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A glass fiber is a long glass fiber made of glass. During production, thin
threads are drawn from a glass melt and processed into a large the number of
end products.
Glass fibers are used as fiber optic cable for data transmission and
flexible light transport of z. As laser radiation used as a roving or as a
textile fabric for thermal and acoustic insulation, and for glass fiber
reinforced plastics. These are today among the most important construction
materials. They are aging and weather resistant, chemically resistant and
non-flammable. Their high modulus of elasticity is used to improve the
mechanical properties of plastics.
History Of The Glass Fiber
The origin was the ability of glassblowers from the Thuringian Forest to
produce so-called fairy or angel hair as early as the 18th century. First
used only as decoration means, the possibilities of the fibers after the
foundation of a glass factory in the Thuringian Haselbach of Hermann
Schuller were discovered gradually (1896). There spinnable glass filaments
with a precisely defined diameter were produced for the first time, so to
speak, as "rolls". This process was patented in the 1930s as a rod drum
removal process.
Use as a Light Guide
In the fiber direction, light can spread in glass fibers almost unhindered.
By a radially outwardly decreasing refractive index, continuous or gradual,
the light is guided in the fiber. This property as a light guide is used in
many technical applications.
Data Transfer
Glass fibers are used inter alia as optical fibers in fiber optic networks
for optical data transmission. This has the advantage over electrical
transmission of a significantly higher maximum bandwidth. It can be
transmitted more information per unit time. In addition, the transmitted
signal is insensitive to electrical and magnetic interference fields and
offers higher security against eavesdropping.
Lighting, Decoration, Art, and Architecture
In a variety of lamps and lighting installations, glass fibers are used
today, the fibers being used not only for light transport but also as
radiating elements themselves. An unusual application is the production of
translucent concrete: the incorporation of three to five percent of glass
fiber content creates translucent concrete elements through which you can
see light, shadows, and colors up to a wall a thickness of 20 cm.
Illumination and Imaging in Medicine and Metrology
Glass fibers and glass fiber bundles are used for lighting and imaging z. B.
on microscopes, inspection cameras or endoscopes or even with cold light
sources used (see also: fiber optics). In most cases, however, polymeric
optical fibers are used for illumination since they are more flexible and do
not break when overstretched.
Sensors
Glass fibers are increasingly used in metrology. Fiber optic sensors are
used in which the measured variable is not represented or transmitted as
typically by an electrical variable, but by an optical, for data acquisition
in hard to reach areas such as dams or under extreme conditions such as
steelworks or magnetic resonance tomographs. There are two classes of fiber
optic sensors:
Extrinsic:
Here, the glass fiber serves only as a transmitter of the measured variable
detected by the sensor, which the sensor must provide as an optical signal.
Examples are glass fiber pyrometers, fiber optic temperature probes or
optical microphones (fiber optic transducers).
Intrinsic:
Here, the glass fiber serves directly as a sensor and is thus both sensor
and line. Examples are fiber optic pressure sensors, the fiber optic
temperature measurement or the fiber gyro for measuring the angular
velocity.
Laser
Fiber Laser In Double Sheath Fiber Construction
For the flexible transport of laser radiation, glass fibers are used to
direct the radiation on the one hand in the processing of materials and in
medicine to the processing site (cutting, welding, etc.) and on the other in
the measurement, microscopy, and spectroscopy to the sample.
In laser show technology, laser light is directed from a central source via
fiber-optic cables to various projectors distributed throughout the room.
The services here are a few hundred milliwatts up to double-digit wattages.
Laser beams can not only be guided into the glass fibers, but also generated
and amplified in them. To find z. B. Fiber lasers and erbium-doped fiber
amplifiers used in the telecommunications sector. Due to the good efficiency
of the conversion process and the good cooling due to the large surface of
the fiber as well as the very high beam quality, high-performance fiber
lasers are used in material processing and medicine.
Use of Mechanical Properties
- Typical properties of glass fibers
- Density 2.45 ... 2.58 g / cm³
- Filament diameter 5 ... 24 microns
- Tensile strength 1.8 ... 5 GPa (kN / mm²)
- Tensile modulus 70 ... 90 GPa
- Elongation at break <5%
high-performance bundle of glass fibers for plastic reinforcement
(Glasfaserroving)
For mechanical applications, the glass fibers are usually present as
roving, nonwoven or as tissue. For profiles, however, unidirectional
(unidirectional) fibers are used; For example, sports arrows for archery,
rods for insulation or z. B. made in some umbrellas of glass fiber
reinforced plastic.
Since glass fibers are very notch sensitive, they are provided with a
so-called sizing in the production or prior to weaving. This size (eg a
silane size) serves as a lubricant during weaving and is chemically
removed after weaving. Thereafter, the so-called finish is applied to the
glass fibers, which acts as a bonding agent between the glass fibers and
the synthetic resin for use in fiber composites. Finish is also referred
to as an adhesive-containing size. It can make up to two percent by mass
but is usually 0.3 to 0.8 percent.
Glass fiber reinforced plastics show only a very low tendency to creep and
absorb only very little moisture.
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Strength
The high strength of the glass fiber is based on the size influence. Due
to the fiber shape, the defect size in the fiber is smaller than in the
compact material volume. At the same time, the defect-free length in the
fiber form increases. As a result, the strength of the glass fiber
compared to the compact material is greater.
The the tensile and compressive strength of the glass fiber ensures a
special stiffening of the plastic while maintaining a certain flexibility
thanks to the (compared to steel) high elastic elongation at break. The
properties of glass fibers are used, for example, in the manufacture of
high-strength and lightweight components such as sports boats, GRP
profiles, GRP reinforcements or fishing rods. Tanks and pipes for highly
corrosive substances are usually made of glass fiber reinforced plastic.
Typically, the design uses the mean quasi-static strength of an
unreinforced E-fiber of RG = 1800 MPa.
Rigidity
The modulus of elasticity of glass fibers differs only slightly from that
of a compact volume of glass material. Unlike aramid fibers or carbon
fibers, the glass fiber has an amorphous structure. As with compact window
glass, the molecular orientation is random. The glass fiber has isotropic
mechanical properties. Glass fibers behave ideally linear elastic until
breakage. They have only a very low material damping.
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The stiffness of a real component made of glass fiber reinforced plastic
results from the modulus of elasticity, direction and volume fraction of
the glass fibers as well as to a small extent from the properties of the
matrix material, since usually, a much softer plastic is used. The modulus
of elasticity of the pure glass fiber with 70,000 to 90,000 MPa is
approximate of the order of a magnitude of aluminum.