Novel NDT Approaches for Adhesive Composite Bonds · Testing Technology Rudolf Henrich Head of Testing Technology Germany for Adhesive Composite Bonds Background & Objectives •

DACH-Jahrestagung, 28.-30.04.2008

Presented by

Novel NDT Approaches

Dr. Clemens BockenheimerTesting Technology

Rudolf HenrichHead of Testing Technology Germany

ppfor Adhesive Composite Bonds

Background & Objectives

• Performance of adhesive bonds after manufacturing and in-service is ensured by design, control of materials & processes and NDT

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• Adhesive bonding of composites offers new fields of beneficial application

• A potential enabler in this connection are novel methods of NDT

* Performance of Adhesive Bond

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Dr. Clemens Bockenheimer, DACH-Jahrestagung 2008 Page 2

= Required Functionality + Durability

Co-bonding of A380 VTP Structure

DACH-Jahrestagung 2008 in St.Gallen - Mi.1.A.3

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Performance Adhesive Bond – Influencing Factors

PropertiesPropertiesLoadingLoading

Source: Dr. Bockenheimer,Dr. Valeske, ZFP of Adhesive Joints, EAE Qualification Course, IFAM Bremen, 2007

In-Service

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Adhesion, Cohesion

Network Structure

Molecular Mobility

Adherents

D fD f

Physical

Mechanical

LoadingLoading

ChemicalPerformance

Adhesive Bond

Interphases

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Delamination

DefectsDefects

Processing& Manufacturing

In-ServiceDebonding

Pores...

...

Performance Adhesive Bond – Quality Insurance

Control of Materials& Processes

Design Adhesive BondCuring Process Surface Teatment Process

Adhesive / ResinAdherents

Source: Dr. Bockenheimer,Dr. Valeske, ZFP of Adhesive Joints, EAE Qualification Course, IFAM Bremen, 2007

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Properties

Defects

LoadingPerformance Adhesive

Bond

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• Performance of adhesive bond ensured by design, control of materials & processes, NDT

• Today: NDT is applied for the detection of defects only

NDT

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NDT of Adhesive Bonds – New Approach

Control of Materials& Processes

Design Adhesive BondCuring Process Surface Teatment Process

Adhesive / ResinAdherents

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Properties

Defects

LoadingPerformance Adhesive

Bond

Source: Dr. Bockenheimer,Dr. Valeske, ZFP f Adh i J i t

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New Approach: ‘Novel NDT Methods‘ ‘Novel NDT Methods‘ for the determination of selected physical-chemical properties of the adhesive bond

NDTNDT ZFP of Adhesive Joints, EAE Qualification Course, IFAM Bremen, 2007Novel NDT

Novel Methods of NDT - Adherent

Adherent:Adherent: Determination of selected physical-chemical properties(+ molecular mobility) Statements regarding…

• Surface treatment quality (prerequisite for formation of adequate adhesion)

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• Inner and outer contamination (release agents, kerosene, hydraulic fluids, …)

• Ageing Processes (chemical and physical ageing)

• Damages (lightning strike, overheating, …)

CFRP Adherente.g. Contaminatione.g. Contamination

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InterphaseInterphase

BulkBulk

CFRP Adherent


Molecular Molecular NetworkNetwork

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Novel Methods of NDT – Adhesive Joint

Adhesive Joint:Adhesive Joint: Determination of selected physical-chemical properties(+ molecular mobility) Statements regarding…

• Compound Strength (governed by adhesion, cohesion, network structure,

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interphases)

• Network Structure (especially cross-linking density)

• Thermo-Mechanical Properties (mechanical moduli, glass transition, …)

• Ageing Processes ( h i l d h i l i )

AdhesionAdhesion

CohesionCohesion

Adhesive JointAdhesive Joint

CFRPCFRP

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(chemical and physical ageing)

Molecular Molecular MobilityMobility

CFRPCFRP


BulkBulk


Novel Methods of NDT – Potential Approaches

Potential ‘Novel NDT’ Methods Potential ‘Novel NDT’ Methods (for the measurement of selected chemical-physical properties)

Technology Probe & Interaction Degree of Information

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Nuclear Magnetic Resonance (NMR)

Alternating magnetic field interacts with spins of the

adhesive atoms

Molecular Mobility: Degree of Curing, Moduli, Inhomogeneties,

Ageing/Degradation

Dielectric Spectroscopy

(DES)

