Outline Introduction Experimental Results Conclusion

3D Characterisation of Pore Distribution inResin Film Infused Composites

Fabien Leonard1, Jasmin Stein2, Arthur Wilkinson2,and Philip J. Withers1

1 Henry Moseley X-ray Imaging Facility, The University of Manchester2 Northwest Composites Centre, The University of Manchester

Industrial Computed TomographySeptember 20 th 2012 Wels, Austria

Outline Introduction Experimental Results Conclusion

Outline

1 IntroductionOverview

2 ExperimentalMaterialsX-ray Computed Tomography

3 ResultsVoid overviewSample L (low viscosity resin)Sample H (high viscosity resin)Sample comparison

4 Conclusion

Outline Introduction Experimental Results Conclusion

Overview

Void assessment in composites

The properties of a composite are detrimentally affected by voidsintroduced during the manufacturing process.

The common method of determining the void volume fraction is aciddigestion for carbon fibre reinforced composites and matrix burn off forglass fibre reinforced composites.

Outline Introduction Experimental Results Conclusion

Materials

Specimen Manufacturing

Epoxy resins:

triglycidylaminophenol TGAP (Araldite MY0510, Huntsman) andtetraglycidyl-4,4’-diaminodiphenylmethane

TGDDM (Araldite® MY721, Huntsman)

Hardener:

4,4’-diaminophenyl sulfone, DDS (Aradur 976-1, Huntsman)

Reinforcement:

unidirectional carbon fibre fabric supplied by Sigmatex

12 k carbon tows were bound with a fine glass fibre yarn (spacing ofapproximately 6 mm to give a fabric of 445 g.m−2)

Outline Introduction Experimental Results Conclusion

Materials

Specimens

Two composite panels were investigated in this study:

Panel L was made from unmodified resin (low viscosity resin)

Panel H was made from the same resin modified withpolyethersulfone, PES (Virantage VW-10300 FP, Solvay) to improvefracture toughness (which results in a higher viscosity resin).

Each panel (approximately 5 mm thick) was cut into five 25 mm widestrips, along the 0◦ direction.

Outline Introduction Experimental Results Conclusion

Materials

Resin film infusion

Composite laminates were manufactured by resin film infusion (RFI)which is suitable for high viscosity resins.

Resin films were degassed at 130 ◦C for 1 hour and then wereimmediately frozen.

The laminates were cured for 2 hours at at 130 ◦C, 165 ◦C, and 200 ◦C

Vacuum was applied throughout the cycle for the infusion to take place.

Outline Introduction Experimental Results Conclusion

X-ray Computed Tomography

Acquisition

Scanning was performed at the Henry Moseley X-ray Imaging Facilityon the Nikon Metrology 225/320 kV Custom Bay system:

Voxel size: 17.3 µm

Target: Cu

Voltage: 75 kV

Current: 130 µA

Filter: none

Exposure time: 2000 ms

Number of projections: 3142

Acquisition time: 1h 45’

Outline Introduction Experimental Results Conclusion

X-ray Computed Tomography

Visualisation

The visualisation software employed was Visualisation Science Groupproprietary software Avizo Fire version 7.0.1.

The voids, matrix and yarns were segmented as follows:

Outline Introduction Experimental Results Conclusion

X-ray Computed Tomography

Visualisation

The visualisation software employed was Visualisation Science Groupproprietary software Avizo Fire version 7.0.1.

The voids, matrix and yarns were segmented as follows:

Pores[0;60]

voids only

Outline Introduction Experimental Results Conclusion

X-ray Computed Tomography

Visualisation

The visualisation software employed was Visualisation Science Groupproprietary software Avizo Fire version 7.0.1.

The voids, matrix and yarns were segmented as follows:

Pores[0;60]

Yarns[150;255]

binder yarn and voids

Outline Introduction Experimental Results Conclusion

X-ray Computed Tomography

Visualisation

The visualisation software employed was Visualisation Science Groupproprietary software Avizo Fire version 7.0.1.

