Isotropic Cylinder Research Articles

Experimental investigation and probabilistic analysis of the buckling load of isotropic cylinders under multiaxial loading

This paper presents a multitude of experimental results for cylindrical shells under combined loading. The loading is a combination of axial compression and bending moment. These are accompanied with numerical simulations. The load ratio itself is subject to scatter, a direct comparison and application of results for the sizing of shells is not straight forward. Therefore, a new approach is presented, which transfers the results to normalized load factors.

On an isotropic porous solid cylinder: the analytical solution and sensitivity analysis of the pressure

Within this work, we perform a sensitivity analysis to determine the influence of the material input parameters on the pressure in an isotropic porous solid cylinder. We provide a step-by-step guide to obtain the analytical solution for a porous isotropic elastic cylinder in terms of the pressure, stresses, and elastic displacement. We obtain the solution by performing a Laplace transform on the governing equations, which are those of Biot’s poroelasticity in cylindrical polar coordinates. We enforce radial boundary conditions and obtain the solution in the Laplace transformed domain before reverting back to the time domain. The sensitivity analysis is then carried out, considering only the derived pressure solution. This analysis finds that the time t, Biot’s modulus M, and Poisson’s ratio v have the highest influence on the pressure whereas the initial value of pressure P0 plays a very little role.

An Investigation into the Variables Influencing the Structural Bamboo Architecture Using Filled Concrete and Cement Mortar

Bamboo, as a green building material, plays a vital role in construction. Bamboo has good properties and appearance, making it highly attractive for building structures and designs. Since the compressive capacity of bamboo is considerably lower than its tensile capacity, with the ratio typically ranging between 300% to 900%, this limits its application dimensions in construction. Therefore, filling the original bamboo structural members with specific materials or applying different connection methods can not only maintain the appearance of the bamboo structure but also improve its compressive capacity and overall durability, thus expanding the application range of bamboo structural members and enhancing the performance of the architectural design process. Two hollow bamboo specimens were among the eight BFC specimens tested for this paper. Key components such as transverse stiffeners, steel bars, filler materials, and bamboo nodes were examined for their influence on the specimens’ ductility, peak strain, ultimate bearing capacity, and failure mechanisms. The test results showed that the ratio of the ultimate bearing capacity of BFC specimens to hollow bamboo samples could reach up to 538%, while the peak strain differences were minimal. A non-linear finite element model was developed and its accuracy confirmed based on the test results. This work proposes a new approach to determine the final axial compressive capacity of BFC columns by creating an elastic model of transversely isotropic cylinders. As a result, the primary goal of this study is to establish a foundation for more scientific building design techniques and procedures by examining the axial compression mechanics of structural bamboo filled with cement and concrete (BFC) and how it influences building design.

Thermomagnetic Transient Analysis of an Infinitely Long Transverse Isotropic Annular Cylinder Using the MGT Fractional Heat Conduction Model with a Non-Singular Kernel

Thermomagnetic Transient Analysis of an Infinitely Long Transverse Isotropic Annular Cylinder Using the MGT Fractional Heat Conduction Model with a Non-Singular Kernel

Construction of an inhomogeneous solution for the problem of torsion of a radially inhomogeneous transversal isotropic cylinder

Using the method of asymptotic integration of the equations of elasticity theory, inhomogeneous solutions are constructed for the problem of torsion of a radially inhomogeneous transversally isotropic cylinder of small thickness. It is considered that the elastic moduli are arbitrary continuous functions of a variable along the radius of the cylinder. An algorithm is given for constructing exact partial solutions of equilibrium equations for special types of loads, the lateral surface of the cylinder is loaded with forces that depend polynomially on the axial coordinate. Based on the solutions obtained, it is possible to evaluate the areas of applicability of applied theories for radially inhomogeneous cylindrical shells.

ON THE PROBLEM OF THE THEORY OF ELASTICITY FOR THE RADIALLY INHOMOGENEOUS TRANSVERSAL ISOTROPIC CYLINDER WITH A FIXED LATERAL SURFACE

Using the method of asymptotic integration of the equations of the theory of elasticity, the axisymmetric problem of the theory of elasticity for a radially inhomogeneous transversally isotropic cylinder of small thickness is studied. Suppose that the elastic moduli are arbitrary continuous functions of the radius of the cylinder. It is assumed that the side part of the cylinder is fixed, and stresses are set at the ends of the cylinder, leaving the cylinder in equilibrium. Solutions have been determined having the nature of a boundary layer and are localized at the ends of the cylinder. The first terms of its asymptotic expansion coincide with the Saint-Venant edge effect in the theory of plates. The nature of the stress-strain state has been studied. It is shown that some boundary layer solutions may not be extinguished by propagating far from the ends.

