SYMPOSIA PAPER Published: 01 January 1993

Determination of Ply-Drop Configurations


Unidirectional glass/epoxy tapered specimens were manufactured and tested under static tension and tension-tension fatigue. Four different ply-drop configurations are studied with either grouped or dispersed plies and either staircased or overlapped dropped plies. At damage events in the static tests and at prescribed numbers of cycles in the fatigue tests, the specimens were placed in a cantilever fixture to determine their bending stiffnesses. The static tests indicated that the staircased-grouped and dispersed-overlapped specimens exhibited preferred structural performance by retaining their bending stiffness up to failure. The dispersed-overlapped specimen exhibited stable delamination growth. In addition, the fatigue tests indicated slow growth in the dispersed-overlapped with corresponding losses in the bending stiffness.

Author Information

Fish, JC
Lockheed Advanced Development Company, Sunland, CA
Vizzini, AJ
University of Maryland, College Park, MD
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Developed by Committee: D30
Pages: 323–332
DOI: 10.1520/STP12637S
ISBN-EB: 978-0-8031-5252-6
ISBN-13: 978-0-8031-1879-9