Cylinder Shell Research Articles

Thickness evaluation of hollow nonmagnetic cylinders utilizing a motional eddy current

This paper presents a way to calculate the shell thickness of nonmagnetic hollow cylinders for nondestructive applications. Aluminum cylinders with a solid structure and with a hollow structure are considered. The motion component of the induced eddy currents in a conductive cylinder is utilized to evaluate the shell thickness of hollow conductive cylinders at various frequencies and at variable speeds. One axisymmetric excitation coil and two axisymmetric pickup coils with antiserial connection are used. An analytical method using an axisymmetric computational model is developed for a parametric analysis of solid and hollow cylinder structures and shell thickness calculations, in which Fourier series are utilized. A 2D axisymmetric finite element method is also performed for a comparison with the results of the analytical method. The measurements at variable speeds and at various frequencies are presented with various hollow aluminum cylinders. The high linearity of the induced voltage versus the speed curve makes it possible to calculate the shell thickness of nonmagnetic hollow cylinders at different speeds.

Seismic rehabilitation of gravity load-designed interior RC beam-column joints using ECC-infilled steel cylinder shell

A practical method was experimentally investigated to rehabilitate damaged gravity load-designed interior reinforced concrete beam-column joints featured with no transverse reinforcement. The method applied engineered cementitious composite (ECC) to fill a steel cylinder shell to encase the joint zone. Test program consisted of three as-built and two rehabilitated half-scale interior beam-column joint subassemblies subjected to cyclic loading with increasing amplitudes. The as-built specimens were first tested to shear failure of the joints and two of them were then rehabilitated in the joint zone using two cylinder shells of different dimensions for retesting. Test results found that the failure mode shifted from shear failure of the joints in the as-built specimens to flexural failure at the beam ends in the rehabilitated specimens. Peak values of column shear and corresponding deformability averaged an increase of about 32% and 60%, respectively. The beam-column joint using the cylinder shell of large dimension had a slightly better rehabilitation effect than that of small dimension. In addition, parametric studies were performed by means of the finite element method (FEM) based simulation. Numerical results indicated that appropriate thickness of the enlarged body of the cylinder shell ranged from 3 to 5 mm, and the proper length of the connection segment varied from 50 to 100 mm.

Collapse of the spatial double-layer cylinder shell by experimental study

Large span spatial steel structures, such as gymnasiums, exhibition halls, airport terminals, or railway hubs, have developed rapidly over the last four decades. However, the mechanical properties of these structures under complex loads, particularly their seismic performance under severe earthquakes, are not sufficiently understood. During the 2013 M7.0 Lushan earthquake in China, some of the large span spatial structures suffered damage of varying degrees, which necessitates a review of previous seismic designs and theories. This paper investigates the characteristics and rules of the seismic damage of large span spatial structure during the Lushan earthquake and discusses the possible causes of such damage. A shaking table test was conducted with a down-scaled model of a double-layer cylindrical shell structure to obtain the dynamic response of a structure by reasonably arranging the acceleration, velocity and displacement measuring points. The failure pattern and progressive collapse process of the structure under a severe earthquake were investigated. The buckling of members increased with the increment of ground motion, although this effect was not considered in the present code for seismic design for double-layer shell spatial structures. The seismic damage in the test was mainly represented by overall buckling of the upper chord, web member and lower chord, which is the direct reason for the structural collapse during a severe earthquake. The test results indicated that the change in surface curvature of the structure resulting from deformation during a severe earthquake transformed gravitational potential energy into kinetic energy and caused chord members to impact and fracture, thereby inducing progressive collapse of the structure. The findings of this paper provide a basis for the seismic theory and design of large span spatial steel structures. The buckling effect of double-layer cylindrical shell structures, the dynamic amplification effect of the support structures, and the transformation of gravitational potential energy to kinetic energy in particular would be of interest to researchers and designers.

