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General information
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Description
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Principle
Fibre reinforced polymers are composites that consist of fibres which are
dispersed in a continuous matrix phase. Due to a number of characteristic
advantages such as lightness, resistance to corrosion and resilience, fibre
reinforced polymers are predicted to have a great potential in future
transportation technologies, from cars and railways to aerospace.
Composition and basic materials
The two physical phases of fibre reinforced polymers are the fibres
themselves and the resin matrix. A wide range of materials can be used for fibre
reinforced materials. The most common fibre materials are: carbon, glass and
aramid. Carbon and aramid give better stiffness properties to the composite
material than glass fibre. Resins used for matrices include polyester, epoxy,
vinyl ester and phenolic types. Selecting the appropriate resin type determines
the service temperature capabilities, chemical resistance properties, electrical
and adhesive characteristics of the composite. Furthermore a number of additives
are applied such as fire retardants etc.
The overall strength of fibre-reinforced polymers is owed to the plastic flow
of the polymeric material under stress transferring the load to the high
strength fibre.
Fields of Application
Fibre-reinforced polymers are an attractive substitute for steel (or other
metals) in a wide range of applications in aerospace, automotive and
construction industries.
Mair 1999 gives the following cost and performance emphasis of different
applications of fibre-reinforced polymers.
Source: Mair 1999 |
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General criteria
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Status of development: in use |
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Fibre reinforced polymers are currently used in some railway applications for parts of car-bodies and interior panels, often in the form of sandwich composites. Other applications, especially structural applications (including motor parts etc) are still further down the road. An example for an almost marketable structural application is the flywheel storage technology as used in the Lirex experimental train. The rotor of the flywheel is primarily made of carbon fibre polymer material. |
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Time horizon for broad application: 5 - 10 years |
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(no details available) |
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Expected technological development: highly dynamic |
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(no details available) |
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Motivation:
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- Weight saving
- Corrosion resistance
- Taylored performance (cf. General criteria -
Benefits)
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Benefits (other than environmental): big |
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Fibre-reinforced polymers offer a number of advantages over steel (and other
metals). Mair 1999 gives the following list:
- High specific strength properties (20-40% weight savings)
- Ability to fabricate directional mechanical properties
- Outstanding corrosion resistance
- Excellent fatigue and fracture resistance
- Lower tooling cost alternatives
- Lower thermal expansion properties
- Simplification of manufacturing by parts integration
- Potential for rapid process cycles
- Ability to meet stringent dimensional stability
requirements
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Barriers: medium |
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Highly dependent on type of application in railways. |
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Success factors:
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(no details available) |
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Applicability for railway segments: high |
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Type of traction: electric - DC, electric - AC, diesel
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Type of transportation: passenger - main lines, passenger - high speed, passenger - regional lines, passenger - suburban lines, freight
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(no details available) |
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Grade of diffusion into railway markets:
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Diffusion into relevant segment of fleet: < 5% |
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Share of newly purchased stock: < 20% |
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(no details available) |
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Market potential (railways): high |
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(no details available) |
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Example:
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(no details available) |
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Environmental criteria
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Impacts on energy efficiency:
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Energy efficiency potential for single vehicle: strongly dependent on specific application |
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Energy efficiency potential throughout fleet: strongly dependent on specific application |
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The weight reductions in railway vehicles attainable through the use of fibre-reinforced plastics obviously depend on the share of the vehicle mass replaced by these materials and thus on the application context.
According to estimates of the Rocky Mountain Institute, weight reductions through the use of fibre-reinforced plastics may be up to 65% in the automotive industry (Pehnt 2001). This is obviously very optimistic and not as such transferable to railway conditions.
The energy efficiency through weight reductions could be compensated by the high energy demand in the production phase of fibre-reinforced polymers.
Estimates made by DLR (Deutsches Zentrum für Luft- und Raumfahrt) for automotive applications indicate that the life cycle net result of higher energy demand in production but higher energy efficiency during use may be close to zero. The concrete outcome depends on many factors such as product life, recycling strategy etc. (Pehnt 2001). |
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Other environmental impacts: negative |
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- Recycling properties are generally worse than for metals due to heterogeneity of material.
- Fibre reinforced materials often contain toxic or at least problematic chemicals especially those composites equipped with fire retardants.
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Economic criteria
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Vehicle - fix costs: medium |
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Material costs of fibre-reinforced polymers are still relatively high but have already dropped considerably in the past and are expected to drop further. The same is true for manufacturing costs. |
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Vehicle - running costs: significant reduction |
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(no details available) |
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Infrastructure - fix costs: none |
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(no details available) |
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Infrastructure - running costs: unchanged |
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(no details available) |
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Scale effects: high |
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(no details available) |
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Amortisation: not applicable |
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(no details available) |
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Application outside railway sector
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Status of development outside railway sector: in use |
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Fibre-reinforced polymers are already widely in use in aerospace, construction and cars. |
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Time horizon for broad application outside railway sector: now |
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(no details available) |
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Expected technological development outside railway sector: highly dynamic |
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The technological development potential of fibre-reinforced polymers is very high. In early decades (when aerospace sector was major driver for development) a clear emphasis was placed on material performance rather than cost issues. In more recent years increased efforts have been put into reducing manufacturing costs and design time of these materials. For example the Manufacturing Science and Technology Program of the US Department of Defence has defined as key goals to reduce design time by 75%, material costs by 25% and fabrication time by 50%. |
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Market potential outside railway sector: high |
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(no details available) |
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Overall rating
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Overall potential: promising |
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Time horizon: mid-term |
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Fibre reinforced polymers are one of the keys to further progress in light-weight construction in railways. Due to their very good performance in many areas, in mid term fibre reinforced composites will become a standard substitute for steel and other materials in many railway applications. Whereas non-structural components made from fibre reinforced materials play a growing role in railway vehicles, most structural applications require more R&D efforts. Railway operators can give however little impulses in this field but rather depend on the developments in mass markets (automotive etc). |