Material selection and design strategy

A possible approach to this problem is as follows. The customer/designer must decide on the performance required from the arterfact/structure in terms of short/long-term mechanical, thermal and electrical properties, mass and environmental resistance. From this information he/she can select possible fibre and matrix types, using the information in this book, decide on the lay-up or directional nature of the reinforcement and select a suitable fabrication route. Logically, for a given set of properties, the materials which fulfil the conditions and are the least expensive and easiest to process will be chosen. 

It is difficult to be more precise without specific examples though the effects of some limiting conditions are evident if the structure must be electrically insulating carbon fibres are not suitable (see Chapter 7 for the electrical properties of carbon fibres) if fabrication must be carried out at room temperature a thermoplastic matrix could not be used while if maximum stiffness or minimum weight is vital, carbon or aramid fibres, respectively, would be employed. 

The subject of cost has been deliberately avoided so far since it depends not only on the general type of reinforcement and matrix but on the specific grade and quantity purchased. Furthermore prices are subject to revision, up or down, depending on market forces. Another factor is fabrication, which is so important for composites - it may be better to have a more expensive starting material but a cheaper or more reliable fabrication route. 

Further details on composite design are given by Mayer (1993). 

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