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25/09/2014

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INNOVATIVE MATERIAL CONCEPTS FOR

HIGH VOLUME COMPOSITE APPLICATIONS

THE HIVOCOMP-PROJECT

IGNAAS VERPOEST, PROJECT COORDINATOR

COMPOSITE MATERIALS GROUP

KATHOLIEKE UNIVERSITEIT LEUVEN (BELGIUM)

Symposium on the occasion of the 5th anniversary of the Institute for Carbon Composites

TU Munich - 11 - 12 September 2014

COMPOSITE MATERIALS GROUP

@ KU LEUVEN

Composites on

macro- and meso-

level

Stepan Lomov

Composites on

micro- and nano-

level

Larissa Gorbatikh

Physical

chemistry of

composites

David Seveno

Natural and bio-

composites

Aart Van Vuure

Manufacturing

and application

development

Jan Ivens

coordinated by Stepan Lomov“backed-up” by em. prof. Ignaas Verpoest

5 ‘focus’ leaders5 junior postdocs24 PhD-students3 research engineers3 research affiliates4 visiting researchers4 technicians (pt)

~15 masters’ stud.

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THE COMPOSITE MATERIALS GROUP…

… in front of giant wallpainting by American artist Sol Lewitt at Museum M in Leuven

A HISTORY OF COLLABORATION

WITH PROF. KLAUS DRECHSLER

� 1986 (?): 1st meeting at ESTEC-conference, presenting the same ‘invention’: 3D-

fabrics!

� A continous string of joint European projects:

� 1990-1994: AFICOSS on sandwich panels based on 3D-fabrics

� 1996-1999: MULTEXCOMP on multiaxial textile preforms for complex structural

applications

� 2000-2004: TECABS on Technologies for Carbon fibre reinforced modular

Automotive Body Structures

� 2005-2008 : i-TOOL on Integrated Tool for Simulation of Textile Composites

� 2010-2014: HIVOCOMP on high volume composite applications

� Intensive not-formal collaboration around textile modelling, micro-CT and

permeability in the last three years (Ronald Hinterholz, Christoph Hahn, Jorg

Cichosz - Ilya Straumit and myself), several papers published/presented

� TUM participated in development of a new WiseTex version

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THE AFICOSS PROJECT !

Starting points for the HIVOCOMP-project

� Carbon fibre composites have the highest weight reduction

potential, but…

� Current applications of CFRP mostly in sectors

� where their use is principally not cost-driven

� which have limited production volumes, such as aerospace and

sports cars.

� For step-change in application of CFRP in larger-volume

applications,

� new materials systems are needed, combining

� very short production cycle times

� with performance that meets automotive requirements.

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Challenges of the HIVOCOMP project

� Cost reduction, both material ànd processing cost

� Cycle time reduction

� Consistent quality at higher volumes

� Meet specific performance requirements for automotive and

other high-performance, high-volume applications:

� increased toughness, even at low temperatures

� drastically improved damage tolerance

What HIVOCOMP intended to develop?

HIVOCOMP aims to achieve radical

advances in two materials:

� Advanced polyurethane (PU) thermoset

matrix materials offering a combination of:

� improved mechanical performance and

� reduced cycle times in comparison with

conventional matrix systems

� Thermoplastic PP- and PA6-based self-

reinforced polymer composites

incorporating continuous carbon fibre

reinforcements (“hybridisation”) offering:

� increased toughness and

� reduced cycle times in comparison to current

thermoplastic and thermoset solutions

Injectable Time

(until η >

300mPas)

Cure Time

(until η = 1E5

Pas)

(Definitions

used

in this work.)

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The global HIVOCOMP strategy…

… to be validated on 6 demonstrators !

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A leading academic and industrial partnership

coming together

� Project coordination:

� Project management

� Automotive partners

� Other part manufacturers

� Materials manufacturers

� University & research partners

THE PERT-DIAGRAM OF THE PROJECT…

� Add workpackage plan…?WP1: PU material

WP5: demonstrators

WP3: modelling

WP3: benchmarking & LCA

WP2: hybrid SRC

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WP1: DEVELOPMENT OF BREAKTHROUGH

PU MATRIX CHEMISTRY AND RESULTING

COMPOSITE MATERIALS

WHAT ARE THE BENEFITS OF SNAP CURE FOR

OPTIMAL PROCESSING?

