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This paper proposes a novel solution for the radially FGM cylinder subjected to thermo-mechanical shock. By discretizing the state space equation in the spatial domain and applying the time marching technique based on central difference, a semi-analytical solution to the thermoelastic dynamic behavior of cylinders is developed. The proposed solution technique has two advantages, one is suitable for the arbitrariness of material properties varying in the radial direction, and the other is applicable to different boundary conditions. Numerical examples for the cylinders with different graded material properties and two different boundary conditions are examined. The obtained results not only verify the correctness and effectiveness of the present solution, but also demonstrate the flexibility of the present method. The influences of gradient functions and boundary conditions on dynamic behavior are clearly displayed. The solution method is convenient and practical, which may help to freely select the gradient function for the design of FGM cylinders under various conditions. [ABSTRACT FROM AUTHOR]

Buoyancy-driven flow and heat transfer characteristics of the solid/hollow cylinders with concave shapes were numerically analyzed in a turbulent regime. The effects of Ra , L / D , and D th / D on heat dissipation have been studied in the range of 1010 to 1012, 2 to 10, and 0.2 to 0.9, respectively. It has been found that the Nu ¯ increases with Ra for solid/hollow cylinders. For a hollow cylinder, Nu ¯ in is always higher than Nu ¯ out except at D th / D = 0.2. The Nu ¯ in of a hollow cylinder increases up to D th / D = 0.6, irrespective of the Ra , and L / D ratios thereafter reduced drastically has been observed. Whereas, at a low D th / D , and high Ra (i.e., Ra ≥ 1011), Nu ¯ out of a hollow cylinder significantly decreases with D th / D . However, it shows a marginal decrement at a high length-to-diameter ratio. For solid and hollow cylinders, the thermo-fluid dynamics have been delineated through the temperature contours, streamline patterns, and vortex generation at the inner as well as outer wall of the hollow cylinder. This numerical study also proposes a correlation for the Nu ¯ of the solid/hollow cylinders to have an accuracy ± 6 % of relevant parameters. [ABSTRACT FROM AUTHOR]

Based on fractional thermoelastic diffusion theory, an infinite hollow cylinder with variable thermal conductivity and diffusivity is studied. The inner surface of the hollow cylinder is free and subjected to thermal and chemical shocks, while the outer surface is fixed and adiabatic. The closed forms of dimensionless displacement, temperature, chemical potential, stress, and concentration in the Laplace transform domain are given by eigenvalue method. These physical quantities are then numerically obtained through the inverse Laplace transformation. The effects of fractional order parameters, variable thermal conductivity and diffusivity on these quantities are discussed. The present model may be helpful for better understanding the thermoelastic diffusion problems in actual engineering. [ABSTRACT FROM AUTHOR]

In this paper, a numerical axisymmetric elastic stress wave propagation analysis of the 2D-FGM hollow thick finite cylinder has been performed. The new accurate material distribution model based on Mori-Tanaka scheme and third-order transition function for 2D-FGMs has been implemented in the graded finite element method with higher-order quadrilateral elements. A non-uniform impulsive pressure has been applied on the one-third of the top inner cylinder wall. Consequently, different wave velocities and reflections from the boundaries have been observed due to the graded distribution of material along with two directions. Moreover, the effects of two-dimensional material property distributions on the stress wave propagations and displacements through the cylindrical wall at different locations have been studied systematically. Normalized effective stresses based on von-Mises criteria has been performed in comparison with the internal impulsive pressure amplitude to provide a measure of the cylinder wall response to the mechanical impact loading, the effective stresses are nearly 2.5 times the internal pressure loading amplitude, closed to the impact location. According to the results, 2D material property gradations has effected the stresses significantly. Alternatively, desired stress values can be achieved through optimal design and appropriate choice of property distribution. [ABSTRACT FROM AUTHOR]

With the application of tiny components in scientific research and daily life, heat conduction and structural shape change in solids have attracted the idea of researchers. So further refinement of the theoretical model of thermo-viscoelastic hollow cylinders with fractional-order derivatives is the fundamental purpose of this study and development of fractional-order thermoelasticity theory with fractional-order strains to provide theoretical foundations for some thermodynamic practical applications (e.g., pipeline transport of gases or liquids) and selection of elastic and viscoelastic materials. In this paper, the dynamic response of the inner and outer surfaces of an infinitely sizeable hollow cylinder under the action of thermal shock is examined based on the fractional-order two-phase hysteresis theory and viscoelasticity theory. Convective boundary conditions are imposed on the inner and outer surfaces of the hollow cylinder and there is no traction on the inner and outer surfaces. The governing equations of the problem are established and solved by the Laplace transform method. In the numerical calculations, firstly, the effects of viscoelastic parameters on heat transfer as well as the stability of material structure are examined; secondly, the effects of fractional-order strain parameters on the model and their variations are examined; and finally, the effects brought about by the selection of hysteresis factors are examined. The results show that the introduction of the fractional order strain parameter has an important effect on the generalized thermoelastic model, and the viscoelastic parameter has a significant effect on the physical field of the hollow cylinder, especially the displacement and stress. [ABSTRACT FROM AUTHOR]

