Auswahl der wissenschaftlichen Literatur zum Thema „Instantaneous strain“
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Zeitschriftenartikel zum Thema "Instantaneous strain"
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Gao, Li Lan, Xu Chen und Hong Gao. „Creep-Recovery Behaviors of Anisotropic Conductive Adhesive Film with Temperature and Hygrothermal Aging“. Advanced Materials Research 509 (April 2012): 16–21. http://dx.doi.org/10.4028/www.scientific.net/amr.509.16.
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The effects of temperature, stress level and hygrothermal aging on the creep-recovery behaviors of anisotropic conductive adhesive film (ACF) were investigated experimentally using a dynamic mechanical analyzer (DMA). It is found that the initial strains, instantaneous strains, and creep or recovery rates increase with increasing temperature，however decrease with increasing hygrothermal aging time. The change of creep or recovery rates at low temperature is apparent, however the creep or recovery rates increase obviously at temperatures above 25 oC with increasing stress level. For the hygrothermal aged ACF, the time to reach steady creep stage or steady recovery stage is reduced significantly compared with the unaged sample. The strain jumps at instantaneous loading decrease visibly and the strain jumps at instantaneous unloading decrease slightly with increasing aging time. And the strain jumps at instantaneous loading and unloading increase with increasing stress level for the unaged and aged ACFs.
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Diab, Mazen, Teng Zhang, Ruike Zhao, Huajian Gao und Kyung-Suk Kim. „Ruga mechanics of creasing: from instantaneous to setback creases“. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 469, Nr. 2157 (08.09.2013): 20120753. http://dx.doi.org/10.1098/rspa.2012.0753.
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We present mechanics of surface creasing caused by lateral compression of a nonlinear neo-Hookean solid surface, with its elastic stiffness decaying exponentially with depth. Nonlinear bifurcation stability analysis reveals that neo-Hookean solid surfaces can develop instantaneous surface creasing under compressive strains greater than 0.272 but less than 0.456. It is found that instantaneous creasing is set off when the compressive strain is large enough, and the longest-admissible perturbation wavelength relative to the decay length of the elastic modulus is shorter than a critical value. A compressive strain smaller than 0.272 can only trigger bifurcation of a stable wrinkle that can prompt a setback crease upon further compression. The minimum compressive strain required to develop setback creasing is found to be 0.174. If the relative longest-admissible perturbation wavelength is long enough, then the wrinkle can fold before it creases, and the specimen can be compressed further beyond the Biot critical strain limit of 0.456. Various bifurcation branches on a plane of normalized longest-admissible wavelength versus compressive strain delineate different phases of corrugated surface configurations to form a ruga phase diagram. The phase diagram will be useful for understating surface crease, as well as for controlling ruga structures for various applications, such as designing stretchable electronics.
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Dvorak, G. J. „Thermal Expansion of Elastic-Plastic Composite Materials“. Journal of Applied Mechanics 53, Nr. 4 (01.12.1986): 737–43. http://dx.doi.org/10.1115/1.3171852.
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Exact relationships are derived between instantaneous overall thermal stress or strain vectors and instantaneous overall mechanical stiffness or compliance, for two binary composite systems in which one of the phases may deform plastically. Also, the local instantaneous thermal strain and stress concentration factors are related in an exact way to the corresponding mechanical concentration factors. The results depend on instantaneous thermoelastic constants and volume fractions of the phases. They are found for fibrous composites with two distinct elastically isotropic or transversely isotropic phases, and for any binary composite with elastically isotropic phases. The results indicate that in the plastic range the thermal and mechanical loading effects are coupled even if the phase properties do not depend on changes in temperature. The derivation is based on a novel decomposition procedure which shows that spatially uniform elastic strain fields can be created in certain heterogeneous media by superposition of uniform phase eigenstrains with local strains, caused by piecewise uniform stress fields which are in equilibrium with prescribed surface tractions. The method is extended to discretized microstructures, and also to the analysis of moisture absorption and phase transformation effects on overall response and on local fields in the two composite materials.
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Wu, Jin Ting, Fen Ye und Yin Ting Wu. „Analysis on Three-Direction Strain of Asphalt Pavement Structure Based on Accelerated Pavement Testing“. Advanced Materials Research 255-260 (Mai 2011): 3426–31. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.3426.
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The internal mechanical response of asphalt pavement structure is difficult to be obtained because of the limitations of theoretical calculation and present testing methods. In order to get practical information of instructure layers, this paper analyzed the cumulative and instantaneous strains of layers’ bottom of semi-rigid base asphalt pavement based on Accelerated Pavement Testing and Fiber Bragg Grating sensors, as well as got the spatial distribution and time-variation law of longitudinal, lateral and vertical strain responses under controlled loading condition. The research result shows that under the moving vehicle loads, there is an obvious alternative property of tension-compression as the strain response of the pavement structure, and different variation shapes of instantaneous stain are in different layers from top to down. Also the measured instantaneous three-direction strain of the bottom of each surface are higher than the calculated values with BISAR, while they anatomizes well in base. This paper can be regarded as useful and tentative research and application on future correlative study.