Large Flexibility in Injectable Time

Very short ‘snap-cure’

maintained even with

longer Injectable Times

Normal thermosetting

behaviour shows an

increase in

cure time as the

injectable time is

increased.

Ideal tunable resin has

variable injectable time

and then a rapid cure

Injectable Time

(until η >

300mPas)

Cure Time

(until η = 1E5 Pas)

(Definitions used

in this work.)

Achieved by varying temperature and catalyst package

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WHAT ARE THE BENEFITS OF SNAP CURE FOR

OPTIMAL PROCESSING?

Large Flexibility in Injectable Time

Very short ‘snap-cure’

maintained even with

longer Injectable Times

Normal thermosetting

behaviour shows an

increase in

cure time as the

injectable time is

increased.

Ideal tunable resin has

variable injectable time

and then a rapid cure

Injectable Time

(until η >

300mPas)

Cure Time

(until η = 1E5 Pas)

(Definitions used

in this work.)

Snap cure + improved matrix properties

Unique high Tg

in combination

with good

toughness &

ductility

Low viscosity

in combination

with fast cure

kinetics

Partner Market Requirements

Modulus > 2.7 Gpa

Toughness G1c > 200 J/m2

Glass Transition > 210°C

Viscosity < 0.10 Pas at processing temp.

Cure Time < 3.0 min.

Property Unit Baseline- PU Formulation "B" Formulation " C"Flexural Strength [MPa] 119 126 133

Flexural Strain to failure [%] 8.8 9.3 9.0

Flexural E-modulus [GPa] 2.4 2.72 2.88

Tensile Strength [MPa] 51.9 58 79

Tensile Strain to failure [%] 2.8 - 3.2 2.6 - 2.8 4.8 - 5.4

Tensile E-modulus [GPa] 2.19 2.9 2.63

Fracture Toughness (Gic) [J/m2] 295 281 281

Tg (DMTA, E') [°C] ~ 256°C ~ 220° ~ 214°C

Cure time (Rheology)[min.]

~ 1.5 (@100°C) ~ 0.9 (@90°C) ~ 2.0 (@90°C)

~ 3.5 (@100°C) ~ 2.0 (@100°C) ~ 2.5 (@100°C)(DSC)

Reaction time (Rheology)[min.]

~ 3.5 (@100°) ~ 2.2 (@90°) ~ 1.5 (@90°)

Gel time (hot plate) - - -Pot life (@25°C water bath)

1 day - -

(100ml "semi-adiabatic") ~ 9.5 hour ~ 43 min. ~ 27 min.Viscosity (brookfield) @ 25°C

[mPa*s]

1280 268 302

@ 40°C 473 110 124

@ 90°C - 30 40

WP1- target

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RTM and VARI Processing

HP-RTM set-up

VARI set-up

PU FOR HP-RTM AND VARI PROCESSES

Equal Composite Properties, but …

significantly higher Tg

Mechanical properties of 0/90 or +/- 45 laminates

ILSS

tensile modulus

(+/-45)

3-pt Bend

(0/90)G1c

(kJ/m2)

Carbon fibre Avg panel ILSS ILSS Shear Shear Flexural Flexural

Vf thickness

90 in

centre 0 in centre Modulus Stress Modulus Strength

(%) (mm) (MPa) (MPa) (GPa) (MPa) (GPa) (MPa)

Formulation C~46 ~2.2 and 67,4 59 11,5 56,3 43,4 772,8 0,40

~4.3 3,8 6 0,3 1,1 2,7 50,1 0.02

Ref. tough

Epoxy

~47 ~2.1 and 64 57,6 11,9 60,6 47 851,6 0,37

~4.3 2,9 3,1 0,5 0,7 2,8 76,2 0,21

Comparison mechanical properties PU “C” – vs. Ref. (tough) epoxy-composite

Overall similar composite properties, but significantly higher Tg for PU “C” composite (> 200°C for PU-composite vs. < 120°C for epoxy-composite)

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WP2: HYBRID SELF REINFORCED

COMPOSITES

WP2

HYBRID SELF REINFORCED COMPOSITES

� The aim is to combine the properties of self reinforced polymers (PP

and PA):

� lightweight,

� outstanding impact

� can be produced at high volume…

with high stiffness carbon fibres to produce a composite material with an

optimum combination of toughness, stiffness and density.

