Classical Plate Equation Notes

Classical Plate Equation Notes


The small transverse (out-of-plane) displacement w of a thin plate is governed by the Classical Plate Equation,


where p is the distributed load (force per unit area) acting in the same direction as z (and w), and D is the bending/flexual rigidity of the plate defined as follows,


in which E is the Young’s modulus, nu is the Poisson’s ratio of the plate material, and t is the thickness of the plate.

Furthermore, the differential operator  is called the Laplacian differential operator ,


If the bending rigidity D is constant throughout the plate, the plate equation can be simplified to,


where  is called the bi-harmonic differential operator.

This small deflection theory assumes that w is small in comparison to the thickness of the plate t, and the strains and the mid-plane slopes are much smaller than 1.

  • A plate is called thin when its thickness t is at least one order of magnitude smaller than the span or diameter of the plate.

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