit non-
damaging events3 Simplify
the test4
Basic principle = conservation of damage
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How can you accelerate a test ?
Increase testing speed
1 Increase
speed
Increase
amplitude2 Omit non-
damaging events3 Simplify
the test4
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1st natural
frequency
How can you accelerate a test ?
Increase testing speed
Frequency content should stay reasonably below 1st natural frequency (resonances)
Important: Avoid too high compression !
27,4 s13,7 s
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How can you accelerate a test ?
Increase amplitude
1 Increase
speed
Increase
amplitude2 Omit non-
damaging events3 Simplify
the test4
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How can you accelerate a test ?
Increase amplitude
Logarithmic nature of fatigue
Changing slightly the cyclic load applied
to an optimally shaped steel component,
has a big influence on the life time of this
component
Load
Number of
cycles to failure
log
log
Life = (load)-k
1
k
+15% ÷2 !
Important:
Do not increase amplitude too much !
Yield
strength
Load (%) Number of cycles (%)
100 100
115 50
87 200
Be careful not to generate an uncharacteristic
failure mode (plastic vs. elastic).
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How can you accelerate a test ?
Omit non-damaging events
1 Increase
speed
Increase
amplitude2 Omit non-
damaging events3 Simplify
the test4
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How can you accelerate a test ?
Omit non-damaging events – Uni-axial
Acceleration of x14 !
100070
All cycles below 4000N only contribute
less than 0.5% of the total damage
If you remove these from the loading, you end
up with 70 cycles instead of 1000
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How can you accelerate a test ?
Omit non-damaging events – Multi-axial – RP-filtering
Vertical
Lateral
Longitudinal
Longitudinal
Uni-axial rainflow channel-per-channel is not OK
→ Phase relation lost !
Vertical
Lateral
Different loads !
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How can you accelerate a test ?
Omit non-damaging events – Multi-axial – RP-filtering
0 152 4 6 8 10 12 14Zeit [s] 1
-2000
3000
-1500
-1000-500
0500
1000
15002000
2500
FO
RC
E_
lon
g N
1
-3000
2000
-2500
-2000-1500
-1000-500
0
5001000
1500
FO
RC
E_
lat N
2
-2000
12000
-600
8002200
36005000
6400
78009200
10600
FO
RC
E_
ve
rt N
3
Attribute Name Unit
C:\Programme\LMS\TW 3.3 QC\demo\general\nature.dmd,FORCE_long NC:\Programme\LMS\TW 3.3 QC\demo\general\nature_edt.dmd,FORCE_long NC:\Programme\LMS\TW 3.3 QC\demo\general\nature.dmd,FORCE_lat NC:\Programme\LMS\TW 3.3 QC\demo\general\nature_edt.dmd,FORCE_lat NC:\Programme\LMS\TW 3.3 QC\demo\general\nature.dmd,FORCE_vert NC:\Programme\LMS\TW 3.3 QC\demo\general\nature_edt.dmd,FORCE_vert N
Small amplitudes/
little damage
Large amplitudes/
high damage
0.0 27.75.0 10.0 15.0 20.0 25.0Zeit [s] 1
-3510.1
3510.1
-3000.0
-2000.0
-1000.0
0.0
1000.0
2000.0
3000.0
FO
RC
E_lo
ng N
1
-2062.6
2062.6
-1500.0
-1000.0
-500.0
0.0
500.0
1000.0
1500.0
FO
RC
E_la
t N
2
-10509.7
10509.7
-7500.0
-5000.0
-2500.0
0.0
2500.0
5000.0
7500.0
FO
RC
E_vert
N3
Attribute Name Unit
C:\Programme\LMS\TW 3.3 QC\demo\general\nature.dmd,FORCE_long N
C:\Programme\LMS\TW 3.3 QC\demo\general\nature_edt_edt.dmd,FORCE_long NC:\Programme\LMS\TW 3.3 QC\demo\general\nature.dmd,FORCE_lat N
C:\Programme\LMS\TW 3.3 QC\demo\general\nature_edt_edt.dmd,FORCE_lat N
C:\Programme\LMS\TW 3.3 QC\demo\general\nature.dmd,FORCE_v ert NC:\Programme\LMS\TW 3.3 QC\demo\general\nature_edt_edt.dmd,FORCE_v ert N
Phase relation kept !
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How can you accelerate a test ?
Simplify the test
1 Increase
speed
Increase
amplitude2 Omit non-
damaging events3 Simplify
the test4
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How can you accelerate a test ?
Simplify the test – Constant amplitude test
Testing with
maximum
amplitude
4x more
damaging !10025
Accelerate by 4x
Increase sine wave
frequency ?28s 7s
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How can you accelerate a test ?
Simplify the test – Block cycle test
Mix of different ‘Constant-amplitude’ tests for more representative results
Original time series
Normal/incidental/accidental(automatic or user-defined)
Damage calculation(Standard S-N curve or user-defined)
Rainflow matrix
Block cycle test
Damage equivalent 3 36
12
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Agenda
Loads and damage
Load characterization
Customer correlation
Accelerated testing and analysis
Customer application case
Unrestricted © Siemens 2020
2020.03.30Page 43 Siemens Digital Industries Software
Accelerated durability tests for PVG and test rig
• Meeting 1.2 million km durability requirement
• Real tests would take 3 years ...
Large-scale customer data collection
• 5000 km Turkish public road data
• Ford Lommel proving ground
Target setting & Test schedule definition
Resulting in
▪ 6-8 week test track schedule
▪ 4 week accelerated rig test scenario
Test acceleration of factor 100
Application case Ford Otosan
Driving 1.2 million kilometers in 8 weeks
Siemens engineers performed dedicated data collection, applied extensive load data processing
techniques and developed a 6- to 8-week test track sequence and 4-week accelerated rig test
scenario that matched the fatigue damage generated by 1.2 million km of road driving.
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Application case Ford Otosan
Project steps
Validation
• PVG test
• 4-poster test of the cabin
• 4-poster virtual test
of the cabin
Test schedule
definition
• Data consolidation
• Data analysis
• Target for 1 Mio km
Goal
• 10.000 km PVG
Durability test
Data collection
• 4 months on Turkish roads
• 1 week proving ground
Preparation
Loads definition
• Target vehicle
• Current usage (full & empty)
Route selection
• 16 routes with 140 sections
in total
• = +/- 5.000 km
Instrumentation
• +/- 60 channels (acc., strain, displ.)
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2020.03.30Page 45 Siemens Digital Industries Software
Simcenter durability solutions throughout the development process
Unrestricted © Siemens 2020
2020.03.30Page 46 Siemens Digital Industries Software
Thank you!
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