Research on Influencing Factors of Magnetic Shielding Effectiveness of Finite Length Cylinder

The article mainly studies the shielding effectiveness (SE) inside a cylinder with a finite-length metal shell. Since the SE inside an infinite-length cylinder is equal everywhere, this article focuses on exploring the SE of a finite-length metal shell cylinder. The article simulates the influence of the cylindrical shape factor (the ratio of the height to the inner diameter of the cylinder) on the SE at different frequencies; the influence of the frequency of the external magnetic field on the SE of the cylinder; the change of the SE on the central axis of the cylinder; the change in the SE on the central axis of the cylinder when a small hole is opened at the centre of the bottom of the cylinder; the change in the SE on the central axis of the cylinder when small holes are opened at the centre of the upper and lower surfaces of the cylinder.

Buckling of composite cylindrical shells with ovality and thickness variation subjected to hydrostatic pressure

The initial geometric imperfection is one of the primary factors affecting the buckling behaviors of composite cylindrical shells under hydrostatic pressure. In this study, ovality and thickness variations as two representative types of the geometric imperfections are considered. After measuring the geometric imperfections, a typical carbon fiber reinforced polymers (CFRP) cylindrical shell is tested to obtain the buckling pressure. The buckling behaviors of the shell sample are analyzed in combination with the strain responses. By using the nonlinear numerical analysis, the buckling shapes of the CFRP cylinder shells with different combinations of ovality and thickness variation are firstly discussed. The rules of influence of such imperfections on the buckling pressure are then obtained by nonlinear regression method. Finally, an empirical formula is proposed to predict the buckling pressure of the composite cylinder shells, and the calculated results from the formula are in good agreement with the numerical results.

Mechanical performance and defect analysis of the imperfect micro smooth gyroid cylinder shell structure

Projection micro-stereolithography (PμSL) technique has been demonstrated effective in fabricating the micro lattices. However, the complex fabrication process would inevitably yield stochastic geometric defects within the target structure. In this paper, compressive mechanical properties and deformation modes of the micro gyroid cylinder shell structure with defects originated from the PμSL process were examined through experimental test and numerical simulation. Both the synchrotron X-ray tomography (SR-μCT) investigation and interrupted in-situ compression experiment were conducted to study the role of process-induced defects on the mechanical behavior. Testing results indicated that the fabricated thickness value was much larger than the design value, which had a non-negligible effect on the mechanical properties of the gyroid cylinder shell structure. Then, the reconstructed 3D true model was proposed based on the 2D tomography images. Simulation results indicated that the true model predicted results were more consistent with the experimental results when compared with the ideal model.

Nonlinear Mixed Convective Flow over a Moving Yawed Cylinder Driven by Buoyancy

The fluid flow over a yawed cylinder is useful in understanding practical significance for undersea applications, for example, managing transference and/or separation of the boundary layer above submerged blocks and in suppressing recirculating bubbles. The present analysis examines nonlinear mixed convection flow past a moving yawed cylinder with diffusion of liquid hydrogen. The coupled nonlinear control relations and the border restrictions pertinent to the present flow problem are nondimensionalized by using nonsimilar reduction. Further, implicit finite difference schemes and Quasilinearization methods are employed to solve the nondimensional governing equations. Impact of several nondimensional parameters of the analysis on the dimensionless velocity, temperature and species concentration patterns and also on Nusselt number, Sherwood number and friction parameter defined at the cylinder shell is analyzed through numerical results presented in various graphs. Velocity profiles can be enhanced, and the coefficients of friction at the surface can be reduced, for increasing values of velocity ratio parameters along chordwise as well as spanwise directions. Species concentration profile is reduced, while the Sherwood number is enhanced, for growth of the Schmidt number and yaw angles. Furthermore, for an increasing value of yaw angle, skin-friction coefficient in chordwise direction diminishes in opposing buoyancy flow case, whereas the results exhibit the opposite trend in assisting buoyancy flow case. Moreover, very importantly, for increasing magnitude of nonlinear convection characteristic, the liquid velocity and surface friction enhance in spanwise direction. Further, for increasing magnitude of combined convection characteristics, velocity profiles and coefficient of friction at the surface enhance in both spanwise and chordwise directions. Moreover, we have observed that there is no deviation for zero yaw angle in Nusselt number and Sherwood number.