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Wang, Xingkai, Leibo Song, Caichu Xia, Guansheng Han und Zheming Zhu. „Nonlinear Elasto-Visco-Plastic Creep Behavior and New Creep Damage Model of Dolomitic Limestone Subjected to Cyclic Incremental Loading and Unloading“. Sustainability 13, Nr. 22 (09.11.2021): 12376. http://dx.doi.org/10.3390/su132212376.
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For many rock engineering projects, the stress of surrounding rocks is constantly increasing and decreasing during excavating progress and the long-term operation stage. Herein, the triaxial creep behavior of dolomitic limestone subjected to cyclic incremental loading and unloading was probed using an advanced rock mechanics testing system (i.e., MTS815.04). Then, the instantaneous elastic strain, instantaneous plastic strain, visco-elastic strain, and visco-plastic strain components were separated from the total strain curve, and evolutions of these different types of strain with deviatoric stress increment were analyzed. Furthermore, a damage variable considering the proportion of irrecoverable plastic strain to the total strain was introduced, and a new nonlinear multi-element creep model was established by connecting the newly proposed damage viscous body in series with the Hookean substance, St. Venant body, and Kelvin element. The parameters of this new model were analyzed. The findings are listed as follows: (1) When the deviatoric stress is not more than 75% of the compressive strength, only instantaneous deformation, transient creep, and steady-state creep deformation occur, rock deformation is mainly characterized by the instantaneous strain, whereas the irrecoverable instantaneous plastic strain accounts for 38.02–60.27% of the total instantaneous strain; (2) Greater deviatoric stress corresponds to more obvious creep deformation. The visco-elastic strain increases linearly with the increase of deviatoric stress, especially the irrecoverable visco-plastic strain increases exponentially with deviatoric stress increment, and finally leads to accelerated creep and delayed failure of the sample; (3) Based on the experimental data, the proposed nonlinear creep model is verified to describe the full creep stage perfectly, particularly the tertiary creep stage. These results could deepen our understanding of the elasto-visco-plastic deformation behavior of dolomitic limestone and have theoretical and practical significance for the safe excavation and long-term stability of underground rock engineering.
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Tanaka, Nobuyuki, und Tetsuyuki Kigata. „Instantaneous strain recovery elasticity of polypropylene films.“ Sen'i Gakkaishi 47, Nr. 1 (1991): 1–4. http://dx.doi.org/10.2115/fiber.47.1.
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Song, Yongjun, Leitao Zhang, Huimin Yang, Jianxi Ren und Yongxin Che. „Experimental Study on the Creep Behavior of Red Sandstone under Low Temperatures“. Advances in Civil Engineering 2019 (09.10.2019): 1–9. http://dx.doi.org/10.1155/2019/2328065.
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In cold regions, the deformation characteristics and long-term mechanical properties of rocks under low-temperature conditions are considerably different from those in other regions. To study the deformation characteristics and long-term mechanical properties of rocks in a low-temperature environment and the effect of different temperatures, we perform a multilevel loading-unloading uniaxial creep test on red sandstone samples and obtain the creep curves at different temperatures (20°C, −10°C, and −20°C). The results demonstrate that the total strain at each temperature can be divided into instantaneous and creep strains; the instantaneous strain includes instantaneous elastic and plastic strains, and the creep strain includes viscoelastic and viscoplastic strains. Temperature has a significant effect on the deformation properties of red sandstone. A decrease in temperature reduces the instantaneous and creep deformations of the rocks at all levels of stress. In addition, a decrease in temperature exponentially attenuates the total creep and viscoplastic strains of the rocks. 0°C is a critical point for the reduction of the total creep and viscoplastic strains of the rocks. When the temperature is greater than 0°C, the total creep and viscoplastic strains of the rocks decrease rapidly and linearly with decrease in temperature; however, when the temperature is less than 0°C, the decrease in the total creep and viscoplastic strains of the rocks is slow. The steady-state creep rate of the rock samples decreases with decrease in temperature, whereas the creep duration increases with decrease in temperature, especially in the case of the accelerated creep stage. The accelerated creep durations of the rock samples S4 (20°C) and S7 (–10°C) are 0.07 h and 0.23 h, respectively.
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Yu, Li, Jian Ping Chen und Wei Zheng. „Wavelet Denoising Analysis of Rock’s Stress-Strain Curve under Uniaxial Compression“. Applied Mechanics and Materials 368-370 (August 2013): 1843–47. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.1843.
