Dynamic Stability Properties Research Articles

Assessment of Added Masses Effects on Airship Dynamics and Stability

Airships have recently emerged as attractive candidates for several aerospace applications, leading to an increasing interest in the modeling of the dynamic behavior of these vehicles for flight mechanics analyses and mission simulation purposes. One of the peculiarities of the airship model is the need for the inclusion of the dynamic effects due to the mutual interaction between the moving vehicle and the fluid in which it flies. This phenomenon is usually represented by introducing fictitious added masses. This paper presents a method to rigorously manage the added masses, including them in the flight dynamics equations without considering any simplifying assumptions concerning airship shape or centers of added mass. The paper also defines a method for the computation of the added mass matrix and centers of added mass position in any reference frame, which is required for the accurate writing of the airship equations of motion. The effectiveness of the proposed approach is validated numerically by solving a potential flow problem through the boundary element method. Finally, the effects of added masses are assessed with reference to a high-altitude airship by evaluating its dynamic stability properties with and without the inclusion of the added masses.

Structural and physical properties of the MAX phases RE2SX (RE = La ∼ Lu; X=B, C, N) via first-principles calculations

MAX phase layered compounds have high temperature stability, excellent mechanical properties, good thermal conductivity and electronic properties. In order to provide a certain theoretical basis for further experimental exploration of the MAX phase with rare-earth (RE) element, a detailed study of the RE2SX (RE = La∼Lu, X = B, C, N) MAX phase has been performed by using first-principles calculations. The study comprehensively examines the mechanical properties, elastic anisotropy, dynamical stability and thermal properties of the RE2SX phase, and the results demonstrate that 37 RE2SX phases satisfied the thermodynamical, mechanical and dynamical stabilities among the 45 compounds. The mechanical properties of the 37 stable phases were systematically analyzed, including bulk modulus, shear modulus, Young's modulus and hardness. Among these phases, La2SN, Ce2SB/N, Pr2SB/N, Nd2SB/N, Pm2SB, Sm2SB, Eu2SB, and Gd2SB were identified as exhibiting promising ductility potential. In the RE2SX carbides, the occupied states on the Fermi level of the RE2SC phase are very small, with the conduction band is mainly occupied by the valence electrons of the RE and S atoms, suggesting that these carbides exhibit notable electronic characteristics. These results can enhance our understanding of RE2SX phases and provide valuable guidance for future experimental research.

Innovative double perovskite: unveiling the dynamical stability, optoelectronic, magnetic and transport properties of Ba2CrWO6 for thermoelectric and optical applications

Innovative double perovskite: unveiling the dynamical stability, optoelectronic, magnetic and transport properties of Ba2CrWO6 for thermoelectric and optical applications

Nb-based copper sulvanites for potential green energy harvesting under induced isotropic pressure

This work explores the mechanical, electronic, dynamical stability, optical, and thermoelectric properties of Nb-based copper sulvanite compounds Cu3NbX4 (X=S, Se, Te) at 0, 5, 10, 15, and 20 GPa isotropic pressure within the framework of density functional theory (DFT). Calculated results are found in good agreement with experimental data, specifically in the values of their lattice parameters and optical band gaps. Cu3NbX4 exhibits promising optical properties for photovoltaic applications with enhanced properties under pressure. Exploration on transport properties also shows moderate thermoelectric figure of merit with slight improvement under pressure.

Dynamic stability and vibration isolation property of a foot-leg coupling bio-inspired vibration isolation structure

Dynamic stability and vibration isolation property of a foot-leg coupling bio-inspired vibration isolation structure

Strain-tunable electronic structure, optical and thermoelectric properties of BAs

Strain engineering stands as a reliable method for tailoring the physicochemical properties of materials to achieve desired performance. However, the effects of strain on the physicochemical properties of BAs remain unclear, impeding the comprehensive understanding of its practical performance. Here, employing first-principles calculations coupled with semiclassical Boltzmann transport theory, we investigate the dynamic stability, mechanical stability, electronic structure, and thermoelectric properties of cubic boron arsenide (BAs) under various strains. The results demonstrate that BAs maintains excellent stability throughout the triaxial strain range. The electronic structure of BAs is less affected by strain. Young’s modulus and Poisson’s ratio show a corresponding linear increase when the compression strain increases. The optical absorption coefficient in the visible region of BAs under tensile strain showed an overall increasing trend, and the optical absorption coefficient in the visible wavelength region of BAs under 5% tensile strain was as high as 2 × 105 cm−1. The thermoelectric properties of BAs under tensile strain have been improved, and the ZT value of BAs under 5% tensile strain at 1500 K has been increased to 0.6. The research findings address the gaps in understanding the properties of BAs under strain and provide theoretical support for its applications in the fields of thermoelectrics and optoelectronics.

