Biomimicked Composites for Fabrication of Dynamically Tough Structures

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29 Νοε 2013 (πριν από 3 χρόνια και 4 μήνες)

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Biomimicked Composites for Fabrication of
Dynamically Tough Structures

S. M. Allameh
1
, T. Ogonec
1
, M. Sadat Hossieny
1

and P. Cooper
2

1
Department of Physics and Geology

2
Department of Construction Management

Northern Kentucky University

Highland Heights, KY 41076

Outline of Presentation


Motivation


Background


Experimental Details


Preliminary Results


Discussion


Future Work

Motivation


Earthquakes, Tornados, Hurricanes


Fatalities


2 million up to 1970s


400,000 in last 23 months


Property Damages


2004: $B629 for last 20 years
1


Last 23 months, disorientate losses


Heavy (solid) structure


Large dynamic shear forces


Lack of structural material toughness


Natural Solutions exist: Biomimicking




1. World Bank Report

This building was one of many that were
leveled in Ahmedabad, India, during
Friday's 7.9 magnitude earthquake. In
Ahmedabad alone, 40 to 50 high
-
rise
buildings crumbled.

Nature’s Solutions to Nature’s Problems


Examine Nacre: hard brittle layers sandwiched in soft
polymer


Crack changes its plane when it interacts with soft layer


Structure of Abalone can be mimicked

Soft Polymer

Hard Mineral

Structure of Nacre with hard inorganic layers glued
together by soft polymer phase. Crack changes its
plane when propagating leading to interlocked
interdigitating half plates that maintains the integrity

Crack

Naturally occurring tough shell of
Abalone

Integration of Biomimicking and Robotics


Toughens otherwise brittle ceramic


Lightens up heavy structures


Use of lattice block, sandwich structures


Fabrication of aerodynamic/intricate designs


Shortens fabrication time


Lessens reliance on human factor


Allows fabrication in hazardous, toxic, hostile
environments

Role of Robotics


Robots allow on
-
site manufacturing of composites


Biomimicked structures


Reinforced composites


harsh environments


More reliable


intricate shapes, hollow geometries, Incorporation of
insulation, plumbing, wiring cavities

Experimental Procedure


Type of concrete


Type of Polymer


Proportions


Layering Process

Material


Quikrete Quick setting Cement, #
1240 (20
-
44 MPa Compressive
Strength)


Quikrete Concrete Bonding
Adhesive #9902 (0.7
-
1.0 MPa)


Liquid Nail Glue LN
-
275


Benzene based synthetic rubber


0.8
-
2 MPa shear strength


Gorilla Glue polymer:


70% Urethane prepolymer


30% Polymeric MDI


Fiberglass (Interwoven)

Layering of Samples


Used dog bone shape samples,


100 mm in length


25 mm in width and thickness


Al mold


Instron used to elevate the
mold for layering


Manual spread of concrete, 5
min to mix and spread


20
-
60 min laps allowed drying
of glue


Layer thickness: 1.2
-
1.5 mm

Tensile Specimens Made


Monolithic


Composite of Quikrete and


Liquid Nail


Cement Bonding Adhesive


Gorilla Glue


Fiber Glass + Gorilla Glue

Details of Layers


QS + Fiber Glass + Gorilla Glue


Composite of QS + Liquid Nail

Mechanical Testing Setup


Dog Bone Shape Samples


Instron load Frame used


Strain rate: 2.5 x 10
-
4

Results

Type of Composite

Fracture

Strength

(MPa)

Fracture
Strain

Monolithic

1.1

0.008

Fiber Glass/G. Glue Composite

14.9

0.03

Concrete Bonding Adhesive

0.58

0.012

Gorilla Glue Composite

1.82

0.01

Liquid Nail Composite

0.84

0.025

Effect of Concrete Bonding Adhesive


No Increase in
toughness


Degradation of fracture
strength


Apparent Modulus: 130
MPa

0
0.2
0.4
0.6
0.8
1
1.2
0
0.01
0.02
0.03
Strain
Stress (MPa)
QS-Mono
QS/QBA
Effect of Liquid Nail Polymer


