Changes In Elastic Properties Research Articles

A rock physics modelling approach for time‐lapse monitoring and characterization of fluid–rock interactions in hydrocarbon reservoirs

AbstractOne of the research gaps is to understand the development of seismic characteristics of gas‐saturated rock along with the change in rock properties because of chemical reactions. We suggest a method to explain the change in elastic properties brought on by CO2 injection in a rock by capturing the physico‐chemical interactions observed in the laboratory in a theory of rock physics. To explain the laboratory‐measured physical characteristics and velocity of a dynamic rock–fluid system, we include a time‐dependent component in the existing cemented‐sand model. We demonstrate theoretically the rate of change of elastic moduli of the dry frame by incorporating the measured rate of change of cement due to chemical dissolution. We adapt the theory such that it can be applied to the field data and calibrate the theory using water‐saturated well log data from the Ankleshwar field, an established oil field in the Cambay basin, western India. Theoretical time‐lapse logs of velocity and density are then produced using the theory over a range of CO2 saturations, assuming cementing material in grain contacts and geochemical interactions comparable to those observed in the laboratory rock. Then, using theoretical logs, corresponding time‐lapse synthetic seismic data are produced for different saturation. These data clearly demonstrate that, for a uniform model, velocity decreases by up to 18% as CO2 saturation increases from 0% to 20% (ignoring the chemical effect), and that, for a specific saturation, say 20%, chemical effects result in a 17% decrease in velocity from the present to the end of 60 years. However, for the patchy model, velocity decreases maximum by 14% and 16% due to varying saturation and chemical reaction. Moreover, for a particular saturation of CO2, say 20%, velocity differs by 16% for different types of models. This research contributes to making strategy for CO2‐sequestration in a designated field.

Aortic aneurysm: Correlations with phenotypes associated with connective tissue dysplasia

An aortic aneurysm is a localized enlargement that exceeds the normal diameter of the vessel by 50 %, posing a risk due to the likelihood of rupture. The cause of aortic aneurysm, especially in young people, is connective tissue dysplasia, a condition characterized by defects in the assembly of collagen and elastin proteins, leading to changes in elastic properties and disruption of the formation of organs and their systems. The article presents data confirming the relationship between many morphological manifestations of connective tissue dysplasia (e.g., funnel-shaped deformation of the sternum, scoliosis of the thoracic spine, abdominal hernias, arterial tortuosity, striae of atypical localization) and the risk of aortic aneurysm formation. The literature suggests that the identified combinations of some external manifestations of connective tissue dysplasia deserve special attention and may be constitutional markers for the possible development of aortic aneurysm, which is a promising direction for further research in this area.

Exploring changes in structural, electronic and elastic properties of TiO2 under pressure: A DFT investigation

Titanium dioxide (TiO2) is a semiconductor material that widely used in numerous applications due to its exceptional physical and chemical properties. This study explores the structural, electronic and elastic properties of TiO2 phases in rutile, anatase and brookite under hydrostatic pressure up to 100 GPa. At 0 GPa, the computed lattice parameters and volumes align closely with experimental data. The band structure reveals that rutile and brookite exhibit direct band gaps while anatase shows an indirect band gap. Elastic properties including bulk modulus, shear modulus, Young’s modulus, Cauchy pressure, Pugh ratio and Poisson’s ratio were calculated using the Voigt-Reuss-Hill approximation. Our findings confirm the mechanical stability of all TiO2 phases and offer insights that align with existing theoretical and experimental data. These findings provide a comprehensive understanding of behavior of TiO2 under high-pressure condition which is crucial for optimizing its applications in various fields such as photocatalysis and solar cells.

