The Use of Composite Materials in the Automotive Industry

The Use of Composite Materials in the

Automotive Industry

- Challenges in the simulation of continuous

fiber reinforced thermoplastic parts

-

Andreas Wüst – BASF SE

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AU 2013

Content

Motivation

The Lightweight challenge

Continuous fiber reinforced thermoplastic parts

Ultracom™ Demonstrator Part

Part development with Ultrasim®

Material modelling

New Optimization Technologies

Draping Simulation

Overmolding simulation

Warpage / Reheating

Interface Modelling (Short/Continuous Fiber areas)

Summary and Outlook

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OEM

Tier 1

Tier 2

BASF as raw material supplier

3

Raw Material

Service

CAE Service

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3 former BASF

Business Units

Now: 1 Business Unit Performance Materials

BASF Lightweight Team

Combination of Composite Competences

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+ Matrix

PU EP PA

Fibers

Part =

The Lightweight Challenge

Better vehicles reduce the carbon footprint!

Better engines

Aerodynamics

Lightweight structures

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Lightweight Design

Better parts by combination of

different fiber lengths

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Injection

molding

Geometrical

complexity

Thermo-

forming

unreinforced

Ultramid®

(short fiber)

Ultramid®

Structure

(long fiber)

Ultralaminate™

(orthotropic)

Ultratape™

(unidirectional)

Combination of

thermoforming

and injection molding

complex parts with

high stiffness and

strength

Stiffness / Fiber Length

Ultracom™ – for continuous-fiber reinforced

composite parts

7

Ultracom™

Semi-finished product

(Composites)

Overmolding material:

Compounds Service package

Tapes / Laminates

Ultramid® COM

Ultradur® COM

Ultralaminate™

Ultratape™

Simulation

+

Processing

+

Part testing

Processing steps

Heating of Preforms

above 220°C

Positioning of the

heated preform

Forming

+ Overmoulding

Cooling and

Demoulding

Preforms = Laminate and/or stacked tape layup

Ultracom™

Manufacturing cell and demonstration part for in-mold forming and overmolding

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9

Variety of different

ribs / wall thickness

transitions between the

laminate and

overmolded material

Overmolded edges

Stitch elements,

i.e. locations in the

laminate through which

material is injected

Rib array for special

crash investigations

Punched or formed

holes for use as

mounting elements

Beam with ribbed U-profile

Size: 40 cm x 40 cm

Height: 4.5 cm

Thickness of laminate: 1.5 mm

Ultracom™

Manufacturing cell and demonstration part for in-mold forming and overmolding

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Injection

molding

machine

Storage

for

laminates

Heating

station

Clamping

frame with

inserted

laminate

Six-axis robot

Automatic

insertion of

laminate into

the clamping

frame

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• Anisotropic

• Nonlinear

• Strain-rate sensitive

• Tension-compression asymmetric

• Failure modeling

The two pillars of ULTRASIM® Do the right things right!

Process simulation

Mechanical Simulation

Mathematical Optimization Parameter

Shape

Topology

Material modelling -

Integrative Simulation

CAE Methods +

Mathematical Optimization

ULTRASIM®

Calculate the

part

right

Calculate the

right

part

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• Anisotropic

• Nonlinear

• Strain-rate sensitive

• Tension-compression asymmetric

• Failure modeling

Local reinforcements and ULTRASIM

Process simulation

Mechanical Simulation

Mathematical Optimization Parameter

Shape

Topology

Composite

Material modelling -

Integrative Simulation

CAE Methods +

Mathematical Optimization

ULTRASIM®

Measurement Process

Material

Part

• Anisotropic

• Nonlinear

• Strain-rate sensitive

• Tensile-compression

asymmetric

• Failure modelling

• Temperature dependent

Integrative Simulation ULTRASIM™ for short fiber reinforced thermoplastics

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Measurement Process

Draping / Overmolding

Material

Part

Integrative Simulation ULTRASIM®

for Continous Fiber Reinforced Plastics

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• Anisotropic

• Nonlinear

• Strain-rate sensitive

• Tensile-compression

asymmetric

• Failure modelling

• Temperature dependent

Material Characterization

Tensile Test

Angular Variations

3 Point Bending

Puncture Test

Compression Test

Sheartests

Tensile 45°

Shear Frame

Molding Trials

Overmolding

Draping

Picture frame

Part tests

• Orientation • Strainrate • Wallthickness • Humidity • Temperature

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Optimization – General Intro Topology – Shape – Parameter – Topography - Composite

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• Topology Optimization

Where are the main loadpaths in the design space?

• Composite Optimization

Challenges in Composite Optimization

Fiber placement in composite parts

Which fiber type? - CF/GF?

Where?

Direction?

Thickness?

No. of Layers?

Stacking sequence?

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Optimisation Basis

Standard FE simulation

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Geometry model – FE meshing

Definition of load cases

Boundary & Fixation conditions

Simplified material model: orthotropic, layered material (E1, E2, n12)

Assumption: e.g. 4 ply orientations 0° / 90° / +45° / -45°

Thickness of individual ply e.g. 1 mm

Optimisation in three phases – phase 1

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Phase 1: Concept

Which fiber orientation is required -

where? – with which thickness?

