Готові списки джерел за темами / Stress relaxation model

Добірка наукової літератури з теми "Stress relaxation model"

Автор: Grafiati

Опубліковано: 31 січня 2023

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Статті в журналах з теми "Stress relaxation model":

Guo, Jin Quan, Wu Zhou Meng, Fei Li, and Li Xin Wang. "Creep Prediction From Stress Relaxation Coupled With Equivalent Relaxation Rate." Applied Mechanics and Materials 644-650 (September 2014): 1382–85. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.1382.

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Several stress relaxation and creep tests of high temperature material are performed. According to the characteristics of stress relaxations and the superposition equation of diffusion and Maxwell equations of two stages, equivalent relaxation time and equivalent relaxation rate are proposed. Considering equivalent relaxation rate as the creep rate under constant stress, the relaxation-creep conversion model is built up and presented. Then the steady-state creep curve and creep rate are calculated. The results show that the numerical results are in good agreement with the experimental data. It indicates that equivalent relaxation rate can be employed for the analysis of steady-state creep rate. The conversion model and method can be used to design the creep strength and predict the life of the component at high temperature.

Raza, S. M., N. Farooqui, S. B. H. Abidi, S. A. Raza, and S. M. M. R. Naqvi. "Self-consistent stress relaxation model." Physica Status Solidi (a) 100, no. 2 (April 16, 1987): K149—K153. http://dx.doi.org/10.1002/pssa.2211000246.

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Duan, Xiaochang, Hongwei Yuan, Wei Tang, Jingjing He, and Xuefei Guan. "An Engineering Prediction Model for Stress Relaxation of Polymer Composites at Multiple Temperatures." Polymers 14, no. 3 (January 30, 2022): 568. http://dx.doi.org/10.3390/polym14030568.

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This study develops an engineering prediction model for stress relaxation of polymer composites, allowing the prediction of stress relaxation behaviour under a constant strain, over a range of temperatures. The model is based on the basic assumption that in the stress relaxation process the reversible strain is transformed to irreversible strain continuously. A strain-hardening model is proposed to incorporate nonlinear elastic behaviour, and a creep rate model is used to describe the irreversible deformation in the process. By using stress relaxation data at different temperatures, under different strains, the dependence on temperature and initial strain of the model parameters can be established. The effectiveness of the proposed model is verified and validated using three polymer composite materials. The performance of the model is compared with three commonly used stress relaxation models such as the parallel Maxwell and Prony series models. To ease the use of the proposed model in realistic structural problems, a user subroutine is developed, and the stress relaxation of a plate structure example is demonstrated.

Liu, Q., W. Chen, J. K. Guo, R. F. Li, D. Ke, Y. Wu, W. Tian, and X. Z. Li. "Fractional Stress Relaxation Model of Rock Freeze-Thaw Damage." Advances in Materials Science and Engineering 2021 (February 13, 2021): 1–8. http://dx.doi.org/10.1155/2021/3936968.

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Freeze-thaw cycle is a type of fatigue loading, and rock stress relaxation under freeze-thaw cycles takes into account the influence of the freeze-thaw cycle damage and deterioration. Rock stress relaxation under freeze-thaw cycles is one of the paramount issues in tunnel and slope stability research. To accurately describe the mechanical behaviour of stress relaxation of rocks under freeze-thaw, the software element is constructed based on the theory of fractional calculus to replace the ideal viscous element in the traditional element model. The freeze-thaw damage degradation of viscosity coefficient is considered. A new three-element model is established to better reflect the nonlinear stress relaxation behavior of rocks under freeze-thaw. The freeze-thaw and stress relaxation of rock are simulated by ABAQUS, the relevant model parameters are determined, and the stress relaxation equation of rock under freeze-thaw cycle is obtained based on numerical simulation results. The research shows that the test results are consistent with the calculated results, indicating that the constitutive equation can better describe the stress relaxation characteristics of rocks under freeze-thaw and provide theoretical basis for surrounding rock support in cold region.

Nonnenmacher, T. F., and W. G. Glöckle. "A fractional model for mechanical stress relaxation." Philosophical Magazine Letters 64, no. 2 (August 1991): 89–93. http://dx.doi.org/10.1080/09500839108214672.

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Guo, Jin Quan, Wei Zhang, and Xiao Hong Sun. "Stress Relaxation Continuum Damage Constitutive Equations for Relaxation Performance Prediction." Advanced Materials Research 455-456 (January 2012): 1434–37. http://dx.doi.org/10.4028/www.scientific.net/amr.455-456.1434.

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Stress relaxation constitutive equations based on Continuum Damage Mechanics, Kachanov-Robatnov creep model, and stress relaxation equation has been developed by analyzing stress relaxation damage mechanisms and considering the relationship that stress relaxation is creep at various stresses. And, the constitutive differential equations were integrated to predict stress relaxation performance by using numerical analysis technique. In order to validate the approach, the predicted results are compared to the experimental results of uni-axial isothermal stress relaxation tests conducted on 1Cr10NiMoW2VNbN steel with the same temperature of creep tests. Good agreement between results of relaxation tests and the predicted results indicates that the developed constitutive models can be used in the relaxation behavior evaluation of high temperature materials.

