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

Bednarz, Arkadiusz; Misiołek, Wojciech Z.

doi:10.20944/preprints202108.0273.v1

Cited by 3 publications

(1 citation statement)

References 25 publications

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“…On the other hand, the article [21] examined two areas of fatigue of riveted aluminum lap joints and T-breaks: mechanisms of crack initiation and development, and the impact of fatigue on joint stiffness. There are many studies on fatigue tests of aircraft components [4][5][6][7]. Their approach to determining fatigue data would also be appropriate for aluminum materials used to build riveted joints.…”

Section: Introductionmentioning

confidence: 99%

The visual research of changes in the geometry of a rivet joint for material model effect for simulation riveted joints made of EN AW 5251

Lubas¹

2022

TiAM

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The paper presents the results of a numerical analysis of a single-lap joint with a blind rivet and its geometrical verification by inside views from the experiment. The research aimed to determine how the results of numerical analyses (FEM) were influenced by the method of modeling the material model and how it relates to the experimental results. As part of the analyses, a discrete riveted model and material model: linear and nonlinear were constructed. The analyses took into account various load cases (500, 800, and 900 N) to better illustrate the relationship between the numerical and experimental results. A new methodology of visualizing changes in a riveted joint's geometry was used to validate the results. The technology of making riveted joint cross-sections was developed during a static tensile test. Samples of a single lap joint with blind rivets made of aluminum sheets were subjected to a shear load. Deformations were "frozen" during the test, and sections were prepared. The microscope photos allowed for the development of a method for visualizing the deformation of the hole and rivet. The numerical results (for various loads and various material configurations) were compared with the experimental results of geometric parameters (i.e. angles between sheets or other dimensions) on the riveted joint cross-sections. The obtained results help to understand the mechanism of failure of the blind rivet under load and the complex state of loads in various stages of deformation.

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Section: Introductionmentioning

confidence: 99%

The visual research of changes in the geometry of a rivet joint for material model effect for simulation riveted joints made of EN AW 5251

Lubas¹

2022

TiAM

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

et al. 2022

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The aim of this work was to numerically determine the influence of aerodynamic loads on the value of the resonant frequency of the compressor blade. The object of the research was the 1st stage compressor blade of the PZL-10W engine. As part of the research, analytical calculations of the resonance frequency were performed and compared with the literature ones (first, second, and third forms of forced vibrations). In the next step of the investigation, a computational model of the compressor stage (fluid domain and rotors) was built and FSI analysis was performed. This analysis was based on CFD modeling of the state of aerodynamic loads on the blade surfaces, and then these values were imported as external loads for the structural analysis, which was the basis for the modal analysis, in which the resonant frequency of the first three vibration modes was determined. As part of the analyzes, both the influence of aerodynamic loads and the rotational speed of the compressor rotor were verified. Thus, it was possible to evaluate the influence of both the rotational speed (and the arising centrifugal force) and the influence of the emerging aerodynamic load. The results obtained will allow for the assessment of the impact of the aforementioned operating conditions of the aircraft engine on the resonance frequency, which in turn may translate into the durability of critical components of the aircraft engine.

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Numerical Study on Vibration Response and Fatigue Damage of Axial Compressor Blade Considering Aerodynamic Excitation

Lin

et al. 2021

Metals

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Axial compressor blades with a deformed initial torsion angle caused by aerodynamic excitation resonated at the working speed and changed the rule of fatigue damage accumulation. The fatigue life of a blade has a prediction error, even causing serious flight accidents if the effect of torque causing damage deterioration of the blade fatigue life is neglected. Therefore, in this paper, a uniaxial non-linear fatigue damage model was modified using the equivalent stress with torsional shear stress, and the proposed fatigue model including the torsional moment was used to study the compressor blade fatigue life. Then, the blade numerical simulation model was established to calculate the vibration characteristics under complex loads of airflow excitation and a rotating centrifugal force. Finally, the blade fatigue life under actual working conditions was predicted using the modified fatigue model. The results show that the interaction between centrifugal and aerodynamic loads affects the natural frequency, as the frequencies in modes dominated by bending deformation decreased whereas those dominated by torsional deformation increased. Furthermore, the blade root of the suction surface showed stress concentration, but there is an obvious difference of stress distribution and amplitude between the normal stress and the equivalent stress including torsional shear stress. The additional consideration of the torsional shear stress decreased the predicted fatigue life by 4.5%. The damage accumulation rate changes with the loading cycle, and it accelerates fast for the last 25% of the cycle, when the blade fracture may occur at any time. Thus, the aerodynamic excitation increased the safety factor of blade fatigue life prediction.

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

Cited by 3 publications

References 25 publications

The visual research of changes in the geometry of a rivet joint for material model effect for simulation riveted joints made of EN AW 5251

The visual research of changes in the geometry of a rivet joint for material model effect for simulation riveted joints made of EN AW 5251

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

Numerical Study on Vibration Response and Fatigue Damage of Axial Compressor Blade Considering Aerodynamic Excitation

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