Hydrostatic Deformation Research Articles

Evolution of H2O content in deforming quartz aggregates: An experimental study

Deformation experiments were carried out on pure quartzite samples (>99% quartz) with a grain size of ∼200 μm from Tana, Northern Norway. Deformation conditions were 900 °C, 0.1 wt% H2O added, strain rate ∼1 × 10−6 s−1 at variable confining pressures from 600 to 2000 MPa. Detailed FTIR measurements of H2O indicate that the H2O content in the grain boundary region is higher than that inside quartz grains. Hydrostatic treatment and deformation at the chosen temperature and pressure conditions lead to further H2O loss from grain interiors and H2O increase in the grain boundary region. Varying the confining pressure does not have an observable effect on the H2O transfer from grains to the grain boundary region. The 3585 cm−1 absorption band increases systematically with increasing confining pressure. As this band is associated with OH in dislocations, the increase may indicate an increased dislocation density with increasing pressure. The triplet of 3317, 3375 and 3438 cm−1 associated with Al-content in quartz increases in the grain boundary region indicating an exchange of H+ together with Al3+ for Si4+. The Al and H exchange suggest dissolution-precipitation processes in the grain boundary region facilitating the movement of the quartz grain boundaries (grain boundary migration). The H2O in the grain boundary region will be important for enhancing grain boundary migration and thus recrystallization processes during deformation.

ЭЛЕКТРОУПРУГИЕ СВОЙСТВА НАЧАЛЬНО-НАПРЯЖЕННОЙ ПЬЕЗОКЕРАМИКИ PZT-4 С ОДНОНАПРАВЛЕННЫМИ ТУННЕЛЬНЫМИ ПОРАМИ

Prediction results and numerical analysis of effect on effective transversal-isotropic electroelastic properties of porous piezoceramics of PZT-4 with unidirectional cylindrical (tunnel) pores of values of its initial axisymmetric stress state are presented. Effective constants have been identified: Young's and shear modules, Poisson's ratio in the transversal plane of isotropy and the "longitudinally/transverse" piezomodule of porous ceramics, which are most significantly influenced by the nature and values of its initial deformation in comparison with other practically "invariant" constants. It has been found that the "transversal" hydrostatic initial deformation of the porous ceramic has a greater effect on the effective constants of the porous ceramic than the same values of the "longitudinal" axial initial deformation.

3D hyoid and tongue kinematics reveal mechanism of tongue base retraction during swallowing in Didelphis virginiana

In anthropoid primates, tongue base retraction (TBR) is a key event for airway protection and bolus propulsion during swallowing. In macaques, hyoid protraction and elevation during swallowing reduce the oral volume and squeeze the tongue base to retract. This novel hyoid-powered hydraulic TBR mechanism implies that the morphology and position of the hyoid are functionally relevant for TBR performance. However, macaque’s highly derived craniofacial and hyoid morphology precludes inference on the evolutionary history and driving mechanism of TBR across mammal phylogeny at large. Here we use biplanar videoradiography and the XROMM workflow to infer TBR mechanism in Didelphis virginiana through high-resolution 3D hyolingual kinematics. Similar to macaques, Didelphis has an incomplete hyoid cornu, which would enable a large hyoid range of motion that facilitates oral volume reduction. Unlike macaques, Didelphis hyoid has a more posteriorly resting hyoid position. We predict that TBR will occur in Didelphis through a similar hyoid-powered hydraulic mechanism. We find Didelphis deploys TBR during the first opening (O1) phase (liquid) or slow-open phase (solid) of jaw cycle with retraction and elevation of midline posterior tongue markers. Minimal retraction occurs in lateral tongue markers where extrinsic lingual muscles insert. The tongue base and posterior tongue are lengthening, narrowing and increasing in height during TBR, consistent with predictions based on muscular hydrostat model. The tongue base was not isovolumetric during TBR, but the volume change was orders of magnitude smaller than that observed in macaques. Hyoid protraction and elevation occur before and continue throughout TBR, which strongly suggest concurrent reduction of oral volume as well. Our preliminary data suggest the TBR mechanism in opossums may differ in important ways from that utilized by macaques, where opossums could employ a combination of hydrostatic deformation and hydraulic mechanism to drive retraction of tongue base. We provide novel insights into the conservation of TBR across therian mammals and extend our understanding on the form-function relationships between the hyolingual apparatus and swallowing biomechanics. Hinds Fund, University of Chicago This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Hydrostatic deformation potentials of narrow-gap HgCdTe

