INFLUENCE OF TEST METHOD, FREQENCY AND STRESS RATIO ON CYCLIC CRACK PROPAGATION BEHAVIOR OF 7075-T7351 ALLOY FOR AIRCRAFT APPLICATIONS

摘要

The influence of test-frequency on cyclic crack propagation behaviour at different stress ratios was investigated on aluminium 7075-T7351 plate material. The results of these tests, carried out with constant load-amplitude, were compared with the results of tests using progressive loadings with constant Kmax (DOker-test). In stage II of the fatigue crack growth curve a significant influence of the test-frequency in the range of 3 Hz to 100 Hz was not found at the investigated stress ratios from 0.1 to 0.5. The results of these Kmax-constant-tests correspond well to the tests with constant amplitude loading.