A comprehensive investigation on bending stiffness of composite grid-stiffened and functional foams sandwich beam

This paper investigates the bending stiffness of composite grid-reinforced sandwich beams with functional foam cores by a combination of analysis, simulation, and experiment. First, the sandwich layer composed of stiffeners and foam cores is homogenized, and the equivalent mechanical parameters of the sandwich layer are proposed. Then, based on the first-order shear deformation theory, the three-point bending deflection of the beam is derived and verified by tests and simulations. Finally, the factors affecting the bending stiffness are investigated, such as the elastic modulus of the foam cores, the thickness of the stiffeners, the longitudinal and transverse spacing of the stiffeners, and the fiber lay-up angle of the stiffeners. The results of this paper are of great significance to the stiffness design and parameter optimization of composite grid-stiffened sandwich structures with foams for underwater vibration and noise reduction.