Liao, Chuanjun, Hongrong Fang, Hongrui Wang, and Man Man. "Study on characteristics and mathematical models of stress relaxation for metal O-rings." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 231, no. 7 (December 1, 2016): 826–37. http://dx.doi.org/10.1177/1350650116682152.

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The metal O-ring is effectively applied to extreme conditions and long-term uses for several decades, where conventional seals cannot meet the requirements. During the long-time service, the stress relaxation of the metal O-ring has been confirmed to be a potential damage to the sealing performance. By analyzing the sealing mechanism and the problem of the stress relaxation of the metal O-ring, a model has been developed to study its stress relaxation. The model includes the contact model, the stress–strain model, and the dynamic equation of stress relaxation. Based on the classical elastic-plastic model for two contact rough surfaces, the contact model of sealing zone is developed, by which the mechanical and geometric parameters of the sealing zone can be obtained for the initial state after the assembling. In the stress–strain model, the determination of stress and strain in the metal O-ring is performed by means of a simplified closed-form solution. The dynamic equation of stress relaxation using the stress-creep rate equation is developed, and is solved by combination of the contact model and the stress–strain model. The equation can be adopted for stress relaxation analysis of the metal O-ring at any time. After a validation of the model by comparison with experiments, a parametric study is presented. Simulation results corresponding with the mathematical models explain how the stress relaxation characteristic of the metal O-ring is influenced by a number of parameters.

LI, W. H., G. CHEN, S. H. YEO, and H. DU. "STRESS RELAXATION OF MAGNETORHEOLOGICAL FLUIDS." International Journal of Modern Physics B 16, no. 17n18 (July 20, 2002): 2655–61. http://dx.doi.org/10.1142/s0217979202012803.

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In this paper, the experimental and modeling study and analysis of the stress relaxation characteristics of magnetorheological (MR) fluids under step shear are presented. The experiments are carried out using a rheometer with parallel-plate geometry. The applied strain varies from 0.01% to 100%, covering both the pre-yield and post-yield regimes. The effects of step strain, field strength, and temperature on the stress modulus are addressed. For small step strain ranges, the stress relaxation modulus G(t,γ) is independent of step strain, where MR fluids behave as linear viscoelastic solids. For large step strain ranges, the stress relaxation modulus decreases gradually with increasing step strain. Morever, the stress relaxation modulus G(t,γ) was found to obey time-strain factorability. That is, G(t,γ) can be represented as the product of a linear stress relaxation G(t) and a strain-dependent damping function h(γ). The linear stress relaxation modulus is represented as a three-parameter solid viscoelastic model, and the damping function h(γ) has a sigmoidal form with two parameters. The comparison between the experimental results and the model-predicted values indicates that this model can accurately describe the relaxation behavior of MR fluids under step strains.

Szot, Wiktor. "Stress relaxation in samples made of acrylonitrile butadiene styrene material manufactured by fused deposition modelling." Mechanik 94, no. 12 (December 8, 2021): 46–50. http://dx.doi.org/10.17814/mechanik.2021.12.16.

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Increased interest in fused deposition modeling (FDM) resulting, for example, from its use in the production of utility models determines the undertaking of research on mechanical and rheological properties of materials. Mechanical and rheological properties of models made of materials used in FDM technology depend on technological parameters. In this paper, the effect of 0° and 90° print orientation on stress relaxation was analyzed. Additionally, the usefulness of the rheological model to describe the relaxation curve was evaluated. Stress relaxation tests were performed by tensile testing. The five-parameter Maxwell-Wiechert model was used to describe stress relaxation. The tests showed little effect of print orientation on the rheological parameters of the five-parameter model. The Maxwell-Wiechert model showed a very good approximation to the stress relaxation curves.

Guo, Jin Quan, Li Xin Wang, and Fu Zhen Xuan. "Creep Based Prediction Model of Stress Relaxation Behavior for High Temperature Materials." Advanced Materials Research 139-141 (October 2010): 356–59. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.356.

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An average creep rate conversion model based on Schlottner-Seeley creep assessment procedure and creep damage equation has been developed by considering the relationship that two stages of stress relaxation are corresponding to the first and the second creep stage respectively and the effect of these two kinds of creep rate on relaxation, and stress relaxation is creep at various stresses. And an incremental calculation prediction methodology of stress relaxation performance was established. The predicted results are compared with the data of stress relaxation tests conducted on bolting steel 1Cr10NiMoW2VNbN used in ultra-supercritical turbines. Validation results indicate that the developed model has led to better consistent results with the measured data and thus can be recommended in stress relaxation behavior prediction of high temperature materials.

Більше джерел

Дисертації з теми "Stress relaxation model":

Griebel, Matthew Alexander. "Viscoelastic Anisotropic Finite Element Mixture Model of Articular Cartilage using Viscoelastic Collagen Fibers and Validation with Stress Relaxation Data." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/743.

