Materials Processing and Manufacturing: Novel Processes and ModelingContact: Prof. Donggang Yao; email: yao@gatech.edu

School of Materials Science & Engineering

Georgia Institute of Technology

School of Materials Science and Engineering

Research Interest: 1. Development of new methods for precision polymer fabrication,

blends processing, composites processing, gel spinning of ultrastrong fibers, and processing of bulk metallic glasses.

2. Constitutive modeling: rheology of immiscible polymer blends, nonlinear viscoelasticity, and deformation at micro/nano scales.

3. Dynamics of materials processing: modeling of non-Newtonian flow, finite-strain deformation, and blend dynamics.

4. Computational materials science: molecular dynamics, finite element analysis, and multiscale simulation.

Selected Processes:• Two-station embossing

• Rubber-assisted micro forming

• Rapid-thermal-response micro injection molding

Rapid heating Embossing Holding/cooling Demolding

Rapidly heated

Forming & cooling Opening Part ejection

Master moldMicro formed film

Rubber

Preheating

Selected Parts/Structures:

100

100μ 50μ

• Micropatterning of porous structuresHot embossing

Sacrificial extraction& formation of porous

patterns

Co-continuous blending

A

B

• Extrusion roll-to-roll micro/nano imprinting

p

T1

T2

T3

Imprinting zoneR2

R1

R3

Film Direction

Induction Heating

Pressure Rollers

Belt Mold

60

80

100

120

140

160

180

200

0 5 10Time, seconds

Tem

pera

ture

, °C

H.F. in H.F. out

B

Stationary half

Moving half

CDE

FGH

IA

• Gel spinning of ultra-strong fibers

Constitutive Modeling:

Deform

Deform

Oriented phase structure Non-orientedNon-oriented

• Nonlinear viscoelasticity with a microstructure tensor

daVV

a nnIIT33

2

')''(:)(0

1

0

daVJU

nnCF

BB

IT AA 2

Dynamics of Polymer Processing:

200µm 50µm 25µm 5µm

25µm50µm100µm200µm

Depth:

We acknowledge the financial support from NSF under Awards 0238033, 0503138, 0620668, 0637784, 0712305, 0800016, 0826259, 0848524, 0927697, 1462101, 1927651, and 2027871, as well as support and partnership from industrial partners and sponsors.

Acknowledgements

R2

R1

R3

R4Cold

WarmHot

Coagulation bath

Wind up Roll

Rollers

Spinhead

Polymer solution

Gellation

Precursor Drawing & heat treatment

Heated rolls

High-performance fiber with E > 150 GPa and > 4.5 GPa

←  

T 

Gradient structures

0.1

1

10

100

1000

10000

1 10 100 1000

Rhe

olog

ical

Pro

perti

es

N1, predicted in Pa(-N2), predicted in Pa, predicted in Pas

BIT

BBB

)/1(

ln)/1(

1

00

00

SSGp

SS

• Plastic processing of metallic alloysBulk metallic glasses

Nonisothermal embossing

Noncircular fiber spinning Injection molding

Extrusion

Micro-thermoforming

Blends processing

• Novel extrusion and fiber spinning processes