On the buckling load estimation of grid-stiffened composite conical shells using vibration correlation technique

In this paper, the vibration correlation technique (VCT) has been used as a nondestructive method for predicting the buckling load of grid-stiffened composite conical shells. This technique is capable of predicting the buckling load of structures without reaching failure point through modal testing. The grid-stiffened composite conical shell has been fabricated using the filament winding process. To perform the experiment, the fundamental natural frequency of the specimen is measured under stepped axial compression loading. The procedure is followed up without actually reaching the instability point when the structure collapses and is no longer usable. A finite element model has been built using ABAQUS software considering the effect of geometric imperfection in order to determine the correlation between natural frequency and applied compressive load. A comparison of the experimental and numerical approaches indicated that the difference between numerical buckling loads and those obtained via the VCT is negligible. Moreover, the VCT has provided a reliable estimate of the buckling load, especially when the maximum applied load is greater than 67% of the experimental buckling load.