� What is the trade-off in properties as carbon fibres are introduced ?

� Is there an optimum carbon fibre fraction?

Pure SRC (PP based - Curv®) is

currently used for a range of

non-structural applications

including Samsonite luggage and

Bauer Ice Hockey skates.

Samsonite

Cosmolite suitcase

Bauer Supreme

ONE.9 Ice Hockey

Skates Jr 2012

Nike Counter BPS

shinguard

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CONCEPT

Initial assembly

of oriented fibres

Under pressure, and at the

compaction temperature, surface

melting of the individual oriented

fibres occurs

As the assembly cools, the melted

material forms a matrix around oriented

fibres to bind the structure together

The Leeds

Hot compaction

process

Stiffening of CURV

composites without

loosing too much in

toughness

HYBRIDISATION CONCEPT:

CARBON FIBRE / SELF-REINFORCED PP or PA

100% SRC 100% carbon fibre

composite

Stiffness

Failure strain of brittle fibre

Strength

Toughness

Toughenening of CF-

PP-composites

without loosing too

much in stiffness

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The HIVOCOMP hybridisation strategy

WP2


� Three possible scenarios for hybridisation of carbon

fibres and oriented polymer fibres or tapes

Intra-layer

(co-weaving)

Intra-yarn

(co-mingling)

Interlayer

(Interlayer)

Carbon fibres and

oriented polymer

fibres mixed at the

yarn level.

Carbon fibre prepreg

co-woven with

oriented polymer tapes

Carbon fibre composite

sheets layered with

pure SRC

� Intra-layer and Intra-yarn show the greatest promise so far.

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INTRA- YARN HYBRIDISATION – PA BASED

Replace a fraction of the

polymer fibres with carbon

fibres

There are now less polymer fibres

to produce the matrix phase

What fraction of polymer fibres are required to

produce a well consolidated composite?

How do the mechanical properties of the

hybrid compare to a pure SRPC?

Hybrid

Single polymer

composite



• If the oriented PA12 fibres are completely melted (190°C) :

• the sample reverts to brittle behaviour (like ‘normal’ CF-PA

• the enhanced properties of the SRC fraction are lost. UD

Bending - Longitudinal

“ductile behaviour” of SRC is maintained @ 173°C

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Braided

25% carbon

13% carbon

� Braiding the hybrid yarns into a cloth (using

the facilities at the Technische Universität

München) allowed the hybrid SRC sheet

performance to be optimised.

� 13% carbon fibres gave a good balance

between stiffness and ductility in bending.

� Thermoforming trials using a simple

hemispherical mould showed that the

material can be thermoformed.

Hemisphere thermoformed at 160°C

13% carbon fibre/PA12 hybrid


INTRA- LAYER HYBRIDISATION – PP BASED

Intra-layer

(co-weaving)

Carbon fibre prepreg

co-woven with

oriented polymer tapes

� Co-weave oriented PP tapes and

carbon fibre/PP tapes.

� Initial studies on a hand loom and

follow up using a pilot scale large

loom at PROPEX FABRICS.

Woven cloth from a hand loom

Investigate the effect of carbon fibre fraction

by making cloths with a different separation

between the carbon fibre prepreg tapes.

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� The tensile properties (0/90 balanced laminates) show very

interesting results with different carbon fibre fractions.

8% carbon fibre fraction

[0/90]



� For 8% carbon fraction, the stiffness is

significantly increased, the failure

strain is unaffected while the impact

shows a drop, but still 3x value of

‘normal’ CF-PP.

� For the 15% carbon fraction, the

stiffness continues to increase, the

failure strain drops significantly, but

impact remains at same (high) level.

