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1
Romanov, O. V. "On the influence of the stress state on the deformation of construction materials." Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, no. 4 (2021): 66–69. http://dx.doi.org/10.17721/1812-5409.2021/4.10.
Повний текст джерелаАнотація:
The question of the influence of the type of stress state (TSS) on the process of scleronomic and rheonomic deformation of structural materials under simple and close to simple loading conditions is considered. The parameters characterizing the TSS are indicated. This is a parameter (indicator) of the rigidity of the stress state, which reflects the influence of the first invariant of the stress tensor and is, with an accuracy of a constant factor, the ratio of the hydrostatic component of the stress tensor to its deviator component. The influence of the third invariant of stress tensors is taken into account by a number of parameters – the Nadai-Lode parameter, as well as the TSS angle in its various interpretations. A variant of taking this influence into account by introducing the governing equation of state of the function with the parameter of the TSS angle is shown. This function is determined based on analysis of basic tensile and torsion experiments. It is shown that taking into account VNS increases the accuracy of the calculation and improves the agreement between the calculation results and experiment.
2
Zouani, Abdelkrim, Thang Bui-Quoc, and Marie Bernard. "Fatigue Life Parameter for Type 304 Stainless Steel Under Biaxial-Tensile Loading at Elevated Temperature." Journal of Engineering Materials and Technology 121, no. 3 (July 1, 1999): 305–12. http://dx.doi.org/10.1115/1.2812379.
Повний текст джерелаАнотація:
This paper describes a damage Parameter for predicting fatigue life under biaxial-tensile loadings. Several studies have focussed in the past on the situations where the in-plane biaxial stress ratio is negative; however, little attention has been paid for the cases involving both principal stresses in tension. A new testing method is used to carry out biaxial fatigue tests, at room and 427°C, on Type 304 stainless steel for different positive values of the stress ratio. In the experimental procedure, a disk-shaped specimen was used in connection with a spatial-arms mechanism which converts the uniaxial force generated by a conventional testing machine to radial forces extending the disk specimen. A modified virtual strain energy parameter is then suggested to normalize fatigue data obtained under a wide range of stress states. The proposed parameter accounts for the mean stress and the mean strain effects in an explicit form. In addition, the COD equivalent stress and strain concepts are adopted to account for the stress state biaxiality. The predictions of the proposed parameter are compared with the obtained experimental data and the correlation between the applied stress states and the experimental fatigue lives is discussed.
3
Gao, Hua Xi, Min Jie Wen, and Rong Xin Li. "Frequency Response of a Fractional Derivative Viscoelastic Type Lined Tunnel with Partial Sealing." Advanced Materials Research 368-373 (October 2011): 2692–97. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.2692.
Повний текст джерелаАнотація:
Based on Biot saturated soil theory, steady state dynamic response of the system is studied in the frequency domain when the inner boundary of a fractional derivative viscoelastic type circular lined tunnel is under the axisymmetric load and fluid pressure respectively. On the basis of introducing a partial permeable boundary condition, the solutions of stress, displacement and pore pressure of the lining and saturated soil are obtained by the inner boundary of the lining and continuity conditions of the interface, besides, the stress-displacement constitutive behavior of the lining is described by fractional derivative viscoelastic constitutive model. The influence of physical parameter on the system response is investigated. It is shown that the order of fractional derivative model has a great influence on the system dynamic response, and it depends on material parameter of the lining when the inner boundary of lining is subjected to axisymmetric load. The permeability parameter of lining has significant effects on system response induced by fluid pressure.
4
Shiravi, Shahram, and Arash Razmkhah. "Parametric stress-strain analysis for upstream slope of the asphaltic concrete core rockfill dams in static state." Nexo Revista Científica 34, no. 06 (December 31, 2021): 1800–1818. http://dx.doi.org/10.5377/nexo.v34i06.13161.
Повний текст джерелаАнотація:
In this study, the effects of various geometric parameters of a dam in 2D static analysis of stress-strain on the upstream slope of the asphaltic concrete core rockfill dams were investigated. For this purpose, first the geometric characteristics of a large number of world's dams were collected and assessed, then by geometric modeling of these dams, many numerical models were developed for static analysis using GeoStudio software in eight height classes, three cases of upstream and downstream slopes, three different shape and thickness of the asphaltic concrete core under different Impounding states including "Full Reservoir", "Half full Reservoir", "End of construction and "Rapid Drawdown on a rigid type of foundation. The results of this study demonstrated that in four different construction and impounding states and in three different cases of slopes, Increasing the height parameter, causes increasing the Maximum total stress, Maximum total strain, Shear strain and Maximum shear stress for all construction and impounding states. The Maximum total stress decreased for all operating situations as the upstream slope reduced. According to the obtained results from the static stress-strain analysis, increasing both vertical and inclined asphaltic concrete core thicknesses, leads to decreasing the Maximum shear stress in Full Reservoir state but it increases in other state of impoundment. Moreover, by comparing the displacements related to specified points on the upstream slopes, increasing the height parameter, leads to increasing both horizontal and vertical displacements, the volumetric strain, deviator strain and deviator stress for all impounding conditions. In the following, the additional results were provided along with diagrams for further analysis.
5
Vulliet, Laurent, and Kolumban Hutter. "Viscous-type sliding laws for landslides." Canadian Geotechnical Journal 25, no. 3 (August 1, 1988): 467–77. http://dx.doi.org/10.1139/t88-052.
Повний текст джерелаАнотація:
Sliding of a moving soil mass along a basal surface is analyzed and viscous-type sliding laws are presented. They relate the relative sliding velocity at the base—or at an interface—to the state of stress at this surface. Examples of practical parameter determination illustrate the suitability of this approach; two landslides (in Switzerland and in France) provide the data for this purpose. A third site (La Frasse, Switzerland) serves as an example of three-dimensional analysis of creeping slopes using the proposed formulation. Comparison of computed and measured velocity distributions shows the method to be promising. Key words: landslides, creep, sliding law, time dependence, interface.
6
He, Bin, Chenghong Zhang, Yanmin Zhou, and Zhipeng Wang. "A Computing Method to Determine the Performance of an Ionic Liquid Gel Soft Actuator." Applied Bionics and Biomechanics 2018 (2018): 1–11. http://dx.doi.org/10.1155/2018/8327867.
