Understanding the High Temperature & Fire Performance of Composites

AP MouritzRoyal Melbourne Institute of Technology (RMIT University)

e-mail: adrian.mouritz@rmit.edu.au

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Research overview

• Understand high temperature & fire response of composites for diverse structural applications

• Understand following about composites in fire:

• thermal response

• damage & decomposition

• softening & failure

• residual mechanical properties

• Fire modelling & testing:

• Material level (fibre/ply/laminate)

• Structural level (component)

• Material systems:

• fibre-polymer laminates

• sandwich composites

• fibre metal laminates

Research vision

Towards a user-friendly generic modelling “toolbox” to predict thermal response, damage, burn-through & structural

integrity of composites during & following fire exposure.

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Research progress

• Models to predict temperature rise in laminates & sandwich composites exposed to fire.

• Models to predict decomposition & burn-through in laminates & sandwich composites exposed to fire.

• Models to predict softening & failure of laminates & sandwich composites exposed to fire.

• Models to predict post-fire mechanical properties of laminates & sandwich composites exposed to fire.

• Models to predict fire protection provided by passive and reaction coatings on laminates & sandwich composites exposed to fire.

Experimental validation

Experimental validation at different length scales has been central to our models

Fibre damage (<10 microns)

Microstructural damage (<1 mm)

Coupon testing (<0.5 mm)

Intermediate-scale testing (1 m)

Large-scale testing (3 m)

incre

asin

g e

xp

erim

en

tal s

cale

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Thermal Analysis ofHot, Decomposing Composites

Thermal model

Fire reaction of polymer laminates & sandwich composites is a complex interactive problem

Hea

t F

lux

Fire-damaged

carbon/epoxy laminate

• Model developed to calculate temperature for any thermal flux condition of the fire.

• Model validated for composites tested at heat flux conditions from 10 kW/m2 (~250oC) to 100 kW/m2 (~800oC).

solid lines represent predictions

Thermal model

Hea

t F

lux

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Decomposition Analysis of Composites

Decomposition model

Decomposition of laminates & sandwich composites to char is calculated using Arrhenius rate model.

0 2 4 6 8 10 120

20

40

60

80

100

Glass/polyester fabric

charmodel25.opj

Measured Char Thickness = 5.78 ± 1.23 mm

Rem

ain

ing R

esin

Conte

nt (%

)

Depth Beneath Hot Face (mm)

char virgin laminate

solid line represents predictions

He

at

Flu

x

0 2 4 6 8 10 120

2

4

6

8

10

12

charmodel27.opj

carbon/epoxy tape (50 kW/m2)

carbon/epoxy tape (75 kW/m2)

carbon/epoxy tape (100 kW/m2)

carbon/epoxy fabric (50 kW/m2)

glass/polyester fabric (25 kW/m2)

glass/polyester fabric (50 kW/m2)

glass/polyester fabric (75 kW/m2)

glass/polyester fabric (100 kW/m2)

glass/epoxy fabric (50 kW/m2)

glass/vinyl ester fabric (25 kW/m2)

glass/vinyl ester fabric (50 kW/m2)

glass/vinyl ester fabric (75 kW/m2)

glass/vinyl ester fabric (100 kW/m2)

glass/phenolic fabric (25 kW/m2)

glass/phenolic fabric (50 kW/m2)

glass/phenolic fabric (75 kW/m2)

glass/polyester mat (50 kW/m2)

glass/epoxy mat (50 kW/m2)

Measure

d C

har

Thic

kness (

mm

)

Theoretical Char Thickness (mm)

Accurate prediction of decomposition (char) for many composites under range of heat flux conditions.

Decomposition model

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Softening & Failure of Composites

Compression model

Compressive

Load

Compressive

Load

Modelling based on the four step analysis:

1. Calculation of through-thickness temperature profile in composite

2. Calculation of temperature-dependent compression strength (matrix softening) at many points through the composite

3. Calculation of bulk strength of the composite

4. Prediction of compression failure.

Compression properties of polymer laminates & sandwich composites exposed to fire

He

at

Flu

x

Experimental validation of compression model using laminates & sandwich composites.

