Analysis Of Fretting Fatigue Life In Riveted Components

One of the causes of structural deterioration and failure of engineer structure and machine by aging can be attributed to the fretting fatigue damage, The cycle load that caused structural deterioration and failure usually is much less than the "security"load that was estimated by static fracture analysis. Fretting fatigue will conduce the normal fatigue life of components reduced notably or induce fatigue fracture early, which leads to serious accident. Developing fretting fatigue research has a far-reaching meaning.One of the causes of failure of land transportation equipment can be attributed to fretting fatigue that occurs in joint structures. Many failures in high speed train vehicles are founded under fretting circumstance, which is a main cause of failure. It is important of researching the fretting fatigue life of joint structures.The main works of this thesis are as follows:1. Based on the existing experiment results of one rivet and one aluminum specimen, the distributions of stress amplitude and mean stress along the inner and outer contact edges on the specimen's up-surface under fatigue loads were analyzed in details using finite element method. In the numerical model, the direct restrict method and the Stick-Slip friction model were introduced. A two-step loading process was suggested to realize the pre-tighten force.The cycle load was applied in the third step loading process. The contact states of the specimen's up-surface were analyzed, and the results were in well agreement with the observations of the existing experiments. Based on the analyzed results, the influences of the fastening forces,contact friction coefficient and remote stress on crack initiation of the specimen's up-surface were discussed.2. The analysis of fretting fatigue life was studied using fatigue analysis software. The influences of the different fastening forces, contact friction coefficient and remote stress on crack initiation and fatigue life of the specimen's up-surface were discussed, which more validated stress analytical results and experiment results.3. The distributions of stress amplitude and mean stress of the inner and outer contact edges on the specimen's up-surface and down-surface in the models of one rivet and two aluminum specimens under fatigue loads were analyzed in details. Friction model and loading process were the same as that of one rivet and one aluminum specimens.Based on the analyzed results, the influences of the different fastening forces, contact friction coefficient and remote stress on crack initiation of the two aluminum specimen were discussed, which were useful for the farther experimental researches.4. The analysis of fretting fatigue life was studied using fatigue analysis software.The influences of the different fastening forces, contact friction coefficient and remote stress on crack initiation and fatigue life of contact areas on the two aluminum specimens were discussed. the sameness and difference of the results of one rivet-one aluminum specimen model and one rivet-two aluminum specimens model were discussed.The contrast of fretting fatigue life forecast results and experiment results indicated that the models in this thesis are accurate. Some valuable conclusions were gained in the analysis of fretting fatigue life in the thesis. This thesis provides credible gist for farther studying on joint components.