Experimental and numerical investigation of sandwich panels with polyisocyanurate foam core under shear loading

This paper presents a comprehensive study on numerical modelling and experimental analysis of polyisocyanurate (PIR) foam core sandwich panels loaded in shear. The shear beam test method follows the guidelines set by EN 14509:2013, while an alternative test setup using four-point loading is explored. Detailed constitutive modelling of PIR foam with failure based on the Rankine criterion is presented, supported by the necessary experiments for material characterization. The shear beam tests are simulated by the finite element method. The developed simulation model is validated against material and shear beam tests and subsequently employed for an in-depth analysis of the behaviour of the specimens up to failure. In particular, shear stresses and localized transverse compression stresses are examined. The combined experimental and numerical results demonstrate that the four-point loading configuration yields higher and more representative shear strength values than the standard two-point setup, primarily due to reduced local indentation and compressive failure beneath the loading plates. The finite element model reliably captures stress distributions and elucidates local effects during specimen loading. Consequently, the constitutive and finite element models presented in this study provide a solid foundation for advanced analysis of sandwich panels.