40207_42 - MARINE APPLICATIONS Wayne C. Tucker and Thomas...

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MARINE APPLICATIONS 42 Wayne C. Tucker and Thomas Juska 42.1 INTRODUCTION resins, but their superior resistance to hydrol- ysis and blistering aacquemet and LaGrange, 1988) makes isophthalic polyester a better choice for applications requiring long term Use of composites in marine applications is widespread. The two major advantages of fiber reinforced dastics over metals are resistance to exposure to water. Use of vinyl esters is becoming more com- mon. Although they are more expensive than polyesters, vinyl ester laminates generally have better properties. In addition, vinyl esters have excellent resistance to matrix hydrolysis. Also available are mixtures of vinyl ester and polyester, which offer some of the benefits of vinyl ester but at intermediate cost. Epoxy laminating resins, rarely used in marine applications due to cost and the need for elevated temperature cure, are used by some boat builders in high performance one- off racing craft and some production boats. Among the advantages of epoxy are extended out-time compared to room temperature cur- ing resins and low volatile organic content. The material form is wet epoxy prepreg (sometimes referred to as a wet-preg to distin- guish it from conventional prepreg) made by the boat builder (Gougeon, 1992). Fabrication is normally by vacuum bag, room temperature cure followed by oven post-cure at about 50°C (122°F). the marine environment, particularly the elim- ination of galvanic corrosion and the ease of tailoring structures, which are fabricated by molding processes. In addition, composites have high strength-to-weight ratios. This chapter is an overview of the materials and fabrication processes used in marine appli- cations of composites. More comprehensive studies of the use of composites in marine con- struction have recently been published (Smith, 1990; Greene, 1990; Davies and Lemoine, 1992). 42.2 MATERIALS 42.2.1 RESINS Resins used in marine applications generally cure at room temperature, both for the low fabrication costs and because elevated temper- ature performance is not required. General purpose polyester is the most com- mon laminating resin. These materials, based on orthophthalic acid (phthalic anhydride), are the least expensive, but long term immer- sion without a barrier coat will probably result in blistering (Burrell, Herzog and McCabe, 1987). Polyesters based on isophthalic acid are slightly more expensive than general purpose 42.2.2 REINFORCEMENTS E-glass fabric is the primary reinforcement in marine construction, of which there are numer- ous forms. There are two basic styles: woven and knitted. Woven fabrics are further subdi- vided into woven roving and woven yarn. Handbook of Composites. Edited by S.T. Peters. Published in 1998 by Chapman & Hall, London. ISBN 0 412 54020 7
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Materials 917 Woven roving are the most common fabrics due to their low cost. They are available in a variety of weights and weave patterns, but a 800 g/m2 (24 oz/yd2) plain weave is probably the most frequently used. In small boat con- struction, the fabric is usually mat-backed, in
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This note was uploaded on 03/16/2010 for the course MECHANICAL ME765401 taught by Professor Prof.sulis during the Spring '10 term at Institut Teknologi Bandung.

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40207_42 - MARINE APPLICATIONS Wayne C. Tucker and Thomas...

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