VALIDATION OF FRICTION STIR WELDING PROCESS MODELS of... · 4th International Symposium on Friction...

Dickerson and Shercliff

4th International Symposium on Friction Stir Welding. 1

4th International Symposium on Friction Stir Welding.Park City, Utah, USA, 14-16 May 2003. Page 1

"VALIDATION OF FRICTION STIR WELDING PROCESS MODELS"

CT slice at the weld root of the exit hole of a 2024-T3 weld.

By Terry Dickerson & Hugh

Shercliff


NOTE

This set of slides was made in response to a request by the conference organiser to fill in a vacated position in the conference schedule. The request was made at short-notice which meant there was inadequate time to produce a proper paper. These presentation slides have been included in lieu of a full paper.

Please feel free to contact the author ([email protected]) about the FSW Benchmark, particularly if you want to contribute to it.




RATIONALE

The physics of FSW is complex.To be meaningful, process models of FSW require validation.Validation can be carried out at a number of levels. However, the most significant will be comparison data from real welds.

Answer - produce welds and welding data.


OBJECTIVES

To make the data wide ranging to enable validation on several levels.Make sure the welding set-up was well defined and compatible with modelling.

Produce experimental data for validation of FSW modelling: Some things to think

about when designing FSW experiments:

boundary conditions,tool forces & torque,temperatures,flow visualisation,residual stress measurement,weld sizes etc.




DLR, Cologne, Germany

EXPERIMENTAL: Machine (1)

Converted Milling Machine

Data Acquisition Computers•Positions

•Forces

•Torque

•Temperature

CNC Controller


EXPERIMENTAL: Machine (2)

Machine head

Dynamometer for tool:•Forces and

•Torque

Welding Tool

Backing bar or anvil




Air gap under anvil

EXPERIMENTAL: Anvil

Anvil bolted to machine table

FixturesWelding Tool

Weld panel


EXPERIMENTAL: ThermocouplesThermocouple wires Plugs

Weld panel

* * * ***

Typical thermocouple locations on section

Weld panel

Anvil

Thermocouple buried in anvil

Machine Bed




EXPERIMENTAL: Markers

LongitudinalTransverse centreTransverse end

Annealed copper sheet 0.1mm thick was placed in the weld and then welded through @:

Wel

ding

Dire

ctio

n

150m

m

60mm60mm

Retreatingside

Advancing side

15m

m

105m

m

60m

m


EXPERIMENTAL: Stop Action

At the end of welding the traverse was stopped and the tool unscrewed to freeze-in the material flow patterns. Shown are:

Optical Photograph.

X-ray image showing the marker.




EXPERIMENTAL: Summary

Known boundary conditions.Tool position, including plunge depth.Tool forces and torque – gives heat inputTemperatures at various locations on/in weld panels and in the anvil.Marker materials in the joint

Validation experiments have been designed to give:


RESULTS: Welding Data




RESULTS: Welding DataDMC-E1

-2

0

2

4

6

8

10

12

14

16

18

20

22

0 10 20 30 40 50 60 70 80 90 100 110

Tool Position from Weld Start / [mm]

Tool

For

ces

/ [kN

]

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Wel

d Po

wer

Inpu

t / [W

]W

eld

Hea

t Inp

ut /

[J/m

m]

DMC-E1 FxDMC-E1 FyDMC-E1 FzDMC-E1 Weld Power Input DMC-E1 Weld Heat Input


RESULTS: Welding DataDMC-E3

0

50

100

150

200

250

300

350

400

450

500

-10 0 10 20 30 40 50 60 70 80 90 100 110 120Time / [s]

Tem

pera

ture

/ [ºC

]

0

20

40

60

80

100

120

Tool

Pos

ition

from

Wel

d St

art /

[mm

]

DMC-E3 Ch2DMC-E3 Ch3DMC-E3 Ch4DMC-E3 Ch5DMC-E3 Ch6DMC-E3 Ch7Tool Position




2mm

Metallographic Sections of a weld with marker.

RESULTS: Metallography


RESULTS: Metallography

Metallographic Sections of a weld: top, without marker and bottom, with marker.




