Experimental investigations of fatigue cracking behavior of LC9 aluminum alloy (AA LC9) subjected to elevated temperature were conducted with scanning electron microscope (SEM). Results indicate elevated temperature is important for the fatigue crack growth of AA LC9. Based on small crack growth, crack growth rate for AA LC9 is characterized.

This paper takes the 2nd HP turbine disc of an aeroengine as research object, construct its finite element model in software-Patran. According to the work environment of 2nd HP turbine disc, the boundary conditions of stress field analysis and temperature field analysis are confirmed. Based on the finite element theory of thermal analysis and structure analysis, we use finite element software-Nastran to analyze centrifugal stress and thermal stress. Numerical calculation method was used to fit the data and finally we got the thermal elastic stress field. According to the computed results, the life assessment points of disc were confirmed. The static strength of 2nd HP turbine disc was tested based on the EGD-3 criterion. All the work established the foundation for subsequent life analysis.

A new neighborhood variable precision rough set modal is presented in this paper. The modal possesses the characteristics of neighborhood rough set and variable precision rough set, so it can overcome shortcomings of classic rough set which only be fit for discrete variables and sensitive to noise. Based on giving the definitions of approximate reduction, lower and upper approximate reduction, lower and upper distribution reduction, two kinds of algorithms to confirm lower and upper distribution reduction were advanced. The modal was applied to diagnose one frequency modulated water pump vibration faults. The result shows the modal is more suitable to engineering problems, because it can not only deal with continues variables but also be robust to noise.

Study the effect of the blade’s aspect ratio and thickness on rotating vibration according as modulating frequency can reduce the resonance vibration of the blades. Research the modal analysis of the blades of the aero-engine. Apply the software of a finite element method (FEM) to simplify calculating process. Establish three finite element models of the blade. Calculate and analyze the natural frequency and mode of each blade. Analyze the local resonance which is caused by the wake flow exciting force in the different conditions of the engine. The structure of the blades should be right for the engine conditions which make the vibration frequency of the blades out of the resonance vibration scope.