Повний текст джерелаАнотація:
A new type of soft actuator material—an ionic liquid gel (ILG) that consists of BMIMBF4, HEMA, DEAP, and ZrO2—is polymerized into a gel state under ultraviolet (UV) light irradiation. In this paper, we first propose that the ILG conforms to the assumptions of hyperelastic theory and that the Mooney-Rivlin model can be used to study the properties of the ILG. Under the five-parameter and nine-parameter Mooney-Rivlin models, the formulas for the calculation of the uniaxial tensile stress, plane uniform tensile stress, and 3D directional stress are deduced. The five-parameter and nine-parameter Mooney-Rivlin models of the ILG with a ZrO2 content of 3 wt% were obtained by uniaxial tensile testing, and the parameters are denoted as c10, c01, c20, c11, and c02 and c10, c01, c20, c11, c02, c30, c21, c12, and c03, respectively. Through the analysis and comparison of the uniaxial tensile stress between the calculated and experimental data, the error between the stress data calculated from the five-parameter Mooney-Rivlin model and the experimental data is less than 0.51%, and the error between the stress data calculated from the nine-parameter Mooney-Rivlin model and the experimental data is no more than 8.87%. Hence, our work presents a feasible and credible formula for the calculation of the stress of the ILG. This work opens a new path to assess the performance of a soft actuator composed of an ILG and will contribute to the optimized design of soft robots.
7
Lomakin, E. V., and P. V. Tishin. "Constitutive relations for materials with strain state dependent properties." PNRPU Mechanics Bulletin, no. 1 (December 15, 2021): 52–62. http://dx.doi.org/10.15593/perm.mech/2021.1.06.
Повний текст джерелаАнотація:
Many materials demonstrate a dependence of mechanical properties on the type of stressed or deformed states. This is most noticeable in the dependence of the processes of shear and bulk deformation. Such materials include rocks, structural graphite, concrete, some grades of steel, cast iron, and aluminum. The main properties of these materials are an absence of a "single curve" relationship between the intensity of stresses and the intensity of deformations. Under shear conditions, bulk deformations can occur. Such materials can be described by constitutive equations that depend on the parameter of the type of a stress state, which is the ratio of the first invariant of the stress tensor to the stress intensity. Thus, these defining relations give the dependence of the strain tensor components on the stress tensor components. Such defining relations can be quite cumbersome, and therefore do not allow an analytical treatment to obtain defining relations that give the dependence of the components of the stress tensor on the components of the strain tensor. The paper proposes the constitutive relations obtained from the analysis of test results of various materials, which properties depend on the type of deformed state. Conditions are derived for material constants that ensure the uniqueness of the solution of boundary value problems. Based on experimental data obtained under the conditions of the proportional loading of various rocks: limestone and talcochlorite, as well as the results of mechanical tests of several grades of concrete, the constants of the mathematical model are determined. The results of the experimental studies are compared with theoretical dependencies predicted by the model. The limited applicability of the proposed constitutive relations is established.
8
Skoblo, Tamara, Ivan Rybalko, Aleksandr Tihonov, and Taras Maltsev. "Evaluation of the stress state of a cultivator blade in production and operation." Research in Agricultural Engineering 66, No. 2 (June 29, 2020): 60–65. http://dx.doi.org/10.17221/8/2020-rae.
Повний текст джерелаАнотація:
The aim of the work was to determine the quality of a new and used cultivator blade to assess the condition of the metal with the development of rejection norms of its variability in a magnetic parameter – coercive force using various types of equipment – coercimeters. The new cultivator blade shows the highest level of coercive force that is characteristic of its right and left parts and its decrease occurs towards the toe. After operation, variability is noted, characterised by both an increase and a decrease in the indicators of the coercive force. Rejection norms of the metal state, which determine the possibility of restoring a worn cultivator blade, which can also provide satisfactory indicators for their further use in operation, have been proposed. For restoration, it is recommended to use a cultivator blade made of low carbon steel, the zones of which should not change the level of the coercive force > 10.0% during operation. It is not recommended to restore those blades in which, after increasing the indicators, they then decreased to (< 5.0%) and are characterised by close values of the indicators.
9
LAGUNOVA, Yuliya Andreevna, Stanislav Anatol’evich MAYOROV, and Gennadiy Alexeevich BOYARSKIH. "Statistical analysis of stress-strain state of bearing jaw crusher." NEWS of the Ural State Mining University 1, no. 2 (June 15, 2020): 159–71. http://dx.doi.org/10.21440/2307-2091-2020-2-159-171.
Повний текст джерелаАнотація:
The relevance of the work. When creating particularly large machines and systems, in the case of their 3D modeling and detailed study, the load on the central processor of the computer, as well as on the graphic and RAM modules, increases, which significantly slows down the design process and calculations. In the article, a statistical analysis of the stress-strain state of the jaw crusher bearing is carried out to establish the correspondence of the theoretical and actual structural models taking into account all workloads. The objectives of the study. Consider the task of selecting a simpler and “easier” for the calculation model programs, not difficult to parameterize, compared with the original bearing model, but providing accuracy in the calculation in an acceptable range of errors. To analyze the stress-strain state of the bearing assembly with various geometric parameters. Research methodology. In the calculations, the finite element method was used. Used specialized software package APM WinMachine. A computational experiment was conducted. A correlation analysis of the theoretical and actual structural model of the bearing is carried out. Results. Mathematical models of the metal structures of bearings of various sections are given and the locations of the highest stresses are identified. Calculation errors and correlation dependencies of stresses are established taking into account the Pearson, Fisher criteria and the construction of the Taylor series. Conclusions. The results of a computational experiment satisfy the requirements and can be used to solve further problems of designing bearing assemblies. In the future, a parameter-dependent model can be created that makes it easier to calculate using any type of bearing
10
He, Li, Yi Tang Zhou, Xi Zhong, and Jie Zhou. "Studies of the Optimal Hardening Parameters in Sandy Soil Shear Hardening Constitutive Model." Applied Mechanics and Materials 444-445 (October 2013): 1527–31. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.1527.
Повний текст джерелаАнотація:
Through a series of drainage analysis of plane strain compression tests on the Toyoura sand under different stress path, we found that the plastic shear strain and stress path of great relevance. But due to that a yield locus represents a specific yield level and usually do not related with stress paths, the hardening parameter of the parametric should also has nothing to do with the stress path. This article based on the analysis of the laboratory test results, put forward a stress path-independent plastic shear strain energy modified function as shear yield hardening parameters. Then based on the above type of energy state function proposed to build a sandy soil elasto-plastic constitutive model, and compared with corresponding numerical calculation results to make an effective verification.
11
Ermagan, Roya, Maxime Sauzay, Matthew H. Mecklenburg, and Michael E. Kassner. "Determination of Long-Range Internal Stresses in Cyclically Deformed Copper Single Crystals Using Convergent Beam Electron Diffraction." Crystals 10, no. 12 (November 24, 2020): 1071. http://dx.doi.org/10.3390/cryst10121071.