Due to the extensive usage in the industry, the structural integrity of hollow cylinders is seen as a critical goal for stakeholders. Fracture is the most common failure mode for cylinders, which occurs due to crack propagation. Cracks can be found in single or multiple forms; when numerous, crack interaction occurs, which can exacerbate pressures beyond the material's resistance. This work uses Ansys software to examine double parallel interacting surface cracks on a hollow cylinder. The stress intensity factor (SIF) was used to describe the driving force that was used to characterize crack interaction for various crack geometries. To conduct extensive research, this study evaluated a wide range of crack aspect ratios as well as the relative depth of the crack. The findings of this study indicated that the shielding effect demonstrated parallel crack interaction. In addition, an empirical mathematical approach for predicting SIFs for double parallel cracks via single crack SIFs has been developed. The validation of the proposed model using performance evaluation metrics revealed an acceptable rate of error of less than 5%. [ABSTRACT FROM AUTHOR]

The stability and durability of concrete materials are essential factors in the construction industry. Environmental conditions, such as temperature affect the tensile strength and durability of concrete structures. This work investigates the thermodynamic behaviour of hollow cylindrical concrete using the finite element method (FEM). By deploying ANSYS®, the element mesh was created, and the temperature distribution inside the hollow cylinder was calculated. The effect of the hollowness of the concrete on its heat absorption is determined. The findings demonstrate that the temperature profiles changed radially throughout the concrete thickness. Moreover, it was discovered that the temperature distribution was impacted by the airflow into the cylinder. The numerical experiment in this study was essential in providing a comprehensive understanding of the behaviour of the concrete, particularly when exposed to higher heating rates. This study contributes to the knowledge of the performance and stability of concrete materials. It also demonstrates that the hollowness of the concrete enhances its heat-shielding performance. Furthermore, the inflow of air into the cylinder affects the temperature distribution, with a higher influx of air resulting in lower temperatures. These findings can be utilised to develop appropriate measures to enhance the performance and durability of concrete structures.

The flow-induced vibration of a circular cylinder with a hollow section that is mounted at the rear is investigated in this work via numerical simulation. The Reynolds number was limited in the range of 6918–1511 by using reduced velocity that corresponds to Ur = 2–12. Five typical center-to-center distance ratios L/D of 3, 4, 5, 6, and 7 and three hollow section positions of left bias, up bias, and middle of cylinder were selected. The displacement time history curve and short-time Fourier transform diagram show that when L/D = 3 and Ur = 3, the cylinder with the hollow position in the middle initially entered the main frequency vibration for 5.64 s, but when L/D = 4 and Ur = 6, the drag coefficient time history curve of the cylinder biased to the left and up at the hollow position demonstrated a "beating" phenomenon, and multiple frequency peaks appeared on the fast Fourier transform diagram. [ABSTRACT FROM AUTHOR]

Abstract The buoyancy-driven thermofluid dynamics of a solid/hollow cylinder with concave surfaces have been studied in a laminar regime ( 10 4 ≤ R a ≤ 10 8 ) using the finite-volume method to analyze the effects of L / D ( 2 ≤ L / D ≤ 10 ) , and D t h / D   ( 0.2 ≤ D t h / D ≤ 0.9 ) . Conservation equations for mass, momentum, and energy have also been solved in a 2-D axisymmetric geometry . Second-order upwind and central difference schemes have been deployed to discretize the convective and diffusive terms. Heat dissipation increases with R a irrespective of L / D for both cylinders. However, the N u ¯ total remains constant with the L / D ratio for a hollow concave cylinder N u ¯ i n increases with D t h / D ; whereas, N u ¯ out decreases. Multiple vortices appear at the outside surface at a low D t h / D (i.e. = 0.2), and these vortices almost disappear at high D t h / D (i.e. = 0.6), affecting the outside average Nusselt number from low to high. In all cases, N u ¯ out is higher than N u ¯ i n . The thermofluid dynamics of solid and hollow cylinders have been delineated through different countour and vector plots, and two correlations for Nu have been deveoped. [ABSTRACT FROM AUTHOR]

A one-dimensional problem of elastic diffusion for a hollow orthotropic multicomponent cylinder under the action of external pressure, which is uniformly distributed over its inner and outer surfaces is considered. The mathematical model includes a system of equations of elastic diffusion in a cylindrical coordinate system, which takes into account relaxation diffusion effects, implying finite propagation velocities of diffusion processes. The problem is solved by the method of equivalent boundary conditions. For this an auxiliary problem is considered, whose solution is obtained by expansion into series in terms of the eigenfunctions of the elastic-diffusion operator. The relations that connect the right parts of the boundary conditions of both problems are constructed. These relations represent a system integral equation. They are solved using quadrature formulas. A calculation example for a three-component hollow cylinder is considered. [ABSTRACT FROM AUTHOR]

