Solid Circular Cylinder Research Articles

Branching of axial compression histories of solid cylinders undergoing thermo-chemo-mechanical changes

This work considers the uniaxial compressive creep of a solid elastomeric circular cylinder under a fixed dead load as it undergoes time dependent and temperature dependent changes in its macromolecular structure. The changes occur at temperatures exceeding 100 °C and consist of chemical scission of macromolecular network junctions and their re-crosslinking to form new networks in new reference configurations. The scission process causes softening due to modulus reduction and the re-crosslinking causes stiffening due to deformation of newly formed networks. A condition is developed for the time when the homogeneous uniaxial creep deformation history develops an non-homogenous barrel shaped branch. Branching times and the corresponding compression ratio are calculated from this condition using mechanical and chemical scission properties from the experimental literature.

Neutral inhomogeneity in circular cylinder subjected to prescribed boundary displacement

In this paper a single circular inhomogeneity embedded within a solid circular cylinder whose curved boundary surface is subjected to a given boundary displacement in axial direction is considered. The displacement neutrality of the coupled system of host body and inclusion is studied. The neutral inhomogeneity (inclusion) does not disturb the displacement, strain and stress fields in the host body. In this paper the deformation of the considered inhomogeneous cylinder is a linear antiplane shear deformation.

Wake characteristics of wall-mounted solid and foam-covered circular cylinders

The wake characteristics of wall-mounted finite submerged solid and foam-covered circular cylinders (height/diameter = 0.9) are explored using large-eddy simulation for a Reynolds number (based on the cylinder diameter) of 13 000, and the simulation results are validated using particle image velocimetry. The foam-covered cylinder consists of an inner cylinder wrapped with a highly porous open-cell foam and capped by circular plates at the top and bottom. Two recirculation regions are identified for both cylinders, based on time-averaged data, one downstream and another above the top surface of the cylinder. The presence of the foam induces changes in the characteristics of both recirculation regions. The foam covering also interrupts the formation of large periodic structures, the evidence of which can be seen in the temporal distribution and discrete Fourier analysis of the force coefficients and velocity fluctuations. The temporal lateral oscillations, represented by the coefficient of sway, are observed for the solid cylinder but are suppressed in the case of the foam-covered cylinder. Two dominating frequencies are consistently present for the solid cylinder, but no such frequencies can be identified for the foam-covered cylinder. Finally, spectral proper orthogonal decomposition modes are presented in order to further substantiate the findings.

Nonlinear mechanics of remodeling

In this paper, we present a large-deformation formulation of the mechanics of remodeling. Remodeling is anelasticity with an internal constraint—material evolutions that are mass and volume-preserving. In this special class of material evolutions, the explicit time dependence of the energy function is via one or more remodeling tensors that can be considered as internal variables of the theory. The governing equations of remodeling solids are derived using a two-potential approach and the Lagrange–d’Alembert principle. We consider both isotropic and anisotropic solids and derive their corresponding remodeling equations. We study a particular remodeling of fiber-reinforced solids in which the fiber orientation is time-dependent in the reference configuration—SO(3)-remodeling. We define an additional remodeling energy, which is motivated by the energy spent in collagen fiber-reinforced living systems to remodel to enhance stiffness or strength in the direction of loading. We consider the examples of a solid reinforced with either one or two families of reorienting fibers and derive their remodeling equations. This is a generalization of some of the proposed remodeling equations in the literature. We study three examples of material remodeling, namely finite extensions and torsion of solid circular cylinders, which are universal deformations for incompressible isotropic solids and certain anisotropic solids. We consider both displacement and force-control loadings. Detailed parametric studies are included for the effects of various material and loading parameters on fiber remodeling. It is observed that during remodeling, there is a competition between the action of the internal strain energy function and the remodeling energy. For a given material, a remodeling process dominated by strain energy works to align fibers in a direction that minimizes strain energy. On the other hand, a remodeling process dominated by the remodeling energy aligns fibers in the direction of the maximum principal strain according to a constitutive choice. We finally linearize the governing equations of the remodeling theory and derive those of linear remodeling mechanics.

