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Application of 3D Woven Compositesfor Energy Absorption

September 9-11, 20152015 SPE Automotive Composites Conference & Exhibition

Novi, MI USA

J. Goering, H. Bayraktar, B. Stevenson, M. McClain & D. EhrlichAlbany Engineered Composites, Inc.

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Presentation Outline

• Introduction to 3D woven composites

• Benefits of 3D reinforcement

• Specific energy absorption testing

• Results and conclusion

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Factors Motivating The Development Of 3D Composite Technology

Reduce cost

Reduce touch labor whenever possible• Near net shape preforming• Highly automated manufacturing

Eliminate process waste wherever possible• Near net shape preforming

Near net shape preformingcombined with liquid molding

techniques address both factors simultaneously

Improve performance

Eliminate joints, bondlines, and delaminations• Multilayer interlocking textile preforms• Integrated/multifunctional structures• Through-thickness reinforcement

Place fiber where it is does the most good• Follow natural contours• Through-thickness reinforcement

3D woven fanblade preform loaded into RTM tool

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3D Woven Preforms Consist OfMultiple Interlocking Layers Of Fiber

Warp Columns

Weft Columns

1

2

3

4

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Jacquard Weaving Is At The Heart Of 3D Preforming Technology

Warp stuffers

Warp weaverWeft

X (Warp)

Z

Jacquard weaving allows each fiber to follow an

independent path

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Typical Cross Sectional Shapes Made Possible Through 3D Weaving

Continuous fiber across intersecting elements is a common characteristic of

3D woven preforms

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3D Preforming Enables Highly EngineeredComposite Material/Structural Systems

Integratedfeatures Variable

geometry

Variableproperties

Tailoredreinforcement

Common benefits include:• Improved damage tolerance• Eliminate delaminations• Optimized load paths• Minimized touch labor• Minimized process waste

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Improved Through-Thickness StrengthOf 3D Composites Relative To Laminates

Inter-laminarfailure

ASTM D6415 curved beam test

Through thickness

cracks

3D composites eliminate delamination

as a mode of failure

Fiberfailure

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3D Composites Display More Benign Failure (Progressive Damage)

3D Composite

Laminate0

100

200

300

400

500

600

700

800

0 0.005 0.01 0.015 0.02 0.025

Fle

xura

l Str

ess

(MP

a)

Strain (mm/mm)

3D orthogonal

3D ply-to-ply

2D fabric

Fiber architecture controls the trade

between stiffness and damage tolerance

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3D Composites Display Good Off-Axis Bearing Properties Without Off-Axis Fiber

Loading Direction (degrees)

Bea

ring

stre

ngth

(MP

a)

IM7/ST-1550/50 Ply-to-ply

2% offset strength

Bea

ring

Str

ess

(MP

a)

Strain (%)

ASTM D5961BSingle Shear

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SEA Testing With Sinusoidal Specimens

• Test configuration developed by P. Feraboli• 75mm x 50 mm x ≈4mm thick• 45° chamfer on top edge

• Crush tests at several rates• All configurations in quasi-static crush• Best QS configurations dynamically

• 2D & 3D composites

• 3D orthogonal and ply-to-ply architectures

• Structural /material property used for relative comparison purposes only

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Quasi-Static & Dynamic Tests Were Performed

Quasi-static crushInstron universal test machine

0.05m/min crush rate

Dynamic crush14’ drop tower

1.7m/s & 6.4m/s impactWeight adjust to crush ≈½ specimen

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2D & 3D Specimens Were Tested

• [(902/±60)2]s 2D-F (Fragmentation failure)• [902/±452/02]s 2D-B (Brittle fracture failure)• [90/(±30/0)2/0]s 2D-S (Fiber Splaying failure)

• Orthogonal architecture• 50/50 warp/weft ratio O-50 & O50T• 70/30 warp/weft ratio O-70

• Ply-to-ply architecture 1• 50/50 warp/weft ratio P50-1• 70/30 warp/weft ratio P70-1

• Ply-to-ply architecture 2• 50/50 warp/weft ratio P50-3 & P50-3T

Carbon/epoxy composites• AS4C standard modulus carbon fiber• Epon 862 with curing agent W epoxy (except where noted)• “T” postscript denotes PR520 toughened epoxy

2Dconfigurations

3Dconfigurations

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High-Speed Videos Of SEA TestTypical Result For 3D Ply-to-ply Architecture

Front Side

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3D Orthogonal Architectures Performed Best In Quasi-Static Crush Tests

50% improvement

3D Woven Composites 2D Laminates

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Toughened Epoxy May Provide MoreBenefit For Higher Velocity Events

Interaction between fiber architecture and

resin type requires further study

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Extent Of Damage in 2D Composites Is Greater Even Though SEA Is Less

3D Orthogonal architecture crushed at 6.4m/s

2D fiber splaying laminatecrushed at 6.4m/s

SEA is inversely proportional to crack length2D composites delaminate which is not a failure mechanism for

3D woven composites

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Conclusions

• 3D woven composites exhibit improved SEA relative to 2D composites in axial crash load scenarios

• Orthogonal architectures showed increase in SEA over ply-to-ply architectures

• Increase in SEA for 3D woven composites over 2D is due to lack of delamination as a failure mode leading to less crack propagation

• 3D composites dissipate energy by forming new cracks rather than driving existing cracks

• Toughened epoxy improves SEA for 3D composites, but interaction between resin type and fiber architecture in to well understood

• Good SEA can be obtained with low cost, un-toughened epoxy resins