Accession Number : ADA308173

Title :   Wave Surfaces Due to Impact on Anisotropic Fiber Composite Plates.

Descriptive Note : Technical note,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s) : Moon, Francis C.

PDF Url : ADA308173

Report Date : SEP 1971

Pagination or Media Count : 27

Abstract : The application of advanced fiber composite materials to the fabrication of fan or compressor blades depends on their ability to sustain limited damage under impact forces. For small objects such as pebbles or hailstones, the impact times are of the order of microseconds. Thus the energy transmission to the blade is completed before there are any or many reflections from the boundaries. The stress waves induced in anisotropic plates by transverse, short-duration impact forces are examined in this report. The anisotropy is related to the layup angles of the fibers. Using a modification of Mindlin's approximate theory of plates, it is shown that both extensional and bending waves are generated by transverse impact. The magnitudes of the wave velocities in different directions are calculated for graphite fiber-epoxy matrix plates as well as boron-aluminum and glass-epoxy systems for various layup angles. Finally the shapes of the wave fronts or wave surfaces due to point impact are also presented for the cases mentioned.

Descriptors :   *FIBER REINFORCED COMPOSITES, *FAN BLADES, *JET ENGINES, *IMPACT STRENGTH, *COMPRESSOR BLADES, STRESS STRAIN RELATIONS, COMPOSITE MATERIALS, COMPOSITE STRUCTURES, BENDING, PLATES, BIRD STRIKES, STRESS WAVES, GRAPHITE EPOXY COMPOSITES.

Subject Categories : Laminates and Composite Materials
      Jet and Gas Turbine Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE