Dynamics Of Shells Research Articles

Study on the melting dynamics of latent heat storage for various orientations, shell shapes, and eccentricity

In this research, the melting dynamics of NaNO2-based shell and tube-type latent heat storage are comparatively evaluated for various orientations of the storage (vertical and horizontal) and various shell shapes (cylindrical and frustum). Furthermore, the performance of the various storage configuration is compared with the horizontal cylindrical storage having bottom eccentricity in the heat transfer fluid passage. The enthalpy porosity method is incorporated to evaluate the thermal behaviour of the various storage configurations. A total reduction in the charging time is noticed as 18.42% and 34.21%, respectively, in the vertical frustum storage and horizontal cylindrical storage unit as compared to the vertical cylindrical storage unit. It is revealed that the accelerated melt front movement along the entire length of the storage improves the heat transfer in the horizontal cylindrical storage units. At 250 min of the charging cycle, horizontal cylindrical storage stores 100% of the targeted energy, while vertical cylindrical storage and vertical frustum storage store only 80% and 90%, respectively, of the targeted energy storage capacity. The enlarged melt front developed by the downward eccentric shifting of the inner heat transfer fluid passage further augments the heat transfer rate in the horizontal cylindrical storage. The total charging time of the horizontal cylindrical storage is noticed as 250 min, 230 min, 210 min, 200 min, and 190 min for bottom eccentric locations of 0 mm, 5 mm, 10 mm, 15 mm, and 20 mm, respectively. A 20 mm shifting of the inner tube results in a maximum curtailment of 24% in the charging time of the storage than the horizontal cylindrical storage having a concentric inner tube.

An In Situ Investigation of the Protein Corona Formation Kinetics of Single Nanomedicine Carriers by Self-Regulated Electrochemiluminescence Microscopy.

Protein coronas are present extensively at the bio-nano interface due to the natural adsorption of proteins onto nanomaterials in biological fluids. Aside from the robust property of nanoparticles, the dynamics of the protein corona shell largely define their chemical identity by altering interface properties. However, the soft coronas are normally complex and rapidly changing. To real-time monitor the entire formation, we report here a self-regulated electrochemiluminescence (ECL) microscopy based on the interaction of the Ru(bpy)3 3+ with the nanoparticle surface. Thus, the heterogeneity of the protein corona is in situ observed in single nanoparticle "cores" before and after loading drugs in nanomedicine carriers. The label-free, optical stable and dynamic ECL microscopy minimize misinterpretations caused by the variation of nanoparticle size and polydispersity. Accordingly, the synergetic actions of proteins and nanoparticles properties are uncovered by chemically engineered protein corona. After comparing the protein corona formation kinetics in different complex systems and different nanomedicine carriers, the universality and accuracy of this technique were well demonstrated via the protein corona formation kinetics curves regulated by competitive adsorption of Ru(bpy)3 3+ and multiple proteins on surface of various carriers. The work is of great significance for studying bio-nano interface in drug delivery and targeted cancer treatment.

An In Situ Investigation of the Protein Corona Formation Kinetics of Single Nanomedicine Carriers by Self‐Regulated Electrochemiluminescence Microscopy

AbstractProtein coronas are present extensively at the bio‐nano interface due to the natural adsorption of proteins onto nanomaterials in biological fluids. Aside from the robust property of nanoparticles, the dynamics of the protein corona shell largely define their chemical identity by altering interface properties. However, the soft coronas are normally complex and rapidly changing. To real‐time monitor the entire formation, we report here a self‐regulated electrochemiluminescence (ECL) microscopy based on the interaction of the Ru(bpy)33+ with the nanoparticle surface. Thus, the heterogeneity of the protein corona is in situ observed in single nanoparticle “cores” before and after loading drugs in nanomedicine carriers. The label‐free, optical stable and dynamic ECL microscopy minimize misinterpretations caused by the variation of nanoparticle size and polydispersity. Accordingly, the synergetic actions of proteins and nanoparticles properties are uncovered by chemically engineered protein corona. After comparing the protein corona formation kinetics in different complex systems and different nanomedicine carriers, the universality and accuracy of this technique were well demonstrated via the protein corona formation kinetics curves regulated by competitive adsorption of Ru(bpy)33+ and multiple proteins on surface of various carriers. The work is of great significance for studying bio‐nano interface in drug delivery and targeted cancer treatment.

