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 x 92 cm (72 in. x 36 in.) and 122 cm x 92 cm (48 in. x 36 in.) for aspect ratios of 2.0 an d 1.3, respectively. The sandwich panels were fabricated using the vacuum-a ssisted resin transfer molding (VARTM) technique. The two short edges of th e sandwich panels were clamped, while the two long edges were simply suppor ted. The experimental elastic buckling loads of panels with an aspect ratio of 1.3 were 400 kN (90 Mb) for balsa core panels and 267 kN (60 klb) for f oam core panels. For balsa and foam core panels with an aspect ratio 2.0, t he experimental buckling loads were 334 kN (75 klb) and 240 kN (54 klb), re spectively. Experimental buckling results for balsa core panels of both siz es differed by 5-8% from numerical and analytical results. Differences in e xperimental and predicted buckling loads for foam core panels ranged betwee n 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), respectivel y. For balsa and foam core panels with an aspect ratio of 2.0, post-bucklin g collapse occurred at 592 kN (133 Mb) and 334 kN (75 klb), respectively. A numerical post-buckling analysis qualitatively followed that of the experi mental results. (C) 2001 Elsevier Science Ltd. All rights reserved.