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Wyszukujesz frazę "stress fatigue" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
X-ray stress measurements in the institute of aviation possibilities and examples
Autorzy:
Gadalińska, E.
Malicki, M.
Powiązania:
https://bibliotekanauki.pl/articles/242492.pdf
Data publikacji:
2018
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
X-ray diffraction
residual stress measurements
fatigue
Opis:
From the point of view of the airplane construction, its fatigue lifetime and exploitation process, the stress states and levels are of crucial importance. The most appropriate experimental methods to determine stress values are diffraction methods with different radiation type employed. These methods allow the determination of the elastic lattice deformation and distortion (effectively the stress state) from the displacement and broadening of the diffraction peak. Diffraction methods are widely known as the experimental methods for determining not only the stress values but also the elastic properties of polycrystalline materials (also of all alloys types used in the aerospace industry). The advantages of diffraction experiments result from their non-destructive character and the possibility to obtain absolute values of stresses in different phases of each type of crystal material (the measurements are performed selectively only for crystallites contributing to the measured diffraction peak, i.e. for the grains having lattice orientations for which the Bragg condition is fulfilled). In the frame of this work, the laboratory possibilities of the Institute of Aviation in this area are presented as well as the exemplary results of stress measurements performed there.
Źródło:
Journal of KONES; 2018, 25, 3; 159-166
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of residual stress distribution in riveted lap joint under tension
Autorzy:
Wronicz, W.
Powiązania:
https://bibliotekanauki.pl/articles/245195.pdf
Data publikacji:
2018
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
joint
rivet
fatigue
residual stress
finite element
Opis:
Riveted joints are a common location of fatigue cracks in aircraft metal structures. Fatigue life of such joints as well as a place of cracks nucleation is strongly influence by a stress distribution in sheets, which is a result of residual stresses (mainly after riveting) and stresses induced by external loads. Stress distribution in two-row lap joint was investigated with the use of Finite Element Method. The joint consist of two 1.5 mm sheets and two protruding rivets with diameter equal to 4 mm, made of 2024 T3 (sheets) and 2117 T4 (rivets) aluminium alloys. The simulations covered a riveting process and tensile stages. The 3D models of joint with the universal rivets and with the brazier, rivets with a compensator were prepared. Elastoplastic material properties as well as geometric nonlinearity and contact phenomena were included. The results of simulations show that the residual stress distribution after release of tensile loading varies significantly from the distribution after riveting only. This fact should therefore be taken into account in a fatigue life estimation of such joints performed based on a FE calculation. The paper presents also the influence of the analysed rivet geometry on the stress distribution at the sheets faying surfaces.
Źródło:
Journal of KONES; 2018, 25, 4; 455-462
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fatigue strength of wood polymer composite
Autorzy:
Kyzioł, L.
Powiązania:
https://bibliotekanauki.pl/articles/242494.pdf
Data publikacji:
2014
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
modified wood
mechanical properties
fatigue strength
device to inflict plane stress
Opis:
This paper presents the results of a study on the fatigue strength in pendulum bending natural and modified pinewood. The contents of polymethyl methacrylate (PMMA) were determined in wood-polymer for mechanical and rheological properties. The study of the bending fatigue strength and creep was realized on suitably prepared samples and research positions. Test results were documented in the form of charts and scraps. Differences in the decay of the natural and modified wood samples were observed after the attempt of the fatigue strength. The various mechanical properties of the sapwood, hardwood, and the polymer, influence on the stiffness of the individual components and consequently the whole composite. The process of fatigue degrades the structure of natural wood and wood polymer composite, the result is a gradual reduction of its stiffness. The Study of the creep behaviour was realized in stress in the sample of the level of 30% of the tensile strength. The samples were loaded longitudinally and transversely to the direction of the fibres. Significant differences of composite deformations were observed both as for the direction of the loaded fibres as well as the natural and modified wood. The character of changes in the fatigue strength and creep behaviour of the studied materials is implies to the influence of the polymer content on mechanical properties of modified wood. The tests carried out on account of the possibility of using wood polymer composite in sea constructions. Research carried out in connection with the possibility of the use of wood polymer composite marine construction. Modified wood can be used for keel blocks, decks, fender beam, bearings cantilevered shaft lines and the construction of yachts.
Źródło:
Journal of KONES; 2014, 21, 1; 139-146
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A method of estimating the risk of a catastrophic failure to engines rotating members as related to fatigue - an outline
Autorzy:
Tomaszek, H.
Żurek, J.
Jasztal, M.
Powiązania:
https://bibliotekanauki.pl/articles/243106.pdf
Data publikacji:
2007
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
risk of failure
fatigue
load spectrum
probability density
stress intensity factor
Opis:
The paper has been intended to introduce a probabilistic method to estimate - from the standpoint of fatigue - the risk of a catastrophic failure to rotating (moving) members of an aircraft engine, i.e. to compressor blades. It has been assumed that there is a hidden defect in the material's structure, which initiates a small-size crack. Load-affected, the crack keeps growing. The crack propagation dynamics, when approached in a deterministic way, remains consistent with the Paris formula. The crack growth is effected by some random load characterised with the servicing load spectrum. While determining the load spectrum, all possible operational events are taken into account, excluding ones that could result in an immediate damage to the component. It has been assumed that random instances of load increase, which may result in an immediate damage, compose a separate set of events; hence, they have not been taken into account in this model. A partial differential equation of the Fokker-Planck type has been used to describe randomly approached dynamics of crack propagation. Having solved this equation enables a density function of the fatigue crack length to be found. This function, in turn, has been used to determine the risk of a catastrophic failure to a compressor blade. Furthermore, this function can also be used to find safe service life of the structure under consideration.
Źródło:
Journal of KONES; 2007, 14, 2; 505-511
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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