Dynamics Of Shells Research Articles

Investigation of the nonlinear dynamics of thin sandwich shells composed of functionally graded materials with double curvature in thermal environments

Double curvature structures play a crucial role as load-bearing components across various engineering fields. Functionally graded materials, blending metals and ceramics, boast superior material characteristics, fueling their expanding applications. This study pioneers the non-linear dynamic analysis of sandwich shells that feature functional gradient compositions in thermal settings. We assume that both the upper and lower shells of these double curvature structures are crafted from functionally graded materials, with a ceramic core. This variation in material exhibits a ceramic layer on the inner surface and a metallic layer on the outer surface, showing properties that vary along the shell thickness in a power-law gradient. Non-linear dynamic equations are derived using third-order shear theory, encompassing geometric non-linearity and shear deformation. Employing the Galerkin method, we discretize the equations of motion into a non-linear dynamic system with five degrees of freedom, and subsequently give an analytical expression for the nonlinear naturalfrequency by means of multiscale analysis. Our discussion examines the impacts of structural parameters, porosity volume fraction, volume fraction index, and temperature differences on the non-linear/linear frequency ratio of doubly curved sandwich shells. Calculations reveal a sharp rise followed by a rapid decline in the non-linear/linear frequency ratio with increasing structural aspect ratio b/a. Conversely, it decreases with increasing thickness-to-length and radius-to-length ratios, with temperature differences initially reducing and later increasing it. These findings offer practical insights for designing functional gradient double curvature sandwich shells.

The Structural Diversity of Encapsulin Protein Shells.

Subcellular compartmentalization is a universal feature of all cells. Spatially distinct compartments, be they lipid- or protein-based, enable cells to optimize local reaction environments, store nutrients, and sequester toxic processes. Prokaryotes generally lack intracellular membrane systems and usually rely on protein-based compartments and organelles to regulate and optimize their metabolism. Encapsulins are one of the most diverse and widespread classes of prokaryotic protein compartments. They self-assemble into icosahedral protein shells and are able to specifically internalize dedicated cargo enzymes. This review discusses the structural diversity of encapsulin protein shells, focusing on shell assembly, symmetry, and dynamics. The properties and functions of pores found within encapsulin shells will also be discussed. In addition, fusion and insertion domains embedded within encapsulin shell protomers will be highlighted. Finally, future research directions for basic encapsulin biology, with a focus on the structural understand of encapsulins, are briefly outlined.

Scalar shell dynamics of quantum-corrected Schwarzschild black hole surrounded by quintessence field

Scalar shell dynamics of quantum-corrected Schwarzschild black hole surrounded by quintessence field

Vibrational heavy atom effect on relaxation and solvent shell dynamics in group VIII trimetallic carbonyls.

Infrared pump-probe and two-dimensional infrared (2D-IR) spectroscopies were used to study the vibrational dynamics of a homologous set of trimetallic dodecacarbonyls with increasingly heavy atomic masses in tetrahydrofuran solution. The vibrational lifetimes showed some evidence of the vibrational heavy atom effect (VHAE) but were not consistent across the sample set. Spectral diffusion was measured by 2D-IR spectroscopy to investigate whether the changes produced by the VHAE had influenced other aspects of vibrational dynamics. The triiron species was found to be more dynamic on very fast timescales and may exhibit evidence of a transient bridging CO structure. Centerline slope analysis of the high-frequency CO peak for each complex revealed that the vibrational dynamics were subtly but consistently slowed for the compounds with heavier metal atoms.

