Search

In this paper, the effects of hydrostatic stress on the magnetic properties of Mn-Zn power ferrites are discussed. Ring cores were embedded in cement and the curing process gradually exerted pressure on the core. A novel testing method was developed to continuously measure the power losses and the magnetic susceptibility in dependence on magnetic excitation at a fixed frequency and room temperature with a vector network analyzer. After 450 h, a maximum compressive stress of 120 MPa was reached. Power loss up to 300% was observed, while magnetic susceptibility dropped by 35%. The magneto-mechanical effect on core losses was simulated with the Hodgdon–Esguerra hysteresis model, showing excellent agreement with tested results, which allows us to predict the behavior of ferrite tiles embedded in load-bearing surfaces for wireless power transfer (WPT) applications. [ABSTRACT FROM AUTHOR]

A comparative study of the structural integrity of an opaque recycled poly(ethylene terephthalate) (rPET-O) has been carried out with two types of modified rPET-O by applying reactive extrusion techniques, namely (a) using a multi-epoxide reactive agent (REx-rPET-O) and (b) a 90/10 (wt/wt) rPET-O/polycarbonate (PC) blend. The chemical modifications introduced during reactive extrusion were confirmed using differential scanning calorimetry (DSC) and rheological dynamic analysis (RDA). For the quantification of the fracture parameters, an instrumented pendulum impact testing machine was used using specimens in SENB configuration. The structural modifications generated during reactive extrusion promote an increase of between 16 (REx-rPET-O) and 20% (rPET-O/PC) in the stress-intensity factor (KQ) compared to unmodified rPET-O. The most significant differences between both modifications are registered in the "specific work of fracture" (wf) (alternative parameter to the standardized impact strength), where an increase of 61% is reached for the case of rPET-O/PC and only 11% for REx-rPET-O. This trend can be attributed to the type of reactive modification that is generated, namely chain branching (REx-rPET-O) vs. the generation of a random copolymer "in situ" (rPET-O/PC). This copolymer decreases the crystallization capacity and degree of crystalline perfection of rPET-O, promoting an increase in the critical hydrostatic stress conditions for the generation of crazing and crack propagation. [ABSTRACT FROM AUTHOR]

This article investigates the influence of an electromagnetic field on the surface of an elastic semiconductor material in a scenario where deformation occurs in just one dimension. The problem is solved by employing the two-temperature theory to examine the interactions between plasma and thermoelastic waves in a generalized thermoelastic half-space. The study examines the impacts of changing thermal and electrical conductivity. We examine the influence of the initial hydrostatic stress and a small mechanical strain on a photothermal transfer mechanism. The Laplace transform (LT) technique is employed to compute the constitutive relationships, governing equations, and various parameters of the thermo-electro-magnetic medium. To determine the principal physical parameters in the Laplace domain, the interface close to the vacuum is subjected to mechanical forces, temperature constraints, and plasma boundary conditions. The numerical method is employed to inverse the LT and offer comprehensive solutions in the time domain for the primarily investigated physical phenomena. We have performed a visual examination of how the thermoelectric and thermoelastic properties, as well as two-temperature variables of the applied force, affect the distributions of carrier density, force stress, temperature, and displacement components. [ABSTRACT FROM AUTHOR]

Most metal turning processes utilize cutting fluids. Despite extensive experimental and analytical studies, the mechanisms of chip formation under consideration of a cutting fluid are still not entirely understood. Due to fluid-structure interaction, simulating wet cutting processes for an extended duration has not been feasible. The primary objective of this study is to utilize a simulation approach to provide additional information about the wet chip formation process in contrast to measurement methods, with a view to drawing conclusions. As methodology the Finite-Pointset-Method (FPM) is employed to simulate the chip formation process for dry, flood and specifically high-pressure cooling conditions during machining of carbon steel C45 as well as nickel-based alloy Inconel 718. Due to the increased relative velocity between workpiece and cutting fluid with the use of high-pressure cooling compared to flood cooling, numerical stability issues are present. Initially, the modeling approach to handle high-pressure cooling conditions is described and validated by an impact test. Subsequently the cutting simulation model is presented in detail and verified by measurements. The simulation results of stress, temperature and plastic strain rate fields are used to elucidate the observed discrepancies between various cutting fluid strategies in detail. These findings suggest explanations for the high efficiency of high-pressure cooling such as a decline of hydrostatic stresses or activation of ductile damaging. [ABSTRACT FROM AUTHOR]

Environmentally assisted cracking can significantly affect the performance of high strength alloys and limit material selection to minimize the risk of subcritical crack growth in service. UNS N07718 is widely used in marine service applications and under a variety of conditions, such as: alternate immersion, different levels of cathodic protection, and freely corroding galvanic couples, because of its demonstrated corrosion and fracture resistance in these environments. In this work we developed a representative model of the material microstructure including the metal grains, the material texture, and the precipitates along the grain boundaries and within the grains. The microstructural model was subjected to the boundary conditions identified at the notch root of a fracture mechanics sample and the results are used as input for a simulation of hydrogen diffusion from the surface of the notch, assuming the material has been introduced to a hydrogen producing environment. The diffusion of hydrogen was modeled by Fick's law and included both hydrostatic stress and mobile dislocation velocity as driving forces. The influence of immobile dislocations was also modeled to account for the irreversible trapping. The results show that hydrostatic stress and immobile dislocation trapping can significantly alter the highest concentration of hydrogen and its location within the microstructure towards the fracture process zone. Mobile dislocation velocity has a small influence in determining the hydrogen distribution near the fracture process zone. [ABSTRACT FROM AUTHOR]

We report the crack growth on peak aged Al 7075 under tensile loading in a saltwater environment to investigate whether hydrogen plays a role in the initiation and the subsequent growth of the crack. As the hydrostatic stress is at a maximum ahead of the notch, it has been speculated that hydrogen would diffuse to region of maximum hydrostatic stress and initiate the crack. An elastic-plastic finite element (FE) model is developed to determine the stress distribution around the circular notch at the edge of the plate. The crack growth was monitored using a camera attached with an optical microscope, and various regimes corresponding to hydrogen evolution, pit formation and growth, crack nucleation and initial growth and rapid crack growth leading to failure have been identified. We observe the crack was nucleated in a region associated with the highest hoop stress instead of the maximum hydrostatic stress from the base of a pit at the circular notch. We demonstrated the crack growth rate in a salt water environment is governed mostly by the dissolution of grain boundary MgZn2 precipitate, rather than the hydrogen induced decohesion mechanism. [ABSTRACT FROM AUTHOR]

