Experimental and numerical studies on shear behavior of lattice-web reinforced PET foam sandwich panels

To solve the problem that traditional lightweight core sandwich structure is prone to core brittle failure and interface debonding, innovative sandwich panels with fiber reinforced polymer (FRP) as facings and lattice-webs, and polyethylene terephthalate (PET) structural foam as the core were designed. Five composite sandwich panels with different thicknesses of cores and facings were fabricated by vacuum infusion molding process. Three-point bending test was carried out to survey the shear properties of panels, such as failure modes and load-deflection variation laws, which disclosed that the ultimate shear loads of the sandwich panels could be increased by 96.1% and 25.5% by heightening the thickness of the foam core from 40 mm to 80 mm and adding (0,90 degrees)/(+/- 45o) layers. Theoretical formulas were then put forward to calculate the ultimate loads, and the error between theoretical and test values was within 10%. Finally, the shear mechanical characteristics of the sandwich panels under the three-point bending test were simulated with the finite element software ANSYS, and the change rules of the bearing capacity and deformation of the sandwich panels under various test parameters were obtained. Parametric analysis proved that increasing the lattice-webs thickness by one factor can heighten the ultimate shear value of sandwich panels by 95.9%, and longitudinal lattice-webs spacing greatly influenced the ductility performance of panels.