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High Temperature Composites

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Mechanical properties of carbon and glass composites. Hybrid composites: carbon/glass and ... Strain at peak load (ductility) Density. All glass: 2.36 g/cm3 ... – PowerPoint PPT presentation

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Title: High Temperature Composites


1
High Temperature Composites
  • Rutgers University
  • Federal Aviation Administration
  • Advanced Materials Flammability
  • Atlantic City, NJ
  • October 24, 2001

2
Research Team
  • P. Balaguru
  • J. Giancaspro
  • C. Papakonstantinou
  • R. Lyon (FAA)

3
Introduction
  • Polysialate (Geopolymer)
  • Aluminosilicate
  • Water-based, non-toxic, durable
  • Resists temperatures up to 1000C
  • Curing temperature 20, 80, 150C
  • Protects carbon from oxidation

4
Ongoing Research at Rutgers
  • Mechanical properties of carbon and glass
    composites
  • Hybrid composites carbon/glass and
    inorganic/organic
  • Structural sandwich panels
  • Comparison with other high temperature composites

5
Hybrids Fiber Characteristics
  • Glass Economical, larger fiber diameter
  • Carbon Higher modulus and strength, durability

6
Variables
  • Eglass fiber core with carbon fiber skins
  • Number of layers on tension side 1,2,3
  • Type of carbon fabric 1k and 3k woven, 3k
    unidirectional
  • Number of layers on the compression side 1,2,3
  • Specimen thickness 6, 12, and 18 layers of
    glass fabrics

7
Specimen Preparation
  • Hand impregnation
  • Room temperature (20C) curing
  • 1 MPa of pressure for 24 hours
  • Post curing for 3 weeks
  • Room temp. curing reduces degradation of glass
    under alkali environment

8
Test Setup
  • Simply supported
  • 3-point bending (ASTM D790)
  • Loading rate 2.5 mm / min

9
Mechanical Properties
  • Load deflection response converted to stress
    and strain
  • Stress,
  • Strain,

10
Assumptions for Analysis
  • Homogeneous
  • Elastic
  • Uncracked section
  • Perfect bond between glass and carbon layers

11
Glass / Carbon Hybrid Results
  • Density
  • Failure pattern
  • Peak stress (strength)
  • Strain at peak load (ductility)

12
Density
  • All glass 2.36 g/cm3
  • All carbon 1.9 to 2.0 g/cm3 for 3 types
  • Increase in carbon layers provide consistent
    decrease in density

13
Failure Pattern
  • Glass brittle, no post-cracking strength
  • Glass with 1 and 2 carbon layers failed in
    tension
  • Glass with 3 carbon layers compression failure
  • Glass with both tension and compression
    reinforcement compression failure

14
(No Transcript)
15
3k Unidirectional Carbon
16
Samples with 2 Carbon Layers
17
Varying Sample Thickness
18
Maximum Stress 3k Uni Carbon
  • Pure Glass 103 MPa
  • Glass 1 Layer 212 MPa
  • Glass 2 Layers 379 MPa
  • Glass 3 Layers 354 MPa
  • 3k Unidirectional Carbon 466 MPa

19
Thickness vs. Maximum Stress
  • 6 Glass 1 carbon (uni) 347 MPa
  • 12 Glass 2 carbon 379 MPa
  • 18 Glass 3 carbon 362 MPa

20
Maximum Strains
  • Matrix (tension) 0.0007
  • Matrix (compression) 0.005
  • All Glass (tension) 0.003

21
Maximum Strain 3k Uni Carbon
  • Pure Glass 0.003
  • Glass 1 Layer 0.007
  • Glass 2 Layers 0.011
  • Glass 3 Layers 0.009
  • 3k Uni Carbon 0.005

22
Thickness vs. Maximum Strain
  • 6 Glass 1 carbon (uni) 0.012
  • 12 Glass 2 carbon 0.011
  • 18 Glass 3 carbon 0.011

23
Conclusions Glass/Carbon Hybrids
  • Eglass / carbon is a viable combination.
  • For all types of carbon fabric, 2 layers on the
    tension side provides the highest strength.
  • Placing carbon on both compression and tension
    faces does not significantly increase the
    strength.

24
Conclusions Glass/Carbon Hybrids
  • Eglass reinforced with 1, 2, or 3 carbon layers
    exhibited the highest strength when the fabric
    was 3k unidirectional
  • Slightly lower strengths were achieved using 3k
    woven carbon fabric
  • The lowest strengths were achieved using 1k woven
    carbon fabric

25
Conclusions Glass/Carbon Hybrids
  • The uncracked section modulus for Eglass
    reinforced with 1k or 3k woven on the tension
    side showed little change as the number of carbon
    layers increased.
  • 3k unidirectional carbon on the tension side
    provided a modulus increase with an increasing
    number of layers.
  • An increase in modulus also results for carbon on
    both compression and tension sides.

26
Strain Capacity of Polysialates
  • Cantilever Beam Method

27
Variables Investigated
  • Silica / Alumina ratio
  • Discrete carbon fiber content
  • Effect of ceramic micro-fibers

28
Influence of Carbon Fiber Content on Cracking
Strain
29
Effect of Microfibers
Without Ceramic Microfibers
With Ceramic Mircofibers
30
Durability
  • Wet-Dry
  • Flexure
  • 45 In-Plane Shear
  • Thermo-mechanical
  • Exposure Temperatures (200, 400, 500, 600C)

31
Wet Dry Durability
32
Comparison of Polysialate and Other Inorganic
Composites
  • Relative performance of polysialate composites
  • Processing requirements
  • Mechanical properties
  • Carbon/Carbon composites
  • Ceramic matrix composites
  • Carbon/Polysialate composites

33
Stress vs. Strain Relationships of Bi-directional
Composites in Tension
34
Tensile Strength of Bi-directional Composites
35
Flexural Strength of Unidirectional Composites
36
Flexural Stress-Strain Relationships of
Unidirectional Composites
37
Flexural Strength of Bi-directional Composites
38
Lightweight Sandwich Panels
  • Core features
  • - Inorganic matrix ceramic spheres
  • - Density 0.6 to 0.7 g/cm3
  • - Compressive strength 5.12 MPa
  • Carbon fabric laminated onto facings

39
Typical Section of Sandwich Slab (Panel)
  • Lightweight ceramic core
  • Carbon facings on both tension and compression
    sides

40
Flexural Strength of Slabs With Different
Reinforcement
41
Load vs. Deflection for Slabs
42
Future Research
  • Commercially available plates Inorganic
    matrix layer
  • Glass plates
  • Carbon plates
  • Fatigue
  • Sandwich panels
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