A complete closed-form solution is derived to the finite plane elasticity problem associated with an elliptical incompressible liquid inclusion embedded in an infinite compressible hyperelastic matrix of harmonic type subjected to uniform remote in-plane Piola stresses. The internal uniform hydrostatic Piola stresses and deformation gradients within the elliptical incompressible liquid inclusion are obtained. The internal uniform hydrostatic tension and hoop stress on the matrix side along the liquid-solid interface for various shapes of the elliptical liquid inclusion and different elastic constants of the matrix under various remote loadings are calculated. [ABSTRACT FROM AUTHOR]

Since many years ago, ultrasonic velocity has been used to investigate the physical and mechanical behaviour of rocks, thereby playing an important role in reservoir characterization and seismic interpretation. In order to develop the knowledge of ultrasonic tools, I performed a noble analysis on the ultrasonic behaviour of rocks under confining stress and evaluated a distinctive property of porous media that is measured as the area under the stress–velocity curve (here defined as S*). I further investigated its relationship with elastic and mechanical behaviours of rock. To validate the theoretical framework developed in this work, 20 core plugs from various rock units with complex microstructures were subjected to triaxial compressional tests to calculate their area under the curve. Calculations were made for crack‐closing, elastic and post‐elastic stages (e.g. pore collapse) along the ultrasonic velocity–stress curve. Moreover, the selected samples had their microstructure investigated by thin‐section studies to quantify their porosity and pore type. The results were analysed to check for the effect of pore type on S* in different stages of the stress–velocity curve. Based on the outputs of the analysis of variance and Pearson's correlation coefficient analysis, the curve had its shape and underlying area closely related to the porosity and pore geometry. Indeed, the results showed that the shale and sandstone with micro cracks and carbonate with stiff pores correspond to smaller and larger areas under the curve in crack‐closing and inelastic stages, respectively. Cross‐correlating the results to compressibility (inverse of bulk modulus), it was figured out that the calculated area under curve was well consistent with the compressibility. In addition, S* represents both static and dynamic behaviours of the rock, and the results revealed that the shape and curvature of the stress–velocity curve give valuable information about the rock microstructure. Another finding was the fact that the type of fluid and wave velocity seemingly affect the S*. Our findings can help interpret wave velocity behaviour in reservoir rocks and other stressful porous media. [ABSTRACT FROM AUTHOR]

The role of stress-induced diffusion (SID) in influencing the mechanical response and diffusion of Li in viscoelastic electrode particles of Lithium-ion batteries is studied. A two-way coupled chemo-viscoelastic model is developed for this purpose, and the governing equations are solved via the finite element method using deal. ii, an open source C++ library. Comparative studies between one-way and two-way coupled chemo-viscoelastic models reveal that concentration and stress are initially larger for the two-way coupled model, but later they reduce in magnitude compared to the one-way coupled model. The level of filling at which the switch is observed decreases with increase in particle size. The switch occurs due to change in the sign of gradient of hydrostatic stress for a viscoelastic material from negative to positive and its concurrent effect on diffusive flux as a result of two-way coupling between stress and diffusion. Further, from comparative studies between two-way coupled elastic and viscoelastic models, it is observed that speed of filling is greater for an elastic particle in comparison to a viscoelastic particle, and the gap increases when the particle size is smaller. In addition, lower values of stresses are observed for viscoelastic electrode particles, and the difference between maximum stress generated increases with increase in particle size. Thus, the time scales associated with viscoelastic constitutive response and diffusion process alters the SID effects and could be tuned while designing electrodes to mitigate slowing down of diffusion and fracture. [ABSTRACT FROM AUTHOR]

The yield stress of rubber-modified epoxy adhesives is affected by hydrostatic stress in the adhesive layer. It is necessary to clarify whether hydrostatic stress modeling is essential for highly toughened epoxy adhesives and how hydrostatic stress should be considered under high multiaxial stress conditions. The elastic–plastic stress–strain behavior of a film-type epoxy adhesive AF163-2U was examined using a bulk adhesive tension test and a thick adherend shear test (TAST). The exponent Drucker–Prager model with an appropriate hydrostatic-stress sensitivity parameter (λ-parameter = 1.639) fully described the stress–strain curves both for the bulk adhesive tension test and TAST. The Hill'48 model of hydrostatic-stress-independent plasticity also simulated the bulk adhesive tension test and TAST as a response by determining the appropriate anisotropic parameters. To examine the effect of extremely high hydrostatic stress, a butt-joint tensile test and a finite element (FE) simulation were conducted using the exponent Drucker–Prager and Hill'48 models. The Hill'48 model completely failed in the butt-joint tensile test simulation. The exponent Drucker–Prager model, where a higher λ-parameter (=2.1) was required; consequently, it was concluded that the hydrostatic-stress effect should be considered for the adhesive model and the λ-parameter is not a fixed value but increases with increasing hydrostatic stress. [ABSTRACT FROM AUTHOR]

AbstractThe primary objective of the current work is to establish the impacts of planar boundary and non-planar boundary on the displacement components (DCs) of Rayleigh-type wave propagation in an elastic structure. The elastic structure, precisely, incorporates a pre-stressed nearly incompressible elastic material in the half-space along with the non-planar boundary at the free surface. The methodology applied features variable separable technique and Taylor’s series expansion along with substitution method to establish the expressions for DCs and frequency relation. The frequency relation of Rayleigh-type wave is obtained for the situation considering planar free surface, which is further reduced as a special case of the study and validated with the classical result present in the literature. The DCs of Rayleigh-type wave have been numerically computed, and their reliance on wave number have been exhibited graphically. In addition to this, the influences of affecting parameters viz., hydrostatic stress, principal Cauchy stress and curvature parameter on DCs have been traced out. The computational result also manifests the domain of existence of Rayleigh-type wave propagating in the considered model in the presence of planar free surface. [ABSTRACT FROM AUTHOR]

The values of primary stresses are not allowed for as a criterion in the selection of roof bolting systems in mining excavations located at various depths in Polish copper ore mines. Therefore, in order to ensure enduring and safe operation of excavations, in particular, those driven in unfavourable geological and mining conditions, this problem has required solutions based on numerical methods. This article presents an example of applying numerical simulations to the evaluation of the stability of headings in Polish copper ore mines. The analyses included mining excavations located at various depths in the rock mass. This issue is of great importance, as safety regulations are prioritised in mining excavations which remain in operation even for several decades. The stability of the headings was evaluated with the use of the RS2 specialist numerical simulation software. This computer program uses the finite element method (FEM) for calculations. The rock parameters used in the numerical models have been determined on the basis of the Hoek–Brown classification. For that purpose, the RocLab 1.0 software was used. The parameters of the stress field were identified from the profile of the GG-1 shaft with the assumed hydrostatic state of stress. The numerical modelling was performed in a triaxial stress state and in a plane strain state. The numerical analyses were based on the Mohr–Coulomb failure criterion. The rock medium was described with the elastic-plastic model with softening (roof and walls) and with the elastic-plastic model (floor). The results of the numerical analyses served to provide an example of the application of a roof bolting system to protect headings located at the depths of 1000 m b.g.l. and 1300 m b.g.l. [ABSTRACT FROM AUTHOR]