The hollow cylinder with a large diameter is the typical shell structure in major engineering applications such as aviation, aerospace, ocean, and so on. Unlike the geometric properties of transportation pipe, the shell structure has a large size and short length. It is relatively difficult to detect damage globally. According to the abovementioned characteristics, a damage localization method based on helical sensor network is proposed in the current research work to locate the internal damage in large-scale hollow cylinder in which the sensors are arranged on the outer surface of the structure. The wavefront theory about flexural modes is fully explored to determine helical sensor network which is suitable for the full frequency spectrum and avoids the approximate estimation to the wave in plate. The flexible sensing paths and single mode excitation in helical sensor network also provide more possibilities for the damage localization in hollow cylinder. The verification method of circumferential orders based on the Fourier transform is developed by the normal mode expansion approach. To apply the helical sensor network of flexural mode in damage localization, the effective loading length of flexural modes is investigated using simulation. And the simulation and experiment both are conducted to locate the internal damage in hollow cylinders and verify the credibility of proposed localization method. The scale parameter and sensing path number are further investigated to determine the effect on location accuracy. [ABSTRACT FROM AUTHOR]

Based on the one-dimensional elastic theory, the radial vibrations of cylindrical isotropic embedded in an elastic medium are studied in the paper. The effect of the magnetic field of the radial vibrations of an elastic hollow cylinder with rotation is researched as well. The one-dimensional equation of elastodynamic is solved in terms of radial displacement. The frequency equation is obtained when the boundaries are free and fixed; the mixed boundary condition is numerically examined. The determination is concerned with the eigenvalues of the natural frequency of the radial vibrations in the case of harmonic vibrations. The effect of the magnetic field and rotation on the natural frequencies were explored. It was shown that the dispersion curves of guided waves were significantly influenced by the magnetic field and rotation of the elastic cylinder. Numerical results are given and graphically illustrated in each considered case. The natural frequencies and mode shapes are calculated numerically, and the effects of rotating, magnetic field, and variable thickness are discussed. It is observed that an increase of the magnetic parameter, as well as the rotation parameters, brings results closer to the classical cylinder theory results. Furthermore, the current study can be applied to the design of microplates and nanoplates and their optimal usage. The results indicate that the effects of the magnetic field and rotation are very pronounced. [ABSTRACT FROM AUTHOR]

In the present work, we implement a graded finite element analysis to solve the axisymmetric 2D hyperbolic heat conduction equation in a finite hollow cylinder made of functionally graded materials using quadratic Lagrangian shape functions. The graded FE method is verified, and the simple rule of the mixture with power-law volume fraction is found to enhance the effective thermal properties' gradation along the radial direction, including the thermal relaxation time. The effects of the Vernotte numbers and material distributions on temperature waves are investigated in depth, and the results are discussed for Fourier and non-Fourier heat conductions, and homogeneous and inhomogeneous material distributions. The homogeneous cylinder wall made of SUS304 shows faster temperature wave velocity in comparison to the ceramic-rich cylinder wall, which demonstrates the slowest one. Furthermore, the temperature profiles along the radial direction when n = 2 and n = 5 are almost the same in all Ve numbers, and by increasing the Ve numbers, the temperature waves move slower in all the material distributions. Finally, by tuning the material distribution which affects the thermal relaxation time, the desirable results for temperature distribution can be achieved. [ABSTRACT FROM AUTHOR]

Present study primarily focuses on interpreting the propagation pattern of Shear horizontal (SH) wave in a piezo-composite layered cylinder. The structure consists of three concentric cylinders composed of hollow fiber-reinforced (FR) cylinder enclosed within piezomagnetic (PM) cylinder along the curved surface area which is similarly superimposed by a piezoelectric (PE) cylinder. The overall system is believed to be pre-stressed in a circumferential direction. The common boundary between each of the cylinder is demonstrated as imperfectly bonded. At the interface of PM and PE media, mechanical, electrical, magnetic and inter-coupled types of imperfections are assumed. Dispersion relations have been obtained for both the electrically open magnetically short (EOMS) and electrically short magnetically open (ESMO) circuit condition. Dispersion curves have been plotted to unravel the peculiarities of parameters like the radius of the hollow cylinder, thickness of FR and PM cylinder, thickness ratio of PM and PE cylinder, initial stress parameters, helical angle of the reinforcement. The influence of different interface parameters on the phase velocity of the wave has been studied and marked distinctly. For a detailed study, two successive modes have been plotted. Present study may help in improving the performance of piezo-composite cylindrical surface acoustic wave (SAW) sensors. [ABSTRACT FROM AUTHOR]