Disk Wind–Driven Expanding Radio-emitting Shell in Tidal Disruption Events

We study the evolution of a nonrelativistically expanding thin shell in radio-emitting tidal disruption events (TDEs) based on a one-dimensional spherically symmetric model considering the effect of both a time-dependent mass-loss rate of the disk wind and the ambient mass distribution. The analytical solutions are derived in two extreme limits; one is the approximate solution near the origin in the form of the Taylor series, and the other is the asymptotic solution in which the ambient matter is dominant far away from the origin. Our numerical solutions are confirmed to agree with the respective analytical solutions. We find that no simple power law of the time solution exists in early to middle times because the mass-loss rate varies over time, affecting the shell dynamics. We also discuss the application of our model to the observed radio-emitting TDE, AT 2019dsg.

Proof-of-Principle Experiment on the Dynamic Shell Formation for Inertial Confinement Fusion.

In the dynamic-shell (DS) concept [V. N. Goncharov et al., Novel Hot-Spot Ignition Designs for Inertial Confinement Fusion with Liquid-Deuterium-Tritium Spheres, Phys. Rev. Lett. 125, 065001 (2020).PRLTAO0031-900710.1103/PhysRevLett.125.065001] for laser-driven inertial confinement fusion the deuterium-tritium fuel is initially in the form of a homogeneous liquid inside a wetted-foam spherical shell. This fuel is ignited using a conventional implosion, which is preceded by a initial compression of the fuel followed by its expansion and dynamic formation of a high-density fuel shell with a low-density interior. This Letter reports on a scaled-down, proof-of-principle experiment on the OMEGA laser demonstrating, for the first time, the feasibility of DS formation. A shell is formed by convergent shocks launched by laser pulses at the edge of a plasma sphere, with the plasma itself formed as a result of laser-driven compression and relaxation of a surrogate plastic-foam ball target. Three x-ray diagnostics, namely, 1D spatially resolved self-emission streaked imaging, 2D self-emission framed imaging, and backlighting radiography, have shown good agreement with the predicted evolution of the DS and its stability to low Legendre mode perturbations introduced by laser irradiation and target asymmetries.

Symmetry breaking in core-valence double ionisation of allene

Conventional electron spectroscopy is an established one-electron-at-the-time method for revealing the electronic structure and dynamics of either valence or inner shell ionized systems. By combining an electron-electron coincidence technique with the use of soft X-radiation we have measured a double ionisation spectrum of the allene molecule in which one electron is removed from a C1s core orbital and one from a valence orbital, well beyond Siegbahns Electron-Spectroscopy-for-Chemical-Analysis method. This core-valence double ionisation spectrum shows the effect of symmetry breaking in an extraordinary way, when the core electron is ejected from one of the two outer carbon atoms. To explain the spectrum we present a new theoretical approach combining the benefits of a full self-consistent field approach with those of perturbation methods and multi-configurational techniques, thus establishing a powerful tool to reveal molecular orbital symmetry breaking on such an organic molecule, going beyond Löwdins standard definition of electron correlation.

Influence of the storage orientation and shell shape on the melting dynamics of shell and tube-type cascade latent heat storage