Hydrogen embrittlement in ductile metals, such as steel, is a significant concern, for instance, in the safety assessment of existing pipeline infrastructure intended for hydrogen transport. The ductile damage mechanism in steels is characterized by the nucleation, growth, and coalescence of microvoids, which is further enhanced by the presence of hydrogen. This leads to material damage and premature failure in components. Mechanisms contributing to hydrogen‐induced reduction of strength in steels include hydrogen‐enhanced decohesion (HEDE), hydrogen‐enhanced local plasticity (HELP), and hydrogen‐enhanced strain‐induced vacancies (HESIV). The HEDE mechanism leads to a principal stress‐controlled brittle failure mode. Conversely, the HELP and the HESIV mechanisms, which are dominated by plastic deformation, alter the ductile damage behavior as they lead to accelerated void growth and coalescence. Furthermore, interstitial diffusion of hydrogen leading to lattice expansion, commonly referred to as swelling, also contributes to hydrogen‐induced embrittlement. Hydrogen embrittlement is therefore a stress‐diffusion process that involves chemo‐mechanical coupling, where hydrogen atoms primarily diffuse toward areas with high hydrostatic stress. In this regard, we propose a framework using the finite element method and combining coupled chemo‐mechanics and the well‐known Gurson‐Tvergaard‐Needleman (GTN) damage model. The framework is motivated by mixed rate‐type potentials, that account for the influence of hydrogen concentration on the damage behavior. An additional dependence of the fracture strain and evolution of the void volume fraction on hydrogen is included. A comparison of the fully‐coupled model to simplified versions is conducted to individually assess the role of hydrogen concentration on damage evolution and the stress state on diffusion. [ABSTRACT FROM AUTHOR]

In open flow simulations, the dispersion characteristics of disturbances near synthetic boundaries can lead to unphysical boundary scattering interactions that contaminate the resolved flow upstream by propagating numerical artifacts back into the domain interior. This issue is exacerbated in flows influenced by real or apparent body forces, which can significantly disrupt the normal stress balance along outflow boundaries and generate spurious pressure disturbances. To address this problem, this paper develops a zero-parameter, physics-based outflow boundary condition (BC) designed to minimize pressure scattering from body forces and pseudo-forces and enhance transparency of the artificial boundary. This "balanced outflow BC" is then compared against other common BCs from the literature using example axisymmetric and three-dimensional open swirling flow computations. Due to centrifugal and Coriolis forces, swirling flows are known to be particularly challenging to simulate in open geometries, as these apparent forces induce non-trivial hydrostatic stress distributions along artificial boundaries that cause scattering issues. In this context, the balanced outflow BC is shown to correspond to a geostrophic hydrostatic stress correction that balances the induced pressure gradients. Unlike the alternatives, the balanced outflow BC yields accurate results in truncated domains for both linear and nonlinear computations without requiring assumptions about wave characteristics along the boundary. [ABSTRACT FROM AUTHOR]

Blasting excavation of rock masses under high in-situ stress often encounters difficulties in rock fragmentation and a high boulder rate. To gain a deeper understanding of this issue, the stress distribution of rock masses under dynamic and static loads was first studied through theoretical analysis. Then, the ANSYS/LS-DYNA software was employed to simulate the blasting crack propagation in rock masses under various in-situ stress conditions. The fractal dimension was introduced to quantitatively analyze the influence of in-situ stress on the distribution of blasting cracks. The results indicate that in-situ stress primarily affects crack propagation in the later stages of the explosion, while crack initiation and propagation in the early stages are mainly driven by the explosion load. In-situ stress significantly influences the damage area and fractal dimension of cut blasting. Under hydrostatic in-situ stress, as the in-situ stress increases, the damage area and fractal dimension of blasting cracks gradually decrease. Under non-hydrostatic in-situ stress, when the principal stress difference is small, in-situ stress promotes the damage area and fractal dimension of the surrounding rock, enhancing rock fragmentation. However, when the principal stress difference is large, in-situ stress inhibits the damage area and fractal dimension of the surrounding rock, hindering effective rock breaking. [ABSTRACT FROM AUTHOR]

Hydrostatic pressure is a common mechanical stressor that modulates metabolism and reduces cell viability. Eukaryotic cells have genetic programs to cope with hydrostatic pressure stress and maintain intracellular homeostasis. However, the mechanism underlying hydrostatic pressure tolerance remains largely unknown. We have recently demonstrated that maintenance of telomere capping protein 6 (Mtc6) plays a protective role in the survival of the budding yeast Saccharomyces cerevisiae under hydrostatic pressure stress by supporting the integrity of nutrient permeases. The current study demonstrates that Mtc6 acts as an endoplasmic reticulum (ER) membrane protein. Mtc6 comprises two transmembrane domains, a C-terminal cytoplasmic domain and a luminal region with 12 Asn (N)-linked glycans attached to it. Serial mutational analyses showed that the cytoplasmic C-terminal amino acid residues GVPS Mtc6 activity. Multiple N-linked glycans in the luminal region are involved in the structural conformation of Mtc6. Moreover, deletion of MTC6 led to increased degradation of the leucine permease Bap2 under hydrostatic pressure, suggesting that Mtc6 facilitates the proper folding of nutrient permeases in the ER under stress conditions. We propose a novel model of molecular function in which the glycosylated luminal domain and cytoplasmic GVPS sequences of Mtc6 cooperatively support the nutrient permease activity. [ABSTRACT FROM AUTHOR]

Similar to conventional blanking, there are some characteristics, such as rollover, burnish, and fracture on the sides of micro blanked parts, and rollover height and fracture height vary with the blanking clearance. This paper attempts to reveal the effect of blanking clearance on the rollover height. An uncoupled ductile fracture criterion is used to describe the effect of the blanking clearance on the fracture height. The experimental and simulation results show that the increase in hydrostatic stress gradient on the foil around the die edge results in an increase in rollover height. The coefficients of the uncoupled ductile fracture criterion are determined by the method of inverse solution and data fitting. The criterion is evaluated by mean-square error to ensure its validity. This analysis method has been verified by micro brass blanked part. [ABSTRACT FROM AUTHOR]