On the basis of the analysis of thermoelastic motion, the current research develops a novel model of modified thermoelasticity. The rotating long hollow cylinders with fixed surfaces are considered in a generalized Moore–Gibson–Thompson thermoelastic model (MGTTE) framework, including the modified Ohm's law. The cylinders are made of a thermoelastic material that rotates at a uniform rotational speed and is elastic in the transverse direction. The set of equations for the MGT heat conduction in the new model is built under the influence of the electromagnetic field by including a delay time in the context of Green–Naghdi of the third kind (GN-III). The inner boundary of the hollow cylinder is not only restricted but also sensitive to heat loading. The outer surface, on the other hand, is also restricted but insulates the heat. The Laplace transform method is utilized to deal with the differential equations produced in the new domain and transfer the problem to the space domain. The Dubner and Abate method is used to compute dynamically and graphically depict the theoretical findings for an isotropic transverse material. After comparing the results of several thermoelastic theories, the implications for the electromagnetic field are discussed. [ABSTRACT FROM AUTHOR]

The problem of calculating the optimal annealing modes of functionally gradient bodies was formulated. An original method of its numerical solution based on the principle of stepwise parametric optimization is used. The finite element method was used to solve direct problems during the iterative construction of optimal heating-cooling for bodies of complex geometric shape and structure. The search for the optimal value of the control function does not require zero approximation and at each time step the function of one variable can be minimized. [ABSTRACT FROM AUTHOR]

Based on the generalized nonlocal thermoelastic theory and the memory-dependent differential (MMD) theory, the dynamic response of the inner surface of an infinite hollow cylinder under thermal shock is investigated. The heat transfer coefficient varies linearly with the temperature, the outer surface of the hollow cylinder is insulated, and there is traction-free on the inner and outer surfaces. The governing equation of the problem is established, and the Laplace transform is used to solve the governing equation, and the distribution law of physical quantity is expressed by the modified Bessel function. In the numerical calculation, the influence of non-local parameters is firstly studied. Second, the influence of different thermal conductivity on various physical quantities is studied. Finally, the effects of time delay factor and kernel function on physical quantities are studied. The results show that the non-local parameters have little effect on temperature, but have significant effect on displacement and stress. The change of thermal conductivity has obvious influence on temperature, displacement, and stress. The hysteresis factor affects the extremum of a physical quantity. [ABSTRACT FROM AUTHOR]

In this work, a hollow cylindrical optical microcavity is numerically investigated by finite-difference time-domain simulations. Enhancement of a single whispering-gallery mode (WGM) is realized by inserting a periodic hole array into the hollow cylindrical structure. Line of missing holes acts as an optical microcavity. Electric and magnetic field profiles of both typical and enhanced resonant modes are presented. Variations of the single-mode resonant frequency and its quality (Q) factor are studied as a function of structural parameters, which are hole radius, width of the missing hole line, and number of holes. This work shows that the hole radius and the width of the missing hole line strongly affect both the resonant frequency and Q factor while varying the number of holes does not influence the resonant frequency, but they monotonically change the Q factor. This work provides information for designing and optimizing an WGM optical microcavity.

In recent times, automotive manufacturing companies are focusing on developing components that is capable of increasing safety features associated with lightweight materials such as using aluminium. One such innovation is providing the vehicle with crash box, which is generally located at the front bumper. The function of the crash box is to safeguard the passenger by absorbing the kinetic energy of collision and self-deformation. In this paper, the authors presented a study of the compressive test applied on crash boxes with different types of honeycomb sandwich circular columns using 3D virtual modelling and finite element (FE) simulation with the help of Solidworks and Ansys Workbench respectively. This sandwich structure comprises two circular aluminium tubes filled with core shaped as a large-cell honeycomb lattice. Here, the crash boxes with three different honeycomb sandwich circular columns i.e., hexagonal, triangular, and semi-circular arrangement, were investigated and the energy absorption capabilities of these columns were studied. FE simulations were used to evaluate maximum stress that a material can sustain over a period under a load, material deformation, geometric changes, and load-displacement results using a constant material property of that of aluminium alloy, and the results of the three different arrangements were compared and it is known that the crash box with semi-circular arrangement has high energy absorbing capacity. [ABSTRACT FROM AUTHOR]

Experiments have been carried out on determining the value of the moment of inertia of a hollow cylinder. This study aims to analyze the value of the moment of inertia with variations in the radius of the hollow cylinder using the Phyphox Application (Physical Phone Experiment). This research is experimental. The tools and material used area 1-meter longboard, three hollow cylinders with different radius sizes but the same mass, smartphone, laptop, caliper, and balance.The experiment of rolling motion on a hollow cylinder on an inclined plane is assisted by data processing in a Phyphoxapplication. From the experiment, the result of the moment of inertia value from data processing is 4.89 x 10-4kg.m2, 9.82 x 10-4kg.m2, 12.4 x10-4kg.m2. This research can be used as a teacher reference in teaching the topic of moments of inertia in physics learning at school. This is highly recommended for distance learning during the pandemic so that mastery of concepts is maximized. Further research is suggested that it can be tried to use other materials with other types of rigid bodies to find the moment of inertia. Further references on digital application media to assist learning are also needed considering the dynamic development of technology.

