Accession Number:

ADA303914

Title:

Experimental Investigation of Graphite/Polyimide Sandwich Panels in Edgewise Compression.

Descriptive Note:

Technical memo.,

Corporate Author:

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER

Personal Author(s):

Report Date:

1990-10-01

Pagination or Media Count:

147.0

Abstract:

This study experimentally and analytically investigates the local and general buckling behavior of graphitepolyimide sandwich panels simply supported along all four edges and loaded in uniaxial edgewise compression. Material properties of sandwich panel constituents adhesive and facings were determined from flatwise tension and sandwich beam flexure tests. An adhesive bond study resulted in the selection of a suitable cure cycle for FM-34 polyimide film adhesive and, a bonding technique using a liquid cell-edge version of that adhesive resulted in considerable mass savings. Tensile and compressive material properties of the facings quasi-isotropic, symmetric laminates of CelionPMR-15 were determined at 116, R.T., and 589K -250, R.T., and 600 F using the sandwich beam flexure test method. Results indicate that GrPI is a usable structural material for short term use at temperatures as high as 589K 600 F. Buckling specimens were 30.5 x 33.0 cm 12 x 13 in., had quasi- isotropic symmetric facings and a glasspolyimide honeycomb core HRH-327-38-4. Core thicknesses varied 0.635, 1.27, 1.91, and 2.54 cm 0.25, 0.50, 0.75, and 1.0 in. and three panels of each thickness were tested in edgewise compression at room temperature to investigate failure modes and corresponding buckling formulas. Specimens 0.635 cm 0.25 in. thick failed by overall buckling at loads close to the analytically predicted buckling load all other panels failed by face wrinkling. Results of the wrinkling tests indicate that several buckling formulas were unconservative and therefore not suitable for design purposes recommended wrinkling equations are presented. In conclusion, the buckling behavior of GrPI sandwich panels, predicted analytically, has been characterized experimentally and results compare favorably. MM

Subject Categories:

  • Laminates and Composite Materials
  • Plastics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE