Process-Property Relationships in Ultrasonic Additive ... s SS tube Cu Al Complex Internal Cooling...

Eighth Annual Meeting, Honda R&D, 20-21 Aug 2015

Professor: Dr. Marcelo Dapino

Acknowledgements:

• NSF I/UCRC Program, SVC IAB

• NSF Graduate Research Fellowship Program

• Ohio Third Frontier Wright Project

Process-Property Relationships in

Ultrasonic Additive Manufacturing of

Lightweight Structures

Adam Hehr

[email protected]

Department of Mechanical and Aerospace Engineering

The Ohio State University


Talk Overview

• Ultrasonic Additive Manufacturing- UAM

• Bond Formation in UAM

• Welder Energy and Parameters

• Effect of Build Compliance on Effective Weld Power

• Power Compensation

• UAM Process Modeling

• Concluding Remarks


Ultrasonic Additive Manufacturing - UAM• Recent technology that combines:

Ultrasonic metal welding

Additive manufacturing

CNC machining center

• Low temperature process:

Interface near ½ Tmelt

Measureable temp near 100 oC for

Al 6061-H18 [1]

• Enabling technology for dissimilar

metal joining and low temperature

applications

[1] M. Sriraman, M. Gonser, H. Fujii, S. Babu and M. Bloss, "Thermal transients during processing of materials by very high power ultrasonic additive

manufacturing," Journal of Materials Processing Technology, vol. 211, p. 1650– 1657, 2011. 3


UAM Video

4


NiTi Al

Smart Materials

Integration

Al

Fiber Optic Cable

PVDF in Al

Embedded Temperature Sensitive Sensors

and Electronics

Al

Carbon

Fiber

Al

Ti

Light-Weighting with Dissimilar

Materials and Metals

Alum

inumFib

er

Op

tic

s

SS tube

Cu

Al

Complex Internal

Cooling

Solid-State ActuationMulti-Material Joints and ReinforcementEfficient Cooling and Embedded Sensing

Flu

id f

low

pump

heater

cooling

thermo-

couple

Automotive Aerospace

http://jwst.nasa.gov/www.dolphin.fr

UAM Applications and Strengths


Bond Formation in UAM

• Recent advancements in delivered power and down force have remedied interface

voids, i.e. gapless structures [2]

• Weld microstructure is composed of recrystallized small (~1 micron) equiaxed

grains within narrow region of weld interface (~ 20 micron) [3-4]

• The degree of recrystallization is foretelling of the shear strain at the interface due

to dynamic recrystallization being a function of (i) strain and (iii) temperature [5]

6

Bulk Tape

Bulk Tape

Mixing

New

Grains

New

Baseplate

Grains

Baseplate

Original Baseplate

Grain Boundary

Bulk Tape

New Tape

Grains Mixing

New Baseplate

Grains

Welded Layers

Baseplate

[2] K. Graff, M. Short and M. Norfolk, "Very High Power Ultrasonic Additive Manufacturing (VHP UAM)," in International Solid Freeform Fabrication Symposium, Austin, 2011.[3] K. Johnson, "PhD Thesis: Interlaminar Subgrain Refinement in Ultrasonic Consolidation," Loughborough University, 2008.[4] R. Dehoff and S. Babu, "Characterization of interfacial microstructures in 3003 aluminum alloy blocks fabricated by ultrasonic additive manufacturing," Acta Materialia, vol. 58, pp. 4305-4315, 2010. [5] F. Humphreys and M. Hatherly, Recrystallization and Related Annealing Phenomena, Elsevier, 2004.