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Commercially woven hybrid inter-layer

cloth (8%) – PROPEX FABRICS

Thermoformed hemisphere – 8% carbon fraction

Thermoformed hemisphere – 15% carbon fraction

WP3 MATERIAL MODELLING AT

MICRO/MESO-LEVEL AND ADAPTATION OF

SIMULATION AND DESIGN TOOLS TO NEW

MATERIALS

3232

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INTERRELATION OF MODELS

Part impregnation 3.4 Spring-back Residual stresses

Macro-level

3.1

Residual stresses Local two-scale impregnation

meso-level

PU Hybrid -SRC

Chemistry of the resin Molecular structure of the

polymer

Hybridisation type (commingled yarns; intra-ply; interplay)

Textile interlacing architecture Parameters of the constituents of

the hybrid composite

Input from material development and optimization parameters

Process models

µicro -level 3.1 Reomechanics of cure Shrinkage

Formability 3.4 Spring-back Residual stresses

Macro-level

3.2

Deformability Impregnation Residual stresses

meso-level

µicro -level 3.2 Change of the polymer packing

state Shrinkage

Property models

3.4 Structural analysis of the part

Macro-level

µicro -meso -level 3.3 Micro-structural description of the

composite Stiffness Damage initiation and developm ent Strength Toughness

FEEDBACK FEEDBACK

PU Hybrid -SRC

3.1. MICRO-MESO PROCESS MODELS FOR NOVEL

PU RESIN (2)Meso-models for permeability of textile reinforceme nts

1.E-11

1.E-10

1.E-09

1.E-080.4 0.45 0.5 0.55 0.6

VF

K, m

2

Kx

Ky

calc

calc, Brinkmann

FlowTex software :

1. Stokes model (solid yarns)

2. Brinkmann model (permeable yarns)

3. Comparison with a benchmark exercise

Cure model integrated in PAM-RTM impregnation simul ation

Temperature at the end of the filling and curing simulations,

Injection from 6 ports at the sides, central exit.

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3.2 MICRO-MESO PROCESS MODEL FOR NOVEL

HYBRIDS AND SRCMicromechanics of unidirectional hybrids: strength

3.3 MESO-PROPERTY MODELS (PU AND SRC)Embedded elements method for textile composites

Yarn

Matrix

Validation on different scales :

micromeso

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WP 4Benchmarking and LCA/LCI

AIM OF THIS WORKPACKAGE

� Establish a materials property database for the materials developed in the

project, available for design of new parts.

� Select reference parts that will be used as demonstrators

� Establish a cost and environmental impact benchmark for the reference

components.

� Quantify how changes to material formulations affect cost and impact.

� Ensure that the material developments meet environmental and cost

requirements for automotive applications, from cradle to grave.

� Assess alternative design and guide for a new design

Impa

cts

and

cost

Current benchmark

HIVOCOMP

?

?

?

?

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� Costs & environmental impacts accumulate through the life cycle.� Life cycle approach� Quantify costs and impacts at each phase � Understand problematic areas

LIFE CYCLE COST / LIFE CYCLE ASSESSMENT

LCC&

LCA

End of Life

ManufacturingRaw

Materials

Use

Cost accumulation through stagesCost accumulation through stages

Environmental Burden accumulation through stagesEnvironmental Burden accumulation through stages

€ Redesign

Industrial viability

� Lifetime: 200 000 km

� End of Life:

� Recycling rates: 95% for steel and 90% for Aluminium and Magnesium to disposal

� Plastic & composite parts to incineration with energy recovery

WHY THE “RECYCLING GUIDELINE” OF THE

EU CAN BE CRITISED…

0% 20% 40% 60% 80% 100%

Passenger car

2t truck

4t truck

10t truck

Bus

Material production Parts & vehicle productionUse MaintenanceWaste Transport

� Only ~5% of the energy consumption during the life of a car is related to the “end

of life” (=waste), hence concentrating environmental policy exclusively on that

aspect is erroneous. The whole life cycle should be taken into account.

� Source: prof. Jun Takahashi, University of Tokyo

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PU VERSUS EPOXY COMPOSITES

� Cost and impacts for 1kg of processed composite with 50%CF,

for epoxy benchmark (Tg=120°C), formulation PU (B), PU (C)

and Epoxy High Tg (Tg=180°C).

