Constitutive relationships of different interlayer materials for laminated glass

The paper presents the results of an experimental investigation on the viscoelastic response of laminated glass joints with different interlayers. The problem is explored with double lap joints under shear loadings at temperatures between 0 degrees C and 60 degrees C. The viscoelastic mechanical parameters of a polymeric interlayer play a fundamental role in determining the response of laminated glass and thus, their knowledge is required for a fail-safe design of structural and non-structural members to avoid unexpected catastrophic collapses. Tests were performed on specimens made of three glass plies to study a resilient film produced from plasticized PVB (commercially known as DG41). As a comparison, two commonly used interlayer materials for laminated glass were also tested: the polyvinyl butyral (PVB), and the ionoplast polymer SG. Firstly, short-term tests were performed at different temperatures, secondly long-term properties of both materials at 20 degrees C were predicted from experimental curves using the time-temperature superposition principle (TTSP), which allows for a reference curve (master curve) to be drawn. A method to improve the drawing of the master curve and provide values of the relaxation modulus and inverse creep compliance modulus of PVB and DG41 at different temperatures to be used for design purposes, is proposed.