Influence of EVA, PVB and Ionoplast Interlayers on the Structural Behaviour and Fracture Pattern of Laminated Glass

Abstract

Architectural trends increasingly challenge material producers and engineers to create sustainable, renewable and innovative laminated glass products that combine multiple functions as in, for example, glass railings with solar cells, curved laminated glass, floors with light emitting diodes that serve as multimedia screens. All new tendencies require the development of interlayers for laminated glass, which allows laminating electrical parts, solar cells or other objects between two glass plies. For this complex lamination process, the most appropriate interlayer is Ethylene Vinyl Acetate (EVA), because its properties allow for working in low temperatures without autoclave. From the other hand, EVA material has not been defined and discussed entirely in prEN16613 standard as a suitable interlayer material, for example, for structures application like Polyvinyl Butyral (PVB) interlayer. For this reason, EVA interlayer laminates must be investigated and compared with PVB or similar interlayer laminates to evaluate its mechanical behaviour. The research paper gives an idea and compares the structural behaviour and fracture pattern and evaluates laminated glass samples with PVB, Ionoplast and EVA interlayers. Under practical circumstances, glass structures need to be designed to withstand bending stresses which may occur, e.g., due to lateral loading, that means that four-point bending tests is appropriate method for the evaluation of structural behavior. Tests were also modelled in the Finite Element (FE) ABAQUS/CAE software to calculate displacements and evaluate bending stresses. According to current research, the conclusion can be drawn that for samples with EVA interlayer, stiffness is equivalent to PVB interlayer specimens’ results and EVA interlayer can be used in the same cases as PVB material. Moreover, using FE method makes it possible to simulate accurately the mechanical behaviour of laminated glass tested in 4-point bending with high result correlation with error less than 5% while the analytical calculations show error of 10-58%.