A cantilever beam of 2024‐T3 aluminum sheet (3.25 in.×1.00 in. × 0.063 in.) was shaken mechanically at its clamped end, the force being applied parallel to the thickness dimension. A 0.125‐in.‐diam hole near the clamp afforded points of strain concentration. Both pure tone and broadly filtered random forces were used to excite resonant response in the fundamental mode, at about 185 cps. The rms surface strain in a cross section containing the hole ε was monitored and held constant. LifeNto first visible appearance of a fatigue crack was measured; lifetimes ranged from about 1×105to 6×105cycles. The pure‐tone data agree very closely with previous measurements on a riveted cantilever excited by sound. In comparison with available fatigue data for reversed bending in a specimen with small concentration factor, these data yield a fatigue strain concentration factor of 1.6, in good agreement with theory. The measured ratio of rms pure‐tone strain to rms random strain yielding the same life‐time ranged from 1.5 to 1.6 (3.6 to 4.3 db). The ratio calculated from assumptions of (a) Rayleigh distribution of peak strains, (b) noninteracting accumulation of damage, and (c)Nε8.25= const, is 1.4 (3.1 db). (Research sponsored by Aeronautical Systems Division, Air Force Systems Command, U. S. Air Force.)