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Rock stress-strain curve under uniaxial compression is the output of joint action of rock and test system, so it must have certain noise. In order to realize effective denoising processing, the concept of instantaneous deformation modulus has been put forward, and the difference quotient algorithm of instantaneous deformation modulus has been used to enhance noise. After wavelet analysis and wavelet packet analysis of rock stress consequence and instantaneous deformation modulus respectively, the results of different denoising schemes have been statistically analyzed, this analysis shows that the wavelet packet analysis of instantaneous deformation modulus can achieve optimal denoising effect.
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Fu, Chunyu, Dawei Tong und Yuyang Wang. „Assessing the Instantaneous Stiffness of Cracked Reinforced Concrete Beams Based on a Gradual Change in Strain Distributions“. Advances in Materials Science and Engineering 2020 (27.02.2020): 1–10. http://dx.doi.org/10.1155/2020/7453619.
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Concrete cracking causes a gradual change in strain distributions along the cross section height of reinforced concrete beams, which will finally affect their instantaneous stiffness. A method for assessing the stiffness is proposed based on the gradual change, which is considered through modeling different strain distributions for key sections in cracked regions. Internal force equilibria are adopted to find a solution to top strains and neutral axes in the models, and then the inertias of the key sections are calculated to assess the beam stiffness. The proposed method has been validated using experimental results obtained from tests on five reinforced concrete beams. The predicted stiffness and displacements are shown to provide a good agreement with experimental data. The instantaneous stiffness is proven to greatly depend on the crack number and depth. This dependence can be exactly reflected by the proposed method through simulating the gradual change in concrete strain distributions.
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Koyankin, A. A., V. M. Mitasov, I. Ya Petuhova und T. A. Tshay. „STRESS-STRAIN STATE OF PREFABRICATED MONOLITHIC BENDING ELEMENT AT GRADUAL INSTALLATION AND LOADING“. Vestnik Tomskogo gosudarstvennogo arkhitekturno-stroitel'nogo universiteta. JOURNAL of Construction and Architecture, Nr. 6 (29.12.2019): 101–14. http://dx.doi.org/10.31675/1607-1859-2019-21-6-101-114.
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The stress-strain state of the prefabricated monolithic element depends on its gradual installation and loading. Regulatory documents of the Russian Federation indicate the need to calculate precast-monolithic structures for two stages of construction: before and after the specified monolithic concrete strength acquired. In this case, the stress-strain state that appeared in the prefabricated elements before the specified monolithic concrete strength should be considered. However, the construction and loading stages at issue and accumulation of stresses and strains are not disclosed in the regulatory documents. In addition, this problem is insufficiently studied. In this regard, the aim of this paper is to study the pre-loading effect of the prefabricated element on its stress-strain state and the load-bearing capacity. During the experiments, a pre-loaded prefabricated part is studied. The obtained results are compared with instantaneously loaded test samples. Other parameters of the experimental models are completely identical. In all, 5 samples are tested (step-by-step loading of 3 samples and instantaneous loading of 2 samples). It is shown that pre-loading of the preloaded prefabricated part significantly affects the stress-strain state of the whole structure and its total load-bearing capacity.
Dissertationen zum Thema "Instantaneous strain"
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Afara, Isaac Oluwaseun. „Near infrared spectroscopy for non-destructive evaluation of articular cartilage“. Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/53217/1/Isaac_Afara_Thesis.pdf.
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There is a need for an accurate real-time quantitative system that would enhance decision-making in the treatment of osteoarthritis. To achieve this objective, significant research is required that will enable articular cartilage properties to be measured and categorized for health and functionality without the need for laboratory tests involving biopsies for pathological evaluation. Such a system would provide the capability of access to the internal condition of the cartilage matrix and thus extend the vision-based arthroscopy that is currently used beyond the subjective evaluation of surgeons. The system required must be able to non-destructively probe the entire thickness of the cartilage and its immediate subchondral bone layer.
In this thesis, near infrared spectroscopy is investigated for the purpose mentioned above. The aim is to relate it to the structure and load bearing properties of the cartilage matrix to the near infrared absorption spectrum and establish functional relationships that will provide objective, quantitative and repeatable categorization of cartilage condition outside the area of visible degradation in a joint. Based on results from traditional mechanical testing, their innovative interpretation and relationship with spectroscopic data, new parameters were developed. These were then evaluated for their consistency in discriminating between healthy viable and degraded cartilage. The mechanical and physico-chemical properties were related to specific regions of the near infrared absorption spectrum that were identified as part of the research conducted for this thesis. The relationships between the tissue's near infrared spectral response and the new parameters were modeled using multivariate statistical techniques based on partial least squares regression (PLSR).
With significantly high levels of statistical correlation, the modeled relationships were demonstrated to possess considerable potential in predicting the properties of unknown tissue samples in a quick and non-destructive manner.