Electromigration (EM) is a critical reliability issue in integrated circuits and is becoming increasingly significant as fabrication technology nodes continue to advance. The analysis of the hydrostatic stress, which is paramount in electromigration studies, typically involves solving complex physical equations (partial differential equations, or PDEs in this case), which is time consuming, inefficient and not practical for full-chip EM analysis. In this paper, a novel approach is proposed, conceptualizing circuit interconnect trees as a graph within a graph neural network framework. Using finite element solution software, ground truth hydrostatic stress values were obtained to construct a dataset of interconnected trees with hydrostatic stress values for each node. An improved Graph Convolutional Network (GCN) augmented with edge feature aggregation and attention mechanism was then trained employing the dataset, yielding a model capable of predicting hydrostatic stress values for nodes in an interconnect tree. The results show that our model demonstrated a 15% improvement in the Root Mean Square Error (RMSE) compared to the original GCN model and improved the solution speed greatly compared to traditional finite element software. [ABSTRACT FROM AUTHOR]

The current investigation deals with the deformation of a non-homogeneous thermoelastic half space under hydrostatic initial stress for the Green–Naghdi model III. The medium is supposed to be rotating with a constant angular velocity. The non-homogeneous properties of the material are along the x-direction. At the first instance, the problem has been solved analytically to obtain stress and displacement components. Further, the numerical values of these expressions are evaluated using a computer program for a particular medium. The numerical values obtained are then presented graphically to show the effect of initial stress parameter and non-homogeneity parameter on the quantities. [ABSTRACT FROM AUTHOR]

Background: Polymeric foam materials can show a strongly non linear compressible elastic response. For certain applications, it is necessary to know the volumetric behavior of the material under hydrostatic compression. Existing devices for hydrostatic compression testing use a multiaxial testing machine or a fluid to transmit pressure to the foam. They are either complex to set up, or do not allow for hydrostatic pressures of several MPa to be applied or for volume variations of several tens of percent to be achieved. Besides, when pressure is applied to the sample via a fluid, it is difficult to prevent penetration of the fluid into the foam, particularly when it is open-cell. Objective: This paper presents a hydrostatic compression test for polymeric foams that does not present these limitations. Methods: A cylinder of a nearly incompressible material (silicone) is molded around a spherical sample of the polymeric foam of interest. The whole set is subjected to confined compression in a rigid chamber. Post-processing is developed, based on finite element analysis, to determine the hydrostatic stress in the foam and its volume ratio from the axial load and displacement data. Results: Finite element simulations show that the foam sample is subjected to a state close to hydrostatic compression. The test was applied to several samples of elastomeric microcellular polyurethane foams of different densities. The results are in line with expectations, with limited scattering. Conclusions: The Sphere Foam In Rubber (SFIR) test allows to reach volume reductions of several tens of percents and hydrostatic stress levels of several MPa, on any kind of polymeric foams, provided that its bulk modulus is at least 100 times lower than that of the surrounding nearly incompressible material used. It can be easily implemented with very standard equipment. [ABSTRACT FROM AUTHOR]

Functional triblock copolymers (BCPs), i.e., poly(glycidyl methacrylate/methyl methacrylate)-b-poly(lauryl methacrylate)-b-poly(glycidyl methacrylate/methyl methacrylate) triblock copolymers [(P(GMA/MMA)-b-PLMA-b-P(GMA/MMA)], were investigated as toughening modifiers for all-methacrylate polymer blends. Methyl methacrylate (MMA) was copolymerized with methacrylic acid (MAA) in the presence of the BCPs. Without MAA in the polymethacrylate matrices, the BCP blends formed micron-scale phase structures by polymerization-induced phase separation. In matrices copolymerized with MAA, self-assembled nanostructures, such as curved lamellae, worm-like cylindrical micelles, or spherical micelles were formed. The BCP blends with worm-like cylindrical nano-micelles achieved much higher fracture toughness than those with spherical nano-micelles. The toughening mechanisms were elucidated by transmission electron microscopy. Cavitation was initiated in worm-like cylindrical nano-micelles, and the aligned cavitation formed craze-like deformation with increased loads. This relieves hydrostatic tensile stress in front of the crack tip, forming a large shear yield zone within the craze-like deformation region, contributing to high toughness. [ABSTRACT FROM AUTHOR]

Due to their excellent mechanical properties, the carbon fiber-reinforced polymer composites (CFRPs) of thermoplastic resins are widely used, and an accurate constitutive model plays a pivotal role in structural design and service safety. A two-parameter three-dimensional (3D) plastic potential was obtained by considering both the deviatoric deformation and the dilatation deformation associated with hydrostatic stress. The Langmuir function was first adopted to model the plastic hardening behavior of composites. The two-parameter 3D plastic potential, connected to the Langmuir function of plastic hardening, was thus proposed to model the constitutive behavior of the CFRPs of thermoplastic resins. Also, T700/PEEK specimens with different off-axis angles were subjected to tensile loading to obtain the corresponding fracture surface angles of specimens and the load–displacement curves. The two unknown plastic parameters in the proposed 3D plastic potential were obtained by using the quasi-Newton algorithm programmed in MATLAB, and the unknown hardening parameters in the Langmuir function were determined by fitting the effective stress-plastic strain curve in different off-axis angles. Meanwhile, the user material subroutine VUMAT, following the proposed constitutive model, was developed in terms of the maximum stress criterion for fiber failure and the LaRC05 criterion for matrix failure to simulate the 3D elastoplastic damage behavior of T700/PEEK. Finally, comparisons between the experimental tests and the numerical analysis were made, and a fairly good agreement was found, which validated the correctness of the proposed constitutive model in this work. [ABSTRACT FROM AUTHOR]

Polyamides can absorb or desorb water from or to their surrounding environment. The impact of this process is significant as water molecules lead locally to a swelling and a coupling of diffusion and deformation behavior. To model these phenomena, a strongly coupled chemo-mechanical (or diffuso-mechanical) model is required, considering both local water concentration and the viscoelastic material behavior of polyamide. In the present work, we derive and apply such a model to polyamide 6. A diffusion equation describing changes in water concentration is coupled to the balance of linear momentum in polyamide 6. The interaction between deformation and concentration is derived from thermodynamic considerations by introducing a free energy consisting of a mechanical and a chemical part. The mechanical part describes a linear viscoelastic model and includes chemical strains due to the presence of water molecules. The chemical part builds upon the theory of Flory and Huggins, that takes into account changes in enthalpy and entropy of mixing due to the interaction of polymer and water molecules. The coupling of deformation to water concentration arises due to a dependency of the water flux on the hydrostatic stress inside the polyamide. We successfully apply the derived model in Finite-Element simulations to predict the drying of polyamide 6 specimens without any coupling to mechanical loads. In addition, we reproduce experimentally obtained data from relaxation measurements, where the drying of polyamide specimens leads to an increase in relaxation modulus. [ABSTRACT FROM AUTHOR]

