  We propose in this paper a novel inverse tangent transverse shear deformation
formulation for functionally graded material (FGM) plates. The isogeometric
finite element analysis (IGA) of static, free vibration and buckling problems
of FGM plates is then addressed using a refined plate theory (RPT). The RPT
enables us to describe the non-linear distribution of shear stresses through
the plate thickness without any requirement of shear correction factors (SCF).
IGA utilizes basis functions, namely B-splines or non-uniform rational
B-splines (NURBS), which achieve easily the smoothness of any arbitrary order.
It hence satisfies the C1 requirement of the RPT model. The present method
approximates the displacement field of four degrees of freedom per each control
point and retains the computational efficiency while ensuring the high accuracy
in solution.