Increase in toughness


Degradation of fracture
strength


Apparent Modulus: 130
MPa


Convoluted curve


Concrete


Glue

0
0.2
0.4
0.6
0.8
1
1.2
0
0.01
0.02
0.03
Strain
Stress (MPa)
QS-Mono
QS/LiqNail
Effect of Gorilla Glue Polymer


Increase in toughness


50% increase in fracture
strength


Apparent Modulus: 400
MPa

0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0
0.005
0.01
0.015
0.02
0.025
Strain
Stress (MPa)
QS-Mono
QS/GorGl
Effect of Fiber Glass with Glue


Significant Increase in
toughness


1000% increase in
fracture strength


Apparent Modulus: 600
MPa

0
2
4
6
8
10
12
14
16
0
0.02
0.04
0.06
0.08
Strain
Stress (MPa)
QS-Mono
QS/FibGls
Fractography of Specimens


Monolithic



QBA composite



Gorilla Glue
Composite



Fiberglass Composite



Liquid Nail Composite

Crack Initiation and Propagation


Liquid Nail Composite

Preliminary Results


Structures were made from caulk with robots
dispensing the material


Biomimicked samples were made by layering of
concrete and two types of glues


Quikrete concrete mix + Quikrete concrete glue


Quikrete concrete mix + 3M Spray glue


Characterization of microstructure performed


Mechanical tests were performed

Characterization of Quick Set Concrete


SE and BSE imaging with SEM performed


Elemental dot maps obtained


Details of interlayers observed

Interfacial Bond Layer

Concrete Layers

Concrete Layers

Si Rich sand

Ca
-
Rich Matrix

Slow Set Concrete


Thickness of hard layer~ 1
-
2 mm


Thickness of soft layer ~

m
m range

Mechanical Testing of Samples


Instron test frame used for compression testing


Samples:


Dimension: 1” x 1” x 1” cube


Quikrete Concrete Mix (Hard inorganic layer)


Monolithic


Composite


Glue (soft polymer layer)


Quikrete cement glue

Strength of Biomimicked Composites


Quikrete concrete mix


Quikrete cement glue


Cure 4 weeks


Composite: ~ 40 MPa
max compressive
strength


Monolithic: ~ 5 MPa

0
5
10
15
20
25
30
35
40
45
50
0
0.05
0.1
0.15
Compressive Strain
Stress (Mpa)
QSC-1
QSM-1
Effect of Soft Polymer Layer


Quikrete mortar mix


Quikrete cement glue vs. 3M Spray glue


Cure 4 weeks


Concrete Glue shows significant improvement in compressive strength

0
5
10
15
20
25
30
35
40
45
50
0
0.05
0.1
0.15
Compressive Strain
Stress (Mpa)
QSC-1
QSM-1
Quikreet Concrete Glue
3M Spray Glue
0
5
10
15
20
25
30
35
40
45
50
0
0.05
0.1
0.15
Compressive Stgrain
Stress (Mpa)
SSC-1
SSM-1
Summary


Biomimicked structures were made using cement and polymer


Robotic construction of layered structures were demonstrated


Tensile and compressive specimens were tested


Fractography and microstructural characterization of the
samples carried out by scanning electron microscope


Polymers play an important role in strengthening the
biomimicked composites in both tension and compression


Fiber
-
glass
-
reinforced biomimicked samples showed highest
tensile strength


Crack inanition was observed to start from the corners and
edges


Crack propagation was slow and stopped with the terminated
of the test


Future Work


Implementation of the process (AGVs)


Optimization of material (selection of hard ceramic,
soft polymer)


Mechanical testing (3
-
point bend test, Fatigue test,
dynamic shear tests)


Microstrucatl characterization, fractography


Educational aspects (senior research projects)

Acknowledgment


CINSAM, Dr. Phil Schmidt for financial support


Dr. Patrick Moynahan of financial Support


Mr. Karl Hagglund, for analytical work with SEM