Повний текст джерелаАнотація:
Understanding long range internal stresses (LRIS) may be crucial for elucidating the basis of the Bauschinger effect, plastic deformation in fatigued metals, and plastic deformation in general. Few studies have evaluated LRIS using convergent beam electron diffraction (CBED) in cyclically deformed single crystals oriented in single slip and there are no such studies carried out on cyclically deformed single crystals in multiple slip. In our earlier and recent study, we assessed the LRIS in a cyclically deformed copper single crystal in multiple slip via measuring the maximum dislocation dipole heights. Nearly equal maximum dipole heights in the high dislocation density walls and low dislocation density channels suggested a uniform stress state across the labyrinth microstructure. Here, we evaluate the LRIS by determining the lattice parameter in the channels and walls of the labyrinth dislocation structure using CBED. Findings of this work show that lattice parameters obtained were almost equal near the walls and within the channels. Thus, a homogenous stress state within the heterogeneous dislocation microstructure is again suggested. Although the changes in the lattice parameter in the channels are minimal (less than 10−4 nm), CBED chi-squared analysis suggests that the difference between the lattice parameter values of the cyclically deformed and unstrained copper are slightly higher in the proximity of the walls in comparison with the channel interior. These values are less than 6.5% of the applied stress. It can be concluded that the dominant characteristics of the Bauschinger effect may need to include the Orowan-Sleeswyk mechanism type of explanation since both the maximum dipole height measurements and the lattice parameter assessment through CBED analysis suggest a homogenous stress state. This work complements our earlier work that determined LRIS based on dipole heights by assessing LRIS through a different methodology, carried out on a cyclically deformed copper single crystal oriented for multiple slip.
12
Singh, A. K., K. C. Mistri, and A. Das. "Propagation of Love-Type Wave in a Corrugated Fibre-Reinforced Layer." Journal of Mechanics 32, no. 6 (June 17, 2016): 693–708. http://dx.doi.org/10.1017/jmech.2016.40.
Повний текст джерелаАнотація:
AbstractThe present paper investigates the propagation of Love-type waves in an initially stressed heterogeneous fibre-reinforced layer with corrugated boundary surfaces, lying over a viscoelastic half-space under hydrostatic state of stress. The dispersion relation is obtained in closed form and found to be in well-agreement with the classical Love wave equation. The substantial effect of reinforcement, position and undulation parameters (i.e. corrugation), heterogeneity, horizontal initial stress and hydrostatic state of stress are discussed briefly. It is established through comparative study that reinforced layer supports more to phase velocity of Love-type wave as compare to reinforced free layer.
13
Verma, Amit K., Amares Chattopadhyay, Mriganka S. Chaki, and Abhishek K. Singh. "Dispersion of Rayleigh-Type Wave in an Exponentially Graded Incompressible Crustal Layer Resting on Yielding Foundation." Journal of Theoretical and Computational Acoustics 27, no. 03 (September 2019): 1850038. http://dx.doi.org/10.1142/s259172851850038x.
Повний текст джерелаАнотація:
The objective of this study is to develop a theory to study the propagation of Rayleigh-type waves in an inhomogeneous layer having yielding surface. A detailed study of a Rayleigh-type wave propagating in an exponentially graded incompressible layer resting on yielding surface is considered. The frequency equation being a function of phase velocity, wave number and heterogeneity parameter associated with the yielding parameter and density of inhomogeneous layer reveals the fact that Rayleigh-type wave propagation is greatly influenced by the above-stated parameters. In particular cases, the dispersion relation has been discussed for stress-free foundation by taking yielding parameter tending to zero. In numerical and graphical computation, the significant effects of distortional velocity have been carried out. Moreover, the obtained dispersion relation is found in well agreement to the classical case in homogeneous isotropic layer resting on a yielding foundation.
14
Dagwal, V. J., D. D. Pawar, and Y. S. Solanke. "Study of cosmic models in f(R,T) gravity with tilted observers." Modern Physics Letters A 35, no. 38 (November 3, 2020): 2050316. http://dx.doi.org/10.1142/s0217732320503162.
Повний текст джерелаАнотація:
In this work, we have studied LRS Bianchi type I cosmological models in [Formula: see text] gravity with tilted observers, where [Formula: see text] is the Ricci scalar and [Formula: see text] is the trace of the stress energy tensor. We have explored a tilted model and determined the solutions of the field equations by assuming special law of variation of Hubble’s parameter, proposed by Berman (1983) that yields constant deceleration parameter. In this scenario, we have used the equation of state [Formula: see text] and power law of velocity to describe the different anisotropic physical models such as Dust Universe, Radiation Universe, Hard Universe and Zedovich Universe. We have discussed graphical presentation of all parameters of the derived models with the help of MATLAB. Some physical and geometrical aspects of the models are also discussed.
15
Yi, You Ping, Hua Chen, and Yong Cheng Lin. "Investigation of Flow Stress Behavior and Microstructural Evolution of 7050 Al Alloy." Materials Science Forum 546-549 (May 2007): 1065–68. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.1065.
Повний текст джерелаАнотація:
The plastic deformation behaviors of 7050 Al alloy were investigated by compression tests at temperatures ranging of 250°C450°C under constant strain rates of 0.01s−1, 1s−1 and 10s−1. The results showed that all the flow curves consisted of three stages, i.e. strain-hardening, strain-softening and steady state-strain. Initially, the stress rises steeply at microstrain deformation, and then increases at a decreased rate, followed by a strain-softening until a steady state stress. The stress level decreases with increasing deformation temperature and decreasing strain rate, which can be represented by a Zener-Hollomon parameter in an exponent-type equation, 1 19 7.202 σ p 80.71 sinh (1.64 10 Z) = ⋅ − × − ⋅ − . Elongated grains with serrations developed in the grain boundaries were observed; the dynamic recrystallization (DRX) occurs with increasing temperature and dislocation density, and the shape of grain at steady state is nearly equiaxial. It can be concluded that the DRX phenomenon is sensitive to the temperature and the dynamic flow softening is mainly as the result of dynamic recovery and DRX.
16
Reznik, V. S. "Justification of application of nonlinear viscoelasticity model of Rabotnov's model type in creep problems." Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, no. 3 (2021): 111–14. http://dx.doi.org/10.17721/1812-5409.2021/3.21.
