Enhanced vibration correlation technique to predict the buckling load of unstiffened composite cylindrical shells

Abstract

Recent advances applying the vibration correlation technique as a nondestructive experimental procedure for determining the in-situ buckling load of unstiffened and skin-dominated stiffened cylindrical shells are showing promising results. Previous studies associated the applicability and the convergence of the mentioned technique with the knockdown factor to be estimated. It is upon this basis that this paper proposes to exploit further this aspect towards a load factor for enhancing the buckling load estimations. The study considers existing validated finite element models for a systematic evaluation of the compliance of the vibration correlation technique and, based on such numerical results, it proposes a load factor for enhanced buckling load estimations. The concept is firstly verified for the numerical results, supporting its establishment. Subsequently, existing experimental results are reevaluated for an assessment of the devised load factor into the buckling load predictions. The appropriate magnitude of the load factors is determined through an iterative study grounded on numerical models that could be defined beforehand. Throughout the numerical- and experimental-based studies, the potential of the proposed load factor is demonstrated towards enhanced VCT buckling load estimations for unstiffened composite cylindrical shells.