Fatigue Life Evaluation And Damage Analysis Of Aeroengine Low Pressure Compressor Disk

Compressor disk is an important part of aero-engine.Its main function is to install the blade and transmit power.The damage and failure of the disk will cause serious consequences of the aircraft which cannot be assessed.The main failure modes of the disk are low cycle fatigue,plastic deformation,crack damage and so on.And low cycle fatigue failure is the primary fault mode of the disk.With the development of modern aero-engine,the push weight ratio increased gradually.So the stress of compressor disk increased greatly.At present,the international major aviation country have a complete set of evaluation system of aero-engine,and our country is still relatively backward in this respect.In order to adapt to the development of aero-engine,and improve the design and manufacture level of our country,we must research on life prediction and damage analysis of the compressor disk.It is of great practical significance to strengthen the research of the aero-engine disk.In view of the above problems,through the theoretical and simulation analysis,the research of compressor disk from the direction of fatigue life and fatigue damage is proposed in this paper.The main research contents of this paper include:(1)The static analysis of the disk is carried on.The structure model of the disk is constructed in the three-dimensional drawing software,and the finite element statics analysis is carried out.Taking the disk-blade system as a whole elastic and plastic analysis object,the influence of the mortise and tenon contact is considered mutually.In this section,the dangerous part of the disk and the stress and strain state of the dangerous part are determined.(2)The simulation design of disk is carried on.In this paper,the structure and design scheme of the simulation is established.The design criteria of simulation is three principal stress and stress gradient.The design variables,state variables and optimization functions are designed by using the idea of optimal design,for determining the structure size to accord with the design criteria.The design process of the simulation is integrated to make the simulation software with user interaction function.(3)The fatigue life of disk is carried on.The existing methods of life prediction are summarized.Based on the finite element method,the fatigue analysis of the disk is carried out,and the local stress and strain variation law of the disk under the action of alternating load is simulated.According to the fatigue constant of the material,the strain life curve of the disk material is fitted,and the life of the disk is evaluated by the local stress strain method.(4)The research on the damage of disk is carried on.The finite element model of 3D surface crack is explored.By using the sub model technique,a disk model with three dimensional surface crack is established.The crack on the dangerous part of the disk is analyzed and the stress intensity factor is calculated.The crack extension is simulated,and the growth law of the surface crack is studied.