Measurements have been made of the nonlinear steady‐state response of a 2‐in. by 12‐in. strip of 2024 T3 aluminum,116 in.thick, which was clamped on the short side and free on the long side. Vibrations were excited by the sound of a siren at the end of a duct in whose side the strip was mounted. Measurements were made in a broad range of frequencies around the fundamental resonance and at sound pressure levels up to 150 db,re0.0002 microbar. Skewed response curves typical of a hard‐spring oscillator were obtained. The data can be reasonably interpreted by means of a theory which includes the effects of in‐plane tension generated by large amplitudes of bending displacements. when allowance is made for a number of interesting experimental complications. (Supported by Wright Air Development Division.)