Zeitschriftenartikel: „Swelling stresses“

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Bathija, Arpita Pal, Haiyi Liang, Ning Lu, Manika Prasad und Michael Lee Batzle. „Stressed swelling clay“. GEOPHYSICS 74, Nr. 4 (Juli 2009): A47—A52. http://dx.doi.org/10.1190/1.3131385.

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Clay minerals are present in most sedimentary rocks. They find applicability in a wide range of disciplines, such as material, soil, earth, environmental, and biological sciences. Despite their abundance and use, swelling of clays under stress has not received enough scientific attention. We used a two-method approach, consisting of molecular simulation and nanoindentation measurements on montmorillonite. Our analyses of the molecular structure of montmorillonite at various stresses and hydration states showed that swelling behaves in a nonlinear way with stress. Nanoindentation results of Young’s modulus agree with our simulation results, showing the importance of the interlayer in composite clay properties.

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Nah, C., G. B. Lee, C. I. Lim, J. H. Ahn und A. N. Gent. „Swelling of Rubber under Nonuniform Stresses and Internal Migration of Swelling Liquid When the Stresses Are Removed“. Macromolecules 44, Nr. 6 (22.03.2011): 1610–14. http://dx.doi.org/10.1021/ma102528t.

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3

Papanastasiou, Tasos C., Dionissios G. Kiriakidis und Theodore G. Nikoleris. „Extrudate Swelling: Physics, Models, and Computations“. Applied Mechanics Reviews 48, Nr. 10 (01.10.1995): 689–95. http://dx.doi.org/10.1115/1.3005050.

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Viscous, viscoelastic, or elastic normal stresses are superimposed to pressure within flowing fluids. These stresses act normal to the boundaries of the flow that may deform depending on their modulus or viscosity. At absolutely rigid boundaries of infinite modulus of elasticity any boundary deformation and therefore any fluid expansion or swelling is surpressed (eg, flow in rigid pipes, annuli, channels). Elastic boundaries (eg, flow in veins and arteries, flow by membranes, around inflating/deflating balloons) deform under the action of normal stresses, allowing expansion or swelling of fluid. The same mechanism prevails in lubrication, where pressure and superimposed normal viscoelastic stresses keep surfaces in relative motion apart, with simultaneous increase in load capacity. Viscous boundaries (eg, liquid jet in air or in immiscible liquid, slow extrusion of viscoelastic liquids from dies, expanding/collapsing air-bubbles or liquid-droplets) are displaced by flowing adjacent immiscible fluids, allowing swelling or imposing contraction depending on relative rheological characteristics. Thus, the kind of swelling examined here is independent of density, ie, incompressible, and is due to the action of normal stresses against the boundary that is imposed either by adjacent deformable obstacles or else by surface tension. The resulting swelling is dynamic (ie, it initiates, changes and ceases with the flow) and can be made permanent by solidification, crystallization or glassification. The most profound form of incompressible swelling is the extrude swelling that controls the ultimate shape of extruded parts. Incompressible swelling is enhanced by the ability of macromolecules to deform and recover (eg, viscoelastic) and by the design of flow conduits to impose sharp transitions of deformation modes (eg, singular exit flows). The same swelling is reduced by the ability of molecules (or fibers in fiber-suspensions) to align with the flow streamines, as well as any tendency of solid-like structure formulation (eg, viscoplastic).

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Khrapatova, I. V., und O. V. Krotov. „THE ANALYSIS OF THE STRESS-STRAIN STATE OF THE SYSTEM «BASEMENT - PILE FOUNDATION – STRUCTURE» CONSIDERING SWELLING PROPERTIES OF SOILS“. ACADEMIC JOURNAL Series: Industrial Machine Building, Civil Engineering 2, Nr. 49 (17.10.2017): 54–60. http://dx.doi.org/10.26906/znp.2017.49.824.

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This work analyzes factors affecting swelling soils and presents a calculation algorithm of structure on swelling soils base for the plane problem. In this work an analysis of the factors influencing the swelling of soils is made, the algorithm for calculating the structure with the base with swellable soils for a plane problem is given. At the same time, the swelling process is considered as an additional influence, close in nature to temperature, and the swelling soil is considered a material having orthotropic properties. The value of the relative swelling depends on the level of the stress state, while the value of the main stresses is compared with the magnitude of the pressure of swelling. Therefore, to determine the deformation characteristics of the swelling soil, several variants of the stressed state of the soil have to be considered. The effectiveness of the obtained solution has been verified according to the example for pile foundations.

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Makhnenko, O. V., I. V. Mirzov und V. B. Porokhonko. „Modelling of residual stresses, radiation swelling and stressed state of in-service WWER-1000 reactor baffle“. Paton Welding Journal 2016, Nr. 4 (28.04.2016): 32–38. http://dx.doi.org/10.15407/tpwj2016.04.03.

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6

Hall, M. M. „Irradiation creep relaxation of void swelling-driven stresses“. Journal of Nuclear Materials 432, Nr. 1-3 (Januar 2013): 166–74. http://dx.doi.org/10.1016/j.jnucmat.2012.08.015.

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7

Kowalski, Stefan J., und Andrzej Rybicki. „Drying Induced Stresses in a Swelling Porous Wall“. Transport in Porous Media 57, Nr. 1 (Oktober 2004): 35–48. http://dx.doi.org/10.1023/b:tipm.0000032743.55654.ed.

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8

Kowal, M., und S. J. Kowalski. „Experimental Investigation of Water Soaked Wood at Uniaxial and Biaxial States of Stress“. Applied Mechanics Reviews 48, Nr. 10 (01.10.1995): 684–88. http://dx.doi.org/10.1115/1.3005049.

