This paper deals with the non-linear flexural vibrations of an initially imperfect, orthotropic, moderately thick plate with various out-of-plane and in-plane edge conditions. The imperfection displacement is considered in the strain-displacement relations of an orthotropic moderately thick plate.
The displacement and force functions are expressed in the form of double generalized Fourier series. Three different types of in-plane conditions are examined, and it is found that the fundamental non-linear natural frequencies are significantly influenced by parameters such as aspect ratio, thickness ratio, material properties, initial imperfection, out-of-plane rotational restraint conditions and in-plane edge conditions. Some results of the present study are compared with existing data given in open literature, and the agreement is quite good.