Accession Number : ADA309642

Title :   Static and Free-Vibrational Response of Semi-Circular Graphite-Epoxy Frames with Thin-Walled Open Sections.

Descriptive Note : Contract rept.,

Corporate Author : VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIEN CE AND MECHANICS

Personal Author(s) : Collins, J. S. ; Johnson, Eric R.

PDF Url : ADA309642

Report Date : MAR 1990

Pagination or Media Count : 217

Abstract : Experiments were conducted to measure the three-dimensional static and free vibrational response of two graphite-epoxy, thin-walled, open section frames. The frames are semi-circular with a radius of three feet, and one specimen has an I cross section and the other has a channel cross section. The flexibility influence coefficients were measured in static tests for loads applied at midspan with the ends of the specimens clamped. Natural frequencies and modes were determined from vibrational tests for free and clamped end conditions. The experimental data is used to evaluate a new finite element which was developed specifically for the analysis of curved, thin-walled structures. The formulation of the element is based on a Vlasov-type, thin-walled, curved beam theory. The predictions from the finite element program generally correlated well with the experimental data for the symmetric I-specimen. Discrepancies in some of the data were found to be due to flexibility in the clamped' end conditions. With respect to the data for the channel specimen, the correlation was less satisfactory. The finite element analysis predicted the out-of-plane response of the channel specimen reasonably well, but large discrepancies occurred between the predicted in-plane response and the experimental data. The analysis predicted a much more compliant in-plane response then was observed in the experiments.

Descriptors :   *VIBRATION, *STRUCTURAL RESPONSE, *GRAPHITE EPOXY COMPOSITES, *CRASHWORTHINESS, STRESS STRAIN RELATIONS, LOAD DISTRIBUTION, FINITE ELEMENT ANALYSIS, STATIC LOADS, STRUCTURAL ANALYSIS, STRUCTURAL MECHANICS, BEAMS(STRUCTURAL), DEFORMATION, SHEAR MODULUS, DISPLACEMENT, FIBER REINFORCED COMPOSITES, IMPACT STRENGTH, THREE DIMENSIONAL, CORRELATION, NONLINEAR SYSTEMS, SHEAR STRESSES, KINETIC ENERGY, FUSELAGES, DROP TESTS, FREQUENCY RESPONSE, TORSION, STATIC TESTS, DYNAMIC TESTS, POISSON RATIO, RADIAL STRESS, THIN WALLS, AIRCRAFT DESIGN.

Subject Categories : Laminates and Composite Materials
      Mechanics
      Commercial and General Aviation

Distribution Statement : APPROVED FOR PUBLIC RELEASE