2. Optimization of the capacitive gauges in terms
of testing and manufacturing procedures
17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
2
Mechanical Measurements Laboratory – Technological
Educational Institute of Piraeus
Konstantinos Velissaridis

3. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
3
Engineering Department
Mechanical & Materials Engineering Group
Mechanical Measurements Laboratory
Displacement
Transducers
Load-Tensile
Sensors
Vibration
Sensors
Strain gauges –
Optical /Resistive
Thermal Probes Calibration Tools
Properties measured : Force , stress, strain, displacement, vibrations, temperature, etc...
Environmental conditions : Magnetic fields, cryogenic temperatures, radiation
Introduction → MML
Static and Dynamic
Acquisition Systems
Post-Processing
and Analysis
Engineering Reports /
Conclusions
Preparation of the
Instrumentation

4. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
4
Introduction → CERN Internship
Projects assigned
Technical student in MML
Experimental
Stress
Analysis
LHC Diodes
Fresca 2
Sample Holder
Vibration
Measurements
ALICE Power
Converters
Experimental
modal analysis
Instrumentation of
magnet
prototypes
11 Tesla Fresca 2
Capacitive
gauges
optimization
Testing
sensors
R&D
sensors
EDMS
1263617
EDMS
1266838
EDMS
1275022
EDMS
1281142
EDMS
1246113
EDMS
1221318
EDMS
1318324
EDMS
1304901

5. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
5
Optimization plan
Testing
Set up
assessment
ISO Standard
Calibration
Mechanical
integration
EDMS Documentation – Bachelor thesis
New machine
validation
Manufacturing
Plastification of
the steel foils
Connection
alternatives
Implementation
of new ideas
My activities
Comparison with
baseline model

6. d0
Compression
forces Fc
17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
6
Introduction → Working principals
Based on the capacitance effect and the
principles of the elasticity of materials
𝑆𝑖𝑔𝑛𝑎𝑙 =
2 + 𝜔2
∗ 𝐶 𝑇 𝐹
2
∗ 𝑅2
4 + 𝜔2 ∗ 𝐶 𝑇 𝐹
2
∗ 𝑅2
−
2 + 𝜔2
∗ 𝐶 𝑇 𝐹=0
2
∗ 𝑅2
4 + 𝜔2 ∗ 𝐶 𝑇 𝐹=0
2
∗ 𝑅2

7. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
7
Introduction → Why capacitive gauges?
Load range: 0 to 200 MPa
Surface: According to applications
Thickness : 0.5 mm
Conditions: Cryogenic and magnetic field
Accuracy: < 5%
Others: Synchronized measurements with strain
gauges
Integrated surface
Average contact
stress measuring
Local uniaxial or
biaxial stress
monitoring

8. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
8
Optimization plan
Testing
Set up
assessment
ISO Standard
Calibration
Mechanical
integration
New machine
validation
Manufacturing
Plastification of
the steel foils
Connection
alternatives
Implementation
of new ideas
My activities
Comparison with
baseline model
EDMS Documentation – Bachelor thesis

9. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
9
Optimization → Machine Validation
• 400 KN
• Automatic control
• Insensitivity parasitic forces
• 200 KN
• Manual control
• High deformations
Hydraulic
Press
Load
Capacity
Control
Mechanical
Effects
Zwick Z400E

10. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
10
Optimization → Machine Validation
Conclusion
• Better accuracy and precision
• Homogenously distributed pressure
-500
-450
-400
-350
-300
-250
-200
-150
-100
-50
0
0 10 20 30 40 50
Signal(mV/V)
Force (KN)
Lab_Press
Z400E
x10-4
EDMS:1110695

11. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
11
Optimization plan
Testing
Set up
assessment
ISO Standard
Calibration
Mechanical
integration
New machine
validation
Manufacturing
Plastification of
the steel foils
Connection
alternatives
Implementation
of new ideas
My activities
Comparison with
baseline model
EDMS Documentation – Bachelor thesis

12. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
12
Optimization → ISO Calibration
Force ref
Resolution
Reproducibility
Repeatability
Zero Drift
Creep
Interpolation
Combined standard
uncertainty
𝒖 𝒄 =
𝒊=𝟏
𝟕
𝒖𝒊
𝟐
Experimental
Uncertainty
Assessment

13. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
13
Optimization → ISO Calibration
Force ref
Resolution
Reproducibility
Repeatability
Zero Drift
Creep
Interpolation
Combined standard
uncertainty
𝒖 𝒄 =
𝒊=𝟏
𝟕
𝒖𝒊
𝟐
Accuracy
Class 0.5
ISO 7500-1

14. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
14
Optimization → ISO Calibration
Force ref
Resolution
Reproducibility
Repeatability
Zero Drift
Creep
Interpolation
Combined standard
uncertainty
𝒖 𝒄 =
𝒊=𝟏
𝟕
𝒖𝒊
𝟐
0
0.02
0.04
0.06
0.08
0.1
0.12
0 50 100 150 200 250 300 350 400
Signal(mV/V)
Force Ref (KN)

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Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
15
Optimization → ISO Calibration
Force ref
Resolution
Reproducibility
Repeatability
Zero Drift
Creep
Interpolation
Combined standard
uncertainty
𝒖 𝒄 =
𝒊=𝟏
𝟕
𝒖𝒊
𝟐
Zero
Drift

16. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
16
Optimization → ISO Calibration
Force ref
Resolution
Reproducibility
Repeatability
Zero Drift
Creep
Interpolation
Combined standard
uncertainty
𝒖 𝒄 =
𝒊=𝟏
𝟕
𝒖𝒊
𝟐
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0 100 200 300 400
Signal(mV/V)
Force Ref (KN)
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0 100 200 300 400
Signal(mV/V)
Force Ref (KN)
3rd degree
1st degree

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Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
17
Optimization → ISO Calibration

18. 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
18
Optimization → Uncertainty contribution
Room
Temperature
Cryogenic
Temperature
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Contribution
Interpolation
Zero Drift
Creep
Resolution
Repeatability
Reproducibility
Force Ref

19. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
19
Optimization plan
Testing
Set up
assessment
ISO Standard
Calibration
Mechanical
integration
New machine
validation
Manufacturing
Plastification of
the steel foils
Connection
alternatives
Implementation
of new ideas
My activities
Comparison with
baseline model
EDMS Documentation – Bachelor thesis

20. Plot Legend
17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
20
Optimization → Manufacturing
Bonding: Two components adhesive
Application: Manual
Quantity: Random
Layer thickness: Uncontrollable
Energy dissipation → Hysteresis Glue plastification → Zero driftQuantity → Linearity
0
10
20
30
40
50
60
70
80
90
100
0 0.02 0.04 0.06 0.08 0.1 0.12
StressApplied(MPa)
Signal (mV/V)
Impact of the glue thickness

21. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
21
Optimization → Manufacturing
I. Initial signal step
↓
Lack of vacuum
II. Zero drift
↓
Atmospheric pressure
-0.35
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0 20 40 60 80 100 120 140 160 180 200
Signal(mV/V)
Force Ref (KN)
First results No Glue Glue

22. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
22
Optimization → Manufacturing
Continuous improvement of the model
Pros
• Simplified, faster and easier
manufacturing.
• Almost non existing hysteresis.
• Decreased thickness.
Cons
• Increased inactive surface.
• Vacuum + Hermetical sealing.
• Acceptable results but not matching
the best made baseline models.
Glue free model
Baseline model
-0.35
-0.28
-0.21
-0.14
-0.07
0
0 50 100 150 200
-0.35
-0.28
-0.21
-0.14
-0.07
0
0 50 100 150 200
-0.35
-0.28
-0.21
-0.14
-0.07
0
0 50 100 150 200
Signal(mV/V)
Stress (MPa)

23. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
23
Optimization → Manufacturing
0
2
4
6
8
10
12
0 20 40 60 80 100 120 140 160 180 200
CombinedRelativeUncertainty(%)
Stress (MPa)
Gauges' uncertainty comparison
New - RT
New - Cryo
Baseline - RT
Baseline - Cryo

24. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
24
Conclusions of my internship
• New machine integrated and validated
• ISO standard calibration procedure
implemented
• Promising new model with great potentials
Capacitive
gauges
• A great introduction to my engineering career
• Perfect learning experience
• Completion of my bachelor’s thesis and my
bachelor’s studies
Professional
• Traveling abroad for the first time
• Meeting and exchanging ideas with new
people
• Having the most memorable year of my life
Personal

25. 17/12/2013
Optimization of the capacitive gauges in
terms of testing and manufacturing
procedures
25
Special thanks to my Professor K. Nikas and my MML colleagues!
Thank you all for your attention!
Questions?