+
Figures taken from:
P.K. Mallick. Fiber-Reinforced
Composites, Materials,
manufacturing, and design. 3rd
Ed., CRC Press. 2008
Introduction to
composites - fibers
CME/MSE 404G. Polymeric Materials
Fall 2012
fibers
+
fibers
2
+
fibers
3
+
fibers
4
+
fibers
5
+
fibers
6
+
fibers
7
+
fibers
8
+
9
Properties of commercial fibers
fiber
D, mm
g/cmt
Et, GPa
Yt, GPa
%
strain
COTE
Poisson
’s ratio
average values from manufacturers
E-glass
10
2.54
72.4
3.45
4.9
5
0.2
S-glass
10
2.49
86.9
4.3
5
2.9
0.22
PAN,
T300
7
1.76
231
3.65
1.4
-0.6
0.2
Pitch,
P55
10
2.0
380
1.90
.5
-1.3
NA
Kevlar
49
11.9
1.45
131
3.62
2.8
-2
NA
Spectra
900
38
0.97
117
2.59
3.5
NA
NA
fibers
+
10
Fibers: 2012
references; new research on fibers for composites
%
#
168
121
54
38
38
30
29
23
20
17
17
17
16
15
13
13
13
12
11
11
10
fibers
24.5%
17.6%
7.9%
5.5%
5.5%
4.4%
4.2%
3.4%
2.9%
2.5%
2.5%
2.5%
2.3%
2.2%
1.9%
1.9%
1.9%
1.7%
1.6%
1.6%
1.5%
material
carbon
silicon carbide
graphite
aluminum
silicon
copper
aluminum oxide
polypropylene
silica
zirconium oxide
titanium
tungsten
polyethylene
pearlitic steel
zirconium carbide
titania
polyacrylonitrile
nickel
molybdenum
silver
titanium carbide
+
In-class exercise
fibers
11
+
12
Each team is to find composites
applications for their fibers
#
fibers
%
168
121
54
38
38
30
29
23
20
17
17
17
16
15
13
13
13
12
11
11
10
24.5%
17.6%
7.9%
5.5%
5.5%
4.4%
4.2%
3.4%
2.9%
2.5%
2.5%
2.5%
2.3%
2.2%
1.9%
1.9%
1.9%
1.7%
1.6%
1.6%
1.5%
material
carbon
silicon carbide
graphite
aluminum
silicon
copper
aluminum oxide
polypropylene
silica
zirconium oxide
titanium
tungsten
polyethylene
pearlitic steel
zirconium carbide
titania
polyacrylonitrile
nickel
molybdenum
silver
titanium carbide
team
007
banana slugs
dream team
effervescent nostrils
Group 5
grulkinators
half n half
pink flamingos
team spiderman
x-factor
day late
x-factor
team spiderman
pink flamingos
half n half
grulkinators
Group 5
effervescent nostrils
dream team
banana slugs
007
assignments
+
13
#
%
168
121
fibers
material
24.5% carbon
17.6% silicon carbide
team
007
banana slugs
54
38
7.9% graphite
5.5% aluminum
38
5.5% silicon
dream team
effervescent
nostrils
Group 5
30
4.4% copper
grulkinators
29
23
20
4.2% aluminum oxide
3.4% polypropylene
2.9% silica
half n half
pink flamingos
team spiderman
17
17
2.5% zirconium oxide
2.5% titanium
x-factor
day late
17
silk
2.5% tungsten
day late
x-factor
16
15
2.3% polyethylene
2.2% pearlitic steel
team spiderman
pink flamingos
13
1.9% zirconium carbide half n half
13
13
12
1.9% titania
1.9% polyacrylonitrile
1.7% nickel
11
1.6% molybdenum
grulkinators
Group 5
effervescent
nostrils
dream team
11
1.6% silver
banana slugs
10
1.5% titanium carbide
007
applications
aerospace, wind turbines,…
structural components - IC engines,
aerospace, fusion
graphite epoxy - space applications
wall panels, replace Au, Ag in yarns
textiles, photovoltaics, rechargeable
batteries
brake pads, linings, high friction
applications
fiber FP, ultrasound lasers, nextel 610
microcracks in concrete
thermal shock, turbine blades, asbestos
substitute, optical fibers
coating in connectors for optical fibers
bone implants M-M- composites, flameresistant paper?
biomedical engineering, drug delivery
W fiber copper composites - heat sinks,
high stress applications
fishing line, orthodontics, yachts
reinforced grout, high impact gray cast
iron
in carbon composites, ablation - wear at
high T, space craft
pigment additive, photocatalysts
aircraft, yachts, sporting goods
mitigate electronic interference, integrated
strain gage, conductors
+ nickel, sintered to glass optic fibers,
high resiliency
antibacterial - cellulose composites,
rubber stabilizer
gas turbine engines, airframes
Team responses
+
14
Fiber bundles
Typical fibers have very
small diameters, so that
fiber bundles are used
for ease of handling.
Untwisted = strand, end
(glass & Kevlar fibers);
=tow (carbon fibers)
Twisted = yarn
fibers
+
15
Single fiber test