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It is possible to observe a significant difference in swelling strains of unstressed and stressed water soaked wood. This paper points out that the swelling strains depend not only on the magnitude of stress in wood but also on the kind of stress state. Our main aim is to investigate the relation between various states of stress and the swelling strains in water soaked wood. Three different states of stress are studied: tension in the radial direction, compression in the tangential direction with respect to the growth rings, and both these stresses acting together (biaxial stress). Some weighty conclusions follow from the investigations. The main one is that, although the mechanical strains alone are negligibly small compared to the free swelling strains, the coupled mechanical-swelling strains, being a function of the stress state and the moisture content, have a great significance in total strains of water soaked wood.

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Breslavsky, Dmytro. „Influence of stresses on deformation process under the irradiation creep and swelling“. Bulletin of the National Technical University «KhPI» Series: Dynamics and Strength of Machines, Nr. 2 (31.12.2021): 23–28. http://dx.doi.org/10.20998/2078-9130.2021.2.245529.

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Approaches for describing the deformation of structural elements made from the material, in which radiation creep and swelling strains develop simultaneously, are discussed. The technique for description of irradiation swelling strains, which is used for calculational analysis of stress-strain state arising in structural elements under the joint action of irradiation and thermal-stress fields, is regarded. A complete system of equations of the boundary –initial value problem is presented, in which elastic and thermal strains, strains of radiation creep and swelling are taken into account. Numerical modelling was carried out using the specialized software FEM Creep, in which the boundary value problem is solved by the Finite Element Method, and the initial one is integrated in time by the difference predictor-corrector method. Two forms are given for the equation of state describing the radiation swelling strains: first is for the components of the strain tensor as well as second is prepared for their rates. The hypothesis about the linear correspondence of the received radiation dose and the deformation time, during which radiation swelling strains develop, are analyzed. A number of questions that require answers when using equations with a complex stress state in which the radiation swelling strains are directly depend on stresses, are discussed. Based on the processing of experimental data on the swelling of tubes made of steel 316Ti in the temperature range of 450-460 °С, a form of the equation for the radiation swelling strain rate is proposed, and the constants included in it are determined. Using the example of numerical modelling of the deformation of tubes were made of steel 316Ti and loaded by inner pressure, the applicability of the classical approach for the analysis of the stress-strain state in the presence of radiation swelling strains is shown.

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Virta, Jari, Simo Koponen und Ilmari Absetz. „Measurement of swelling stresses in spruce (Picea abies) samples“. Building and Environment 41, Nr. 8 (August 2006): 1014–18. http://dx.doi.org/10.1016/j.buildenv.2005.10.012.

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11

Richards, BG. „The role of lateral stresses on soil water relations in swelling clays“. Soil Research 24, Nr. 4 (1986): 457. http://dx.doi.org/10.1071/sr9860457.

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The moisture characteristic of a swelling soil is the result of complex interaction between the soil water potential and imposed mechanical stresses. This can give rise to soil water profiles which cannot be interpreted by soil water theories for non-swelling soils. Agricultural soil physics has been concerned primarily with highly structured surface soils, and has developed simple theories for the effects of stress on soil water relations in swelling soils. These simple theories ignore the effect of lateral stress in the soil. Civil engineers, on the other hand, dealing mainly with less complex soils at depth, have developed more complex theories for the effect of three-dimensional stress states on soil water relations. This paper shows how the effect of three-dimensional stress can and should be included in soil water studies of swelling soils, and gives examples to demonstrate the possible magnitude of such effects.

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Sambale, Anna Katharina, Michael Stanko, Jessica Emde und Markus Stommel. „Characterisation and FE Modelling of the Sorption and Swelling Behaviour of Polyamide 6 in Water“. Polymers 13, Nr. 9 (04.05.2021): 1480. http://dx.doi.org/10.3390/polym13091480.

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Polyamide 6 (PA6) is known to absorb water from its environment due to its chemical structure. This water absorption leads to a change in the mechanical properties as well as an increase in volume (swelling) of the polyamide. In the present work, the sorption and swelling behaviour of polyamide 6 in different conditioning environments was experimentally investigated on different part geometries to develop a finite element (FE) method on the basis of the measured data that numerically calculates the sorption and swelling behaviour. The developed method includes two analyses using the Abaqus software. Both the concentration-dependent implementation of the simulation parameters and the calculation of swelling-induced stresses are performed. This enables the modelling of the sorption curves until maximum saturation is reached and the simulation of the characteristic S-shaped swelling curves. Therefore, the developed methodology represents an efficient method for predicting the sorption and swelling behaviour of polyamide 6 parts during conditioning in a water bath. The determined properties provide the basis for the development of an FE-based simulation environment to take moisture absorption into account during the part design. This enables the calculation of moisture-induced swelling processes and the resulting initial stresses in a given part.

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Fusaro, Robert E., Andrew D. Graham, Reuben K. Rivera, Lan-Anh Nguyen und Kenneth A. Polse. „OVERNIGHT CORNEAL SWELLING RESPONSE TO LOW AND MODERATE HYPOXIC STRESSES“. Optometry and Vision Science 72, SUPPLEMENT (Dezember 1995): 88. http://dx.doi.org/10.1097/00006324-199512001-00139.

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Toscano, Andrea, Giuseppe Pitarresi, Michele Scafidi, Maria Di Filippo, Giuseppe Spadaro und Sabina Alessi. „Water diffusion and swelling stresses in highly crosslinked epoxy matrices“. Polymer Degradation and Stability 133 (November 2016): 255–63. http://dx.doi.org/10.1016/j.polymdegradstab.2016.09.004.

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Makhnenko, O. V., I. V. Mirzov und V. B. Porokhonko. „Modelling of residual stresses, radiation swelling and stressed state of in-service WWER-1000 reactor baffle“. Автоматическая сварка 2016, Nr. 4 (28.04.2016): 35–41. http://dx.doi.org/10.15407/as2016.04.03.

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16

Wangler, Timothy, und George W. Scherer. „Clay swelling inhibition mechanism of α,ω-diaminoalkanes in Portland Brownstone“. Journal of Materials Research 24, Nr. 5 (Mai 2009): 1646–52. http://dx.doi.org/10.1557/jmr.2009.0190.

