Abstract:

ESDU 89011 introduces a computer program, provided as ESDUpac A8911, which calculates the lower natural frequencies of rectangular thin plates (thickness/shorter dimension ratio less than 0.05), either flat or with shallow curvature (shorter dimension/radius ratio very much less than unity). The input is structured to treat fibre-reinforced laminated plates particularly conveniently, but will also deal with isotropic materials. The effects of a uniformly distributed in-plane biaxial loading can be included but, if compressive, should not exceed 30 per cent of the buckling load. In-plane shear is neglected, as are shear deformation and rotary inertia,and the method relies on small deflection, linear plate theory. The program is restricted to plates in which the shear coupling terms in the stiffness matrix are zero. The program has been used to illustrate graphically for a typical laminated plate the effects of varying curvature and of varying the in-plane loading. The input format is explained in detail,and a worked example illustrates it and the format of the output.