Hygrothermal analysis of a semi-infinite cylinder: an integral transform approach

PurposeThe purpose of this paper is to examine the impact of moisture and temperature changes on the behavior of a semi-infinite solid cylinder made of T300/5208 composite material. This study aims to provide analytical solutions for temperature, moisture and thermal stress through the de-coupling technique and the method of integral transforms. Both coupled and uncoupled cases are considered.Design/methodology/approachThis study investigates the hygrothermo-elastic response of a semi-infinite solid circular cylinder using an integral transform technique that includes Hankel and Fourier transforms. The cylinder is subjected to prescribed sources, and a numerical algorithm is developed for the numerical computation of the results. The goal is to understand how the cylinder responds to changes in temperature and moisture.FindingsThe paper presents an analytical solution for temperature, moisture and thermal stress in a semi-infinite solid cylinder obtained through the use of an integral transform technique. The study focuses on a graphite fiber-reinforced epoxy matrix composite material (T300/5208) and discusses the coupled and uncoupled effects of temperature, moisture and thermal stress on the material. The results of the transient response hygrothermo-elastic field are presented graphically to provide a visual representation of the findings.Research limitations/implicationsThe research presented in this article is primarily hypothetical and focused on the analysis of mathematical models.Originality/valueTo the authors' best knowledge, this study is the first to investigate the hygrothermal effect in a semi-infinite circular cylinder. Additionally, the material properties used in the analysis are both homogenous and isotropic and independent of both temperature and moisture. These unique aspects of the study make it a novel contribution to the field.

Localized necking and bulging of finitely deformed residually stressed solid cylinder

In this paper, we investigate the influence of residual stress on the stability of a solid circular cylinder subject to axial extension. The nonlinear theory of elasticity is used to derive the equations governing the linearized incremental deformations superimposed on a known finitely deformed configuration. Specialized to the neo-Hookean model with residual stress, the bifurcation analysis results in an exact bifurcation condition for zero and periodic modes, based on the Stroh formalism. An expansion technique is adopted to treat singularities in the governing equations. We investigate three loading scenarios, specifically, gradual increase in axial stretch with constant residual stress and gradual increase in residual stress with fixed axial length or fixed axial force. In each case, the zero mode, corresponding to a localized bifurcation, occurs first. An explicit bifurcation condition for the zero mode is derived, which accounts for the effect of geometric dimensions, the residual stress, and the axial elongation on the stability of the solid cylinder. The critical values of the residual stress and the axial force for localized necking or bulging to occur are identified. In particular, we show that a reduction in residual stress delays the onset of localized necking. At constant values of pre-stretch, with 1 . 5 < λ < 2 . 10692 , localized necking occurs at a critical residual stress, whereas localized bulging occurs when λ > 2 . 10692 . We use the Maxwell equal-area rule to characterize the “two-phase” deformation consisting of necked and bulged regions. It is shown that the Maxwell values of stretch identify the radii of the two regions, which are connected by a transition zone that translates along the cylinder. At the completion of “two-phase” deformation, the stretch is again uniform.

Saint-venant Torsion of Functional Graded Orthotropic Piezoelectric Hollow Circular Cylinder

This paper gives an analytical solution to the Saint-Venant torsion of the hollow and solid circular cylinder made of orthotropic functionally graded piezoelectric material. The elastic flexibility coefficients and piezoelectric constants and permittivities have only radial dependence. The considered material non-homogeneity is described by power function. The solution of the Saint-Venant torsion problem is presented for Prandtl’s stress function, shearing stresses, electric displacement potential function, torsion function and electric potential function. An example illustrates the application of the formulated analytical method.

Finite extension of accreting nonlinear elastic solid circular cylinders

Finite extension of accreting nonlinear elastic solid circular cylinders

INFLUENCE OF NON-ISOTROPIC DIFFUSION ON EFFECTIVE REACTION RATES IN CATALYST PARTICLES

The non-isotropic diffusion and reaction problem in cylindrical particles of different cross-sections is analyzed in this contribution employing the one-dimensional Generalized Cylinder Model (1D-GCG). Such a model presents a single parameter of straightforward calculation from the geometrical magnitudes of the catalyst particles. Different but uniform values of axial and transversal effective diffusivities are assumed. The performance of the 1D-GCG model for the effectiveness factor estimation is assessed for a variety of particle shapes and a set of kinetic expressions. Maximum errors in the predictions, varying a Thiele modulus and the axial-to-transversal diffusivities ratio, are below 6% for the first order reaction and rise up to around of 9% and 11% for a LHHW (Langmuir-Hinshelwood-Hougen-Watson) expression at the verge of the appearance of multiple steady states, in the case of Raschig rings and solid circular cylinders, respectively.

