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Performance of finite dynamic elements for composite materials in plane stress
Abstract
Development of finite dynamic elements can result in significant reduction of computing time and cost for calculation of natural frequencies and mode shapes, which is an essential part of flutter prediction. Analysis with and without the dynamic terms is an alternative to constructing a new finite element mesh, to determine whether the mesh is sufficiently refined. Finite dynamic elements show spectacular improvement in convergence of higher modes with mesh refinement, but the improvement for lower modes is not so great. The element described in this dissertation is an extension of the conventional 3-node triangular plane stress element. The test problem used to study efficiency of the dynamic element formulations was a square cantilever plate. Calculations were done for an isotropic material and for an orthotropic material. The reduced time and cost is a result of achieving adequate accuracy with a courser mesh, smaller bandwidth and fewer total degrees-of-freedom. Costs are compared for computing the first 6 modes of a plate, with no mode having an error greater than a specified level. Cost reduction ratios of 16 have been observed for some modes. A cost reduction ratio of about 3 was achieved for the first 6 modes of three isotropic and orthotropic plates.
Subject Area
Mechanics|Materials science
Recommended Citation
Lung, Shun-Fat, "Performance of finite dynamic elements for composite materials in plane stress" (1989). ETD collection for University of Nebraska-Lincoln. AAI9022995.
https://digitalcommons.unl.edu/dissertations/AAI9022995