A simplified approach for local buckling in metal-faced profiled sandwich panels

Local buckling (wrinkling) is very common in metal-faced insulating sandwich panels (MFISPs) due to the small thickness of their face sheets. In some cases, wrinkling leads to sudden failures, while in others it leads to degradation of the overall stiffness and can decrease the failure load. A simplified finite-element modelling approach is presented to estimate the local buckling pressure of such panels. In the proposed approach, only the face sheet under compression is modelled, thus avoiding the need to perform a full three-dimensional (3D) structural analysis. The working assumption is that the relative deflection of the buckled face against the face under tension (unbuckled face) can be modelled using a two-parameter elastic foundation approach. The elastic foundation is simulated by closely spaced horizontal and vertical springs that model the rigidities of the foam core. Two models are used to determine the elastic foundation properties. The simplified approach was validated through comparisons with 3D analyses of full sandwich panels and available experimental results. It was found that the proposed approach can be applied to various types of MFISPs (flat or heavily profiled) with a variety of foam cores and face sheet thicknesses.