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Wyświetlanie 1-6 z 6
Tytuł:
Insight into Damping Sources in Turbines
Autorzy:
Moneta, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/24201180.pdf
Data publikacji:
2022
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
vibrations
blade
gas turbine
turbine engine
damping
FEM
Finite Element Method
transient analysis
explicit
friction damping
under-platform damper
optimization
sensitivity analysis
Opis:
Blade vibrations in aircraft engines are a significant challenge that must be overcome during the design and development of modern turbine engines. Vibrations lead to cyclic displacements and result in alternating stress and strain in undesired environments (high temperatures, erosion, corrosion of the surface, etc.). Under resonance conditions, stress amplitudes can increase and exceed their safety limits, and in extreme cases, can lead to engine failure. One method to reduce resonance vibrations is to increase damping in the turbine assembly. This paper presents and describes vibration damping sources in the turbine, including aerodynamic, material, and friction damping. Additionally, typical damping values for each damping component are presented and compared.
Źródło:
Fatigue of Aircraft Structures; 2022, 14; 69--82
2081-7738
2300-7591
Pojawia się w:
Fatigue of Aircraft Structures
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of Manufacturing Tolerances on Stress in a Turbine Blade Fir-Tree Root
Autorzy:
Moneta, Grzegorz
Jachimowicz, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/2105140.pdf
Data publikacji:
2020
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
fir-tree root
turbine
lock
blade
disk
manufacturing tolerances
Monte-Carlo simulations
Six Sigma
Low Cycle Fatigue
Design of Experiment
Opis:
Low Cycle Fatigue (LCF) is one of most common mechanisms behind turbine blade failures. The reason is high stress concentration in notch areas, like fir-tree root groves, which can cause cyclic stress beyond the safe threshold. The stress levels strictly depend on the manufacturing accuracy of the fir-tree lock (for both fitted together: blade root and disk groove). The probabilistic study aimed at determination of stress was performed using Finite Element Method (FEM) simulation on a population of 1000 turbine models (disk + blades +friction dampers), where fir-tree lock dimensions were sampled according to the normal distribution, within limits specified in the documentation. The studies were performed for different manufacturing quality levels: 3-Sigma, 6-Sigma and 3-Sigma with tolerance ranges reduced twice. Based on the results, the probabilistic distributions, probabilities and expected ranges of values could be determined for: material plastification, stress, strain, LCF lifetime, etc. The study has shown how each tooth of the root is loaded and how wide a stress range should be expected in each groove. That gives information on how the definition of tolerances should be modified to make the construction more optimal, more robust, with lower likelihood of damage, taking into account the cost-quality balance. It also shows how the Six Sigma philosophy can improve the safety of the construction, its repeatability and predictability. Additionally, the presented numerical study is a few orders of magnitude more cost- and time-effective than experiment.
Źródło:
Fatigue of Aircraft Structures; 2020, 12; 92--101
2081-7738
2300-7591
Pojawia się w:
Fatigue of Aircraft Structures
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Laboratory Diffraction Methods in Characterization of Elements Made By Additive SLM Methods - State of the Art
Autorzy:
Gadalińska, Elżbieta
Pawliszak, Łukasz
Moneta, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/2105183.pdf
Data publikacji:
2021
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
X-ray diffraction
residual stress measurements
additive manufacturing
SLM
Opis:
The greatest challenge of widely developed incremental manufacturing methods today is to obtain, as a result of the manufacturing process, such components that will have acceptable strength properties from the point of view of a given application. These properties are indirectly determined by three key characteristics: the level of surface residual stress, the roughness of the component and its porosity. Currently, the efforts of many research groups are focused on the problem of optimizing the parameters of incremental manufacturing so as to achieve the appropriate level of compressive residual stress, the lowest possible porosity and the lowest possible roughness of parts obtained by 3D methods. It is now recognized that determining the level of these three parameters is potentially possible using experimental X-ray diffraction methods. The use of this type of radiation, admittedly, is only used to characterize the surface layer of elements, but its undoubted advantage is its easy availability and relatively low cost compared to experiments carried out using synchrotron or neutron radiation.