CFD analysis of turbulent forced convection over a spinning cylinder in an enclosed channel

• More practical scenario of speed ratio has been used in this study • Blockage ratio affects both the flow and thermal fields • Rotational velocity and direction do not affect the flow or thermal field • Bulk flow Reynolds number influences both thermal and flow fields • Pressure drag dominates over viscous drag at higher Reynolds number A CFD approach has been used to analyze fully developed turbulent flow and heat transport over a spinning hot circular solid cylinder inside an enclosed channel. The finite element approach is used to solve the Reynolds-Averaged Navier-Stokes and energy equations and the shear stress transport model. The flow is explored for various Reynolds numbers ranging from 3 × 10 3 to 10 7 with the blockage ratios of 0.05, 0.1, and 0.15 along with the variation of speed ratios of the rotating cylinder. This study found that the direction and speed of the cylinder have an insignificant effect on thermo-fluid characteristics. On the other hand, the drag coefficient decreases while the average Nusselt number increases to a specific value of Reynolds number and then becomes almost constant. Effectiveness increases for a lower Reynolds number and then becomes stable. The heat performance of the rotating cylinder for the stationary one and the contributions of pressure drag are presented here.

Branching during axial compression histories of solid cylinders of time-dependent materials

This work considers the uniaxial compression of a solid circular cylinder of time-dependent material. Initially, the cylinder undergoes a homogeneous compression history. The purpose is to determine a time when this deformation history can form a new inhomogenous branch. Material time dependence is described by a nonlinear single-integral constitutive equation that relates the stress in the material to its deformation history. A criterion is developed for determining branching times using a Pipkin–Rogers constitutive equation for nonlinear incompressible isotropic viscoelastic solids. For the purpose of numerical examples, material parameters are chosen so that the material acts as a neo-Hookean material in its short-time response and a softer one in its long-time equilibrium response. Examples show that characteristic relaxation times and deformation histories influence the time to branch and the corresponding compressive stretch and compressive force.

Effect of porous media on wake-induced vibration (WIV) in tandem circular cylinder

In practical engineering, cylindrical structures are frequently arranged in tandem under different flow environments. In this study, wake-induced vibration (WIV) of a solid circular cylinder in the wake of a stationary porous cylinder is numerically investigated. A numerical model including the porous medium and vibration modules is established by using the Immersed Boundary (IB) method and the calculation accuracy of the model is verified by the experiment. Seven porosities of the upstream cylinder from 0.0 to 1.0 are considered and the downstream cylinder is allowed to oscillate in both streamwise and transverse directions. The effects of the gap between the two cylinders, the Reynolds number (Re) and the reduced velocity (Ur) on the upstream-stationary-downstream-vibrating tandem cylinders are investigated in terms of shear layer reattachment, vortex impingement and wake interference. The wake flow pattern and the vortex shed from the porous cylinder are vulnerable to the porosity of the cylinder. As a result, the vibration of the downstream cylinder caused by the wake changes at different porosities. Besides, the hydrodynamic force and vibration frequency are also tightly associated with the wake interaction. At different reduced velocities (Ur) and Reynolds numbers (Re), the WIV and the force on the cylinder change significantly.

Influence of active flow modulation on conjugate mixed convection inside a vented cavity

The current work is an attempt to examine the performance of mixed convection heat transfer within a vented square cavity with dynamic flow modulation via a rotating heat conducting circular cylinder. External cold air is forcibly imposed through an inlet opening located at the bottom of the left wall of the cavity, while an exit port is placed at the top of the right wall. Isoflux heating is applied on the right wall, while the remaining solid wall boundaries are assumed insulated. A solid circular cylinder serving as dynamic flow modulator and rotating in counter-clockwise direction is placed near the bottom portion of the right heated wall. The governing mass, momentum, and energy equations representing the mathematical model of the present problem are solved in non-dimensional form using Galerkin finite element method. Parametric simulation is performed for wide range of governing parameters (Reynolds, Grashof, and Richardson numbers) within mixed convection regime under different dynamic conditions of the rotating cylinder characterized by the ratio of cylinder peripheral speed to mean inflow air velocity. Effects of the above governing parameters are analyzed through the visualization of streamline and isotherm plots, and the distribution of average and normalized Nusselt numbers of the heated wall, average fluid temperature in the cavity and the variation of pumping work required. Findings of the present study reveal that maximum heat transfer can be obtained by simultaneous increase of Reynolds and Grashof numbers, while careful selection of speed ratio of the rotating cylinder is necessary to obtain the optimum results within mixed convection regime. About 5.3% higher heat transfer enhancement is observed at highest speed ratio and higher Reynolds and Grashof numbers compared to the same for having stationary cylinder.

