Prediction of thermal conductivity and non-linear temperature-dependent mechanical behaviour of fiber reinforced composites for heat exchangers using Abaqus FEA

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Prediction of thermal conductivity and non-linear
temperature-dependent mechanical behavior of fiber
reinforced composites for heat exchangers using Abaqus
FEA
A.Krairi, X. W. Wang, J.Schalnat , W. Van Paepegem
Department of Materials, Textiles and Chemical Engineering (MaTCh),
Ghent University, Technologiepark 903, 9052 Zwijnaarde, Belgium,
e-mail: anouar.krairi@ugent.be
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Outline
The COMPOHEX project
Thermal conductivity
Non-linear mechanical behavior
• Pure polymer behavior
• SFRTPs behavior
Simulation at the structural level
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Strategic Basic Research (SBO)
Vlaio funding (Flemish government)
4 years of funding for research
institutes/universities
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COMPOHEX = COMPOsite Heat EXchangers
2016 2017 2018 2019
What is COMPOHEX Project?

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Why COMPOHEX Project?
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The heat exchanger market is estimated at about 500.000 tons per year in
the EU alone.
The corrosion is a major problem for heat exchangers,
Polymers and polymer based composites:
• Have a high corrosion resistance and very good chemical resistance,
• Easy to manufacture with low cost,
• Allow lighter structure compared to metals.
Impact of corrosion on metal heat exchangers

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Example of studied subcomponent
Cross-Corrugated heat-Exchanger
[Image from: Guo-Yan et al. 2014]
Example of manufacturing procedure
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Instrumented tensile tests are performed
at different temperature using climate
chamber and using Optical DIC
DMA tests are used to characterize the
material viscoelasticity
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0
200
400
600
800
1000
0 10 20 30
Force[N]
Strain [%]
Extensometer
DIC engineering
UGent composites group contribution
Experimental characterization
Validation of DIC results via Extensometer

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Homogenization step
FEM Analytical methods
Mean field homogenization
Multiscale approach
Macro-scale Meso-scale
UGent composites group contribution
Numerical simulation
SEM micrograph of tensile fracture surface of an
SCF/PP composite with 25 vol% carbon fibers.
(S.-Y. Fu et al. / Composites: Part A 31 (2000))
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Outline
The COMPOHEX project
Thermal conductivity
Non-linear mechanical behavior
• Pure polymer behavior
• SFRTPs behavior
Simulation at the structural level
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Prediction of the thermal conductivity
(Kumlutas and Tavman 2006)
Adiabatic
surfaceRVE
(Digimat FE)
Boundary conditions Result
(ABAQUS)
Finite element method (ABAQUS)
Mean field homogenization method
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Some factors affecting the TC
Filler volume fraction
Aspect ratio = length/diameter
Mixed inclusions with different shapes
Prediction of the thermal conductivity

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Effect of the filler volume fraction
Name Shape
Diameter
(mm)
Length
(mm)
Aspect
ratio
Thermal
conductivity
W/(mK)
Volume
fraction(%)
Orientation
Distribution
Matrix PP / / / / 0,14 [1]
Inclusion Carbon fiber Sphero-cylinder 0,0072 0,1 13,89 190 [2] Variable Random 2D
[1] CES Edupack 2016
[2] Karaipekli, Sarı et al. 2007
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Prediction of the thermal conductivity
Direction: out of plane
Direction: in plane

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Effect of the filler aspect ratio
Name Shape Diameter
(mm)
Length
(mm)
Aspect
ratio
Thermal
conductivity
W/(mK)
Volume
fraction(%)
Orientation
Distribution
Matrix PP / / / / 0,14 [1]
Inclusion Carbon fiber Sphero-
cylinder
0,0072 / Variable 190 [2] 15 Random 2D
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Prediction of the thermal conductivity
[1] CES Edupack 2016
[2] Karaipekli, Sarı et al. 2007
Direction: out of plane
Direction: in plane

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Effect of mixed inclusions with different shapes
Name Shape Diameter
(mm)
Length
(mm)
Aspect
ratio
Thermal
conductivity
W/(mK)
Volume
fraction(%)
Orientation
Distribution
Matrix PP / / / / 0,14 [1]
Inclusion
Carbon fiber Sphero-cylinder 0,0072 0,1 13,88 190 [2] 15 Random 2D
Carbon sphere Sphere 0,0072 / 1 190 [2] Variable Random 3D
Carbon fiber Carbon sphere
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Prediction of the thermal conductivity
[1] CES Edupack 2016
[2] Karaipekli, Sarı et al. 2007

