Uk Rum 13 BingZhang

8/9/2019 Uk Rum 13 BingZhang

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Micro-Mechanical Finite Element Analysis

of Single Z-pin Pull-out

Bing Zhang, Giuliano Allegri

www.bris.ac.uk/composites

Advanced Composites Centre for Innovation and Science (ACCIS), University of Bristol


2/21

2/XXIntroduction

Z-pinning is an effective through-thickness reinforcement techniquewhereby small diameter rods (Z-pin) are inserted perpendicularly

into laminate composites to improve delamination resistance andother through-thickness properties.

Characteristic features of Z-pinned composite laminates

In-plane features (Mouritz, 2007) Out-plane features(Chang, 2006)


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3/XXIntroduction

A three-dimensional FE strategy for single Z-pinned laminates

undergoing Mode I dominated pullout is presented

Single Z-pin analysis provides fundamental understanding ofreinforcement mechanism.

Diagram of single Z-pin test Mode I test


4/21

4/XXFE modelling and results

! Mesh generation

! Materials definition

! Interface between Z-pin and laminates/resin

! Definition of boundary conditions and Mode I simplification

! Results and discussions

! Conclusions


5/21

5/XXMesh Generation

1. Ply level mesh

Ply-level mesh

Stacking

Z-pin misalignment meshing

2. Stacking

Fibre direction definition


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6/XXMesh Generation

3. Full mesh

Full model

Top block

Bottom block

Z-pin

Experimental sample

Z-pin misalignment in full model

7/XX


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7/XXMaterials definition

Laminate(IM7/8552) Z-pin (T300/9310)

Young modulus, El(Gpa) 161 144

Young modulus, Et(Gpa) 11.38 7.31Shear modulus, Glt(Gpa) 5.17 4.45

Shear modulus, Gtt(Gpa) 3.98 2.63Poissons ratio, vlt 0.32 0.25

Poissons ratio, vtt 0.436 0.39

Thermal coefficient, !tt(C-

) 3.0e-5 3.0e-5Thermal coefficient, !ll(C

-) 0 0

8552 neat resin

Young modulus, E (Gpa) 4.67Shear modulus, G (Gpa) 1.73

Poissons ratio, v 0.35

Thermal coefficient, !(C- ) 7.5e-5

8/XX


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8/XX

t!

n!

1)0,max(

2

max,

2

max,

=!!"#$$

%&+!!

"#$$

%&

t

t

n

n

'

'

'

'

1=!!"

#$$%

&+!!

"

#$$%

& ''

IIC

II

IC

I

G

G

G

G

!

max,n!

max,t!

max,m!

)0,max(dkn

!="

d0 0 d0 d

Modified Coulomb Friction after debonding

n! t

!

),)1),0,min(max(max( max,0

00 tnt

d

dd!!!! "+

#

"=

max,t!

Bonding between Z-pin and laminates/resin

Interface between Z-pin and laminates/resin

Interface modelled by Vuinter of Abaqus/Explicit

9/XX


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9/XXInterface between Z-pin and laminates/resin

*SURFACE INTERACTION, PADTHICKNESS=0, NAME=USERINTER, USER,DEPVAR=33, PROPERTIES=11

**!Imax, !IImax, KI, KII, GI, GII, ", c30., 60., 1.e+5., 1.e+5, 1.e+5, 1.e+5, 1, 0.03,

** #, s0, smax

0.8, 25, 40

Input script of VUINTER

blank line

cohesive law properties

friction law properties

10/XX


10/21

10/XXDefinition of boundary conditions & Mode I simplification

Boundary condition definition in cure step

Temperature Field:-160C w.r.t. cure

Whole analysis consists of cure step and pull-out step


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12/XX


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12/XX

Simplification for Mode I dominated pull-out

!

!

Simplification of Mode I Pull-out angle definition

Definition of boundary conditions & Mode I simplification

13/XX


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13/XXResults and Discussions

0.3s 0.6s 1.0s

Uni-directional (UD)- cure results

debonding initiation debonding

bonding

interface tension

interface compression

14/XX


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Uni-directional (UD)- pullout results

Pull-out of Z-pin from UD laminates Enhanced friction zone

15/XX


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Uni-directional (UD)- pullout results

Reaction force vs. displacement curves of Z-pin pull-out from UD

complete debonding

frictional pull-out

16/XXl d


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Quasi-isotropic (QI)- cure results

0.3s 0.6s 1.0s

almost complete debondingdebonding initiation location

17/XXR lt d Di i


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Quasi-isotropic (QI)- pullout results

Reaction force vs. displacement curves of Z-pin pull-out from QI

negligible influence ofinterface debonding

18/XXR lt d Di i


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0.3s 0.6s 1.0s

Zero-dominated (ZD)- cure results

debonding initiation

almost complete debonding


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21/XXAcknowledgements


21/21

/Acknowledgements

Thanks for your attention

!

The authors would like to acknowledge Rolls-Royce plc for havingsupported this research via the Composites University Technology

Centre (UTC) at the University of Bristol.

!

The authors are also grateful to Dr Mehdi Yasaee, Dr JamesLander and Dr Fabrice Helenon for the discussion of theexperimental results and the modelling strategy.

Uk Rum 13 BingZhang

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