• An experimental study on water entry of hollow cylinders is conducted. • Effect of fillet radius of the front on cavity dynamics at deep seal pinch-off is investigated. • Splash boundary of hemispherical-front cylinder remains vertical during cavity entrainment. • Different deep closure patterns for the three hollow cylinders are revealed. • The most extended internal jet is obtained with the flat-front hollow cylinder. In the present study, we investigate the water entry of three hollow cylinders with fronts of different fillet radii of 0, 5, and 10 mm. Particular attention is given to the effect of fillet radius of front on cavity dynamics. To interpret the mechanism of cavity evolution, a high-speed photography system is employed to capture instantaneous impact phenomena and behaviors of the hollow cylinders. Unique characteristics of the internal jet and ring-rupture pinch-off of the cavity are described and discussed. The results show that both dynamic patterns and characteristic parameters of the cavities differ with the fillet radius of the front. For the flat-front hollow cylinder, a fully developed streamlined gas cavity is formed, and the expansion rate and size of the cavity are substantially greater than those associated with slanted fronts. The cavity trajectory remains nearly vertical, and the internal jet is the most extended. With increasing fillet radius of the front, underdeveloped cavities with relatively small size are produced and the collapse time of the cavity is shortened. Furthermore, the cavity trajectory is characterized by lateral deflections, and the maximum attainable height of the internal jet is reduced. [ABSTRACT FROM AUTHOR]

• A novel mirror-assisted testing methodology is developed for 3D CSLDV measurement. • The virtual area of a structure behind the mirror is used for scan path design. • Virtual positions of laser heads behind the mirror are used for vibration stitch. • Panoramic 3D ODSs of a hollow cylinder are measured without moving the system. • MAC values between experimental and numerical results are larger than 0.98. A novel general-purpose three-dimensional (3D) continuously scanning laser Doppler vibrometer (CSLDV) system was recently developed by the authors to measure 3D vibration of a structure with a curved surface. As a non-contact system, it can avoid the mass-loading problem in 3D vibration measurement using triaxial accelerometers. In previous studies, the 3D CSLDV system was used to measure 3D full-field vibration of a turbine blade with a curved surface and identify its operating deflection shapes (ODSs) and mode shapes. The 3D CSLDV system had the same level of accuracy as that with a commercial 3D scanning laser Doppler vibrometer system, but can measure many more points in much less time than the latter. However, the 3D CSLDV system can be limited by its field of view, which is a common problem for optical-based measurement devices. Moving the 3D CSLDV system to different positions to measure different parts of a test structure is not practical during 3D CSLDV measurement, since the system has to be re-calibrated once it has been moved, which can be time-consuming and introduce measurement errors. This work proposes a novel mirror-assisted testing methodology for 3D CSLDV measurement that aims to measure vibration of difficult-to-access areas of a structure without moving the 3D CSLDV system during the test, and stitch ODSs of its different parts together to obtain its panoramic 3D ODSs. The proposed methodology includes a novel scan trajectory design method that uses virtual areas of the structure behind the mirror to conduct continuous and synchronous scanning of three laser spots, and a novel velocity transformation method that uses virtual positions of three laser heads behind the mirror to stitch ODSs of different parts of the structure together. To demonstrate the proposed methodology, 3D CSLDV measurement is conducted on an aluminum hollow cylinder specimen, which has difficult-to-access areas such as its side and back surfaces, with the assistance of the mirror to obtain its panoramic 3D ODSs corresponding to its first two modes. Comparison between identified ODSs of the hollow cylinder specimen from the experiment and mode shapes from its finite element model is made and modal assurance criterion values are larger than 0.98. [ABSTRACT FROM AUTHOR]

In the present work, we implement a graded finite element analysis to solve the axisymmetric 2D hyperbolic heat conduction equation in a finite hollow cylinder made of functionally graded materials using quadratic Lagrangian shape functions. The graded FE method is verified, and the simple rule of the mixture with power-law volume fraction is found to enhance the effective thermal properties’ gradation along the radial direction, including the thermal relaxation time. The effects of the Vernotte numbers and material distributions on temperature waves are investigated in depth, and the results are discussed for Fourier and non-Fourier heat conductions, and homogeneous and inhomogeneous material distributions. The homogeneous cylinder wall made of SUS304 shows faster temperature wave velocity in comparison to the ceramic-rich cylinder wall, which demonstrates the slowest one. Furthermore, the temperature profiles along the radial direction when n = 2 and n = 5 are almost the same in all Ve numbers, and by increasing the Ve numbers, the temperature waves move slower in all the material distributions. Finally, by tuning the material distribution which affects the thermal relaxation time, the desirable results for temperature distribution can be achieved.

