| As a flexible composite material,the cord/rubber composite material has high strength and elasticity,widely used in many rubber composite products such as tires and rubber base.The lap joints of the cord layer is a common connection form in rubber composite products,which directly affects the safety.Then,this paper takes the lap joints of the cord/rubber composite layer as the research object to carry out a systematic study of its mechanical behavior and failure mechanism.this paper will adopt the method of experiment and numerical simulation to study mechanical properties and evolution process of the cord/rubber composite material lap joints,and obtain lap length,rubber thickness between cord layers and temperature which will have influence of lap joints mechanics performance,and reveal the failure mechanism of the cord/rubber composites lap joints,and provide theoretical guidance for the design of cord/rubber composites.Firstly,the mechanical properties of the base material of cord/rubber composite materials(nitrile rubber and nylon cord)were studied to obtain the influence of temperature on the mechanical properties of the rubber material,and the Yeoh superelastic constitutive model is used to characterize the stress-strain relationship of rubber materials at different temperatures.The Marlow model is used to characterize the stress-strain relationship of the nylon cord,which lays the foundation for the finite element simulation analysis.Secondly,an experimental study was carried out on the mechanical behavior of the cord/rubber composite materials lap joints,considering the influence of the lap length,the rubber thickness between the cord layers,and the temperature on the mechanical properties of the test specimen,and obtain the influence of each influencing factor on the stiffness,ultimate load and minimum breaking elongation of the lap joints,and discuss the failure morphology of the cord/rubber composite lap structure,to determine the influence of each influencing factor on the failure mode of the lap joints.Thirdly,the lap simulation model with solid cords and the lap simulation model with rebar were established,and the stress distribution state of the cord/rubber composite lap joints under tensile load was obtained.The simulation and test data are compared to verify the accuracy of the simulation model.Based on the rebar model,the influence of the material on the mechanical behavior of the lap joints was analyzed,and the influence of the material mechanical properties on the stiffness characteristics of the lap joints and the maximum shear stress between the layers was revealed.Finally,by using the cohesive model,a damage simulation model of the cord/rubber composites lap joints was established,and the failure characteristics of the lap joints were simulated.The tensile shear strength and peel strength of the cord/rubber composite delamination were tested and obtained through the tensile shear test and the T peel strength test.The parameters such as fracture toughness and other parameters were obtained use simulation parameter inversion method;Based on this model,the influence of fracture toughness on the simulation results was studied,and the strength of different lap lengths was predicted.The simulation results are in good agreement with the experimental results.The research results of this paper can provide theoretical basis for the design of the cord/rubber composites lap joints,and have high theoretical value and application value. |
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