Temat: stress, - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: The influence of temperature and strain rate on the strengthening of metallic materials
Autorzy:: Kyzioł, L.
Powiązania:: https://bibliotekanauki.pl/articles/244257.pdf
Data publikacji:: 2016
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: strengthening materials
dislocations
athermic stress
mechanical threshold stress (MTS)
Opis:: Extensive literature indicates that the effect of strengthening materials is related to their structural construction. The structure of the metallic material exhibits the greatest strengthening effect when there is a very limited movement of dislocations and their movement is completely blocked due to numerous obstacles [1, 3, 6-9, 12, 15, 16]. In this paper strain, rate and temperature dependences of yield strength of metallic materials are presented. The effect of temperature and strain rate on the value mechanical threshold stress is determined. In addition, the effect of temperature on the Kirchhoff modulus and Burgers vector is determined. The interaction of dislocations with grain boundaries causes additional stress – athermal stress causing the strengthening of the structure. The term “athermal” implies that thermal activation is unable to assist the dislocation past these obstacles. The strengthening of metallic materials is related to the dimensions of the grains, which influence the athermic stress. The calculations of mechanical threshold stress and other parameters of the structure of the material allow for easier understanding of the strengthening of the material loaded with temperature and strain rate. The largest strengthening occurs in pure metals and their alloys in the case of the total blocking of dislocation motion. This process takes place when the temperature is 0 K or at very high strain rates. The metal demonstrates the greatest effort, which is called mechanical threshold stress (MTS) [5].
Źródło:: Journal of KONES; 2016, 23, 1; 199-206
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Stress-corrosion resistance of the EN AW-AlZn5Mg1,5CuZr alloy in different heat treatment states
Autorzy:: Kyzioł, L.
Powiązania:: https://bibliotekanauki.pl/articles/258610.pdf
Data publikacji:: 2013
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:: heat treatment
stress corrosion
alloy structures
corrosion resistance
Opis:: The effect of heat treatment of the plastically worked 7000 series Al-Zn-Mg aluminium alloy system on its stress-corrosion resistance is examined. For the same chemical constitution, the effect of heat treatment on mechanical and corrosion properties of Al-Zn-Mg alloys systems is remarkable. It was proved that a parameter having significant effect on corrosion properties of the alloy is the rate of alloy cooling after heat treatment. This conclusion is confirmed by observation of structural forms which fully reflect mechanical and corrosion properties of the alloy.
Źródło:: Polish Maritime Research; 2013, 4; 39-44
1233-2585
Pojawia się w:: Polish Maritime Research
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Stress distribution in an anisotropic beam subjected to load
Autorzy:: Kyzioł, L.
Powiązania:: https://bibliotekanauki.pl/articles/241691.pdf
Data publikacji:: 2018
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: isotropic material
anisotropic material
beam deflection
stress distribution in the beam
Opis:: The article presents the physical equations describing the isotropic and anisotropic materials. Orthotropic material and monotropic are special varieties of anisotropy. Constructional steel, pine wood and polyester-glass composite were tested. The beams were made from these materials. The beams were subjected to external loads. The external load caused internal forces in beams. Calculations of stress distribution were carried out by finite element method (Patran – Nastran software). The calculation results allowed for precise illustrate the distribution of stress especially in layered materials. The load is basically a transmitted through the strong layers of composite. This is illustrated in the figures. Wood is materials of a layered structure and is classified as inhomogeneous materials. Whereas steel is considered as a homogeneous material. Passing from the level of microscopic inhomogeneity to the macroscopic homogeneous level is called homogenization. This method formulates the macroscopic description by homogenizing microscopic properties. For the purpose of mathematical description of a material, the real centre can be substituted by a homogeneous centre. The homogenization method is commonly used to describe the properties of rocks, wood, composites, reinforced concrete, as well as human osseous tissues. The description of the mechanical properties of isotropic materials is based on the theory of elasticity, while the anisotropic materials are based on the anisotropic theory of elasticity. Calculations of anisotropic materials are quite complicated (large number of physical quantities) and sometimes-approximate results are obtained.