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Many clay-bearing sedimentary stones such as Portland Brownstone will swell when exposed to water, and this can generate damaging stresses as differential strains evolve during a wetting cycle. Current swelling inhibitors, consisting of α,ω-diaminoalkanes, can reduce swelling in Portland Brownstone up to 50%. In this study, through x-ray diffraction and swelling strain experiments, we demonstrate that the α,ω-diaminoalkanes inhibit swelling by substituting for interlayer cations and partially hydrophobicizing the interlayer, then rehydrating on subsequent wetting cycles. We also introduce the copper (II) ethylenediamine complex as a potential treatment for swelling inhibition.

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Graham, J., F. Saadat, M. N. Gray, D. A. Dixon und Q. Y. Zhang. „Strength and volume change behaviour of a sand–bentonite mixture“. Canadian Geotechnical Journal 26, Nr. 2 (01.05.1989): 292–305. http://dx.doi.org/10.1139/t89-038.

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Triaxial and one-dimensional swelling tests have been performed at pressures up to 3 MPa on a compacted sand–bentonite mixture with potential use for containing nuclear and other toxic wastes. The material expands in a low stress range up to 0.6 MPa, with the volumetric expansion depending on the confining pressure and the duration of the tests. Swelling is inhibited by confining pressures in excess of 0.8 MPa. The strength of the material corresponds to that of the bentonite fraction. The material is dilatant at low stresses (below about 0.8 MPa) and compressive at higher stresses. Normalized bulk moduli are significantly affected by stress level, whereas normalized tangent shear moduli at 0.5qmax decrease with increasing confining stresses. The data suggest a modified critical state model for the stress–strain–time behaviour of the material. Key words: bentonite, sand–bentonite, mixtures, compaction, triaxial, strength, compressibility, critical state, nuclear waste, containment.

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Alessi, Sabina, Andrea Toscano, Giuseppe Pitarresi, Clelia Dispenza und Giuseppe Spadaro. „Water diffusion and swelling stresses in ionizing radiation cured epoxy matrices“. Polymer Degradation and Stability 144 (Oktober 2017): 137–45. http://dx.doi.org/10.1016/j.polymdegradstab.2017.08.009.

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Khattra, N. S., M. H. Santare, A. M. Karlsson, T. Schmiedel und F. C. Busby. „Effect of Water Transport on Swelling and Stresses in PFSA Membranes“. Fuel Cells 15, Nr. 1 (16.12.2014): 178–88. http://dx.doi.org/10.1002/fuce.201400058.

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Modenesi, Paolo, Massimo Piana, Paolo Giordani, Alessandra Tafanelli und Antonella Bartoli. „Calcium Oxalate and Medullary Architecture in Xanthomaculina Convoluta“. Lichenologist 32, Nr. 5 (September 2000): 505–12. http://dx.doi.org/10.1006/lich.2000.0276.

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AbstractThe anatomy of Xanthomaculna convolute shows adaptation to a vagrant life form and to the moisture conditions of its habitat. The differential swelling of the irregularly thickened upper cortex and the medulla, in addition to the rigid medullary structure, due to the deposition of calcium oxalate, allow orderly hygroscopic thalline movements. The architecture of the medulla appears to be closely related to masonry-like arches where the material is only stressed by compression and the stresses are distributed at the hinges. The possible role of crystalline medullary deposition as a radiation reflector is also suggested.

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Hawlader, B. C., Y. N. Lee und K. Y. Lo. „Three-dimensional stress effects on time-dependent swelling behaviour of shaly rocks“. Canadian Geotechnical Journal 40, Nr. 3 (01.06.2003): 501–11. http://dx.doi.org/10.1139/t03-006.

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This paper presents a time-dependent constitutive model that has been developed for the swelling of shaly rocks. Laboratory test results on many shales, including Queenston shale, show that the swelling of these rocks depends on the applied stresses. The applied stress in one principal stress direction reduces swelling strain not only in that direction but also in the perpendicular directions. It was found that swelling strain reductions are nonlinearly dependent on applied stress. The reduction in lateral swelling caused as a result of axial stress is modeled using the "pseudo-Poisson's effect". The proposed model is used to simulate the development of swelling strain with time under uniaxial and biaxial stress conditions. Comparison between the computed and experimental results shows that the pseudo-Poisson's effect is a key parameter for simulating the observed time-dependent swelling.Key words: swelling, Queenston shale, modeling, three-dimensional stress effect, nonlinearity.

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Baltodano-Goulding, Rafael. „Swelling Curve in Terms of Effective Stress for Expansive Clays“. E3S Web of Conferences 195 (2020): 02023. http://dx.doi.org/10.1051/e3sconf/202019502023.

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Expansive soils can present an unsaturated state where the soil exhibits volume changes due to both moisture variations that change the state of stresses and moisture variations that interact with its mineralogical characteristics. These special kinds of soils are normally clay type soils that had suffered isomorphous substitution creating a charge imbalance of the clay mineral crystals. This imbalance promotes the trapping of water molecules by the clay particles. It is commonly assumed that a high plasticity index can be an indication of a clay´s high swell potential. However, in arid regions, it is possible to have clays with very high swell potential and low plasticity indexes due primarily to a decrease in the state of effective stress, which will produce expansion of the material. It is common practice to study the swelling characteristics of these soils by performing free-swell tests that can be used for designing removal and replacement backfills or drilled shafts. However, the expansion percentage obtained from this type of test is actually in terms of total stresses and not in terms of effective stress, as it is commonly assumed. Moreover, it is highly dependent on the magnitude of the preload used. This paper presents some efforts made to obtain the swelling part of the curve in terms of effective stresses from the traditional free-swell test. It was hypothesized that the shape of this curve could either have the shape of the rebound curve from a saturated consolidation test or a shape similar to the soil-water characteristic curve.