Повний текст джерелаАнотація:
The relationship between the components of the strain tensor, stress tensor and time is given by the defining equations of the hereditary type, which are written based on the hypothesis of proportionality of the deviators. Thin-walled tubular low-pressure polyethylene elements are considered as the object of research. The scope of the model is substantiated based on the hypothesis of the existence of a single diagram of instantaneous deformation and a single diagram of long-term deformation. The invariance of the tensile and torsion diagrams with respect to the stress state is checked. The region of nonlinear elastic deformation is determined. The defining equations of the model contain a set of functions and coefficients determined from the basic experiments. A method for determining the parameters of heredity kernels of nonlinear viscoelastic materials under complex stress state has been developed. The nonlinearity of viscoelastic properties is given by equations of the Rabotnov's model type. The method is based on the relations between the creep kernels obtained under conditions of complex stress state and the creep kernels under one-dimensional stress state. The method is tested experimentally on the problems of calculating creep deformations under combined loading of thin-walled tubular elements made of low-pressure polyethylene.
17
Reznik, V. S. "On some method of the heredity kernel parameters determination of nonlinear viscoelastic materials under the complex stress state." Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, no. 1 (2019): 178–81. http://dx.doi.org/10.17721/1812-5409.2019/1.41.
Повний текст джерелаАнотація:
The deformation of viscoelastic medium given by means of constitutive equations of the hereditary type. These equations establish the relationship between the components of strain tensor, the components of stress tensor and the integral time operator, and contain the set of function and coefficients that are determined from the basic experiments. А method of the heredity kernel parameters determination of nonlinear viscoelastic materials is developed. As the visco-elastic model, the constitutive equations of the hereditary type are chosen in which the relationship between the components of the strain tensor and the stress tensor is given based on the hypothesis of the deviators proportionality. The nonlinearity of the viscoelastic properties is given by the equations of Ratotnov’s type. The method is based on the relations between the creep kernels under complex stress state and the creep kernels under one-dimensional stress state. The method verified experimentally for the problems of determination of creep deformations under combined loading applied to the thin-walled tubular elements made of polyethylene of high density.
18
Deswal, Sunita, Sandeep Singh Sheoran, and Kapil Kumar Kalkal. "The Effect of Magnetic Field and Initial Stress on Fractional Order Generalized Thermoelastic Half-Space." Journal of Mathematics 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/489863.
Повний текст джерелаАнотація:
The aim of this paper is to study magneto-thermoelastic interactions in an initially stressed isotropic homogeneous half-space in the context of fractional order theory of generalized thermoelasticity. State space formulation with the Laplace transform technique is used to obtain the general solution, and the resulting formulation is applied to the ramp type increase in thermal load and zero stress. Solutions of the problem in the physical domain are obtained by using a numerical method of the Laplace inverse transform based on the Fourier expansion technique, and the expressions for the displacement, temperature, and stress inside the half-space are obtained. Numerical computations are carried out for a particular material for illustrating the results. Results obtained for the field variables are displayed graphically. Some comparisons have been shown in figures to present the effect of fractional parameter, ramp parameter, magnetic field, and initial stress on the field variables. Some particular cases of special interest have been deduced from the present investigation.
19
Pavanello, Paolo, Paolo Carrubba, and Nicola Moraci. "Geosynthetic Interface Friction at Low Normal Stress: Two Approaches with Increasing Shear Loading." Applied Sciences 12, no. 3 (January 20, 2022): 1065. http://dx.doi.org/10.3390/app12031065.
Повний текст джерелаАнотація:
The evaluation of geosynthetic interface friction is a key parameter for the stability of coupled geosynthetics, as in landfill capping liner. At the present time, few types of tests are suitable for measuring the interface friction at low normal stress: one of these is the inclined plane, usually carried out under a vertical stress of 5 kPa. This type of test is not without critical aspects, mainly due to the nonuniform normal stress state induced by the inclination of the plane, but, on the other hand, the most widespread direct shear test generally cannot be performed at such low values of normal stress. After a short discussion on the pros and cons of these two types of test, the paper presents a comparison of the interface friction angles obtained, for three interfaces, by means of an inclined plane and an unconventional direct shear apparatus, under the same low normal stress. The peculiarity of this latter device is of ensuring a gradual increase of the mobilized strength, in a way similar to what occurs during the inclined plane test. The good correspondence of the results of the two types of tests confirmed the validity of both the test approaches.
20
Kadivar, Mehdi, Kalehiwot Nega Manahiloh, and Victor N. Kaliakin. "Examining the predictive capabilities of a bounding surface plasticity-based hyperelastic constitutive model for unsaturated granular soils." MATEC Web of Conferences 337 (2021): 02005. http://dx.doi.org/10.1051/matecconf/202133702005.
Повний текст джерелаАнотація:
The performance of a recently developed state-dependent constitutive model for unsaturated granular soils is evaluated. The model employs the Bounding Surface plasticity framework and evaluates elastic strains assuming hyperelastic behavior. To realistically simulate the deformation of unsaturated granular soils, the mechanical behavior was modeled without a purely elastic component. The inherent hydro-mechanical coupling was realized by introducing a Bishop-type effective stress, an appropriate work-conjugate variable, and a soil-water characteristic curve function. Relevant details about the model development, parameter estimation, and the assessment of the model’s predictive capabilities are presented. The model performance is evaluated with experimental data obtained for drained and constant-water stress paths. With a given a set of parameter values, the model realistically simulates the main features that characterize the shear and volumetric behavior of unsaturated granular soils over a wide range of matric suction, density, and net confining pressure. This is found to be true for both drained and constant-water stress paths.
21
Hopmann, Ch, and C. Zimmermann. "Characterisation of the quasi-static material behaviour of thermoplastic elastomers (TPE) under consideration of temperature and stress state." Journal of Elastomers & Plastics 52, no. 3 (March 21, 2019): 199–215. http://dx.doi.org/10.1177/0095244319835868.
Повний текст джерелаАнотація:
This article deals with the determination of the mechanical material behaviour of injection-moulded thermoplastic elastomers (TPE). For this purpose, the mechanical behaviour of TPE is investigated on basis of different materials (type and hardness) and process parameters with regard to the process-induced anisotropy. Based on these investigations, an almost isotropic material was selected for the investigations about the influence of temperature, stress state and load level. The results confirm that the hardness of the material and type of the processed material have an impact on the mechanical properties longitudinal and transversal to the flow direction. Furthermore, TPE behave quite similar to pure elastomers, as they showed a non-linear material behaviour, a stress softening after initial loading and a residual deformation after unloading. All these effects also depend on the temperature, stress state and load level, which results in a complex material behaviour. At the end of the article, two calibration approaches of a hyperelastic material model were shown (one set of parameters for all stress states vs. one set of parameters for each stress state). The second approach (one set of parameters for each stress state) shows a much higher accuracy in approximation of the test results.
