DIGIMAT FOR CONTINUOUS FIBER REINFORCED COMPOSITES · DIGIMAT FOR CONTINUOUS FIBER REINFORCED COMPOSITES The Challenge Continuous fiber reinforced composites in automotive industry

DIGIMAT FOR CONTINUOUS FIBER REINFORCED COMPOSITES

Roger Assaker, Pierre-Paul Jeunechamps, Jan Seyfarth, Laurent Adam

May 2011

DIGIMAT FOR CONTINUOUS FIBER

REINFORCED COMPOSITES

The Challenge

Continuous fiber reinforced composites in automotive industry

Synergy between different industries

Simulation technology for Continuous fiber reinforced composites

e-Xstream engineering

DIGIMAT Software

Application example: Wind Turbine Rotor Blade

Simulation Approach

Model

Materials

Results

Summary

Thursday, May 26, 2011 Copyright© e-Xstream engineering, 2011 2

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Continuous fiber reinforced composites in automotive industry

Glass fiber reinforcement (GFRP)

Carbon fiber reinforcement (CFRP)

• PROS

– Strong, stiff and light

• CONS

– High material costs

– Long manufacturing cycle times

Some applications already exist (sports cars, formula 1)

Not yet used in mass production vehicles

Seen as the technology for the future...

The Challenge


Continuous fiber reinforced composites in automotive

High-end sports cars

The Challenge Sources:

www.cardesignonline.com

www.rumors.automobilemag.com

www.wot.motortrend.com

Mercedes-Mclaren SLR Lamborghini Aventador



Future technology - CFRP passenger compartment

The Challenge

BMW i3 @ JEC Composites 2011

BMW i3 / BMW i8 Hybrid concept car

Sources:

www.bmw-i.de

www.wardsauto.com

www.treehugger.com



First approaches towards mass production

• Production facility in Landshut, Germany

– Serves as both a laboratory and pilot plant

– Houses what BMW calls "the world's first highly automated production process for CFP body components."

• 1.400 roofs produced for the M3 CSL coupe in 2003

• Increasing demand can bring price down to some acceptable level

– BMW and VW fight over SGL Carbon

– Access to carbon fiber ressources is critical

The Challenge Source:

www.findarticles.com:

„Can Carbon fibers compete?“


Investigation of design concepts


• Run on Carbon fiber material is ongoing

– Strongly growing market in automotive

– Strongly growing market in renewable energy

The Challenge www.zoltek.com


Investigation of design concepts


Automotive

• Mass production needed

• Cycle times & costs critical

• Strong focus on carbon fibers

Aerospace

• Automated production

• Cycle times not critical

• Glass & Carbon fibers

Renewable energy

• Automated & manual production

• Cycle times not critical

• Mainly glass fibers

The Challenge


Simulation is key to the investigation of future designs

For all of these industries there is a lack of sufficient material models to describe composites

• This is especially true for the demands from the automotive industry

• Material modeling must cover

– Different matrix properties

» Nonlinear effects

» Temperature dependency

» Strain rate dependency

– Different fiber properties

» Isotropic as well as transversely isotropic

» Anisotropy

– Failure

» Complex failure

» Fatigue failure

DIGIMAT Technology

e-Xstream engineering

Founded in 2003

The Business:

Simulation Software & Services

100% focused on material modeling

The team

Strong & highly motivated

High level of education

The product


Louvain-la-Neuve

Bascharage

Munich

Belgium

Luxembourg

Germany

U.S.

DIGIMAT Technology


DIGIMAT

DIGIMAT Technology


DIGIMAT Technology

Material modeling

Setup the material model


DIGIMAT Technology

Material modeling

Reverse Engineer material parameters


Interface to Drapage simulation

DIGIMAT Technology


Coupled solution

DIGIMAT Technology

Drapage(4.2.1/4.3.1)

FEA

http://www.altair.com/

http://www.esi-group.com/

http://www.samtech.com/


Multi-scale Simulation

DIGIMAT Technology


Wind turbine rotor blade

Virtual design of a wind turbine rotor blade

Check the performance of (expensive) carbon fibers in the virtual environment

• Compare to the existing design based on glass fiber material

Strategy

• Go from draping to FEA in a simple workflow

• Use one unique approach for the modeling of different composites

– Epoxy / Glass fiber

– Epoxy / Carbon fiber

• Define & use failure indicators on the microscopic level

– Max. Principle Stress in the fiber phase

– Max. Principle Strain in the matrix phase

Application Example


Model

Boundary conditions:

• The blade is fixed in displacement and rotation on the end where the blade is in real connected to the engine’s rotor

• A pressure is uniformly applied on one side of the blade, in the opposite direction to acceleration’s direction

Loading: +Z linear acceleration applied on the blade

Application Example


Application Example

Model

Shell sections

• 8 layers

• UD composite

Composite properties exchanged by DIGIMAT

material


Application Example

Model

Shell sections

• 18 layers

• 3 different materials

– Paint

– UD composite

– Foam

Composite properties exchanged by DIGIMAT

material


Application Example

Epoxy matrix (Isotropic)

Density 1100.0 kg/m^3

E 3300 MPa

PR 0.3

VF 0.4

Max Principal Strain (tens.) 5 %

Max Principal Strain (comp.) 10 %

Glass fibers (Isotropic)