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Experimental results show that collagen ﬁbers exhibit stress relaxation under tension and a highly anisotropic distribution. To further develop the earlier model of Stender [1], the collagen constituent was updated to reﬂect its intrinsic viscoelasticity and anisotropic distribution, and integrated with an existing mixture model with glycosaminoglycans and ground substance matrix. A two-term Prony series expansion of the quasi-linear viscoelastic model was chosen to model the viscoelastic properties of the collagen ﬁbers. Material parameters were determined by using the simplex method to minimize the sum of squared errors between model results and experimental stress relaxation data of tissue in tension. Collagen elastic ﬁber modulus was calculated by ﬁtting to the equilibrium data and viscoelastic parameters were determined by ﬁtting to the relaxation curve. Results of newborn (~1-3 week old) untreated bovine articular cartilage explants from the patellar femoral groove as well as explants cultured in transforming growth factor-β1 (TGF-β1), from both the superﬁcial (~0-0.5 mm from the articular surface) and middle (~0.5-1.0 mm from the articular surface) layers were compared to examine the effects of TGF- β1. TGF-β1 has been shown to maintain or even enhance mechanical properties of articular cartilage in compression and tension [2, 3] and this study continues with the hope that it may be used to improve tissue engineering of mature cartilage to better survive implantation in vivo for the successful repair of articular cartilage defects. Results show that TGF-β1 has a maturational effect on collagen, causing the tissue to become stiffer through an increase in elastic collagen ﬁber modulus and less viscous through shorter relaxation time and less stress relaxation (tissue retained a higher percentage of residual stress). The results of this study further advance the understanding of the effects of location and treatment with TGF-β1.

Davis, Frances Maria. "Nonlinear Viscoelastic Behavior of Ligaments and Tendons: Models and Experiments." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/50939.

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Ligaments and tendons are rope-like structures in our body that possess time- and history- dependent material properties. Despite the many advances made in experimental and theoretical biomechanics, the material properties of these biological structures are still not fully characterized. This dissertation represents a step forward in the development of combined theoretical and experimental tools that capture the time- and history-dependent material properties of ligaments and tendons.

The mechanical behavior of bundles of collagen fibers which form ligaments and tendons was investigated. Axial stress-stretch data and stress relaxation data at different axial stretches were collected by testing rat tail tendon fascicles. The experimental results demonstrated, for the first time, that the shape of the normalized axial stress relaxation curve depends on the axial stretch level thus suggesting that the fascicles are nonlinear viscoelastic. A constitutive model was then formulated within the nonlinear integral representation frame- work proposed by Pipkin and Rogers (1968). Unlike the well-known quasi-linear viscoelastic model, the proposed constitutive law was able to capture the observed nonlinearities in the stress relaxation response of rat tail tendon fascicles.

By extending the constitutive model for collagen fiber bundles, a new nonlinear three- dimensional model for the stress relaxation of skeletal ligaments was formulated. The model accounts for the contribution of the collagen fibers and the group substance in which they are embedded. Published uniaxial experimental data on the stress relaxation of human medial collateral ligaments were used to determine the model parameters. The model predictions for simple shear in the fiber direction, simple shear transverse to the fiber direction, and equibiaxial extension were then examined and, for the case of simple shear in the fiber direction, such predictions were found to be in good agreement with published experimental data.

The relationship between the mechanical response and structure of suspensory ligaments was examined by performing state-of-the-art small angle x-ray diffraction experiments in tandem with incremental stress relaxation tests. Specifically, small angle x-ray diffraction was used to measure changes in strain and orientation of collagen fibrils during the stress relaxation tests. Throughout the tests the collagen fibrils were found to gradually orient towards the loading direction. However, the collagen fibril strain did not change significantly suggesting that collagen fibers do not play a significant role in dissipating load during stress relaxation.
Ph. D.

Duffrene, Lucas. "Comportement viscoélastique d'un verre silico-sodocalcique dans le domaine des températures intermédiaires : approche phénoménologique et modélisation en triaxialité." Paris, ENMP, 1994. http://www.theses.fr/1994ENMP0515.

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Les opérations de mise en forme ou de traitement thermique (trempe, recuisson) sont généralement effectuées à des températures intermédiaires (500-650c) et à des niveaux de contraintes modérés pour lesquels le comportement mécanique du verre peut être décrit par une loi viscoélastique linéaire. L'objectif de la thèse est de réaliser une démarche expérimentale complète afin de modéliser le comportement viscoélastique en triaxialité d'un verre silico-sodocalcique. Les modules d'élasticité du verre ont été mesures par diffusion Brillouin dans le domaine de la transition. Des essais statiques de relaxation des contraintes et de fluage-recouvrance en cisaillement et en sollicitation uniaxiale ont été réalisés autour de la transition vitreuse. Ils permettent en particulier de montrer la dualité fluage-relaxation. Des essais dynamiques en cisaillement ont été également réalisés afin de montrer la correspondance statique-dynamique. Un développement de la théorie de la viscoélasticite par l'introduction des moments des spectres de relaxation et de retard ainsi que des constantes viscoélastiques permet d'obtenir des relations fondamentales entre les sollicitations uniaxiale, de cisaillement et de pression hydrostatique. Ainsi, dans le cadre du modèle de Maxwell généralisé, la partie hydrostatique du comportement viscoélastique est déterminée à partir des essais en sollicitation uniaxiale et par la connaisance du comportement en cisaillement. On montre également que la fonction de Kohlraush et le modèle de Perez ne conviennent pas pour décrire d'une manière phénomenologique le comportement viscoélastique du verre silico-sodocalcique. Le modèle de Maxwell généralisé est validé en comparant les résultats d'un calcul de structure avec un essai présentant un état de contraintes triaxiales complexes. Le modèle viscoélastique déterminé peut être étendu à la thermoviscoélasticite pour simuler les procédés de formage, de trempe des vitrages automobiles en verre silico-sodocalcique