Local strain heterogeneity associated with Al/Si ordering in anorthite, CaAl2Si2O8, with implications for thermodynamic mixing behavior and trace element partitioning in plagioclase feldspars

Abstract Hard Mode IR powder absorption spectroscopy has been used to characterize local strain relaxation associated with Al/Si ordering in a suite of synthetic anorthite samples with structural states that vary from a high degree of Al/Si order through a metastable incommensurate structure at intermediate states of order to long-range order with I1 symmetry. The dominant feature accompanying the changing structural states is line broadening, which has been quantified by autocorrelation analysis and is attributed to local heterogeneous strain variations on a length scale of at least 1–5 unit cells. The autocorrelation results are consistent with contributions to the line broadening as being due to order parameters for both the C1 → I1 and I1 → P1 transitions, which couple biquadratically, λQod2Qdispl2. Close correlation with enthalpy variations from previously published calorimetric data indicates that the driving force for ordering can be understood in terms of elimination of strain fields arising from accommodating more or less rigid AlO4 and SiO4 tetrahedra in the feldspar framework. The metastable incommensurate structure of anorthite is closely analogous to the stable incommensurate structure that develops at intermediate compositions in the plagioclase solid solution, confirming that the same strain relaxation mechanism dominates the properties and behavior of all structural states across the solid solution. Elimination of strain heterogeneity by ordering on the basis of I1 symmetry determines the form of non-ideal mixing shown by the solid solution at high temperatures, and changes in elastic properties may contribute to a break in the slope of partitioning of trace elements between crystals and melt.

Hydrogen bond symmetrisation in D2O ice observed by neutron diffraction

Hydrogen bond symmetrisation is the phenomenon where a hydrogen atom is located at the centre of a hydrogen bond. Theoretical studies predict that hydrogen bonds in ice VII eventually undergo symmetrisation upon increasing pressure, involving nuclear quantum effect with significant isotope effect and drastic changes in the elastic properties through several intermediate states with varying hydrogen distribution. Despite numerous experimental studies conducted, the location of hydrogen and hence the transition pressures reported up to date remain inconsistent. Here we report the atomic distribution of deuterium in D2O ice using neutron diffraction above 100 GPa and observe the transition from a bimodal to a unimodal distribution of deuterium at around 80 GPa. At the transition pressure, a significant narrowing of the peak widths of 110 is also observed, attributed to the structural relaxation by the change of elastic properties.

CO2 rock physics modeling for reliable monitoring of geologic carbon storage

Monitoring, verification, and accounting (MVA) are crucial to ensure safe and long-term geologic carbon storage. Seismic monitoring is a key MVA technique that utilizes seismic data to infer elastic properties of CO2-saturated rocks. Reliable accounting of CO2 in subsurface storage reservoirs and potential leakage zones requires an accurate rock physics model. However, the widely used CO2 rock physics model based on the conventional Biot-Gassmann equation can substantially underestimate the influence of CO2 saturation on seismic waves, leading to inaccurate accounting. We develop an accurate CO2 rock physics model by accounting for both effects of the stress dependence of seismic velocities in porous rocks and CO2 weakening on the rock framework. We validate our CO2 rock physics model using the Kimberlina-1.2 model (a previously proposed geologic carbon storage site in California) and create time-lapse elastic property models with our new rock physics method. We compare the results with those obtained using the conventional Biot-Gassmann equation. Our innovative approach produces larger changes in elastic properties than the Biot-Gassmann results. Using our CO2 rock physics model can replicate shear-wave speed reductions observed in the laboratory. Our rock physics model enhances the accuracy of time-lapse elastic-wave modeling and enables reliable CO2 accounting using seismic monitoring.

Computational systematic study of pressure driven changes in electronic, optical, elastic, mechanical, thermodynamic and thermoelectric properties of CaZrO3 for optoelectronic and thermoelectric applications

Calcium Zirconate Oxide (CaZrO3) was studied in this work for its electronic, optical, structural, thermoelectric and thermodynamic properties in the consistent external pressure from 0 to 100 GPa. The correlation functionals utilized have been Generalized Gradient Approximations (GGA) and Heyd-Scuseria-Ernzerhof (HSE03). The structure maintains its cubical structure for a maximum of 100 GPa, while the lattice parameters gradually decrease when exposed to external pressure. Band structure are seen an indirect band at 0–40 GPa whereas direct band at 60–100 GPa (4.737–4.629 eV). To further comprehend the band gap, decrease with the estimated partial densities of states (PDOS) for bulk CaZrO3 for Ca, Zr and O are also estimated. Optical properties such as absorption I(ω), complex optical conductivity σ (ω), complex dielectric function ε(ω), loss function L(ω), reflectivity R(ω) and complex refractive index n(ω) varies significantly with external pressure ranges from 0 to 100 GPa. Mechanical stability is only observed at pressures up to 0–100 GPa becomes stable according to elastic constants. According to Pugh's ratio, the compound is ductile at 0–100 GPa. Whereas Poisson ratio shows metallic bonding up to 100 GPa, our predicted findings show anisotropic nature. According to the thermoelectric properties, these phases could potentially beneficial for thermoelectric devices. Thermodynamic parameters with respect to both temperature and pressure, including heat capacity, thermal expansion, and Debye temperature, from 0 to 1000 K and 0–100 GPa. CZO has phonon density of states and dispersion are calculated along high symmetry directions. This structure is dynamically stable and all frequencies are in the positive phonon spectrum.

