Buckling of laser-welded sandwich panels: Ultimate strength and experiments

Abstract

This is the last of three companion papers which examine the elastic buckling and collapse of laser-welded a sandwich panels with an adhesively bonded core and uni-directional vertical webs. By evaluation of the buckling stress in the first two papers it has been found that the buckling stress in compression parallel and normal to the webs typically reaches the proportional limit of the face plate and web material well before elastic buckling occurs. Hence, this paper presents an extension of the buckling model into the elasto-plastic regime, with the aim to determine the ultimate (local) strength of the sandwich and to allow experimental verification of the results. Using tangent modulus theory to 'plasticise' the elastic buckling model, the ultimate strength is evaluated for a sandwich configuration with high-strength steel face plates and a broad range of core moduli. The critical load predicted by the inelastic buckling model agrees well with non-linear finite element results and experimental values obtained from compression testing.

Two-scale micropolar plate model for web-core sandwich panels

“…The laser welds penetrate through the faces into the web-core and the panels may be filled with polymeric foams as well (Karttunen et al, 2017a). Better understanding of their limit state behavior is making way for the steel panels to more challenging applications like ship decks, see, e.g., the works of Kolsters and Zenkert (2010); Jelovica et al (2013); Jiang et al (2014);Frank (2015) and Kõrgesaar et al (2016Kõrgesaar et al ( , 2018. Kujala and Klanac (2005) have estimated that ship decks constructed of steel sandwich panels offer 30-50% weight savings compared to traditional stiffened steel plate configurations.…”

Ultimate strength of corroded web-core sandwich beams

“…1. The closed-cell PU foam used was Edulan C-1746.2, with a density  40 kg/m 3 and maximum elastic modulus Ex 8 MPa. Thus, the mechanical properties of the foam are low since the aim was only to prevent water from penetrating to the beam core.…”

“…Kolsters [3] and Romanoff [4] investigated the local ultimate strength of plate members of the sandwich panel under in-plane and out-of-plane loading. Kozak [5] studied the ultimate strength of steel sandwich columns under in-plane loading using experimental and numerical methods.…”

Experimental and Theoretical Study of Sandwich Panels with Steel Facesheets and GFRP Core

“…Cambridge University [10] developed a type of sandwich beam comprising a Y-frame and corrugated cores that were manufactured by assembling and brazing prefolded AISI type 304 stainless steel sheets together and conducted three-point bending experiments to study its extreme loading capacity and failure mode; infinite element software was also used to simulate the number of core materials, the thickness of the core material, and the angle of the corrugation, and to propose an effective design method. Swedish scholars Kolsters and Zenkert [11] performed a compression test on the laser-welded, steel sandwich panels and determined the lateral pressure failure mode, the lateral pressure ultimate bearing capacity, and the corresponding strain curve for this type of sandwich panel. Based on panels' buckling theory, those authors also predicted the ultimate bearing capacity under the lateral pressure state for sandwich panels, and their calculated values were shown to be in good agreement with the experimental results.…”