The relations of a local gradient non-ferromagnetic electroelastic continuum are used to solve the problem of an axisymmetrical loaded hollow cylinder. Analytical solutions are obtained for tetragonal piezoelectric materials of point group 4 mm for two cases of external loads applied to the body surfaces. Namely, the hollow pressurized cylinder and a cylinder subjected to an electrical voltage V across its thickness are considered. The derived solutions demonstrate that the non-uniform electric load causes a mechanical deformation of piezoelectric body, and vice versa, the inhomogeneous radial pressure of the cylinder induces its polarization. Such a result is obtained due to coupling between the electromechanical fields and a local mass displacement being considered. In the local gradient theory, the local mass displacement is associated with the changes to a material's microstructure. The classical theory does not consider the effect of material microstructure on the behavior of solid bodies and is incapable of explaining the mentioned phenomena. It is also shown that the local gradient theory describes the size-dependent properties of piezoelectric nanocylinders. Analytical solutions to the formulated boundary-value problems can be used in conjunction with experimental data to estimate some higher-order material constants of the local gradient piezoelectricity. The obtained results may be useful for a wide range of appliances that utilize small-scale piezoelectric elements as constituting blocks. [ABSTRACT FROM AUTHOR]

In this work, a hollow cylindrical optical microcavity is numerically investigated by finite-difference time-domain simulations. Enhancement of a single whispering-gallery mode (WGM) is realized by inserting a periodic hole array into the hollow cylindrical structure. Line of missing holes acts as an optical microcavity. Electric and magnetic field profiles of both typical and enhanced resonant modes are presented. Variations of the single-mode resonant frequency and its quality (Q) factor are studied as a function of structural parameters, which are hole radius, width of the missing hole line, and number of holes. This work shows that the hole radius and the width of the missing hole line strongly affect both the resonant frequency and Q factor while varying the number of holes does not influence the resonant frequency, but they monotonically change the Q factor. This work provides information for designing and optimizing an WGM optical microcavity. [ABSTRACT FROM AUTHOR]

We propose new methods for the determination of the thermal stressed state of viscoelastic bodies made of functionally graded materials subjected to annealing. We develop a numerical algorithm for the solution of the corresponding problem and realize it for the problems of heat conduction and thermoviscoelasticity. The thermal stressed state of a hollow cylinder is determined according to the given conditions of annealing. The variations of its temperature and stressed state are illustrated. [ABSTRACT FROM AUTHOR]

The dynamic response of a hollow cylinder subjected to a hygrothermal coupled shock is studied. The memory-dependent differential is introduced into the heat transfer equation and the diffusion equation, and a memory-dependent differential generalized hygrothermal coupling model is developed. In this article, Laplace transform and inverse transform are used to find the closed-form solutions of various physical quantities. The influence of the hysteresis factor and the kernel function on the distribution of each physical quantity is analyzed and the time history of the hygrothermal coupling is studied. The numerical results show that the larger the ratio of temperature gradient hysteresis factor to heat flux hysteresis factor, the faster the wave speed. Also, the hysteresis factor affects the wave crest. For the time course of hygrothermal, it is once again verified that the hygrothermal wave has a finite propagation speed. At the same time, we can get the conclusion that the wave is dominated by fluctuations in the early stage after the onset of hygrothermal shock. The above findings are of reference value for the structural design and optimization of tubes in a hygrothermal environment. [ABSTRACT FROM AUTHOR]

Scattering rates arising from the interactions of electrons with bulk longitudinal optical (LO) phonon modes in a hollow cylinder are calculated as functions of the inner radius and the uniform axial applied magnetic field. Now, the specific nature of electron-phonon interactions mainly depends on the character of the energy spectrum of electrons. As is well known, in cylindrical quantum wires, the application of a parallel magnetic field lifts the double degeneracy of the non-zero azimuthal quantum number states; m ≠ 0 ; irrespective of all electron's radial quantum number l states. In fact, this Zeeman splitting is such that the m < 0 electron's energy subbands initially decrease with the increase of the parallel applied magnetic field. In a solid cylinder, the lowest-order; { l = 1 ; m = 0 } subband is always the ground state. In a hollow cylinder, however, as the axial applied magnetic field is increased, the electron's energy subbands take turns at becoming the ground state; following the sequence { m = 0 , - 1 , - 2... - N } of azimuthal quantum numbers. Furthermore, in a hollow cylinder, in general, the electron's energy separations between any two subbands are less than the LO phonon energy except for exceptionally high magnetic fields, and some highest-order quantum number states. In view of this, the discussion of the energy relaxation here is focused mainly on intrasubband scattering of electrons and only within the lowest-order { l = 1 ; m = 0 } electron's energy subband. The intrasubband scattering rates are found to be characterized by shallow minima in their variations with the inner radius, again, for a fixed outer radius. This feature is a consequence of a balance between two seemingly conflicting effects of the electron's confinement by the inner and outer walls of the hollow cylinder. First; increased confinement of the charge carriers generally leads to the enhancement of the rates. Second; the presence of a hole in a hollow cylinder leads to a significant suppression of the scattering rates. The intrasubband scattering rates also show a somewhat parabolic increase in their variations with the applied magnetic field; an increase which is more pronounced in a relatively thick hollow cylinder. [ABSTRACT FROM AUTHOR]

