Study on the Microstructure and Compression of Composite Metal Foam Core Sandwich Panels

Stainless steel composite metal foam core sandwich panels (SS-CMF-CSP) were manufactured in large-scale panels and tested under quasi-static compression. Stainless steel face sheets were attached to the SS-CMF core using two methods: diffusion and adhesive bonding. Scanning electron microscope imaging revealed grain growth in both the matrix and sphere wall for the diffusion-bonded sandwich panels. The face sheets were found to not greatly affect the deformation of the SS-CMF core under compression. However, the diffusion-bonded SS-CMF-CSP yielded a stronger product primarily due to microstructural changes that occur during the diffusion bonding heat cycle within the SS-CMF core. The diffusion-bonded SS-CMF-CSP had a plateaus stress and densification stress 17 and 10 pct higher than its baseline SS-CMF, respectively. The large-scale manufacturing was improved, and additional samples were tested with a yield and plateau strength 75 to 80 pct higher than the initial SS-CMF samples. The improved diffusion-bonded SS-CMF-CSP showed similar strengthening, with a plateau stress 16 pct higher than its base SS-CMF. Finite element analysis was completed using IMPETUS Afea that advances the current modeling of SS-CMF and was found to be in good agreement with the experimental findings.