Simulation of the Damage and Failure Behaviour of Flow Drill … · © VIRTUAL VEHICLE Flow Drill...

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COMET K2 Competence Center - Initiated by the Federal Ministry of Transport, Innovation & Technology (BMVIT) and the

Federal Ministry of Science, Research & Economics (BMWFW). Funded by FFG, Land Steiermark and Steirische Wirtschaftsförderung (SFG)

Simulation of the Damage and Failure Behaviour of Flow Drill Screw

Joints between Fibre-Reinforced Plastics and Aluminium by using User-

Materials Szlosarek, R.a, Karall, T.a, Hahne, C.b, Berger, A.c, Meyer, N.d, Enzinger, Ne

aVirtual Vehicle Research Center

bAUDI AG cEngineering System International GmbH

dTU Darmstadt, Fachgebiet Konstruktiver Leichtbau und Bauweisen eTU Graz, Institut für Werkstoffkunde und Schweißtechnik

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Motivation

22.05.2014 Numerical Modelling of the Damage and Failure Behaviour of Flow Drill Screw Joints

between Fibre-Reinforced Plastics and Aluminium 2

oUS-NCAP

o 56 km/h

o rigid wall

oChrysler Neon

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Flow Drill Screw Joints between CFRP-Aluminium

09.10.2014 Simulation of the Damage and Failure Behaviour of Flow Drill Screw Joints between

Fibre-Reinforced Plastics and Aluminium by using User-Materials 3

micrograph test specimen

flow drill screw

CFRP

aluminium

only a one-sided accessibility is necessary

low thermal impact

minor requirements for part preparation

chipless process the thread in the aluminium part is perfectly connected to the screw with no clearances

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Joining Process



(1) Placement of the screw in the pre-hole

(2) Forming of the through draught

(3) Yielding of the aluminium starts



(6) Pre-stressing of the screw by a defined torque

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Roadmap




experiment detailed simulation

Flow drill screw joint between CFRP - aluminium

ViF K2 Projekt: Audi, ESI, KLuB, IWS

analogous model

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Roadmap




experiment



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Modified KSII-Test Facility



test specimen

0°

aluminium: EN-AW6060-T6; thickness 2,5 mm

CFRP: laminate with 8 layers (0/90/45/-45)s;

thickness 1,2 mm

modified LWF KS2 test facility of the Laboratory for Materials and

Joining Technology of the University of Paderborn

Experiment

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Damage and Failure under Cross Tension



Video recording of the damage and failure behaviour under cross tension

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Damage and Failure under shearing Load



• good reproducibility of the tests

• bearing as dominant failure mode

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Force-Displacement-Curves



100 %

50 %

25 %

75 %

• nearly the same maximum force under all tested loading angles for the tested

combination of CFRP and aluminium

Test results under various loading angles

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Roadmap







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Why a Detail Simulation?



Modelling of the elastic behaviour

Simulation of the damage and failure behaviour

Study of additional loading situations

Analysis of other material combinations

virtual design

real experiments numerical experiments

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Finite Element Model



Finite element model Real test facility

• Using symmetries and the results of the optical displacement measurement

reduction of the model

reduction of computation time within the same result quality

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Pre-load of the Joint



1. Stage: pre-load of the screw

to take the joining process into account

2. Stage: loading of the screw

strength analysis

F

u u u

Multi-stage analysis to regard the pre-stressing

stress transfer

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Pre-load of the Joint



stress σ3

Pre-stress of the laminat

1

3

2

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Material Modelling



Screw, aluminium, clamp

rigid body

Test facility (steel S370 and aluminium)

material models are available

CFRP, 8 layers (0/90/45/-45)s

user-material by using the inter-fibre

failure criteria of Puck

Material Models

0°

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User-material model



transformation of the stresses into an action plane

determination of the fracture angle is mandatory

- inter-fibre fracture criteria of Puck is based on the fracture hypothesis of Mohr

Modelling of inter-fibre fracture

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Modelling of the Degradation



Modelling of an increasing crack density (smeared crack modelling)

stress-strain extrapolation method after Schürmann

the stress is kept constant with an increasing crack density

no additional stress could be transferred after inter-fibre fracture occurs

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Degradation model

• Stresses on the action plane are kept constant



degradation model depends

on the fracture angle!

constant:

constant:

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Analogous Model



Using shell and beam elements for large structures

- non-linear force-displacement-curves

- user-defined rupture model

- usage of MPC-Links

forc

e

(0/90/45/-45)s shearing load (0/90/45/-45)s cross tension test

displacement

forc

e

N1

N2

Link-Element

simulation

average tests

test 1

test 2

test 3

simulation

average tests

test 1

test 2

test 3

displacement

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Visualization of the LINK Elements

Example: multi material profile



- length for the normal force

- diameter for the shearing force

- colours for the damage

CFRP

Aluminium

FDS

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Conclusion



Modified test facility and data analysis due to test specimens

made of CFRP

User-defined material model which enables a detailed

simulation of the damage and failure behaviour of FRP

Analogous model for the use joint modelling in large

structures

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The authors would like to acknowledge the financial support of the "COMET K2 - Competence Centres for Excellent Technologies Programme" of the Austrian

Federal Ministry for Transport, Innovation and Technology (bmvit), the Austrian Federal Ministry of Science, Research and Economy (bmwfw), the Austrian

Research Promotion Agency (FFG), the Province of Styria and the Styrian Business Promotion Agency (SFG).

The authors would, furthermore, like to express their gratitude to their supporting industrial and scientific project partners, namely Audi AG, ESI GmbH, Institut

für Werkstoffkunde und Schweißtechnik at Technical University of Graz, Fachgebiet Konstruktiver Leichtbau und Bauweisen at Technical University of

Darmstadt.

Robert Szlosarek [email protected] www.v2c2.at

Thomas Karall [email protected] www.v2c2.at

Clemens Hahne [email protected] www.audi.de

André Berger [email protected] www.esigmbh.de

Nils Meyer [email protected] www.klub.tu-darmstadt.de

Norbert Enzinger [email protected] iws.tugraz.at

http://www.v2c2.at/

Simulation of the Damage and Failure Behaviour of Flow Drill … · © VIRTUAL VEHICLE Flow Drill...

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