It is immediately obvious from Table 1.2 that the various unidirectional composite materials are highly orthotropic in terms of all of their mechanical and physical properties.The axial stiffness varies by an order of magnitude. Many have negative axial coefficients of thermal expansion,some much more negative than others.Yet,all of the materials have positive transverse coefficients of thermal expansion,although some are almost an order of magnitude higher than others.Many similar observations can be made by studying this table. Overall,the use of composite materials offers the designer tremendous design flexibility and potential.However,because the strengths are also highly orthotropic,being very low in transverse tension and compression, and in shear,special care must be taken to design properly with them.The next chapter summarizes the analysis procedures required. References 1.Y.M.Tarnopolskii and T.Y.Kincis,Static Test Methods for Composites,Van Nostrand Reinhold,New York,1985. 2.J.M.Hodgkinson,ed.,Mechanical Testing of Advanced Fibre Composites,CRC Press, Boca Raton,FL,2000. 3.Advanced Composites Design Guide,3rd ed.,R.M.Neff,project engineer,Air Force Flight Dynamics Laboratory,Wright-Patterson Air Force Base,Dayton,OH January 1973. 4.R.M.Jones,Mechanics of Composite Materials,2nd ed.,Taylor Francis, Philadelphia,1999. 5.F.P.Beer and E.R.Johnston,Jr.,Mechanics of Materials,2nd ed.,McGraw-Hill, New York,1992. ©2003 by CRC Press LLCIt is immediately obvious from Table 1.2 that the various unidirectional composite materials are highly orthotropic in terms of all of their mechanical and physical properties. The axial stiffness varies by an order of magnitude. Many have negative axial coefficients of thermal expansion, some much more negative than others. Yet, all of the materials have positive transverse coefficients of thermal expansion, although some are almost an order of magnitude higher than others. Many similar observations can be made by studying this table. Overall, the use of composite materials offers the designer tremendous design flexibility and potential. However, because the strengths are also highly orthotropic, being very low in transverse tension and compression, and in shear, special care must be taken to design properly with them. The next chapter summarizes the analysis procedures required. References 1. Y.M. Tarnopolskii and T.Y. Kincis, Static Test Methods for Composites, Van Nostrand Reinhold, New York, 1985. 2. J.M. Hodgkinson, ed., Mechanical Testing of Advanced Fibre Composites, CRC Press, Boca Raton, FL, 2000. 3. Advanced Composites Design Guide, 3rd ed., R.M. Neff, project engineer, Air Force Flight Dynamics Laboratory, Wright-Patterson Air Force Base, Dayton, OH January 1973. 4. R.M. Jones, Mechanics of Composite Materials, 2nd ed., Taylor & Francis, Philadelphia, 1999. 5. F.P. Beer and E.R. Johnston, Jr., Mechanics of Materials, 2nd ed., McGraw-Hill, New York, 1992. TX001_ch01_Frame Page 10 Saturday, September 21, 2002 4:47 AM © 2003 by CRC Press LLC