The influence of interlayer properties on the response of laminated glass to low-velocity hard-object impact

In this combined experimental-numerical study, we intend to clarify how the interlayer properties of laminated glass plates affect their response to the low-velocity impact of a hard object. To this end, we tested twelve large laminated glass plates with polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA) interlayers combined with two annealed or heat-strengthened soda-lime-silica glass layers-three testing samples for each combination. In laboratory impact tests, both the laminated glass plate and the impactor were suspended on thin steel wire ropes to minimise the effects of boundary conditions; the velocities of the impactor and the resultant contact force were increased in repeated tests until the glass fractured. Because of the large scatter of fracture strengths, we derived the contact force for all non-destructive and destructive tests using the motion of the impactor and analysed how the contact force evolved. The laboratory impact tests also provided a dataset for validation of numerical simulations that reliably predicted the velocities at measured points and contact forces for both kinds of polymer interlayer foils, thereby validating the viscoelastic parameters of polymers determined in our previous experimental study. Using the validated numerical model, we analysed how the type of interlayer polymer material influences the impact response of laminated glass in terms of contact force and stresses and in relation to surrounding temperature conditions and impactor mass and velocity. Finally, we approximated time/temperaturedependent foil as being an elastic material with different values of constant shear moduli. For laminated glass plates containing PVB, such approximation remained valid only at low temperatures and responses could be estimated using the temperature-independent initial shear modulus. For simulations with EVA-based laminated glass plates, the elastic model with the shear modulus for prescribed temperatures and load durations provided an accurate approximation of the viscoelastic response.

Automated summary

This study investigates how the interlayer properties of laminated glass plates affect their response to low-velocity impact, using a combination of experiments and numerical simulations. The results validate the numerical model's accuracy in predicting impact velocities and contact forces, as well as the viscoelastic parameters of polymer interlayers. Additionally, the study explores how different interlayer polymer materials influence the impact response of laminated glass in varying conditions.