Nonlinear Dynamics of Fluid-Filled Nanocomposite Cylindrical Shells Surrounded by Non-Uniform Kerr Elastic Substrates

This paper presents a novel analytical framework for investigating the nonlinear dynamic response of functionally graded graphene platelets reinforced composite (FG-GPLRC) cylindrical shells filled with fluids and supported by non-uniform Kerr elastic substrates. The significance of this research lies in its comprehensive exploration of various substrate configurations achieved through discretizing the elastic substrates along the shell’s length. The fluid within the shell is characterized as non-viscous and incompressible, while material properties are rigorously determined using the rule of mixtures and the Halpin–Tsai micromechanical model. At the core of our method lies the establishment of nonlinear kinematic relationships rooted in Donnell shell theory and von Kármán’s nonlinear geometric postulates. We rigorously solve the equations of motion using Galerkin’s technique and the fourth-order Runge–Kutta method. Notably, our enhanced model efficiently accounts for the effect of discontinuities in the elastic foundation’s stiffness solely through integration operations, eliminating the need for intricate algorithms. This approach optimizes computational time and costs. The study conducts a comparative analysis of its results with existing literature, contributing to a thorough understanding of the validity of the proposed approach. We investigate various factors — including material properties, fluid characteristics, and geometric parameters — and their influence on the nonlinear response of nanocomposite shells. Our comprehensive analysis highlights the significant impact of substrate distribution, emphasizing its importance in structural design. Expanding the elastic base area and gradually shifting the elastic foundation toward the central region of the shell positively will affect various factors such as elevating natural frequency and reducing vibrational amplitudes.

Effects of Nanoconfinement on Dynamics in Concentrated Aqueous Magnesium Chloride Solutions.

Water behavior in various natural and manufactured settings is influenced by confinement in organic or inorganic frameworks and the presence of solutes. Here, the effects on dynamics from both confinement and the addition of solutes are examined. Specifically, water and ion dynamics in concentrated (2.5-4.2 m) aqueous magnesium chloride solutions confined in mesoporous silica (2.8 nm pore diameter) were investigated using polarization selective pump-probe and 2D infrared spectroscopies. Fitting the rotational and spectral diffusion dynamics measured by the vibrational probe, selenocyanate, with a previously developed two-state model revealed distinct behaviors at the interior of the silica pores (core state) and near the wall of the confining framework (shell state). The shell dynamics are noticeably slower than the bulk, or core, dynamics. The concentration-dependent slowing of the dynamics aligns with behavior in the bulk solutions, but the spectrally separated water-associated and Mg2+-associated forms of the selenocyanate probe exhibit different responses to confinement. The disparity in the complete reorientation times is larger upon confinement, but the spectral diffusion dynamics become more similar near the silica surface. The length scales that characterize the transition from surface-influenced to bulk-like behavior for the salt solutions in the pores are discussed and compared to those of pure water and an organic solvent confined in the same pores. These comparisons offer insights into how confinement modulates the properties of different liquids.

Unraveling the Hydration Shell Structure and Dynamics of Group 10 Aqua Ions.

We present ab initio simulations based on subsystem DFT of group 10 aqua ions accurately compared against experimental data on hydration structure. Our simulations provide insights into the molecular structures and dynamics of hydration shells, offering recalibrated interpretations of experimental results. We observe a soft, but distinct second hydration shell in Palladium (Pd) due to a balance between thermal fluctuations, metal-water interactions, and hydrogen bonding. Nickel (Ni) and platinum (Pt) exhibit more rigid hydration shells. Notably, our simulations align with experimental findings for Pd, showing axial hydration marked by a broad peak at about 3 Å in the Pd-O radial distribution function, revising the previously sharp "mesoshell" prediction. We introduce the "hydrogen bond dome" concept to describe a resilient network of hydrogen-bonded water molecules around the metal, which plays a critical role in the axial hydration dynamics.

Water Solvent Reorganization upon Ultrafast Resonant Stimulated X-ray Raman Excitation of a Metalloporphyrin Dimer.

We propose an X-ray Raman pump-X-ray diffraction probe scheme to follow solvation dynamics upon charge migration in a solute molecule. The X-ray Raman pump selectively prepares a valence electronic wavepacket in the solute, while the probe provides information about the entire molecular ensemble. A combination of molecular dynamics and ab initio quantum chemistry simulations is applied to a Zn-Ni porphyrin dimer in water. Using time-resolved X-ray diffraction and pair distribution functions, we extracted solvation shell dynamics.