The two main research orientations on the problem of hydrogen embrittlement are examined: the study of fundamental principles and the disclosure of micromechanisms and the relation between hydrogen embrittlement and metal aging; the development of models and methods for predicting the kinetics of change in stress-strain state and for evaluating the longevity of structures subjected to hydrogen embrittlement. The state of the problem of hydrogen embrittlement of metals in the first direction is briefly analyzed. More attention is paid to the importance of predicting the behavior of charged metal structures under the influence of hydrogen embrittlement. We then examine the use of finite element modeling using the ANSYS software to compute the calculation analysis of a hollow cylinder subjected to internal and external pressures and hydrogen embrittlement. The cylinder material is nonlinear elastic and its properties depend on the hydrogen concentration at each point of the cylinder. Consideration is given to the influence of the rigidity of the stress state and the hydrogen concentration on the diffusion kinetics of hydrogen in the cylinder body. The problem is solved in time steps. The distributions of the hydrogen concentration and the stresses for a quarter of the volume of the cylinder are given, as well as the graphs of these values ​​according to the thickness of the wall of the cylinder at different times. It is shown that the ANSYS software package adapted to the resolution of such problems can model the behavior of different structures in a hydrogen-containing environment, taking into account the effects caused by both the influence of hydrogen on mechanical properties of the material and by the stress state of the structures, as well as by the influence of the stress state on the interaction kinetics of hydrogen with the structures.

In this article, the problem of time-dependent stress redistribution of a piezomagnetic rotating thick-walled cylinder under an axisymmetric hygro-thermo-magneto-electro-mechanical loading is analyzed analytically for the condition of plane strain. Using the constitutive equations, a differential equation is found in which there are creep strains. Primarily, eliminating creep strains, an analytical solution for the primitive electric and magnetic potential in addition to stresses is obtained. Then, creep strains are kept and creep stress rates are found by utilizing Norton’s law and Prandtl-Reuss equations for steady-state hygrothermal boundary condition. Lastly, the history of stresses and radial displacement as well as magnetic and potential fields during the time is obtained using an iterative method. In the numerical examples, the effect of angular velocity, hygrothermal loading and thermal and moisture concentration dependency of elastic constants is investigated comprehensively.

On the basis of the analysis of thermoelastic motion, the current research develops a novel model of modified thermoelasticity. The rotating long hollow cylinders with fixed surfaces are considered in a generalized Moore–Gibson–Thompson thermoelastic model (MGTTE) framework, including the modified Ohm’s law. The cylinders are made of a thermoelastic material that rotates at a uniform rotational speed and is elastic in the transverse direction. The set of equations for the MGT heat conduction in the new model is built under the influence of the electromagnetic field by including a delay time in the context of Green–Naghdi of the third kind (GN-III). The inner boundary of the hollow cylinder is not only restricted but also sensitive to heat loading. The outer surface, on the other hand, is also restricted but insulates the heat. The Laplace transform method is utilized to deal with the differential equations produced in the new domain and transfer the problem to the space domain. The Dubner and Abate method is used to compute dynamically and graphically depict the theoretical findings for an isotropic transverse material. After comparing the results of several thermoelastic theories, the implications for the electromagnetic field are discussed.