Multilayer toroidal tuned liquid column dampers for seismic vibration control of structures

The toroidal tuned liquid column damper (TTLCD) is a recently developed device, which extends the application scenarios of liquid column dampers to multidirectional vibration control. Based on the single-TTLCD, this article creatively designs a multilayer-TTLCD, composed of several cylinder shells and baffles, to improve the damping performance in multidirection. The real-time hybrid simulation (RTHS) technique is employed to experimentally investigate the control efficiency of the multilayer-TTLCD. It is confirmed that the multilayer configuration makes it possible to incorporate more oscillating liquid into the columns of the container without extra occupied floor area, and thus the liquid mass can be raised. Due to the increase of the liquid mass, the multilayer-TTLCD shows certain improvements on peak and root-mean-square (RMS) displacement mitigation over the single-TTLCD when suppressing one specific structural vibration mode. More importantly, it is found that the multilayer-TTLCD is beneficial in multimodal vibration damping and has potential to control multi-order modal responses of structures simultaneously with a wide frequency range.

In-situ synchrotron X-ray tomography investigation of the imperfect smooth-shell cylinder structure

Lattice materials at micro scale with extraordinary stiffness and strength have demonstrated promising industrial application potentials in aerospace, transport, automotive, biomedical and other sections. However, the complex fabrication process at micro scale will inevitably induce stochastic geometric defects within as-fabricated lattice materials, thus quantitatively evaluation of the mechanical integrity of 3D-printed micro lattice structures becomes a critical important issue. In this paper, mechanical behavior of the micro Schwarz Primitive triply periodic minimal surfaces (P-TPMS) cylinder shell structures fabricated with projection micro-stereolithography (PμSL) 3D printing technique were investigated. Meanwhile, synchrotron X-Ray micro-tomography (SR-μCT) 3D imaging and interrupted in-situ compression experiment were employed for quantifying the effect of defects on the compression mechanical performances. It is found that the thickness along vertical direction was larger than along horizontal direction. Afterwards, three different types of finite element models were developed for understanding the effects of fabrication defects on the mechanical behavior characteristic. Simulation results demonstrated that the statistical model was more accurate and efficient when compared with the ideal model and real geometry reconstructed model. Finally, parametric study was also presented to gain insight into the role of thickness imperfections on the mechanical performance of the shell.

An improved adaptive web sampling method for node deviation inspection of single-layer latticed shells

The node positions of single-layer latticed shells in service usually deviate from their design positions, and a few nodes of the shell may exist larger positional deviations than other nodes, which could result in a progressive collapse or overall buckling of the shell. To avoid the significant loss of structure failure, these nodes with large positional deviations should be considered in the structural inspection sampling. However, existing sampling methods in the structural inspection are designed for independent products that ignore the dependence in these nodes and are unsuitable for node positional deviation inspection of single-layer latticed shells. To solve this problem, the node positional deviation aggregation is defined and calculated based on the theory of spatial local autocorrelation, and an improved adaptive web sampling (IAWS) method is proposed in this paper, which consists of three parts: calculation of node connection matrix, adaptive web sampling, and supplementary sampling. Specially, the supplementary sampling is proposed to improve the overall sampling accuracy for adaptive web sampling, and the selection of supplementary samples is based on the relationship between the sample position and the total node deviation reckoning error derived in this paper. Besides, two performance indicators are adopted to evaluate the overall reckoning accuracy of sample methods, and two new performance indicators are proposed to assess the deviation aggregation area sampling accuracy. The numerical analysis results of two Kiewitt shells and a cylinder shell show that IAWS can provide a higher sampling accuracy than random sampling, systematic sampling, and adaptive web sampling.

