“…Descriptions of the concept and the fabrication methods of FGMs can be found in textbooks by Miyamoto et al (1999) and Sobczak and Drenchev (2009). Nonlinear free vibrations of homogeneous beams have been analyzed using the approximate continuum approach (Woinowsky-Krieger, 1950;Burgreen, 1951;Srinivasan, 1965;Wagner, 1965;Evensen, 1968;Raju et al, 1976;Prathap and Varadan, 1978;Pielorz and Nadolski, 1986;Lewandowski, 1987;Singh et al, 1990b;Pillai and Rao, 1992) and by using the finite element method (FEM) (Mei, 1973a(Mei, ,b, 1986Rao et al, 1976a,b;Bhashyam and Prathap, 1980;Reddy and Singh, 1981;Sarma and Varadan, 1982, 1983, 1985Dumir and Bhaskar, 1988;Sarma et al, 1988;Singh et al, 1990a;Marur and Prathap, 2005;Gupta et al, 2009). In addition, Ray and Bert (1969) conducted an experiment to verify some analytical methods for nonlinear free vibrations of homogeneous beams, and Marur (2001) presented a review of the work published on this topic from the 1950s to the 1990s.…”