Welder Energy and UAM Parameters

• Controllable Parameters:

Vibration amplitude, δ (μm, % of max)

Normal force (N)

Sonotrode travel speed, Vt (in/min)

Baseplate temperature (°F)

• Fixed Parameters:

Vibration frequency (~20 kHz)

Sonotrode roughness (~7 or 14 micron Ra ) and material (tool steel)

Tape thickness (~0.006”)

• Typical weld power for Al 6061-H18 is near 2-3 kW

• Typical weld power for as rolled 4130 steel is near 5-7 kW

7

𝐸𝑤𝑒𝑙𝑑 = 𝑃 ∙ 𝑑𝑡 =1

𝑉𝑡 𝐹 ∙ 𝜔 ∙ 𝛿 ∙ 𝑑𝑥


Effect of Build Compliance on Effective Weld Power

• Build compliance refers to the mechanical deformation of the part when subjected

to shear force during the UAM process – compliance increases with part height [6]

• Build compliance leads to a decrease in plastic deformation, i.e., a decrease in

effective weld power

• Power compensation achieved by increasing weld amplitude manually

8

0 5 10 15 20 2560

70

80

90

100

110

120

No. of Welded LayersPe

rce

nt A

ve

rag

e E

lectr

ic P

ow

er

(W/W

)

UncompensatedCompensated

Fs

UAM Stack

with keff

stiffness

Baseplate

New Layer

Imparted amplitude

Amplitude lost to

compliance

25% power loss

Amplitude available

to weld foil

[6] A. Hehr, P. Wolcott and M. Dapino, "Effect of Weld Power and Build Compliance on Ultrasonic Consolidation," Rapid Prototyping Journal, In Press.


Power Compensation

9

• Does power compensation lead to stronger welds?

• Approach:

Measured weld power for compensated and uncompensated stack builds

Push-pin testing to evaluate bond strength

Focused Ion Beam (FIB) imaging used to analyze interface

microstructure

0 5 10 15 20 25 30

400

600

800

1000

1200

1400

1600

Uncompensated Power

Weld Length (cm)

We

ld P

ow

er

(W)

Layer 2

Layer 5

Layer 10Layer 15

Layer 20

0 5 10 15 20 25 30

400

600

800

1000

1200

1400

1600

Compensated Power

Weld Length (cm)

We

ld P

ow

er

(W)

Layer 2

Layer 5

Layer 10

Layer 15

Layer 20

0 5 10 15 20 25800

900

1000

1100

1200

1300

1400

1500No. Layers vs. Steady-State Avg. Power

Number of Welded Layers

Ave

rag

e P

ow

er

(W)

Uncomp.Compensated


Power Compensation: Push-Pin Testing

• Comparative test

• Used to evaluate UAM

interfacial bond strength

• Successfully used in

recent Al 6061-H18 weld

study [7].

10

F

Base plate

Notch

Width

3-4 Layers

Thick

Base Plate

Plus 5-6

Layers Deep

20 Total

Layers

UAM Build

“Good”“Poor”

0 0.5 1 1.5 2 2.5 3 3.50

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Stroke [mm]

Fo

rce [kN

]

Energy Compensated

Uncompensated

Similar Peak Load

Enhanced Mechanical Work

Interface

Delamination

Delaminationf

Failure Thru All

the Layersf

CompensatedUncompensated

[7] P. Wolcott, A. Hehr, M.J. Dapino, “Optimized welding parameters for Al 6061 ultrasonic

additive manufactured structures,” Journal of Materials Research 29 (17).


Power Compensation: Weld Microstructure

11

Uncompensated: Layer 15

Unmixed zone

Uncompensated: Layer 5 Compensated: Layer 5

Compensated: Layer 15

• Enhanced interface recrystallization with power compensation


Power Compensation: Energy Balance

• Energy balance can be utilized to analyze bonding process

• Eplastic measured remotely via transducer power consumption (Eweld)

• Erecryst measured via quantity of new small grains at interface [8]

• Stronger welds achieved with larger Erecryst due to Hall-Petch

relationship [8]

• First time weld microstructure has been correlated with energy

input

12

𝐸𝑠𝑢𝑟𝑓 + 𝐸𝑝𝑙𝑎𝑠𝑡𝑖𝑐 = 𝐸𝑏𝑢𝑙𝑘 + 𝐸𝑟𝑒𝑐𝑟𝑦𝑠𝑡 + 𝐸𝑡ℎ𝑒𝑟𝑚𝑎𝑙Input Output

[8] R. Abbaschian, L. Abbaschian and R. E. Reed-Hill, Physical Metallurgy Principles, Stamford: Cengage Learning, 2010.