Close to the semimetal-to-semiconductor topological phase transition, the band structure of HgCdTe is represented by massive Kane fermions that, in a semirelativistic approach, are characterized by two parameters: rest mass and velocity. Using terahertz magneto-optical spectroscopy, we explore the band structure evolution of HgCdTe films with hydrostatic pressure in the vicinity of the band-gap collapse. By analyzing the energies of interband optical transitions as a function of magnetic field, we have determined the rest mass of Kane fermions at different hydrostatic pressures. The pressure dependence of the rest mass allows us to obtain the hydrostatic deformation potential ${a}_{c}\ensuremath{-}{a}_{v}$ at low temperature, where ${a}_{c}$ and ${a}_{v}$ are the deformation potentials of the conduction and valence bands, respectively.

A coupled SPH-PD model for fluid–structure interaction in an irregular channel flow considering the structural failure

Understanding fluid–structure interaction (FSI) is important because it dominates diverse natural phenomena and engineering problems. This paper presents an integrated particle model for FSI problems involving irregular channel flows and crack propagation in structures. The proposed model is implemented as follows: (1) we couple weakly compressible smoothed particle hydrodynamics (WCSPH) with bond-based peridynamics (BBPD) in a partitioned approach (this framework has a much simpler algorithm than the previously reported SPH-PD method); (2) we propose a novel periodic boundary conditions (PBCs) algorithm for modeling flows in non-regular channels; and (3) we incorporate crack propagation in structural responses under fluid dynamics, which was rarely considered in previous works. The new framework has been validated and illustrated to be effective and versatile in diverse FSI problems, including hydrostatic pressure-induced solid deformation, violent free-surface flows and channel flows interacting with flexible structures. Compared with conventional grid-based methods, this particle framework is more user-friendly, since no extra effort is required to update meshes, even when a discontinuity appears during the modeling process. The extendibility and potential of this framework is further demonstrated by the simulation of fluid-driven deformation and crack propagation in elastomers.

A generalized Ogden model for the compressibility of rubber-like solids.

The aim of this paper is to further demonstrate the advantages and effectiveness of the constitutive formulation proposed by Huang (Huang 2014 J. Appl. Mech. 59, 902-908 (doi:10.1115/1.2894059)). In this formulation, any strain-energy function for an incompressible material can be easily generalized to include the effect of material compressibility, in which only a few material parameters and material functions to be fitted with the experimental data are required. To this end, the Ogden model for incompressible rubber-like solids is chosen as the starting point. By means of this formulation, the generalized Ogden strain-energy function, which takes into account material compressibility, can conveniently be constructed so long as its incompressible counterpart is given. The obvious advantage shown in this paper is that only a few material parameters and material functions are needed, i.e. in addition to the material parameters used in the original Ogden model for incompressible solids, only one material function depending on the volume ratio is involved to characterize the effect of compressibility. Both the material parameters in the original Ogden model and the material function suggested in this paper can be determined by fitting the experimental data for uniaxially tensile test and hydrostatic deformation test of rubbers, respectively. The present model considering compressibility is general since it can be applied to predict the stress-strain responses of rubber-like materials and porous rubbers in various loading conditions. With the present formulation, the applicable range of the celebrated Ogden model can be further broadened, which should be of practical importance for accurately describing the mechanical behaviour of rubber-like solids. This article is part of the theme issue 'The Ogden model of rubber mechanics: Fifty years of impact on nonlinear elasticity'.