ASTM D3379 - ASTM D3379-75(1989)e1 Standard Test
Method for Tensile Strength and Young's Modulus for
High-Modulus Single-Filament Materials (Withdrawn
1998)

A single filament is mounted along the centerline of a slotted
tab using adhesive at each end

The tab ends are gripped in the tensile machine and the
midsection is cut

Constant loading rate until failure
fibers
+
16
Single fiber mounting for tensile
test
fibers
+
17
Tensile property determinations

fibers
Definitions

Fu – force at failure

Af = average filament cross-sectional area (planimeter
measurement via photos of filament ends

Lf = gage length

C = true compliance (via loading rate)
Fu
s fu =
Af
Lf
Ef =
C × Af
Tensile strength
Tensile modulus
+
18
Typical tensile strengths of fibers
Typical fibers have
high strength, high
orientation
Stress-strain curves
are nearly linear up
to failure
Most fail brittlely
Most fibers are prone to
damage with handling
and with contact to other
surfaces
fibers
+
19
Model for fiber tensile strengths
fibers
+
20
Model application
fibers
+
21
Typical applications:
Weibull distribution

Time to failure: failure rate is proportional to time raised to
the nth power, k=n+1

Cases

0 < k < 1: failure rate decreases with time. Example = infant
mortality or early failure of electrical circuits

k = 1: failure rate is constant over time. Example = random
external events

fibers
k > 1: failure rate increases with time. Example = aging process
+
22
Weibull: probability density
In-class question:
Interpret each
curve with respect
to a time-to-failure
data set.
Hint: the integral of
each curve = 1.
fibers
+
23
Weibull: cumulative distribution
In-class question:
Interpret each
curve with respect
to a time-to-failure
data set.
Hint: the upper
limit of each curve
= 1.
fibers
+
24
Failure rates
5
failure rate
4
3
k=0.5
k=1
k=1.5
k=5
2
1
0
0
1
2
Time
fibers
3
+
25
Quantile plots
fibers
+
26
Figure 2.4
fibers
+
27
Example data: failure strength at a
given fiber length
fibers
+
28
Weibull distribution
fibers
+
fibers
29
+
30
Quantile plots
Modmor data
3
data quan les
2
1
0
-1 5
-2
-3
6
7
8
Modmor model
Modmor data
-4
-5
fibers
9
ln(Tensile strength)
10
+
31
Problem 2.5. Mallick