Dynamical stability, electronic and optical properties of AcAlO3 perovskite using mBJ and hybrid functionals: A DFT approach

The structural, elastic, electronic, and optical properties of perovskite AcAlO3 were examined using DFT. First, the dynamical stability of the crystal in the cubic phase was ensured by the phonon dispersion curves. The elastic moduli suggest that the perovskite is mechanically hard and brittle. The 3D elastic moduli surfaces signify moderate elastic anisotropy. To precisely predict the band gaps, the band structures are analyzed using mBJ and YS-PBE0 screened hybrid functionals. Both mBJ and hybrid schemes offer similar band structures with direct band gaps of about 5.6 eV. The optical absorption in the perovskite is prominent in the UV-C region due to the ultra-wide band gap nature and may find suitable application in deep UV photodetectors.

Study of structural, dynamical stability, electronic magnetic and optical properties of RbSnO3 oxide perovskite compound using the density functional theory approach

This study investigates the structural, phonon, elastic, electronic, magnetic and optical properties of cubic perovskite RbSnO3. The calculations are based on the linearized augmented plane wave method with total potential (FP-LAPW), implemented in the Wien2k code; two approximations are used for calculate properties, PBE-GGA and TB-mBJ . The values of the tolerance factor and the formation energy of this material indicate that it is stable in the cubic structure of Pm3̅m symmetry. The Born criteria for the compound under study confirm its mechanical stability, while its phonon dispersion curves confirm its dynamic stability. The results of the electronic and magnetic properties show that the compound is ferromagnetic (FM) semi-metallic (DM) with semiconductor behavior in the majority spin channel and with an indirect gap in the M → Γ direction and having a total magnetic moment equal to 1 μB and a Curie temperature equal to 527 K. Optical spectra of the compound show high optical conductivity in the infrared region and towards the end of the spectrum at around 6 eV, high reflection in the infrared region with a maximum at 0.25 eV, and high absorption in the ultraviolet region at 6 eV. In view of these results, the RbSnO3 perovskite can be a promising candidate for spintronics applications as it can be used in optical devices working in the ultraviolet (UV) light region.

Quantum mechanical analysis of yttrium-stabilized zirconia and alumina: implications for mechanical performance of esthetic crowns

BackgroundYttrium-stabilized zirconia (YSZ) and alumina are the most commonly used dental esthetic crown materials. This study aimed to provide detailed information on the comparison between yttrium-stabilized zirconia (YSZ) and alumina, the two materials most often used for esthetic crowns in dentistry.MethodologyThe ground-state energy of the materials was calculated using the Cambridge Serial Total Energy Package (CASTEP) code, which employs a first-principles method based on density functional theory (DFT). The electronic exchange–correlation energy was evaluated using the generalized gradient approximation (GGA) within the Perdew (Burke) Ernzerhof scheme.ResultsOptimization of the geometries and investigation of the optical properties, dynamic stability, band structures, refractive indices, and mechanical properties of these materials contribute to a holistic understanding of these materials. Geometric optimization of YSZ provides important insights into its dynamic stability based on observations of its crystal structure and polyhedral geometry, which show stable configurations. Alumina exhibits a distinctive charge, kinetic, and potential (CKP) geometry, which contributes to its interesting structural framework and molecular-level stability. The optical properties of alumina were evaluated using pseudo-atomic computations, demonstrating its responsiveness to external stimuli. The refractive indices, reflectance, and dielectric functions indicate that the transmission of light by alumina depends on numerous factors that are essential for the optical performance of alumina as a material for esthetic crowns. The band structures of both the materials were explored, and the band gap of alumina was determined to be 5.853 eV. In addition, the band structure describes electronic transitions that influence the conductivity and optical properties of a material. The stability of alumina can be deduced from its bandgap, an essential property that determines its use as a dental material. Refractive indices are vital optical properties of esthetic crown materials. Therefore, the ability to understand their refractive-index graphs explains their transparency and color distortion through how the material responds to light..The regulated absorption characteristics exhibited by YSZ render it a highly attractive option for the development of esthetic crowns, as it guarantees minimal color distortion.ConclusionThe acceptability of materials for esthetic crowns is strongly determined by mechanical properties such as elastic stiffness constants, Young's modulus, and shear modulus. YSZ is a highly durable material for dental applications, owing to its superior mechanical strength.