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SATO, Haruo, und Masaki FUKAZAWA. „A Thermodynamic Analysis on the Swelling Stress of Na-Bentonite under Various Solution Conditions“. MRS Advances 1, Nr. 61 (2016): 4019–25. http://dx.doi.org/10.1557/adv.2017.184.

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ABSTRACTThe swelling stress of bentonite which is one of the engineered barriers and backfill materials for radioactive waste disposal is strongly dependent on water chemistry such as saline water. The authors have developed a thermodynamic model for calculating the swelling stress (pressure) of bentonite, based on the thermodynamic data of interlayer water in Na-montmorillonite obtained in earlier studies. In this work, the swelling stress of water-saturated Na-bentonite was calculated for various bentonite dry densities and solution conditions such as sodium chloride concentration and nitrate concentration and compared to the measured data.Swelling stress versus montmorillonite partial density was estimated for solutions containing sodium chloride ([NaCl] = 0−3.4 m, m: molality) and nitrate concentrations ([NaNO3] = 0−6 m) and compared to data measured for bentonites with various montmorillonite contents and silica sand contents. The calculated swelling stresses commonly decreased with increasing [NaCl] and [NaNO3] for the same montmorillonite partial density. The trend of swelling stress versus [NaCl] was in a good agreement with the measured results. The calculated swelling stress versus [NaCl] was also quantitatively in a good agreement within the scattering of the measured data. The trend versus [NaNO3] was also similar to that versus [NaCl]. However, the calculated results were quantitatively different from the measured data ([NaNO3] = 3, 5 m, montmorillonite partial density = 0.76−0.87 Mg/m3). Even though those measurements were conducted under the condition of high ionic strength, the measured data of swelling stresses were almost the same as in the condition of distilled water. Since the measurement periods were quite rather short, it is conceivable that the measurements were not done at equilibrium.

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Sanders, J. E., J. M. Greve, C. Clinton und B. J. Hafner. „Clinical study: Changes in interface pressure and stump shape over time: Preliminary results from a transtibial amputee subject“. Prosthetics and Orthotics International 24, Nr. 2 (August 2000): 163–68. http://dx.doi.org/10.1080/03093640008726539.

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Interface stresses and stump shape were measured during sessions over a twomonth interval on a transtibial amputee subject. Results from thirteen transducer sites monitored during four sessions showed greater interface pressure changes over time at anterior sites than at lateral or posterior locations. There was a trend of decreased pressure with stump swelling and increased pressure for stump atrophy. During one session in which stump shape was monitored over a 23.1 min interval after ambulation, stump swelling was localised. Swelling tended to increase in the regions of initial enlargement, as opposed to redistributing through different areas over time. Regions of swelling were anterior lateral and posterior proximal, areas of thick underlying soft tissue. Identification of localised areas of swelling and atrophy and understanding of their effects on interface pressures could be used to improve individual socket design.

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Berre, Toralv. „Effect of sample disturbance on triaxial and oedometer behaviour of a stiff and heavily overconsolidated clay“. Canadian Geotechnical Journal 51, Nr. 8 (August 2014): 896–910. http://dx.doi.org/10.1139/cgj-2013-0077.

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The tests in this investigation were performed on a natural soft clay with plasticity index around 32%, which was K0 consolidated to a vertical stress of 2942 kPa and then K0 unloaded to a vertical stress of 74 kPa (i.e., to the “in situ” stress). The specimens so created were disturbed in various ways to study the effect of sample disturbance on the stress–strain relationships during undrained shearing and during drained K0 loading (i.e., K0 triaxial and oedometer tests). The results for two testing alternatives may be summarized as follows. Alternative 1: Allow the specimen to swell at the correct in situ effective stresses, but accept an initial water content that is higher than the in situ value. This alternative was found to give the best stress–strain relationships around the in situ effective stresses for undrained triaxial tests, but with undrained shear strength values up to about 20% too low, due to the swelling taking place during consolidation to the in situ effective stresses. Alternative 2: Prevent swelling by starting the test at effective stresses that are higher than the in situ stresses, but with a water content that is closer to the in situ value than if alternative 1 is chosen. Using only isotropic stresses prior to shearing, this alternative was found to give better undrained shear strength values (although up to about 14% too high) but strain values much too small around the in situ effective stresses. For oedometer tests, only alternative 2 was investigated. Also, for these tests, the strains around the in situ stress were too small, but preconsolidation stresses estimated from stress–strain curves were typically only around 60% of the true value.

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Lu, Yu, Wei-Min Ye, Qiong Wang, Yuan-Hong Zhu, Yong-Gui Chen und Bao Chen. „Anisotropic swelling behaviour of unsaturated compacted GMZ bentonite hydrated under vertical stresses“. Bulletin of Engineering Geology and the Environment 80, Nr. 7 (05.05.2021): 5515–26. http://dx.doi.org/10.1007/s10064-021-02261-y.

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Fu, T. Z., C. J. Durning und H. M. Tong. „Simple model for swelling-induced stresses in a supported polymer thin film“. Journal of Applied Polymer Science 43, Nr. 4 (20.08.1991): 709–21. http://dx.doi.org/10.1002/app.1991.070430408.

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Hahn, H. T. „Hygrothermal Damage in Graphite/Epoxy Laminates“. Journal of Engineering Materials and Technology 109, Nr. 1 (01.01.1987): 3–11. http://dx.doi.org/10.1115/1.3225930.

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The use of micromechanics equations for moisture diffusivity shows that the in situ diffusivity is slightly lower than the bulk diffusivity for matrix resins, thereby indicating absence of any matrix damage in virgin composites. When exposed to hygrothermal environments, however, composites undergo degradation which manifests itself in anomalous moisture diffusion behavior and reduced structural performance. The hygrothermal degradation is the result of matrix plasticization, microvoid formation, and microcracking. The time dependence of plasticization as well as the tensile stress resulting from steep moisture gradient is responsible for the damage induced by thermal spiking of wet composites. Swelling of neat resins is frequently less than predicted by the volume additivity. A simple micromechanics analysis provides a good estimate of composite swelling strain from resin properties. The bilinearity and the hysteresis observed in relations between swelling and moisture content are attributed to the existence of a threshold moisture concentration below which swelling is negligible. Relaxation of residual stresses is a long-term process under nonhostile environments. However, it is accelerated considerably around and above the glass transition temperature. The fast stress relaxation can change the transverse ply stress from compressive to tensile after thermal spiking, thereby inducing ply cracking and accelerating the subsequent moisture absorption. How residual stresses can affect ply cracking and delamination is shown through a fracture mechanics analysis.

