Reliability-based Sensitivity And Robust Design Of Aero-engine Turbine Disk With Arbitrary Distribution Parameters

The turbine disk is a main component of aero-engine, the working environment of the turbine disk is very hash under high rotation speed, high temperature, high speed gas flow, high pressure. It also bears cyclic loadings of centrifugal force, thermal stress, aerodynamic force, external excitation and impact as well as dynamic forces. What’s more, the structure, service status and working environment of the impeller are very complicated. Duo to the randomness of the geometry dimension, load and material attribute of the turbine rotor systems, the failure of the turbine disk often leads to disastrous consequences. Therefore, it is urgent to pursue the research on the safety and reliability of the turbine disk.This thesis presents a research on structural reliability problem of the turbine disk under mutual influence between high rotate speed and high temperature, based on the reliability theory, reliability sensitivity technique and reliability-based robust design for mechanical structures.The main work of the thesis as follows,(1) The parametric model of the turbine disk is built, which could be automatically modified and rebuilt by changing the design parameters. In this case, the design efficiency would be greatly improved and the finite element simulation would be more flexible.(2) The thermal structure coupling analysis of the simplified turbine model was carried out. Duo to the circulation symmetry and the consistency of the load of the turbine disk, a1/72part of the whole model is built for simpilification, which could greatly reduce the analysis time and save resources. Though finite element (FE) analysis, the location of the maximum stress is consistent with that in experiment.(3) The stochastic finite element method (SFEM) and response surface method (RSM) have a wide application in reliability analysis of complex structural systems at present. In the thesis, a method for reliability analysis of the turbine disk by integrating the theories of stochastic finite element and response surface method is proposed. In the method, Back propagation network (BP network) was used to obtain the approximately explicit function of the response of the turbine disk with respect to the random variables. (4)In the conventional reliability design, the random variables are usually assumed to be normally distributed. In the engineering practice, there is always not enough data to determine the distribution of the random variables. However, it is relatively easy to estimate the first four moments of the random variables from the statistical data. In this thesis, the perturbation method and the fourth moment method were employed to present an approach for the reliability analysis of the turbine disk with arbitrary distribution parameters with known first four moments of basic random variables.(5) based on the the reliability design theory, the reliability sensitivity technique, the robust design method and the fourth moment technique, the problem of the turbine disk with arbitrary distribution parameters was extensively discussed, whereaftter the reliability sensitivity of the structure and the quality of turbine disk is reduced with the optimal structural parameters. The proposed method provides a theoretical basis for the reliability sensitivity analysis and reliability-based robust design of the turbine rotor.