Experimental Observations on the Nonlinear Flexural Vibrations of Thin-Walled Circular Cylinders

摘要

Nonlinear flexural vibration experiments were performed on a 0.0033 inch thick, 16 inch diameter, and 16 inch long seamless copper circular cylinder. The study was designed to investigate the possible existence of certain nonlinear forced response vibration phenomena that have been theoretically predicted in the literature but not demonstrated experimentally. Sufficient experimental data was also taken to allow quantitative comparisons with the existing theoretical studies. Many of the nonlinear vibration phenomena predicted theoretically were observed in the present experiments. These include the well known nonlinear jump or hysteresis in the amplitude frequency response curves, and the coupled mode instability. Ultraharmonic responses were also observed. For a prescribed forcing function amplitude, however, the ultraharmonic amplitudes of response at a given mode shape and frequency were small compared to the harmonic responses for that modal configuration and frequency. Finally large vibration amplitudes were observed in subharmonic modes of shell response. Although subharmonic modes of shell response were not considered in detail in any of the existing theories they represented a very significant vibration mode in the present experimental studies. The experimental data in the present study correlates quite well with one of the more current theoretical studies. Some effects of shell imperfections were noticed but no quantitative data were obtained. (Author)