Analysis Of The Correlation Between The Fatigue Failure Of The Tire Compound And The Material And Other Properties

The fatigue damage of rubber materials is one of the main reasons for the early damage of tires,exploring the correlation between the fatigue damage of tire compounds and materials and other properties,then reveal the causes and evolution mechanisms of tire compound fatigue damage,which is of great significance for improving the driving safety and service life of tires.This article is based on the formula of the tread rubber of the specified model truck tire,different rubber samples are prepared by changing the formula composition and mixing process,and the samples are subjected to different degrees of tensile fatigue.then conducted tensile property testing,the relationship curves of tensile strength,constant elongation stress,elongation at break,and energy density at break and fatigue times are obtained.and combined with DMA,RPA,carbon black dispersion meter,SEM et al.After that,the mechanical properties and microstructure changes of rubber under different fatigue levels are analyzed,and then the correlation between the fatigue failure of tire compound and raw rubber system,the amount of carbon black,the combined use of carbon black/silica,carbon black segregation and tensile properties were studied.The research results are as follows:Raw rubber and carbon black are the two most used components,which have an important impact on the fatigue failure of tire rubber.This article first changed the amount of carbon black in the rubber compound and degree of vulcanization of the rubber compound,then investigated the correlation between fatigue failure of rubber compound and matrix rubber and carbon black.The results showed that the enriched carbon black-rubber agglomerated particles produced by uneven carbon black dispersion are the main cause of fatigue micro-breaking points of vulcanized rubber,the larger the filling amount of carbon black,the worse the uniformity of dispersion,the more micro-breaking points produced in the initial fatigue stage,and the lower the fatigue life.the t₁₀₀ vulcanization has little improvement in the fatigue resistance of the rubber;the 300%tensile stress-fatigue times relationship curve of the vulcanized rubber with different carbon black dosage and vulcanization degree has a similar change law,which is more than the development process of the rubber fatigue failure.After the amount of carbon black is determined,its dispersibility has an important influence on the fatigue failure of tire compound.In this paper,the dispersibility of the carbon black in the compound is changed by changing rotor speed of the internal mixer and times of thin passes of the open mill.then the correlation between the fatigue failure of rubber compound and dispersing effect of carbon black was investigated.The results showed that low rotor speed and high number of thin passes are beneficial to improve the dispersibility of carbon black,and its vulcanizate has the best fatigue resistance;the micro-fracture points are basically formed at the initial stage of fatigue,the more the number and size of the enriched carbon black-rubber agglomerated particles,the greater the number of micro-fracture points.The fatigue failure rate is not only related to the degree of micro-destruction,but also strongly depends on the elongation stress and strength of the rubber itself,the lower the elongation stress and the higher the strength,the better the fatigue failure resistance of rubber.The combined use of suitable raw rubber can improve the fatigue resistance of rubber materials.In this paper,different amounts of BR are used in the formulation of NR as a single raw rubber component to investigate the correlation between the fatigue failure of the rubber compound and the combined use of raw rubber.The results showed that,compared with the compound without BR,the addition of BR has a certain effect on the mechanical properties of the compound,which can improve the resilience and wear resistance of the compound,but has little effect on other mechanical properties;and the combined use of BR reduced the dispersing effect of carbon black,which is detrimental to rubber processing performance.In addition,the anti-crack growth ability of BR compound is enhanced,and with increase of the amount of BR,its fatigue life is significantly improved.In the raw rubber combined system,carbon black segregates in different rubbers.In this paper,three mixing and feeding sequences are designed to control the dispersion of carbon black in different rubbers,and the correlation between the fatigue failure of the rubber compound and carbon black segregation is investigated.The results showed that changing the order of adding rubber matrix and carbon black has a certain effect on the mechanical properties of rubber;the segregation effect of carbon black has effect on the fatigue life of the rubber compound,the conventional mixing process has the best carbon black dispersion uniformity,and the rubber compound has the best fatigue resistance performance;the SEM test results showed that the NR/CB+BR process is beneficial to reduce the generation of micro-destructive points.In addition,considering the green development concept of tires and the respective advantages of carbon black and silica for rubber performance,this article adds different amounts of silica to a single carbon black reinforcement system,and then correlation between the fatigue failure of rubber compound and combined use of carbon black/silica was investigated.The results showed that:the combined used of silica has little effect on the mechanical properties of vulcanizate;Increasing the amount of silica is beneficial to reduce the rolling resistance and heat generation of tire compound,and an appropriate amount of the combined use of white carbon black can improve the dispersion effect of filler,and the microscopic failure point of the initial fatigue of the compound is less,thereby increasing the fatigue life of rubber compound.Comprehensive analysis found that the fatigue failure of tire rubber compound has a good correlation with the constant elongation stress of the material,the relationship curve between constant elongation stress and fatigue times can reveal the microscopic development process of fatigue failure of rubber materials.