In order to adapt near infrared spectroscopy for clinical applications, a balance between probe diameter and the number of active transmit-receive optic fibres must be optimized. This was achieved in the course of this research, resulting in an optimal probe configuration that could be adapted for joint tissue evaluation. Furthermore, as a proof-of-concept, a protocol for obtaining the new parameters from the near infrared absorption spectra of cartilage was developed and implemented in a graphical user interface (GUI)-based software, and used to assess cartilage-on-bone samples in vitro. This conceptual implementation has been demonstrated, in part by the individual parametric relationship with the near infrared absorption spectrum, the capacity of the proposed system to facilitate real-time, non-destructive evaluation of cartilage matrix integrity.
In summary, the potential of the optical near infrared spectroscopy for evaluating articular cartilage and bone laminate has been demonstrated in this thesis. The approach could have a spin-off for other soft tissues and organs of the body. It builds on the earlier work of the group at QUT, enhancing the near infrared component of the ongoing research on developing a tool for cartilage evaluation that goes beyond visual and subjective methods.
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Le, Roy Robert. „Déformations instantanées et différées des bétons à hautes performances“. Phd thesis, Marne-la-vallée, ENPC, 1995. http://www.theses.fr/1995ENPC9534.
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On présente ici deux types de modélisations, ainsi que de nombreuses données expérimentales, portant sur les déformations des bétons et en particulier celles des bétons à hautes performances. La première a pour but de prévoir les amplitudes des déformations instantanées, de retrait endogène et de fluage propre, en fonction de la formulation. On utilise pour cela une approche par homogénéisation, en adaptant le modèle bisphère de Hashin au calcul du module du béton. La démarche de modélisation, fondée sur la prise en compte de la compacité réelle du squelette granulaire, aboutit à une géométrie trisphère. On fait le choix, après l'avoir justifié, de fixer les coefficients de Poisson à un cinquième. Puis, on applique le modèle trisphère au calcul des amplitudes de fluage propre et de retrait endogène. Les paramètres principaux de formulation (rapports eau sur ciment, fumée de silice sur ciment, proportion granulaire, classe du ciment) sont pris en compte. L'approche appliquée au fluage est confortée par un calcul viscoélastique linéaire. Dans la deuxième approche, on propose un modèle simplifié, de type réglementaire, pour le calcul des déformations des bétons à hautes performances en fonction du temps, et d'un nombre limité de paramètres. Les apports principaux de la modélisation concernent la prise en compte de l'autodessiccation, de la maturité et de la résistance du matériau au moment du chargement. Le modèle a été validé d'après de nombreuses données, et pour des bétons de maturités très variables au chargement, variant de seize heures à plus de deux ans. Elaboré dans le cadre de l'Association Française pour la Recherche et l'Etude des Matériaux et des Structures (AFREM), le modèle est proposé comme annexe au règlement français de béton précontraint (BPEL), pour les bétons couvrant la gamme B60-B80This thesis proposes two types of modelling, together with a long series of experimental date, for the instantaneaous and time-dependent strains of high performance concrete. The first model deals with instantaneous, autogenous shrinkage and basic creep deformations of high performance concrete with respect to mix-design parameters. To the end, a homogenization approach based on Hashin’s spheres model for the modulus, is adopted and modified to take into account the effective maximum packing density of the aggregates. This leads to a three-sphere model. After justification, the Poisson’s ratio of each phase is set at a constant value of 0,2. This model is consequently applied to calculate the long-term amplitude of autogenous shrinkage and basic-creep. The creep results obtained are compared with visco-elastic calculation, which allows the adopted approach to be confirm. The main mix-design parameters are taken into account (water/cement ratio, silica fume/cement ratio, aggregate concentration, maximum packing density of the agregate, cement strength). The second research part deals with a simplified model for design code purposes. It allows the calculation of high performance concrete strains as a function of time, and a limited number of parameters. In particular it accounts for the self-dessication, the maturity and the strength of the concrete at the loading time. This model was validated against extensive experimental data, covering the marurity rang from sixteen hours to two years. The model was established within the framework of the French Structures and Materials Research Association (AFREM) and is proposed in addition to the French Prestressed Concrete French Code (BPEL) for concrete covering the strength range from 40 to 80 Mega-Pascals
Buchteile zum Thema "Instantaneous strain"
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Kanai, Hiroshi, Hideyuki Hasegawa, Noriyoshi Chubachi, Yoshiro Koiwa und Motonao Tanaka. „Noninvasive Evaluation of Spatial Distribution of Local Instantaneous Strain Energy in Heart Wall“. In Acoustical Imaging, 187–92. Boston, MA: Springer US, 1997. http://dx.doi.org/10.1007/978-1-4419-8588-0_30.