Źródło:
Fatigue of Aircraft Structures; 2021, 13; 72--80
2081-7738
2300-7591
Pojawia się w:
Fatigue of Aircraft Structures
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Laser Powder Bed Fusion and Selective Laser Melted Components Investigated with Highly Penetrating Radiation
Autorzy:
Gadalińska, Elżbieta
Pawliszak, Łukasz
Moneta, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/2105190.pdf
Data publikacji:
2021
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
neutron diffraction
synchrotron diffraction
residual stress measurements
additive manufacturing
SLM
LPBF
Opis:
Methods of incremental manufacturing, i.e. 3D printing, have been experiencing significant growth in recent years, both in terms of the development of modern technologies dedicated to various applications, and in terms of optimizing the parameters of the process itself so as to ensure the desired mechanical and strength properties of the parts produced in this way. High hopes are currently being pinned on the use of highly penetrating types of radiation, i.e. synchrotron and/or neutron radiation, for quantitative identification of parameters characterizing objects produced by means of 3D printing. Thanks to diffraction methodologies, it is feasible to obtain input information to optimize 3D printing procedures not only for finished prints but also to monitor in situ printing processes. Thanks to these methodologies, it is possible to obtain information on parameters that are critical from the perspective of application of such obtained elements as stresses generated during the printing procedure itself as well as residual stresses after printing. This parameter, from the point of view of tensile strength, compression strength as well as fatigue strength, is crucial and determines the possibility of introducing elements produced by incremental methods into widespread industrial use.
Źródło:
Fatigue of Aircraft Structures; 2021, 13; 81--98
2081-7738
2300-7591
Pojawia się w:
Fatigue of Aircraft Structures
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental and Numerical Stress State Assesment in Refill Friction Stir Spot Welding Joints
Autorzy:
Gadalińska, Elżbieta
Kubit, Andrzej
Trzepieciński, Tomasz
Moneta, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/2105194.pdf
Data publikacji:
2021
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
RFSSW
X-ray diffraction
finite elements modelling
stress state
aluminium alloys
Opis:
Refill Friction Stir Spot Welding (RFSSW) is a technology used for joining solid materials that was developed in Germany in 2002 by GKSS-GmbH as a variant of the conventional friction stir spot welding (FSSW) [1]. In the RFSSW technology, the welding tool consists of a fixed outer part and rotating inner parts, which are called a pin and a sleeve. The tool for RFSSW is designed to plasticize the material of the parts to be joined by means of a rotary movement. The design of the tool allows independent vertical movement of both elements of the welding tool. This allows obtaining spot welds without creating holes that could weaken the structure. The main advantage of RFSSW is the potential for replacing the technologies that add weight to the structure or create discontinuities, such as joining with screws or rivets. Thus, RFSSW has great potential in the automotive, shipbuilding and aviation industries. Furthermore, the technology can be used to join different materials that could not be connected using other joining methods. The main objective of this work is to understand the physical and mechanical aspects of the RFSSW method - including the residual stress state inside the weld and around the joint. The results of the investigations can help to determine optimal parameters that could increase the strength and fatigue performance of the joint and to prove the significant advantage of RFSSW connections over other types of joints. The work assumes the correlation of two mutually complementary investigation methods: numerical analyses and experimental studies carried out with diffraction methods. The comparison between numerical and experimental results makes potentially possible the determination of degree of fatigue degradation of the material by observing the macroscopic stress state and the broadening of the diffraction peak width (FWHM), which is an indicator of the existence of micro-stress related to the dislocation density and grain size.
Źródło:
Fatigue of Aircraft Structures; 2021, 13; 54--71
2081-7738
2300-7591
Pojawia się w:
Fatigue of Aircraft Structures
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Insight Into Vibration Sources in Turbines
Autorzy:
Moneta, Grzegorz
Jachimowicz, Jerzy
Pietrzakowski, Marek
Doligalski, Adam
Szwedowicz, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/2105187.pdf
Data publikacji:
2021
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
vibrations
blade
gas turbine
turbine engine
strain gauge
tip timing
Additive Manufacturing
Opis:
Despite of nearly 100 years of turbine engine development and design, blade vibrations remain a great engineering challenge. The rotating turbine blades’ vibrations lead to cyclic oscillations, which result in alternating stress and strain in harsh environments of high temperature and pressure. In modern aeroengines, high hot flow velocities might generate erosion and corrosion pitting on the metal surfaces, that leverage remarkably mean stresses. The combination of both mean and alternating stresses can lead to unexpected engine failures, especially under resonance conditions. Then, alternating stress amplitudes can exceed the safety endurance limit, what accelerates the high cyclic fatigue leading quickly to catastrophic failure of the blade. Concerning the existing state-of-the-art and new market demands, this paper revises forced vibrations with respect to excitation mechanisms related to three design levels: (i) a component like the blade design, (ii) turbine stage design consisting of vanes and blades and (iii) a system design of a combustor and turbine. This work reviews the best practices for preventing the crotating turbine and compressor blades from High Cyclic Fatigue in the design process. Finally, an engine commissioning is briefly weighed up all the pros and cons to the experimental validations and needed measuring equipment.
Źródło:
Fatigue of Aircraft Structures; 2021, 13; 40--53
2081-7738
2300-7591
Pojawia się w:
Fatigue of Aircraft Structures
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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