Polynomial mode approximations for longitudinal wave dispersion in solid and hollow circular cylinders

The characteristic equation for wave dispersion in solid or hollow circular cylinders is a transcendental equation: no closed-form solution exists and it can only be solved numerically. The characteristic equation for a hollow circular cylinder is substantially longer and more complex to solve than the equation for a solid cylinder. This paper examines, at different orders of approximation, two polynomial approximations (Jacobi mode approximation and an approximation by Widehammar, Gradin and Lundberg) which simplify the computation of dispersion curves. We focus on the approximation error for the first four modes of axially symmetric longitudinal waves, for both solid and hollow circular cylinders. The two polynomial approximations yield accurate dispersion curves for a solid cylinder, provided a sufficient order is used. For a hollow circular cylinder, the numerical limits of thinner cylinders prevent the use of the highest orders of approximation, limiting the accuracy of the dispersion curves. Classic theories for thin and thick cylindrical shells (by Naghdi and Cooper, and Herrmann and Mirsky), remain useful alternatives when computing dispersion curves for the first propagation mode for very thin hollow circular cylinders. We find that Widehammar’s approximation yields more accurate dispersion curves than Jacobi mode approximation for hollow cylinders, for a given order of approximation, as well as being more straightforward to program.

Torsional instability of incompressible hyperelastic rubber-like solid circular cylinders with limiting chain extensibility

In this paper we demonstrate the application of a newly proposed generalised neo-Hookean strain energy function within the family of limiting chain extensibility models to an instability problem in the torsion of incompressible isotropic rubber-like stretched solid circular cylinders. The instability of concern arises for sufficiently large twists where a kink or knot suddenly appears. An energy approach to investigation of this instability was given by Gent and Hua (2004) for a neo-Hookean elastic material, together with experimental observations on vulcanised rubber rods. We employ their framework in the present work on using the new limiting chain extensibility model. The model parameters are first obtained by fitting with experimental data for vulcanised rubber due to Gent and Hua. Then we use the instability criterion of Gent and Hua to calculate the critical twist at the onset of a knot formation with the new model. It is shown that the model provides more accurate predictions of the critical twisting angle at which the kink instability is initiated in vulcanised rubber compared with the neo-Hookean model used by Gent and Hua (2004). An alternative approach for slender thin rods proposed by Murphy (2015) is also implemented for the new model, and is shown to be a more tractable alternative method for limiting chain extensibility models.

Extension and torsion of rubber-like hollow and solid circular cylinders for incompressible isotropic hyperelastic materials with limiting chain extensibility

In this paper we demonstrate the application of a newly proposed generalised neo-Hookean strain energy function within the family of limiting chain extensibility models to the problem of extension and torsion in incompressible isotropic rubber-like tubes and solid circular cylinders. We consider a general deformation involving extension and torsion in tubes, and subsequently specialise to the simple torsion of solid cylinders. Expressions for the twisting moment M, axial load N and the inflation pressure P (for tubes) are derived and presented for all the considered deformations. Using the proposed model, solutions are obtained for the critical axial stretch λcz beyond which the specimens exhibit the reversal of the Poynting-type effect upon twisting for both stretched tubes and solid cylinders. Furthermore, it will be demonstrated that the response function of the model is compatible with Penn and Kearsley's scaling law in torsion and can be directly derived from the ensuing experimental data. While the problem of torsion in elastic tubes and cylinders has been well-studied, this work provides a contribution to nuanced aspects of this problem including the prediction of the critical axial stretch λcz at which Poynting-type effects reverse in stretched specimens and the demonstration of compatibility with the scaling law of Penn and Kearsley.

Experimental assessment of mass transfer characteristics of polypropylene surfaces for low flow falling film liquid desiccant air- conditioning applications

Corrosion problem of metallic surfaces has resulted in a bottleneck situation deterring widespread acceptability of liquid desiccant air conditioning systems. In the current experimental study, mass transfer analysis of non-corrosive polypropylene plastic surfaces, Plain and Modified solid circular cylinders, are investigated on an adiabatic vertical falling film tower. The performance of the vertical solid PP circular cylinder surfaces is compared with PP plate surface to deduct suitable surface for the development of low flow liquid desiccant air conditioning systems. It is found that under the tested conditions, the mass transfer coefficient of the Plain PP circular cylinder is 1.65 times superior to Plain PP plate. The optimal mass transfer coefficient of ∼20 g/m2s for the Plain PP circular cylinder is obtained at ∼1.5 ratio of the mass flow rate of liquid to air, whereas the mass transfer coefficient of the Modified PP circular cylinder continuously increases for the studied range of the mass flow rate of liquid to air ratio. Furthermore, a new generalized correlation for Sherwood number is proposed to predict the performance of different types of falling film towers (plastic/metallic) under adiabatic/non-adiabatic operating conditions by incorporating dynamic flow characteristics, driving thermal and mass transfer potential and wetness characteristic factor.The mean effective error of the current correlation against nine experimental datasets is 16.6%.