The Effect of Cesium Incorporation on the Vibrational and Elastic Properties of Methylammonium Lead Chloride Perovskite Single Crystals.

Hybrid organic-inorganic lead halide perovskites (LHPs) have emerged as a highly significant class of materials due to their tunable and adaptable properties, which make them suitable for a wide range of applications. One of the strategies for tuning and optimizing LHP-based devices is the substitution of cations and/or anions in LHPs. The impact of Cs substitution at the A site on the structural, vibrational, and elastic properties of MAxCs1-xPbCl3-mixed single crystals was investigated using X-ray diffraction (XRD) and Raman and Brillouin light scattering techniques. The XRD results confirmed the successful synthesis of impurity-free single crystals, which exhibited a phase coexistence of dominant cubic and minor orthorhombic symmetries. Raman spectroscopy was used to analyze the vibrational modes associated with the PbCl6 octahedra and the A-site cation movements, thereby revealing the influence of cesium incorporation on the lattice dynamics. Brillouin spectroscopy was employed to investigate the changes in elastic properties resulting from the Cs substitution. The incorporation of Cs cations induced lattice distortions within the inorganic framework, disrupting the hydrogen bonding between the MA cations and PbCl6 octahedra, which in turn affected the elastic constants and the sound velocities. The substitution of the MA cations with smaller Cs cations resulted in a stiffer lattice structure, with the two elastic constants increasing up to a Cs content of 30%. The current findings facilitate a fundamental understanding of mixed lead chloride perovskite materials, providing valuable insights into their structural and vibrational properties.

Non-destructive degradation assessment of GFRP beams subjected to hygrothermal ageing

This work used free vibration tests based on impulse excitation technique and experimental modal analysis using an impact hammer and an accelerometer to assess the local and global effects of the hygrothermal ageing of GFRP specimens exposed to salt-spray environment at 35°C and 60°C over a period of 136 days. Through the change in elastic properties, fifteen natural frequencies and damping ratios, the effects of degradation are associated with reductions in elastic properties and natural frequencies and an increase in damping ratios. In turn, the increase in elastic properties and natural frequencies – associated with a reduction in damping ratios – is mainly attributed to the post-curing effect.

Effect of impurities on elastic properties and grain boundary strength of vanadium：A first principles study

During the processing of vanadium, the inevitable incorporation of impurities can exert a significant influence on the mechanical properties. In this work, the effects of common impurity elements (H, C, N, O, Al, Cr and Fe) on elastic properties and V ∑3(111) grain boundary strength were studied by first-principles calculations. The results show that the H, C, N, O and Al elements can improve the deformation resistance but reduce the ductility of vanadium, whereas Fe exhibit the opposite effect. Electronic structure analysis provided a reasonable explanation for the observed changes in elastic properties. Then, first-principles-based tensile tests were carried out on vanadium grain boundary with impurities. The findings demonstrate that C enhances the tensile strength of vanadium grain boundary by improving the weakest bonds between adjacent V atoms. Conversely, the detrimental effect of O was attributed to the reduction of interaction between V atoms. This study contributes to a better knowledge of the potential positive and negative impacts of impurities on the mechanical properties of vanadium and provides valuable insights for future research in materials processing.

