Experimental Study On The Impact Behaviour Of STF Fibre Metal Laminates And Impact Tower Development

At present,fiber metal laminate（FMLs）have been used in a certain range of engineering applications in China,and various types of fiber metal laminates have been studied extensively.Fiber metal laminates are generally formed by hot-press with metal alloys and fiber cloth as the medium,which will lead to a significant increase in the weight of the composite material while improving its impact resistance.Lightweight design is still a direction that needs in-depth research.Based on this,this paper introduces a shear-thickening Kevlar fiber/aluminum alloy laminate composite（STF-FMLs）,which can significantly change its low-velocity impact resistance without increasing or slightly increasing the weight of the composite.The work and major findings throughout this MPhil project are highlighted as follows.:（1）STF was prepared by combining SiO₂ with different particle sizes and PEG with different mass fractions,and its rheological properties were studied.The results show that:the particle size of SiO₂,the mass fraction of SiO₂ and PEG will significantly affect the rheological properties of STF,and the temperature will affect the rheological properties of STF to a certain extent.When the mass fraction of SiO₂ and PEG is 70%,the maximum shear thickening viscosity of STF is about 267 times that of 60%mass fraction,while the critical shear rate is only about 1/7 of that of 60%mass fraction.Combined with computer learning,a model and a system of rheological performance prediction method for shear thickening fluids has been developed.（2）Treat fiber cloth and FMLs with STF respectively to prepare STF fiber cloth and STF-FMLs,and test their impact resistance.Compared with samples without STF,the results show that due to the shear thickening properties of STF,the impact resistance of fiber cloth after STF treatment is increased by about 100%,and the impact resistance of FMLs after STF treatment is increased by about 1/3.（3）Two bonding materials,epoxy resin E44 and polyethersulfone film,were used to prepare STF-FMLs respectively,and the impact studies were carried out on STF-FMLs with different impact energies.The results showed that the damage modes of STF-FMLs were plastic deformation,fiber fracture,metal fracture,accompanied by interfacial delamination,fracture and delamination propagation.Moreover,the impact resistance of the composite material made of polyethersulfone is significantly superior than that of the composite material made of epoxy resin E44.（4）Deeply understand the mechanism of the drop weight test and successfully develop the drop weight impact testing machine,and perform measurement and functional calibration in accordance with the national metrology technical specifications.After calibration and test operation experiments,it is proved that this equipment fully meets the requirements of design parameters,has preferable stability and reliability,thus reached the predetermined goal.