Źródło:: Journal of KONES; 2018, 25, 2; 207-214
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

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

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Skocz do pozycji: 5.

Tytuł:: Shear stress in measuring section of the sample with modified wood
Autorzy:: Kyzioł, L.
Powiązania:: https://bibliotekanauki.pl/articles/242608.pdf
Data publikacji:: 2016
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: modified wood
mechanical properties
Iosipescu shear test
device to inflict plane stress
Opis:: The shear strength of anisotropic materials is carried out on the special samples and on the appropriate instrumentation. Research conducted to obtain a homogenous state of the shear stress in the plane sample is difficult, and involve numerous occurrence of additional stress. Therefore, it is difficult to determine the shear strength. The wood composites are classified as orthotropic materials. In addition, are composed of the layers early wood and latewood. The layers have different thicknesses and exhibit different strength properties. The principal method for determining the shear stress is the trial of twisting of thin-walled tubes. Production of the pipe samples from the wood to determine the shear stress is impossible, due to annual rings. Beginning of destruction of samples under load was registered by a prototype device. This device makes the realization of plane state of stress in the sample possible. The position of the axis of the sample relative to the direction of the load can be varied. Such configuration axle of the sample to the loading direction, allows to perform, also stretching or compression besides to shear. The tests were performed for the natural wood and surface modified wood. The paper presents an original method and device designed to determine the shear strength of anisotropic materials on the example of natural wood and a surface modified wood.
Źródło:: Journal of KONES; 2016, 23, 1; 193-198
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Description of strength of wood composite in compound state of load
Autorzy:: Kyzioł, L.
Powiązania:: https://bibliotekanauki.pl/articles/950148.pdf
Data publikacji:: 2017
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: compound state of stress
modified wood
effort criterion
strengthening of the material
Opis:: All constructions are subject to the most compound loads and therefore a suitable effort hypothesis should be used for their calculation. For anisotropic materials, a hypothesis should be used to describe the properties of such materials. In the work have been shown the strength of the layers composite on the example of construction wood in a compound stress state. Wood composite is an orthotropic material. Wood is composed of alternating layers of soft wood and hard wood. Single layers are monotropic material. The use of a stress hypothesis, which describes the strength of an orthotropic material, requires will make an investigation. Studies is purposed to determine the tensile strength along and across the fibres. The compressive strengths along and across the fibres and the shear strength. Particularly the determination of shear strength requires special tooling so that in the case of flat samples in the measuring part it is possible to determine the shear stresses. Therefore, a research stand was designed and constructed. Known stress hypotheses for anisotropic materials have been analysed. The analysis showed that the strength of the wood composite could be described by the Tai-Wu stress hypothesis. Based on the results of the research, numerical calculations were performed. Calculations allowed determining the distribution of stresses in the sample measuring part. The results tests and numerical calculations have shown that obtaining a homogeneous stress (shear) condition for anisotropic materials is very difficult. Wood belongs to materials whose mechanical properties depend on many parameters, so the description of the effort of this material is a compound issue. Studies have shown that wood reinforcement by polymer saturation is best suited to the compressed loaded structures.
Źródło:: Journal of KONES; 2017, 24, 3; 161-165
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Analysis of fracture toughness of structural timber. Part I. Theory and experimental tests
Autorzy:: Kyzioł, L.
Powiązania:: https://bibliotekanauki.pl/articles/258732.pdf
Data publikacji:: 2010
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:: anisotropic material
anisotropic material cracking
CAD specimens
test stand
complex loading
stress distribution
Opis:: This paper presents fundamentals of fracture mechanics of anisotropic materials. Fracture toughness of anisotropic materials, e.g. structural timber, depends a. o. on state of stress, environment, temperature and changes due to ageing, therefore in such materials cracking process runs in various ways. Timber is characterized by eighteen coefficients which determine its fracture toughness in contrast to metals for which this number is as low as three. In this part of considerations a way of conducting the tests of specimens subjected to cracking as well results of the tests of natural and modified timber, are presented.
Źródło:: Polish Maritime Research; 2010, 3; 53-58
1233-2585
Pojawia się w:: Polish Maritime Research
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Determining strength of the modified wood
Autorzy:: Kyzioł, L.