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Effect of mixed inclusions with different shapes
Name Shape Diameter
(mm)
Length
(mm)
Aspect
ratio
Thermal
conductivity
W/(mK)
Volume
fraction(%)
Orientation
Distribution
Matrix PP / / / / 0,14 [1]
Inclusion
Carbon fiber Sphero-cylinder 0,0072 0,1 13,88 190 [2] 15 Random 2D
Carbon sphere Sphere 0,0072 / 1 190 [2] Variable Random 3D
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Prediction of the thermal conductivity
[1] CES Edupack 2016
[2] Karaipekli, Sarı et al. 2007
Direction: out of plane
Direction: in plane

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Outline
What is COMPOHEX project?
Thermal conductivity
Non-linear mechanical behavior
• Pure polymer behavior
• SFRTPs behavior
Simulation at the structural level
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The non-linear mechanical behavior of
short fiber reinforced polymers
Typical thermo-mechanical behavior
A behavior characterized by viscoelastic and viscoplastic deformations. It is
very sensitive to fibers orientations, the temperature and relative humidity.
Stress rate dependency of SGFRPA66 dry (DAM) and
stored at 50 % relative humidity (RH 50%) [Launay et al.,
2011a]
Effects of orientation and temperature of PA66 reinforced
by 30% GF [De Monte et al., 2010c]
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Outline
What is COMPOHEX project?
Thermal conductivity
Non-linear mechanical behavior
• Pure polymer behavior
• SFRTPs behavior
Simulation at the structural level
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New material behavior model for the polymer matrix is
proposed.
The model couples:
• Thermal effect
• Visco-elasticity
• Visco-plasticity
• Damage
Th-VE
Th-VE-VP Th-VE-VP-D
Pure polymer behavior

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Pure polymer behavior
3D printed PA12
Tensile tests at different strain rates, at RT
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Pure polymer behavior
3D printed PA12
Relaxation tests, at RT
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Relaxation tests at different level of maximum stresses

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Polypropylene (PP)
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[Exp data: Zhou and Mallick 2002a]
DMA test at different temperatures Tensile tests at different strain rates, temperatures
Pure polymer behavior
T=75 °C
T=50 °C
T=21.5 °C
̶ Calibration of the viscoelastic parameters using DMA tests

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Outline
What is COMPOHEX project?
Thermal conductivity
Non-linear mechanical behavior
• Pure polymer behavior
• SFRTPs behavior
Simulation at the structural level
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MFH of Th-VEVPD composites
• A linear comparison composite is employed
• Using incremental affine linearization method
MFH in Abaqus
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SFRTPs behavior

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Example of PA66 reinforced with Glass spheres at RT
• The material stiffness is well predicted,
• The predictions of the nonlinear behavior are overestimated. This a
known feature of the first order MFH methods.
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Matrix
Material:
PA66
Model: Th-VEVPD
Inclusion
Material:
Glass
Model: Elastic
E = 72 GPa ν = 0.3
Geometry: Spheres Ar = 1
Volume fraction: v 𝑓 = 15%
Behavior of Th-VEVPD composites

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Example of PA66 reinforced with Glass spheres at RT
The level of damage around the inclusion could be related to the initiation
of debonding between the matrix and the inclusions
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Loading rate ε= 0.5 1/𝑠
The damage field within the RVE varies between 0 and 1
Matrix
Material: PA66 Model: Th-VEVPD
Inclusion
Material: Glass Model: Elastic
E = 72 GPa ν = 0.3
Geometry: Spheres Ar = 1
Volume fraction: v 𝑓 = 15%
Behavior of Th-VEVPD composites

26. www.compohex.ugent.be
Outline
What is COMPOHEX project?
Thermal conductivity
Non-linear mechanical behavior
• Pure polymer behavior
• SFRTPs behavior
Simulation at the structural level
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Simulation at the structural level
Fiber Orientation and Volume fraction
RP
Temperature
distribution on pipe inner
surface
Pressure
distribution on pipe
inner surface
Pressure and Temperature
boundary conditions
Thermo-mechanical analysis
MF
Mean-fieldhomogenization
Material response
CFD simulation
Manufacturing simulation
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Discussion & Questions
Dr. Eng. Anouar KRAIRI, Postdoctoral researcher
-----------------------------------
Mechanics of Materials and Structures
Ghent University
Technologiepark-Zwijnaarde 903, 9052 Zwijnaarde
Belgium
Email: Anouar.Krairi@UGent.be
Tel : +32-(0)9 331 04 64
Mobile : +32-(0)4 7 336 336 7
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