Latent heat storage is one of the cost-competitive storage solutions for various temperature applications (paraffin having a melting temperature of −30℃ used for ultra-low temperature applications (cold storage) to the molten salts having a melting temperature of 996℃ used for very high-temperature application (power generation)). In this work, an enthalpy porosity method-based approach is being implemented for the comparative assessment of various storage configurations such as 1-stage NaNO3 storage, 1-stage NaNO2 storage, and their 2-stage cascaded storage configurations. All the tested storages are designed for the latent energy accumulation capacity of 1 MJ. The existing research works on the performance enhancement of latent heat storage by changing the orientation of the storage system have highlighted contradictory observations. Efforts are made to underline the impact of the various geometric orientations and shell shapes on the melting behavior of the cascade latent heat storage. It is concluded that the horizontal cylindrical cascade storage completes the charging in 39.04 %, 15.78 %, 24.70 %, and 5.9 % less charging time than the other storage configurations, i.e., 1-stage NaNO3 storage, 1-stage NaNO2 storage, vertical frustum cascade storage, and vertical cylindrical cascade storage, respectively. In vertical cascade storages, the frustum shell increases the energy accumulation cycle time by 25 % as compared to the cylindrical shell. Furthermore, it is observed that horizontal cylindrical cascade storage takes 13.33 % less time to achieve the 50 % of the charging as compared to the vertical cylindrical cascade storage, but this difference reduces to 5.9 % for achieving 100 % of the charging state, which makes it more suited for part load charging conditions.

Ice dynamic recrystallization within Europa's ice shell: Implications for solid-state convection

Solid-state convection has been proposed to occur within Europa's ice shell based both on the interpretation of observed geological activity during Galileo spacecraft exploration and theoretical investigations. Laboratory experiments have investigated the effect of grain size insensitive creep and grain size sensitive creep on the ductile behaviour of polycrystalline ice. The ice grain size and the ice impurities content and, consequently, the viscosity of the ice within Europa's ice shell are poorly constrained, limiting the possibility to understand if solid-state convection can occur under Europa's ice shell conditions. To investigate how diurnal tidal flexing and the internal dynamics of Europa's ice shell influence the ice grain crystals' evolution, we adopted a thermal-mechanical numerical model that uses finite differences and marker-in-cell techniques, implementing the dynamic recrystallization of the ice and the ice grain evolution in a self-consistent way with the numerical model. We found that solid-state convection within Europa's ice shell can occur if it is diurnally tidally deformed, as the tidal stresses within the ice shell operate to reduce the ice grain sizes and the ice viscosity. We discuss future radio science experiments, in combination with radar sounder investigations, that will be capable of characterizing the possible presence of solid-state convection within Europa's ice shell.

Cavitation dynamics of the semi-sealed cylindrical shell during high-speed water entry

This paper experimentally investigates the vertical high-speed water entry of a semi-sealed cylindrical shell, which has one end sealed and one end opened. The unsteady water-entry cavitating flow characteristics of the shell are analyzed, and the evolution of cavities and jet impacts with different structures is studied. The results show that a nested multi-cavity is generated due to the self-jet phenomenon during water entry. The jet causes the diameter of the secondary cavity to be much larger than that of the primary cavity, and the morphology of the secondary cavity is more atomized. Due to the irregular motion of the jet, the primary cavity undergoes neck-shrinking phenomenon and is compressed, and the neck-shrinking position moves up as the secondary cavity grows. After secondary impact, a small jet appears at the bottom of the shell, which ejects out from the shell and increases the size of the bottom cavity, leading to the formation of quaternary cavity. Moreover, as the inner wall length increases, the time of the primary jet is advanced, while the depth of secondary cavity shortens. With the increase in the thickness, cavity shape becomes more similar to traditional supercavity, and the maximum diameter of the primary cavity increases.

Dynamics of Asymmetric Three-Layer Hemispherical Shells with a Discrete-Inhomogeneous Filler Under Pulsed Loads

Dynamics of Asymmetric Three-Layer Hemispherical Shells with a Discrete-Inhomogeneous Filler Under Pulsed Loads

Dynamics of Asymmetric Three-Layer Spherical Shells with a Discretely Inhomogeneous Core Under Nonstationary Loading*

Dynamics of Asymmetric Three-Layer Spherical Shells with a Discretely Inhomogeneous Core Under Nonstationary Loading*

Quantum dynamics of gravitational massive shell

The quantum dynamics of a self-gravitating thin matter shell in vacuum has been considered. Quantum Hamiltonian of the system is positive definite. Within chosen set of parameters, the quantum shell bounces above the horizon. Considered quantum system does not collapse to the gravitational singularity of the corresponding classical system.