Mathiesen, Danielle Samone. "Experiments, Constitutive Modeling, and Multi-Scale Simulations of Large Strain Thermomechanical Behavior of Poly(methyl methacrylate) (PMMA)." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1415694651.

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Nguyen, Trung Dung. "Experimental and numerical investigation of strain-rate dependent mechanical properties of single living cells." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/82791/1/Trung%20Dung_Nguyen_Thesis.pdf.

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The objective of this project is to investigate the strain-rate dependent mechanical behaviour of single living cells using both experimental and numerical techniques. The results revealed that living cells behave as porohyperlastic materials and that both solid and fluid phases within the cells play important roles in their mechanical responses. The research reported in this thesis provides a better understanding of the mechanisms underlying the cellular responses to external mechanical loadings and of the process of mechanical signal transduction in living cells. It would help us to enhance knowledge of and insight into the role of mechanical forces in supporting tissue regeneration or degeneration.

Valeš, Jan. "Počítačová simulace kolapsu budovy zplastizováním kloubů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225731.

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The aim of the thesis is to create an analytical 2D model of a multi-storey building and its consequent loading until the point of collapse which occures due to formation of plastic hinges. The first part is going to present a linear analysis of the problem; it focuses on location and level of load when the plastic hinges are formed. Then a nonlinaer analysis is going to be performed by RFEM programme using postcritical analysis and dynamic relaxation. Differences between the results of mentioned types and methods of analysis are going to be compared and an impact of variables is going to be evaluated .

Nain, Vaibhav. "Efficient thermomechanical modeling of large parts fabricated by Directed Energy Deposition Additive Manufacturing processes." Thesis, Lorient, 2022. http://www.theses.fr/2022LORIS630.

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Les procédés de fabrication additive laser par dépôt de poudre offrent une opportunité unique pour la fabrication de grandes pièces à géométrie complexe. Cependant, les déformations mécaniques induites par ces procédés entrainent des défauts pouvant conduire à des pièces rebutées. Au cours de cette thèse, différents modèles ont donc été développés pour mieux comprendre l’apparition de ces déformations en fonction des paramètres opératoires. Un premier modèle thermomécanique prédit le comportement élastoplastique lors de la construction d’un mur en acier inoxydable 316L. L’apport de chaleur est modélisé par une source double ellipsoïdale mobile et la construction des couches se fait à l’aide d’une méthode hybride « Quiet/Active élément ». Un écrouissage isotrope non linéaire est considéré, avec prise en compte de la restauration d’écrouissage à hautes températures. Afin de réduire drastiquement les temps de calcul, une nouvelle source de chaleur est proposée utilisant une source ellipsoïdale allongée qui moyenne l’énergie sur un intervalle d’espace et de temps. Cependant, un intervalle d’espace trop grand diminue la précision du modèle. De nouveaux paramètres sont alors introduits afin d’identifier le meilleur compromis entre temps de calcul et précision. L’ensemble des modèles proposés est confronté avec succès avec des données expérimentales en termes de température et déplacement et ce pour différents paramètres opératoires. Enfin, des modèles multi-échelles basés l’activation par couche ou les méthodes de déformations inhérentes sont étudiés en vue de réduire les temps de calcul
Directed Energy Deposition (DED) Additive Manufacturing technology offers a unique possibility of fabricating large-scale complex-shape parts. However, process-induced deformation in the fabricated part is still a big obstacle in successfully fabricating large-scale parts. Therefore, multiple numerical models have been developed to understand the accumulation of induced deformation in the fabricated part. The first model predicts the thermo-elastoplastic behaviour that captures the laser movement. The laser-material interaction and metal deposition are modeled by employing a double ellipsoid heat source and the Quiet/Active material activation method respectively. The model considers isotropic non-linear material hardening to represent actual metal behaviour. It also employs an instantaneous stress relaxation model to simulate the effects of physical phenomena like annealing, solid-state phase transformation, and melting. Using this model as a reference case, an efficient model is developed with an objective to reduce the computation time and make it feasible to simulate large-part. The model employs an Elongated Ellipsoid heat source that averages the heat source over the laser path which reduces the computational burden drastically. However, averaging over large laser path results in inaccurate results. Therefore, new parameters are developed that identify the best compromise between computation time reduction and accuracy. Both models are validated with experimental data obtained from several experiments with different process parameters. Finally, other Multi- scale methods such as the Layer-by-layer method and Inherent Strain-based methods are implemented and explored

Fitzgerald, Martha Moore. "Development and 3D Printing of Interpenetrating Network Hydrogel Materials for use as Tissue-Mimetic Models." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1430488189.

