Study On The Preparation And Properties Of Low Speed Impact Resistant Composites

Shear thickening fluid is a suspension system composed of nanometer or micron solid particles and polar dispersion medium.It has the property that the viscosity increases sharply at high shear rate and can be restored to the original state after the external force is removed.Because of its unique properties,shear thickener can be widely used in the field of material protection,such as human body protection,national defense and military industry.In order to expand the current research ideas of STF fiber composite materials and provide more possibilities for the design of impact protection materials,the multi-component shear thickening fluid system was introduced into the practical application.In this paper,the multi-phase shear thickening fluid with the third component was prepared,and the change of rheological properties of the system with the third component was explored,and then the multi-phase shear thickening fluid was added.At last,the mechanical properties of STF fabric composite were tested.The experimental results show that the addition of nano cellulose(CNF)can enhance the steady-state and dynamic rheological properties of nano silica shear thickening fluid,while graphene oxide(GO)and multi walled carbon nanotubes(MWNT)have destructive effects.UV irradiation can improve the interface bonding strength of Kevlar fiber and shear thickening fluid,and then improve the mechanical properties of the composite.The reason is that the surface structure of the fiber is slightly damaged,and the surface roughness and activity of the fiber are improved.Compared with pure Kevlar,the single yarn strength of Kevlar composite is greatly enhanced by compounding any kind of shear thickening fluid,but only adding CNF is better than two-component STF composite.The CNF system can improve the weight-added mass fraction of STF composite and the unit weightadded strength.The impact resistance of cotton cloth,aramid cloth,ballistic nylon cloth and carbon fiber cloth after CNF-STF composite has been improved in varying degrees,and the best reinforcement effect is cotton cloth and aramid cloth.UHMWPE is not suitable to be reinforced by STF because of its high surface smoothness.