Powiązania:: https://bibliotekanauki.pl/articles/258910.pdf
Data publikacji:: 2008
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:: wood modification
wood-polymer composite
Iosipescu specimen
stress distribution in the specimen under load
Opis:: The article presents results of investigations of the effect of pinewood modification with methyl polymethacrylate on the anisotropy of its strength in complex stress conditions. The investigations aimed at determining the resistance of the examined wood to stretching, compression, stretching with shear, and compression with shear. For the investigations oriented on shear, shear with stretching, and shear with compression, a special specimen was prepared which differs by notch geometry from a typical Iosipescu specimen. A new test machine is described in the article, which is equipped with special specimen holders to perform investigations in complex stress conditions. Crack patterns recorded for the natural and modified wood are presented. For all tests, numerical FEM simulations were performed to obtain stress distributions inside the specimens. The calculated stress distributions were visualised as contour line projections for the natural and modified wood.
Źródło:: Polish Maritime Research; 2008, 2; 40-25
1233-2585
Pojawia się w:: Polish Maritime Research
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Wpływ temperatury i szybkości odkształcania na charakterystyki wytrzymałościowe materiałów metalicznych
The Influence of Temperature and Strain Rate on the Strength Characteristics of Metallic Materials
Autorzy:: Kyzioł, L.
Powiązania:: https://bibliotekanauki.pl/articles/341834.pdf
Data publikacji:: 2017
Wydawca:: Uniwersytet Morski w Gdyni. Wydawnictwo Uniwersytetu Morskiego w Gdyni
Tematy:: odkształcenia materiałów
szybkość odkształcania
naprężenie progowe
umacnianie materiałów
strain of materials
strain rate
mechanical threshold stress
strengthening materials
Opis:: Przedstawiono różnicę pomiędzy odkształcaniem quasi-statycznym a dynamicznym materiałów metalicznych. Dla dużych szybkości odkształceń naprężenie (odkształcenie) w ciałach przemieszcza się z określonymi prędkościami jako fala. Odkształcanie dynamiczne związane jest z rozchodzeniem się fali, natomiast statyczne można rozpatrywać jako okresowe stany równowagi. Przy niedużych szybkościach odkształceń ciało pozostaje w warunkach izotermicznych, a dla dynamicznych procesów odkształcenia jest to proces adiabatyczny. Wprowadzono pojęcie naprężenia progowego ?^ (ang. mechanical threshold stress), które jest maksymalną wartością naprężenia dla danego rodzaju materiału metalicznego w temperaturze 0 K lub, ekwiwalentnie, przy nieskończenie dużej szybkości odkształcenia. Z obniżeniem temperatury następuje zmniejszenie się ruchliwości dyslokacji. Zjawisko to jest związane ze spadkiem zdolności poruszania się atomów w sieci w obniżonych wartościach temperatury, których ruchy drgające całkowicie ustają w temperaturze 0 K. Pojęcie naprężenia progowego zostało zobrazowane za pomocą przykładu obliczeniowego.
The article presents the difference between the quasi-static and dynamic strain of metallic materials. At the high strain rate, stress (strain) in metallic materials moves with specified velocities as a wave. The dynamic deformation is related to the propagation of the wave while the static deformation can be seen as temporary states of equilibrium. At small speed deformations, the body remains in isothermal conditions, while the dynamic strain processes are the adiabatic processes. The concept of the mechanical threshold stress ?^ has been introduced, which is the maximum stress value for the particular type of metallic material for 0 K or, equivalently, infinitely high speed deformation. With the decrease of the temperature, there is a reduction of the dislocation mobility. This phenomenon is associated with a decrease in mobility of atoms in the network at reduced temperatures, which vibrating movement completely stops at 0 K. The concept of the mechanical threshold stress has been illustrated using the calculation example.
Źródło:: Zeszyty Naukowe Akademii Morskiej w Gdyni; 2017, 100; 109-119
1644-1818
2451-2486
Pojawia się w:: Zeszyty Naukowe Akademii Morskiej w Gdyni
Dostawca treści:: Biblioteka Nauki

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