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Widmann, Frédéric. "Epitaxie par jets moléculaires de GaN, AlN, InN et leurs alliages : physique de la croissance et réalisation de nanostructures." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10234.

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Ce travail a porte sur la croissance epitaxiale des nitrures d'elements iii gan, aln, et inn, en utilisant l'epitaxie par jets moleculaires assistee par plasma d'azote. Nous avons optimise les premiers stades de la croissance de gan ou aln sur substrat al#2o#3 (0001). Le processus utilise consiste a nitrurer la surface du substrat a l'aide du plasma d'azote, afin de la transformer en aln, puis a faire croitre une couche tampon d'aln ou de gan a basse temperature, avant de reprendre la croissance de gan ou aln a haute temperature (680 a 750c). Nous avons en particulier etudie les proprietes d'une couche de gan en fonction de la temperature a laquelle est realisee l'etape de nitruration. Lorsque les conditions de demarrage de la croissance sont optimisees, nous avons pu observer des oscillations de rheed pendant la croissance de la couche de gan. Nous avons etudie l'effet du rapport v/iii sur la morphologie de surface et les proprietes optiques et structurales de cette couche. Nous avons propose l'utilisation de l'indium en tant que surfactant pour ameliorer ces proprietes. Nous avons ensuite aborde la realisation de superreseaux gan/aln dont nous avons optimise les interfaces. Les mecanismes de relaxation des contraintes de aln sur gan et gan sur aln ont ete etudies. Nous avons egalement elabore les alliages algan et ingan, comme barrieres quantiques dans les heterostructures. Nous avons montre que la relaxation elastique des contraintes de gan en epitaxie sur aln donne lieu a la formation d'ilots de tailles nanometriques, qui se comportent comme des boites quantiques. Leur densite et leur taille dependent de la temperature de croissance, et des conditions de murissement apres croissance. Les proprietes optiques de ces ilots sont gouvernees a la fois par les effets de confinement quantique et par le fort champ piezo-electrique induit par la contrainte dans les ilots.

Sweeney, John, Philip D. Caton-Rose, Paul E. Spencer, H. Pua, C. P. J. O'Connor, P. J. Martin, and G. Menary. "The large strain response of polypropylene in multiaxial stretching and stress relaxation." 2013. http://hdl.handle.net/10454/9738.

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Книги з теми "Stress relaxation model":

Bernier, Diane. Stress reduction: A model, an evaluation : summary of research. [Montréal]: School of Social Work, Université de Montréal, 1988.

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Neely, Braxtel L. Two-dimensional relaxation method flow model (RMFM) for hydraulic structures. Little Rock, Ark: U.S. Dept. of the Interior, U.S. Geological Survey, 1992.

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Neely, Braxtel L. Two-dimensional relaxation method flow model (RMFM) for hydraulic structures. Little Rock, Ark: U.S. Dept. of the Interior, U.S. Geological Survey, 1992.

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Neely, Braxtel L. Two-dimensional relaxation method flow model (RMFM) for hydraulic structures. Little Rock, Ark: U.S. Dept. of the Interior, U.S. Geological Survey, 1992.

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Neely, Braxtel L. Two-dimensional relaxation method flow model (RMFM) for hydraulic structures. Little Rock, Ark: U.S. Dept. of the Interior, U.S. Geological Survey, 1992.

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Rubinstein, Robert. Relaxation approximation in the theory of shear turbulence. Hampton, VA: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1995.

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Rubinstein, Robert. Relaxation approximation in the theory of shear turbulence. Hampton, VA: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1995.

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Kudinov, Igor', Anton Eremin, Konstantin Trubicyn, Vitaliy Zhukov, and Vasiliy Tkachev. Vibrations of solids, liquids and gases taking into account local disequilibrium. ru: INFRA-M Academic Publishing LLC., 2022. http://dx.doi.org/10.12737/1859642.

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The monograph presents the results of the development and research of new mathematical models of the processes of vibrations of solids, liquids and gases, taking into account local disequilibrium. To derive differential equations, the Navier—Stokes equations, Newton's second law and modified formulas of the classical empirical laws of Fourier, Hooke, Newton are used, which take into account the velocities and accelerations of the driving forces (gradients of the corresponding quantities) and their consequences (heat flow, normal and tangential stresses). The conditions for the occurrence of shock waves of stresses and displacements in dynamic thermoelasticity problems formulated taking into account relaxation phenomena in thermal and thermoelastic problems are investigated, new results are obtained in the study of longitudinal and transverse vibrations of rods, strings, liquids and gases, and the conditions for the excitation of gas self-oscillations arising from a time-constant heat source are determined. It is intended for scientific and technical workers specializing in mathematics, thermophysics, thermoelasticity, as well as teachers and students of technical universities.

