Research On A Kind Of Random Vibration Fatigue Life Analysis Technique

Research on fatigue experienced different development stages. Initially, the fatigue study theorybased on materials mechanics, and later to meet the growing demand for precision from theengineering practice for fatigue design, developed into the elastic-plastic mechanics, fracturemechanics as a theoretical basis. With vibration excitation in the service environment of engineeringstructures becoming increasingly prominent, there has been a fatigue branch combined with vibrationtheory. Vibration fatigue theory is the theory combined dynamic analysis with fatigue analysis tostudy the theory of the structure fatigue damage law. The actual structure of the fatigue damageprocess can be divided into different stages according to the order of damage size. At different stages,there are different fatigue analysis methods which can be used to analyze. For example, during thestage of fatigue crack growth, the methods of fracture mechanics can be used to simulate the crackpropagation process. However, a lot of fatigue life analysis methods are usually not considering thedifferent stages of fatigue damage process. These methods inevitably produce calculation errors. Forthis situation, the fatigue life calculation in this paper considers the different stages, trying to simulatecrack propagation fatigue life under random vibration excitation, and thus can correct the results offatigue life.Based on the aircraft fairing stent fatigue experiment under random excitation, this paperinvestigated the actual stent fatigue failure process. The dynamic characteristics of stent under certainexcitation condition are examined. And this paper observed the changes of the structure dynamiccharacteristics throughout the experiment. Then the finite element analysis of fatigue life is carried out.It is important to establish a reasonable finite element model. So, the finite element model is updatedby experimental data. Compared the finite element fatigue life results with the experimental values,this paper studied the error of random vibration fatigue results which came from the traditional fatiguelife analysis methods. For more accurate fatigue life, this paper proposed a new method of fatigueanalysis, and finally compared with experimental results verified the feasibility. The results show thatthe lifetime analysis method is reasonable and provide an idea for the vibration fatigue life analysis.Supported by State Key Laboratory of Mechanics and Control of Mechanical Structures.