E 72000 MPa

PR 0.22

VF 0.6

AR 10000

Max Principal Stress (tens.) 1500 MPa

Max Principal Stress (comp.) 700 MPa

Materials

UD composite / DIGIMAT model 1

• Glass fiber reinforcement


Application Example



E 3300 MPa

PR 0.3

VF 0.4



Carbon T300 fibers (Isotropic)


E 233000 MPa

PR 0.2

VF 0.6

AR 10000



Materials


• Carbon fiber reinforcement



E 3300 MPa

PR 0.3

VF 0.4



Carbon T300 fibers (Transversely isotropic)


Axial E 233000 MPa

In-plane E 23100 MPa

In-plane PR 0.2

Transverse PR 0.2

Transverse shear 8963 MPa

VF 0.6

AR 10000




Application Example

Materials


• Carbon fiber reinforcement


Failure analysis in Digimat-MF

Principle behavior of failure in a RVE

• No significant difference between isotropic and transversely isotropic carbon fibers models

• Matrix begins to break for lower values of j for glass fibers: 30° vs. 50° for carbon fibers

• Values of failure are much higher for Carbon fibers

Application Example

Loading direction

j

Max. Princ. Stress in Fibers

Max. Princ. Strain in Matrix


Result: von Mises stress

In the Epoxy phase

Application Example

Layer 31

Min. 0 MPa

Max. 72 MPa(iso.)

Glass fibers(iso.)

Layer 31

Min. 0 MPa

Max. 26 MPa(iso.)

25 MPa(trans.)

Carbon fibers(iso.)



In the Fiber phase

Application Example

Layer 33

Min. 0 MPa

Max. 674 MPa(iso.)

Glass fibers(iso.)

Layer 33

Min. 0 MPa

Max. 744 MPa(iso.)

793 MPa(trans.)

Carbon fibers(iso.)


The value in the epoxy matrix is much more significant when using Glass fibers

Danger of plasticity to occur in matrix

• Max. v.M. stress in epoxy matrix with Glass fibers 71 MPa

• Max. v.M. stress in epoxy matrix with Carbon fibers 25 MPa

To be on the save side, for glass fiber reinforcement nonlinear elastoplastic modeling of the epoxy matrix can be performed with DIGIMAT


Application Example

Result: Failure indicators (maximum values)

Highest values are found

• In the epoxy matrix under tension

• In the fiber phase under compression

Values are

• Critical for glass fibers under compression

• In general much lower for carbon fibers


Isotropic Glass

fibers Isotropic Carbon

fibers Transversely isotropic

Carbon fibers FI value Layer nr FI value Layer nr FI value Layer nr Max Epoxy tensile FI 0.408 31 0.148 31 0.129 31

Max Epoxy compression FI 0.182 31 0.057 31 0.075 3

Max fibers tensile FI 0.438 33 0.368 33 0.394 33

Max fibers compression FI 0.835 33 0.435 33 0.593 1

Application Example


Result: Maximum Principle Strain failure (tension)

In the Epoxy phase

Application Example

Layer 31(iso.)

fmax=0.408

Glass fibers(iso.)

Layer 31(iso.)

fmax=0.129

Carbon fibers(iso.)


Result: Maximum Principle Stress failure (compression)

In the Fiber phase

Application Example

Layer 33(iso.)

fmax=0.835

Glass fibers(iso.)

Layer 33(iso.)

fmax=0.435

Carbon fibers(iso.)

What happens upon switching from an isotropic to a transversely isotropic material model for the Carbon fibers?

For compression failure in Epoxy and Fibers

• Maximum values are reached for the same layer for isotropic material model

• Maximum values are reached for different layers for transversely isotropic material model

• Values are ~30-40% higher for the transversely isotropic material model


Isotropic Glass

fibers

Isotropic Carbon fibers

Transversely isotropic Carbon fibers

FI value Layer nr FI value Layer nr FI value Layer nr

Max Epoxy tensile FI 0.408 31 0.148 31 0.129 31

Max Epoxy compression FI 0.182 31 0.057 31 0.075 3

Max fibers tensile FI 0.438 33 0.368 33 0.394 33

Max fibers compression FI 0.835 33 0.435 33 0.593 1

Application Example


Result: Maximum Principle Stress failure (compression)

In the Carbon Fiber phase

Application Example

Layer 33 (iso.)

fmax=0.435

Layer 1(trans.)

fmax=0.593

Layer 33(trans.)

fmax=0.442

Summary

DIGIMAT enables the coupling between processing and finite element simulation based on one unique approach to material modeling

• All major FEA codes accessible

• All major injection molding codes accessible

• Drapage added with version 4.2.1/4.3.1

The concept of multiscale modeling was successfully applied to design of a wind turbine blade

• ANSYS Composite Pre/Post was coupled with ANSYS implicit solver using DIGIMAT material description

• Failure was investigated on the phase level of the material

• It was shown that it is important to take into account transversely isotropic material models when describing carbon fibers


DIGIMAT FOR CONTINUOUS FIBER

REINFORCED COMPOSITES


T h a n k y o u f o r y o u r a t t e n t i o n !

w w w . e - X s t r e a m . c o m

Documents

DIGIMAT FOR CONTINUOUS FIBER REINFORCED COMPOSITES · DIGIMAT FOR CONTINUOUS FIBER REINFORCED COMPOSITES The Challenge Continuous fiber reinforced composites in automotive industry