RESULTS: 2D X-ray Imaging

X-ray images of a 6mm thick transverse sections of two welds with marker inserts: top, tool on joint-line and bottom, with an off-set.


RESULTS: X-ray Tomography

Computer tomography (CT) models of the welds with marker materials were built-up, an example is shown opposite with the tool position indicated.

θ=0°




RESULTS: X-ray Tomography

Plan view of a tomographicmodel of a weld with marker material in the joint-line. θ=0°

θ=90°

θ=

θ=270°


Root, z=2.75mm

RESULTS: CT Slicing

CT slices through the

tomographic model on various planes.

Middle, z=1.5mm

Top, z=0.25mm




RESULTS: Summary (1)

Global but transient welding inputs – tool forces – tool torque → weld heat inputs– tool deflection → dynamic plunge depth

Transient local data: – temperatures at various locations (inc. anvil)

Extensive validation data is available on a number of levels:


RESULTS: Summary (2)

Material deformation information– metallography– 2D and 3D X-ray techniques.

Welds are suitable and available for– Other metallurgical analyses– residual stress measurement

So what!!!

Validation data is available (continued):




RESULTS: FSW Benchmarks (1)

Some data is to be made available on a copyright but royalty free basis.Published as a website to allow – Wide access– quick and easy up-dating of information

http://www-materials.eng.cam.ac.uk/FSW_Benchmark/– Partial access to June 2003– Full access after June 2003

Data like that shown requires specialist equipment, is time consuming and therefore expensive:


RESULTS: FSW Benchmarks (1)

welds in 2024-T3, 6mm thick.the data is extensiveShould other welds be added?

Currently one set of data on the site




CONCLUSIONS

Welding experiments have been designed to support and validate modelling of friction stir welding.The experiments have produced a wide range of high quality data that enables validation at a number of different levels.Some of this data will be openly available to the FSW community.


ACKNOLEDGEMENTSThe work was supported by the European Community under ‘Competitive and Sustainable Growth’ (1998-2002). Project: “Joining Dissimilar Materials and Composites by Friction Stir Welding”. Contract: G5RD-CT-1999-00090. The authors thank Mr. Frank Palm at EADS (Ottobrunn, Germany) and the technical staff at DLR (Cologne, Germany) for their help with the experiments.The FSW Benchmark has additionally be supported by TWI Limited (Cambridge, UK)




SOME ASSOCIATED WORKS[1] Dickerson T.L., Shi Q-Y. and Shercliff H.R., “Heat flow into

friction stir welding tools”, Proc. 4th Int. Symp. on Friction Stir Welding, Salt Lake City, Utah, USA, May 2003.

[2] Dickerson T.L., “The Friction Stir Welding Benchmarks”http://www-materials.eng.cam.ac.uk/FSW_Benchmark/, Version 0.1 (draft), January 2003 (restricted access until June 2003).

[3] Shercliff H.R. and Colegrove P.A., “Modelling of friction stir welding”, in Mathematical Modelling of Weld Phenomena 6 (eds. H. Cerjak and H.K.H.D. Bhadeshia), Maney Publishing, London, 2002, 927-974.


SOME ASSOCIATED WORKS[4] Dickerson T.L., Shercliff H.R. AND Schmidt H “A weld

marker technique for flow visualization in friction stir welding”, Proc. 4th Int. Symp. on Friction Stir Welding, Salt Lake City, Utah, USA, May 2003.

[5] Shi Q.Y., Dickerson T.L. and Shercliff H.R., “Thermo-mechanical analysis on welding process of aluminium 2024 with TIG and FSW”, Proc. 6th Int. Conf. on Trends in Welding Research, Pine Mountain, Georgia, USA, April 2002.

[6] Dickerson T.L., Shi Q-Y. and Shercliff H.R., “Thermo-mechanical FE modelling of friction stir welding of al-2024 including tool loads”, Proc. 4th Int. Symp. on Friction Stir Welding, Salt Lake City, Utah, USA, May 2003.

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VALIDATION OF FRICTION STIR WELDING PROCESS MODELS of... · 4th International Symposium on Friction...

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