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Kholoptsev, A. V., T. Ya Shul’ga, O. Ye Shchodro und S. A. Podporin. „The Influence of Anticyclonic Movement Over the Sea of Azov on Variations of Maximum Instantaneous Current Speed in the Kerch Strait During 1948–2017 Ice Seasons“. In Springer Proceedings in Earth and Environmental Sciences, 1–14. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-11533-3_1.
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Reed, Martin B. „Instantaneous rate of change: the derivative“. In Core Maths for the Biosciences. Oxford University Press, 2011. http://dx.doi.org/10.1093/hesc/9780199216345.003.0013.
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This chapter talks about the mathematical rate-of-change theory, in other words, calculus, which has two branches: differential calculus and integral calculus. It considers differential equation as the most powerful use of calculus in the biosciences as it is an equation involving the derivative of a function and the function itself. It also examines how epidemiologists come up with predictions for the likely course of a new strain of influenza by modelling the instantaneous rate at which the disease is spreading. The chapter clarifies that rate-of-change involves an independent variable and a dependent variable, such as the velocity of a moving object is the rate-of-change of its position. It illustrates this topic using the Michaelis–Menten equation as this describes an enzyme-catalysed biochemical reaction wherein the rate of reaction v depends on the substrate concentration s.
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Temkin, Sefton D. „At North College Hill“. In Creating American Reform Judaism, 187–89. Liverpool University Press, 1998. http://dx.doi.org/10.3828/liverpool/9781874774457.003.0030.
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This chapter details Isaac Mayer Wise’s move at a large farm between North College Hill and Mount Healthy, and made it his principal residence. The farm lay nine miles north of Cincinnati. It is unusual, even in these days of instantaneous communications, for a clergyman to live at such a distance from the scene of his activities; in 1861 it must have been unprecedented. His congregation did not demur at Wise’s removing himself a distance of nine miles, and Wise, of whose endurance as a traveller there is ample evidence, presumably found driving to and from the city no strain. There is no information as to the role played by Mrs Wise in the decision, peculiarly within the concerns of a wife and mother, to move the family home. Family recollections suggest that the decision was that of the husband, and that the wife acquiesced reluctantly.
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Grandjean, Nicolas, Benjamin Damilano, und Jean Massies. „The growth of low-dimensional nitrides by molecular beam epitaxy“. In Low-Dimensional Nitride Semiconductors, 121–50. Oxford University PressOxford, 2002. http://dx.doi.org/10.1093/oso/9780198509745.003.0006.
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Abstract Molecular beam epitaxy (MBE) is the technique of choice for the growth of low-dimensional semiconductor hetero structures. The ultra-high vacuum environment of MBE allows the use of an in situ electron probe like reflection high-energy electron diffraction (RHEED). RHEED is a powerful tool for controlling the growth in real time [1]. It allows the precise measurement of the growth rate [2), the determination of ternary alloy composition [3), and the investigation of strain relaxation during heteroepitaxy [4, 5). MBE is also well suited for achieving abrupt interfaces. This is the consequence of molecular flux regime, which authorizes an instantaneous flux switching (simply using a shutter), and growth conditions far from equilibrium that avoid strong intermixing at the interfaces. For instance, the substrate temperatures used in MBE are much lower than those currently reported for metal-organics chemical vapor deposition (MOCVD) growth.
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NAKATA, Masayuki, Tsukasa YURI und Hiroshi OIKAWA. „INSTANTANEOUS STRAIN ASSOCIATED WITH STRESS CHANGES IN HIGH-TEMPERATURE CREEP OF Al-0.3 mol% Mg ALLOY“. In Design & Analysis, 1615–20. Elsevier, 1989. http://dx.doi.org/10.1016/b978-1-4832-8430-9.50149-0.
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Saltzman, W. Mark. „Cell and Tissue Mechanics“. In Tissue Engineering. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780195141306.003.0010.
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Mechanics is the branch of physics that is concerned with the action of forces on matter. Tissue engineers can encounter mechanics in various settings. Often, the mechanical properties of replacement biological materials must replicate the normal tissue: for example, there is limited use for a tissue-engineered bone that cannot support the load encountered by its natural counterpart. In addition, the mechanical properties of cells and cell–cell adhesions can determine the architecture of a tissue during development. This phenomenon can sometimes be exploited, since the final form of engineered tissues depends on the forces encountered during assembly and maturation. Finally, the mechanics of individual cells—and the molecular interactions that restrain cells—are important determinants of cell growth, movement, and function within an organism. This chapter introduces the basic elements of mechanics applied to biological systems. Some examples of biomechanical principles that appear to be important for tissue engineering are also provided. For further reading, comprehensive treatments of various aspects of biomechanics are also available. Consider an elongated object—for example, a segment of a biological tissue or a synthetic biomaterial—that is fixed at one end and suddenly exposed to a constant applied load. The material will change or deform in response to the load. For some materials, the deformation is instantaneous and, under conditions of low loading, deformation varies linearly with the magnitude of the applied force: . . . σ[≡F/A]= Eε (5-1) . . . where σ is the applied stress and ε is the resulting strain. This relationship is called Hooke’s law, after the British physicist Robert Hooke, and it describes the behavior of many elastic materials, such as springs, which deform linearly upon loading and recover their original shape upon removal of the load. The Young’s modulus or tensile elastic modulus, E, is a property of the material; some typical values are provided in Table 5.1. Not all elastic materials obey Hooke’s law (for example, rubber does not); some materials will recover their original shape, but strain is not linearly related to stress. Fortunately, many interesting materials do follow Equation 5-1, particularly if the deformations are small.
