Docstoc

06-ASME Talk low rez 2

Document Sample
06-ASME Talk low rez 2 Powered By Docstoc
					Biomimicked Composites for Fabrication of
     Dynamically Tough Structures


   S. M. Allameh1, T. Ogonec1, M. Sadat Hossieny1
                   and P. Cooper2
              1Department   of Physics and Geology
            2Department   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 years1
        – Last 23 months, disorientate losses   This building was one of many that were
                                                leveled in Ahmedabad, India, during
•     Heavy (solid) structure                   Friday's 7.9 magnitude earthquake. In
                                                Ahmedabad alone, 40 to 50 high-rise
•     Large dynamic shear forces                buildings crumbled.
•     Lack of structural material toughness
•     Natural Solutions exist: Biomimicking

1. World Bank Report
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

                                                                       Crack




                                                       Soft Polymer                   Hard Mineral

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

                                   Fracture
                                   Strength Fracture
Type of Composite                  (MPa)    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                           1.2

  toughness                                 1
                                                     QS-Mono

• Degradation of fracture                            QS/QBA




                            Stress (MPa)
                                           0.8
  strength
                                           0.6
• Apparent Modulus: 130
  MPa                                      0.4


                                           0.2


                                            0
                                                 0        0.01            0.02   0.03
                                                                 Strain
       Effect of Liquid Nail Polymer

• Increase in toughness                    1.2
                                                     QS-Mono


• Degradation of fracture
                                                     QS/LiqNail
                                            1


  strength                                 0.8




                            Stress (MPa)
• Apparent Modulus: 130
                                           0.6


                                           0.4
  MPa
                                           0.2
• Convoluted curve
                                            0

   – Concrete                                    0          0.01
                                                                  Strain
                                                                           0.02   0.03



   – Glue
       Effect of Gorilla Glue Polymer

• Increase in toughness                      2
                                            1.8
                                                      QS-Mono

• 50% increase in fracture                  1.6
                                            1.4
                                                      QS/GorGl




                             Stress (MPa)
  strength                                  1.2
                                             1

• Apparent Modulus: 400                     0.8
                                            0.6
  MPa                                       0.4
                                            0.2
                                             0
                                                  0   0.005      0.01   0.015   0.02   0.025
                                                                   Strain
       Effect of Fiber Glass with Glue
                                           16
• Significant Increase in                  14
                                                    QS-Mono
                                                    QS/FibGls
  toughness                                12

• 1000% increase in




                            Stress (MPa)
                                           10

  fracture strength                         8

                                            6
• Apparent Modulus: 600
                                            4
  MPa
                                            2

                                            0
                                                0     0.02       0.04    0.06   0.08
                                                                Strain
        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
                                                        Si Rich sand
                                    Concrete Layers


                                           Interfacial Bond Layer




                                                      Ca-Rich Matrix

                                    Concrete Layers
                    Slow Set Concrete
• Thickness of hard layer~ 1-2 mm
• Thickness of soft layer ~ mm 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
                                         50
• Composite: ~ 40 MPa                    45       QSC-1
  max compressive                        40       QSM-1
                                         35
  strength
                          Stress (Mpa)
                                         30

• Monolithic: ~ 5 MPa                    25
                                         20
                                         15
                                         10
                                          5
                                          0
                                              0            0.05        0.1     0.15
                                                          Compressive Strain
                             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
                                      3M Spray Glue
                                                                                             Quikreet Concrete Glue
                    50                                                           50
                    45                                                           45       QSC-1
                             SSC-1
                    40       SSM-1                                               40       QSM-1
                    35                                                           35




                                                                  Stress (Mpa)
     Stress (Mpa)




                    30                                                           30
                    25                                                           25
                    20                                                           20
                    15                                                           15
                    10                                                           10
                    5                                                            5
                    0                                                            0
                         0             0.05        0.1     0.15                       0            0.05        0.1     0.15
                                     Compressive Stgrain                                          Compressive Strain
                         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

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:12
posted:2/22/2012
language:
pages:28