fibers
MSE 599 P2_5.xlsx
+ Analysis of flaws in high-
strength carbon fibres from
mesophase pitch
Janice Breedon Jones, John Barr, Robert Smith, J. Materials Sci., 14,
(1980), 2455-2465
fibers
32
+
33
Data taken at two guage
lengths, 20 mm and 3.2
mm
fibers
+
34
Effect of gauge length on strength
why should there be an effect?
fibers
+
fibers
35
+
fibers
36
+
fibers
37
+
fibers
38
+
39
Single mode of failure should show
similar Weibull plot slopes
Similar slope
suggests the
same failure
modes for
each gauge
length
fibers
+
40
Extrapolate to 0.3 mm length
expected load transfer length for multifilament fibres of this
diameter (3.8 Gpa)
If the failure
mechanisms are
similar, we can
extrapolate the
tensile strength
to shorter gauge
lengths,
estimating the
tensile strength
for lengths that
are difficult to
measure
experimentally.
fibers
Flaw strength distributions and
+ statistical parameters for
ceramic fibers: the normal
distribution
M. R’Mili, N. Godin, J. Lamon, Phys. Rev. E, 85, 051106 (2012)
Large sets of ceramic fibre failure strengths from tows of 500 – 1000
filaments
Flaws generated by ultrasonic
Flaw strengths are distributed normally
fibers
41
+
42
SiC-based
Nicalon
filaments
fibers
+
43
Quasi-linear regression
failure of fiber tows
For probabilities
less than 4%, there
is an underestimate of the
number of first
failures. This is
likely due to the
detection of low
energy events
near the filtering
threshold.
This is probably
not a bimodal
distribution of
flaws.
fibers
+
44
Comparison of model and fiber
failure data
Very good indeed.
fibers
+
45
General effect of aspect ratio on
tensile strength
fibers
+
46
Dry glass bundle. 3000 filaments
Single filament shows a linear
stress-strain curve.
Bundle shows a nonlinear
stress-strain curve prior to
maximum stress, and
progressive failure after
maximum stress.
Both effects are due to statistical
distribution of the filament
strengths. Some fail as the load
increase. After the maximum
stress, highly loaded fibers
continue to fail, but not all at
once
fibers
+
Fiber production
Glass fibers
fibers
47
+
fibers
48
+
49
Types of glass fibers
tensile strength = 3.45 GPa; surface flaws reduce this to 1.72
GPa

Continuous strand roving [strand = parallel filaments, n >
204]

Woven roving [roving = group of untwisted strans/ends
wound on a cylindrical forming package]

Chopped strands – continuous strands cut to specific lengths;
3.2 – 12.7 for injection molding

