Fatigue crack growth rate in miniature specimens using resonance

The crack length measurement was calibrated using fractographic marking technique. The presented method was validated by performing crack growth rate tests in miniature 4 × 3 × 32 mm beam specimens with 150° chevron notch. 7075 aluminium alloy and 4043 high strength steel were tested at load frequency of 110 and 160 Hz respectively. The crack growth curves were measured in both load increase and load reduction mode and the resulting crack compare well with the baseline data available for standard central crack (CCT) specimens.