Fatigue Damage Analysis on Aluminium Alloy Specimens Under Strain Loading Sequences Associating with the Kurtosis-based Coefficient

Constant amplitude data obtained from smooth specimens have been used for many years to evaluate the fatigue life of components. However, most of the loadings used in real applications are variable or random. This paper discussed the analysis on fatigue signal of Al 6061 specimen under three types of loading sequences, i.e. constant loading (CL), Hi-lo (HL) and Lo-hi (LH) associating with Integrated Kurtosis-based Algorithm for Z-filter (I-Kaz) technique. Fatigue test was performed according to the ASTM E466-96 standard with attachment of 2 mm strain gauge at the gauge of flat dumbbell shape specimen. Fatigue test was carried out at all the three types of loading stress at the sampling frequency of 8 Hz. Series of strain data were collected throughout the test from initial until failure occur using a data acquisition system. The respective I-kaz coefficients and the three dimensional plot s were used to analyse and interpret the strain signals. Fatigue damage for thress loading sequences were compared, and it was found that the I-kaz coefficient was linearly correlate to fatigue damage, hence, it is worth to see the capability of this method to representing the fatigue damage of metallic materials.