Accession Number : ADA302022

Title :   Measurement of Displacement Around Holes in Composite Plates Subjected to Quasi-Static Compression.

Descriptive Note : Contract rept.,

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

Personal Author(s) : Duke, John C., Jr. ; Post, Daniel ; Czarnek, Robert ; Asundi, Anand

PDF Url : ADA302022

Report Date : JUN 1986

Pagination or Media Count : 65

Abstract : Contour maps of thickness changes were obtained for three quasi-isotropIc graphite-epoxy plates with central holes, loaded in compression. Thickness changes were determined for six load increments from nearly zero to within a few percent of the failure load. The largest change of thickness occurred near the hole but not at the boundary of the hole. Below 90% of the failure load, the thickness changes were nearly proportional to load. irregularities of thickness changes occurred in zones of compressive stresses and they were attributed to localized fiber buckling. A new optical technique was developed to measure thickness changes with high sensitivity. it utilizes a omparatively simple means of holographic interferometry on both sides of the specimen, followed by additive moire to obtain thickness changes as the sum of the out-of-plane displacements. Sensitivity was 0.0000125 in. per fringe order. The fringe patterns represent thickness changes uniquely, even when specimen warpage and consequent out-of-plane disp%a tents are very large. (MM)

Descriptors :   *COMPOSITE MATERIALS, *DISPLACEMENT, *HOLES(OPENINGS), THICKNESS, LOAD DISTRIBUTION, FIBERS, NONDESTRUCTIVE TESTING, OPTICAL DETECTION, LOADS(FORCES), COMPOSITE STRUCTURES, INTERFEROMETRY, HOLOGRAPHY, PLATES, BUCKLING, STRAIN GAGES, FAILURE(MECHANICS), AXIAL LOADS, OPTICAL FILTERS, HOLOGRAMS.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE