Research On The Mechanical Properties Of Cord/rubber Composite Structure Under High Strain Rate

As a kind of flexible structural composite material,cord/rubber composite has the advantages of high strength,deformability and lightweight,and its products have been widely used in aerospace and other fields.However,with the development of aerospace technology,the high strain rate and other severe service conditions have brought challenges to the mechanical properties of the composite products.At the same time,the lap-joint structure is widely used in this kind of composite products,whose performance directly affects the life and safety of the products.Therefore,in this paper,the effect of processing parameters on the properties of cord/rubber composite laminates under high strain rate is studied by combining experimental study with numerical simulation.It provides theoretical guidance for the structural design of typical aerospace rubber composite products.Firstly,the constitutive model of tire cord/rubber composite under high strain rate was established.The mechanical properties of nylon cord,NBR and single ply cord/rubber composites were tested at different strain rates,and the high strain rate and low strain rate stress-strain curve were obtained.Marlow model was used to characterize the hyperelastic constitutive relation of tire cord.The elastic constitutive relation of rubber with strain rate was characterized by fitting the relation between Young's modulus and strain rate at linear stage.The accuracy of the constitutive model is verified by comparing the test and simulation results,which lays a foundation for the finite element simulation analysis.Secondly,the effects of different lamination structure parameters(lap length,lap distance and cord angle)on the mechanical properties of cord/rubber composites were investigated.The specimens with different laminates were designed according to different structural parameters,and the effects of various factors on the modulus,strength and elongation at break of the composite were obtained.The failure mode of the specimen is analyzed and discussed theoretically.The stress distribution of the specimen under high strain rate was analyzed by finite element simulation.A DIC test platform was also built to analyze the surface strain law of the samples with different cord angles during the tensile process.The correctness of the obtained law is shown,which lays a foundation for the subsequent proposal of improving the lamination structure of the products.Finally,based on the above-mentioned constitutive model of cord/rubber composite,the finite element simulation model of aerospace flexible support engineering products is established.The mechanical properties of the product with or without lap-joint structure were compared and analyzed,and the influence of lap-joint structure on the mechanical properties of the composite product was revealed.Based on the effect of the different lamination structure parameters on the mechanical properties of the composite,an improvement scheme of the structure of the flexible bearing products is proposed.It provides a theoretical basis for the design of the lamination structure of the cord/rubber composite products,and has a higher theoretical significance and application value.