The effect of electron beam incidence angle on the dynamic fracture of metal rings and cylinders

This work investigated how the incidence angle of the electron beam affects the dynamic fracture of metallic cylinder shell. Cylinder shell made of steel was blazed with electron beam and cut into ring and cylinder specimens. Flash X-ray radiography was used to register the fracture of the ring specimen. Fragments from the cylinder specimens under internal explosive loading were recovered and analyzed by SEM, and the fragment mass distribution was derived by statistical analysis. When the incident angle α of the electron beam was 0°, the fracture of the metal ring was along the normal direction of the outer surface. When α was 30° and 45°, the fracture of the metal ring was oblique. The distributions of recovered fragments were similar regardless of α. The fracture of the metallic cylinder shell under explosive loading was well controlled at all α. The recovered fragments from the cylinder specimen with α = 30° or 45° had an oblique quadrangular prism shape, whose the length was 30% larger than the fragments from the cylinder specimen with α = 0°. The fracture near the outer side of the cylinder specimen was along the melting region of the electron beam. The fracture mode of the cylinder specimen was tension-shear mixed fracture when α = 0° but shear fracture when α = 30° or 45°.

Oblique wrinkling patterns on liquid crystal polymer core–shell cylinders under thermal load

Smart soft materials, which can flexibly respond to external multi-physics stimuli, have attracted considerable attention over the past few years. Here, we present tunable wrinkling patterns in cylindrical core–shell systems under thermal load via the orientation of director in nematic liquid crystal polymer (LCP). To quantitatively analyze mechanical behavior and morphological evolution of LCP core–shell cylinders, we develop a core–shell model that accounts for director-induced anisotropic spontaneous strains. By tuning the alignment of liquid crystal director, we explore the effects of anisotropy of spontaneous strains on instability pattern formation and evolution. When the director is along the circumferential direction, wrinkling pattern can be axisymmetric or diamond-like, determined by a single dimensionless parameter Cs which characterizes the stiffness ratio and curvature of the system. When the director is parallel to the axial direction, leading to circumferential expansion upon heating, the core–shell cylinder usually buckles into churro-like mode. For general spatial director alignment, the ultimate wrinkling patterns depending on the anisotropy state of spontaneous strains, can be diamond-like, parallel bead-chain or oblique stripe mode. We draw director-affected phase diagrams to provide an overall view of pattern selection affected by liquid crystal director orientation, which could be used to quantitatively guide the effective design of wrinkling morphology-related smart surfaces.

A Comparison Investigation on Cylinder Test in Different Ambient Media by Experiment and Numerical Simulation

When the detonation reaction occurs after the charge in the warhead is ignited, the propagation of the detonation wave and the expansion of the detonation product will interact with the wrapped metallic shell and cause the shell material to accelerate, extremely deform, and eventually rupture, which is a typical strong fluid-structure interaction problem. In this paper, a comparison investigation on a cylinder test in different ambient media was implemented by experiment and numerical simulation, respectively. In the experimental test, the attention was paid to discussing the differences of the accelerating process of the cylinder metal wall, the expansion modes, and the fragment shape of the cylinder due to the medium with different shock wave impedance which surrounds the cylinder shell. For the numerical simulation, a coupling scheme of a meshless method and finite element method called the coupled finite element material point method was used to reproduce the cylinder expansion problem driven by explosive sliding detonation where the interaction between the cylinder wall and the explosive/detonation product is enforced by using a point-to-surface contact scheme to accurately achieve contact and separation between material particles and finite elements. Lastly, the macroscopic and microscopic states of the cylinder failure were compared and discussed for further discussion.