A Comprehensive Ab Initio Study of the Recently Synthesized Zintl Phase CsGaSb2 Structural, Dynamical Stability, Elastic and Thermodynamic Properties

A Comprehensive Ab Initio Study of the Recently Synthesized Zintl Phase CsGaSb2 Structural, Dynamical Stability, Elastic and Thermodynamic Properties

First-principles investigation of the structure and thermodynamic properties of titanium hydrides

The formation of titanium hydrides is closely related to the hydrogen embrittlement in titanium and its alloy. In this work, a comprehensive study on the stable and metastable structures of TiHx (x=0.5, 1, 1.5 and 2) has been performed by means of first-principles calculations in combination with the evolutionary algorithm. The structural features, dynamical stability and elastic properties of these searched titanium hydrides have been systematically investigated. The influence of temperature on the structure stability and phase transition of the Ti2H, TiH, Ti2H3 and TiH2 phases is considered using the quasi-harmonic approximation theory. Our calculations predict that Ti2H, Ti2H3 and TiH2 undergo temperature-driven phase transitions. The reason that the theoretical calculation overestimates the critical temperature of the tetragonal to cubic phase transition in TiH2 within the quasi-harmonic approximations approach is also explored and discussed. The thermodynamic stability of these TiHx (x=0.5, 1, 1.5 and 2) structures is further analyzed over the temperature range of 0–1100 K. TiH2 is the only stable structure in the Ti–H system and Ti2H, TiH, and Ti2H3 are thermodynamically metastable within 900 K.

In silico strategies for identifying therapeutic candidates against Acinetobacter baumannii: spotlight on the UDP-N-acetylmuramoyl-L-alanine-D-glutamate:meso-diaminopimelate ligase (MurE)

The opportunistic bacterium Acinetobacter baumannii, which belongs to ESKAPE group of pathogenic bacteria, is leading cause of infections associated with gram-negative bacteria. Acinetobacter baumannii causes severe diseases, such as VAP (ventilator-associated pneumonia), meningitis, and UTI (urinary tract infections) among the nosocomial infections contracted in hospitals. The high infection rate and growing resistance to the vast array of antibiotics makes it paramount to look for new therapeutic strategies against this pathogen. The most promising therapeutic targets are the proteins involved in the synthesis of peptidoglycan which is chief component of bacterial cell wall, MurE is one of those enzymes and is responsible for the addition of one unit of meso-diaminopimelic acid (meso-A2pm) to the nucleotide precursor, UDPMurNAc-L-Ala-D-Glu, and aids in the formation of crosslinker pentapeptide chain. The three-dimensional structure of MurE was modelled using homology modelling technique and then vHTS was performed using this model against Approved Drug Library on DrugRep server using AutoDock Vina. Out of 500 drug molecules, two were selected based on estimated binding affinity, interaction pattern, interacting residues, etc. The selected drug molecules are DB12887 (Tazemetostat) and DB13879 (Glecaprevir). Then, MD simulations were performed on native MurE and its complexes with ligands to examine their dynamical behaviour, stability, integrity, compactness, and folding properties. The protein-ligand complexes were then subjected to binding free energy calculations using the MM/PBSA-based binding free energy analysis and the values are −109.788 ± 8.03 and −152.753 ± 11.98 kcal for MurE-DB12887 and MurE-DB13879 complex, respectively. All the analysis performed on MD trajectories for the complexes of these ligands with protein provided plenty of dependable evidences to consider these molecules for inhibition of MurE enzyme from A. baumannii. Communicated by Ramaswamy H. Sarma