Morgan, Ruby. Adult Coloring Book of 30 Funny Quotes for Model Railroads Lovers: 30 Funny Sayings and Beautiful Mandala Patterns to Color, Art Therapy Activity Book for Anxiety and Stress Relief, Mindful Meditation and Relaxation. Independently Published, 2020.

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Morgan, Ruby. Adult Coloring Book of 30 Funny Quotes for Model Cars Lovers: 30 Funny Sayings and Beautiful Mandala Patterns to Color, Art Therapy Activity Book for Anxiety and Stress Relief, Mindful Meditation and Relaxation. Independently Published, 2020.

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Частини книг з теми "Stress relaxation model":

Mao, Wei Min, W. Mao, and Yong Ning Yu. "Reaction Stress Model and Relaxation of Reaction Stress among the Grains during Tensile Deformation of fcc Metals." In Materials Science Forum, 995–1000. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-975-x.995.

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Tohill, R., M. R. Hien, N. McGuinness, L. Chung, and R. L. Reuben. "Short-term stress relaxation of porcine periodontal ligament - finding an appropriate visco-elastic model." In IFMBE Proceedings, 335–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03891-4_89.

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Wu, Hao, and Zheng Zhong. "A Novel Nonlinear Kinematic Hardening Model for Uniaxial/Multiaxial Ratcheting and Mean Stress Relaxation." In Fatigue and Fracture Test Planning, Test Data Acquisitions and Analysis, 227–45. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2017. http://dx.doi.org/10.1520/stp159820160059.

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Burba, M. E., D. J. Buchanan, M. J. Caton, R. John, and R. A. Brockman. "Microstructure-Sensitive Model for Predicting Surface Residual Stress Relaxation and Redistribution in a P/M Nickel-Base Superalloy." In Superalloys 2016, 619–27. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119075646.ch66.

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van Duyl, W. A., A. T. M. van der Zon, C. W. J. Oomens, and A. C. Drogendijk. "Stress Relaxation, Used as a Tool for Diagnosis of Incompetence of Human Cervix in Terms of a Mixture Model of Tissue." In Biomechanics: Basic and Applied Research, 193–98. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3355-2_22.

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Garrett, Steven L. "Elasticity of Solids." In Understanding Acoustics, 179–233. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-44787-8_4.

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Abstract If a solid is initially at rest and equal and opposing forces are applied to that object, Newton’s Second Law guarantees that the object will remain at rest because the net force on the sample is zero. If that object is an elastic solid, then those forces will cause the solid to deform by an amount that is directly proportional to those applied forces. When the forces are removed, the sample will return to its original shape and size. That reversibility is the characteristic that is required if we say the behavior of the solid is “elastic.” This chapter will quantify the elastic behavior of solids by introducing the concepts of stress and strain and expressing their linear relationship through the definition of elastic moduli that depend only upon the material and the nature of the deformation and not upon the shape of the object. Those concepts allow us to generalize Hooke’s law. As before, the combination of a linear equation of state with Newton’s Second Law will now describe wave motion in solids. The introduction of a relaxation time, through the Maxwell model, will let these results be generalized to viscoelastic materials and then be applied to rubber vibration isolators.

Nam, T. H., I. Petríková, and B. Marvalová. "Experimental and numerical investigation of compression stress relaxation of isotropic magneto-sensitive elastomeric composite." In Constitutive Models for Rubber XII, 153–58. London: CRC Press, 2022. http://dx.doi.org/10.1201/9781003310266-25.

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Hong, Zhang Lian, Hidehiro Yoshida, and Taketo Sakuma. "High Temperature Creep Strength of Si₃N₄-Y₂Si₂O₇ Ceramics by Stress Relaxation Based on a New Interpretation Model." In Key Engineering Materials, 1420–23. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-410-3.1420.

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Belyamani, Imane, and Jérémy Grondin. "Creep, Stress Relaxation, and Yielding Mechanisms." In Characterization and Failure Analysis of Plastics, 1–14. ASM International, 2022. http://dx.doi.org/10.31399/asm.hb.v11b.a0006934.

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Abstract This article describes the general aspects of creep, stress relaxation, and yielding for homogeneous polymers. It then presents creep failure mechanisms in polymers. The article discusses extrapolative methods for the prediction of long-term creep failure in polymer materials. Then, the widely used models to simulate the service life of polymers are highlighted. These include the Burgers power-law model, the Findley power-law model, the time-temperature superposition (or equivalence) principle (TTSP), and the time-stress superposition principle (TSSP). Additionally, the Larson-Miller parametric method, one of the most common to describe the material deformation and rupture time, is also discussed.

Anand, Lallit, Ken Kamrin, and Sanjay Govindjee. "Linear viscoelasticity." In Introduction to Mechanics of Solid Materials, 307–39. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780192866073.003.0019.

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Abstract This chapter introduces the essential elements of linear viscoelastic material behaviour and modelling in a one-dimensional setting. Stress-relaxation and creep phenomena are discussed and modelled using Boltzmann’s superposition principle, leading to stress-relaxation integral and creep integral forms of the stress-strain relations. A rheological model known as the standard linear solid is introduced, and the resulting kernel functions for stress-relaxation and creep are discussed. The correspondence principle between linear viscoelasticity and linear elasticity is introduced and used to connect relaxation and creep formulations. This principle is also used to discuss the solution of structural problems involving the bending of beams and torsion of shafts made from linear viscoelastic materials. A rheological model known as the generalized Maxwell model together with the attendant Prony series form of the stress-relaxation function are presented, and a time-integration procedure for the resulting constitutive equation for linear viscoelasticity using the Herrmann–Peterson recursion relation is derived.