A Free-Size-Optimisation delivers a

distribution of thicknesses for each

defined fiber orientation. This allows

the definition of ply shapes.

Concept

Phase 1 – Setup

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Design variables: Thickness of single plies per element

Boundary constraint: Maximum displacement at tip u ≤ 0.6

Manufacturing Constraint.: Coupling of ±45° plies

Objective: Minimize mass

Concept

Optimisation in three phases

Phase 1 – convergence and results

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Mass declines and

approaches limit

Boundary

condition met

3.2 mm

0 mm

Wall thickness

Total wall thickness

Concept

Optimisation in three phases Phase 1 – Result of individual plies Ply Shapes!

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1.0 mm

0 mm

Thickness

of single ply

Fabric ply 1 – 0°

Fabric ply 1 – 0°

Concept

Optimisation in three phases – phase 2

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Phase 2: Dimensioning

How many individual plies are

required?

A Discrete Size-Optimisation

delivers the optimum number of plies

for each defined fiber direction.

• Optimum thickness of a ply: e.g. 0.53 mm

• Individual thickness of (real) ply 0.2 mm

• Use 3 plies of 0.2 mm

Optimisation in three phases

Phase 2 – Setup

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Mass declines and

approaches limit

Design variables: Discrete number of single

plies per fiber direction

Constraints:

• Maximum displacement at tip < 0,6

• Stresses lower than defined level

Process constraints:

Coupling of +45° plies

Objective:

Minimize volume (mass)

Initial ply shape

definitions

Optimisation in three phases

Phase 2 - Result

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Number:

Stacking order:

Result of phase 2:

Number of plies per direction

4

4

4

2

Optimisation in three phases

Phase 3

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Stacking order Phase 3: Stacking order

In which order should the plies be

stacked?

A Shuffle-Optimisation determines the

optimum ply order by following pre-

determined (or established) ply-book rules.

Optimisation in three phases –

Phase 3 – Shuffling Result

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Phase 2:

Number

Number:

Sequence:

Phase 3:

Number + Sequence

Plybook rules

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Examples for established rules:

The maximum number of successive plies with identical

orientation is N!

The orientation of the outer plies is pre-defined!

Balance / Pair constraints:

Coupling of thickness of shear plies (e.g. +45° / -45°)

Draping-Simulation

Material data for draping simulation

Picture Frame Test

FE Modelling details

Examples

OPC Seat

CIFO Part

– I-Shape

– J-Shape

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Material data for draping simulation

Tests done at IVW Kaiserslautern

Picture Frame Test at elevated temperatures

Tensile Test

Dry and consolidated fabric

Simulation issues

1. Evaluate material models and modelling method

for simulation

2. Simulate Picture Frame Test

3. Simulate BASF Test-Tool geometry

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Simulation of Picture Frame Test

31

Animation of simulation

Simulated and measured curves

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Simulation of Test-Tool geometry

32

Animation of simulation Real Draping Test

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Draping Simulation Studies

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with blankholders without blankholders

Draping Simulation Comparison: Reality (CT) and Simulation

Detail: Local Indentation

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Real Part shows no

visual defects

CT shows fiber

relocations

Simulation shows

slight wrinkling

Astra OPC Seat

General Intro

Draping Simulation

Overmolding simulation

Filmclip Simulation

Interface Laminate / Ribs

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Serial Front Seat Pan Opel Astra OPC

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Overmolding material Ultramid®

PA6 short glass fiber material

Thermoplastic laminate based on

Ultramid® PA6 and glass fibers

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Draping and Overmolding Simulation

Ultracom Demonstrator Part

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Process Simulation

Warpage

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Insert made of

Thermoplastic

Laminate

Overmolded zones

made of short glass

fiber material

Combined FE-Model for

Warpage

S • anisotropic mechanical properties

• anisotropic thermal properties

• temperature gradients throughout

laminate due to heating and

overmolding

• anisotropic fiber orientation leads

to anisotropic mechanical and

thermal properties

• shrinkage gradient throughout

part due to injection molding process

• temperature gradients throughout

overmold due to contact with

laminate and mold

Warpage Shrinkage contribution: Short fiber plus endless fiber

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New Development:

MOLDFLOW 2015 Beta Version:

Anisotropic Inserts!

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Process Simulation

Warpage

First tests:

• Ultracom Demonstrator with Moldflow (anistropic inserts in new beta version for BASF)

• Opel OPC seat with ULTRASIM (non-linear, anisotropic CFRP model)

Pictures from MOLDFLOW 2015 Beta-Version

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Challenge: Reheating, melting and filling

of laminate „inserts“

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Laminate

Overmolding

material

Crossover

through

laminate

Cross section

Fluid flow

Interface Modelling

43

ULTRACOM®

Overmolding material

Thermoplastic

Laminate

Tensile-Shear Test

Tensile Test

CT-Foto

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Rheological Investigation

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Filling

Overmolding

Simulation

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Modelling with Contact (only 3D) ULTRASIM® Modelling (2D+3D)

Simulation

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Tensile Test symmetric

Tensile Test asymmetric

Summary and Vision

New class of continuous fiber reinforced thermoplastic materials

add value to thermoplastic parts

can contribute to lightweight design

Needs new simulation tools

Material modelling

Optimization

Draping

Overmolding

Shrinkage and Warpage

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