Mechanical and dynamical stability, electronic, magnetic, and thermoelectric properties of RbBaX (X=Si and Ge) half-Heusler compounds

This research paper explores the structural, electronic, magnetic, elastic, dynamic, and thermoelectric properties of sp-based half-Heusler (HH) RbBaX ([Formula: see text] and Ge) compounds using density functional theory (DFT) and the full-potential linearized augmented plane wave (FP-LAPW) method within the WIEN2k software package. We evaluate the exchange correlation potential using two different approaches: The generalized gradient approximation (GGA) and the modified Becke–Johnson approach. We observe that RbBaX ([Formula: see text] and Ge) adopts a ferromagnetic configuration based on the analysis of total energy against volume. We establish that these alloys possess a genuine half-metallic character because of the full spin polarization observed at the Fermi level in their electronic spectrum. Both compounds under investigation have a total magnetic moment of 1.00[Formula: see text][Formula: see text]B, in agreement with the Slater–Pauling principle. The Born stability criteria for cubic structures and phonon dispersion patterns confirm the mechanical and dynamic stability of RbBaX ([Formula: see text] and Ge) alloys. The thermoelectric properties reveal a p-type semiconductor nature, characterized by significant positive Seebeck values. The thermoelectric figure of merit (ZT) calculated for both alloys at 300[Formula: see text]K approaches unity, highlighting their remarkable thermoelectric efficiency.

Asymmetric XMoGeY2 (X = S, Se, Te; Y = N, P, As) monolayers as potential flexible materials for nano piezoelectric devices and nanomedical sensors.

Highly efficient nano piezoelectric devices and nanomedical sensors are in great demand for high-performance piezoelectric materials. In this work, we propose new asymmetric XMoGeY2 (X = S, Se, Te; Y = N, P, As) monolayers with excellent piezoelectric properties, dynamic stability and flexible elastic properties. The piezoelectric coefficients (d11) of XMoGeY2 monolayers range from 2.92 to 8.19 pm V-1. Among them, TeMoGeAs2 exhibits the highest piezoelectric coefficient (d11 = 8.19 pm V-1), which is 2.2 times higher than that of common 2D piezoelectric materials such as 2H-MoS2 (d11 = 3.73 pm V-1). Furthermore, all XMoGeY2 monolayers demonstrate flexible elastic properties ranging from 96.23 to 253.70 N m-1. Notably, TeMoGeAs2 has a Young's modulus of 96.23 N m-1, which is only one-third of that of graphene (336 N m-1). The significant piezoelectric coefficients of XMoGeY2 monolayers can be attributed to their asymmetric structures and flexible elastic properties. This study provides valuable insights into the potential applications of XMoGeY2 monolayers in nano piezoelectric devices and nanomedical sensors.

Application of density functional theory for evaluating the mechanical properties and structural stability of dental implant materials

BackgroundTitanium is a commonly used material for dental implants owing to its excellent biocompatibility, strength-to-weight ratio, corrosion resistance, lightweight nature, hypoallergenic properties, and ability to promote tissue adhesion. However, alternative materials, such as titanium alloys (Ti–Al-2 V) and zirconia, are available for dental implant applications. This study discusses the application of Density Functional Theory (DFT) in evaluating dental implant materials' mechanical properties and structural stability, with a specific focus on titanium (Ti) metal. It also discusses the electronic band structures, dynamic stability, and surface properties. Furthermore, it presents the mechanical properties of Ti metal, Ti–Al-2 V alloy, and zirconia, including the stiffness matrices, average properties, and elastic moduli. This research comprehensively studies Ti metal's mechanical properties, structural stability, and surface properties for dental implants.MethodsWe used computational techniques, such as the CASTEP code based on DFT, GGA within the PBE scheme for evaluating electronic exchange–correlation energy, and the BFGS minimization scheme for geometry optimization. The results provide insights into the structural properties of Ti, Ti–Al-2 V, and zirconia, including their crystal structures, space groups, and atomic positions. Elastic properties, Fermi surface analysis, and phonon studies were conducted to evaluate the tensile strength, yield strength, ductility, elastic modulus, Poisson's ratio, hardness, fatigue resistance, and corrosion resistance.ResultsThe findings were compared with those of Ti–Al-2 V and zirconia to assess the advantages and limitations of each material for dental implant applications. This study demonstrates the application of DFT in evaluating dental implant materials, focusing on titanium, and provides valuable insights into their mechanical properties, structural stability, and surface characteristics.ConclusionsThe findings of this study contribute to the understanding of dental implant material behavior and aid in the design of improved materials with long-term biocompatibility and stability in the oral environment.