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Han, Chang Dae. „Kinematics and Stresses of Deformable Bodies“. In Rheology and Processing of Polymeric Materials: Volume 1: Polymer Rheology. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195187823.003.0007.
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The form of kinematics to be used for the description of a deformation process is largely determined by the kind of mechanical response that is being described. To describe the mechanical response of purely viscous fluids it is convenient to use coordinates, which are fixed in space, since purely viscous fluids have no past memory and therefore remain in the deformed state when loads are removed. In other words, the mechanical response of purely viscous fluids is determined solely by the instantaneous values of the time rate of deformation. However, in order to describe the deformation of a viscoelastic fluid it is necessary to follow a given material element with time as it moves to define a suitable measure of deformation that always refers to the same material element as time varies. The reason is that when a material element undergoes a finite deformation the coordinate positions of the given material element (with respect to a fixed origin) will vary. Hence, any measure of deformation defined in terms of infinitesimal deformation of fixed coordinate positions loses its physical significance since it will not always be associated with the same material element. In this chapter, we introduce some basic concepts of the kinematics and stresses of a deformable body from the point of view of continuum mechanics, and discuss various representations of a deformation process in terms of the deformation (or strain) tensor and the rate-of-deformation (or rate-of-strain) tensor. In order to help the readers follow the material in the text, the elementary properties of second-order tensors are presented in Appendix 2A. In this section, we briefly describe the motion of a body, which consists of a set of particles (or “elements”), sometimes called “material points” (or “material elements”) (Jaunzemis 1967). Let X(Xi ; i = 1, 2, 3) be the particles P of the body B in some reference configuration κ at time t = 0 (i.e., undeformed state) and then we have. . . X = κ(P). . .in which κ describes the shape of the body B in the undeformed state, which in general is known to an observer.
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Bauer, Mark S. „Thomas Chatterton (1752–1770)“. In A Mind Apart, 120–21. Oxford University PressNew York, NY, 2008. http://dx.doi.org/10.1093/oso/9780195336405.003.0039.
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Abstract Sunday, A Fragment Hervenis, harping on the hackneyed text, By disquisitions is so sore perplexed, He stammers,—instantaneously is drawn A bordered piece of inspiration-lawn, Which being thrice unto his nose applied, Into his pineal gland the vapours glide; And now again we hear the doctor roar On subjects he dissected thrice before. I own at church I very seldom pray, For vicars, strangers to devotion, bray. Sermons, though flowing from the sacred lawn, Are flimsy wires from reason’s ingot drawn; And, to confess the truth, another cause My every prayer and adoration draws: In all the glaring tinctures of the bow, The ladies front me in celestial row. (Though, when black melancholy damps my joys, I call them nature’s trifles, airy toys; Yet when the goddess Reason guides the strain, I think them, what they are, a heavenly train.) The amorous rolling, the black sparkling eye, The gentle hazel, and the optic sly; The easy shape, the panting semi-globes, The frankness which each latent charm disrobes; The melting passions, and the sweet severe, The easy amble, the majestic air; The tapering waist, the silver-mantled arms, All is one vast variety of charms. Say, who but sages stretched beyond their span, Italian singers, or an unmanned man, Can see Elysium spread upon their brow, And to a drowsy curate’s sermon bow?
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Kobayashi, Shiro, Soo-Ik Oh und Taylan Altan. „Thermo-Viscoplastic Analysis“. In Metal Forming and the Finite-Element Method. Oxford University Press, 1989. http://dx.doi.org/10.1093/oso/9780195044027.003.0015.
