Buckling of three-layered composite beams with viscoelastic interaction

A three-layered structure is composed by two external elastic beams that sandwich a viscoelastic core providing their shear coupling. The time-dependent bending of a simply-supported composite-beam of this type, axially-compressed and with an initial sag, are studied assuming a Maxwell-Wierchert constitutive model of viscoelasticity accounting for the memory effect. The phenomena of glassy-, rubber- and creep-buckling are examined for various values of the load. Comparisons are made with a quasi-elastic approximation that assumes a relaxed elastic shear modulus for the interlayer, parametrically dependent on time. The limits of this simplified approach are discussed.