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Pala, Robert, Jarosław Galkiewicz, and Ihor Dzioba. "Experimental and Numerical Modeling of the Phenomenon of Delamination Cracking in S235 Steel." Solid State Phenomena 250 (April 2016): 145–50. http://dx.doi.org/10.4028/www.scientific.net/ssp.250.145.
Повний текст джерелаАнотація:
In the paper was compared the stress state in front of the crack for SEN(B) specimens of S235RJ steel without and with delamination cracks. Stress distribution and characteristics of stress state triaxiality were calculated for both type of specimens. It was showed a reduction in the stress fields and triaxiality parameters in front of the main crack in the presence of delamination cracking.
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Singh, AK, KC Mistri, and A. Chattopadhyay. "Normal load moving on magneto-elastic transversely isotropic half-space with irregular and hydrostatic initial stress." Journal of Vibration and Control 23, no. 8 (July 14, 2015): 1354–73. http://dx.doi.org/10.1177/1077546315593001.
Повний текст джерелаАнотація:
The present paper investigates the effect of initial stress, irregularity depth, irregularity factor and magneto-elastic coupling parameter on the dynamic response due to a normal moving load with constant velocity on the free surface of an irregular magneto-elastic transversely isotropic half-space under the state of hydrostatic initial stress. The expressions for normal stress and shear stress are obtained in closed form analytically. The considerable effect of initial stress, irregularity depth, irregularity factor and magneto-elastic coupling parameter on normal stress and shear stress are computed numerically and depicted by means of graphs. Moreover, comparative study highlighting the effect of various types of irregularity viz. rectangular irregularity, parabolic irregularity and no irregularity on the normal stress and shear stress is a key feature of the study.
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Zhang, Li Wen, Ru Cheng Xiao, and Rui Jie Xia. "Mechanical Analysis and Study on Structural Parameter of Partially Earth-Anchored Cable-Stayed Bridge Part I: Mechanical Analysis." Applied Mechanics and Materials 44-47 (December 2010): 1898–905. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.1898.
Повний текст джерелаАнотація:
Based on a partially earth-anchored cable-stayed bridge with 1218m main span and composite beam, the mechanical analysis of this bridge type was conducted in this paper. The bridge was simulated with space pole department model, in which the beam element was used to model girder and tower, the truss element was used to model stayed-cable whose sag effect was corrected by Ernst theory. The load cases considered in analysis include: the completion state, the live load, the temperature load and other load combination. The analysis content include: the structural deformation, the structural internal force, the structural stress.
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Smirnov, V. B., A. V. Ponomarev, S. A. Stanchits, M. G. Potanina, A. V. Patonin, G. Dresen, C. Narteau, P. Bernard, and S. M. Stroganova. "Dependences of the Omori and Gutenberg–Richter parameters." Физика Земли, no. 1 (March 27, 2019): 149–65. http://dx.doi.org/10.31857/s0002-333720191149-165.
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Laboratory experiments on studying the aftershock regime are carried out with sandstone specimens under different axial loading and uniform compression and constant pore pressure. The aftershock sequences are modeled by the scenario of stepwise increasing axial loading of a specimen with strain control ensuring regular generation of aftershock sequences. The experiments are conducted on intact specimens and on the specimens with preliminarily formed shear macrofractures simulating natural faults. The experiments were conducted with multichannel recording of the acoustic emission (AE) signals which made it possible to locate the AE sources. Several types of the dependence of the acoustic activity relaxation parameters (parameters p and c of the modified Omori law and the Gutenberg–Richter b-value) on the level of acting stresses are revealed. The b-value decreases with the growth of axial stresses at all levels of uniform compression. In the case of fracture on the preexisting fault, the Omori relaxation parameter p increases with the growth of axial stresses whereas parameter c (the time delay before the onset of relaxation) decreases with the growth of axial stresses and increases with the rise of the level of uniform compression. In the case of a fracture of an undamaged specimen, parameter p remains unchanged as the axial stresses grow, whereas parameter c increases slightly. Parameter variations in the case of a complex stress state with both varying deviatoric (differential stresses) and spherical parts (effective pressure) of the stress tensor take on a unified form when expressed in terms of Coulomb stresses. It is hypothesized that the time delay of the aftershock activity relaxation is determined by the kinetics of fracture in accordance with the kinetic concept of strength in solids. This hypothesis is supported by exponential dependence of parameter c on stresses and on the effective strength of the medium revealed in the experiments. Under this hypothesis, the dependences of parameter c on the Coulomb stresses can be unified for different effective strength values with the use of Zhurkov’s formula for durability of materials. The obtained parameter estimates for the dependence of c on strength and stresses suggest that the c value is determined by the difference of the strength and the acting stresses, indicating how far the stress state of the medium is from the critical state corresponding to the ultimate strength.
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Sah, Injin, Jong-Bae Hwang, and Eung-Seon Kim. "Creep Behavior of Diffusion-Welded Alloy 617." Metals 11, no. 5 (May 19, 2021): 830. http://dx.doi.org/10.3390/met11050830.
Повний текст джерелаАнотація:
Plate-type heat exchangers are anticipated to be used in the next-generation nuclear industry, and solid-state diffusion welding is a critical technology for building plate-type heat exchangers with high integrity. In this study, we manufactured a diffusion weldment and evaluated its creep behavior. Microscopic analysis revealed that Al-rich oxides were developed along the interface, significantly impeding grain-boundary movement across the interface. Oxide-containing planar grain boundaries resulted in premature brittle fracture at the interface with less than 9% creep strain under all test conditions. The time to rupture and time to 1% creep strain of the diffusion weldment were less than those of the as-received alloy, while the slopes in double-logarithmic plots were almost identical for both alloys. In a Larson–Miller parameter study, the stress to rupture of the diffusion weldment reached 95.59% of that of the as-received alloy, whereas the stress to 1% creep strain steeply decreased in the low-stress range.
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Deswal, Sunita, and Kapil Kumar Kalkal. "Two Temperature Magneto-Thermoelasticity with Initial Stress: State Space Formulation." Journal of Thermodynamics 2013 (September 30, 2013): 1–12. http://dx.doi.org/10.1155/2013/754798.