Hydrophobic Clusters Regulate Surface Hydration Dynamics of Bacillus subtilis Lipase A.

The surface hydration diffusivity of Bacillus subtilis Lipase A (BSLA) has been characterized by low-field Overhauser dynamic nuclear polarization (ODNP) relaxometry using a series of spin-labeled constructs. Sites for spin-label incorporation were previously designed via an atomistic computational approach that screened for surface exposure, reflective of the surface hydration comparable to other proteins studied by this method, as well as minimal impact on protein function, dynamics, and structure of BSLA by excluding any surface site that participated in greater than 30% occupancy of a hydrogen bonding network within BSLA. Experimental ODNP relaxometry coupling factor results verify the overall surface hydration behavior for these BSLA spin-labeled sites similar to other globular proteins. Here, by plotting the ODNP parameters of relative diffusive water versus the relative bound water, we introduce an effective "phase-space" analysis, which provides a facile visual comparison of the ODNP parameters of various biomolecular systems studied to date. We find notable differences when comparing BSLA to other systems, as well as when comparing different clusters on the surface of BSLA. Specifically, we find a grouping of sites that correspond to the spin-label surface location within the two main hydrophobic core clusters of the branched aliphatic amino acids isoleucine, leucine, and valine cores observed in the BSLA crystal structure. The results imply that hydrophobic clustering may dictate local surface hydration properties, perhaps through modulation of protein conformations and samplings of the unfolded states, providing insights into how the dynamics of the hydration shell is coupled to protein motion and fluctuations.

Impact of charged and quantum-correction on the dynamics of scalar shell surrounded by Kiselev black hole

The objective of this study is to investigate the geometric configurations of a thin-shell in the framework of quantum-corrected charged Kiselev black holes. In order to do this, a cut and paste technique is employed to align the inner Minkowski spacetime with the black hole solutions under consideration. Our research explores the effects of quantum-correction on the stability of thin-shell using linearized radial perturbation method incorporating the phantomlike equation of state such as quintessence. This approach allows for the identification of stable configurations of the thin-shell situated beyond the expected location of the event horizon in the exterior manifold. Moreover, it is evident that the stability of the thin-shell is significantly dependent on the parameters associated with the black hole solutions. In this study, we investigate the dynamics of the thin-shell configuration using Klein–Gordon’s equation of motion, including both massive and massless scalar fields. The results of our study suggest that the presence of the scalar field has a significant impact on the behavior of the thin-shell, resulting in notable phenomena such as expansion and collapse. The aforementioned results provide valuable insights into the behavior of black hole solutions by examining the dynamics of thin-shells in relation to quantum-correction parameters involving scalar fields. In summary, it is observed that the presence of a quantum-correction parameter has the effect of reducing the stable configuration of a Kiselev black holes.

Nonlinear resonant responses and chaotic dynamics of three-dimensional braided composite cylindrical shell

The advanced three-dimensional braided composite structure has excellent integrity, which can effectively avoid the problems of interlayer stress jump and interface debonding that may occur in traditional composite laminated structures. However, most of the existing references on the three-dimensional braided composite structure are fragmented, and there is little research on their vibrations. Taking the cylindrical shell of a rocket as the object and considering the complex flight environment, a general framework for the vibration problems of the three-dimensional braided composite shell is proposed for the first time. The equivalent mechanical parameters of the three-dimensional braided composite material are calculated based on the volume averaging method. Then, the nonlinear dynamic model of the three-dimensional braided composite cylindrical shell is established, and the natural vibration characteristics are analyzed. Under the case of 1:1 internal resonance, the pseudo-arc length continuation method is used to solve the nonlinear resonant responses of this nonlinear system. Finally, we apply the fourth-order Runge-Kutta algorithm to study the chaotic dynamics of the three-dimensional braided composite cylindrical shell model. This framework presented in this paper can be extended to the study of nonlinear vibrations and chaotic dynamics of other three-dimensional braided composite structures.

