Research On Influence Of Polymer Interlayer On Mechanical Characteristics And Fracture Mechanism Of Laminated Glass

Laminated glass has a special sandwich structure,which can effectively improve its safety during the process of accidental collision.The existence of interlayer material can not only effectively improve the energy absorption capacity of laminated glass when subjected to external loads,but also avoid the splashing of glass fragments after the failure of laminated glass.In this paper,the mechanical properties of two typical interlayer materials,i.e.PVB and SGP,are investigated,then the influence of interlayer material on the mechanical characteristics and facture mechanism of laminated glass is systematically elucidated,based on the combination of theoretical analysis,experiments and numerical simulation.The uniaxial tensile tests under different strain rate and temperature are conducted to investigate the effect of strain rate and temperature on the stress-strain relationship of PVB and SGP materials under large strain.The tensile constitutive model of SGP material is established.Based on the stress relaxation experiments,the relaxation constitutive model of PVB and SGP materials is established,and the mechanical properties of the two materials under long-term load are studied.The dynamic viscoelastic constitutive model of SGP material is established by means of dynamic mechanical analysis,and the dynamic viscoelastic properties of SGP material are studied.Based on the above experiments,the mechanical properties and dynamic viscoelastic properties of PVB and SGP materials related to strain rate and temperature effect are systematically studied.Through three-point bending experiments of pure glass beam,PVB and SGP laminated glass beam,the influence of loading velocity,glass layer and interlayer thickness on fracture mode,bending stiffness and failure displacement of bending laminated glass beam is studied.Then the influence mechanism of PVB and SGP interlayer on energy absorption characteristics and mechanical response of laminated glass is systematically analyzed,which provides guidance on energy-absorbing protection of laminated glass for practical application.Through theoretical analysis,the equivalent stiffness model and equivalent thickness model of laminated glass are established.Further,the validity of theoretical models are qualitatively verified by means of comparison with the corresponding experimental results.Based on the drop-weight combined with high-speed photography experiment system,the basic law of crack propagation in laminated glass under impact loading is studied.The three-dimensional finite element model of impact system is established,and then validated based on the corresponding experimental results.The stress intensity factor(K)criterion of brittle material is proposed to describe the critical condition of dynamic crack propagation of brittle materials,and applied to the numerical simulation with crack propagation.The interaction integral method is used to calculate the dynamic stress intensity factors of crack tip,and then applied to the numerical simulation with fixed crack.Based on extended finite element method,the change law of dynamic stress intensity factors and stress wave propagation mechanism are used to clarify the crack propagation mechanism of laminated glass under low-speed impact.Finally,the effect of impact conditions,laminated glass structure parameters and material parameters on crack propagation characteristics of laminated glass under impact loading are systematically studied.