A theoretical analysis for functionally gradient materials (FGMs) of I-section beams is introduced
in the present study. Analytical methods are set in the form of equations, in order to provide a
method for predicting the normal stress distribution of the FGMs beam under axial load and
bending moment; using the effective principal axes. Considering the elastic modulus to be a power
function, the effect of the non-homogeneity parameter on the distribution of the normal stress, as
well as on the position of the neutral axis along the beam height, is discussed. The results obtained
show that the non-homogeneity parameter has a great effect on the normal stress distribution and
on the position of the neutral axis