Effect of degradation in polymer scaffolds on mechanical properties: Surface vs. bulk erosion

Porous polymeric scaffolds are used in tissue engineering to maintain or replace damaged biological tissues. Once embedded in body, they are involved into different physical and biological processes, among which their degradation and dissolution of their material can be singled out as one of the most important ones. Degradation parameters depend mostly on the properties of both the material and surrounding native tissues, which can substantially alter the original mechanical parameters of the scaffolds. The aim of this study is to examine the change in the effective mechanical properties of functionally graded additively manufactured polylactide scaffolds with a linear porosity gradient and morphology based on triply periodic minimal surfaces during simultaneous degradation and compressive loading. Two main types of scaffold-degradation processes, bulk and surface erosions are simulated with two suggested modelling methods. The fundamental differences in the proposed approaches are identified and the influence of different types of scaffold morphology on the change in effective elastic properties is evaluated. The results of this study can be useful for design of optimal scaffolds taking into account the effect of the degradation process on their structural integrity.

Random processes in modeling durability of building and structure

The problem of buildings and structures durability during their long-term operation in aggressive environments is discussed. It is closely connected with the problem of destruction of composite materials as a random process of birth, development, and death of defects at chemical corrosion. The content of the study is to analyze the influence of non-stationary chemical reactions occurring in real conditions on these processes. The analysis is carried out taking into account the incidental physical phenomena affecting corrosion, the most important of which is the diffusion of initial substances and reaction products occurring under different hydrodynamic conditions, i.e., the nature of fluid motion and its pressure which stimulates corrosion. The synthesis of three processes – chemical kinetics, diffusion, and hydrodynamics – allows us to study one of the possible scenarios of corrosion process development as a Markov process based on the statistical theory of the “weakest” link and the joint distribution of the random material and geometric parameters. Numerical analysis of changes in elastic and electrical properties of composite materials under these conditions allows us to substantiate the technology of non-destructive control of changes in the state of the structure. The research results are based on mathematical and statistical modeling.

P‐Wave Velocities Across the α → β Quartz Transition at Lower Continental Crust Pressure and Temperature Conditions

AbstractThe quartz α → β transition is a displacive phase transition associated with a significant change in elastic properties. However, the elastic properties of quartz at high‐pressure and temperature remain poorly constrained experimentally, particularly within the field of β‐quartz. Here, we conducted an experimental study on the quartz α → β transition during which P‐wave velocities were measured in‐situ at pressure (from 0.5 to 1.25 GPa) and temperature (200–900°C) conditions of the continental lower crust. Experiments were carried out on samples of microcrystalline material (grain size of 3–6 μm) and single‐crystals. In all these, the transition was observed as a minimum in P‐wave velocities, preceded by an important softening while P‐wave velocities measured in the β‐quartz field were systematically lower than that predicted by thermodynamic databases. Additional experiments during which acoustic emission (AE) were monitored showed no significant peak of AEs near or at the transition temperature. Microstructural analysis nevertheless revealed the importance of microcracking while Electron Back‐Scatter Diffraction (EBSD) imaging on polycrystalline samples revealed a prevalence of Dauphiné twinning in samples that underwent the transition. Our results suggest that the velocity change due to the transition known at low pressure might be less important at higher pressure, implying a change in the relative compressibilities of α and β quartz. If true, the velocity changes related to the α → β quartz transition at lower crustal conditions might be lower than that expected in thickened continental crust.

Sanding phenomena vulnerability observations due to CO2 injection at the Air Benakat reservoir in South Sumatera

Carbon sequestration using carbon capture storage (CCS) is one of the most important operational activities in the oil and gas industry to reduce greenhouse gas emissions and increase hydrocarbon production. Carbon Capture Utilization & Storage (CCUS) can be utilized for both enhancing oil recovery (CO2-EOR), as well as gas recovery (CO2-EGR) by injecting CO2 into the reservoir. However, the CO2 injection into reservoir rock can raise potential sanding problems in both injection and production wells. The phenomena of sanding may be induced dominantly due to carbonic acid injection in the reservoir. The reaction between CO2 and water will form carbonic acid in the reservoir, which can cause the dissolution of rock minerals, especially carbonate cementation (such as calcite and dolomite). We have investigated the sanding effect when CO2 was injected into the reservoir using several laboratory-scale measurements and observations on the Air Benakat reservoir sample in South Sumatera. The sanding vulnerability was measured by observing pore structure, changes in elastic properties, and rock strength through Rock Physics and Rock Mechanics measurements. XRD analysis showed the presence of CaMg(CO3)2 (dolomite) minerals in the Air Benakat sandstone sample, which resulted in the possibility of a chemical reaction of the sample, either matrix or pores. The pore structure dissolution was detected from microscale images when the rock was injected with CO2 dissolved in brine water. The changes in rock’s pores due to the dissolution process were also clearly observed from measurements of the changes in rock mass during the injection process of carbonic acid fluid into rock samples from time-to-time measurement.