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The main concern here is the analysis of plastic deformation processes in the warm and hot forming regimes. When deformation takes place at high temperatures, material properties can vary considerably with temperature. Heat is generated during a metal-forming process, and if dies are at a considerably lower temperature than the workpiece, the heat loss by conduction to the dies and by radiation and convection to the environment can result in severe temperature gradients within the workpiece. Thus, the consideration of temperature effects in the analysis of metal-forming problems is very important. Furthermore, at elevated temperatures, plastic deformation can induce phase transformations and alterations in grain structures that, in turn, can modify the flow stress of the workpiece material as well as other mechanical properties. Since materials at elevated temperatures are usually rate-sensitive, a complete analysis of hot forming requires two considerations—the effect of the rate-sensitivity of materials and the coupling of the metal flow and heat transfer analyses. A material behavior that exhibits rate sensitivity is called viscoplastic. A theory that deals with viscoplasticity was described in Chap. 4. It was shown that the governing equations for deformation of viscoplastic materials are formally identical to those of plastic materials, except that the effective stress is a function of strain, strain-rate, and temperature. The application of the finite-element method to the analysis of metal-forming processes using rigid-plastic materials leads to a simple extension of the method to rigid-viscoplastic materials. The importance of temperature calculations during a metal-forming process has been recognized for a long time. Until recently, the majority of the work had been based on procedures that uncouple the problem of heat transfer from the metal deformation problem. Several researchers have used the following approach. They determined the flow velocity fields in the problem either experimentally or by calculations, and they then used these fields to calculate heat generation. Examples of this approach are the works of Johnson and Kudo on extrusion, and of Tay et al. on machining. Another approach uses Bishop’s numerical method in which heat generation and transportation are considered to occur instantaneously for each time-step with conduction taking place during the time-step.
Konferenzberichte zum Thema "Instantaneous strain"
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Soo, S., und L. T. Adams. „The Instantaneous Strain of Frozen Sand“. In International Arctic Technology Conference. Society of Petroleum Engineers, 1991. http://dx.doi.org/10.2118/22148-ms.
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2
Isakov, M., V. T. Kuokkala und R. Ruoppa. „Instantaneous strain rate sensitivity of metastable austenitic stainless steel“. In DYMAT 2009 - 9th International Conferences on the Mechanical and Physical Behaviour of Materials under Dynamic Loading. Les Ulis, France: EDP Sciences, 2009. http://dx.doi.org/10.1051/dymat/2009205.
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3
Ferreira, Jetson L. P. N. D. S. M. V. S. R. S. G. T. B. „DETERMINATION METHODOLOGY OF STRESS-STRAIN CURVE FOR DIFFERENT HARDENING MODELS AND INSTANTANEOUS STRAIN HARDENING EXPONENT VIA PYTHON“. In 58º Seminário de Laminação, Conformação de Metais e Produtos. São Paulo: Editora Blucher, 2023. http://dx.doi.org/10.5151/2594-5297-40003.
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4
Ohguchi, Ken-Ichi, Katsuhiko Sasaki und Setsuo Aso. „Evaluation of Time-Independent and Time-Dependent Strains of Lead-Free Solder by Stepped Ramp Loading Test“. In ASME 2007 InterPACK Conference collocated with the ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ipack2007-33663.
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This paper proposes a method which can estimate essential material constants of an elasto-plastic-creep constitutive model for lead-free solders by conducting only a tensile test. The test employs a stepped ramp wave loading which repeats instantaneous straining and strain maintaining. The time-independent strains can be evaluated by using the stress-strain relations at the instantaneous straining parts, while the time-dependent strain can be evaluated by using the stress-time relations during the strain maintaining parts. Based on the results of the evaluations, the material constants of the elasto-plastic-creep models are estimated. Simulations of the viscoplastic deformations of Sn-3.0Ag-0.5Cu solder alloy were also conducted to verify the validity of the proposed method.
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Wu, Shaoju, Wei Zhao, Saeed Barbat, Jesse Ruan und Songbai Ji. „Instantaneous Brain Strain Estimation for Automotive Head Impacts via Deep Learning“. In 65th Stapp Car Crash Conference. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2022. http://dx.doi.org/10.4271/2021-22-0006.
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Faidley, LeAnn, David Macias und Eric Harrington. „Cyclic Actuator Behavior of Ferrogels“. In ASME 2008 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2008. http://dx.doi.org/10.1115/smasis2008-530.
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Ferrogels are low modulus polymer materials with embedded magnetic powder filler giving them the capability to strain in a magnetic field. The large strains, high energy densities, and fast response that have been reported make these materials attractive for actuator applications, however, a full understanding of the dynamic behavior is lacking. In this work the following behaviors are characterized: (1) the effect of gravity is determined by comparing behavior in two configurations, (2) the effect of compositions is investigated for 9 samples of different matrix and filler compositions, (3) the effect of frequency is determined for sinusoidal inputs between 0.1 and 80 Hz and, (4) the instantaneous and long-term strain behavior is discussed based on the ferrogel response to step inputs of magnitudes up to 2200 Gauss. It was found that the highest strains are achieved for the most flexible samples with the highest amount of magnetic filler tested in a configuration in which gravity acts in opposition to the magnetic attraction. Lower frequencies allow for larger strains because more time is allowed for visco-elastic motion. Finally, the step response shows that the strain occurs in two types. First, is an instantaneous strain; second, is a visco-elastic deformation that takes place over an extended period of time.