Chopped strand mats - 50.8 mm for chopped strand mats

Woven roving mat

Milled glass fibers, 0.79 to 3.2 mm; plastic fillers
fibers
+
fibers
50
+
fibers
51
+
fibers
52
+
fibers
53
+
fibers
54
+
fibers
55
+
fibers
56
+
fibers
57
+
58
Glass fiber compositions
fibers
+
59
Glass fiber properties
fibers
+
60
Sizing chemistries
fibers
+
fibers
61
+
fibers
62
+
fibers
63
+
fibers
64
+
fibers
65
+
Boron fibers
fibers
66
+
fibers
67
+
fibers
68
+
Boron Fiber
http://specmaterials.com/boronfiber.htm
69
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Specialty Materials, Inc.
BORON FIBER
Produced in single-filament reactors by Chemical Vapor Deposition (CVD), boron fiber exhibits a
unique combination of High Strength, High Modulus and Large Diameter.
Boron Fiber Properties
Boron Prepreg Tape
Prepreg Properties
Hy-Bor® Prepreg Tape
Hy-Bor® Prepreg Tape Properties
Hy-Bor® Properties vs Standard Preforms
Boron Compression Strength Analysis
Hy-Bor® Fiber Count and Compression Strength
Compression Strength After Impact for Hy-Bor®
Elemental boron is deposited on a fine tungsten wire substrate and produced in diameters of 4.0-mil
(102-micron) and 5.6-mil (142-micron).
The resulting fiber is essentially amorphous boron with a fully borided-tungsten core.
The textured surface provides an excellent interface in resin-matrix composites, eliminating any need for
sizing treatments.
Primarily used in resin-matrix composites it is available as a unidirectional prepreg tape with 250ºFand
350ºF cure epoxies.
home | about us | products | applications | use & safety | contact us | directions | site map | press
SPECIALTY MATERIALS, INC.
1449 Middlesex Street Lowell, Massachusetts 01851
Phone: 978-322-1900 • Fax: 978-322-1970
Email:info@specmaterials.com
fibers
Unidirectional Dry Woven Boron
Boron Fiber Neutron Shielding Properties
+
70
http://www.angelfire.com
Boron Fibers
Boron is an inherently-brittle material. It is commercially made by chemical
vapor deposition of boron on a substrate, that is, boron fiber as produced is
itself a composite fiber. In view of the fact that rather high temperatures are
required for this deposition process, the choice of substrate material that
goes to form the core of the finished boron fiber is limited. Generally, a fine
tungsten wire is used for this purpose. A carbon substrate can also been
used. The first boron fibers were obtained by Weintraub by means of
reduction of a boron halide with hydrogen on a hot wire substrate.
The real impulse in boron fiber fabrication, however, came only in 1959 when
Talley used the process of halide reduction to obtain amorphous boron fibers
of high strength. Since then, the interest in the use of strong but light boron
fibers as a possible structural component in aerospace and other structures
has been continuous, although it must be admitted that this interest has
periodically waxed and waned in the face of rather stiff competition from
other so-called advanced fibers, in particular, carbon fibers.
fibers
+
71
synthesis
Reduction of boron Halide : Hydrogen gas is used to reduce boron trihalide:
2BX3 + 3 H2 = 2 B + 6 HX where X denotes a halogen: Cl, Br, or 1.
In this process of halide reduction, the temperatures involved are very high, and, thus,
one needs a refractory material, for example, a high melting point metal such as
tungsten, as a substrate. It turns out that such metals are also very heavy. This process,
however, has won over the thermal reduction process despite the disadvantage of a
rather high-density substrate (the density of tungsten is 19.3 g cm -3) mainly because
this process gives boron fibers of a very high and uniform quality. There are many
firms producing boron fibers commercially using this process.
In the process of BCI3, reduction, a very fine tungsten wire (10-12 micron diameter) is
pulled into a reaction chamber at one end through a mercury seal and out at the other
end through another mercury seal. The mercury seats act as electrical contacts for
resistance heating of the substrate wire when gases (BCl3, + H2,) pass through the
reaction chamber where they react on the incandescent wire substrate. The reactor
can be a one- or multistage, vertical or horizontal, reactor. BCl3 , is an expensive
chemical and only about 10% of it is converted into boron in this reaction. Thus, an
efficient recovery of the unused BCl3, can result in a considerable lowering of the
boron filament cost.
fibers
+
Kevlar
fibers
72
+
fibers
73
+
fibers
74
+
fibers
75
+
fibers
76
+
fibers
77
+
fibers
78
+
fibers
79
+
fibers
80
+
fibers
81
+
fibers
82
+
83
Carbon fibers
Graphitic orientation
a. Circumferentially
orthotropic
b. Radially orthotropic
c. Transversely isotropic
d. Circumferential +
radial
e. Circumferential +
random
fibers
+
84
Carbon fibers
In-class question: the
most common
orientation for pitch
fibers
Graphitic orientation
a. Circumferentially
orthotropic
b. Radially orthotropic
c. Transversely isotropic
d. Circumferential +
radial
e. Circumferential +
random
fibers
+
fibers
85
+
Filament failure under
compression
fibers
86
+
87

Compression failure cannot be determined directly by
simple compression tests on filaments

Indirect methods are used, such as the loop test, in which a
filament is bent into a loop until it fails.

The compressive strength is determined from the
compressive strain at the fiber surface.
fibers
+
88
Fiber compressive strength
fiber
Tensile strength,
GPa
Compressive
strength, GPa
E-glass
3.4
4.2
PAN T-300
3.2
2.7-3.2
AS4 carbon
3.6
2.7
GY-70 carbon
1.86
1.06
P100 carbon
2.2
0.5
Kevlar 49
3.5
0.35-0.45
Boron
3.5
5
fibers
+
89
Effect of fiber diameter on
strength
Explain this phenomena
fibers
+
90
Effect of fiber diameter on
strength
Fiber that are formed by spinning
processes usually have
increased strength at smaller
diameters due to the high
orientation that occurs during
processing.
fibers