Тези доповідей конференцій з теми "Stress relaxation model":

Riva, Andrea, and Maurizio Maldini. "Stress Relaxation Modelling." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43755.

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Modern gas turbine bolts experience severe operational conditions due to high temperatures and elevated axial stresses, generated by the tightening couple applied during the turbine assembly. In such conditions the relaxation of the initial stress due to viscous phenomena has to be taken into account in order to guarantee the proper operation of the turbine. Relaxation modelling can either be based on strain controlled relaxation tests or load controlled creep tests. Both solutions present difficulties: relaxation tests entail critical experimental issues, whereas creep tests may not be significant for the given strain controlled operational condition of a gas turbine bolt. Some of these problems will be described in the paper and solutions will be provided. The performances of several models for stress relaxation quantification will be compared, highlighting advantages and disadvantages of each approach. In particular, great emphasis will be given to those aspects which are relevant for bolt design or tightening load calculation. For instance, some important requirements are: firstly, the possibility to implement the given model easily in finite element calculations; secondly, the possibility to accurately calculate the relaxation in the second life of a serviced bolt after re-tightening; lastly, the possibility to reduce as much as possible the time required for the experimental tests. In order to evaluate the coefficients of the different models considered in the study, creep tests were performed at 450°C and 475°C with applied stresses producing a strain ε = 1% in a time range of 1000–10000h and stress relaxation tests were performed at the same temperatures with initial strain in the range of 0.2%. After some stress relaxation, the specimens were reloaded at the initial stress several times in order to simulate the aforesaid service conditions of bolts. In the paper it will be shown how a valid model, capable of predicting the stress relaxation with acceptable accuracy, can be fed either by creep or relaxation tests, provided that the experimental tests and the related data elaboration are conducted with the proper methodology. This scenario provides the engineer responsible for material model creation with a remarkable flexibility, essential to fulfill the requirements of modern GT design, in terms of accuracy, promptness of data collection and possibility of FEM implementation.

Zhou, Yu, Xuedong Chen, Zhichao Fan, and Yichun Han. "A Physically Based Damage Constitutive Model for Stress Relaxation." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28679.

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A damage constitutive model for stress relaxation was proposed based on the continuum damage mechanics theory, in terms of the characteristics of damage induced by stress relaxation which is associated with reheat cracking. The effects of strain hardening and the precipitation and growth of carbides on the stress evolution behavior were considered in the present model. To validate the accuracy of the constitutive model, comparison of the predicted result provided by the model and the experimental data of stress relaxation for 2.25Cr-1Mo-0.25V ferritic steel was made. It is shown that the damage constitutive model can be used to predict the stress relaxation behavior and reheat cracking further for low alloy ferritic steels.

"Residual Stress Relaxation in Welded Steel Joints – an Experimentally-based Model." In Residual Stresses 10. Materials Research Forum LLC, 2016. http://dx.doi.org/10.21741/9781945291173-52.

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Eid, M., H. Al Osman, and A. El Saddik. "A mathematical model for personalized relaxation for stress management." In 2013 IEEE International Symposium on Medical Measurements and Applications (MeMeA). IEEE, 2013. http://dx.doi.org/10.1109/memea.2013.6549736.

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Hongbo, Wang, Wang Chunguang, and Guo Yueying. "Establishment of the Pasturage Stress Relaxation Model Based on ADAMS." In 2009 WRI World Congress on Software Engineering. IEEE, 2009. http://dx.doi.org/10.1109/wcse.2009.290.

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Ellingham, Richard, and Tim Giffney. "Stress and Resistance Relaxation for Carbon Nanoparticle Silicone Rubber Composite Large-Strain Sensors." In ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-69206.

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Abstract The high stretchability, scalability and bio-compatibility of carbon black nanoparticle (CB)-polydimethylsiloxane (PDMS) elastomer composites are attractive characteristics for diverse applications ranging from the biomedical to aerospace fields. These materials are particularly useful as high strain sensors, but show stress relaxation and resistance relaxation behaviour that must be better understood in order to improve sensing performance and optimize the material design. In this work, we have characterized and modelled the resistance relaxation behaviour of these composites to understand the response of resistance to transient step strain input. CB-PDMS specimens have been fabricated with 7.5 and 10 weight percentage (w.t.%) of CB and subjected to repeated stretching while continually monitoring resistance and stress. A model for the resistive relaxation in time has been developed using 30 relaxations to give maximum coefficients of variance of the constants of 18.54% and 52.72% for 7.5 and 10 w.t.% of CB. The ability to model resistance relaxation is useful for the development of, accurate, highly flexible dynamic strain sensors.