Thermocapillary motion of a solid cylinder near a liquid–gas interface: Janus geometry

In this work, an analytical model is developed for the thermocapillary propulsion of a solid cylinder near a convective liquid–gas interface. Thermocapillarity originates from the temperature-induced surface tension gradients at the liquid–gas interface when the surface temperature of a cylinder residing near the interface differs from the liquid phase. In this work, we consider Janus cylinders with piece-wise constant surface temperatures or heat fluxes. In the former case, we addressed the Gibbs' phenomenon induced by the points of discontinuity. The developed procedure allowed us to study the dynamics of the general case of cylinders with different surface ratios of piece-wise constant temperatures and find the configurations inducing the largest velocities. Most Janus configurations result in motion of the cylinder parallel to the liquid–gas interface. The efficiency of the propulsion parallel to the liquid–gas interface is of the same order of magnitude as the propulsion efficiency of an isotropic cylinder normal to the interface. Considering the emerging interest of scientific community in mechanisms beyond the catalytically induced propulsion, this study may help to shed light on new ways to modulate the propulsion.

Construction of homogeneous solutions of the torsion problem for a radially inhomogeneous transversely isotropic cylinder

The torsion problem for a radially inhomogeneous transversely isotropic cylinder of small thickness was investigated by the method of asymptotic integration of elasticity theory equations. It is assumed that the side part of the cylinder is stress-free, and boundary conditions are set at the ends of the cylinder, leaving the cylinder in equilibrium. The elastic moduli are thought to be arbitrary continuous functions of the variable along the cylinder radius. The formulated boundary value problem is reduced to a spectral problem containing a small parameter characterizing the thin-walledness of the cylinder. Homogeneous solutions are built, i.e. any solutions of the equilibrium equation satisfying the condition of no stresses on the side surfaces. It is shown that the solution of the torsion problem consists of a penetrating solution and a boundary layer character solution similar to Saint-Venant's edge effect in the theory of inhomogeneous plates. The penetrating solution determines the internal stress-strain state of a radially inhomogeneous cylinder. The stress state determined by the penetrating solution is equivalent to the torsional moments of stresses acting in the cross-section perpendicular to the cylinder axis. Solutions having the boundary layer character are localized at the ends of the cylinder and decrease exponentially with distance from the ends. These solutions are absent in applied shell theories. Asymptotic formulas for displacement and stresses are built, which make it possible to calculate the three-dimensional stress-strain state of a radially inhomogeneous transversely isotropic cylinder of small thickness. Based on the obtained asymptotic expansions, it is possible to assess the applicability of applied theories and build a refined applied theory for radially inhomogeneous cylindrical shells

Transient Response of Macroscopic Deformation of Magnetoactive Elastomeric Cylinders in Uniform Magnetic Fields.

Significant deformations of bodies made from compliant magnetoactive elastomers (MAE) in magnetic fields make these materials promising for applications in magnetically controlled actuators for soft robotics. Reported experimental research in this context was devoted to the behaviour in the quasi-static magnetic field, but the transient dynamics are of great practical importance. This paper presents an experimental study of the transient response of apparent longitudinal and transverse strains of a family of isotropic and anisotropic MAE cylinders with six different aspect ratios in time-varying uniform magnetic fields. The time dependence of the magnetic field has a trapezoidal form, where the rate of both legs is varied between 52 and 757 kA/(s·m) and the maximum magnetic field takes three values between 153 and 505 kA/m. It is proposed to introduce four characteristic times: two for the delay of the transient response during increasing and decreasing magnetic field, as well as two for rise and fall times. To facilitate the comparison between different magnetic field rates, these characteristic times are further normalized on the rise time of the magnetic field ramp. The dependence of the normalized characteristic times on the aspect ratio, the magnetic field slew rate, maximum magnetic field values, initial internal structure (isotropic versus anisotropic specimens) and weight fraction of the soft-magnetic filler are obtained and discussed in detail. The normalized magnetostrictive hysteresis loop is introduced, and used to explain why the normalized delay times vary with changing experimental parameters.