Clay formations present very favourable conditions for the long-term containment of radioactive waste due to their low hydraulic conductivity, high radionuclide retention capacity and limited fracturing in their natural state. But it is also due to the very low permeabilities of clays and claystone that drained conditions occur only at very slow temperature increases. The response is then partially drained or undrained with the consequence of thermal pressurisation induced by the thermal gradient. Furthermore, thermo-hydro-mechanical characterisations under drained and undrained conditions carried out on samples of the Callovo-Oxfordian (COx) clay formation and in situ experiments performed by Andra at the Meuse/Haute-Marne underground research laboratory (LS M/HM) have also highlighted the strongly coupled and complex thermo-hydro-mechanical processes of this material. In particular, the volume changes of the COx claystone, subjected to a temperature rise under a constant isotropic stress close to the in situ conditions of the LS M/HM laboratory in saturated and drained conditions, were highlighted. A behaviour comparable to that of over-consolidated clays depending on temperature is then experimentally observed, i.e. thermoelastic expansion followed by thermoplastic contraction: the transition temperature between these two volumetric deformation mechanisms would correspond to the maximum temperature value undergone by the COx claystone during its geological history. Based on the extensive literature on the thermomechanical behaviour of clays and clayey soils, recent thermo-hydro-mechanical tests conducted on COx samples, as well as the database on the instantaneous behaviour of COx claystone, a constitutive model for the thermomechanical behaviour of COx claystone is proposed, then implemented in a commercial computation code. The transverse isotropic elastic and then elastoplastic instantaneous behaviour (beyond the elastic limit) up to the peak strength of the COx claystone, thermoplastic and hydrostatic compactions are taken into account. The model is first validated on triaxial and hydrostatic paths. The simulation of one of the drained hydrostatic stress heating tests performed by Braun et al. verified that the proposed model was able to reproduce the thermal compaction phenomenon highlighted by the authors and to show its operational character. Highlights: As for over-consolidated clays, the volume changes of COx claystone subjected to temperature rise exhibit a thermoelastic expansion followed by thermoplastic compaction. The transition temperature between these two volumetric mechanisms would correspond to the maximum temperature undergone by the COx during its geological history. A thermo-elasto-plastic model is proposed by incorporating the observed non-linear behaviour of the COx claystone up to its strength, with the two volumetric strain mechanisms. The proposed model is implemented in the commercial geomechanical software, FLAC3D. After checking the model on triaxial stress paths, the drained hydrostatic stress heating tests performed by Braun et al. are used to validate the proposed model. [ABSTRACT FROM AUTHOR]

To study the failure (strength) regularities of rocks under complex stress states, we propose a novel three-parameter deviatoric function that includes the shape of the failure envelope on the Mohr–Coulomb (MC), Ottosen, Bigoni–Piccolroaz, and Wu–Zhang deviatoric planes. This function realizes the deviatoric plane shape of numerous classic criteria, including the Rankine, Tresca, von Mises, generalized Tresca, MC, Drucker–Prager (DP), Matsuoka–Nakai (MN), Lade–Duncan (LD), and Ottosen. On this basis, taking the nonlinear characteristics of the power function, we establish a novel 3D NUF criterion, namely MCNUF and LDNUF criteria, where the novel parameter γ is based on the basic parameters of two classical criteria, MC and LD, respectively. Based on the triaxial test data of different rocks, the proposed MCNUF and LDNUF criteria are compared with the previous criteria (the generalized nonlinear failure criterion (MNGNF), the DP and MN unified (DPMNu) criterion). Results show that: (1) the internal friction angles predicted by each criterion are equal under the same meridian plane parameters. (2) For four kinds of rock materials, the prediction performance of the proposed criteria is generally better than that of the MNGNF and DPMNu criteria. (3) The proposed criteria describe the hydrostatic stress and IPS and their coupled effect on various rock materials. (4) The 3D graphical visualization of the proposed criteria is carried out systematically, which plays a positive guiding role in enriching and perfecting the strength theory. [ABSTRACT FROM AUTHOR]

Repurposing existing natural gas pipelines for hydrogen transport requires an accurate assessment of the distribution of hydrogen (H) atoms at defects, such as dents, under frequent pressure fluctuations experienced by gas pipelines. In this work, a 3-dimensional finite element-based model was developed to determine the stress/strain and H atom concentrations at an unconstrained dent on an X52 steel pipe which experienced denting, spring-back and cyclic loading processes. As expected, stress and strain concentrations generate at the dent center. However, the cyclic loading reduces the stress level and shifts the stress concentration zone from the dent center along the circumferential direction. As the dent depth increases, the maximum H atom concentration is further shifted from the dent center to the side. There are no certain relationships among the maximum H atom concentration, von Mises stress, hydrostatic stress, and plastic strain in terms of their distributions and quantities. Pressure fluctuations decrease both the stress and H atom concentrations at the dent, providing a beneficial effect on reduced risk of the dented pipelines to hydrogen embrittlement in high-pressure hydrogen gas environments. The indenter size has little influence on the H atom distribution in the dent area. [ABSTRACT FROM AUTHOR]

Certain metals experience a substantial deterioration in mechanical properties when exposed to a hydrogen environment, an effect termed hydrogen embrittlement. To understand, predict, and counteract this hydrogen‐assisted material degradation, sufficiently accurate material models are needed. According to the current hypothesis, hydrogen diffusion is driven by gradients of concentration and hydrostatic stress. To capture this, a phase‐field model is formulated as a multi‐field problem coupling deformation, crack propagation, and diffusion to analyze hydrogen‐promoted fracture. Here, the displacements, a fracture‐related phase‐field, the hydrogen lattice occupancy, and the chemical potential are considered as primary field variables. Approaches proposed in the literature often use an extrapolation of the hydrostatic stress calculated at the material point level onto the nodes and later use the B‐matrix to compute the gradient of hydrostatic stress. In order to circumvent this potentially inaccurate extrapolation, the model is recast into a mixed rate‐type variational setting, where the chemical potential—whose gradient governs the hydrogen flux—is obtained from the numerical solution of a saddle point problem. A representative boundary value problem is presented to demonstrate the applicability of the developed numerical framework. [ABSTRACT FROM AUTHOR]

This study aims to describe a toughened adhesive's ratcheting–recovery behavior under reversed cyclic load using a viscoelastic–viscoplastic model. As most adhesives are based on synthetic polymers, their tensile and compression response can be different. A series of load–Sunload tests were conducted on bulk adhesives and bonded joints involving tension/compression–shear loads to characterize the initial yield surface. The effect of hydrostatic stress was studied by considering the instantaneous response and yield strength under tensile and compression loads. Given the observed modulus degradation and extensive permanent strain during reversed cyclic tests, time-dependent damage factors were considered for both viscoelastic and viscoplastic responses. The model was implemented in a finite element (FE) code and used to model the shear response to reversed cyclic load with varying frequency. Good agreement between the model and experiment was obtained. The consideration of both hydrostatic stress and damage was required to describe the observed adhesive reversed cyclic response. [ABSTRACT FROM AUTHOR]