Disorder-immune metasurfaces with constituents exhibiting the anapole mode

Common optical metasurfaces are two-dimensional functional devices composed of periodically arranged subwavelength constituents. Here, we achieved the positional-disorder-immune metasurfaces composed of core–shell cylinders which successively exhibit the magnetic dipole (MD) resonant, non-radiating anapole, and electric dipole (ED) resonant modes when their outer radii are fixed and the inner radii change continuously in a range. The performances of the metasurfaces under a periodically structural design are not degraded even when the positions of the cylinders are subjected to random and considerable displacements. The positional-disorder-immunity is due to the weak non-local effect of the metasurfaces. Because the multiple scattering among cylinders is weak and insensitive to the spacing among the cylinders around the ED and MD resonant modes and vanishing irrespective of the spacing at the non-radiating anapole mode, the reflection properties including the reflection phase and reflectivity of the metasurfaces are insensitive to the spacing between neighboring cylinders for this entire variation range of the inner radius. Our findings can have important implications in understanding the underlying mechanism of the positional-disorder-immunity and provide a unique approach to achieve metasurfaces with various performances robust against large positional disorders. We expect the present work to open a door for the various applications of the metasurfaces in some harsh and unstable environments.

A three-dimensional solution for free vibration and buckling of annular plate, conical, cylinder and cylindrical shell of FG porous-cellular materials using IGA

This study aims to present a three-dimensional (3D) numerical solution for investigating the free vibration and buckling responses of annular plate, conical and cylindrical shell made of functionally graded (FG) porous rock materials. Isogeometric analysis (IGA) is utilized in order to develop the 3D numerical solution. Furthermore, the computational package is developed using C# Programming, which is an object-oriented programming language. The distribution of porosity along the thickness direction obeys the cosine function rule, for which the top surface is porosity-free, and the bottom surface is porosity-rich. The weak form for free vibration and buckling analyses are discretized and approximated through 3D NURBS based IGA. The accuracy of the present solutions is verified by the results obtained from published data. The convergence of 3D FGP solutions is checked, and it is found that a quartic NURBS element can yield high-accuracy results with the lowest computational cost. Afterward, the numerical results showed the impact of porosity of the FGP annular plate, FGP conical, and cylindrical shell on free vibration and buckling problems.

A freezing recovery method for metallic cylinder shells under internal explosive loading

Aimed to the recovery of expansive metal cylindrical shells subjected to internal explosive loading, the freezing recovery test method was developed to realize the freezing recovery of the metallic cylindrical shells at different moments after detonation. Based on the integrated shell, three improved structures were proposed, and the expansion and fracture processes of the four cylindrical shell structures under internal explosive loading were numerically simulated. It was found that the two-stage shell was the most beneficial to reduce the influence of the non-initiation end on the middle shell expected to be recovered. According to the selected optimal shell structure and the shape expansion characteristics of metal cylindrical shells at different moments after detonation, the freezing recovery devices matching with the shells were designed, and the freezing recovery tests were carried out. The test results show that the developed freezing recovery test method can realize the recovery of the expanded metallic cylindrical shells. The axial and radial dimensions of the recovery shells are in good agreement with the ideal design values, and the overall error can be controlled within 10%.

Three-dimensional nanodosimetric characterisation of proton track structure

This work presents a detailed investigation into the nanodosimetric properties of the track structure of protons in water at energies relevant for proton radiotherapy. The ionization component of the tracks had been simulated in previous work using Geant4-DNA for proton start energies between 1 MeV and 100 MeV. From the simulation results, the frequency distribution of ionization clusters formed in nanometric target volumes was obtained in dependence of the impact parameter of the proton trajectory with respect to the target center. In the track core, targets of cylindrical shape and a size comparable to a short segment of DNA were used for scoring ionization cluster size distributions. For the penumbra region, three different options for defining the cylinder shell sectors were investigated, with each cylinder shell sector volume the same as the cylinder target volume. The radial distributions were numerically integrated to obtain the effective track cross sections with respect to different nanodosimetric parameters. Graphically displaying the radial dependence in a similar way as microdosimetric distributions allowed elucidating the contribution of different radial distances to the overall radial integral of the quantities under consideration. Furthermore, it was tested how well the radial dependence of the nanodosimetric parameters could be fitted with a model function derived in literature for the radial energy deposition in proton tracks. It was found that this model function allows describing only the radial dependence of the total frequency of nanometric targets where ionizations occur. The deviation from a 1/r2-dependence of the radial dependence of the frequency of targets receiving more than a minimum number of ionizations (exceeding one) includes a second peak centred around 10 nm radial distance from the proton trajectory.

