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APPLICATION OF THE METHOD OF DYNAMIC STIFFNESS FOR CALCULATION OF THE FREQUENCY OF NATURAL OSCILLATIONS OF COMPOSITE SHELLS,
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
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The method for solving problems of determining the frequency of natural oscillations in composite shells by means of the method of dynamic stiffness is as follows by laying out several cross-sections, instead of a composite shell, difference shells of simple types cylindrical, spherical, conical, etc. are obtained. Forces loads, moments varying harmonically with an as-yet unknown frequency omega are introduced in the crosssections. The problems of the forced oscillations of each of the shells under the action of boundary loads are then solved. The end deflections found by solving these problems make up the dynamic stiffness, i.e., the ratio of load amplitudes to the amplitudes of the deflections caused by the loads. Then, with the law of equality of interaction and the conditions of compatible deformations, an equation is evolved for the frequency of the natural oscillations of composite shells.
APPROVED FOR PUBLIC RELEASE