Experimental and numerical approach for predicting global buckling load of pressurized unstiffened cylindrical shells using vibration correlation technique

A non-destructive method for prediction of the buckling load of a pressurized unstiffened cylinder was studied. Using vibration correlation technique(VCT), it is possible to predict the buckling load of an imperfection-sensitive cylindrical shell using correlation of loaded natural frequency with axial compressive load. An aluminum can was used as a metallic cylinder and carbon/epoxy unidirectional prepreg was used to fabricate a composite cylinder. Buckling and vibration test were performed and the loaded natural frequency of an unstiffened cylinder under internal pressure and compressive load was measured. Buckling stability was compared with internal pressure and quantitatively calculated geometric imperfection and buckling load was predicted non-destructively using VCT. The loaded natural frequency was calculated using a finite element model with measured geometric imperfection and calculated result was used for verification of the numerical VCT. The effect of internal pressure, buckling stability and geometric imperfection on the accuracy of VCT estimation was examined experimentally and numerically. It was possible to predict the buckling load within allowed tolerance of the actual buckling load.