The voids, matrix and yarns were segmented as follows:

Pores[0;60]

Composite[60;150]

Yarns[150;255]

all labels y

Outline Introduction Experimental Results Conclusion

X-ray Computed Tomography

Visualisation

The porosity distribution measurements in 3D are focussed on theposition of the voids relative to both the edges of the panel and the yarns.

The void-to-yarn distance and the void-to-edge distance can be obtainedfrom Avizo by combining the distance maps with the thresholded voids.

raw 2D slicep

Outline Introduction Experimental Results Conclusion

X-ray Computed Tomography

Visualisation

The porosity distribution measurements in 3D are focussed on theposition of the voids relative to both the edges of the panel and the yarns.

The void-to-yarn distance and the void-to-edge distance can be obtainedfrom Avizo by combining the distance maps with the thresholded voids.

raw 2D slicep

segmented voids

Outline Introduction Experimental Results Conclusion

X-ray Computed Tomography

Visualisation

The porosity distribution measurements in 3D are focussed on theposition of the voids relative to both the edges of the panel and the yarns.

The void-to-yarn distance and the void-to-edge distance can be obtainedfrom Avizo by combining the distance maps with the thresholded voids.

raw 2D slicep

segmented voids

yarn distance map edge distance map

Outline Introduction Experimental Results Conclusion

X-ray Computed Tomography

Visualisation

The porosity distribution measurements in 3D are focussed on theposition of the voids relative to both the edges of the panel and the yarns.

The void-to-yarn distance and the void-to-edge distance can be obtainedfrom Avizo by combining the distance maps with the thresholded voids.

raw 2D slicep

segmented voids

yarn distance map

void-to-yarn distance map

edge distance map

Outline Introduction Experimental Results Conclusion

X-ray Computed Tomography

Visualisation

The porosity distribution measurements in 3D are focussed on theposition of the voids relative to both the edges of the panel and the yarns.

The distance of every voxel segmented as void to the closest yarn and theclosest edge can be measured over the entire 3D volume.

raw 2D slicep

segmented voids

yarn distance map

void-to-yarn distance map

edge distance map

void-to-edge distance map

Outline Introduction Experimental Results Conclusion

X-ray Computed Tomography

Visualisation

raw 2D slicep

segmented voids

yarn distance map

void-to-yarn distance map

edge distance map

void-to-edge distance map

Outline Introduction Experimental Results Conclusion

Void overview

Porosity Overview

Table 1: Summary of the void equivalent diameter1.

Specimen Minimum Maximum Mean Standard deviationlabel mm mm mm mm

L-1 0.027 0.398 0.078 0.055L-2 0.027 0.404 0.075 0.050L-3 0.027 0.290 0.073 0.049H-1 0.027 0.406 0.078 0.055H-2 0.027 0.458 0.074 0.051H-3 0.027 0.419 0.083 0.059

1The equivalent diameter is the diameter the void would have if it was perfectlyspherical.

Outline Introduction Experimental Results Conclusion

Void overview

Porosity Overview

Table 1: Summary of the void equivalent diameter1.

Specimen Minimum Maximum Mean Standard deviationlabel mm mm mm mm

L-1 0.027 0.398 0.078 0.055L-2 0.027 0.404 0.075 0.050L-3 0.027 0.290 0.073 0.049H-1 0.027 0.406 0.078 0.055H-2 0.027 0.458 0.074 0.051H-3 0.027 0.419 0.083 0.059

Minimum just below 0.03 mm and limited by resolution of XCT.

1The equivalent diameter is the diameter the void would have if it was perfectlyspherical.

Outline Introduction Experimental Results Conclusion

Void overview

Porosity Overview

Table 1: Summary of the void equivalent diameter1.

Specimen Minimum Maximum Mean Standard deviationlabel mm mm mm mm

L-1 0.027 0.398 0.078 0.055L-2 0.027 0.404 0.075 0.050L-3 0.027 0.290 0.073 0.049H-1 0.027 0.406 0.078 0.055H-2 0.027 0.458 0.074 0.051H-3 0.027 0.419 0.083 0.059

Maximum equivalent diameter are around 0.40 mm.