Dynamic compaction of aluminum with nanopores of varied shape: MD simulations and machine-learning-based approximation of deformation behavior

We compare two machine-learning-based approaches, artificial neural network (ANN) and micromechanical model with automatic Bayesian identification of the model parameters, in application to mimicking the deformation behavior of nanoporous aluminum extracted from molecular dynamics (MD) simulations. Reference data are generated by means of MD simulation of both hydrostatic and uniaxial deformation with compression of representative volume elements of aluminum single crystal with nanopores of spherical, cubic and cylindrical shapes at the temperatures of 300, 500, 700 and 900 K. Several typical sizes of the nanopores are considered: The smallest one corresponds to the initial porosity less than 1%, while the largest one gives the initial porosity in the range of 30–50%. Plastic collapse of nanopores in all cases occurred by the mechanism of emission of partial Shockley dislocation half-loops from the pore surface. The emission of initial loop occurred earlier in the case of cylindrical pore; however, this did not lead to an explosive increase in the number of dislocations in the system at this stage. In general, flat free surfaces of pores are less subjected to the dislocation nucleation than the rounded ones. A new physically-based micromechanical model of the plastic compaction of nanoporous metal is formulated with accounting of different pore shapes and anisotropy of the compaction process. Both tested machine-learning approaches show an adequate approximation of MD data. The developed ANN and parameterized micromechanical model are applied to simulate the propagation of a shock wave in nanoporous aluminum in comparison with direct MD simulations of this process; this comparison shows an adequate description of the shock wave structure by means of both approaches incorporated into continuum mechanics modeling. Thus, the developed machine-learning-based approaches can be applied as constitutive equations of nanoporous aluminum in macroscopic simulations of the dynamic compaction and shock-wave processes in this material.

Hyperelastic behaviors of closed-cell porous materials at a wide porosity range

In this paper, the constitutive model proposed in the previous work for neo-Hookean materials with spherical voids and an explicit homogenization solution named Shrimali-Lefèvre-Lopez (SLL) model for isotropic porous elastomers are adopted to theoretically predict the macroscopic effective hyperelastic responses of the closed-cell porous materials with rubber-like incompressible neo-Hookean matrix at finite deformations. Representative volume element (RVE) models with randomly distributed non-overlapping polyhedral voids are employed to numerically validate the theoretical models at a wide porosity range from 0.05 to 0.9. Various deformations including hydrostatic deformations, pure shear deformations, uniaxial deformations and plane strain deformations are applied to the theoretical and RVE models. The results show that the theoretical models can well estimate the effective hyperelastic properties of the porous materials under all deformation conditions considered, and our theoretical model is complementary with the SLL model for predicting different effective properties under given deformation. The constitutive models are also validated experimentally by comparing with the experimental data from the literature.

Biomechanical Analysis of the Ross Procedure in an Ex Vivo Left Heart Simulator.

Neo-aortic pulmonary autografts often experience root dilation and valve regurgitation over time. This study seeks to understand the biomechanical differences between aortic and neo-aortic pulmonary roots using a heart simulator. Porcine aortic, neo-aortic pulmonary, and pulmonary roots (n = 6) were mounted in a heart simulator (parameters: 100 mm Hg, 37 °C, 70 cycles per minute, 5.0 L/min cardiac output). Echocardiography was used to study root distensibility (percentage change in luminal diameter between systole and diastole) and valve function. Leaflet motion was tracked with high-speed videography. After 30 min in the simulator, leaflet thickness (via cryosectioning), and multiaxial modulus (via lenticular hydrostatic deformation testing) were obtained. There were no significant differences between aortic and neo-aortic pulmonary leaflet motion, including mean opening velocity (218 vs 248 mm/s, P = .27) or mean closing velocity (116 vs 157 mm/s, P = .12). Distensibility was similar between aortic (8.5%, 1.56 mm) and neo-aortic pulmonary (7.8%, 1.12 mm) roots (P = .59). Compared to virgin controls, native pulmonic roots exposed to systemic pressure for 30 min had reduced leaflet thickness (630 vs 385 µm, P = .049) and a reduced Young's modulus (3,125 vs 1,089 kPa, P = .077). In contrast, the aortic roots exposed to pressure displayed no significant difference in aortic leaflet thickness (1,317 vs 1,256 µm, P = .27) or modulus (5,931 vs 3,631 kPa, P = .56). Neo-aortic pulmonary roots demonstrated equivalence in valve function and distensibility but did experience changes in biomechanical properties and morphology. These changes may contribute to long-term complications associated with the Ross procedure.

