In order to analyze the approximate applicability of general simple supported symmetric laminated plates, according to the Ritz method and the
minimum potential energy principle, the closed form solution of the laminated plates was obtained after the algebraic manipulations and matrix transformation, which was convenient for
MATLAB programming. Values about the orthotropic laminate and the 10% rule laminate, obtained through the orthotropic laminated plate approximation (OA), the finite element method
(FEM), the orthotropic long plate laminate approximation (OLA), were compared with the value of exact solution, under different aspect ratio AR and ply angle θ.The result
shows that maximum displacement w0 of FEM is within 5% errors compared with exact solution. As the aspect ratio AR increases, the error tends to be stable and
consistent. Under the low bending stiffness D16, OLA w0 at the critical AR is 294.4% errors compared with exact solution about the orthotropic laminate,
while w0 is consistent at the large AR ratio. For the 10% rule laminates, as AR is getting greater than 3, FEM w0 and OA w0 are consistent with the
exact solution, and as AR getting less than 3, the w0 from the prior approximate methods meets the engineering requirements, however, error is large when under the large
bending twist coupling stiffness D16, D26, at AR=1 and 2 with θ=90°, the OA w0 are 10.98% and 8.67% errors compared with the exact
solution w0. The research has certain directive significance on the design of composite structure. |