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Wang, Yang, Jun Teng, Qi Huang, Wei Wang und Zhenyang Ren. „Insight on the Void Ratio–Suction Relationship of Compacted Bentonite during Hydration“. Materials 15, Nr. 15 (26.07.2022): 5173. http://dx.doi.org/10.3390/ma15155173.

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Investigation on swelling characteristics of buffer/backfill materials during hydration is an important issue in the design of artificial barriers in high-level radioactive waste (HLW) disposal repositories. In this work, for clarifying the characteristic of void ratio–suction relationship for compacted bentonite on hydration path, suction-controlled swelling deformation tests under constant vertical stresses 0.001~40 MPa were carried out on compacted bentonite specimens. Four different types of void ratio-suction curves indicated that swelling-collapse behavior under hydration depends on suction and over-consolidation ratio (OCR), based on which the swelling index was defined. Then, equations were proposed for describing the swelling-collapse characteristic of void ratio–suction curves. Simulation results of suction-controlled swelling deformation tests show that the different types of the hydration deformation curves could be well described by the proposed equations. Obviously, the proposed equations could be used for description and prediction of swelling characteristics of compacted bentonite during hydration, which is also of great importance for the safety assessment of the HLW repositories.

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Li, Lili, Xiaofei Shan, Zhiying Luo, Wenwen Liu, Jianxia Liu, Jianfang Yu, Zhangjing Chen und Ximing Wang. „Analysis of Deformation Fixation of Thermally Compressed Scots Pine (Pinus sylvestris L.)“. Forests 15, Nr. 5 (11.05.2024): 842. http://dx.doi.org/10.3390/f15050842.

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Heat treatment effectively inhibits the water absorption recovery of compressed wood. To elucidate this phenomenon, we prepared compressed pine and thermally compressed pine (heartwood and sapwood) using the hot pressing method at 160 °C, 180 °C, 200 °C, and 220 °C. The effects of chemical components, swelling stresses, and monosaccharides on modified wood recovery were investigated using regression analyses. Notably, the recovery of both compressed heartwood and sapwood during water absorption declined from 18.89% to 2.66% and from 58.40% to 1.60%, respectively, after heat treatment. Similarly, the swelling stresses of the compressed heartwood and sapwood at 220 °C, respectively, ranged from 0.693 MPa to 0.275 MPa and from 0.783 MPa to 0.330 MPa. These were close to the values of untreated heartwood (0.175 MPa) and sapwood (0.225 MPa). Regression functions indicated that the recovery of compressed wood is chemically dependent on hemicellulose and mechanically related to swelling stress. For monosaccharides, regression functions indicated that modified heartwood recovery primarily relied on mannose, whereas modified sapwood recovery was remarkably affected by mannose and xylose. This confirmed that the pyrolytic monosaccharides in hemicellulose promoted stress relaxation, which induced the deformation fixation of thermally compressed wood.

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Dušek, Karel, und Miroslava Dušková-Smrčková. „Volume Phase Transition in Gels: Its Discovery and Development“. Gels 6, Nr. 3 (31.07.2020): 22. http://dx.doi.org/10.3390/gels6030022.

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The history of volume phase transition of responsive gels from its theoretical prediction to experimental discovery was described and the major role of mixing Gibbs energy function in theoretical models was stressed. For detailed analysis and fine tuning of the volume phase transition, the generalized Flory–Huggins model with concentration and temperature dependent interaction function coupled with Maxwell construction as a tool is very suitable. Application of expansive stresses can uncover the potential of various swelling gels for volume phase transition. Experimentally, the abrupt, equilibrium-controlled phase transition is often hard to achieve due to passage of gel through states of mechanical instability and slow relaxation processes in macroscopic objects.

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Graham, J., J. M. Oswell und M. N. Gray. „The effective stress concept in saturated sand–clay buffer“. Canadian Geotechnical Journal 29, Nr. 6 (01.12.1992): 1033–43. http://dx.doi.org/10.1139/t92-121.

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Uncertainty has existed about the applicability of the effective stress concept to dense, compacted, plastic clays. To examine this, a series of tests has been performed on mixtures of sand and bentonite. Specimens were made by combining equal weights of the dry components with water and compacting the mixture to 85 or 95% ASTM Modified maximum dry density. The tests investigated the proposition that the behaviour of the mixture can be expressed in terms of effective stresses defined as the tensor difference between externally applied total stresses and pore-water pressures measured outside the cell. The proposition cannot be examined directly, but must be studied through a series of corollaries, that is, statements of behaviour that would be expected if the proposition were true. The testing considered the behaviour of specimens in consolidation and shear. Effective consolidation pressures were from 0.3 to 3.0 MPa, with back pressures from 0.2 to 7.0 MPa. Within acceptable bounds of experimental error, the tests show that effective stresss can be used to describe consolidation and shear behaviour. However, because part of the effective stress in the clay is derived from net interparticle repulsive (unit) forces seated in diffuse double layers around aggregations of bentonite particles, the applicability of the concept has at this stage been restricted to conditions of constant volume (or possibly constant straining rate), constant chemistry, and constant temperature. Key words : clay, plastic clay, expansive clay, bentonite, effective stress, triaxial, swelling pressure, swelling equilibrium.

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Griffiths, Malcolm, Steven Xu und Juan Eduardo Ramos Nervi. „Swelling and He-Embrittlement of Austenitic Stainless Steels and Ni-Alloys in Nuclear Reactors“. Metals 12, Nr. 10 (10.10.2022): 1692. http://dx.doi.org/10.3390/met12101692.

