Characterization Of Viscoelasticity&Hyperelasticity Of Natural Rubber Filled With Carbon Black Of Different Particle Sizes And Analysis Of Its Shock Damping Performence

Carbon black-filled natural rubber products are widely used as shock absorber materials,and their elasticity mostly depends on the reinforcing effect of particle filler.Characterizing their viscoelastic properties and mechanical behavior,and further predicting their product performance can be better for the preparation of high performance materials and provide a reference for molding excellent products.Carbon black filled natural rubber with different particle size's was prepared in this paper.The processing characteristics of the rubber compound and the static and dynamic mechanical properties of the vulcanizate were characterized.In the ABAQUS software,the mechanical response of the double-shear specimen and the reducer was analyzed using a constitutive model that takes into account viscoelastic and hyperelastic properties.The specific research content and results are as follows:(1)The rubber processing rheological analyzer(RPA)was used to study the viscoelasticity of the two different particle size carbon blacks(N550/N774)filled natural rubber during the vulcanization process with the different filling ratio and content of vulcanizing agent(S)and the accelerator(CZ).The results show that,with the increase of carbon black content,the vulcanization is slightly retarded,and the elastic torque gradually increases;at the same filling ratio,the elastic torque slightly increases with the increase of the content of small-particle carbon black N550.When the accelerator and vulcanizing agent ratio is 3:1,the elastic torque rises first and then equilibrates in the vulcanization process,while at the ratio of CZ/S=1.5:1.5 and CZ/S=0.7:2.5,the elastic torque of the vulcanization process is rising when it begins and then fall,which is the effects of curing reversion.(2)The uniaxial,planar and equibiaxial tensile mechanical properties of natural rubber filled carbon black of different particle sizes different vulcanization degrees.The phenomenological models of Yeoh,Mooney-Rivlin,Van der Waals,and third-order Ogden hyperelastic models were used to fit experimental tensile data to obtain corresponding material parameters' values.The Yeoh model and Van der Waals model is better in description of the experimental stress-strain curves.The Yeoh model was used to establish the hyperelastic constitutive equation for analyses of the variation of the material parameters when changing the ratio of N550/N774.(3)Dynamic mechanical instrument(DMA)was used in strain sweep to study the dynamic mechanical properties of the vulcanized rubber material of different carbon black contents and the different ratios of N550/N774 as well as the vulcanization degrees.With the increase of carbon black content,the loss tangent and the storage modulus significantly change with the strain amplitude.The peak loss tangent and the corresponding storage modulus value increase with the content of carbon blacks.The rubber filled with single component of N550 has a higher storage modulus and loss tangent when compared with other rubbers filled with N774.The storage modulus of the rubber vulcanized by CZ/S=0.7/2.5 is greater than that by CZ/S=1.5/1.5,and the one by CZ/S=3.0/1.0 is the smallest amongthree samples.The frequency sweep in 0.1-50 Hz was conducted on DMA to exhibit the response characteristics of the vulcanized rubbers filled with the variation in carbon black content,filling particle size ratio and cross-linked structure.The results show that,with the increase of frequency,their storge modulus,loss modulus and loss tangent is increased,but its rised gradient is decreased.With the increase ratio of N774 by N550,the values of storage modulus,loss modulus and loss factor first decrease and then increase,and finally decrease.The values of storage modulus,loss modulus and loss factor of CZ/S=0.7/2.5,CZ/S=1.5/1.5 and CZ/S=3.0/1.0 vulcanizates decrease with the increase of frequency.(4)The Prony series was used to fit the RPA shear stress relaxation data for viscoelastic response,which was incorporated into the previously obtained superelastic constitutive relationship to establish the visco-superelastic constitutive relationship.The dynamic mechanical characteristics of double-shear parts of the rubbers filled with 70/0,40/30 and 0/70 N550/N774 were tested in sinusoidal vibration with different amplitudes frequencies.(5)The values of visco-superelastic constitutive parameters were introduces into ABAQUS for the finite element analysis of the shock absorber's mechanical behavior.