Innovative Leichtbauwerkstoffe auf Kunststoff- und ... · PDF fileFatigue Behavior of CFRP/Blind Rivet Nut Hybrid Compounds Load amplitude F a Displacement amplitude s a Number of

1Innovative Lightweight Materials on Polymer and Wood Basis as Instigators of MobilityFrank Walther | 26.10.2014

Innovative Lightweight Materials on Polymer and Wood Basis as Instigators of Mobility – Looking Backward and Forward

Prof. Dr.-Ing. Frank Walther

Materials Test Engineering (WPT), TU Dortmund University

Innovative Leichtbauwerkstoffe auf Kunststoff- und Holzbasis als Impulsgeber der Mobilität – Rückblick und Ausblick


1. Introduction

Scientific Areas


Carbon Fiber Reinforced Plastics (CFRP)

Laminates Hybrid Structures

Vulcanized Fiber Wood

Wood Wood-Plastic-Composites (WPC)

Measurement Techniques

AcousticEmission

Fiber-Bragg-Grating-Sensors

Fundamentals Applications

1. Introduction

Innovative Lightweight Composites and Hybrid Compounds


2. Testing Systems

Mechanical and Corrosion Labs


2. Testing Systems

Mechanical Lab

Universal Testing Systems AGS-X and AG-X

5kN … 250kN

Thermostatic Chamber TCLHumidity Chamber TCH

ServopulserL-type (20kN) Micro-Magnetic

Testing System MMT-500 (500N)

Ultrasonic Fatigue Testing System USF-2000 (20kHz)

ServopulserU-type (100kN)


3. Measurement and Testing Methods

Research Qualifications



Sensor Systems

mechanical

thermal

electrical

acoustical

magnetic

optical

Extensometer

Thermocouples

Thermocamera

Direct current

Alternating current

Barkhausen noise

Ferritescope

GMR

Digital image correlation

Mechanical vibration / Acoustic emission


Fatigue life

Str

ess

amp

litu

de

August Woehler (1819 - 1914)

Shipton, 1874

Eschede, 1998 Cologne, 2008

Linz, 1875

Demerits:- Only total life is considered- No information about failure mechanism- Extensive testing (time, costs !)

Shortcomings ? Intelligent accelerated testing ! Basis for process design / understanding,

life cycle evaluation


Woehler Curve



Short-Time Load Increase Procedure – Staircase or „Cyclic Tensile Test“

Material reaction:Material reaction:and

and

RAPID (Rapid Fatigue Performance

Identification Method)


Wood(Beech, Spruce)

Wood Plastic Composites(WPC)

Vulcanized Cotton Fiber(Vulkanfiber)

4. Results

Innovative Lightweight Products Made of Vulcanized Fiber, Wood and WPC


Young's modulus Tensile strengthMaximum

strain

Highhumidity 30% 40%

Lowhumidity

Ideal for forming processes

After drying original properties(reversibel process)

4. Results

Influence of Humidity on Mechanical Properties of Vulcanized Fiber


Speed [mm/min] 1 5 10 100 1.000 3.000 720.000 900.000 1.200.000

Young's modulus[MPa]

8.264 8.461 8.865 9.288 15.651

Tensile strength[MPa]

101 106 110 115 124 128 130 145 161

Maximum strain[%]

6,78 7,28 7,04 7,12 5,96

High strain rate: Increase in strength ~ 60%

4. Results

Influence of Strain Rate on Mechanical Properties of Vulcanized Fiber

HITS-T

HPV-1/-2


4. Results

Tensile and Fatigue Properties of Timber and Timber Structures


Beech

Spruce

WPC (50% PVC/50% wood)

WPC (25% PE/75% wood)

4. Results

Influence of Strain Rate on Tensile Deformation of Vulcanized Fiber, Wood and WPC


Beech

Spruce

WPC (50% PVC/50% wood)


4. Results

Influence of Humidity on Tensile Deformation of Vulcanized Fiber, Wood and WPC


Beech

Spruce

WPC (50% PVC/ 50% wood)