80%

85%

90%

95%

100%

105%

(€) (DALY) (PDF*m2*yr) (kg CO2 eq) (MJ primary)

Cost Human health Ecosystem quality Climate change Resources

Epoxy high Tg

WP1 FormulationB

WP1 FormulationC

WP1 Epoxybaseline

MECHANICAL PROPERTIES

� Lightweighting potential demonstrated, compared to metals, from

materials developed in the project

0,5

1,5

2,5

3,5

4,5

5,5

6,5

7,5

8,5

1 10 100 1000

Den

sity

Young modulus (GPa)

PU(C) + CF

Epoxy + CF

Aluminium

Magnesium

PP hybrid 8% CF

PA12 hybrid 12% CF

Steel

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LIGHTWEIGHTING POTENTIAL-BENDING STIFFNESS

EQUIVALENCE

Density/E1/3 1.35 0.66 0.5 0.42 0.42 0.56 0.55

LIGHTWEIGHTING POTENTIAL

BENDING STIFFNESS EQUIVALENCE

0

5

10

15

20

25

0 100.000 200.000 300.000

Clim

ate

Cha

nge

(kg

CO

2 eq

.)

Lifetime distance (km)

Steel

Aluminium

Magnesium

Epoxy High Tg + CF

New material 1. PU(C) + CF

New material 2.a PP +CF

New material 2.b PA +CF

Epoxy High TG + GF

Climate change after processing and in service in a gasoline engine vehicle, for a part equivalent to 1kg steel part.

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LIGHTWEIGHTING POTENTIAL

BENDING STIFFNESS EQUIVALENCE

Climate change after processing and in service in a gasoline engine vehicle, for a part equivalent to 1kg steel part.

0

5

10

15

20

25

30

0 100.000 200.000 300.000

Clim

ate

Cha

nge

(kg

CO

2 eq

.)


Steel

Epoxy High Tg +CF

New material 1.PU (C) + CF

New material 2.aPP + CF

New material 2.bPA + CF

Epoxy High TG +GF

Steel "TECABS"

Steel "Uni Japan"

The ‘cross-over point ” between steel and CFRP strongly depends on the assumed initial CO 2-emission for producing 1 kg of steel..

LCA/LCC FOR OPTIMIZED PARTS OR

SCENARIOS

� Results from one Case study: VW B-Pillar, after 200 000km

� Scenarios:

1. High Tg Epoxy Benchmark / CF, weight=1kg

2. PU ( C) / CF, weight=1kg

3. Epoxy / GF, weight=1.27kg

4. Sandwich, Skin: PU ( C)/CF, Core: PU foam, weight=0.792kg

0%

20%

40%

60%

80%

100%

120%

140%

Cost (€) Human health(DALY)

Ecosystemquality

(PDF*m2*yr)

Climate change(kg CO2 eq.)

Resources (MJprimary)

S1: High Tg Epoxy/ Carbon fibers

S2: PU / Carbonfibers

S3: Epoxy / Glassfibers

S4: PU+CF skin &PU foam core

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SCENARIOS

� Case study: VW B-Pillar, 200 000km

� Sensitivity analysis: Carbon fibers impact, Data:

� Results with reference Scenario: PU ( C) / CF, weight=1kg

Climate change Resources

(kg CO2 eq) (MJ primary)

Carbon Fibres - standard production 53 1122

Carbon Fibres - green energy 31 704

Carbon Fibre - lignin precursor 24 670

Current LCA

LCA with green energy produced CF

LCA with lignin CF

600

700

800

900

1000

1100

1200

40 45 50 55 60 65

Res

ourc

es im

pact

(MJ

of p

rimar

y en

ergy

)

Climate change impact (kg CO2 eq.)

Case of study - B-pillar life cycle (200 000 km)


SCENARIOS

� New PU + different carbon fibers for a part equivalent to 1kg steel part

� The ‘cross-over point” between steel and CFRP strongly depends on the precursor

and energy source used for making the carbon fibres.

0

5

10

15

20

25

30

0 100.000 200.000 300.000

Clim

ate

Cha

nge

(kg

CO

2 eq

.)


