| In recent years,no matter in the ocean or inland rivers sailing ships,impact collision accidents have occurred,resulting in many disastrous consequences.Therefore,it is of great significance to study the ship protective structure.Among many protective structures,thin-walled metal structures are often used in collision energy dissipation systems of ships,high-speed railways,automobiles and other vehicles for their advantages of light weight,low cost and easy processing.When Shear Thickening Gel(STG)is subjected to external impact,the viscosity of the system will increase sharply,and the material will thicken and harden.This process can absorb a large amount of energy.Therefore,filling shear thickening gel(STG)in the energy-absorbing structure can further optimize the energy-absorbing characteristics of the structure.In this paper,a shock-resistant energy-absorbing structure is designed which can be filled with STG.The structure is composed of a drum thin wall outer tube and a built-in curved grid plate.Firstly,the properties of STG material were studied.STG with different composition ratio and heating time was prepared.Rheometer was used to analyze the rheological properties of STG with different preparation processes.Then,the dynamic mechanical properties of STG under high strain rate were studied and analyzed by the Hopkinson pressure rod system(SHPB).At the same time,the deformation process of STG under high-speed impact was photographed by a high-speed camera and analyzed.By using Abaqus,the simulation model of drum thin-walled structure is established,and the influence of parameters such as amplitude of thin-walled outer tube,elongation of grid plate,number of grid plate and different impact velocity on the impact energy absorption characteristics of the structure is studied by simulation method.Finally,the impact energy absorption characteristics of the drum thin-wall structure filled with STG are analyzed,and the influence of different filling volume,different impact velocity and different mass fraction of STG on the impact energy absorption characteristics of the structure is mainly studied.Specific research contents and main conclusions are as follows:1.Preparation and rheological analysis of STG.With the increase of BA mass fraction,the more limited the creep performance of STG is.When nano-sio2 is added,the creep performance of STG is most restricted,which indicates that the creep of STG can be limited by adjusting the distribution ratio.The rheometer is used to study the rheological properties of STG.The experiment shows that the energy storage modulus of STG increases with the increase of angular frequency,showing excellent shear thickening and hardening properties.Based on the standard linear solid model,the constitutive model of STG is fitted and the rheological properties of STG are accurately described.2.Study on mechanical properties of STG under high-speed impact.The mechanical properties of STG under high speed impact were studied by using Hopkinson pressure bar system.With the increase of strain rate,STG completes the phase transition from viscous fluid state to glass state,and yield phenomenon occurs during this process.At the same time,STG exhibits strain rate-sensitive mechanical behavior,and the stress increases significantly with the increase of strain rate.The deformation of STG under impact load was captured by a high-speed camera.The STG changed from a static viscous flow state to a glassy fragment when it was broken.With the increase of BA mass fraction,the fewer fragments generated by STG and the shorter splash distance.It is shown that STG also has a good energy absorption capacity under high loading rate,which provides an experimental basis for the design of buffer energy absorption structures based on STG.3.Influence of drum thin-wall structure parameters on impact energy absorption characteristics.A new type of drum thin wall structure is designed,which is composed of a drum thin wall outer tube and a built-in curved grid plate.The structure simulation model is established by Abaqus and the simulation analysis is carried out.The simulation results show that the energy absorption effect of the structure decreases with the increase of the amplitude of the thin-walled outer tube,but too low amplitude will lead to the instability of the structure.With the increase of the elongation of the grid plate,the initial peak value of the structure is greatly reduced,and the initial peak force is reduced by 85.26% compared with the original structure,and the energy absorption effect is significantly enhanced.The initial peak force of the structure increases with the increase of the number of grid plates,and the energy absorption effect decreases.At higher impact velocity,although the structural energy absorption increases,the increase of energy absorption shows a downward trend,and the energy absorption effect is weakened.4.Influence of STG filling on impact energy absorption characteristics of drum thin-wall structure.The effect of STG filling on the energy absorption properties of the structure under dynamic impact is studied by simulation.The simulation results show that with the increase of the volume of STG,the energy absorption of the drum thin-wall structure increases continuously.The structural energy absorption increases with the increase of the mass fraction of BA in the STG and the addition of nano-sio2.When the impact velocity is 25m/s,the energy absorption effect of the structure is the best.Compared with the drum type thin-wall structure without STG filling,the maximum energy absorption is increased by 41.23%.Based on the above conclusions,it can be concluded that the STG/drum thin-wall composite structure can effectively reduce the initial peak force and significantly increase the energy absorption of the structure,which shows great application potential in the field of impact protection. |
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