1The equivalent diameter is the diameter the void would have if it was perfectlyspherical.

Outline Introduction Experimental Results Conclusion

Void overview

Porosity Overview

Table 1: Summary of the void equivalent diameter1.

Specimen Minimum Maximum Mean Standard deviationlabel mm mm mm mm

L-1 0.027 0.398 0.078 0.055L-2 0.027 0.404 0.075 0.050L-3 0.027 0.290 0.073 0.049H-1 0.027 0.406 0.078 0.055H-2 0.027 0.458 0.074 0.051H-3 0.027 0.419 0.083 0.059

Mean void diameter ranges from 0.075 mm up to 0.084 mm.

1The equivalent diameter is the diameter the void would have if it was perfectlyspherical.

Outline Introduction Experimental Results Conclusion

Sample L (low viscosity resin)

Void size distribution

KS test on the three equivalent diameter distributions reveals that thedata are from the same continuous distribution.

Outline Introduction Experimental Results Conclusion

Sample L (low viscosity resin)

Void spatial distribution

Homogeneous distribution of voids through the panel thickness, theevenly spaced maxima reflect the regular positions of the yarns.

Outline Introduction Experimental Results Conclusion

Sample L (low viscosity resin)

Void spatial distribution

Single sharp and intense peak at a distance close to 0.12 mm whichindicates that the voids are mainly located around the yarns.

Outline Introduction Experimental Results Conclusion

Sample H (high viscosity resin)

Void size distribution

KS test on the three equivalent diameter distributions reveals that thedata are from the same continuous distribution.

Outline Introduction Experimental Results Conclusion

Sample H (high viscosity resin)

Void spatial distribution

Peak intensities increase with increasing distance from the panel edge,indicating a higher distribution of voids close to the centre of the panel.

Outline Introduction Experimental Results Conclusion

Sample H (high viscosity resin)

Void spatial distribution

Single sharp and intense peak at a distance close to 0.12 mm whichindicates that the voids are mainly located around the yarns.

Outline Introduction Experimental Results Conclusion

Sample comparison

Void size distribution

K-S test rejects the hypothesis that the two void distributions are fromthe same distribution.

Outline Introduction Experimental Results Conclusion

Sample comparison

Void size distribution

K-S test rejects the hypothesis that the two void distributions are fromthe same distribution.

Outline Introduction Experimental Results Conclusion

Sample comparison

Void spatial distribution – qualitative

Homogeneous void distribution for panel L and higher void distributionclose to the centre of panel H.

Outline Introduction Experimental Results Conclusion

Sample comparison

Void spatial distribution – qualitative

Similar sharp peak around 0.12 mm which indicates that the voids aremainly located around the yarns for both specimens.

Outline Introduction Experimental Results Conclusion

Sample comparison

Void spatial distribution – quantitative

50 % of the voids lie within the middle 2.5 mm of panel L50 % of the voids lie within the middle 0.5 mm of panel H

Outline Introduction Experimental Results Conclusion

Sample comparison

Void spatial distribution – quantitative

90 % of the voids are located within 0.25 mm from the yarns in panel L90 % of the voids are located within 0.50 mm from the yarns in panel H

Outline Introduction Experimental Results Conclusion

Summary

Summary

Summary:

Composite panels have been manufactured by resin film infusion

The pore distribution in the panels has been fully characterised

Highlights:

No major difference between specimens with standard pore analysis

The void-to-yarn and void-to-edge distance maps showed majordifferences between the panels:

Homogeneous void distribution for panel L and higher voiddistribution close to the centre of panel H.In both panels, the pores are mainly located around the yarns.

Both qualitative and quantitative analyses can be performed

Outline Introduction Experimental Results Conclusion

Discussion

Discussion

Questions ?

Fabien Leonardfabien.leonard@manchester.ac.uk