UAM Process Modeling: LTI Model

13

Welding

Assembly𝑒𝑙𝑒𝑐𝑡𝑟𝑖𝑐 𝑐𝑢𝑟𝑟𝑒𝑛𝑡: 𝑖𝑠ℎ𝑒𝑎𝑟 𝑓𝑜𝑟𝑐𝑒: 𝐹𝑠

𝑉𝑜𝑙𝑡𝑎𝑔𝑒: 𝑉𝑤𝑒𝑙𝑑 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦: 𝑗𝜔𝛿

𝑰𝒏𝒑𝒖𝒕𝒔 𝑶𝒖𝒕𝒑𝒖𝒕𝒔𝑳𝒊𝒏𝒆𝒂𝒓 𝑺𝒚𝒔𝒕𝒆𝒎

𝑗𝜔𝛿𝑉

=𝐻𝑒𝑚∗ 𝐻𝑒

∗

𝐻𝑚∗ 𝐻𝑚𝑒

∗𝑖𝐹𝑠

𝑳𝑻𝑰 𝑴𝒐𝒅𝒆𝒍

𝛿

Fs

Piezo

Compression Rod

Actuator 1

V

Actuator 2

V

Sonotrode

𝑖 𝑖

V

Ct

Mt1:Φt

𝛿Φt 𝛿𝑖

Φt 𝑉

1/KtDt

Fs

Lumped System: Welder Characterization

V

1/Mt

Ψt:1

𝛿𝑖 Ψt 𝛿

Kt 1/Dt

FsΨt𝑖

Lumped System: Welder Operation

• Electroacoustics theory [9-12]

[9] B. Richter, J. Twiefel, J. Wallaschek, Energy Harvesting Technologies: Ch4: Piezolectric Equivalent Circuit Models, Springer, 2009.[10] W. P. Mason, Electromechanical Transducers and Wave Filters, D. Van Nostrand Company, Inc., 1942[11] F. Hunt, Electroacoustics: The Analysis of Transduction and Its Historical Backaground, Cambridge: Harvard University Press, 1954.[12 C. van der Burgt, H. Pijls, Motional Positive Feedback Systems for Ultrasonic Power Generators, IEEE Transactions on Ultrasonics Engineering 10 (1)


UAM Process Modeling: Characterization

• Shear force: High frequency modal hammer

• Weld velocity: Laser vibrometer

• Voltage and current: Linear amplifier

• Frequency response functions: Quattro analyzer

• Boundary conditions: In UAM machine

14

Welding

Assembly

Laser Vibrometer

PowerAmplifier

Charge

Amplifier

Quattro

Analyzer

Analysis

Computer


UAM Process Modeling: Model Fit

• Good agreement with measured and closed form FRFs

• Fit procedure found in literature [9]

15

19.6 19.7 19.8 19.9-38

-36

-34

-32

-30

-28

-26

Frequency (kHz)

He d

B M

agnitude (

A/V

)

Exp.

Fit

19.6 19.7 19.8 19.9-70

-60

-50

-40

-30

Frequency (kHz)

Hem

dB

Magnitude (

m/s

/V)

19.6 19.7 19.8 19.9-80

-70

-60

-50

-40

-30

Frequency (kHz)

Hm

dB

Magnitude (

m/s

/N)

19.6 19.7 19.8 19.920

40

60

80

100

120

Frequency (kHz)

He P

hase A

ngle

(deg)

19.6 19.7 19.8 19.9-100

-50

0

50

100

Frequency (kHz)

Hem

Phase A

ngle

(deg)

19.6 19.7 19.8 19.9-150

-100

-50

0

50

100

Frequency (kHz)

Hm

Phase A

ngle

(deg)


UAM Process Modeling: In-Situ Measurements

LTI model assumption valid?