Analytic solution to isotropic axisymmetric cylinder under surface loadings problem through variational principle

Analytic solution to isotropic axisymmetric cylinder under surface loadings problem through variational principle

Using Thin Films of Phase-Change Material for Active Tuning of Terahertz Waves Scattering on Dielectric Cylinders.

The scattering of electromagnetic waves by isotropic dielectric cylinders can be dramatically modified by means of vanadium dioxide (VO2) thin-film coatings. Efficient dynamic control of scattering is achieved due to the variations in material parameters realizable by means of external biasing. In this paper, we study the scattering of terahertz waves in a case where the coating shells are made of VO2, a phase-change material, whose thin films may work rather as electromagnetic phase screens in the insulator material phase, but as lossy quasi-metallic components in the metallic material phase. The shells that uniformly cover the dielectric cylinders are investigated. Attention will be paid to the demonstration of the potential of VO2 in the external control of diverse scattering regimes of the dielectric-VO2 core-shell scatterer, while conductivity of VO2 corresponds to rather insignificant variations in temperature. In line with the purposes of this work, it is shown that the different resonant and nonresonant regimes have different sensitivity to the variations in VO2 conductivity. Both the total scattering cross section and field distributions inside and around the core are studied, as well as the angle-dependent scattering cross section.

Effect of temperature on adhesion behavior of layered piezoelectric structure

The effect of temperature on adhesion is neglected in classical adhesive contact theories. However, an increasing number of experimental results indicate that temperature has a prominent effect on adhesion behaviors. In this study, the anisothermal adhesive contact behaviors between two transversely isotropic piezoelectric cylinders with different initial temperatures is investigated by virtue of the generalized JKR model, where the contact interface is assumed to be perfectly bonded. The considered problem is reduced to coupled singular integral equations, which is derived by using the Fourier integral transform. The closed-form solutions of anisothermal generalized stress fields are obtained by taking the series expansion of the integrand induced by temperature difference. The effect of temperature difference on adhesion behaviors of two different types of layered piezoelectric structures under the action of mechanical-electro loadings is revealed. It is found that the pull-off force and contact size at pull-off moment decrease with increasing the temperature difference. The adhesion weakening effect induced by temperature difference diminishes when the electric loading is exerted. The results derived from this paper shed lights on understanding the adhesive contact behaviors of piezoelectric materials in the presence of temperature difference.

Vibrational analysis of transversely isotropic hollow cylinder based on fractional generalized thermoelastic diffusion models with nonlocal effects

Vibrational analysis of transversely isotropic hollow cylinder based on fractional generalized thermoelastic diffusion models with nonlocal effects

On the thermal stresses in chiral porous elastic beams

This paper is concerned with the strain gradient theory of porous thermoelastic solids. We study the deformation of isotropic chiral cylinders subjected to a temperature field that is linear in the axial coordinate. It is shown that the solution can be reduced to the study of two-dimensional problems. The results are used to investigate the deformation of a circular cylinder subjected to a uniform temperature variation. In contrast to the case of achiral materials, the thermal field in chiral cylinders produces torsional effects.

Generalized Thermoelastic Infinite Annular Cylinder under the Hyperbolic Two-Temperature Fractional-Order Strain Theory

This work introduces a new thermoelastic model of an isotropic and homogeneous annular cylinder. The cylinder’s bounding inner surface is shocked thermally, and the bounding outer surface has no temperature increment and volumetric strain. The governing equations in the context of the hyperbolic two-temperature generalized thermoelasticity with fractional-order strain theory have been derived. The numerical solutions of the conductive temperature, dynamic temperature, displacement, strain, and stress are illustrated in figures that use various values of fractional-order and two-temperature parameters to stand on their effects on the thermal and mechanical waves. The fractional-order parameter has significant impacts on the displacement, strain, and stress distributions. However, it does not affect dynamic or conductive temperatures. The hyperbolic two-temperature model is a successful model for making thermal and mechanical waves propagate at limited speeds.

