Post on 25-Apr-2018
Web dynamics analysis, using finite element
simulations
Dominique KNITTEL, Prof.
knittel@unistra.fr
University of Strasbourg, FRANCE
2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Outline
1. Introduction & motivation
2. 1D Model : control synthesis
3. Web dynamics and finite element modeling
Model presentation
Results
4. Conclusion
2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL 2
Roll-to-Roll systems
3
• Large scale systems
• Multiphysics,
Mechatronics
• Manufacturing process
for common home
products and new
technologies
• Little waste, fast speed,
low cost production
Printed electronics Organic memories Paper printing Food packaging
Flexible solar panel printing system
Roll-to-Roll experimental plant
at Strasbourg
2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Common defects
4
• Strong coupling between
the different parts of the
system
• Lateral displacements
• Web properties
• Process involving
temperature, humidity,
chemical reaction
• Contact Web/rollers
• Roller shapes
Wrinkles in metal webs Wrinkles in polymer webs
Edge waves (baggy web)
2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Problem formulation : 1D modeling
Most models in roll-to-roll systems are one-dimensional (useful for controller adjusting/optimization):
Give the average tension in each web span and the velocity of each roller
Short simulation time
They do not take into account lateral or cross-machine effects
Assuming no slippage between web and roller
They are not able to predict/analyze web wrinkles
longitudinal web dynamics modeling : simulator in Matlab/Simulink
5
Cmotor1
T1+T2
2
T3+T4
2
Cmotor3 Cmotor5
Cfrictions1
Cfrictions5 Cfrictions3
E
R1
R3 R5 R2 R4
1 V1
V5
T1 T2 T3 T4
V3
…
5 10 15 20 25 30 35
0.5
1
1.5
2
2.5
3
Tension (daN)
T2
T1
Time (s)
0
2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Roll-to-Roll : control synthesis
Control : web tension, dancer position, web velocity, register
control, accumulator, ...
cascading control (torque, speed, web tension/dancer angle) measurements : dancer angle
control
6 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Roll-to-Roll : control synthesis
1D models : useful for the controller adjusting/optimization
Automatic synthesis of fixed order and structure controllers
(PID) :
- robustness to web elasticity variations
- effects of closed loop bandwidths
- master roller location ? (has also been studied)
Tension control (Ct : PI controller) or dancer position control
: automatically optimized with “robust control methodologies”
7 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Roll-to-Roll : automatic optimized control
synthesis
Global system subsystem
Controller CT is automatically optimized (Matlab)
M0 : desired closed loop model (fix the tension-loop bandwidth)
Wp, Wu, Wt : frequency filters
8 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Robust control : H∞ approach
9
in
2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Comparison: 1D models - 3D models
With the same controller: controller parameters calculated with
the 1D model
1D Model 3D Model
10 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Simulations : 1D and 3D models
Comparison 1D – 3D (in closed loop : with controllers) :
Co–simulation RecurDyn – Matlab/Simulink
11 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Simulations : 1D and 3D models
1D and 3D models:
1D model 3D model
Comparison 1D – 3D (in closed loop : with controllers):
web tension FEM Results- Lateral Stress and wrinkles
12
Cmotor1
T1+T2
2
T3+T4
2
Cmotor3 Cmotor5
Cfrictions1
Cfrictions5 Cfrictions3
E
R1
R3 R5 R2 R4
1 V1
V5
T1 T2 T3 T4
V3
…
2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
More complex processing lines have been
studied :
processing line with lateral guide : web stresses
13 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Model presentation : studied plant
- third roller is misaligned
- dynamics of the rollers and the web are taken into account
- the contact web/roller has to be modeled carefully
14 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Wrinkling prediction theory
15 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Critical angle of misalignment
from which wrinkling appears
Critical web tension from
which wrinkling appears
Lateral stress necessary to
overcome the friction force/
to create wrinkles
Results : simulation 1
- Tension: 400 N/m
- Misalignment angle: ~0 degree
- Friction ratio: 0.5
- Wrap angle: 90 degrees
- Web length/width ratio: 0.2
16
• Low average stresses value
• Uniformly distributed stresses
across the width
2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Results : simulation 2
- Tension: 400 N/m
- Misalignment angle: 0.5 degree
- Friction ratio: 0.5
- Wrap angle: 90 degrees
- Web length/width ratio: 0.2
17
• Low average stresses value
• Not uniformly distributed stresses
across the width
2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Results : simulation 3
- Tension: 700 N/m
- Misalignment angle: ~0 degree
- Friction ratio: 0.5
- Wrap angle: 90 degrees
- Web length/width ratio: 0.2
18
• medium average stresses value
• Uniformly distributed stresses
across the width
2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Results : simulation 4
- Tension: 700 N/m
- Misalignment angle: 0.5 degree
- Friction ratio: 0.5
- Wrap angle: 90 degrees
- Web length/width ratio: 0.2
19
• medium average stresses value
• High localized stresses (sign of
wrinkles)
• Not uniformly distributed stresses
across the width
2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Model presentation : studied plant
Plant at University of Strasbourg :
20 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Results
Comparison between 1D, 2.5D and 3D models :
21 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Results
Starting phase : velocity slippage roller 3 / web :
22 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Decoupling : results
Web tension in different web spans (3D model) : with or without decoupling :
Web tension decoupling : subsystem (i-1) -> subsystem (i)
and subsystem (i+1) -> subsystem (i)
23 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Roller deflection: results
Motor driven rollers
Idle rollers
In this study, we assume that one roller is flexible:
24 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Roller deflection: higher web stress
Friction = 0.5
With one flexible
roller
Without flexible roller
25 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Conclusion
The 1D model Advantages :
• Efficient and sufficient for a lot of applications
• Automated control synthesis
• Studies in the frequency domain
• Fast time simulations Drawbacks :
• Inaccurate web/roller contact
• Only longitudinal studies
The 3D model Advantages :
• Accurate web/roller contact
• Large possibility of studies: Complex phenomena such as wrinkles, edge waves, etc.
• Give us a lot of information about the web: state of stresses Drawbacks :
• Slow time simulations
• Need adequate tuning ( boundary conditions, elements, contact, algorithm)
26 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
Conclusion
27 2016 Aimcal Web Coating & Handling conference Europe D. KNITTEL
• All rollers should be aligned
• Reduce the web tension
• It is important to reduce as much as possible the web/roller friction coefficient
• The need of well tuned lateral guides (has to be aligned in steady state)
Other studies :
• Modeling, analysis and control of complex industrial roll-to-roll plants
(confidential works)
• Effects of other parameters : roller shapes, not uniform web thickness, not
uniform Young’s modulus, ....