Alternating electric field interacts with electrical dipoles

of the adhesive

Molecular Mobility: Degree of Curing, Moduli, Ageing/Degradation

Multi Frequency Eddy Current

T ti

Alternating electric field interacts with electrical dipoles

f th dh i

Molecular Mobility: Degree of Curing, Moduli, Ageing/Degradation

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Testing of the adhesive Moduli, Ageing/Degradation

Tera-Hertz (Radar Technology)

Electro-magnetic waves interacts with polymer micro-

structure (diffraction, scattering, attenuation)

High Resolution Microscopy for CFRP bonds (compared to conventional micro-

wave techniques)

continued

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Novel Methods of NDT – Potential Approaches

Continued

Technology Probe & Interaction Degree of Information

Shock Excitation M th d

High intensity mechanical wave is probing adhesion and It is ensured that the adhesive bond has a

i i h i l f

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Methods is probing adhesion and cohesion minimum mechanical performance

Infrared Microscopy (IR)

IR beam interacting with molecular vibration modes Chemical composition of adhesive

Micro Differential Scanning

Calorimetry (DSC)

Heat flow interacting with phonons of the adhesive

moleculesGlass transition / Degree of Curing

Micro Dynamic Mechanical Analysis

(DMA)

Dynamic mechanical loading interacting with molecular

mobility

Glass transition / Degree of Curing, Mechanical Modulus,

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(DMA) mobility

Mechanical Induced Thermography

Interaction of stress and strain field with phonons of adhesive

molecules (local hysteresis excitation)

Detection of weak boundary layers

Surface Characterisation

Methods

Chemical or physical probe interacts with chemical or physical surface states

Chemical and physical state of the composite surface

...

Novel Methods of NDT – Basic Requirements

• Simple handling• Universal application targets• Robustness

ManufacturingManufacturing

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• Quick data evaluation• Detection capability• Large inspection range• Low cost• In-service application / bonded repair

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Availability for maintenance shopsHandheldRuggedness

• ...InIn--ServiceService

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Novel Methods of NDT – Example AdherentAdherent

Infrared (IR) Spectroscopy: A2 Technologies, handheld

ance

ance

Source: A2 Technologies

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Abs

orba

Abs

orba

IR Reference IR Reference SpectraSpectraIR AbsorbanceIR Absorbance

SpectraSpectra

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BulkBulk



Molecular Resonance AbsorptionMolecular Resonance AbsorptionChemical CompositionChemical Composition

• Contaminations • Surface Treatment Quality• Ageing Processes

Interaction VolumeInteraction Volume

Novel Methods of NDT – Example

Magnet

Source: Dr. Bockenheimer, Dr. ValeskeZPF von Klebverbunden,EAE Qualifikationskurs, IFAM Bremen

Off-set handheld NMR: IZFP Saarbrücken


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Spule

Magnet

Magnetic Field B0HF Fi ld B

Spin density, Relaxation times TSpin density, Relaxation times T11, T, T22

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HF-Field B1Sensitive Volume)Overall Measurement RangeSample

Molecular MobilityMolecular Mobility• Degree of curing • (Thermo-) mechanical properties (glass transition, fracture toughness, ...)

• Characterisation of bondline and CFRP (inhomogenities, ...)

• Ageing Behaviour (absorption, plasticitation, physical ageing/brittleness, ...)

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Novel Methods of NDT – Example

3 5DSC: 52 % Aushärtung

Example: Curing of Araldit 2014 Example: Curing of Araldit 2014 Process ControlProcess Control

Degree of Curing


Off-set handheld NMR: IZFP Saarbrücken

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7

9

11

13

15

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Ein

[V]

2

2,5

3

3,5

E/S H

Ein

[V/V

]

DSC: 52 % Aushärtung g g

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3

5

7

0 50 100 150 200 250 300Aushärtungszeit, t A [min]

Spin

S HE

u

1

1,5 S S

Source: Dr. Bockenheimer, Dr. ValeskeZPF von Klebverbunden,EAE Qualifikationskurs, IFAM Bremen

Curing Time / min.

Conclusion

• Conventional NDT (defect detection) plays a major role in order to ensure performance of adhesive composite joints

• Adhesive bonding of composites offers new fields of

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Adhesive bonding of composites offers new fields of beneficial application

• A potential enabler in this connection are novel methods of NDT for the determination of selected physical-chemical properties – promising approaches are available

• Collaborations and partnerships are needed to develop

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• Collaborations and partnerships are needed to develop solutions for industrial applications !

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Documents

Novel NDT Approaches for Adhesive Composite Bonds · Testing Technology Rudolf Henrich Head of Testing Technology Germany for Adhesive Composite Bonds Background & Objectives •