Poroelastodynamic responses and elastic moduli of a transversely isotropic porous cylinder under forced deformation test

Existing transversely isotropic poroelastodynamics solutions are limited to infinite domains and without experimental validation. Furthermore, there is a lack of analytical simulations for the elastic moduli dispersion of fluid-saturated porous cylinders. To address these three limitations and investigate the mechanisms of moduli dispersion, we present the analytical solutions of the poromechanical responses and the elastic moduli dispersion of a transversely isotropic, fluid-saturated, finite porous cylinder subjected to a forced deformation test. Through an example, we demonstrate the effects of loading frequency, boundary conditions, and material’s anisotropy, dimension, and permeability on the responses of pore pressure, force, displacement, and dynamic elastic moduli of the cylinder. The specimen's responses are significantly influenced by the frequency of the applied load, resulting in a drained state at low frequencies and an undrained state at high frequencies. At high frequencies, the sample behaves identically for an open or a closed lateral boundary, and permeability has insignificant effects. The dynamic elastic moduli are mainly controlled by the loading frequency and the ratio of the sample’s radius to its height. Lastly, we show excellent matches between the newly derived analytical solution and laboratory measurements on one clay and two shale samples from Mont Terri.

Analytical simulation of the elastic moduli dispersion for an isotropic porous cylinder

There are extensive laboratory measurements of elastic moduli dispersion of porous materials, yet the mechanisms for the dispersion are not fully understood. Related analytical solutions are missing in the literature, potentially due to complex mathematical derivations. In this paper, we use Biot's theory of poroelastodynamics (PED) and present the first analytical solution for an isotropic fluid-saturated porous cylinder subject to a forced deformation test. This is done by introducing Helmholtz decomposition, two scalar potentials, and two vector potentials to decouple the original governing partial differential equations. The methods of matrix diagonalization and separation of variables are then used to solve the decoupled equations. The elastodynamics (ED) solution is also presented. We demonstrate the coupled responses of displacement, pore pressure, and stress and interpret systematically the mechanisms for the elastic moduli dispersion. Furthermore, we investigate comprehensively the effects of loading frequency, material's poromechanical characteristics, sample size, and boundary conditions on the elastic moduli dispersion. Finally, excellent matches are found between the analytical solution and published measurements of the dynamic Young's moduli and Poisson's ratios of a water-saturated clastic sediment rock and a glycerin-saturated limestone. The analytical solution captures the materials’ elastic moduli dispersion at both seismic and sonic frequencies. This work should be of interest to scientists and engineers who work on dynamics, vibration, and poromechanics.

Warping caused by surface elasticity in a nanowire under torsion

By combining molecular statics simulations and continuum mechanics-based modeling, we show in this paper that the torsion of a $\ensuremath{\langle}001\ensuremath{\rangle}$ single-crystal copper nanowire with a circular cross section gives rise to a warp, i.e., to a displacement field along the wire axis that renders the cross section nonplanar. This behavior, which is in apparent contradiction with what is predicted by continuum mechanics for an isotropic cylinder, can be well explained if we take into account the elastic response of the wire lateral surface. The latter is characterized by the anisotropy of the surface elastic constants and, more specifically in the case of torsion, by the surface shear constant ${C}_{44}^{S}$ whose strength as a function of the local orientation of the lateral surface is estimated independently from atomistic calculations on slabs presenting different vicinal surfaces. The solution of the torsion problem is then obtained by adopting a semi-inverse method in the framework of the finite strain theory in linear elasticity with Gurtin-Murdoch boundary conditions linking surface stress and bulk stress. It is shown that such an approach is well suited to explain quantitatively the warp obtained in our atomistic simulations and to prove the preponderant role played by the surface elastic constant ${C}_{44}^{S}$.

Theoretical Investigation of a Rotating Thermomagnetic Isotropic Transverse-Constrained Annular Cylinder with Generalized Ohm’s Law Using the Moore–Gibson–Thompson Model of Heat Transfer

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.

Exposure to acoustic waves on viscoelastic cylinder

The problem of the impact of acoustic waves in a homogeneous viscoelastic cylinder is considered. The investigation aims to investigate the diffraction of acoustic harmonic waves in a viscoelastic cylinder. The body is assumed to be in an infinite acoustic space filled with an ideal fluid. Numerical calculations of the angular and frequency characteristics of the scattered field for viscoelastic cylinders under the action of harmonic acoustic waves are carried out. In the case of steady waves, the Helmholtz equation describes the propagation of small disturbances in an acoustic medium. And in a viscoelastic homogeneous isotropic cylinder, scalar and vector Helmholtz equations with complex coefficients, the solution of which is described by Bessel and Neumann functions with complex arguments. A technique and algorithm have been developed for solving the problem of diffraction of acoustic harmonic waves in a viscoelastic cylinder. It has been established that the stress and displacement of a point of a viscoelastic cylinder take on a maximum value in the region of long waves. It was also found that considering the material’s viscous properties reduces the stress components to 10%.