Повний текст джерелаАнотація:
Magneto-thermoelastic interactions in an initially stressed isotropic homogeneous elastic half-space with two temperatures are studied using mathematical methods under the purview of the L-S model of linear theory of generalized thermoelasticity. The formalism deals with the state space approach with the purpose of counteracting the difficulties of handling the displacement potential functions. Of specific concern here is the propagation of waves owing to ramp type increase in temperature and load. The medium is considered to be permeated by a uniform magnetic field. The expressions for different field parameters such as displacement, temperature, strain, and stress in the physical domain are obtained by applying a numerical inversion technique. Results of some earlier workers have been deduced from the present formulation. Numerical work is also performed for a suitable material with the aim of illustrating the results.
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Shi, Junping, Xiaoshan Cao, and Chao Shen. "Damage Criteria Based on Plastic Strain Energy Intensity Under Complicated Stress State." International Journal of Applied Mechanics 07, no. 06 (December 2015): 1550089. http://dx.doi.org/10.1142/s1758825115500891.
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In this study, total strain theory and isotropic hardening model based on Mises yield condition are used to derive the expression for plastic strain energy density under complicated stress state. The normal and shear stress distributions of a solid cylindrical bar under a combination of tensile and torsional stresses as well as the equation and integral formula for plastic strain energy density are presented. The plastic strain energy density of critical point and the plastic strain energy intensity on the fracture plane of different materials under several typical stress states are obtained by measuring the fracture data of different materials. With the plastic strain energy intensity as the failure parameter, uniaxial tensile experiments were conducted to measure the final plastic strain energy intensity of the failure section. The plastic strain energy intensity failure criteria of the material under complex stress state are established. Combined tension–torsion tests were conducted on two types of materials, LC9 and LY12, to verify the validity and applicability of the criteria.
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Qian, Pingping, Zhenghua Tang, Li Wang, and Charles W. Siyasiya. "Hot Deformation Characteristics and 3-D Processing Map of a High-Titanium Nb-Micro-alloyed Steel." Materials 13, no. 7 (March 25, 2020): 1501. http://dx.doi.org/10.3390/ma13071501.
Повний текст джерелаАнотація:
Hot deformation behavior of a high-titanium Nb-micro-alloyed steel was investigated by conducting hot compression tests at the temperature of 900–1100 °C and the strain rate of 0.005–10 s−1. Using a sinh type constitutive equation, the apparent activation energy of the examined steel was 373.16 kJ/mol and the stress exponent was 6.059. The relations between Zener–Hollomon parameters versus peak stress (strain) or steady-state stress (strain) were successfully established via the Avrami equation. The dynamic recrystallization kinetics model of the examined steel was constructed and the validity was confirmed based on the experimental results. The 3-D atomic distribution maps illustrated that strain can significantly affect the values of power dissipation efficiency and the area of instability domains. The 3-D processing maps based on a dynamic material model at the strains of 0.2, 0.4, 0.6 and 0.8 were established. Based on traditional and 3-D processing maps and microstructural evaluation, the optimum parameter of for a high-titanium Nb-micro-alloyed steel was determined to be 1000–1050 °C/0.1–1 s−1.
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Astefanoaei, Iordana, Ioan Dumitru, and Alexandru Stancu. "Laser Heating of the Core-Shell Nanowires." Annals of West University of Timisoara - Physics 59, no. 1 (December 1, 2016): 2–12. http://dx.doi.org/10.1515/awutp-2016-0002.
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AbstractThe induced thermal stress in a heating process is an important parameter to be known and controlled in the magnetization process of core-shell nanowires. This paper analyses the stress produced by a laser heating source placed at one end of a core-shell type structure. The thermal field was computed with the non-Fourier heat transport equation using a finite element method (FEM) implemented in Comsol Multiphysics. The internal stresses are essentially due to thermal gradients and different expansion characteristics of core and shell materials. The stress values were computed using the thermo elastic formalism and are depending on the laser beam parameters (spot size, power etc.) and system characteristics (dimensions, thermal characteristics). Stresses in the GPa range were estimated and consequently we find that the magnetic state of the system can be influenced significantly. A shell material as the glass which is a good thermal insulator induces in the magnetic core, the smaller stresses and consequently the smaller magnetoelastic energy. These results lead to a better understanding of the switching process in the magnetic materials.
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Branco, R., J. M. Silva, V. Infante, F. Antunes, and F. Ferreira. "Using a standard specimen for crack propagation under plain strain conditions." International Journal of Structural Integrity 1, no. 4 (November 1, 2010): 332–43. http://dx.doi.org/10.1108/17579861011099169.
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PurposeStress state has a major influence on different phenomena, namely those involving diffusion and plastic deformation (like crack closure and high‐temperature fatigue crack growth, void formation or ductile fracture). The isolation of plane stress and plane strain states is crucial in fundamental studies of material behavior. The isolation of plane stress state is achieved with thin specimens, whilst the isolation of plane strain state is usually done increasing the thickness or introducing lateral grooves. The purpose of this paper is to propose a specimen geometry able to isolate the plane strain state, based on the standard M(T) geometry.Design/methodology/approachA numerical study was carried out aiming at obtaining a stress triaxiality parameter, h, as a function of different geometrical features of the specimen, such as the notch radius, notch depth and specimen thickness.FindingsResults show that a pure plane strain state is achievable (i.e. 97 percent of specimen thickness has h>0.97) if a specimen with optimized geometrical features is used, which corresponds to a notch radius of 0.5 mm, a notch depth of 1 mm and a total specimen thickness of 12.56 mm.Originality/valueThis type of specimen geometry is a simple and efficient alternative to other common approaches used to obtain pure plain strain conditions for experimental purposes.
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Ha, Jinjin, and Yannis P. Korkolis. "Hole-Expansion: Sensitivity of Failure Prediction on Plastic Anisotropy Modeling." Journal of Manufacturing and Materials Processing 5, no. 2 (March 25, 2021): 28. http://dx.doi.org/10.3390/jmmp5020028.
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The influence of yield function parameters on hole-expansion (HE) predictions are investigated for an anisotropic AA6022-T4 aluminum sheet. The HE experiment is performed in a fully-instrumented double-action hydraulic press with a flat-headed punch. Full strain fields are measured by a stereo-type digital image correlation (DIC) system. The stress state gradually changes from uniaxial to plane-strain tension to biaxial tension in the radial direction. Besides HE, the plastic anisotropy of AA6022-T4 is characterized by uniaxial tension and plane-strain tension experiments. Uniaxial tension is considered as the most important, since it is the stress state along the hoop direction in the hole. For the finite element (FE) simulation, the Yld2000-2d non-quadratic anisotropic yield function is used with two different parameter sets, calibrated by: (1) uniaxial tension only (termed Calib1) and, (2) both uniaxial and plane-strain tension (Calib2). The strain field predictions show a good agreement with the experiments only for Calib2, which takes into account plane-strain as well uniaxial tension. This indicates the importance of biaxial modes, and in particular plane-strain tension, for the adopted yield function to produce accurate HE simulations.
