Test equipment for optical evaluation of strain field surrounding crack tips in graphite-epoxy laminates under impact loading

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:175186

Benitez, F G; Hognestad, G ^[1]

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1. Univ. of Seville (Spain)

This paper describes the tests performed for the optical evaluation of the stress field surrounding crack growth under impact loading. The specimens are graphite-epoxy laminates. A description of the equipment used (split-Hopkinson-pressure-bar rig, high-speed photograph camera, flash and laser illumination) is covered. The specially manufactured interface, trigger and timing electronics are also described. The described set-up can be used with the optical techniques of caustics and CGS to evaluate the strain field around a dynamically propagating crack. By employing a flash light rather than the laser light source, the crack propagation can be studied visually. The test-rig is used for testing polymers and laminated composites under in-plane impact loads. The exposed surface of the specimens which were used for crack speed measurements and stress field evaluations was covered by matte white paint and vapour deposited aluminium for light reflection. Results obtained for laminates with various thicknesses and loading speeds are presented.

• OSTI ID: 175186
• Report Number(s): CONF-950686--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRACK PROPAGATION
EPOXIDES
GRAPHITE
POLYMERS
REFLECTION
STRAINS