Rapid design and screen high strength U-based high-entropy alloys from first-principles calculations

Reducing the exploration of multi-principal element alloy space is a key challenge to design high-performance U-based high-entropy alloy (UHEA). Here, the best combination of multi-principal element can be efficiently acquired because proposed alloying strategy and screening criteria can substantially reduce the space of alloy and thus accelerate alloy design, rather than enormous random combinations through a trial-and-error approach. To choose the best seed alloy and suitable dopants, the screening criteria include small anisotropy, high specific modulus, high dynamical stability, and high ductility. We therefore find a shortcut to design UHEA from typical binary (UTi and UNb) to ternary (UTiNb), quaternary (UTiNbTa), and quinary (UTiNbTaFe). Finally, we find a best bcc senary UHEA (UTiNbTaFeMo), which has highest hardness and yield strength, while maintains good ductility among all the candidates. Compared to overestimation from empirical strength-hardness relationship, improved strength prediction can be achieved using a parameter-free theory considering volume mismatch and temperature effect on yield strength. This finding indicates that larger volume mismatch corresponds to higher yield strength, agreeing with the available measurements. Moreover, the dynamical stability and mechanical properties of candidates are greatly enhanced with increasing the number of multi-principal element, indicating the feasibility and effectiveness of adopted alloying strategy. The increasing of multi-principal element corresponds to the increasing valence electron concentration (VEC). Alternatively, the mechanical properties significantly improve as increasing VEC, agreeing with measurements for other various bcc HEAs. This work can speed up research and development of advanced UHEA by greatly reducing the space of alloy composition.

Electronic, Thermal and Mechanical Properties of Carbon and Boron Nitride Holey Graphyne Monolayers.

In a recent experimental accomplishment, a two-dimensional holey graphyne semiconducting nanosheet with unusual annulative π-extension has been fabricated. Motivated by the aforementioned advance, herein we theoretically explore the electronic, dynamical stability, thermal and mechanical properties of carbon (C) and boron nitride (BN) holey graphyne (HGY) monolayers. Density functional theory (DFT) results reveal that while the C-HGY monolayer shows an appealing direct gap of 1.00 (0.50) eV according to the HSE06(PBE) functional, the BNHGY monolayer is an indirect insulator with large band gaps of 5.58 (4.20) eV. Furthermore, the elastic modulus (ultimate tensile strength) values of the single-layer C- and BN-HGY are predicted to be 127(41) and 105(29) GPa, respectively. The phononic and thermal properties are further investigated using machine learning interatomic potentials (MLIPs). The predicted phonon spectra confirm the dynamical stability of these novel nanoporous lattices. The room temperature lattice thermal conductivity of the considered monolayers is estimated to be very close, around 14.0 ± 1.5 W/mK. At room temperature, the C-HGY and BN-HGY monolayers are predicted to yield an ultrahigh negative thermal expansion coefficient, by more than one order of magnitude larger than that of the graphene. The presented results reveal decent stability, anomalously low elastic modulus to tensile strength ratio, ultrahigh negative thermal expansion coefficients and moderate lattice thermal conductivity of the semiconducting C-HGY and insulating BN-HGY monolayers.

A first-principles investigation on the structural, stability and mechanical properties of novel Ag, Au and Cu-graphdiyne magnetic semiconducting monolayers