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Troyer, Kevin L., und Christian M. Puttlitz. „Comparison of a Novel Nonlinear Viscoelastic Finite Ramp Time Correction Method to a Heaviside Step Assumption“. In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53186.
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Connective soft tissues exhibit time-dependent, or viscoelastic, behavior. In order to characterize this behavior, stress relaxation experiments can be performed to determine the tissue’s relaxation modulus. Theoretically, the relaxation modulus describes the stress relaxation behavior of the tissue in response to an instantaneous (step) application of strain. However, a step increase in strain is experimentally impossible and a pure ramp load is intractable due to the inertial limitations of the testing device. Even small deviations from an instantaneous strain application may cause significant errors in the determination of the tissue’s relaxation modulus.
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Hata, Toshiaki. „STRESS-FOCUSING EFFECTS IN A SPHERICAL INCLUSION WITH INSTANTANEOUS TRANSFORMATION STRAIN IN INFINITE ELASTIC DOMAIN“. In Proceedings of the Second International Conference. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812776228_0021.
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Probert, Molly A., Harry E. Coules und Christopher E. Truman. „Effects of Crack Introduction History on Fracture Initiation in Residually Stressed Components“. In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84414.
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If a crack is introduced progressively into an elastic-plastic material containing a residual stress field, the incremental relaxation of the residual stress field causes the formation of a plastic wake along the crack boundaries. This leads to the reduction in the J parameter for a crack of a given size, compared to a crack with the same dimensions which has been introduced instantaneously, having the crack faces released simultaneously along the whole length, a 40% reduction is observed in the current analysis. This reduction in J is due to the dissipation of strain energy which is otherwise available for further crack extension, as in the instantaneously introduced crack. This is important for the current J-based fracture assessment common in the nuclear and petrochemical industries such as EDF Energy’s R6 and BS7910:2013 as they currently assume instantaneous insertion of cracks as this is inherently more conservative. Although many studies demonstrating this effect in FE are available, there is little experimental evidence for this phenomenon. Especially those including rigorous comparisons with specimens that have been ‘instantaneously’ cracked. This may be due to the difficulty inherent in manufacturing such a specimen as manufacturing processes rely on the incremental removal of material. The aim of this paper is to detail analysis of a novel method of crack introduction that aims to replicate the deformation behavior of an instantaneously introduced crack tip in a model that has had the nodes released in a progressive manner. This will allow specimens to be machined in a way that replicates ‘instantaneous’ cracking allowing for experimental techniques to be developed to display the difference between instantaneous and progressively introduced cracks.
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Embong, A. H., A. M. Al-Jumaily, Giri Mahadevan, Shukei Sugita und Andrew Lowe. „Patient-Specific Aneurysms Rupture Prediction Using CFD Modelling With Strain Energy Function“. In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63859.
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This paper proposes a new Patient-Specific Aneurysm CFD Model (PSAM) which is based on the energy strain function combined with dilated vessel wall stress-strain relationship to predict aneurysm rupture. The PSAM relies on the available mechanical properties and parameters obtained from a personalized model. A personalized model is developed based on instantaneous arterial deformations obtained from Doppler Ultrasound (US) images at 6–9 MHz. It is shown that PSAM has the ability to correlate the deformation wall energy based on continuous patient-specifics in predicting rupture.
Berichte der Organisationen zum Thema "Instantaneous strain"
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Bubenik und Nestleroth. L51619 Effects of Loading on the Growth Rates in Deep Stress-Corrosion Cracks. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), August 1990. http://dx.doi.org/10.55274/r0010094.
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With the development of improved techniques for detection of stress corrosion cracks in existing pipelines, the pipeline industry is faced with the problem of estimating the growth rates of these cracks. Current efforts in model development are addressing the problem but, in order to verify these models, accurate average crack velocity data are needed (average crack velocity being defined as the average rate of crack growth with time, crack velocity is the instantaneous rate of crack tip dissolution.) Currently available data are limited and are based primarily on either slow-strain rate tests or tapered tensile tests. The loading conditions in the former are unrepresentative of actual operating conditions while the crack depths in the latter are much shallower than those observed in service. Some fracture mechanics data also are available for this system but the specimen and crack geometry used in these tests are not similar to the geometry of the field failures*. In addition, results of recent PRCI research suggest that the stress intensity parameter, K, which is used to relate different cracking geometries, is a poor crack driving force parameter for SCC in line pipe steels. The overall objective of this work is to obtain accurate average crack velocity data as a function of crack depth and loading conditions. The program is divided into two tasks: Task 1 - Effect of Crack Depth and Cyclic Loading Conditions on Crack Growth and Task 2 - Inhibition of Crack Growth.