A link between mechanical heterogeneity and nontrivial local structural power-law response in a model metallic glass

The structural heterogeneity and mechanical inhomogeneity of metallic glasses at the nanoscale have been demonstrated by extensive experimental investigations, while their inherent correlation remains ambiguous. Based on elasticity theory, a model is developed to describe the local structural response of metallic glasses under hydrostatic deformation. We establish a linear relationship between the local bulk modulus and the nontrivial power-law exponent of the structural response and further verify this relationship by molecular dynamics simulations. The intrinsic link between the local structural response and elastic modulus reveals that the mechanical heterogeneity reflects not only the static atomic packing but also the dynamic evolution of the amorphous structure. Our findings provide direct evidence that mechanical heterogeneity is a feasible indicator for describing the structural heterogeneity of metallic glasses and shed some light on the non-cubic structural power law of disordered materials.

STATIC STABILITY OF AERODYNAMICALLY SUPPORTED PLATFORMS MOVING ABOVE WATER

The motion stability is the most important problem of high-speed marine vehicles that utilize aerodynamic support. A simplified analysis and calculations of longitudinal static stability of several basic platforms moving above water are carried out in this study. The analysis is based on the extreme ground effect theory and the assumption of hydrostatic deformations of the water surface. Effects of the underlying surface type, Froude number, and several geometrical parameters on main aerodynamic characteristics, including the static stability margin, are presented. If the underlying surface is water instead of a rigid plane, the static stability worsens for platforms with flat or S-shaped lower surfaces, but it slightly improves for a horizontal platform with a flap. The static stability margin remains positive for S-shaped profiles at sufficiently low Froude numbers, while it is negative for other configurations.

The Lunar Fossil Figure in a Cassini State

Abstract The present ellipsoidal figure of the Moon requires a deformation that is significantly larger than the hydrostatic deformation in response to the present rotational and tidal potentials. This has long been explained as due to a fossil rotational and tidal deformation from a time when the Moon was closer to Earth. Previous studies constraining the orbital parameters at the time the fossil deformation was established find that high orbit eccentricities (e ≳ 0.2) are required at this ancient time, which is difficult to reconcile with the freezing of a fossil figure owing to the expected large tidal heating. We extend previous fossil deformation studies in several ways. First, we consider the effect of removing South Pole−Aitken (SPA) contributions from the present observed deformation using a nonaxially symmetric SPA model. Second, we use the assumption of an equilibrium Cassini state as an additional constraint, which allows us to consider the fossil deformation due to nonzero obliquity self-consistently. A fossil deformation established during Cassini state 1, 2, or 4 is consistent with the SPA-corrected present deformation. However, a fossil deformation established during Cassini state 2 or 4 requires large obliquity and orbit eccentricity (ϵ ∼ 68° and e ∼ 0.65), which are difficult to reconcile with the corresponding strong tidal heating. The most likely explanation is a fossil deformation established during Cassini state 1, with a small obliquity (ϵ ∼ −0.2°) and an orbit eccentricity range that includes zero eccentricity (0 ≤ e ≲ 0.3).

A model for irreversible deformation phenomena driven by hydrostatic stress, deviatoric stress and an externally applied field

Hydrostatic, deviatoric, and external field-driven irreversible dissipations have generally been modeled by separated models. However, since all the irreversible dissipations are governed by the laws of thermodynamics, it is possible to describe the coupled multi-irreversible dissipations with a general model. This paper presents a modeling structure of inelastic potential for coupled multi-irreversible dissipation conditions based on the thermodynamic laws. The inelastic potential is derived from a proposed inelastic dissipation function, and the scalar rates of irreversible deformation are formulated to consider the coupled effect of irreversible hydrostatic deformation, deviatoric deformation, and field-driven internal response. In this paper, the inelastic potential model is discussed with visualized potential surfaces, and some numerical examples are conducted to test the model in several conditions. In addition, the model is applied to three practical engineering problems. The results of this paper show that this model can be used as a general model to simulate individual irreversible dissipation as well as the coupled multi-irreversible phenomena.

