Reliability Analysis Of Rotor Blade Considering The Friction Thermal Effect

Rotor blade is an important hot-end component of aero-engine,its reliability is related to flight safety directly.During the flight,the rotor blade will be affected by aerodynamic excitation,mechanical excitation or thermal field,leading to small tip clearance,and even friction between the blade and the casing,resulting in wear damage to the blade.Therefore,it is important to study the reliability of the rotor blade considering the friction thermal effect for the arrangements for proper maintenance and repair of the aero-engine when the rub impact happened.Aiming at the rotor blade wear reliability,a wear prediction model was proposed considering the random wear characteristics by combining the experimental design,finite element simulation and mathematical statistics.In order to analyze the reliability of the rotor blade comprehensively,the wear reliability model was established and compared with the fatigue reliability.It can be used to analyze the life of blade.The contents of the thesis are as follows:(1)Based on the Fourier equation of the rotating coordinate system and the characteristics of the blade’s partial grinding,the rub impact model of the blade-casing considering friction thermal and structure coupling was established,and the thermal-structural direct coupling calculation was carried out using the finite element software.Compared with the blade stress field without considering the friction thermal effect,it is found that the friction thermal effect of rub-impact has a significant effect on the stress field of the blade.Therefore,the influence of the friction heat on the blade cannot be neglected;(2)Based on the thermal-structure coupling model which was mentioned above,the blade wear model was added.Compared with the stress field and temperature field of the blade without considering the wear,it is found that the wear of the blade surface has obvious effect on the stress field and temperature field.Therefore,the influence of blade wear on the reliability of the blade should be considered.(3)The main factors affecting the friction and wear properties of the material were analyzed,and the variables needed to establish the prediction model of the blade wear were determined and quantified.The polynomial model of wear prediction was established by partial least squares method.The accuracy and effectiveness of the prediction model were tested.(4)The distribution of the variables in the wear prediction model and the relationship between the wear volume and the number of rubs were analyzed.The wear reliability model under the condition of linear relationship between wear accumulation and rubbing times was established.The Monte Carlo method was used to sample the variables obeying the normal distribution.The curves of the wear reliability of the blade with the number of rubbing were calculated under different working conditions;(5)Based on the stress field and the temperature field of the wear blade,the fatigue reliability under the specified life was calculated using the fatigue software,and compared with the wear reliability of the blade to evaluate the reliability of the blade comprehensively...