Study On Impact Resistance And Fragmentation Characteristics Of PVB Laminated Glass Under Medium And High Speed Impact

With the progress of science and technology,laminated glass and other safety glass are widely used in building glass curtain walls and automobile windshield structures.In recent years,terrorist attacks and extreme weather,such as hurricanes,have occurred frequently all over the world.As a protective structure for buildings and cars,laminated glass faces enormous challenges.Polyvinyl butyral(PVB)laminated glass is the main building and automobile glass materials.At present,many scholars have done experimental,simulation and theoretical research on the dynamic response and explosion resistance of sandwich glass under explosive load.At present,only a few scholars have studied the impact resistance of sandwich glass under concentrated load.In explosions,terrorist attacks and flying stones caused by car driving,the secondary damage caused by splashing debris from laminated glass is the most important factor causing casualties.At present,there is no systematic experimental study on the mechanism and characteristics of laminated glass fragments.At present,the impact resistance of laminated glass and the mechanism and characteristics of laminated glass debris under medium and high-speed impact load are insufficient.In this paper,the crack initiation,crack growth,splash velocity and energy of laminated glass under medium and high velocity impact are studied.Fracture analysis of laminated glass is carried out on mesoscopic scale.The macroscopic crack growth performance is combined with mesoscopic fracture analysis to explore the fracture mechanism of laminated glass.The details are as follows:1)The cracking initiation and crack growth of laminated glass under the impact of medium and high speed concentrated loads were studied by air gun impact test combined with highspeed camera and digital image processing technology.The influence of glass thickness and PVB thickness on crack initiation performance of laminated glass and the influence factors of crack propagation speed of laminated glass after crack initiation were analyzed.For the impact of laminated glass in engineering,the protective performance of laminated glass provides experimental basis and improvement direction.2)The velocity and energy characteristics of debris splash are studied by experiment and theory.The final mode of specimens is analyzed,and the characteristics of debris splash are systematically studied.The effects of laminated glass thickness,PVB thickness and impact velocity on debris characteristics were analyzed.Several distinct characteristics of the splash velocity and energy of debris are obtained.3)The fragments were analyzed by metallographic microscopy with mesoscopic size(10-3mm),and the fragmentation process was reflected by the mesoscopic model.Several obvious characteristics of debris were analyzed by fracture surface,and the effects of impact velocity,glass thickness and PVB thickness on different areas of debris were analyzed by parameters.The factors affecting the macro-size and morphology of debris are obtained.Combining with the crack growth velocity curve,the relationship between the crack growth performance and the fragment mesoscopic morphology is obtained.It provides a reference for preventing debris threat in engineering and understanding the accident process through debris.