The weak gravity conjecture, overcharged shells and gravitational traps

The Weak Gravity Conjecture (WGC) predicts that in quantum gravity there should exist overcharged states, that is states with charge larger than their mass. Extending this to large masses and charges, we are expecting similar overcharged classical solutions. This has been demonstrated in higher-derivative extensions of General Relativity. In this paper we investigate the existence of overcharged solutions in General Relativity. We study the dynamics of a thin shell of mass m and charge Q under the action of its own gravitational and U(1) fields. We show that shells with surface energy σ and pressure P obeying P=wσ with 0⩽w⩽1 are necessarily undercharged m⩾|Q| and always collapse to form Reissner–Nordström black holes. Nevertheless, if −1⩽w<0 , we find that overcharged m⩽|Q| shells exist, which however, are inevitably stabilized at finite radial distance. Therefore they never form naked singularities in accordance with cosmic censorship and the conjectured relation between cosmic censorship and the WGC. An intriguing consequence of the existence of such overcharged shells is that gravitational modes may form bound states due to the peculiar form of the Regge–Wheeler–Zerilli potential. This might lead to gravitational traps close the surface of near-overcharged shells.

Europa's Double Ridges Produced by Ice Wedging

AbstractDouble ridges are sprawling features observed globally across the icy surface of Europa. They consist of two topographic highs flanking a trough. The topographic relief of the ridges is approximately 100 m, and the ridges extend up to hundreds of kilometers in length. The interior structure and dynamics of Europa's ice shell are currently poorly constrained. Therefore, accurate models for the formation of these prominent surface features can be useful for determining how the ice shell operates. We hypothesize that double ridges form as a result of incremental ice wedging. We use both analytical and numerical finite element models to quantify the deformation that occurs as an ice wedge grows incrementally within the ice shell. We show that incremental growth of the ice wedge results in surface deformation that matches the size and shape of typical Europan double ridges, including their topographic relief and surrounding troughs. We find that as the depth of the ice wedge increases, double ridges become broader and shorter. We explore the possibility of local and non‐local sources for the liquid water that freezes to produce the wedge and ultimately argue in favor of local sources of liquid water within the ice shell.

On the dynamics of a rolling spherical charged shell

In this work, we investigate the behaviour of a charged spherical shell rolling on an inclined plane, in presence of a point charge located at the lowest part of the inclined plane. The shell generates two magnetic fields, one due to its rotation and another due to its translation, These magnetic fields affect the shell through self-inductance. On the other hand, the charge in the lowest part of the inclined plane interacts with the shell, and we find that under certain conditions the spherical shell rolls back and up the inclined plane due to the electric force. We perform a numerical analysis to study this behavior.

DIFFERENTIAL EQUATIONS OF THE DEVICE SHELL WITH ARBITRARY GEOMETRY OF THE MERIDIAN LINE

The theory describes the shell part of the apparatus as a surface with an arbitrary geometric outline and general acting factors. A mathematical model is constructed, and boundary conditions are formulated to determine the coordinate deformation functions of the shell part under any external disturbances. The methodology for calculating the elastic deformations of its surface with an arbitrary outline of the meridian line is also described. When analyzing the nature of a phenomenon and determining how to combat negative impacts on inertial navigation devices caused by certain factors, it is crucial to calculate the coordinate functions of the deformation of the vehicle's shell under the influence of spatial disturbances. It has been proved that inaccuracies or excessive simplifications lead to errors in the integration of the shell equations, and thus to errors in the calculation of the coordinate functions of the surface deformation and distortion of the meaning of the phenomenon. The equations for determining partial frequencies have been developed, revealing that oscillatory processes on the float's surface affect each other in all directions. Therefore, it is possible to determine the degree of influence for specific mass and dimensional modifications of the RMS. The scientific foundations have been laid for a deep analysis of the dynamics of the vehicle's shell under full-scale conditions. Additionally, a reasoned comparative analysis with the classical cylindrical modification of the float has been revealed. It is now possible to optimize the weight and size characteristics of the device. Theoretical foundations for improving the accuracy and reliability of float devices (and inertial navigation systems in general) are being developed based on passive methods of sound insulation and their combination with other methods, such as active and auto-compensation.

Dynamics of Sandwich Cylindrical Shells with Inhomogeneous Core Under Operational Loads

Dynamics of Sandwich Cylindrical Shells with Inhomogeneous Core Under Operational Loads

Altering Na-ion solvation to regulate dendrite growth for a reversible and stable room-temperature sodium–sulfur battery

Theoretical calculation reveals that the additive (BiI3) changes the local solvation shell dynamics and improves the Na ion kinetics by reducing binding energy. In addition, the formation of an alloy interphase realizes a dendrite-free deposition.

Research on the dynamics of lightweight shell and spatial structures with the aid of computational fluid dynamics and a shaking table

Research on the dynamics of lightweight shell and spatial structures with the aid of computational fluid dynamics and a shaking table

Evolution of solitary hydroelastic strain waves in two coaxial cylindrical shells with the Schamel physical nonlinearity

The paper considers the formulation and solution of the hydroelasticity problem for studying wave processes in the system of two coaxial shells containing fluids in the annular gap between them and in the inner shell. We investigate the axisymmetric case for Kirchhoff–Lave type shells whose material obeys a physical law with a fractional exponent of the nonlinear term (Schamel nonlinearity). The dynamics of fluids in the shells is considered within the framework of the incompressible viscous Newtonian fluid model. The derivation of the Schamel nonlinear equations of shell dynamics makes it possible to develop a mathematical formulation of the problem, which includes the obtained equations, the dynamics equations of two shells, the fluid dynamics equations and the boundary conditions at the shell-fluid interfaces and at the flow symmetry axis. The asymptotic analysis of the problem is performed using perturbation techniques, and the system of two generalized Schamel equations is obtained. This system describes the evolution of nonlinear solitary hydroelastic strain waves in the coaxial shells filled with viscous fluids, taking into account the inertia of the fluid motion. In order to determine the fluid stress at the shell-fluid interfaces, we perform linearization of the fluid dynamics equations for fluids in the annular gap and in the inner shell. The linearized equations are solved by the iterative method. The inertial terms are excluded from the equations in the first iteration, while, in the second iteration, these are the values found in the first iteration. A numerical solution of the system of nonlinear evolution equations is obtained by applying a new difference scheme developed using the Gröbner basis technique. Computational experiments are performed to investigate the effect of fluid viscosity and the inertia of fluid motion in the shells on the wave process. In the absence of fluids in the inner shell, the results of calculations demonstrate that the strain waves in the shells during elastic interactions do not change their shape and amplitude, i.e., they are solitons. The presence of viscous fluid in the inner shell leads to attenuation of the wave process.

Numerical predictions of intralaminar and interlaminar damage in thin composite shells subjected to impact loads

This paper investigates the impact dynamics of thin semicylindrical woven composite laminate shells, with a particular focus on understanding the influence of thickness. Utilizing the finite element (FE) method, the study evaluates both intralaminar and interlaminar damage associated with the impact response. The findings show that the implementation of the explicit FE method, along with a continuum damage mechanics model, for the intralaminar damage, and a surface-based cohesive model, for the interlaminar damage, may be used to correctly predict the load histories, as well as the maximum impact force, maximum displacement, contact time and impact bending stiffness (IBS). The numerical predictions reproduce well the linear response of the maximum impact force and maximum displacement to the thickness variation, as well as the 2nd order polynomial curve of the IBS, with errors ranging from 2.7% to 15.9%. Moreover, the damage areas and the effect of thickness on the damage severity were accurately replicated. These results’ validation enables the prediction of the energy histories and the ensuing energy dissipation forms. According to the findings, the intralaminar damage is around 5 times more significant than the other energy dissipation forms. The accuracy of the simulation creates the possibility for more impact investigations using a similar numerical approach, reducing the expenditures of experimental testing.