• Yes, welder dynamics are pseudo-stable during operation

• Measurements support model assumptions

16

0 0.5 1

19.7

19.75

19.8

19.85

Weld

er

Fre

quency (

kH

z)

Time (s)

0 0.5 11.7

1.75

1.8

1.85

1.9

1.95

2

Peak V

elo

city (

m/s

)

Time (s)

No Welding

Welding

Peak Weld Velocity Welder Frequency

0 0.5 10

200

400

600

800

1000

Avera

ge E

lectr

ic P

ow

er

(W)

Time (s)

Electric Power Draw

40 50 60 70 801

1.5

2

2.5

3

Pe

ak V

elo

city (

m/s

)

Amplitude Level (%)40 50 60 70 80

0

100

200

300

400

Ave

rag

e E

lectr

ic P

ow

er

(W)

40 50 60 70 80600

700

800

900

1000

1100

1200

1300

1400

Amplitude Level (%)

Pe

ak V

olta

ge

(V

)

(a)

40 45 50 55 60 65 70 75 8050

100

150

200

250

300

350

Amplitude Level (%)

Ave

rag

e E

lectr

ic P

ow

er

(W)

Power Calibration

Measured

Estimate

Adj. Estimate

Welder VoltageWelder Velocity and Power


UAM Process Modeling: Shear Force and Efficiency

• Shear force near 2000 N, which is similar to de Vries [13].

• Welder efficiency near 82%, which is near ultrasonic metal welding

estimates [14] and below piezoelectric transducer efficiency [15].

• Upward frequency shift from UAM build stiffening system.

17

0 0.5 119.75

19.8

19.85Excitation Frequency

Weld

er

Fre

quency (

kH

z)

Time (s)

0 0.5 11.6

1.7

1.8

1.9

2Peak Weld Velocity

Peak V

elo

city (

m/s

)

Time (s)

0 0.5 1

0

500

1000

1500

2000Peak Shear Force

Peak F

orc

e (

N)

Time (s)

0 0.5 10

500

1000

1500

2000Weld Power

Avera

ge E

lectr

ic P

ow

er

(W)

Time (s)

No Welding

Welding

𝑖

𝑖𝑟𝑒𝑓=

𝑃

𝑃𝑟𝑒𝑓

𝐹𝑠 =𝐻𝑒𝑚∗ 𝑖 − 𝑗𝜔𝛿

𝐻𝑚∗

𝑒 =𝑗𝜔𝛿 ∗ 𝐹𝑠

𝑃

∆𝑃 =1

2

V

Ψ𝑡Δ𝐹𝑠

𝑺𝒉𝒆𝒂𝒓 𝑭𝒐𝒓𝒄𝒆 𝑬𝒔𝒕𝒊𝒎𝒂𝒕𝒊𝒐𝒏

𝑬𝒇𝒇𝒊𝒄𝒊𝒆𝒏𝒄𝒚

𝑷𝒐𝒘𝒆𝒓 𝑪𝒐𝒏𝒕𝒓𝒐𝒍 𝑳𝒂𝒘

[13] E. de. Vries, Mechanics and Mechanisms of Ultrasonic Metal Welding, Ph.D. thesis, The Ohio State University, Columbus, OH, USA (2004).[14] K. Graff, AWS Handbook 9th Edition: Volume3: Ultrasonic Welding of Metals, American Welding Society, 2001.[15] R. Friel, Power Ultrasonics: Ch13: Power ultrasonics for additive manufacturing and consolidation of materials, Elsevier, 2015.


Conclusion

• UAM enables fabrication of unique materials and products

• Weld power/energy correlation with bond quality

• Weld power as an in-situ process variable

• LTI model which uses shear force as a system input

• In-situ measurements of welder

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Process-Property Relationships in Ultrasonic Additive ... s SS tube Cu Al Complex Internal Cooling...

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