Structural Optimization And Simulation Of Ultra-thin Protective Glass For Auto

Protective glass is a transparent material which can withstand various shock, constant load and has high transmittance and good mechanical property. It includes four categories:monolayer tempered glass, laminated glass, filmed glass and composite glass. The ultra-thin protective glass this paper researched is a kind of composite glass. This composite glass consists of inorganic glass, polyurethane (PU) and polycarbonate (PC). The existence of organic material can reduce its specific gravity. Thus, the protective capacity of composite glass is better than that of laminated glass when their thicknesses and weight are same. And the composite glass would not produce the shattering fragments if it is not penetrated. Compared with international corporates, the protective glass of automobile in our country is made up of over four layers, so the corresponding thickness is always more than 5mm. Furthermore, the technology of ultra-thin glass in China does not develop well and most research focused on the improvement of processes and modification of materials. Therefore, it is important to analyze the effect of each layer on the whole mechanical property of composite glass. And the trend in development of protective glass is to produce high impact strength, high transmittance, thin and light glass. However, the manufacture of ultra-thin glass requires very advanced procedure and the corresponding cost is large. Thus, there are few researches about the mechanical property of ultra-thin protective glass. The lack of data made it hard to build a complete design library which can instruct the structure design of protective glass and optimize related parameters of processing. To solve this problem, the Finite Element Method (FEM) is used to build the macro-model which contains the effect of material models, methods of structural combination, etc. This model can predict and improve the mechanical property of composite glass without implementing field experiments.This paper put up with the constitute model of composite glass by investigating the mechanical property of tempered glass. And related software was used to verify the constant of model. Then the composite glasses with different thicknesses and different compositions were manufactured by hot pressing process. The properties of these glasses were investigated by the self-built device which was used to test impact strength. At last, AnsysWorkbench was chosen to simulate the process of impact test. Through combination of simulated data and experimental results, the parameters of simulated settings can be optimized. Thus the design library can be completed, the impact strength of protective glass can be predicted. The specific researches are as follows:1. Constants of constitutive models. The Johnson-Holmquist model was chosen for the tempered glass. This model is a kind of cumulative damage failure models which can obtain the accurate dynamic response of tempered glass to impact. There are 17 constants in this model. The Effects of Strain rate was confirmed by quasi-static compression test and dynamic compression test with SHPB device. Hydrostatic tensile pressure was indirectly deduced by split tensile tests. Then value of HEL and related EOS was achieved through analyzing numerous references. At last, other constants were either obtained from original model or decided by iterative calculation.2. Verification of constants in JH-2 model. The verification of constants was done by simulating procedure of and modelling impact test of laminated glass in Ansys Workbench. In the SHPB test, the shape of compressive wave in bars which was calculated by my constants are compared with that of field tests. At the same time, the contrast team are introduced by simulating SHPB tests with original constants and annealed glass’s constants of JH2 model. In impact tests, the fracture morphology of galss which was obtained by simulation was compared with morphology of field tests.3. Impact test of composite glass. According to the regulations of GA844-2009, testing device was designed and used to investigate the impact strength of protective glasses. The experiments were divided into two groups to optimize the structural design: one is the three impacts on composite glass with 68J sharp projectile, the other is six impacts on composite glass with 120J steel ball. And there are two kinds of structured in each group:TG+PU+PC and G+PU+PC. The standard to judge the impact strength of glass is the core damage area, deflection of PC, penetration and the reflected height of projectile.4. Optimization of simulated parameters. Six protective glasses with different thicknesses are modelled to investigate the dynamic responses to impact. Firstly, the initial conditions should be confirmed, including geometry of model, impact times and mechanical properties of composite glass. Then the simulation was implemented with related parameters of settings. At last, the simulated data are compared with the experimental results. If they are not matched, the related should be modified. After repeatedly adjusting the parameters, the simulated data and the experimental results can be matched.