Using resonant ultrasound spectroscopy to characterize thermally conditioned high explosive materials

The ability to nondestructively quantify changes in mechanical properties of granular high explosive materials due to thermal conditioning is of importance for a myriad of civil and defense applications and could lead to better understanding of environmental aging-related effects for explosive material performance and safety. In this study, we report the first demonstration of using resonant ultrasound spectroscopy (RUS) to quantify the bulk elastic properties of granular high explosive materials at different bulk pressing densities and degree of thermal conditioning. Monitoring elastic property changes in granular explosive pressings has not yet been demonstrated using RUS, which is an appealing nondestructive characterization tool since it requires only dry point contact with the explosive material and can be applied to explosives with small form factors. Here, explosive material was studied in the form of binderized plastic bonded explosive pressings and unbinderized neat pressings, both of which are used commercially. Elastic stiffness coefficients calculated from the RUS measurements on the binderized and neat pressings show a significant increase for the post-conditioned samples compared to the pre-conditioned samples. This trend of increasing elastic properties with thermal conditioning was consistent for different density pressings and different thermal exposure conditions. [This work was performed by LLNL under Contract No. DE-AC52-07NA27344 and document release number LLNL-ABS-858868.]

Demonstrating resonant ultrasound spectroscopy as a viable technique to characterize thermally conditioned high explosive materials

We present results of resonant ultrasound spectroscopy (RUS) measurements applied to granular high explosive materials at different bulk pressing densities and degree of thermal conditioning. The material chosen in this study is a ubiquitously used explosive material known as pentaerythritol tetranitrate (PETN), which is used commercially in civil and defense applications both as a binderized plastic bonded explosive material and an unbinderized neat material. However, changes in granular PETN bulk elastic properties due to thermal conditioning, which could have implications for better understanding environmental aging-related effects, have not been well studied even though it is believed that elasticity may play an important role in explosive material initiation mechanisms. Furthermore, monitoring elastic property changes in granular explosive pressings has not yet been demonstrated using RUS, which is an appealing non-destructive characterization tool that requires only dry point contact with the explosive material. To this end, we report the first study using RUS to quantify the elastic properties of binderized and neat PETN pressings as well as to quantify changes in elastic properties as a function of both thermal conditioning and bulk pressing density. Elastic stiffness coefficients, sometimes more commonly referred to as elastic constants, calculated from the RUS measurements on the different PETN-based materials show a significant increase for the post-conditioned samples compared to the pre-conditioned samples. This trend of increasing elastic properties with thermal conditioning was consistent for different density pressings, different thermal exposure conditions, and even different neat PETN pressings of differing average crystal sizes and/or specific surface areas.

Investigating the electronic, optical, elastic, and mechanical properties of cubic CsPbI3 under varying stress conditions: A computational analysis using density functional theory

This research investigates the electronic, optical, elastic, and mechanical characteristics of cubic Cesium Lead Iodide CsPbI3 perovskite by utilizing the Generalized Gradient Approximation method under varying stress conditions ranging from 0 to 13[Formula: see text]GPa. Using the Density Functional Theory, the research demonstrates that electronic parameters, such as the electronic band gap, the partial density of states, and the total density of states, are impacted by applied stress. The band gap becomes zero at 14[Formula: see text]GPa. Significant changes are also noted in optical parameters, such as absorption, conductivity, reflectivity, dielectric function, loss function, and refractive index. The study also identifies changes in elastic properties, including elastic constants as well as an exponential rise in mechanical properties, such as Young’s modulus, bulk modulus, and shear modulus. Furthermore, the study finds that Poisson’s ratio, Cauchy pressure, Pugh’s ratio, and Frantsevich’s ratio experience irregular changes. These discoveries provide valuable insights into the properties of CsPbI3, which could aid in the development of semiconducting devices, transparent coatings, and lenses.

