Fractional viscoelastic characterization of laminated glass beams under time-varying loading

Laminated glass is a composite made of elastic glass layers sandwiching thin viscoelastic polymeric interlayers. There are several types of polymers, traditionally modelled as linear viscoelastic materials using a Prony's series of units in the Maxwell-Wiechert arrangement. We show that one single element with fractional viscoelastic properties (two constitutive parameters that depend on environmental temperature), is sufficient to provide an accurate description of the polymer response under arbitrary time-varying actions. This is a great advantage over the classical viscoelastic characterization, which requires at least 10–15 terms in the Prony's series, each one characterized by a relaxation time, so that the series covers the time-scale of the applied actions. Fractional viscoelasticity is incorporated in the analytical model of a three-layer laminated beam, susceptible of a zig-zag warping of the cross section, which is analyzed under time-dependent loading. The great potential of this approach is demonstrated in representative case studies.