Temat: temperature-dependent properties

Skocz do pozycji: 1.

Tytuł:: Thermal buckling of temperature-dependent functionally graded Timoshenko beams
Autorzy:: Chen, Wei-Ren
Chen, Chun-Sheng
Chang, Heng
Tematy:: thermal buckling
functionally graded material
transformed-section method
temperature-dependent properties; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/139902.pdf Link otwiera się w nowym oknie
Opis:: Thermal buckling behavior of a functionally graded material (FGM) Timoshenko beam is studied based on the transformed-section method. The material and thermal properties of the FGM beam are assumed to vary across the beam thickness according to a power-law function, a sigmoid function and an exponential function. The results of buckling temperature for the FGM beams with respective temperature-dependent and temperature-independent properties under uniform and non-linear temperature rises are presented. Some results are compared with those in the published literature to verify the accuracy of the present work. The effects of the material distributions, temperature fields, temperature-dependent properties and slenderness ratios on the thermal buckling behaviors of FGM beams are discussed. It is believed that the present model provides engineers with a simple and effective method to study the effects of various parameters of the FGM beam on its thermal buckling behavior.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Magnetic characterization of the nickel layer protecting the copper wires in harsh applications
Autorzy:: Roger, D.
Duchesne, S.
Iosif, V.
Tematy:: high temperature motor winding
nickel diffusion barrier
temperature dependent magnetic properties; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/140802.pdf Link otwiera się w nowym oknie
Opis:: High Temperature (HT°) motor coils open new perspectives for extending the applications of electrical motors or generators to very harsh environments or for designing very high power density machines working with high internal temperature gradients. Over a temperature of 300E°, the classic enameled wire cannot work permanently, the turn-to-turn insulation must be inorganic and made with high temperature textiles or vitro-ceramic compounds. For both cases, a diffusion barrier must protect the copper wire against oxidation. The usual solution consists of adding a nickel layer that yields an excellent chemical protection. Unfortunately, the nickel has ferromagnetic properties that change a lot the skin effect in the HT wire at high frequencies. For many applications such as aeronautics, electrical machines are always associated with PWM inverters for their control. The windings must resist to high voltage short spikes caused by the fast fronted pulses imposed by the feeding inverter. The nickel protection layer of the HTE inorganic wire has a large influence on the high frequency behavior of coils and, consequently, on the magnitude of the voltage spikes. A good knowledge of the non-linear magnetic characteristics of this nickel layer is helpful for designing reliable HT inorganic coils. The paper presents a method able to characterize non-linear electromagnetic properties of this nickel layer up to 500E°.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: The effect of temperature-dependent viscosity and thermal conductivity on velocity and temperature field: an analytical solution using the perturbation technique
Autorzy:: Panahi-Kalus, H.
Ahmadinejad, M.
Moosaie, A.
Tematy:: temperature-dependent material properties
laminar channel flow
anaytical solution
perturbation technique; Pokaż więcej
Wydawca:: Instytut Podstawowych Problemów Techniki PAN
Powiązania:: https://bibliotekanauki.pl/articles/38610956.pdf Link otwiera się w nowym oknie
Opis:: This paper proposes a general form of the perturbation expansion method for the governing equations of viscous flow coupled to the temperature evolution. The effect of the variations of viscosity and thermal conductivity with temperature on the temperature and velocity fields in a steady two-dimensional Couette–Poiseuille flow is examined. The presented analytical solution by the perturbation method is validated against a finite difference solution of the governing equations. The numerical and analytical solutions are in good agreement.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Modified Couple Stress Theory for Micro-Machined Beam Resonators with Linearly Varying Thickness and Various Boundary Conditions
Autorzy:: Zenkour, A. M.
Tematy:: microbeam
temperature dependent properties
modified couple stress analysis
linear varying thickness
mikrowiązka
właściwości zależne od temperatury
zmodyfikowana analiza naprężeń momentowych
liniowo zmienna grubość; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/139912.pdf Link otwiera się w nowym oknie
Opis:: This article employs the classical Euler–Bernoulli beam theory in connection with Green–Naghdi’s generalized thermoelasticity theory without energy dissipation to investigate the vibrating microbeam. The microbeam is considered with linearly varying thickness and subjected to various boundary conditions. The heat and motion equations are obtained using the modified couple stress analysis in terms of deflection with only one material length-scale parameter to capture the size-dependent behavior. Various combinations of free, simply-supported, and clamped boundary conditions are presented. The effect of length-to-thickness ratio, as well as the influence of both couple stress parameter and thermoelastic coupling, are all discussed. Furthermore, the effect of reference temperature on the eigenfrequency is also investigated. The vibration frequencies indicate that the tapered microbeam modeled by modified couple stress analysis causes more responses than that modeled by classical continuum beam theory, even the thermoelastic coupled is taken into account.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Transverse vibration analysis of nonlocal beams with various slenderness ratios, undergoing thermal stress
Autorzy:: Babaei, Alireza
Rahmani, Arash
Ahmadi, Isa
Tematy:: small-sized beam
nonlocal theory
temperature dependent properties
free vibration
lateral vibration
belka o małych rozmiarach
teoria nielokalna
właściwości zależne od temperatury
drgania swobodne
drgania boczne; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/139619.pdf Link otwiera się w nowym oknie
Opis:: In this paper, thermally-excited, lateral free vibration analysis of a small-sized Euler-Bernoulli beam is studied based on the nonlocal theory. Nonlocal effect is exerted into analysis utilizing differential constitutive model of Eringen. This model is suitable for design of sensors and actuators in dimensions of micron and submicron. Sudden temperature rise conducted through the thickness direction of the beam causes thermal stresses and makes thermo-mechanical properties to vary. This temperature field is supposed to be constant in the lateral direction. Temperatures of the top and bottom surfaces of the system are considered to be equal to each other. Governing equation of motion is derived using Hamilton’s principle. Numerical analysis of the system is performed by Galerkin’s approach. For verification of the present results, comparison between the obtained results and those of benchmark is reported. Numerical results demonstrate that dynamic behavior of small-sized system is been effected by temperature shift, nonlocal parameter, and slenderness ratio. As a result, taking the mentioned parameters into account leads to better and more reliable design in miniaturized-based industries.
Dostawca treści:: Biblioteka Nauki

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