Buckling prediction of composite lattice sandwich cylinders (CLSC) through the vibration correlation technique (VCT): Numerical assessment with experimental and analytical verification

Abstract

One of the best nondestructive techniques to evaluate the buckling behavior of imperfection-sensitive structures is the vibration correlation technique (VCT). This paper presents an analytical formulation for the free vibration of axially loaded composite lattice sandwich cylinders (CLSC) and numerical and experimental validations of the VCT applied to such structures. From an analytical point of view, the equations are obtained through the Rayleigh-Ritz method considering first-order shear deformation theory (FSDT). For the numerical verification of the VCT, three types of linear and nonlinear finite element analyses are performed. At first, numerical results for the critical buckling load and the first natural frequency at different load levels are compared with the corresponding analytical ones, validating the numerical models. Then, the numerical models are extended considering geometric nonlinearities and imperfection to simulate the variation of the first natural frequency of vibration with the applied load. As well, a nonlinear buckling analysis is also performed using the Riks method for a better comparison of the VCT results. In the last section, four specimens are fabricated using a new rubber mold and a filament winding machine. Additionally, the experimental buckling test is carried out, verifying the results of the VCT approach. The results demonstrate that the maximum difference between the estimated buckling load using the VCT approach and the corresponding nonlinear and experimental buckling loads is less than 5%, being the VCT result more accurate than the numerical one. Moreover, the proposed VCT provided a good estimation of the buckling load of the CLSC, considering a maximum load level of at least 62.1% of the experimental buckling load.