This study is one of the first attempts on the nonlinear forced vibration behaviors of nonhomogeneous orthotropic (NHO) structural members with linear viscous damping at primary resonance within the shear deformation theory (SDT). First, mechanical properties of double curved systems consisting of NHO materials are mathematically modeled and nonlinear basic relations are established. Using these relations, nonlinear basic partial differential equations are derived and reduced to ordinary differential equations with second and third order nonlinearities by Galerkin procedure. Multiple-scales method is used to obtain the nonlinear forced vibration frequency-amplitude dependence of double curved NHO structural members with damping. After testing the correctness of the proposed methodology, the influences of non-homogeneity, damping, transverse shear deformations and anisotropy on nonlinear forced vibration frequencies for various structural members at the primary resonance are investigated and interpreted in detail.