Transverse Bending and Axial Compressing Mechanical Characteristics of Carbon Fiber Reinforced Plastic Sandwich Laminated Square Tubes

Abstract

The transverse bending and axial compressing mechanical properties of carbon fiber reinforced plastic (CFRP) sandwich laminated square tubes with two kinds of cores, aluminum honeycomb and aluminum foam, respectively, were studied. The failure mechanism and damage processes of the two different CFRP sandwich laminated square tubes were studied by three-point bending and axial compressing experiments, comparing to CFRP hollow laminated square tube. The three-point bending process of CFRP sandwich laminated square tubes were also simulated in ABAQUS/Explicit and the failure mechanism and modes were deeply analyzed. The analytical model of composite laminated box beam using shear-deformable beam theory was extended to calculate the stiffness characteristics of CFRP sandwich laminated square tubes. The variation of bending, axial and shear stiffness in the linear elastic range were predicted. The results show that, after reaching the peak of three-point bending load, the bearing capacity of CFRP hollow laminated square tube reduced greatly due to the buckling instability of the two vertical sides, while that of the CFRP sandwich laminated square tubes were still considerable. A sudden strength damage occurred in the CFRP sandwich laminated tubes under the axial load, and the sandwich panels could slow down the drop of bearing capacity and increase the energy absorption. The load–displacement histories of numerical simulation and experimental result were in good agreement. The differences between analytically calculated and experimental measured stiffness characteristics were within 6.5%. The bending stiffness and axial stiffness of CFRP sandwich laminated tubes are large when the ply angle in the range from 0 to 45 degrees. Compared with the CFRP aluminum foam sandwich square tube, the specific stiffness and specific energy absorption of CFRP aluminum honeycomb sandwich square tube were higher but the energy absorbed was inferior.