Constitutive Model And Failure Mechanism Of Inorganic Glass Considering Complex Stress States And Strain Rate Effects

Inorganic glass,as a typical non-metallic material,is widely used in building structures,rail transportation,aerospace,and national defense and military fields due to its excellent transparency and strength.In such application scenarios,the material and structure often face threats from dynamic impact loads,involving a wide range of strain rates and diverse stress states.The inherent brittleness and defect distribution of inorganic glass also make the dynamic deformation,damage,and failure processes of structural protective materials more complex.This study aims to comprehensively investigate the combined effects of strain rate and stress state on the dynamic mechanical properties and fracture failure process of inorganic glass.By conducting systematic dynamic loading and in-situ characterization research,a constitutive model covering the material strain rate effect,loading path,and damage failure process is established to provide a theoretical basis for improving the structural protection performance of inorganic glass.The main contents of this paper are as follows:(1)Basic mechanical property research of inorganic glass under complex stress states and a wide range of strain rates.Uniaxial compression and compression-shear combined loading tests were conducted at different loading rates to obtain the stress-strain relationship and material properties of inorganic glass under a series of strain rates and loading paths.Insitu and real-time characterization of the dynamic deformation and failure process of inorganic glass specimens was carried out using high-speed camera systems and digital image correlation techniques.The experimental results showed that regardless of whether it was uniaxial loading or compression-shear combined loading,the stress-strain relationship of inorganic glass specimens was linear elastic-brittle,and the crack propagation during the failure process was mainly in the longitudinal splitting mode parallel to the compression direction.The material failure strength increased with the increase of strain rate,and the strain rate sensitivity had a significant difference between quasi-static and dynamic conditions,exhibiting a bilinear relationship throughout the process.Based on the strain rate strengthening,the strength variation law of inorganic glass material under different loading paths was obtained.(2)Study on nonlinear dynamic constitutive model of inorganic glass.A constitutive model for inorganic glass materials was proposed based on experimental results,taking into account the influence of loading path and strain rate.On the one hand,the strain rate effect of inorganic glass was accurately described using bilinear functions;on the other hand,the influence of loading path was considered as a function based on the Lode parameter to correct the error of the Johnson-Holmquist model.Finally,the constitutive model was embedded into the general finite element software ABAQUS using the user-defined subroutine VUMAT.Quasi-static and dynamic test simulations under different loading paths were carried out to verify the validity of the model.The comparison results shown that the proposed constitutive model can accurately describe the mechanical properties of inorganic glass materials under large strain rate and complex stress states.(3)Study on high-speed impact failure behavior of single-layer inorganic glass plate.Focusing on the high-speed impact response of inorganic glass plate structures,a fracture energy-related tensile damage evolution model was proposed based on the stressdisplacement relationship to effectively reduce the finite element mesh dependence of inorganic glass plate structures in high-speed impact simulations.By defining stress-staterelated element deletion criteria,premature failure of compression stress zone elements at the impact point was prevented,and timely and stable failure of tension stress zone elements on the rebound surface was ensured.According to the numerical calculation results,the failure process of the glass plate was summarized as Hertzian cracks,radial cracks on the rear surface,circumferential cracks on the impact surface,and finally fracture into fragments.The impact energy absorption efficiency of a single-layer glass plate was related to the impact velocity,and the speed range with the best energy absorption effect was determined by the thickness of the glass plate.(4)Study on ballistic performance of laminated protective structures.The dynamic response of sapphire-borosilicate glass-polycarbonate laminated protective structures under high-speed impact of a 12.7 mm API bullet was studied by conducting finite element numerical simulations.The characteristics of each layer in the structure during the impact process were analyzed,and the influence of different configurations of the middle glass layer on the ballistic resistance was compared.The results shown that,in laminated structures with similar areal density configurations,increasing the thickness of the first layer of glass in the intermediate layer can significantly improve the ballistic performance of the laminated structure.In summary,based on the basic mechanical property test results of inorganic glass,this paper established a nonlinear dynamic constitutive model considering the effects of loading path and strain rate,and applied the model in high-speed impact simulations of single-layer inorganic glass panels and laminated protective structures.The study revealed the characteristics of the damage behavior of inorganic glass structures under impact loads,providing a basis for the optimization design of transparent protective structures.