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Rate theory models have been developed for the swelling and He-embrittlement of austenitic stainless steels and Ni-alloys in nuclear reactors. The models illustrate how microstructure evolution during irradiation affects the rate of change of mechanical properties and the dimensional stability. He-stabilised cavity accumulation on grain boundaries, which causes brittle failure at low stresses and strains known as He-embrittlement, is shown to be strongly dependent on the irradiation temperature and the rate of production of Frenkel pairs and He atoms. The results show that the accumulation of cavities on grain boundaries falls into two regimes: (i) that dictated by matrix bubble swelling at low temperatures; and (ii) that dictated by matrix void swelling at high temperatures.

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Al-Juari, Khawla A. „Volume Change Measurement of Collapsible Soil Stabilized with Lime and Waste Lime“. Tikrit Journal of Engineering Sciences 16, Nr. 3 (30.09.2009): 38–54. http://dx.doi.org/10.25130/tjes.16.3.04.

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This paper presents a series of laboratory tests to evaluate the effects of lime and waste lime on the volume change and strength characteristics of moderately collapsible soil selected from Al-Rashidia in Mosul city. The tests are performed at different percentages of lime and waste lime of 0, 0.25, 0.5, 1.0, 2.0, 3.0, 4.0, 6.0 and 8.0% by dry weight of soil. One dimensional compression tests are conducted to clarify the influences of relative compaction, compaction water content, vertical stress level and curing time on the volume change and strength characteristics. The results of this study indicated a decrease in the plasticity, swelling potential and swelling pressure of treated soil. The soil became non-plastic at (3&6)% of lime and waste lime respectively. Swelling pressure and swelling potential reached to zero at 2% lime and 2&7 days of curing time. Unconfined compressive strength (UCS) reached to maximum value at optimum stabilizers content. The UCS of lime treated soil is more than that treated by waste lime at different curing time. The collapse index and potential of treated soil are found less than that of natural soil and decrease with increasing stabilizer content until drop to zero at 2% lime. Collapsing increased continuously with applied stresses, but with curing time reached a maximum value at 2 day. On the other hand, collapsing of treated soil with lime is less than that of waste lime treated soil at different curing time and stresses.

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Hawlader, B. C., K. Y. Lo und I. D. Moore. „Analysis of tunnels in shaly rock considering three-dimensional stress effects on swelling“. Canadian Geotechnical Journal 42, Nr. 1 (01.02.2005): 1–12. http://dx.doi.org/10.1139/t04-083.

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Underground structures in shales or shaly rocks endure time-dependent swelling effects. Laboratory test results show that the swelling of these shales is dependent on three-dimensional stresses; an external stress on a specimen in one principal direction reduces the swelling not only in that direction but also perpendicularly. The effectiveness of a time-dependent swelling model that considers the three-dimensional stress effect is presented in this paper. A finite element algorithm incorporating the new constitutive model is used for a numerical analysis. The finite element program is used to analyze two tunnels in southern Ontario: the Heart Lake storm sewer tunnel, and the Darlington cold-water intake tunnel. The predicted results agree well with the records of field performance of these tunnels. The comparison between present analyses and the existing closed-form solution shows that the existing solution overestimates the time-dependent swelling effects. The three-dimensional stress effects on swelling are not considered in the closed-form solutions and are the cause of this discrepancy. The pseudo-Poisson's effect is a key parameter for modelling the observed time-dependent swelling. The use of these solutions in design is discussed.Key words: time-dependent swelling, shale, modelling, three-dimensional stress effect, finite element method, tunnel.

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Steiner, W. „Swelling rock in tunnels: Rock characterization, effect of horizontal stresses and construction procedures“. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 30, Nr. 4 (August 1993): 361–80. http://dx.doi.org/10.1016/0148-9062(93)91720-4.

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Furtak, K. „Assessment of Shear Stresses from Shrinkage and Thermal Deformation in Wood-Concrete Bridge Beams“. Archives of Civil Engineering 65, Nr. 4 (01.12.2019): 37–50. http://dx.doi.org/10.2478/ace-2019-0045.

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AbstractThe aim of the paper is to assess the values of shear (delaminating) stress in the composition plane between the concrete (RC) deck slab and wood girder from concrete shrinkage, and shrinkage and swelling of wood, as well as difference in temperature between the wood web and concrete slab.

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Gent, A. N., J. A. Hartwell† und Ginger Lee. „Effect of Carbon Black on Crosslinking“. Rubber Chemistry and Technology 76, Nr. 2 (01.05.2003): 517–32. http://dx.doi.org/10.5254/1.3547758.

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Abstract For a number of different vulcanization systems, the equilibrium swelling ratios for carbon-black-filled and unfilled samples are shown to be linearly related, as found by Lorenz and Parks, indicating that the degree of crosslinking is not changed by incorporating carbon black. However, filled compounds swell less, and thus the apparent degree of crosslinking is significantly greater. For example, it is about twice as large for compounds containing 50 phr of HAF carbon black. This is confirmed by measurements of the elastic modulus of swollen samples. Relatively strong bonds appear to be formed between rubber molecules and the surface of carbon black particles - bonds that can withstand swelling stresses and temperatures of up to 120 °C. Bonding between rubber and carbon black is also indicated by the limited swelling of filled rubber compounds even before vulcanization, although in this case the apparent degree of crosslinking is smaller. Thus, vulcanization appears to enhance the contribution of rubber-particle bonding to the elastic modulus and restricted swelling of carbon-black-filled vulcanizates. Simple procedures are suggested for estimating the actual degree of crosslinking in filled rubber vulcanizates from measurements of equilibrium swelling or elastic modulus.

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Lanir, Yoram. „Plausibility of Structural Constitutive Equations for Swelling Tissues—Implications of the C-N and S-E Conditions“. Journal of Biomechanical Engineering 118, Nr. 1 (01.02.1996): 10–16. http://dx.doi.org/10.1115/1.2795935.