Most recently, silver-metalated graphdiyne (GDY) nanomembranes have been fabricated using the wet-chemistry approach, with highly efficient response for light-driven decomposition of antibiotics (ACS Appl. Nano Mater. 2023, 6, 7395). Inspired by this exciting advance, herein for the first time we theoretically explore the key physical properties of the single-layer M-(N)GDY (M=Cu, Ag, Au) monolayers. Spin-polarized density functional theory (DFT) results reveal that metalated GDY monolayers favor a high-spin ground state, presenting a magnetic moment of 3 µB/unitcell. The sheets are characterized as small band gap magnetic semiconductors, ranging between 0.112 and 0.960 eV, in which only one spin contributes to the band gap. Ab-initio molecular dynamics results confirm the remarkable thermal stability of the constructed graphdiyne nanomembranes at 1000 K. The dynamical stability and mechanical properties at the ground state are furthermore investigated using machine learning interatomic potentials. The ultimate tensile strengths of the metalated graphdiyne lattices are found to be decent, over 6 GPa close to the ground state, but a few folds lower than the native metal-free counterparts. The presented first-principles results confirm remarkable thermal, dynamical and mechanical stability, and appealing electronic characteristics of the metalated graphdiyne nanosheets, attractive to design advanced light-weight energy storage/conversion and spintronic nanosystems.

Dynamic modeling of hard-magnetic soft actuators: Unraveling the role of polymer chain entanglements, crosslinks, and finite extensibility

In recent years, there has been increasing interest in hard-magnetic soft materials (HMSMs) due to their ability to retain high residual magnetization and undergo large deformations under external magnetic loading. The performance of these materials in the dynamic mode of actuation is significantly influenced by internal properties, such as entanglements, crosslinks, and the finite extensibility of polymer chains. This article presents a theoretical framework for modeling the dynamic behavior of a hard-magnetic soft material-based planar actuator. A physics-based nonaffine material model is utilized to consider the inherent properties of polymer chain networks. The governing equation for dynamic motion is derived using Euler–Lagrange’s equation of motion for conservative systems. The devised dynamic model is utilized to examine the dynamic response, stability, periodicity, and resonance properties of a planar hard-magnetic soft actuator for different values of polymer chain entanglements, crosslinks, and finite extensibility parameters. The Poincaré maps and phase-plane plots are presented to analyze the stability and periodicity of the nonlinear vibrations of the actuator. The results reveal that transitions between aperiodic and quasi-periodic oscillations occur when the density of polymer chain entanglements and cross-linking changes. The findings from the present investigation can serve as an initial step towards the design and manufacturing of remotely controlled actuators for various futuristic applications.

The new solid solution of double transition metal MXenes: Atomistic modeling of two-dimensional YScX (X= C and N)

In this paper, the structural and dynamical stability, electronic, optical, and thermodynamic properties of a new solid solution of two transition metals YScX (X = C and N) MXenes have been studied. The calculation is carried out based on density functional theory (DFT) and the pseudopotential technique. The results obtained from the structural, thermodynamical, and dynamical stability have shown that 2D YScC and YScN MXenes are structurally stable and their experimental synthesis is possible. Total density of states and band structure calculations show that YScX (X = C and N) MXene exhibits metallic behavior using LDA, GGA, and GGA + HSE06 approximations. According to the total density of states results, it can be concluded that the YScX MXenes have a pseudogap close to the Fermi level and at the left side, which justifies the structural stability of the studied monolayers. The plots of electron charge density distribution and electron localization function justify the metallic nature of the mentioned structures. The large negative values of the real part of the dielectric function indicate that 2D YScX (X = C and N) MXenes have a metallic Drude-like behavior. The saturation of the surface of 2D monolayers with various F, O, OH, and H functional groups does not change the metallic properties, the only exception that reveals the semiconductor property in the HSE06 method is YScCH2 Mxene where no atomic orbital intersects the Fermi level. In addition, the onset of the absorption spectrum of YScX (X = C and N) MXenes corresponds to zero photon energy, which is a confirmation of the metallic properties of the investigated structures. The GGA + HSE06 method enables faster electromagnetic beam propagation through the 2D materials, particularly in the x-direction of the hexagonal structure, resulting in a lower absorption coefficient and optical conductivity of 2D monolayers compared to the GGA method. The rising trend of entropy with temperature provides evidence for the endothermic behavior of YScC and YScN monolayers. Unlike heat capacity, the Debye temperature of YScX (X = C and N) MXenes decreases with respect to temperature T, according to the inverse relationship between the Debye temperature and the heat capacity. Due to structural and dynamic stability and layered structure with the nature of covalent and metallic bonds, YScX MXenes are a suitable choice for use in electrical connections and as a protective coating with a low friction level.