Measuring the energy landscape: an experimental approach to the study of buckling in thin shells.

Recent research into the buckling load of thin shells has focused on local poking of the shell. In this approach, the shell is poked under load to extract its stability landscape, and a ridge tracking method is performed to estimate the buckling load of the shell. It is the current understanding that the stability landscape measures the local stability of the shell and, as a result, that the accuracy of ridge tracking greatly relies on the location of poking. Currently, there is no method that can predict where poking should be performed on an experimental system. Here, we examine the global response of thin shells to poking through the energy landscape. We present an experimental method for measuring the energy landscape of thin shells and demonstrate its application on a thin plate strip. We show that by analysing the dynamics of the shell in the energy landscape we can experimentally measure the buckling mode of the system, which gives the correct point of poking for accurate ridge tracking, and identify two kinds of buckling points. Finally, we propose how this approach can be applied to more complex systems such as thin cylinders. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.

Snap buckling of bistable beams under combined mechanical and magnetic loading.

We investigate the mechanics of bistable, hard-magnetic, elastic beams, combining experiments, finite-element modelling (FEM) and a reduced-order theory. The beam is made of a hard magneto-rheological elastomer, comprising two segments with antiparallel magnetization along the centreline, and is set into a bistable curved configuration by imposing an end-to-end shortening. Reversible snapping is possible between these two stable states. First, we experimentally characterize the critical field strength for the onset of snapping, at different levels of end-to-end shortening. Second, we perform three-dimensional FEM simulations using the Riks method to analyse high-order deformation modes during snapping. Third, we develop a reduced-order centreline-based beam theory to rationalize the observed magneto-elastic response. The theory and simulations are validated against experiments, with an excellent quantitative agreement. Finally, we consider the case of combined magnetic loading and poking force, examining how the applied field affects the bistability and quantifying the maximum load-bearing capacity. Our work provides a set of predictive tools for the rational design of one-dimensional, bistable, magneto-elastic structural elements. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.

Asymptotic derivation of a higher-order one-dimensional model for tape springs.

We derive a one-dimensional model for tape springs. The derivation starts from nonlinear thin-shell theory and uses a dimension reduction technique that combines a centreline-based parametrization of the tape-spring midsurface with the assumption that the strain varies slowly along the length of the tape spring. The one-dimensional model is effectively a higher-order rod model: at leading order, the strain energy depends on the extensional, bending and twisting strains and is consistent with classical results from the literature; the two following orders are novel and capture the dependence of the strain energy on the strain gradients. The cross-sectional displacements are solved as part of the dimension reduction process, making the one-dimensional model asymptotically exact. We expect that the model will accurately and efficiently capture the deformations and instabilities in tape springs, including those involving highly localized deformations. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.

Pseudo-bistability of viscoelastic shells.

Viscoelastic shells subjected to a pressure loading exhibit rich and complex time-dependent responses. Here we focus on the phenomenon of pseudo-bistability, i.e. a viscoelastic shell can stay inverted when pressure is removed, and snap to its natural shape after a delay time. We model and explain the mechanism of pseudo-bistability with a viscoelastic shell model. It combines the small strain, moderate rotation shell theory with the standard linear solid as the viscoelastic constitutive law, and is applicable to shells with arbitrary axisymmetric shapes. As a case study, we investigate the pseudo-bistable behaviour of viscoelastic ellipsoidal shells. Using the proposed model, we successfully predict buckling of a viscoelastic ellipsoidal shell into its inverted configuration when subjected to an instantaneous pressure, creeping when the pressure is held, staying inverted after the pressure is removed, and eventually snapping back after a delay time. The stability transition of the shell from a monostable, temporarily bistable and eventually back to the monostable state is captured by examining the evolution of the instantaneous pressure-volume change relation at different time of the holding and releasing process. A systematic parametric study is conducted to investigate the effect of geometry, viscoelastic properties and loading history on the pseudo-bistable behaviour. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.

Buckling of lipidic ultrasound contrast agents under quasi-static load.

