SIP-IMASM 2016 Development of Composite Materials … · Development of Composite Materials for...

© 2016 MITSUBISHI HEAVY INDUSTRIES, LTD. All Rights Reserved. SIP-IMASM 2016

Development of Composite Materials for Aircraft Structures

SIP-IMASM 2016

AIST Tsukuba Center, Japan 27, Sept. 2016

Kiyoka Takagi Mitsubishi Heavy Industries, Ltd.

Integrated Defense & Space Systems Koichi Hasegawa

Mitsubishi Heavy Industries, Ltd. Research & Innovation Center

© 2016 MITSUBISHI HEAVY INDUSTRIES, LTD. All Rights Reserved.

SIP – IMASM 2016

Outline

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This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “Structural Materials for Innovation” (Funding agency: JST).

Feature of Carbon Fiber Reinforced Plastic (CFRP)

CFRP Application in Aircraft

Static Strength of CFRP

Damage Tolerance of CFRP

Inter-layer Damage Growth Mechanisms

Improving Damage Growth Resistance

Introduction of SIP unit A11


SIP – IMASM 2016

Strength of Fiber Reinforced Plastic

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CFRP(HT)： Carbon Fiber Reinforced Plastic

（High Tension Strength Type）

CFRP(HM)：Carbon Fiber Reinforced Plastic

（High Modulus Type）

AFRP: Aramid Fiber Reinforced Plastic

GFRP：Glass Fiber Reinforced Plastic

BFRP：Boron Fiber Reinforced Plastic

SiC(CVD)：Silicon Carbide Fiber

（Chemical Vapor Deposition）

LAS：Lithium Alumino-Silicate Glass

(Ref. 日本複合材学会Home Page)

Specific Modulus

Spe

cific

Stre

ngth

Fiber Reinforced Plastic

Metal Fiber

Reinforced Metal

Pitch

Pitch

CFRP is high specific strength and high specific modulus

Ref: MICHAEL･C・Y・NIU 「COMPOSITE AIRFRAME STRUCTURES」

FIBER RESIN


SIP – IMASM 2016

Special Feature of CFRP

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High Fatigue Resistance!

(Ref: Japan Chemical Fibers Association HP)

Cycle Number

(Ref: Aviation Safety Bureau HP)

Metal Structure ⇒ Corrosion CFRP ⇒ No CORROSION!


SIP – IMASM 2016

Out-of-Plane Strength of CFRP

4

Out-of-Plane strength is 1/10 of in-Plane

EXTREMELY WEAK

Ftu

Ftu

1/10×Ftu

The Cause of Problem on Composite Material Structure is Almost Due to Out-of-Plane Force and Weakness

High Out-of-Plane Strength CFRP is Desired Interlaminar Tension Failure

Induced Interlaminar Tension Failure Under compression

Interlaminar Tension Failure

Induced Interlaminar Tension Failure Under compression

Various Interlaminar (Flatwise) Tension Failures

Peal Stress Figure of Spar Structure

Peak Stress

Skin

Spar

Michael C.Y. Niu, Composite Airframe Structure, ISBN 978-962-7128-11-3


Damage Tolerance of Composite Material

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Catastrophic failure due to fatigue, environmental effect, manufacturing defect, or accidental damage will be avoided throughout the operational life of the aircraft.(AC20-107B)

BVID: Barely Visible Impact Damage

Tool Stone Hail

Manufacturing defect

Not to see the damage from outside

Difficult to predict crack progress

NO CRACK GROWTH


SIP – IMASM 2016

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Delamination or inter-layer crack is the most critical to strength

Smaller damage tend to work as precursor of delamination

Damage Type and Criticality

http://ams.me.kyoto-u.ac.jp/research2006/tf.htm

(Noh et al., 2003)

Fiber/matrix debond Matrix Crack Delamination

• No harm to strength at this stage

Link-up Create

• No great harm to strength at this stage

• Slight stiffness reduction

• Cause significant strength reduction especially in compression and out-of-plane loading