Compression model

0 300 600 900 1200 15000.0

0.2

0.4

0.6

0.8

1.0

75 kW/m2 (800

oC)

50 kW/m2 (600

oC)

25 kW/m2 (440

oC)

No

rma

lise

d C

om

pre

ssiv

e S

tre

ss

Time-to-failure (s)

glass/vinyl ester laminate

Model validation for polymer laminates & sandwich composites

failure time decreases with increasing applied stress & heat flux

plastic kinking failure

Compression model

Tension

Load

Tension

Load

Modelling based on the five step analysis:

1. Calculation of through-thickness temperature profile in composite

2. Calculation of temperature-dependent tension strength of polymer matrix at many points through the composite

3. Calculation of temperature-time dependent strength of fibres at many points through the composite

4. Calculation of bulk tensile strength of the composite

5. Prediction of tensile failure.

Tension properties of polymer laminates & sandwich composites exposed to fire

Tension model

Experimental validation of tension model using laminates & sandwich composites

Tension model

Experimental validation of tension model.

Failure can occur after complete matrix decomposition.

solid lines represent predictions

Tension model

1 10 100 10000

50

100

150

200

250

Time (s)

Applie

d tensile

str

ess (

MP

a)

Tension

Load

Tension

Load

Outstanding research problems

• Past ten years characterised by major progress in fire modelling of composites.

• However, challenges remain.

– Mechanistic-based models for softening & oxidation of fibres at high temperatures.

– Model for predicting delamination cracking in hot, decomposing composites

– Model for various damage & failure modes of sandwich composites in fire

– Scaling laws

– Comparative studies with structural metals

– User-friendly modelling toolbox for composites in fire.

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• A.P. Mouritz, S. Feih, A. Afaghi Khatibi, B.Y. Lattimer and S.W. Case, United States Office of Naval Research Grant, ‘Fire

Modeling and Testing of Aluminum Alloys and Structures’, 2013-2016, N000141310590.

• A.P.Mouritz United States Office of Naval Research, International Workshop on Naval Structural Life Assessment Methodologies,

2011, N62909-11-1-7031.

• S. Feih, A.P. Mouritz, S.W. Case and A.P. Mouritz, United States Office of Naval Research, ‘Deformation modelling of naval

composite structures in Fire: Sensitivity Analysis and Optimization’, 2010, N00014-11-1-0223.

• S. Feih, A.P. Mouritz, S.W. Case and A.P. Mouritz, United States Office of Naval Research, ‘Fire Structural Properties of

Sandwich Composites’, 2010, N00014-12-1-0248.

• A.P. Mouritz, S. Feih, B.Y. Lattimer and S.W. Case, United States Office of Naval Research Grant, ‘Modeling of Aluminum Naval

Structures During and Following Fire’, 2010-2012, N00014-10-1-0690.

• A.P. Mouritz, United States Office of Naval Research Grant, ‘Development and Application of Fire Resistive Models for Naval

Composite Structures’, 2007-2009, N00014-07-0514.

• B. Lattimer and A.P. Mouritz, United States Office of Naval Research Grant, ‘Structural Integrity of Aluminum during Fires’, 2007-

2009, N00014-08-1-0300.

• A.P. Mouritz, United States Office of Naval Research Grant, ‘Structural properties of composites in fire’, 2003-2006.

• A.P. Mouritz, United States Office of Naval Research Grant, ‘Fire book’, 2002

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• Dr Stefanie Feih (RMIT)

• Dr Everson Kandare (RMIT)

• Ms Katherine Grigoriou (RMIT)

• Ms Zenka Mathys (DSTO)

• Prof Geoff Gibson (Uni. Newcastle)

• Prof Scott Case (Virginia Tech)

• Prof Brian Lattimer (Virginia Tech)