The features of diffusion in two-phase (duplex) stainless steel (DSS), interaction the effect of hydrogen with trap sites in various steel structures, the influence of plastic deformation, local stresses and hydrogen concentrations on localized corrosion and hydrogen embrittlement Available data indicate that the diffusivity of DSS is insensitive to plastic deformation and increase in dislocation density, but it is influenced by grain boundaries and interfaces α/γ-phases The influence of hydrogen on stability is considered γ-phases, formation of second phases and hydrogen trap semi-coherent grain boundaries. The mechanisms that ensure crack propagation are discussed: brittle, associated with decohesion in the region of maximum hydrostatic stress, and plastic in the austenite phase—due to shear decohesion along the slip plane. Reviewed the influence of the yield stress of duplex steel on the susceptibility to hydrogen embrittlement, as well as on correlation of the steel embrittlement index with the total amount of absorbed hydrogen. [ABSTRACT FROM AUTHOR]

The present paper is devoted to investigating the second-grade fluid system in a strip domain R times T. We obtain the global well-posedness result with small analytic initial datum and justify the limit strictly from the hydrostatic second-grade fluid system to the hydrostatic Navier--Stokes system. [ABSTRACT FROM AUTHOR]

This article discusses a method for estimating residual stresses in metal samples produced by additive manufacturing, specifically focusing on steel cylindrical bars produced by laser powder bed fusion (LPBF). The method involves making a partial longitudinal cut in the bar using electrical discharge machining (EDM) and measuring the resulting deflection to assess the contribution of residual stresses. The study combines experimental analysis with numerical simulation using finite element modeling (FEM). The proposed method allows for the estimation of residual stresses in the laboratory without the need for special equipment. The article also provides a list of references that cover various topics related to residual stresses and mechanical properties of additively manufactured stainless steel, which can be useful for further research. [Extracted from the article]

Hydride precipitation ahead of a crack is examined under conditions of hydrogen chemical equilibrium, constant temperature and elastic-plastic power-law hardening metal behavior. The limiting conditions are approached via the interaction of the operating physical mechanisms of material deformation, hydrogen diffusion and hydride precipitation. Hydrides are characterized by hydride volume fraction and isotropic transformation strain. Analytical relations are presented for hydride volume fraction and stress, as well as for hydride precipitation zone boundary. It is shown that there is an annulus, within the hydride precipitation zone, where stresses, although vary according to 1 / r 1 / n + 1 -singularity, deviate significantly from the well-known HRR-field, being smaller, according to the difference of hydrostatic stress before and after hydride precipitation. Hydride precipitation zone increases with crack-tip constraint, given by triaxiality parameter Q . [ABSTRACT FROM AUTHOR]

We apply Muskhelishvili's complex variable method to solve the plane strain problem associated with two circular incompressible liquid inclusions embedded in an infinite isotropic elastic matrix subjected to uniform remote in‐plane normal stresses. An analytical solution to the problem is derived primarily with the aid of conformal mapping and analytic continuation. To demonstrate our analytical solution, we present detailed numerical results characterizing the internal uniform hydrostatic stresses within the two liquid inclusions, the nonuniform hoop stresses along the two circular liquid‐solid interfaces on the matrix side and the nonuniform rigid body rotations within the two circular liquid inclusions. [ABSTRACT FROM AUTHOR]

Ice shelf calving constitutes roughly half of the total mass loss from the Antarctic ice sheet. Although much attention is paid to calving of giant tabular icebergs, these events are relatively rare. More frequent, smaller-scale calving events likely play an important role in the ice shelf frontal dynamics. Here, we investigate the role of bending stresses at the ice shelf front in driving calving on the scale 100 m – 1 km, perpendicular to the ice edge. We focus in particular on how buoyant underwater 'feet' that protrude beyond the above-water ice cliff may cause tensile stresses at the base of the ice and ultimately lead to fracture. Indirect and anecdotal observations of such feet at the Ross Ice Shelf front suggest that this process may be widespread. We consider satellite observations, together with an elastic beam model and a parameterization of frontal wave erosion to estimate the size and frequency of such calving events. Our results suggest that foot-induced mass loss at Ross Ice Shelf may cause up to 25 % of the total frontal ablation. However, stresses induced through this process are likely not sufficient to initiate crevassing but rather act to propagate existing crevasses. In addition, the relatively strong ice thickness dependence of the frontal uplift suggests an important role for internal bending moments due to temperature gradients in the ice. The highly variable environment, irregularity of pre-existing crevasse spacing, and complex rheology of the ice continue to pose challenges in better constraining the drivers behind the observed deformations and resulting calving rates. [ABSTRACT FROM AUTHOR]

In order to study the effects of notched parameters on the hydrogen embrittlement (HE) behaviors of pipeline steel in hydrogen-blended natural gas environments, the mechanical properties of notched X80 steel specimens with various depth (δ), angle (ω) and curvature radius (ρ) were studied using slow strain rate tensile (SSRT) tests combined with scanning electron microscope (SEM) and finite element analysis (FEA). The tests indicate that the presence of notches greatly reduces the fracture strain, and increases the sensitivity of the specimen to HE. The geometric shape of the notch greatly affects the HE sensitivity of the notch specimen. The sharper the geometric shape of the notch, the higher the hydrostatic stress at the notch root, and the higher the diffusion hydrogen concentration, thereby increasing the hydrogen embrittlement sensitivity of the specimen. In addition, specimen with shallow notches also exhibits high hydrogen embrittlement sensitivity due to its shorter hydrogen atom diffusion distance. • The sharper the notch geometry, the higher the hydrogen embrittlement sensitivity. • The shallower the notch, the easier hydrogen atoms accumulate at the notch root. • The hydrostatic stress distribution affects hydrogen concentration distribution. • The lower stress concentration, the lower hydrogen embrittlement sensitivity. [ABSTRACT FROM AUTHOR]

The work investigates failure criteria and mean stress correction approaches for the fatigue lifetime prediction of two hyperelastic adhesives (a polyurethane, PU, and a silicon-modified polymer, SMP). Fatigue experiments are carried under constant amplitude cyclic loading at RT and 40°C/60% r.h with butt- and the thick-adherend-shear-test-joints at three stress ratios R = −1, 0.1 and 0.5. Three mean stress correction approaches are evaluated: Goodman (static strength based), Schütz (mean stress sensitivity based) and Kujawski & Ellyin (parameter optimisation based). Fatigue failure criteria considered are: Drucker-Prager (linear-relation with the hydrostatic stress), Beltrami (quadratic relationship with the hydrostatic stress), and a multivariable nominal shear and tensile stresses criterion (data-based). The comparison is based on prediction accuracy (R-squared of master SN curves) and complexity of parameter determination. The highest values of R-squared were obtained by the Kujawski and Ellyin correction, followed by Schütz and then Goodman. However, the complexity of parameter determination follows an opposite trend with Goodman being the lightest approach. Failure criteria yielded comparable results with the multivariable criterion having the advantage of not dealing with FEA, but being limited to joints with nearly uniform stress distribution. Finally, compared to Drucker-Prager, the Beltrami criterion had a more robust parameter determination. [ABSTRACT FROM AUTHOR]

