Numerical and Experimental Assessment of the Effect of Residual Stresses on the Fatigue Strength of an Aircraft Blade

Abstract

The work presents the results of numerical fatigue analysis of a turbine engine compressor blade, taking into account the values of initial stresses resulting from surface treatment-shot-peening. The values of the residual stresses were estimated experimentally using X-ray diffraction. The paper specifies the values of the residual stresses on both sides of the blade and their reduction due to cutting through the blade-relaxation. The obtained values of the residual stresses were used as initial stresses in the numerical fatigue analysis of the damaged compressor blade, which was subjected to resonant vibrations of known amplitude. Numerical fatigue ε-N life analysis was based on several fatigue material models: Manson’s, Mitchell’s, Baumel-Seeger’s, Muralidharan-Manson’s, Ong’s, Roessle-Fatemi’s, and Median’s, and also on the three models of cyclic hardening: Manson’s, Xianxin’s, and Fatemi’s. Because of this approach, it was possible to determine the relationship between the selection of the fatigue material ε-N model and the cyclic hardening model on the results of the numerical fatigue analysis. Additionally, the calculated results were compared with the results of experimental research, which allowed for a substantive evaluation of the obtained results. These results are of great scientific and practical importance. The problem of determining the fatigue life of blades with defects operating under resonance vibrations is one of the original tasks in the field of fracture mechanics and experimental mechanics. The results obtained are of great importance in the aviation industry and can be used during engine maintenance and inspections to assess the suitability of blades with defects in terms of the needs of further work. This aspect of engineering maintenance is of great importance from the aircraft safety point of view.

Analysis of the effects of simplifications on the state of loads in a centrifugal compressor

“…Additionally, the compaction of discrete elements in the blade leaves and rounding zones were introduced. This action was taken to improve the quality of the numerical analysis results and to ensure the condition of a minimum of 3 elements along with the thickness of the blade 44 , 45 .…”

Numerical Investigation of the Influence of Aerodynamic Loads on the Resonant Frequency of a Compressor Blade Made of EI-961 Alloy

“…The tested blade weighs an average of 15.6 g [ 23 ] and was subjected to surface treatment (peening), which causes residual stresses on the surface of the blade, with values locally exceeding MPa (compressive stresses), significantly increasing the fatigue strength of the blade in question [ 24 ]. Similar solutions have been used globally in the structure of the rotor blades, also known as the critical elements of the engine.…”

“…The first stage blade of the PZL-10W compressor has been the subject of many experimental and numerical studies [ 8 , 23 , 24 , 25 ]. As part of experimental research, its fatigue life was tested depending on the damage or its absence.…”

The Concept and Preliminary Design of a New Drone Destined for Military Rescue/Medical Missions

“…At the stage of selecting the propulsion unit and propellers, there is a need to consider their fatigue strength. The issues of fatigue calculations for rotating objects are considered in [15,16].…”