本文在處理非完全平之矩形厚板受旋轉彈性支撐和承受有同一平面的負荷及各種不同的同一平面之邊界條件和垂直平面之邊界條件的非線性自然頻率分析。非完全平的量被考慮在厚板非線性理論之應力﹣應變的關係式中,而所承受的負荷則被考慮在同一平面之邊界條件上。在分析過程中,採用 Galerkin 方法,所得結果發現非線性自然頻率受長寬比,厚變比,材料性質,非完全平的量,同一平面的拉力或壓力或剪力的大小,同一平面之邊界條件和垂直平面之旋轉彈性支撐邊界條件的影響很大。所得部份結果與文獻比較十分吻合,因此本文分析結果應屬合理。 This paper deals with the nonlinear flexural vibrations of initially imperfect, in-plane loaded, orthotropic, moderately thick plate with various in-plane and out-of-plane edge conditions. Initial imperfection is considered in the stress-strain relations of orthotropic moderately thick plates. The effects of in-plane forces are also included in the boundary conditions. Displacement functions are expressed in the form of double generalized Fourier series in conjunction with the Galerkin method. Two different types of in-plane conditions are examined in present study. It is found that the fundamental natural frequency is significantly influenced by parameters such as aspect ratio, thickness ratio, material properties, initial imperfection, in-plane forces, in-plane edge conditions and out-of-plane rotational restrained conditions. Some results of present study are compared with the existing data given in open literature, and the agreement is quite satisfactory.