Mechanical performance of transparent laminated materials for aircraft

Abstract

To fully understand mechanical and structural performance of laminated glass, seven laminated cases were designed to assess the influence of glass types, polymer interlayer thickness, polymer interlayer types and multi-layered interlayer. An innovative apparatus combining 3D-Digital-Image-Correlation and ring on ring tests have been tested successfully, major strain and out of plane displacement at the supporting side were monitored. Novel sabot design helped the rubber projectile to eject without deformation in gas gun tests. The third innovative design was the gas gun system which allowed a stereo system of two high speed cameras for 3D-Digital-Image-Correlation and one camera monitoring impact performance, strain gauge system, and detecting velocity to be synchronised at the same time. Regarding major research findings, for monolithic glasses, an approximate 0.8% major failure strain was identified regardless of its thickness which was used as a failure criterion for laminated glass. For laminated glasses, an increase of thermoplastic-polyurethane thickness will allow laminate to absorb more energy at quasi static and low velocity ranges, but lower the supporting face strain at high velocity. Chemically strengthened glass used as frontal glass layer has better performance in terms of energy consumption in quasi static and low velocity ranges comparing to thermally strengthened glass. Different types of interlayer have different functionalities. Sentry-glass-plus is more rigid comparing thermoplastic-polyurethane and polyvinyl-butyral which can transfer more shear between layers and lower the strain at the back. However, it has poor adhesion on glass proven by large peeling off of the glass fragments after gas gun experiments. Comparing with polyvinyl-butyral, thermoplastic-polyurethane has good adhesive properties with Sentry-glass-plus and glass. A multi-layered interlayer system using structural Sentry-glass-plus and adhesive thermoplastic-polyurethane as interlayers can significantly reduce the strain during impact and prevent glass fragments from flying off at high velocity which is favourable in real scenarios (e.g. bird-strike).