Oscillatory thermocapillary convection in deformed half zone liquid bridges of low Prandtl number fluids

A series of three-dimensional (3D) transient simulations are carried out to study the onset and features of oscillatory thermocapillary convection in deformed half zone liquid bridges of low Prandtl number fluids (Pr = 0.01) with unit aspect ratio (As). The critical conditions for different volume ratios on ground and under microgravity are determined. It turns out that the threshold of the second bifurcation is more sensitive to volume ratio than the first bifurcation. The thresholds in deformed liquid bridges are usually higher than those in cylindrical liquid bridges. The critical azimuthal wavenumber increases from 2 to 3 with volume ratio. Gravity affects the flow through three factors. Compared with the hydrostatic deformation and heating orientation, buoyancy is marginal to the flow transition. It only affects the threshold and the deviation caused by buoyancy is within 2%. The effects of gravity on the critical conditions are dependent on volume ratio. Except for the threshold, gravity may also affect the critical azimuthal wavenumber and the critical oscillation mode. 3D oscillatory flow regimes with two different oscillation modes are present. A new type of “Rocking” mode is discovered in the present study.

Electronic, elastic, and topological behavior of MgH2, MgTiH4, and TiH2 under pressure

This paper studies the elastic, structural, electronic, and topological behaviors of α-MgH2, β-MgH2, MgTiH4, and TiH2 under pressure by resorting to DFT-GGA’s first principle via FPLAPW-WIEN2K, ElaStic1.0, and Critic2 software. Pressure effects are studied from strain vectors generating a linear volume variation with strain. Important structural changes by the effect of pressure are evidenced. The highest strength at hydrostatic deformation was reached by TiH2; and the lowest, by α-MgH2. The elastic constants and moduli for each hydride studied showed agreement with the results reported in the literature. The TiH2 cubic lattice is shown to be structurally unstable. Hydrides showed more stability than pure crystals. The tetragonal structure of MgH2 was confirmed as more stable than its respective cubic structure; and the cubic structure of TiH2, even more so than that of the Mg hydrides, independently of their crystalline structure. Hydrides with a cubic structure showed a ductile condition, whereas those with a tetragonal structure showed a fragile one. α-MgH2 revealed an insulating character. Other hydrides studied showed a conductive character. The topology of charge density and potential energy density establishes a marked difference between the topological classes and the number of critical points (CPs) for both cubic (β-MgH2, TiH2) and tetragonal structures (α-MgH2, MgTiH4), the multiplicity of these being markedly superior in the former. The bonding character in general is covalent in the CP nucleus and both closed-layered and hydrogen-bonded in the other CPs, except in the Ti-H CP bond of the compressed structures, which bears an ionic character, unlike that of expanded structures. The incorporation of Ti to MgH2 weakens the Mg-H bond, which in turn favors the kinetics of dehydrogenation in MgTiH4.

Free Vibration of Rubber Matrix Cord-Reinforced Combined Shells of Revolution Under Hydrostatic Pressure

Abstract In this paper, the free vibration of rubber matrix cord-reinforced combined shells of revolution under hydrostatic pressure is investigated by the precise transfer matrix method. Under hydrostatic pressure, deformation and stress are generated in the rubber matrix composite shell. Based on the deformation characteristics of the rope structure, the deformation of the shell under hydrostatic pressure is analyzed. The stress of the shell under hydrostatic pressure is included in the shell differential equation of motion in the form of pre-stress. Then considering the fluid-solid coupling boundary condition, the field transfer matrix of the fluid-filled spherical shell is obtained. By the continuous condition of the state vector of the shell and the transformation relationship of the coordinate system, the transfer matrices at the position of the ring-stiffener and the connection position of the cylindrical shell and spherical shell are derived, and then the whole free vibration equation of the fluid-filled combined shells of revolution is assembled, and the natural frequencies are obtained by the boundary conditions. Eventually, the accuracy and reliability of the proposed method are verified by the results of literature and simulation results. Effects of the structural parameters of the spherical shell, the distribution of the ring-stiffeners, and the hydrostatic pressure on the natural frequencies of the fluid-filled combined shells of revolution are also discussed. Results of this paper can provide reference data for future studies in the related field.

