Study On Impact Resistance Of Shear Thickening Fluid And Its Application In Typical Protective Structures

Impact is a common phenomenon in human life.When a collision occurs,parameters such as force,displacement,velocity and acceleration will change significantly.Impact is like forging hammer iron,parts stamping and other aspects of the positive role,at the same time too large impact will also cause damage to mechanical equipment and human body.Therefore,pay attention to the damage caused by impact and improve the impact resistance of protective equipment.Shear thickening fluid(STF)is new material change material that changes from liquid to solid to resist impact,and then becomes liquid again after the impact disappears.The combination of STF and protective structure can improve the impact resistance and damage resistance of the whole protective system,which has a broad application prospect in the field of impact protection.However,the current understanding of the impact resistance of STF is still not comprehensive,such as the impact load and boundary condition constraints on the impact resistance of STF,shear thickening trigger mechanism,etc.In this paper,STF preparation,rheological property test,low-speed impact response and application of STF in soft and hard laminated protective structures and porous target plates are studied to provide reference for the application of STF in protective structures.The specific work completed in this paper is as follows:(1)The effects of different mass fraction and temperature of STF on the rheological properties of STF were analyzed.STF with different mass fractions and STF with different molecular weights in the same dispersive medium were prepared by mechanical agitation.The rheological properties of self-made STF were tested by rotary rheometer,and the viscosity properties of STFs under different shear rates were obtained.The influence of temperature change on the rheological property of STF was analyzed by temperature control system of rotary rheometer.The formation mechanism of shear thickening of STF was observed,recorded and analyzed by self-made visual test device and high-speed camera system.(2)Low-speed impact tests were carried out on STF with two different mass fractions with good shear thickening characteristics by means of drop hammer testing machine,and the effects of different impact load velocities and different mass fractions of STF on STF’s impact resistance were analyzed.Three kinds of container equivalent finite space constraints with different geometric shapes were designed,and the impact resistance of STF under different finite space constraints was analyzed.Combined with the low-speed drop weight test results,a series of numerical models were established by using ANSYS/LS-DYNA software to study the influence of finite space geometric parameters on the impact resistance of STF.(3)STF filled soft and hard laminating protective structure was designed and prepared,and three different structural designs were carried out for the software protective layer.Low-speed impact tests of three different soft-hard laminate structures were carried out by using drop hammer testing machine,and the effects of different soft-hard laminate structures on low-speed impact resistance were analyzed.(4)The STF-filled porous target plate structure was designed,and the bullet penetrating STF-filled porous target plate structure was numerically simulated by ANSYS/LS-DYNA software.The effect of STF on the perforated target subjected to bullet penetration was analyzed by comparing with the numerical simulation results of the perforated target without STF.