Experimental study on the interface fracture toughness of PVB (polyvinyl butyral)/glass at high strain rates

摘要

This paper presents the experimental results of high-speed tests using PVB sheets and PVB laminated glass. PVB showed a non-linear visco-elastic property in the low-speed tests. The non-linear visco-elastic property could be described using a simple spring-dashpot model including a non-linear spring. The visco-elastic parameters were determined by comparing the experimentally obtained stress-strain curves to the simulated model in which the various visco-elastic parameters are used. The strain-stress curves of PVB under high strain rates are elasto-plastic and those under the low strain rates are non-linear visco-elastic. The phenomenon can be explained from the phase transition from rubbery phase to glassy phase. Considering the results of PVB tensile tests, a simple fracture-mechanical model of PVB laminated glass was formulated to determine energy release rate G. Fracture toughness G_c of the PVB laminated glass specimens were calculated from both the experimental results and the energy release rate. Potential energy Uc was defined and also compared to the fracture toughness. Nevertheless, the critical loads increase with respect to the increase of tensile speed; potential energy and the fracture toughness remain the same order in all of the chosen tensile speeds.