(Bull, 2014)

1 μm 100 mm 100 μm






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Need more detailed observation of damage in micro scale • Complicated propagating behavior due to the heterogeneity and various constituents

involved

• Damage hard to visually recognize until the last minute unlike metals

Damage modeling to follow the observation • To clarify which mechanism makes the most significant contribution to the growth

• To aid selection of material constituents leading to superior damage growth resistance while reducing try-and-error



SIP – IMASM 2016


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Damage observation utilizing X-ray computed tomography (CT) • Powerful for identifying internal micro and macro damage in 3D compared to

conventional techniques

• Combination of a lab CT and synchrotron CT proved to be effective

• In-situ observation of damage growth possible by incorporating a loading unit

(Garcea et al., 2014)

(Shen et al., 2012)


SIP – IMASM 2016


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Studies by Southampton Univ. using synchrotron CT • Spatial resolution less than 1 micrometer using synchrotron radiation

• Assess thermoplastic particle toughening effect on delamination growth under impact

(Images from Bull, 2014)

20 μm


SIP – IMASM 2016

Modeling of Inter-layer Damage Growth

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To find key attributes for inter-layer damage growth resistance • Crack deflection

• Crack bridging

• Crack tip blunting

• Particle/matrix debonding

• Particle plastic deformation

(Images from Bull., 2014)

To assess microstructural parameters associated with the particles • Elastic properties

• Size

• Volume fraction

• Interfacial strength

• Residual stresses


SIP – IMASM 2016

Improving Damage Growth Resistance

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Selection of more effective toughening particles • Optimization and control of particle geometry, concentration and properties

Further toughening of matrix epoxies • Thermoplastic blending

• Dispersing carbon nanotubes

• Forming interpenetrating network

• etc.

• More interactions between interfaces to be involved and controlled, demanding characterization and measurement down to nanoscale

• Increase in material cost needs to be justified

(Petrie, 2006)

(Grimsley, 2015)


SIP – IMASM 2016

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Interface between carbon fiber and matrix epoxy • Primary (covalent) bond or secondary bond?

• Work by BMW to indirectly prove the presence of covalent bond via sizing agent

?

+

160 C

(Wetjen et al., 2015)

Nanoscale Characterization: Example

OH O

Fiber surface activation and Sizing Solvent wash Detect sizing remained on the fiber

Carbon fiber Sizing

R R’

Epoxy 1 Epoxy 2


SIP – IMASM 2016

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Phase separation • Matrix epoxy including thermoplastic polymer as secondary domain

• Imaging of the phase separation would help validate modeling of the resin constitutive properties in atomistic level

(Childers and Tucker., 2015)

(Neaspec GmbH)

Nanoscale Characterization: Example

Activity of SIP A11 unit

© 2016 MITSUBISHI HEAVY INDUSTRIES, LTD. All Rights Reserved. 14

• A/C Cured CFRP • High Toughness (High Out-of-Plane Strength) • High Productivity

(SIP-SM4I brochure）

<Target>

<Partner> • Toray • KHI • FHI • MHI


SIP – IMASM 2016

Summary

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Application of composites to aircraft structures has been expanded over the last decades and forecasted to grow owing to their superior strength and durability One of the keys to promote the application to aircraft is to improve resistance to inter-layer damage growth and thereby out-of-plane strength for ensuring weight advantage over current metallic structures Microstructure of composites make the damage growth behavior rather complicated; More accurate observation and understanding of internal microscopic damage is the first step for further improvement of those performances

Combining the observation with a modeling method to assess the most contributing micro-mechanisms, further improvement of CFRP performance is expected

Nanoscale characterization of interfacial properties should be more focused to quantify both physical and chemical interaction


SIP – IMASM 2016

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Thank you for your attention !

This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion

Program (SIP), “Structural Materials for Innovation” (Funding agency: JST).

Acknowledgments

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