We use Muskhelishvili's complex variable formulation to study the interaction problem associated with a circular incompressible liquid inclusion embedded in an infinite isotropic elastic matrix subjected to the action of an edge dislocation at an arbitrary position. A closed-form solution to the problem is derived largely with the aid of analytic continuation. We obtain, in explicit form, expressions for the internal uniform hydrostatic stresses, nonuniform strains and nonuniform rigid body rotation within the liquid inclusion; the hoop stress along the liquid-solid interface on the matrix side and the image force acting on the edge dislocation. We observe that (1) the internal strains and rigid body rotation within the liquid inclusion are independent of the elastic property of the matrix; (2) the internal hydrostatic stress field within the liquid inclusion is unaffected by Poisson's ratio of the matrix and is proportional to the shear modulus of the matrix; and (3) an unstable equilibrium position always exists for a climbing dislocation. [ABSTRACT FROM AUTHOR]

Hydride precipitation ahead of a crack is examined under conditions of hydrogen chemical equilibrium, steady-state heat conduction and linear elastic metal behavior. The limiting conditions are approached via the interaction of the operating physical mechanisms of material deformation, hydrogen diffusion and energy flow. Analytical relations are presented for the distributions of hydrogen concentration in solid solution, hydride volume fraction and stress components, as well as for the hydride precipitation zone boundary. It is shown that there is an annulus, within the hydride precipitation zone, where stresses, although vary according to 1 / r —singularity, deviate significantly from the well-known K-field, being smaller, according to the difference of hydrostatic stress before and after hydride precipitation. The hydride precipitation zone increases with crack-tip constraint, given by T-stress. In addition, temperature gradient affects hydride precipitation zone size, by controlling stress trace distribution. [ABSTRACT FROM AUTHOR]

As an advanced sheet metal processing technology, fine blanking is usually used to produce precision parts for automobiles, aerospace, and other industries, but the forming process consumes huge energy. The previous research on fine blanking has mainly focused on improving the forming quality, but the analysis of process energy consumption from the process perspective is rare. Firstly, the energy consumption of the fine blanking process was analyzed theoretically, and a theoretical model was established. Then, the Ludwik hardening model and Oyane fracture criterion for 16MnCr5 were constructed. Next, the orthogonal experiment was designed to analyze the influence and degree of the main process parameters on surface quality and process energy consumption. Among them, blanking clearance, blank holder type, and blank holder force have the greatest influence on the size of the shear zone, energy consumption of deformation, and total process energy consumption, respectively. Furthermore, the influence mechanism of key process parameters on process energy consumption was deeply revealed from the perspective of deformation area, hydrostatic stress change, and material flow velocity, which provided a theoretical basis for green fine blanking. Finally, the fine blanking experiment was carried out to verify the great difference in surface quality and energy consumption under different process parameter combinations. This paper provides a theoretical direction for the fine blanking process, which can not only get high surface quality but also save energy consumption. [ABSTRACT FROM AUTHOR]

In this article, we propose a robust low‐order stabilization‐free virtual element method on quadrilateral meshes for linear elasticity that is based on the stress‐hybrid principle. We refer to this approach as the stress‐hybrid virtual element method (SH‐VEM). In this method, the Hellinger–Reissner variational principle is adopted, wherein both the equilibrium equations and the strain‐displacement relations are variationally enforced. We consider small‐strain deformations of linear elastic solids in the compressible and near‐incompressible regimes over quadrilateral (convex and nonconvex) meshes. Within an element, the displacement field is approximated as a linear combination of canonical shape functions that are virtual. The stress field, similar to the stress‐hybrid finite element method of Pian and Sumihara, is represented using a linear combination of symmetric tensor polynomials. A 5‐parameter expansion of the stress field is used in each element, with stress transformation equations applied on distorted quadrilaterals. In the variational statement of the strain‐displacement relations, the divergence theorem is invoked to express the stress coefficients in terms of the nodal displacements. This results in a formulation with solely the nodal displacements as unknowns. Numerical results are presented for several benchmark problems from linear elasticity. We show that SH‐VEM is free of volumetric and shear locking, and it converges optimally in the L2$$ {L}^2 $$ norm and energy seminorm of the displacement field, and in the L2$$ {L}^2 $$ norm of the hydrostatic stress. [ABSTRACT FROM AUTHOR]

In this work, the effect of hydrostatic initial stress is studied with the exited semiconductor material. Electrons are exited at the free surface of the elastic semiconductor medium using the photo-thermal-elastic theory during the transport (diffusion) process. The thermal memories are due to the dual-phase-lag (DPL) relaxation times of the heat conduction equation with a novel model. In this model, the thermal conductivity is chosen as a linear dependent function of the thermal temperature impact which is variable. The effect of gravitational field is taken into account during the two-dimensional (2D) elastic deformation under the impact of an internal heat source. The Kirchhoff transformation mapping is used. The harmonic wave (normal mode) method is applied for the 2D governing equations to obtain the main physical fields analytically. Some thermal and mechanical forces are applied with other elastic-plasma conditions at the free surface of the semiconductor material to get the complete solutions. Some comparisons used a novel parameters which depend on the DPL model and the differences in the thermal conductivity parameters and they are illustrated graphically and discussed. [ABSTRACT FROM AUTHOR]

The hydrogen solubility in ferritic and martensitic steels is affected by hydrostatic stress, pressure, and temperature. In general, compressive stresses decrease but tensile stresses increase the hydrogen solubility. This important aspect must be considered when qualifying materials for high‐pressure hydrogen applications (e.g., for pipelines or tanks) by using autoclave systems. In this work, a pressure equivalent for compensating the effect of compressive stresses on the hydrogen solubility inside of closed autoclaves is proposed to achieve solubilities that are equivalent to those in pipelines and tanks subjected to tensile stresses. Moreover, it is shown that the temperature effect becomes critical at low temperatures (e.g., under cryogenic conditions for storing liquid hydrogen). Trapping of hydrogen in the microstructure can increase the hydrogen solubility with decreasing temperature, having a solubility minimum at about room temperature. To demonstrate this effect, the generalized law of the hydrogen solubility is parameterized for different steels using measured contents of gaseous hydrogen. The constant parameter sets are verified and critically discussed with respect to the high‐pressure hydrogen experiments. [ABSTRACT FROM AUTHOR]

