The Effects of Ply Dropoffs on the Tensile Behavior of Graphite/Epoxy Laminates

Abstract

The effects of ply dropoffs on the stress-strain behavior, fracture modes and fracture strength of graphite/epoxy laminates in tension were investigated. Seven different layups with ply dropoffs were manufactured and tested to failure in uniaxial tension. Test variables included the number, order, angular orientation, and effective ply thickness of dropped plies. With six of the ply dropoff laminates, one side of the laminate was flat, with the outer plies of the other side of the laminate curving over the ply dropoff from the undropped, or thicker, section to the dropped section. This type of laminate is geometrically unsymmetric, and therefore bending stresses are induced in the laminate during testing. The analysis method developed was a one-dimensional model which allows the calculation of first ply failure of a ply dropoff laminate taking into account this induced bending effect. Theses.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 1988
Accession Number
ADA196485

Entities

People

  • Raymond K. Cannon

Organizations

  • Air Force Institute of Technology

Tags

Communities of Interest

  • Air Platforms
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Aerospace Industry
  • Air Force
  • Bending Stress
  • Composite Materials
  • Elastic Properties
  • Epoxy Laminates
  • Failure Mode And Effect Analysis
  • Finite Element Analysis
  • Graphitic Materials
  • Laminates
  • Manufacturing
  • Materials
  • Materials Testing
  • Mechanics
  • Orientation (Direction)
  • Stress Strain Relations
  • Stresses

Readers

  • Structural Health Monitoring of Composite Structures.