Collapse of lipidic ultrasound contrast agents under high-frequency compressive load has been historically interpreted by the vanishing of surface tension. By contrast, buckling of elastic shells is known to occur when costly compressible stress is released through bending. Through quasi-static compression experiments on lipidic shells, we analyse the buckling events in the framework of classical elastic buckling theory and deduce the mechanical characteristics of these shells. They are then compared with that obtained through acoustic characterization. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.

Probing in situ capacities of prestressed stayed columns: towards a novel structural health monitoring technique.

Prestressed stayed columns (PSCs) are structural systems whose compressive load-carrying capacity is enhanced through pre-tensioned cable stays. Much research has demonstrated that PSCs buckle subcritically when their prestressing levels maximize the critical buckling load of the theoretically perfect arrangement. Erosion of the pre-tensioned cables' effectiveness (e.g. through creep or corrosion) can thus lead to sudden collapse. The present goal is to develop a structural health monitoring (SHM) technique for in-service PSCs that returns the current structural utilization factor based on selected probing measurements. Hence, PSCs with different cable erosion and varying compression levels are probed in the pre-buckling range within the numerical setting through a nonlinear finite element (FE) model. In contrast to the previous work, it is found presently that the initial lateral stiffness from probing a PSC provides a suitable health index for in-service structures. A machine learning-based surrogate is trained on simulated data of the loading factor, cable erosion and probing indices; it is then used as a predictive tool to return the current utilization factor for PSCs alongside the level of cable erosion given probing measurements, showing excellent accuracy and thus provides confidence that an SHM technique based on probing is indeed feasible. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.

3D-printing and cylinder buckling: challenges and opportunities.

Cylinder buckling is notoriously sensitive to small geometric imperfections. This is an underlying motivation for the use of knock-down factors in the design process, especially in circumstances in which minimum weight is a key design goal, an approach well-established at NASA, for example. Not only does this provide challenges in the practical design of this commonly occurring structural load-bearing configuration, but also in the carefully controlled laboratory setting. The recent development of 3D-printing (additive manufacturing) provides an appealing experimental platform for conducting relatively high-fidelity experiments on the buckling of cylinders. However, in addition to geometric precision, there are a number of shortcomings with this approach, and this article seeks to describe the challenges and opportunities associated with the use of 3D-printing in cylinder buckling in general, and probing the robustness of equilibrium configurations in particular. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.

Increasing reliability of axially compressed cylinders through stiffness tailoring and optimization.

The capabilities of the rapid tow shearing (RTS) process are explored to reduce the well-known imperfection sensitivity of axially compressed cylindrical shells. RTS deposits curvilinear carbon fibre tapes with a fibre-angle-thickness coupling that enables the in situ manufacturing of embedded rings and stringers. By blending the material's elastic modulus and wall thickness smoothly across the cylindrical surface, the load paths can be redistributed favourably with a minimal-design approach that contains part count and weight while ameliorating imperfection sensitivity. A genetic algorithm that incorporates realistic manufacturing imperfections and axial stiffness penalty is used to maximize the 99.9% reliability load of straight fibre (SF) and RTS cylinders. The axial stiffness penalty ensures that reliability does not come at the expense of stiffness. The first-order second-moment method is used to calculate statistical moments that enable an estimate of the 99.9% reliability load. Due to the fibre-angle-thickness coupling of RTS, buckling data are normalized by mass and thickness. Compared to a quasi-isotropic laminate, which corresponds to the optimal eight-layer design for a perfect cylinder, the optimized SF and RTS laminates have a 6% and 8% greater 99.9% normalized reliability load. By relaxing the axial stiffness penalty, the performance benefit can be increased such that SF and RTS cylinders exceed the 99.9% normalized reliability load of an eight-layer quasi-isotropic laminate by 23% and 37%, respectively. Both improvements (with and without penalty functions) stem largely from a reduction in the variance of the buckling-load distribution, thereby demonstrating the potential of fibre-steered cylinders in reducing the imperfection sensitivity of cylindrical shells. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.