Mechanical and Microstructural Characterization of Trapezoidal Corrugated-Core Al Sandwich Panels Under Quasi-Static Compression

Sandwich panels with trapezoidal (corrugated) cores combine low weight, high specific stiffness, and energy absorption capability. This study analyzes four configurations with different core heights by means of microstructural analyses (optical microscopy, SEM/EDS, XRD) and quasi-static compression tests. The tests yield stress-strain curves with an initial linear stage, a peak, a plateau, and a densification stage. Peak stresses range from 0.5 MPa for the thickest core (P1) to 6.2 MPa for the thinnest core (P4), while the energy absorbed density (EAD) increases with strain: at ε = 30% it varies from 0.031 to 0.670 J/cm³, and at ε = 50% the thin-core configuration reaches ≈1.113 J/cm³. The face sheets and the core are both manufactured from AA 3000 series (Al-Mn) aluminum alloy; widespread micro-porosity and Fe/Mn-rich phases are observed by SEM/EDS. XRD confirms aluminum with different peak intensities ascribable to the manufacturing texture. Increasing the core height promotes earlier local/global instabilities and reduces the peak stress; the thinnest core displays higher stiffness and peak loads. These findings support the use of trapezoidal corrugation where low weight and progressive strain are required.