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Brøns, Morten. "Relaxation oscillations and canards in a nonlinear model of discontinuous plastic deformation in metals at very low temperatures." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 461, no. 2059 (June 16, 2005): 2289–302. http://dx.doi.org/10.1098/rspa.2005.1486.
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For metals in tensile tests, discontinuous plastic deformation is a state where the stress oscillates rather than obtaining a stationary level. Estrin & Kubin have proposed a simple nonlinear model, valid in the cryogenic range, which contains a Hopf bifurcation, indicating the onset of discontinuous plastic deformation. We analyse the model for post-bifurcation behaviour and identify three parameter ranges with different transitions to relaxation oscillations (associated with the singular perturbation nature of the model). In one range, the transition is of the explosive canard type, where amplitude and period change dramatically over a very short parameter range. We derive general asymptotic formulae for the canard point and obtain excellent agreement with numerical simulations.
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Stepanova, L. V. "Asymptotic stress fields in the vicinity of the crack in perfectly plastic solids under mixed mode loading." PNRPU Mechanics Bulletin, no. 3 (December 15, 2020): 73–89. http://dx.doi.org/10.15593/perm.mech/2020.3.08.
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In the paper presents the asymptotic stress fields in the vicinity of the crack tip in perfectly plastic Mises materials under mixed mode loading for a full range of the mode mixities. This objective is engendered by the necessity of considering all the values of the mixity parameter for the full range of the mode mixities both for plane strain and plane stress conditions to grasp stress tensor components behaviour in the vicinity of the crack tip as the mixity parameter is changing from 0 to 1. To gain a better understanding of the stress distributions, all values of the mixity parameter within 0.1 were considered and analyzed. The asymptotic solution to the statically determinate problem is obtained using the eigenfunction expansion method. Steady - state stress distributions for the full range of the mode mixities are found. The type of the mixed mode loading is controlled by the mixity parameter changing from zero for pure mode II loading to 1 for pure mode I loading. It is shown that the analytical solution is described by different relations in different sectors, the value of which is changing from 7 sectors to 5 sectors. At loadings close to pure mode II, seven sectors determine the solution whereas six and five sectors define the solution for the mixity parameter higher 0.33 and less than 0.89 and higher 0.89 respectively for plane strain conditions and seven sectors determine the asymptotic solution for the mixity parameter less than 0.39, while five sectors determine the solution for other values of the mixity parameter for plane stress conditions. The number of sectors depends on the mixity parameter. The angular stress distributions are not fully continuous and radial stresses are discontinuous for some values of the mixity parameter. It is interesting to note that the characteristic feature of the asymptotic solution obtained is the presence of a segment of values of the mixity parameter for which the solution does not depend on the mixity parameter (the solution does not depend on the mixity parameter for the mixity parameter from 0.89 to 1 and the solution coincides with the solution for mode I crack in perfect plastic materials for plane strain conditions). Thus, the salient point of the study is that the asymptotic solution is described by the same formulae for all values of the mixity parameter from 0.89 to 1 for plane strain. For plane stress conditions this segment can’t be observed. The solution in each sector corresponds to the certain value of the mixity parameter. The obtained solutions for plane strain and plane stress conditions can be considered as the limit solution for power law hardening materials and creeping power law materials.
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Tsvik, L. B., and E. V. Zenkov. "A comparative analysis of the stress-strain state of disc specimens in assessing the structural strength of materials." Engineering Solid Mechanics 10, no. 1 (2022): 25–34. http://dx.doi.org/10.5267/j.esm.2021.12.001.
Повний текст джерелаАнотація:
A study of the stress-strain state (SSS) of disc specimens has been conducted when testing specimens with stress concentrators (grooves). The research has shown that the truncation of circular discs along two symmetrical chords makes it possible to change the type (the ratio of principal stresses) of SSS that occurs at the destruction site. Therefore, these specimens can be used to assess the structural strength of materials on standard single-drive testing machines, taking into account the real type of SSS that occurs in the bearing elements of machines. The results of numerical SSS modeling have been used to build the dependences of the SSS type and level on geometric parameters of specimens. Geometrical parameters can be chosen for a certain SSS type to assess both the static and fatigue strengths of materials used in the manufacture of bearing elements.
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Kuzmov, A., M. Shtern, and P. Korobko. "Modeling of influence of planar defects on plasticity of powder materials by computational methods of micromechanics." Uspihi materialoznavstva 2021, no. 3 (December 1, 2021): 77–85. http://dx.doi.org/10.15407/materials2021.03.077.
Повний текст джерелаАнотація:
Based on the energy concept of the critic stress state, a three-parameter model of plasticity of the Cam-Clay type was formulated. For this phenomenological model, the dependences of the determining parameters on the porosity and damage were found by the method of micromechanical averaging on the unit cell corresponding to the porous damaged material of powder origin. The plastic multi-responce (different yield strength in tension and compression) behavior of this material is found by micromechanical averaging on a unit cell. According to the mechanics of composites, the geometry of the cell represents the structure of a heterogeneous material and the boundary conditions on a unit cell make it possible to relate the stress-strain state at the macro- and meso-level. The averaging was carried out by computer simulation using the finite element method with an adaptive mesh, which was automatically condensed in places of a large gradient of the stress-strain state. The structure of the representative cell corresponds to a powder origin material with "imperfect", partially stratified, interparticle contacts. In the proposed model the rheological response of a porous damaged material is specified by three moduli, and the structure of such a material is described by two internal state parameters: porosity and the degree of delamination of interparticle contacts. That is, the rheological moduli are functions of porosity and damage. Accordingly, a number of values of each of the moduli were calculated for a certain discrete range of density and damage. The advantage of this approach is precisely in focusing on powder origin materials and not generally on any damaged materials, which makes it possible to take into account the real structure of the damaged material using the methods of mechanics of microheterogeneous materials. According to the simulation results, in particular, it was found that the yield strength for shear is significantly (30%) less sensitive to damage than the yield strength for uniaxial tension. Keywords: theory of plasticity, powder materials, micromechanics, damaged materials, stress-strain state.
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Grushko, A. V. "Phenomenological approach to the determination of the stress state of the indicator chart for plasticity." Izvestiya MGTU MAMI 7, no. 2-2 (March 20, 2013): 149–53. http://dx.doi.org/10.17816/2074-0530-68146.
