Paper number 312

EDGE DELAMINATION OF COMPOSITE LAMINATES UNDER LOW CYCLE FATIGUE

Nobuhide Uda and Kazuo Kunoo

Department of Aeronautics and Astronautics, Kyushu University 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan

Summary

The onset and growth rate of free-edge delamination in composite laminates [+30n/-30n/90n]S n =1 2 under cyclic loading are quantitatively examined. A critical strain for the onset of the free-edge delamination is predicted using a strain energy release rate. The predicted critical strains are in very good agreement with the experimental results. A linear relation between delamination size and stiffness loss is shown experimentally and analytically. The growth of the delamination in the [+30n/-30n/90n]S laminates is characterized assuming the delaminations grow in both -30/90 interfaces. The growth rate of the delamination is evaluated with an alternative parameter, stiffness-loss rate during fatigue. The stiffness-loss rate of the delamination is expressed by a power law for the [+30n/-30n/90n]S laminates.

Keywords

fatigue, delamination, strain energy release rate, free-edge, fracture, toughness, growth rate, stiffness loss.