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The mechanically important constituents of swelling tissues are fibers embedded in an osmotically active fluid. The tissues’ response to external loading is the sum of contribution of the axial stresses in the fibers and of the fluid pressure. The fluid osmotic properties play a key role in determining its equilibrium response. The present study examines the conditions under which the elastic response of tissues as modeled by structural constitutive equations, is thermodynamically plausible. The analysis shows that plausibility is ensured if the fibers’ axial force increases monotonically with stretch and if the fluid osmotic pressure increases convexly with concentration. Published data shows that both conditions prevail in swelling tissues. Plausibility considerations seem to pose no specific restrictions on the structure of the tissues’ fibrous network. It is thus concluded that in swelling tissues, structural constitutive formulation is compatible with thermodynamically plausible response.

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Pitarresi, Giuseppe, Michele Scafidi, Sabina Alessi, Maria Di Filippo, Claude Billaud und Giuseppe Spadaro. „Absorption kinetics and swelling stresses in hydrothermally aged epoxies investigated by photoelastic image analysis“. Polymer Degradation and Stability 111 (Januar 2015): 55–63. http://dx.doi.org/10.1016/j.polymdegradstab.2014.10.019.

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Jim, C. Y. „Experimental study of soil microfabrics induced by anisotropic stresses of confined swelling and shrinking“. Geoderma 37, Nr. 2 (März 1986): 91–112. http://dx.doi.org/10.1016/0016-7061(86)90024-8.

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Dudarev, Sergei L., Daniel R. Mason, Edmund Tarleton, Pui-Wai Ma und Andrea E. Sand. „A multi-scale model for stresses, strains and swelling of reactor components under irradiation“. Nuclear Fusion 58, Nr. 12 (14.09.2018): 126002. http://dx.doi.org/10.1088/1741-4326/aadb48.

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Smiles, D. E. „Hydrology of swelling soils: a review“. Soil Research 38, Nr. 3 (2000): 501. http://dx.doi.org/10.1071/sr99098.

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A generally accepted theory of liquid flow in rigid systems has been used in soil science for more than 50 years. Liquid flow in systems that change volume with liquid content is not so well described and remains a major challenge to soil scientists, although its application in chemical and mining engineering and soil mechanics is increasingly accepted. Theory of water flow in swelling soils must satisfy material continuity. It must also account for changes in the gravitational potential energy of the system during swelling and for anisotropic stresses that constrain the soil laterally but permit vertical movement. A macroscopic and phenomenological analysis based on material balance and Darcy’s law is the most useful first approach to water flow and volume change in such soils. Use of a material coordinate based on the solid distribution results in a flow equation analogous to that L. A. Richards enunciated for non-swelling soils. This framework is strain-independent and solutions to the flow equation exist for a wide range of practically important conditions. The approach has been well tested in clay suspensions and saturated systems such as mine tailings and sediments. It is also applied in soil mechanics. This paper reviews central elements in application of the analysis to swelling soils. It argues that, as with use of the Richards’ equation in rigid soils, complexities are evident, but the approach remains the most coherent and profitable to support current need and future research. The use of material coordinates, to ensure material balance is assessed correctly, is simple.

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Demirkoparan, Hasan, und Jose Merodio. „Bulging bifurcation of inflated circular cylinders of doubly fiber-reinforced hyperelastic material under axial loading and swelling“. Mathematics and Mechanics of Solids 22, Nr. 4 (06.09.2015): 666–82. http://dx.doi.org/10.1177/1081286515600045.

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In this paper, we examine the influence of swelling on the bulging bifurcation of inflated thin-walled cylinders under axial loading. We provide the bifurcation criteria for a membrane cylinder subjected to combined axial loading, internal pressure and swelling. We focus here on orthotropic materials with two preferred directions which are mechanically equivalent and are symmetrically disposed. Arterial wall tissue is modeled with this class of constitutive equation and the onset of bulging is considered to give aneurysm formation. It is shown that swelling may lead to compressive hoop stresses near the inner radius of the tube, which could have a potential benefit for preventing aneurysm formation. The effects of the axial stretch, the strength of the fiber reinforcement and the fiber winding angle on the onset of bifurcation are investigated. Finally, a boundary value problem is studied to show the robustness of the results.

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Derrien, Katell, und Pierre Gilormini. „Interaction between Stress and Diffusion in Polymers“. Defect and Diffusion Forum 258-260 (Oktober 2006): 447–52. http://dx.doi.org/10.4028/www.scientific.net/ddf.258-260.447.

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When moisture uptake in a polymer is associated with swelling, it induces stresses which interact with the entire diffusion process. This coupling is addressed in this paper, which extends immediately to the diffusion of other fluids, like solvents. First, the generalized chemical potential is used to analyze the effect of stresses on the moisture capacity of polymers, and a relation is derived as a function of material parameters. Then, the interactions between stress and diffusion before saturation is reached, are explored. Various effects are predicted on the classical sorption test, such as an evolution of the boundary condition with time, and a sorptiondesorption hysteresis.

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Ormenisan, Alina, Daniel Tamas Szava, Ioan Szava und Ciprian Dalai. „Mechanical Stress Exploration Inside of Dental Filling Materials by Means of Electronic Speckle Pattern Interferometry / Shearography“. Materiale Plastice 54, Nr. 4 (30.12.2017): 616–19. http://dx.doi.org/10.37358/mp.17.4.4911.

