Experimental, numerical, and analytical results for buckling and post-buckling of orthotropic rectangular sandwich panels

Rectangular orthotropic sandwich fiber reinforced plastic (FRP) panels were tested for buckling in uniaxial compression. The panels, with either balsa or linear PVC foam cores, were tested in two sizes: 183 cm×92 cm (72 in.×36 in.) and 122 cm×92 cm (48 in.×36 in.) for aspect ratios of 2.0 and 1.3, respectively. The sandwich panels were fabricated using the vacuum-assisted resin transfer molding (VARTM) technique. The two short edges of the sandwich panels were clamped, while the two long edges were simply supported. The experimental elastic buckling loads of panels with an aspect ratio of 1.3 were 400 kN (90 klb) for balsa core panels and 267 kN (60 klb) for foam core panels. For balsa and foam core panels with an aspect ratio 2.0, the experimental buckling loads were 334 kN (75 klb) and 240 kN (54 klb), respectively. Experimental analytical results. Differences in experimental and predicted buckling loads for foam core panels ranged between 15% and 23%. Post-buckling collapse of balsa and foam core panels with an aspect ratio of 1.3 were 694 kN (156 klb) and 347 kN (78 klb), respectively. For balsa and foam core panels with an aspect ratio of 2.0, post-buckling collapse occurred at 592 kN (133 klb) and 334 kN (75 klb), respectively. A numerical post-buckling analysis qualitatively followed that of the experimental results