Determination of Interlayer Mechanical Properties for Use in Laminated Glass Design

We have seen rapid expansion in the last decade of laminated glass design using modern analytical and computational methods. Essential to the proper simulation of laminated glass behavior is the development of accurate constitutive models for the polymer interlayer. Such models should reflect polymer behavior as a function of temperate and load duration so calculations may be made that reflect the design load case of interest. In this contribution we present several approaches to the determination of interlayer relaxation modulus behavior. Results from test methods based on dynamic mechanical analysis (tension, shear, parallel plate geometry) are compared and contrasted. Two key finding are reviewed: 1) proper sample conditioning and preparation, 2) minimization of sample deformation during testing. We show that self-consistent results may be obtained from different test geometries provided these two issue are carefully managed. A key element of any evaluation program is validation the results through additional testing. Here we examine the use of four point bend testing of laminated glass beams for such validation checks.