Barua, Bipul, and Mrinal C. Saha. "Tensile Stress Relaxation of Thermosetting Polyurethane Solid and Foam." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-39419.

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Stress relaxation behavior of thermosetting polyurethane (PU) solid and foam were investigated in tensile mode using a dynamic mechanical analyzer (DMA). PU solid samples were manufactured in a closed mold under compression to avoid any foam formation, whilst the foam samples were manufactured inside a woven using a silicone mold. Effects of cure and the post-cure temperature were also investigated on the stress relaxation behavior. Samples in the form of rectangular cross-section were subjected to a predetermined amount tensile strain and the tensile force was recorded as a function of time. Relaxation modulus was determined for different temperatures up to near the glass transition temperature. It was found that the viscous part becomes dominant with increasing test temperature. The experimental data was precisely modeled using a generalized Maxwell’s model and the characteristic relaxation time was identified with the corresponding relaxation process. Although the stress relaxation behavior of PU solid and PU foams were found similar at room temperature, the relaxation behavior of the foam was found to be influenced by the cell morphology at higher temperature.

Zhang, Jinmiao, Pingsha Dong, and Shaopin Song. "Stress Relaxation Behavior in PWHT of Welded Components." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57826.

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This paper is focused on the discussion of weld residual stress relaxation in a uniform post weld heat treatment (PWHT). In particular, the paper is attempted to address a fundamental issue related to the PWHT stress relaxation behavior, i.e., what is the dominant stress relaxation mechanism in PWHT? Is it due to creep or material strength reduction at elevated temperature? The paper starts with a simplified 3-bar weld model to demonstrate how weld residual stress is developed and relaxed. It then follows with an example of thick section narrow groove weld to highlight the results and conclusions. The results clearly indicate that creep mechanism plays a dominant role in the stress relaxation of PWHT. Several other important observations related to the stress relaxation are also summarized.

Kostenko, Y., and K. Naumenko. "Prediction of Stress Relaxation in Power Plant Components Based on a Constitutive Model." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63608.

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Many power plant components and joint connections are subjected to complex thermo-mechanical loading paths under severe temperature environments over a long period. An important part in the lifetime assessment is the reliable prediction of stress relaxation using improved creep modeling to avoid possible integrity or functionality issues and malfunction in such components. The aim of this work is to analyze the proposed constitutive model for advanced high chromium steels with the goal of predicting stress relaxation over the long term. The evolution equations of the constitutive model for inelastic material behavior are introduced to account for hardening and softening phenomena. The material properties were identified for 9–12%CrMoV steels in the creep range. The model is applied to the stress relaxation analysis of power plant components. The results for long-term assessment, which are encouragingly close to reality, will be presented and discussed. An outlook on further developments of the model and assessment procedure is also provided.

Churchfield, Matthew, and Gregory Blaisdell. "A Reynolds Stress Relaxation Turbulence Model Applied to A Wingtip Vortex Flow." In 49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2011. http://dx.doi.org/10.2514/6.2011-663.

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Звіти організацій з теми "Stress relaxation model":

Scheufele, Peter M. The Effects of Progressive Relaxation and Music on Attention, Relaxation and Stress Responses: An Investigation of the Cognitive-Behavioral Model of Relaxation. Fort Belvoir, VA: Defense Technical Information Center, January 1999. http://dx.doi.org/10.21236/ad1012237.

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Ramakrishnan, Aravind, Ashraf Alrajhi, Egemen Okte, Hasan Ozer, and Imad Al-Qadi. Truck-Platooning Impacts on Flexible Pavements: Experimental and Mechanistic Approaches. Illinois Center for Transportation, November 2021. http://dx.doi.org/10.36501/0197-9191/21-038.

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Truck platoons are expected to improve safety and reduce fuel consumption. However, their use is projected to accelerate pavement damage due to channelized-load application (lack of wander) and potentially reduced duration between truck-loading applications (reduced rest period). The effect of wander on pavement damage is well documented, while relatively few studies are available on the effect of rest period on pavement permanent deformation. Therefore, the main objective of this study was to quantify the impact of rest period theoretically, using a numerical method, and experimentally, using laboratory testing. A 3-D finite-element (FE) pavement model was developed and run to quantify the effect of rest period. Strain recovery and accumulation were predicted by fitting Gaussian mixture models to the strain values computed from the FE model. The effect of rest period was found to be insignificant for truck spacing greater than 10 ft. An experimental program was conducted, and several asphalt concrete (AC) mixes were considered at various stress levels, temperatures, and rest periods. Test results showed that AC deformation increased with rest period, irrespective of AC-mix type, stress level, and/or temperature. This observation was attributed to a well-documented hardening–relaxation mechanism, which occurs during AC plastic deformation. Hence, experimental and FE-model results are conflicting due to modeling AC as a viscoelastic and the difference in the loading mechanism. A shift model was developed by extending the time–temperature superposition concept to incorporate rest period, using the experimental data. The shift factors were used to compute the equivalent number of cycles for various platoon scenarios (truck spacings or rest period). The shift model was implemented in AASHTOware pavement mechanic–empirical design (PMED) guidelines for the calculation of rutting using equivalent number of cycles.