Computational homogenization of linear elastic properties in porous non-woven fibrous materials

Porous non-woven fibrous media are widely used in various industrial applications such as filtration, insulation, and medical textiles due to their unique structural and functional properties. However, predicting the mechanical behavior of these materials is challenging due to their complex microstructure and anisotropic nature. In this study, a computational model is developed to simulate the mechanical response of porous non-woven fibrous media under external loading. The model is based on the finite element method and takes into account the geometric and material properties of the fibers and the void spaces between them. The effects of various factors such as fiber size, porosity, and fibers’ intersection ratio on the mechanical behavior of the material are investigated. The results reveal that the material’s porosity and fibers’ intersection ratio are the most significant factors influencing its mechanical properties. Additionally, the increase in fiber diameter has a relatively minor effect on the material’s elastic properties. However, such changes in elastic properties are primarily attributed to the increase in randomness within the fibrous network, which is directly related to the fiber diameter for the investigated structure. The proposed computational model predicts the mechanical properties of porous non-woven fibrous media and can provide invaluable insights into the design and optimization of porous non-woven fibrous media for various scientific and engineering applications.

Characterizing and Quantifying Material Fatigue of the Artificial Urinary Sphincter Pressure Regulating Balloon

ObjectiveTo characterize and quantify changes in elastic properties and in vivo pressure characteristics of pressure regulating balloons (PRB) over time, we conducted an analysis of the mechanical characteristics of the PRB after removal from patients for revision surgery. MethodsPressure and elasticity characteristics of new and used 61-70cmH20 PRBs were analyzed. Pressure-volume curves were generated using commercially available urodynamics equipment. PRB pressures were measured at a standard fill volume (23cc). Elastance was calculated by the slope of the tangent line at the inflection point of the pressure-volume curve. Tests were repeated 5 times per PRB and intraclass correlations were used to gauge test-retest reliability. Regression models were used for continuous variables based on data distribution. ResultsTwenty-seven used PRBs were analyzed after excluding three for alternative pressure ratings and two for occult pinpoint leaks. Time from AUS placement to removal ranged from 0.02 to 17.6 years (median 8.4, IQR 5.7-10.0). The mean pressure of all extracted PRBs: 58.8cmH2O (±7.4), 17 (62.9%) below the standard operating range. Each year of use in-vivo was associated with 1.09cmH20 pressure loss on linear regression (p<0.01 CI -1.52 to -0.65). PRB pressures were not significantly different according to indication for removal (one-way ANOVA p=0.11). Loss of elastance was non-linear, decreasing by 1.9% per year on Poisson regression (p<0.01, CI -0.03 to -0.01). When accounting for PRB age, PRB pressure was independently associated with detrusor overactivity. ConclusionsIn PRBs tested for pressure-volume characteristics, increasing PRB age was associated with decreased pressure and elasticity.

Risk assessment of reactive local sand use in aggregate mixtures for structural concrete

Potential use of marginal fine aggregate in concrete is hindered by prescriptive quality requirements for concrete constituents. Experimental tests were performed on eleven mixtures of coarse and fine aggregates of variable susceptibility to alkali silica reaction (ASR). The miniature concrete prism test was applied for evaluation of ASR-induced expansion and associated changes of elastic properties were evaluated using the resonance modulus testing. Substitution of nonreactive sand with sands of moderate reactivity resulted in a relative increase in concrete expansion by 19–112% and substantial reduction of its elastic properties during the exposure to accelerated ASR environment. The Kolmogorov-Avrami-Mehl-Johnson model, modified to incorporate separately the effects of moderate reactivity of coarse and fine aggregate fractions, successfully described the kinetics of ASR-induced expansion. Beneficial effects of blastfurnace slag used for partial replacement of Portland clinker in blended cements were captured for aggregate combinations.