The effect of fiber-matrix interaction on the kinking instability arising in the torsion of stretched fibrous biofilaments

The response of fibrous soft tissues undergoing torsional deformations is a topic of current interest. Such deformations are common in ligaments and tendons and are also of particular interest in cardiac mechanics. The problem of torsion superimposed on extension of incompressible hyperelastic solid circular cylinders is a classic problem of nonlinear elasticity that has been considered by many authors in the context of rubber elasticity particularly for isotropic materials. A striking feature of such problems is the instability that arises with sufficiently large twist where a kink and then a knot suddenly appears. An energy approach to examining this instability when the extension and twist are prescribed was described by Gent and Hua (2004) and illustrated there for a neo-Hookean isotropic elastic material. The theoretical results were compared with experimental observations on natural rubber rods. Murphy (2015) has shown that the approach of Gent and Hua (2004) for isotropic materials can be simplified when the rods are assumed to be thin and this theory was applied to transversely isotropic materials by Horgan and Murphy (2016). In contrast with the case for isotropic materials, it was shown there that the kinking instability occurs even in the absence of stretch, i.e., for the case of pure torsion. Here we are concerned with the implications of this simplified thin rod instability theory for fiber-reinforced transversely isotropic materials that reflect fiber-matrix interaction. It is again shown that the kinking instability occurs even in the absence of stretch, i.e., for the case of pure torsion. The results are illustrated for a specific strain-energy density function that models fiber-matrix interaction. It is shown that the critical twist at which kinking occurs decreases as a measure of fiber-matrix interaction is increased so that the fiber-matrix interaction has a destabilizing effect. The results are illustrated using experimental data of other authors for skeletal muscles and for porcine brain white matter tissue.

Thermoelastic diffusion of a solid cylinder in the context of modified Green–Naghdi models

The generalized thermoelastic diffusion model is introduced and applied to an isotropic cylinder. The cylinder is under the effect of thermal flux and chemical potential. Some modifications are made to the Green and Naghdi model. Creative multi-phase-lag models with and without energy dissipation are proposed to discuss the thermoelastic diffusion of the circular solid cylinders. The analytical solutions of thermoelastic diffusion governing equations of the solid cylinders have been deduced. Comparing examples are presented between the simple and refined Green–Naghdi of types II and III models. The validity of results is worthy and benchmark outcomes are accounted for to help different specialists in their future examinations.

Suitability of plate versus cylinder surface for the development of low flow falling film liquid desiccant dehumidifiers

Liquid desiccant systems (LDS) are promising as they can be driven by renewable energy. Presently, plastic falling film towers are gaining more attention than metallic columns in LDS due to their excellent anti-corrosive characteristics. However, plastics suffer from penurious performance due to their hydrophobic nature. Apart from solid surface wettability, its geometry also plays a vital role in the formation of the continuous thin film over it. In the current experimental work, the dehumidification performance of adiabatic vertical polypropylene (PP) solid circular cylinders is investigated as an alternative to vertical PP plates. Modified circular cylinder surface is prepared following surface modification to overcome hydrophobic nature of the plastic surface. The performance of the circular cylinder surface is compared with the plate surface. It was found that the Plain PP circular cylinder offered 21–200% improvement in dehumidification rate as compared to the Plain PP plate with an average improvement of 55.9%. Similarly, the Modified PP circular cylinder enhanced the dehumidification rate of the Plain PP circular cylinder by 18.2–61% with an average improvement of 31.3%. A new generalized correlation is proposed to predict the effectiveness of adiabatic and non-adiabatic falling film towers by incorporating shear force, enthalpy difference, and moisture transfer potential between liquid desiccant and air along with wetness behavior parameters. The mean effective error of the current correlation is 11.7% for eight datasets. The findings of this study could be useful for designing small capacity low flow falling film tower-based solar hybrid liquid desiccant systems for residential and commercial applications.