Constitutive modeling for linear viscoelastic fiber-reinforced composites

In this paper, a micromechanics-based constitutive model is proposed for linear viscoelastic fiber-reinforced composites via a homogenization procedure in the time domain. Based on an additive decomposition, a general deformation is split into four simple deformations, namely, longitudinal tension/compression, transversely hydrostatic deformation, along-fiber shear and transverse shear. For each simple deformation, the mechanical response of the composite is reformulated utilizing the effective time-dependent relaxation functions and the effective referred elastic (time-independent) stresses, which are computed based on micromechanics. The constitutive equations for the linear viscoelastic fiber-reinforced composites are then derived through superposing the effective stresses for all the four simple deformations. The constitutive model has a simple form, which facilitates to study the effective mechanical behaviors of the composites in both the time and frequency domains. The representative volume element (RVE) models with different fiber volume fractions are created to simulate the effective viscoelastic behaviors of the fiber-reinforced composites. The comprehensive numerical simulation results reveal that the constitutive model can offer quite consistent effective mechanical responses with the finite element simulations. The experimental results in the literature are also employed to validate the constitutive model, and the findings show that the constitutive model can offer satisfactory prediction accuracy.

Indium Gallium Oxide Alloys: Electronic Structure, Optical Gap, Surface Space Charge, and Chemical Trends within Common-Cation Semiconductors.

The electronic and optical properties of (InxGa1-x)2O3 alloys are highly tunable, giving rise to a myriad of applications including transparent conductors, transparent electronics, and solar-blind ultraviolet photodetectors. Here, we investigate these properties for a high quality pulsed laser deposited film which possesses a lateral cation composition gradient (0.01 ≤ x ≤ 0.82) and three crystallographic phases (monoclinic, hexagonal, and bixbyite). The optical gaps over this composition range are determined, and only a weak optical gap bowing is found (b = 0.36 eV). The valence band edge evolution along with the change in the fundamental band gap over the composition gradient enables the surface space-charge properties to be probed. This is an important property when considering metal contact formation and heterojunctions for devices. A transition from surface electron accumulation to depletion occurs at x ∼ 0.35 as the film goes from the bixbyite In2O3 phase to the monoclinic β-Ga2O3 phase. The electronic structure of the different phases is investigated by using density functional theory calculations and compared to the valence band X-ray photoemission spectra. Finally, the properties of these alloys, such as the n-type dopability of In2O3 and use of Ga2O3 as a solar-blind UV detector, are understood with respect to other common-cation compound semiconductors in terms of simple chemical trends of the band edge positions and the hydrostatic volume deformation potential.

Hybrid hydraulic‐seasonal‐time model for predicting the deformation behaviour of high concrete dams during the operational period

Considering the limitations of the traditional hydraulic-seasonal-time (HST) model, this study proposes a hybrid modeling method for the deformation prediction of high concrete dams during the operational period. First, the elastic finite element (FE) method is applied to simulate the interactive effects of structural properties, topography, geology, and high hydrostatic load on the deformation behaviour of high concrete dams in operating conditions. The hybrid model of hydrostatic pressure deformation is established. The hybrid hydraulic-seasonal-time (HHST) model is proposed. Second, the self-adaptive stochastic inertia weight, dynamic learning factors, and velocity and position parameters are introduced to improve the particle swarm optimization (PSO) algorithm. The hybrid prediction approach is developed through the comprehensive application of the HHST model and the improved PSO algorithm. The proposed methodology is adopted for the Jinping I project, which is the highest concrete arch dam in the world. The analysis results indicate that the model accuracy is good and that the model performance is promoted.

The functional morphology of lingual prey capture in a scincid lizard, Tiliqua scincoides (Reptilia: Squamata).

We investigated the functional morphology of lingual prey capture in the blue-tongued skink, Tiliqua scincoides, a lingual-feeding lizard nested deep within the family Scincidae, which is presumed to be dominated by jaw-feeding. We used kinematic analysis of high-speed video to characterize jaw and tongue movements during prey capture. Phylogenetically informed principal components analysis of tongue morphology showed that, compared to jaw-feeding scincids and lacertids, T. scincoides and another tongue-feeding scincid, Corucia zebrata, are distinct in ways suggesting an enhanced ability for hydrostatic shape change. Lingual feeding kinematics show substantial quantitative and qualitative variation among T. scincoides individuals. High-speed video analysis showed that T. scincoides uses significant hydrostatic elongation and deformation during protrusion, tongue-prey contact, and retraction. A key feature of lingual prey capture in T. scincoides is extensive hydrostatic deformation to increase the area of tongue-prey contact, presumably to maximize wet adhesion of the prey item. Adhesion is mechanically reinforced during tongue retraction through formation of a distinctive "saddle" in the foretongue that supports the prey item, reducing the risk of prey loss during retraction.