In this study, the effects of voids on the deformation behavior and the removal mechanism of amorphous alloys with continuous void structure were revealed by analyzing atomic displacement, cutting forces, and shear strain. The results indicated that shear and extrusion were the main removal mechanisms for amorphous alloys with continuous void structure. The presence of void structures led to a reduction in both the tangential and normal forces and a bigger effect on the normal force than on the tangential force. However, an increase in void diameter causes a decrease in temperature and cutting forces and a reduction formation rate of plastic deformation regions. In addition, it was founded the machining forces and friction coefficients were strongly influenced by the void size comparing with no void workpieces. As the pore size increases, there is a gradual decrease in the friction coefficient. Furthermore, a novel model considering the interaction between the tool and voids was developed to analyze the mechanism of void closure. The model indicated that a faster voids closure and a larger plastic deformation region were observed with an increase of the depth of cut. As the cutting distance increased, the voids were closed due to the machining induced hydrostatic stress. The closure of continuous voids occurred in a similar way without a critical value for the distance and size between voids. Based on the traditional cutting theory, a void processing efficiency formula was established to study the effect of void structure and cutting speeds on the processing efficiency. [ABSTRACT FROM AUTHOR]

Electromigration (EM) is a critical reliability issue in integrated circuits and is becoming increasingly significant as fabrication technology nodes continue to advance. The analysis of the hydrostatic stress, which is paramount in electromigration studies, typically involves solving complex physical equations (partial differential equations, or PDEs in this case), which is time consuming, inefficient and not practical for full-chip EM analysis. In this paper, a novel approach is proposed, conceptualizing circuit interconnect trees as a graph within a graph neural network framework. Using finite element solution software, ground truth hydrostatic stress values were obtained to construct a dataset of interconnected trees with hydrostatic stress values for each node. An improved Graph Convolutional Network (GCN) augmented with edge feature aggregation and attention mechanism was then trained employing the dataset, yielding a model capable of predicting hydrostatic stress values for nodes in an interconnect tree. The results show that our model demonstrated a 15% improvement in the Root Mean Square Error (RMSE) compared to the original GCN model and improved the solution speed greatly compared to traditional finite element software.

This work extends force coupling in the topology optimization of fluid‐structure interaction problems from hydrostatic to total stresses through the inclusion of viscous stress components. The superconvergent patch recovery technique is implemented to remove the discontinuities in velocity derivatives over the finite elements boundaries. The sensitivity analysis is derived analytically for the superconvergent patch recovery approach and further verified through the use of the complex‐step derivative approximation method. Numerical examples demonstrate a differentiation in the optimized designs using pressure versus total stress coupling depending on the flow characteristics of the design problem. [ABSTRACT FROM AUTHOR]

It is frequently emphasized that the action of interfacial adhesion is a critical parameter to improve the stiffness and toughness of polylactic acid/thermoplastic starch (PLA/TS) blends. In this work, the micromechanical behavior of PLA/TS blends with droplet morphology selected from literature is predicted and analyzed systematically by finite element analysis. A quantitative assessment of the effect of interface (perfect or imperfect) on the elastic behavior and craze initiation for toughening of PLA/TS blends is presented. For the elastic behavior, the PLA phase is the blend's load‐bearing component as the TS is more compliant than PLA, so an interface perfectly bonded reduces the blend's elastic modulus when compared to the modulus obtained if the interface is weakly bonded. Regarding the toughening behavior, as a compliant phase, the TS has the potential to nucleate stable crazes in the host PLA matrix independently of the degree of interfacial adhesion because the highly stressed region lies near the equator of the particle; nonetheless, the critical stress for craze initiation is very sensitive to the TS particle size. On the other hand, as the TS is less capable than PLA to develop large hydrostatic stresses, the TS has a low potential to dissipate energy by cavitation. [ABSTRACT FROM AUTHOR]

The propagation of Love-type waves due to an impulsive point source in a hydrostatic stressed transversely isotropic (HSTI) strip clamped between a poroelastic strip and an inhomogeneous semi-infinite elastic half-space is studied. Both the strips are of finite thickness, and the semi-infinite half space is considered spatial-dependent inhomogeneous medium. The Dirac-delta function has been taken into account to represent the impulsive point source force, and Fourier Transform is used to simplify the governing equations for the respective media. Green's functions technique has been adopted for solving the problem using boundary conditions of the considered problem. Thereafter, a closed-form dispersion equation has been obtained for the model. This dispersion equation infers lots of information about the considered wave into the structure. For numerical simulation purposes, we have taken six material examples of a transversely isotropic strip under the hydrostatic stress, namely Beryl, Magnesium, Cadmium, Zinc, Cobalt, and simply isotropic. The impacts of involved parameters on the phase velocity of the wave have been studied extensively and comparatively in 6 numerical examples of HSTI media. It is reported that the phase velocity of the Love-type wave is more pronounced in the presence of porosity, hydrostatic stress, linear and quadratic inhomogeneities as well as the thickness variations in both layers. Both the linear and quadratic enhance the phase velocity of the wave, while the porosity and hydrostatic stress helping to diminish the phase velocity. [ABSTRACT FROM AUTHOR]

Hydrogen as an energy carrier is politically supported and essential for the planned energy turnaround, but requires infrastructure for transport and storage of hydrogen on a large scale, which in turn requires the development of steels resistant to hydrogen‐induced damage. Since the experimental characterization of local hydrogen concentration is nearly impossible, but microstructure level effects are significant for damage initiation, it becomes essential to further develop accompanying numerical evaluation methods. These have to be able to quantitatively describe the effect of nonmetallic inclusions on the local hydrogen concentration as the detrimental effect of nonmetallic inclusions governs the resistance against hydrogen‐induced cracking. To capture this influence, the modeling approaches available in the literature are extended and made usable for tetrahedral elements. Validation is performed using numerical studies with specimens of different stress states. Submodels are exposed to a virtual cooling and then to a hydrogen loading. Based on the resulting residual stress fields, the local hydrogen concentrations around nonmetallic inclusions with different chemical compositions and geometry are investigated and evaluated. Herein, it can be shown that especially the hydrostatic stress has a large influence on the development of the local hydrogen concentration and that the influence is particularly strong for Al2O3‐inclusions. [ABSTRACT FROM AUTHOR]

We first study the plane strain problem associated with an incompressible liquid inclusion having an n-fold axis of symmetry which is embedded in an infinite isotropic elastic matrix subjected to uniform remote hydrostatic stresses. A closed-form solution is derived using Muskhelishvili's complex variable formulation, a four-term conformal mapping function and the application of analytic continuation. The pair of analytic functions characterizing the elastic field in the matrix is completely determined in elementary closed-form. Explicit expressions are obtained and graphically illustrated for the internal uniform hydrostatic stresses within the liquid inclusion and the hoop stress along the liquid–solid interface on the matrix side. The closed-form solution for a linearly compressible liquid inclusion having an n-fold axis of symmetry is also obtained. [ABSTRACT FROM AUTHOR]