PROPAGATION OF LINEAR WAVES IN MULTILAYERED STRUCTURAL - INHOMOGENEOUS CYLINDRICAL SHELLS

In this paper, axisymmetric viscoelastic waves in an extended cylindrical shell of circular cross section are considered. The study of axisymmetric viscoelastic waves in multilayer cylindrical systems with the maximum possible use of analytical methods is relevant for the development of a new generation of sounding techniques for wells. The aim of the work is to study the propagation of axisymmetric viscoelastic waves in extended multilayer cylindrical structures, to determine the volumetric structure variant from the responses of one-way sounding using a priori information about the possible structure of the system. The paper uses classical methods of mathematical physics, applied to solving boundary value problems in a cylindrical coordinate system, the spatial Fourier transform, the method of complex amplitudes for the variable components of the displacement vector and the stress tensor. The low-frequency resonances of a cylindrical shell are investigated. The physical laws of the formation of the pitch of its fundamental tone are determined sounding. The impossibility of propagation along the casing of wells is proved low-frequency surface waves, as well as SH-polarization waves at axisymmetric excitation. The thin-walled cylindrical shell in the low-frequency region has two fundamental resonance associated with the resonance of the shell as a whole and resonance of each individual section as a ring. Beats of these frequencies the basic tone of the sound of an extended shell of this type is determined. At frequencies below the cutoff of higher modes, all the features of the dispersion natural waves in the wall of a circular cylinder shell are described approximate algebraic equation of the third degree. One the real root of this equation corresponds to the zero mode antisymmetric Lamb wave, and one of the other two complex conjugate, describes the zero mode of the symmetric wave.

Detumbling Method for Uncontrolled Satellite Based on Eddy Currents

For the capture and removal of a large uncontrolled rotating satellite, a detumbling method based on the electromagnetic principle is developed and verified. A numerical method, which applies to arbitrary shapes and a nonuniform field, is used to calculate the eddy current torque of a rotating conductor in magnetic field. The numerical result of a spinning cylinder in uniform field is compared with the analytical solution, and two sets of experiment for spinning cylinder and cuboid shell with open ends are carried out to verify the numerical results in a nonuniform field. The numerical results are in good agreement with the experiments. A detumbling strategy is proposed, and a numerical simulation is carried out taking a spinning cylinder as the hypothetical target of detumbling. The results show that the detumbling strategy is effective and the detumbling rate is greatly improved by applying the detumbling magnetic field.

On Certain Problems of Identification of Thermal Density of the Temperature State of the Hollow Cylinder Shell

Introduction. In conditions of the active use of composite materials, as when accomplishing the tasks of extending the service life of existing structures, problems on recovering unknown parameters of their components under the known data on their surface arise. In [1-4], to solve the problems of identification ofparameters of a wide range, it is proposed to construct explicit expressions of the gradients of residual functionals by means of the corresponding conjugate problems obtained from the theory of optimal control of the states of multicomponent distributed systems, which is the development of the corresponding researches of Zh. Lyons. In [5-7], this technology is extended to the problem of thermoelastic deformation of multicomponent bodies. In this article some problems of optimal control of the temperature state of a cylindrical body with a cavity are considered. The purpose of the paper is to show the algorithm for identifying the parameters of a cylindrical hollow shell, based on the theory of optimal control and using the gradient methods of Alifanov. Results. Based on the theory of optimal control, the temperature control of a cylindrical shell is studied. To solve the problem of identifying the parameters of a hollow cylindrical shell, namely, finding the heat flux powers on its surfaces, based on [1,2,5-7], a direct and conjugate problem and gradients of non-viscous functionals are constructed. Discretization by the finite element method using piecewise quadratic functions is carried out and accuracy estimates for it are presented. The initial problem in the model examples presented is solved using gradient methods, where at each step of determining the (n + 1) the approximation of the solution, the direct and adjoint problems are solved using finite element method with the help piecewise quadratic functions by minimizing the corresponding energy functional. A number of model examples solved.