• The integrations in the Legendre polynomial approach is analytically solved to improve the computational efficiency. • The solutions according to the global matrix method are derived to verify the effectiveness of the presented approach. • Longitudinal mode attenuation curves rapidly decrease when torsional mode curves is approaching them. • The temperature amplitude of flexural torsional mode is not negligible, especially for a small radius-thickness ratio pipe. • Attenuation differences of various flexural orders are large at cut-off frequencies and mutation frequencies. A new solving procedure based on the Legendre polynomial series is developed to investigate the longitudinal guided waves in fractional order thermoelastic inhomogeneous hollow cylinders. Different from the available Legendre polynomial approach, integrals are calculated by the explicit and simple expressions to replace the numerical solutions. The solutions according to the global matrix method (GMM) are also derived for the first time to verify the effectiveness of the presented approach. Comparison of the CPU time indicates that the computational efficiency of the new solving procedure has a huge improvement. Then, the guided wave phase velocity dispersion curves, attenuation curves, displacement and temperature distributions for functionally graded hollow cylinders with different fractional orders, flexural orders, radius-thickness ratios and gradient fields are analyzed. It is found that the attenuation coefficients of flexural longitudinal modes rapidly decrease when the flexural torsional mode curve is close to the flexural longitudinal mode curve. Furthermore, notable influence of the flexural order on attenuation curves mainly occurs at the cut-off frequencies and mutation frequencies. In addition, a smaller radius-thickness ratio implies a larger attenuation, and the temperature amplitudes of flexural torsional mode are more and more close to those of longitudinal mode when the radius-thickness ratio decreases. [ABSTRACT FROM AUTHOR]

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In this study, thermal and mechanical stresses in hollow thick-walled functionally graded (FG) cylinders is presented under the convection boundary condition. The convective external condition and constant internal temperature in hollow cylinders are investigated. Inhomogeneous material properties produce irregular and two-point linear boundary value problems that are solved numerically by the pseudospectral Chebyshev method. The displacement and thermal stress distributions are examined for two different material couples under particular boundary conditions that are similar to their real engineering applications. Results have demonstrated that the pseudospectral Chebyshev method has low computation costs, high accuracy and ease of implementation and can be easily customized to such engineering problems. [ABSTRACT FROM AUTHOR]

The analytical and numerical analysis on the transient displacement and stress fields subjected to the electric load E z and E r in the electrostrictive hollow cylinder are studied in this paper. The electric and stress fields are uncoupled to derive the analytical solutions first. Then, the discussed displacement is decomposed into a quasi-static solution which satisfies inhomogeneous boundary conditions and a dynamic solution which satisfies homogeneous and initial conditions. After the quasi-static solution has been solved, the dynamic solution can be derived by using the methods of Hankel and Laplace transforms. Finally, the numerical examples are given to study the mechanism of dynamic stresses in case of different electric loads and structure sizes. It is concluded that the method and the process of the computing are simple, effective and accurate for the discussed problem and can easily be used in engineering design. [ABSTRACT FROM AUTHOR]

Solar water distillation is an effective technology for producing potable water using sustainable energy sources. However, the widespread use of this technology in industrial and domestic applications is hindered by low daily production compared to other methods. In this study, a new modification was introduced by placing a hollow cylinder inside a solar distiller and then integrating the cylindrical solar distiller with a solar heater (modified solar still). An economic analysis and study of the chemical and physical properties of the modified solar still (MSS) were carried out. The MSS produced a 296–300% increase in distillate water yield compared to a commercial solar still (CSS) on 17 July 2019, and reached 400% in other months depending on weather conditions. The costs of producing a liter of distilled water from the conventional and modified solar stills were 0.0282 and 0.0268 $/lit, respectively. Thus, the proposed solar distiller design is economically feasibile, reducing the cost of production compared to a conventional distiller and previous studies. The distillate water produced by the MSS and CSS has given the best results to all TDS, pH, and electrical conductivity tests according to local and international standards.

In any sensory system, the Electromagnetic (EM) shielding of the channel-carrying signal is a fundamental technique to provide a noise-immune measurement system. Severe failures and uncertainty may occur if the external EM fields interfered with the measurements. Typically, the shielding is realized by enclosing the channel-carrying signal with thinconductive hollow structures. However, with such structures, it is required to provide access to the interior components from the outside, for wires' connections, or better heat dissipation. This can be considered as a weakness in such the external magnetic fields can penetrate through the shielding structure. In this paper, the EM shielding effectiveness is considered for long hollow-cylinder structures with slots. The induced eddy current in thin-conductive shielding systems with slots together with the magnetic fields at different conditions are modeled. The objective is to determine the impact of the integrated slots along with the structure. The influence of the slots' sizes (𝛂) and position relative to the excitation magnetic field (i.e., the declination angle (𝛃)) are investigated to evaluate the shielding effectiveness by means of the determination of the shielding factor. The results reveal the inherent relationship between the shield parameters and shielding effectiveness. The shielding effectiveness deteriorates by the slots' integration within the shielding surface. However, decreasing the size of the slots improves the shielding, significantly, towards the shielding effectiveness of the continuous cylindrical structure. Additionally, utilizing the symmetry in the structure positioning the slots in the direction perpendicular to the magnetic field flux improves the shielding effectiveness, drastically. Such a model can be considered to evaluate the degree of effectiveness or success of integrating opening slots within the shielding structure, which can be applied to different types of instrumentation systems specifically at the sensor-electronics interface. [ABSTRACT FROM AUTHOR]