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Possible causes of microleakage and microfractures of dental fillings are often in the center of many academic research and investigations. Some authors found that one important cause of microleakage is the contraction/ shrinkage of the filling materials during polymerization. The purpose of this study is to demonstrate that microcracks and consequent microleakage is influenced by mechanical stresses occurring inside of dental filling materials and at the interface of the dental cavities and dental filling materials. We also tried to evaluate the deformation of some dental filling material types during mechanical loading. Cylindrical specimens were made of different types of dental filling materials, namely microhybrid composites and glass ionomer cement. Some extracted teeth were prepared with class II cavities, and filled. The lateral swelling of the tested specimens and the deformation of the filled teeth during vertical axial loading was measured with an optical method, ESPI/ Shearography.Of the tested specimen, the least deformable dental filling materials were the composite materials. During occlusal vertical loading of the filled teeth, there were found that mechanical stresses were different inside of the filling material than inside of the walls of the dental tissues, mechanical stressed being concentrated at the restoration interface. The ESPI/Shearography meth ode proved to be very useful for investigation in this field. Due to mechanical stresses accumulating at the interface of the dental filling material and the walls of the dental cavity, it is possible that later microcracks to appear due to masticatory forces.

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Omikrine-Metalssi, Othman, Badreddine Kchakech, Stéphane Lavaud und Bruno Godart. „Modelling the Swelling due to Delayed Ettringite Formation - Application to a Real Bridge“. Key Engineering Materials 711 (September 2016): 722–29. http://dx.doi.org/10.4028/www.scientific.net/kem.711.722.

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Delayed ettringite formation (DEF) can affect the long-term durability of concrete structures by causing cracking and expansion of the material. Consequently, mechanical properties decrease which may cause large structural disorders due to unexpected deformations and additional stresses in concrete and reinforcement. This reaction consists in ettringite crystallization within concrete after hardening is substantially complete, and in which no sulphates come from outside the cement paste. It may occur in materials that have been subjected to temperature above about 65 °C at early age and to high humidity. At this high temperature, the ettringite turns unstable while the concrete is still plastic and forms again after cooling in the hardened material, thus generating swelling due to crystallisation pressure.This article aims to present a new model for the calculation of structures affected by DEF and to study the effect of the prefabrication temperature on the development of this reaction. In this context, the elaborated model was applied to the 3D simulations of a real bridge affected by this phenomenon. The results highlight that the temperature reached in the precast beams of the studied bridge during prefabrication has a significant effect on the displacements and stresses. Therefore, more precise control of the prefabrication temperature has to be applied in order to prevent the swelling and damage to structures.

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Frieberg, Bradley R., Christopher M. Stafford, Joshua R. Graybill, Zachary C. Tronstad und Gery R. Stafford. „(Invited) Mechanical Response of Thin Nafion Films to Hydration“. ECS Meeting Abstracts MA2018-01, Nr. 32 (13.04.2018): 1987. http://dx.doi.org/10.1149/ma2018-01/32/1987.

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Ion-containing polymers, in particular Nafion, are a critical component in hydrogen fuel cells, where they are not only used as the proton conducting membrane but also as the ion conducting binder within the catalyst layer. Within the catalyst layer, Nafion is often confined to thicknesses on the order of ten nanometers or less. It is well reported that many physical properties of polymers deviate from their bulk like behavior when confined on length scales comparable to the size of the molecule, typically 10s of nanometers. The mechanical properties of the ionomer are of particular importance due to the swelling response to changes in hydration level. In this work, we have implemented a cantilever bending technique to investigate the swelling induced stresses in Nafion thin films as a function of humidity. We have found a significant influence of the film thickness on the swelling stresses as well as the Young’s modulus when the films are thinner than 50 nm; and the apparent increase in stiffness translates to a decrease in water content. Although the modulus of the film strongly depends on the processing and annealing conditions, the relative thickness dependence is independent of annealing. In addition to thermal annealing, hygrothermal aging and substrate interactions have also been observed to have a large influence on the thickness dependent mechanical behavior. The changes observed in the mechanical response are correlated to structural and chemical changes in the film shown by neutron and x-ray scattering as well as the IR absorption spectra.

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Loukidis, Dimitrios, Georgia Lazarou, Ploutarchos Tzampoglou und Thrasivoulos Stylianou. „Swelling and collapse behavior of expansive marl and its implications in foundation engineering“. E3S Web of Conferences 382 (2023): 01004. http://dx.doi.org/10.1051/e3sconf/202338201004.

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Expansive soils increase their volume upon wetting, but under high vertical stresses may exhibit collapse, with the latter aspect being rather overlooked in foundation engineering. Oedometer swelling/collapse tests on expansive Pliocene marls of various calcium carbonate content and plasticity index sampled from Nicosia, Cyprus, indicate that, unlike the free swelling strain, the swelling pressure is rather insensitive to the initial degree of saturation. Consequently, significant collapse strains upon wetting are not unlikely to occur in practical situations. The paper discusses the implications of this behavior in the case of shallow foundations and proposes methods of analysis. Under certain conditions, foundation design based on settlement calculations that use as input the fully saturated soil properties may be unconservative and supported structures may be exposed to severe risk of damage. For the design of mat foundations, stepwise distributions of the equivalent modulus of subgrade reaction across the mat as a function of the average bearing pressure are proposed based on the results of coupled finite element simulations. These distributions allow prediction of the peak bending moments produced at the end of the wet and dry seasons due to ground swelling and shrinkage, respectively, for the climatic conditions of Cyprus.

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Chowdhury, N., J. Wang, W. K. Chiu und W. Yan. „Residual Stresses Introduced to Composite Structures due to the Cure Regime: Effect of Environment Temperature and Moisture“. Journal of Composites 2016 (21.11.2016): 1–13. http://dx.doi.org/10.1155/2016/6468032.

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Material behaviour of structural components is very important to understand. In fibre reinforced polymer composite materials, this is more difficult in comparison to isotropic materials as they are made up of two constituents: the fibre and the matrix. For aerospace composite materials, the matrix is usually an epoxy resin that cures at a high temperature. This curing regime is known to introduce residual stresses to the composite material as it cools from the high cure temperature. However, how to consider these residual stresses in a structural analysis is still widely debated. In this paper, the authors investigated the offset of thermal residual strains introduced by the cure regime by the swelling of the composite when exposed to moisture.

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