0 5 10 15 20

0 10 20 30 40 50 60

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

Failure Stress, τult

(MPa)

Percent Cohesive Failure, Acoh

Ran

king

Par

amet

er, P

Hε

τ = 0.5τult

Acoh

τult

Employing a variety of data anlaysis methods creates a rich understanding of a material system. Strain map mining reveals details of strain distribution that relate microstrucure to strain evolution (N). Finite element modeling complements experimental work and aids in interpretation of experimental data (O). Comparisons between strain maps and failure statistics (P) can also be used to create charasteristic parameters and numerical models that predict material behavior i.e. failure strength and type of failure (Q).

P

Q

N

O

0 1.3 3.9 5.2

5.2

6.52.6Relative X Location (mm)

Rel

ativ

e Y

Loc

atio

n (m

m)

Rel

ativ

e Y

Loc

atio

n (m

m)

7.8 9.1 10.4 0 1.3 3.9 5.2 6.52.6

Relative X Location (mm)

7.8 9.1 10.4 0 1.3 3.9 5.2 6.52.6Relative X Location (mm)

7.8 9.1 10.4

0

1.3

3.9

6.5

2.6

7.8

9.1

5.2

0

1.3

3.9

6.5

2.6

7.8

9.1

5.2

0

1.3

3.9

6.5

2.6

7.8

9.1

Rel

ativ

e Y

Loc

atio

n (m

m)

εyyεyyεyy

Normalized crack length l/w

Stre

ss σ

(MPa

)

σc = 60 MPaBefore convergenceAfter convergence

Papers are complex polymer fiber-based composite systems which are finding new uses in energy-absorbing structures, portable medical diagnostic tools, and more. Because paper is a non-affine discontinuous material, paper defies conventiontional mechanical characterization. In addition to basic mechanical characterization and post-fracture analysis (I), we use specialized strain mining techniques. These include application of spatial statistics to strain maps (J) and direct analysis of the displacement fields (K). We also use various types of imaging techniques (L: SEM, CSLM) to characterize the structure of these complicated iber networks.

300 µm

2.0 mm

IJ

L

Primary Fiber Orientation

Transverse Displacement

Axial Displacement

Shear Strain

J

100 µm

100 µm

K

Lorem ipsum

1.0 mm

Thin metal sheets (µm and nm scale) exhibit interesting size-dependent properties and fracture mechanisms due to the plane stress stress state, surface effects, out of plane deformation, etc. We explore the fracture characteristics 25 µm thick Al (E), evaluate metal systems using customized test systems and strain map analysis techniques such as path integrals (F & G), and illustrate zones of deformation (H).

E

G F

FPZ

ZAP

ZAP

Rigid

Rigid

H

C

Thin flexible materials have countless cutting-edge applications: Flexible substrates for electronics, displays, or portable medical diagnostic tools: skins and control surfaces for ultra-light flying robots; or as components of laminate composites for packaging, optics, and more. The Muhlstein Group at GA Tech studies the mechanical characteristics of thin flexible sheets. Our work in-cludes mechanical testing with optical strain measurement (A), thin sheet processing (B and C), and apparatuses and analyses built around the unique challenges of working with thin flexible systems (D).

B

A

D

Thin flexible sheets Thin metal sheet fracture and fatigue

Nonwoven fiber networksFailure prediction from strain fields

The Muhlstein Research Group

200

400

600

800

1000

200

400

600

800

1000

Fatigue Fracture

Flexible Forms