40207_41 - L AND TRANSPORTATION APPLICATIONS Douglas L ....

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LAND TRANSPORTATION APPLICATIONS 41 Douglas L. Denton 41.1 INTRODUCTION The use of polymer composite materials in land transportation is steadily increasing because of the cost and performance advan- tages that composites offer over competing materials. Today, composites are extensively used in well-established passenger car, van and truck applications. New applications demanding higher structural performance lev- els are under development. Railroad cars, mass transit vehicles and a wide range of mil- itary ground transportation systems offer expanding opportunities for composite mate- rials. Driving forces for the use of polymer com- posites in ground transportation applications include low manufacturing investment cost, cost reduction through parts consolidation, weight savings, good mechanical properties, 'Class A' surface quality, excellent durability characteristics, inherent dent and corrosion resistance, good noise and vibration dampen- ing, styling flexibility and dimensional stability. Factors which tend to mitigate against their use are high materials costs, low modulus and the reluctance to use materials perceived to be 'new and unproven'. Only those materials and processes which provide required performance at the lowest cost achieve long-term commercial success in transportation applications. For high-volume automobile and truck applications, high-speed Handbook of Composites, Edited by S.T. Peters. Published in 1998 by Chapman & Hall, London. ISBN 0 412 54020 7 processes must be used to manufacture parts rapidly enough to meet the production rates of the assembly plants. As a result, injection and compression molding processes are used extensively for these applications. Composites typically used in transportation applications consist of low-cost grades of thermoplastic or thermoset polymers reinforced with E-glass fibers. Often these composites also contain mineral particulate fillers. Composites con- taining high-modulus fibers, such as carbon, and higher-performance resins such as epox- ies, are used only where the higher cost can be justified to meet special product requirements. Metal matrix composites are used very spar- ingly in ground transportation. Over the past 50 years, the use of polymer composites generally has progressed from low-performance applications towards more demanding applications requiring excellent surface appearance, high mechanical proper- ties, increased temperature stability or improved durability. With increasing demands to reduce vehicle weight for improved fuel economy, and to reduce invest- ment costs for greater competitiveness, the use of composites in ground transportation is expected to increase for many decades to come. 41.2 ECONOMICS AND MARKET GROWTH The steady growth in the use of composites for land transportation is attributed primarily to the development and acceptance of new appli- cations. From the late-1960s to the mid-1990s
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906 Land transportation applications composite usage in USA transportation more than quadrupled (Fig. 41.1), and since the
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40207_41 - L AND TRANSPORTATION APPLICATIONS Douglas L ....

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