Full-scale shear characterization and numerical study of sandwich panels with polyisocyanurate foam core

Abstract

This study employed a custom-designed vacuum box, compliant with EN 14509:2013, for full-scale shear testing of sandwich panels. The system incorporates direct load measurement and adaptive air-leakage compensation, providing linearly increasing and uniformly distributed loading conditions that enhance conventional testing methods. Flat-faced and profiled-faced sandwich panels with polyisocyanurate (PIR) cores were experimentally investigated, while finite element analysis (FEA) was used to evaluate stress distribution and distinguish local and global failure modes. The shear modulus of profiled panels was determined using iterative and approximate methods, with the latter producing values 4–5% higher. Comparison of analytical and experimental results showed that the semi-empirical formulation overestimated total shear capacity by 16–43%, confirming that full-scale testing remains the most reliable method for assessing strongly profiled panels. The influence of span length on stress distribution was found to be significant regardless of failure mode. Finally, critical shear span-to-core-thickness ratio (L/Dc) benchmarks are proposed for each panel type, providing practical guidance for achieving shear-dominated failure in future testing.