Mechanical Damage Behavior And Mechanism Of Polyester-carbon Fiber/Pua Composites With Negative Pinssion’s Ratio

In modern naval warfare,warships and submarines will suffer explosion and impact damage.In order to reduce the damage range and improve the survival ability,a protective coating with excellent mechanical properties and energy absorption ability is needed.However,the fundamental work in this field is limited,considering that the previously existing studies of the mentioned material are mainly based on theoretical calculation and numerical simulation.In this study,the excellent properties of negative Poisson’s ratio fiber and polyurea are compounded to obtain the composites,and fundamental experimental research is carried out.In this study,HAYs were designed,and the effects of different parameters on the mechanical properties,deformation behavior and regional Poisson’s ratio of the HAYs were studied.The tensile and tear properties of polyester-carbon fiber/PUA composite under static and dynamic loads with different parameters and processes were studied.FTIR,SEM,and other methods tested and analyzed its mechanical properties and deformation behavior mechanism.The correlation mechanisms were obtained between the parameters and the tensile properties-tensile damage behaviors,tearing properties-tearing damage behaviors,and the dynamic mechanical properties of the composites.The results are as follows.(1)As the winding angle decreases and the diameter ratio increases,the fracture energy of the preform increases.The winding angle of 5°,the diameter ratio of 9:1,and the epoxy coating are the best combination parameters for the mechanical properties and deformation.The fracture energies were increased by 1.6 times,1.4 times and 1.1 times,respectively,and the minimum Poisson’s ratio was-11.18.The Poisson’s ratio law obtained by theoretical calculation is consistent with the experiment,and the minimum Poisson’s ratio is-13.26.(2)During tensile deformation,HAYs increase the tensile strength of the composites by 1.95～3.82 times.The best combination parameters of tensile properties are the winding angle of 5°,diameter ratio of 9:1,epoxy coating,and double-layer braided.Under this parameter,the maximum displacement of the composite when it is stretched to crack is24.93 mm,and the maximum strain it can withstand is 2.513.A minimum Poisson’s ratio value of-7.75 occurs,and the tensile breaking energy consumption is 2.65 times that of polyurea.The hydrogen bonding of the composite is excellent.After the damage,pits are left,and the matrix is bonded to the fiber after failure,so the interface adhesion is good.The curve in the plastic deformation stage is similar to a stepped structure,which expands the area of the plastic deformation region.The excellent macro-microstructure and tensile deformation mechanism enhance the tensile strength,optimize the tensile damage behavior at each deformation stage,and improve the energy absorption capacity of the composite.(3)During tearing deformation,HAYs increase the tear strength of the composites by 3.40～8.60 times.The best combination parameters of tear performance are the winding angle of 5°,diameter ratio of 9:1,epoxy coating,and double-layer braided.Under this parameter,the maximum displacement of the composite at fracture is 35 mm,and the maximum strain it can withstand is 1.15.The tearing energy consumption is 2.36 times that of polyurea,and the degree of hydrogen bonding of the composite is high.After the damage,pits are left,and the matrix is bonded to the fibers,so the interface has good adhesion.The plastic deformation stage is extensive,and the curve is similar to a stepped structure,so the plastic deformation area is large.The excellent macro-microstructure and tear deformation mechanism enhance the composites’ tear strength and optimize the tear damage behavior at each deformation stage.The multi-stage energy loss mechanism enhances its energy absorption capacity.(4)The dynamic mechanical properties of the composite are the best when the winding angle is 5°,the diameter ratio is 9:1,epoxy coating,and double-layer braided.The composite is in a high elastic state at the application temperature,and the compatibility between the components is good.After dynamic loading,there are more hydrogen bond interactions,high bonding degree,and good resistance to dynamic loading deformation.The dynamic performance under a wide range of temperature and frequency is consistent with the test results.The composite can resist environmental factors such as high temperature and high frequency and improve protection performance.This study explored the best design parameters of mechanical properties,deformation behavior,and energy consumption of polyester/carbon fiber-PUA composite.The changing trend of composites’ static and dynamic mechanical properties is accurately described.The correlation law and mechanism between the HAYs parameters and the composite’s mechanical properties and damage behavior were obtained.It provides fundamental work at the material level for enhancing the protection capabilities of warships and submarines.It is expected to provide a reference for selecting warships and submarines’ protective materials and the structural design of explosion and impact functional protective coatings.