Steel

New material 1. PU(C) + CF

Green energy CF +PU(C)

Lignin CF + PU(C)

Steel "Uni Japan"

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WP5: design and manufacturing of demonstrators

Demonstrators under development

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Real Demonstrator Parts (Volkswagen)

Innerbonnet

B-Pillar Reinforcement

• Full Composite B-Pillar (Golf A5)• Comparison to Metal/RTM• Critical Performance

• Side-Impact• Intrusion• Stiffness

• Innerbonnet Audi TT (A324)• Comparison to Aluminium/RTM• Complex Part • Highly ambitious Part

Real Demonstrator Parts (Daimler/CRF)

Front Crossbeam

Seat-back

• Front Crossbeam (Daimler)• Complex geometry• Comparison to Aluminium• Critical Performance

• Frontcrash• Intrusion• Stiffness

• Seat-back (CRF)• Comparison to Steel• SRC Part (PP and PA6)• Critical Performance

• Stiffness• Esthetic part

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Real Demonstrator Part (Samsonite)

Suitcase

• Samsonite Suitcase• SRC material (Curv )• Performance driver

• Toughness• Design Freedom• Stiffness

CONCLUSIONS

� Two new classes of materials have been succesfully

developed :

� An advanced PU resin combining tunable fast (“snap”) curing, low

viscosity and high Tg with good toughness.

� A class of hybrid self-reinforced thermoplastic composites (PP and

PA) combining drastically increased stiffness with high toughness

and fast processing

� Materials developed in the project have the potential

� to produce lighter weight parts

� that are still cost and environmentally effective

� provided that

� the design is well optimized

� the carbon fiber cost and impacts continue to decrease over the

coming years.

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The presented project results are realised by

this team:

� Project coordination:

� Project management

� Automotive partners

� Other part manufacturers

� Materials manufacturers

� University & research partners

B-PILLAR REINFORCEMENT

� Usage of PU to improve the crash behavior

� Further objective: Improvement of processing and weight reduction

� Design of two different parts (GFRP/CFRP)

� Design: ~80% (UD); ~20% (90°); Fibre Volume:~53%

� 3-Point Bending machine to test side crash behavior

Tool and GFRP partTest plates with CF and GF Testing Programm

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INNERBONNET

� Usage of PU to improve the crash behavior

� Further objective: Improvement of processing and weight red.

� Design: complex structure with (90°/35°/-35°/35°/90°)� Thickness: 1,1mm, Fibre Volume: ~55%

� Head Impact Testing for pedestrian safety

Tool and CFRP partCF Test plates for process monitoring

Testing Programm

FLOOR STRUCTURE

� PU resin instead of epoxy resin

� objective: Improvement of processing and weight reduction

� Design: Plybook with (+45°/-45°)� Thickness: 2mm, Fibre Volume: ~55%, Foam Core

� Pendulum Rig for testing (stone chip)

Tool and CFRP partCF Test plates for process monitoring

Testing Programm

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FRONT CROSS BEAM

� Weight reduction compared to aluminum components

� PU to reduce manufacturing costs and to improve the crash behavior

compared to epoxy

� Manufacturing of demonstrator parts via RTM process (closing plate)

and VAP process (inner shell)

� Low and high speed crash tests

FRP closing plate

FRP inner shell

Aluminum crash boxes

Low speed crash test(RCAR-Bumper)

High speed crash test(Euro-NCAP, 40% overlap)

CRASH BOX

� Investigations to analyze the influence of the resin

on specific energy absorption (crushing)

� Braided crash cones: 5 layers (triaxial) with braiding

angle of 67°-60°� VAP process to infiltrate test samples

� Crash tests: drop tower testing at Daimler

Braiding machine + preformTest plates with variation of infiltration temperature

Model of a triaxial braid

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SEAT PANEL

� Focus on SRC-Panel (PU as backup demonstator)

� Objective: improved crash behavior

� Further objective: Reduction of weight and surface resistance

� Design: CURV with 8% CF; stacking (0°/90°)� ESI simulations for tool design

� Static testing (overload of rotated rear seat)

Rear seat Panel Testing Programm

SUITCASE

� Focus on SRC (Cosmolite suitcase)

� Objective: Improvement of toughness/stiffness/design freedom

� Design: CURV with 8% and 15% CF; stacking 0°/90°/90°/0 °� Drop test on shell corners (Standard: 60cm,7kg, no dents)

� No significant difference in drop behaviour between CFPP and

conventional CURV

Forming Trials SRC-Part (15%) Test Results

CORNERDROP

15%CURV HACO 15%CURV HACO

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