SEDL / STP / STP1156-EB / STP24755S

High-Cycle Fatigue Crack Growth Properties of Aramid-Reinforced Aluminum Laminates

Stanzl-Tschegg, SE
Professor, University of Agriculture of Vienna, Institute for Meteorology and Physics, Wien,

Papakyriacou, M
Research assistant, University of Agriculture of Vienna, Institute for Meteorology and Physics, Wien,

Mayer, HR
Assistant professor, University of Vienna, Institute for Solid State Physics, Wien,

Schijve, J
Professor, Delft University of Technology, Faculty of Engineering, Delft,

Tschegg, EK
Professor, Technical University, Institute for Applied and Technical Physics, Vienna,

Pages: 16    Published: Jan 1993

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Abstract

The fatigue crack growth properties of the laminated fiber-reinforced composite material Arall (Arall® 1 and Arall® 2) have been studied at low cyclic stress amplitudes and high numbers of cycles. For the experiments, a high-frequency (21 kHz) ultrasound resonance fatigue machine has been used (R = -1).

In order to determine the threshold stress intensity (for Arall 1), tests were performed by increasing the stress amplitude stepwise. The resulting threshold stress intensity increases with increasing crack length. In addition, tests with constant cyclic stress amplitude were carried out (for Arall 1 and Arall 2). For these, the fatigue crack propagation rates decrease with increasing crack length and become zero at a defined crack length if the applied constant stress amplitude is lower than a defined “critical” stress amplitude. Fiber bridging, causing extensive crack closure, is the reason for this effect. At cyclic stresses higher than this “critical” stress, cracks continue to grow, though with reduced speed.

Damaging effects like delamination owing to failure of the resin in addition influence the fatigue crack growth behavior of Arall at high cyclic stress amplitudes.