Micro-Fatigue Testing in Metallic Material

Important to use Accelerated Fatigue Test (AFT)

method to be able to save time and cost.

Modal Shaker DMA

Initial

Design

Existing 3-point

(Clamped) Design

Existing 3-point

Design

Improved 3-point

(Clamped) Design

Run Fatigue

Test using

DMA

13023NName: Uvarajan M Velayutham

UoG Matriculation No: 2059265S

1st Supervisor (in Singapore): Dr Christian Della

2nd Supervisor (in Glasgow): Prof William Sloan

Industry Supervisor: Dr Ronnie Teo

Micro-Fatigue Testing

in Metallic MaterialIntroduction

Aims and Objectives

a Development of AFT method using Modal Shaker

Conclusion

Conventional fatigue testing is very time consuming

and expensive.

Conventional fatigue testing machines have several

limitations.

This research aims to investigate the use of Modal Shakers

and Dynamic Mechanical Analyzers (DMA) for AFT, and the

objectives are :

a. Develop a novel AFT method using Modal Shaker.

b. Design a fixture assembly for AFT using both DMA &

Modal Shaker.

c. Improve existing DMA 3-point fixture, through analysis

and fatigue tests.

Complete system assembly for AFT using both

Modal Shaker and DMA systems :

Conventional

Fatigue Tester

Modal Shaker

(M1600W)

DMA

(Q800)

Testing

FrequencyLow High High

Loading

AmplitudeHigh High Low

Thermal

Control

1) Specimen

Preparation

Grinding

Polishing

Etching

2) Fixture

Mounting

Clamp

Calibration

3) Test

segments

Equilibrate

at 30˚C

Frequency

sweep at

100Hz for

100000

cycles

4) Microscopic

Analysis

Observe

for Micro-

cracks

formation

5) Nano-

indentation

Record

material

property

changes

during

fatigue

process

The novel fixture assembly can be used for AFT using both

Modal Shaker and DMA.

Project Workflow

Modal

Shaker

Dynamic

Mechanical

Analyzer

(DMA)

Fixture assembly (A) and rig (B) have been designed for

Modal Shaker based on first/fundamental design principles.

Rounded contact surfaces has reduced the stress concentration at

the support regions in the Improved 3-point (Clamped) design.

Improved 3-point (Clamped) Design:

Existing 3-point (Clamped) Design:

Initial Design:

Existing 3-point Design:

Running Fatigue Test using DMA:

Cyclic 3-point test in

DMA using existing

3-point design

Initial

Design

Existing 3-Pt

Design

Existing 3-Pt

(Clamped)

design

Improved 3-Pt

(Clamped)

design

Contact type Rounded Rounded Flat Rounded

Syst

em

Co

mp

ati

bil

ity Modal

Shaker

DMA

This developed AFT method can significantly reduce fatigue

testing time and cost.

References[1] Escobar, L.A, Meeker, W.Q, 2006. A review of accelerated test modals. Statistical Science, No.4,

pp. 552-577.

[2] Farrar, C.R, Duffey, T.A, Cornwell, P.J, & Bement, M.T, 1999. A review of methods for

developing accelerated testing criteria. In Proc. of the 17th International Modal Analysis

Conference, Kissimmee, FL, pp. 608-614.

[3] Sujan E. Wadud, 2012. Improvements in DMA Measurements Using Low-Friction 3-Point

Bending Clamps. TA Instruments.

[2, 3]

[1]

Critical points at corners

Flat contact

surface of clamp

Rounded contact

surface of clamp

T E S T S P E C I M E N

Fixture A

Rig B

c Improvement through test: A preliminary study

b Improvement through analysis

STRESS MAX

7.9 MPa

STRESS MAX

6.1 MPa

T E S T S P E C I M E N

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