Summary

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Test No. FV12 is a thin square plate model, which contains three rigid body modes. OptiStruct investigates the repeated eigenvalues and kinematically incomplete suppressions of the thin plate in normal modes analysis.

 

Benchmark Model

The 4-node quad elements with 8x8 mesh configuration are used to model the plate. The x-translation, y-translation displacements and z-rotational displacements are fixed for all nodes. The material properties for the thin plate are:

E = 200x109 N/m2, = 0.3 and = 8000 kg/m3

 

Modal Analysis Results

The frequency of each targeted mode is normalized with the closed form solution. The closed form solution is not available for mode 10, use target value for H.O.E. instead.

f* = closed form solution

 

File Location

<install_directory>/demos/hwsolvers/optistruct/fv12.fem

 

Reference

NAFEMS Ltd, The Standard NAFEMS BENCHMARKS TNSB Rev. 3, NAFEMS Ltd, Scottish Enterprise Technology Park, Whitworth Building, East Kilbride, Glasgow, United Kingdom, 1990.