T1

T2

T3

4. Results

Fatigue Behavior of Vulcanized Fiber, Wood and WPC


0°glued 10° 90°

Specimen Geometry

• DIN EN ISO 527-2:2012

• Flat tensile specimen

0°

Fiber Orientation

0°

10°

90°

Glued joint

• Hysol 9492 (epoxy resin adhesive)

• Glass balls to control joint gap

4. Results

Fiber Orientation and Geometry of Beech Wood


Pyrometer

• Contactless operation

∆T = Tspecimen - Tambient

Thermocouples

• Fixed with tape

- Influencing the structure- Results vary widely

T2

T1

T3

Used

Thermocouples

• Fixed with wood glue

- Fixation dissolves

T2

T1

T3

∆T = T2 - 0.5 (T1+T3)∆T = T2 - 0.5 (T1+T3)

4. Results

Temperature Measurement of Beech Wood Under Fatigue Loading


• 0° and 10° are similar (90-100%)

• 90° has lowest stress amplitudes (8-12%)

• Glued joints show stress amplitudes of 87-88% of 0°

Average of 3 tests in each category

4. Results

Comparison of Stress Amplitudes for Beginning of Damage and Fracture

25

46


• Construction of Woehler curves based on tensile and single step tests

• Further tests to define endurance limit

4. Results

Influence of Fiber Orientation on Woehler Curves


Side view Top view

Rear view

Glass balls

• 0.4 mm diameter

Adhesive layer

Fracture surface

Wood fiber structure

Source: Prof. Kaloudis, University of Applied Sciences Aschaffenburg, 2013

4. Results

CT Investigations on Glued Beech Wood Specimens


4. Results

Fatigue Behavior of CFRP/Blind Rivet Nut Hybrid Compounds

CFRP

Blind Rivet Nut


C-Fibre G-Fibre Steel

E-Modul [GPa]

~230 86 ~210

Density[g/cm3]

1.80 2.54 ~7.85

CFRP

4. Results


Blind Rivet Nut

head

shaft

formed part

threaded part


N

sa

Fa Fa

sa

∆sa = sa,max - sa,min

Fa

sa

4. Results


Load

ampl

itude

Fa

Dis

plac

emen

tam

plitu

des a

Number of cycles N (x 104)

Load amplitude Fa

Cha

nge

in d

ispl

acem

ent

s a


CFRP/Aluminium

CFRP/Stainless Steel

4. Results

Corrosion Behavior of CFRP/Aluminium and CFRP/Steel Compounds


4. Results

Intrinsic Hybrid Structures

Steel: Isotropic High Density (7.85 g/cm³) Young`s Modulus 210 GPa

CFRP: Anisotropic Low Density (1.5 g/cm³) Young´s Modulus ǁ 150 GPa

Hybrid Structures: Combination of steel and CFRP Optimization of the component regarding

mechanical load Reinforcement by CFRPWeight reduction

Source: LiA, Paderborn

Source: LiA, Paderborn


4. Results

Intrinsic Hybrid Structures


Industry

Cooperation Partners

„Teaching and Research are of great importance, but as a

progressive department we`re moreover a Partner of the Industry

for developing and implementing real tasks and analysis.“


Universal Testing Systems AGS-X and AG-X

5kN … 250kN

Thermostatic Chamber TCLHumidity Chamber TCH

ServopulserL-type (20kN) Micro-Magnetic

Testing System MMT-500 (500N)

Ultrasonic Fatigue Testing System USF-2000 (20kHz)

ServopulserU-type (100kN)Stand 8b / H16

Industry

Cooperation Partners


TU Dortmund UniversityFaculty of Mechanical EngineeringDepartment of Materials Test EngineeringProf. Dr. Frank WaltherBaroper Str. 303D-44227 Dortmund (Germany)

Phone: +49 (231) 755 8028Fax: +49 (231) 755 8029Email: [email protected]: www.wpt-info.de

QUESTIONS?

Innovative Leichtbauwerkstoffe auf Kunststoff- und ... · PDF fileFatigue Behavior of CFRP/Blind Rivet Nut Hybrid Compounds Load amplitude F a Displacement amplitude s a Number of

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