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1

Transverse vibration analysis of nonlocal beams with various slenderness ratios, undergoing thermal stress

Babaei Alireza, Rahmani Arash, Ahmadi Isa

Archive of Mechanical Engineering

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2019

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Vol. LXVI, nr 1

5--24

EN

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.

2

Modified Couple Stress Theory for Micro-Machined Beam Resonators with Linearly Varying Thickness and Various Boundary Conditions

Zenkour A. M.

Archive of Mechanical Engineering

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2018

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Vol. LXV, nr 1

43--64

EN

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.

3

SH waves in a layer with temperature dependent properties

Matysiak S. J., Mieszkowski R., Perkowski D. M.

Acta Geophysica

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2014

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Vol. 62, no. 6

1203--1213

EN

The paper deals with the problem of SH harmonic wave propagation in an elastic layer with temperature dependent properties. The shear modulus and mass density are linearly dependent on temperature. The layer is rested on a rigid foundation and the upper boundary is free of loadings. The boundary planes are kept at different constant temperatures. The wave velocity and amplitude of stresses are analysed.

4

Generalized Thermoelasticity Plane Waves in Rotating Media with Thermal Relaxation under the Temperature Dependent Properties

Othman M. I. A.

Mechanics and Mechanical Engineering

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2005

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Vol. 9, nr 2

89--110

EN

A two-dimensional coupled problem in generalized thermoelasticity for rotating media under the temperature dependent properties is studied. The problem is in the context of the Lord-Shulman's theory with one relaxation time. The normal mode analysis is used to obtain the expressions for the temperature distribution, displacement components and thermal stresses. The resulting formulation is applied to two different problems. The first concerns the case of a heat punch moving across the surface of a semi-infinite thermoelastic half-space subjected to appropriate boundary conditions. The second deals with a thick plate subject to a time-dependent heat source on each face. Numerical results are illustrated graphically for each problem considered. Comparisons are made with the results obtained predicted by the two theories in case of absence of rotation.