Повний текст джерелаАнотація:
We propose a parameter state of stress as the sum of the principal stresses relative to the odds of their influence. Influence coefficients are mechanically-mi material properties. Plasticity chart with this indicator is proposed to approximate the exponential function. Checking for different materials showed sufficient proximity of the experimental points to a diagram of plasticity. Recommendations are given for determining the coefficients of arbitrary types of tests. The minimum number of tests - 4.
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Sanju Nanda and Mohini Bajaj. "Solution state stress degradation studies of antifilarial drug albendazole." International Journal of Research in Pharmaceutical Sciences 10, no. 4 (December 3, 2019): 3738–49. http://dx.doi.org/10.26452/ijrps.v10i4.1763.
Повний текст джерелаАнотація:
This study was conducted to explore the stress degradation studies of antifilarial drug albendazole (ALB) in the solution state. The stress conditions targeted were hydrolytic (acidic, neutral, and basic) as well as oxidative. The drug was degraded under different concentrations of stressor and time of exposure. All the degraded samples were then subjected to reversed-phase high-performance liquid chromatography using photodiode array (HPLC-PDA) as a detector. The final concentration of stressor, as well as the duration of exposure for each condition, were optimized from the results. The method optimization was also done on a C18 stationary phase with a varying mobile phase composition. The parameters of the mobile phase varied were organic modifier and buffer type and concentration and gradient as well as run time. The optimized method included acetonitrile as an organic modifier, 10 mM potassium dihydrogen orthophosphate buffer (pH 3.0) as a buffer that was pumped in a gradient mode, and run time was fixed at 57.00 min. The samples were further characterized by subjecting to instrumental technique Liquid Chromatography High-Resolution Mass Spectrometry (LC-HRMS). The results highlighted the degradation products formed under the study conditions. Some of the degradation products were common to all hydrolytic conditions, but some were seen only under oxidative conditions.
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Luo, Yuhu, Bo Tian, and Kaimin Niu. "Numerical Analysis of Reflective Cracking of Continuous Reinforced Composite Pavement under Multifactor Coupling." Mobile Information Systems 2021 (October 18, 2021): 1–18. http://dx.doi.org/10.1155/2021/7065124.
Повний текст джерелаАнотація:
The occurrence and expansion of reflective cracking is a typical problem associated with the composite pavement that has a proven impact on the life of the continuous reinforced composite pavement. The current research studies a 3D finite element model to preset cracks at the top of the continuously reinforced concrete (CRC) layer’s transverse crack and at the bottom of the asphalt concrete (AC) layer based on the theory of linear elastic fracture mechanics in order to explore the factors responsible for the reflective cracking formation mechanism and expansion law. Considering the main stress parameters that affect the formation of reflective cracking (layer bottom tensile stress and vertical shear stress), the most unfavorable load position and the most unfavorable point of the corresponding stress parameter are determined that are then used to calculate the stress intensity factor of the crack tip under the coupling effect of multiple factors based upon the position and point above the crack, by using the confinement integral. The variance analysis of the stress intensity factor of the crack tip under the multifactor coupling effect is conducted via an orthogonal test in order to determine the main factors affecting the formation and development of reflective cracking. Meanwhile, the analysis of single-factor sensitivity is carried out on all these factors, which reveal the real contribution in the formation and expansion of reflective cracking in the continuous reinforced composite pavement. The results show that the most unfavorable load position for reflective cracking is when the load is on the side of the CRC layer’s lateral crack, while the most unfavorable point of the stress parameter is concentrated within the range of the wheel track. At the same time, analysis of multifactor variance and that of single-factor sensitivity show that the cracking mode of reflective cracking in the continuous reinforced composite pavement is a mixed one, dominated by K2 (slip type), supplemented by K1 (open type), and participated by K3 (tear type), whereas the AC layer’s preset-crack depth ratio, instantaneous temperature drop, and CRC-transverse-crack load transfer capacity are the main factors that affect the formation and development of the reflective cracking. Moreover, a better bonding state between the AC layer and the CRC layer improves the stress intensity factor of the preset crack tip on the bottom of the AC layer.
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Romanov, A. V., and P. V. Fernati. "To the problem of influence of the third invariant of stress deviator on the process of longterm deformation of nonlinear viscoelastic materials." Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, no. 1 (2019): 186–89. http://dx.doi.org/10.17721/1812-5409.2019/1.43.
Повний текст джерелаАнотація:
The problem on the influence of stressed state on the process of long-term deformation of nonlinear viscoelastic materials under the simple and quasi-simple modes of loading by introduction of the function with the parameter of Lode angle into the defining equations is considered. The mentioned function is determined by analysis of base experimental data obtained from the base experiments on axial tension and pure torsion. Physical and mechanical properties of nonlinear viscoelastic solids are defined by the correspondence between the invariants of deformation tensors and tensions according to the modified nonlinear Rabotnov’s model for viscoelasticity. The heredity kernels are given by the fractional-exponential function. The constructed defining equations are verified experimentally for the problems of determination of nonlinear creep deformations under combined loading applied to the thin-walled tubular elements made of polyethylene of high density and low pressure polyethylene. As a result of juxtaposition of experimental data and calculations it is a stated that allowing for the type of stressed state improves their agreement qualitatively and quantitatively.
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Bozhinskiy, A. N. "The Monte Carlo simulation of avalanche-type processes." Annals of Glaciology 38 (2004): 351–56. http://dx.doi.org/10.3189/172756404781814915.
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AbstractThe statistical modelling of gravitational avalanche-type processes is carried out using the Monte Carlo method. The process of snow avalanche origin is described with the model of stress state and stability of snow cover on a slope. The statistical simulation of the stress state of a snow slab is performed for avalanche site No. 22 (Khibiny, Russia). The strength characteristics of the snow slab are considered as randomvariables.The influence of the first moments of the distributions of the slab-strength parameters on the probability of avalanche release is studied. Using a hydraulic model of a dense flow avalanche, the statistical modelling of avalanche dynamics for the avalanche site “Domestic” (Elbrus region, Russia) is carried out. The coefficients of dry and turbulent friction and snow entrainment are considered as random parameters of the model. The histograms and distribution functions of the run-out distance, thickness and volume of avalanche depositions are obtained. The model and empirical distribution functions of the avalanche run-out distance are compared. Statistical simulation of slushflow dynamics (basin of Bear brook, Khibiny, Russia) is performed. The two-layer deterministic model of slushflow is used. The random parameters of the model assumed are: the water inflow on the “tail”of the flow and the coefficient of dry friction for slush. The histograms and distribution functions of dynamic characteristics of flow are obtained. The model outcomes are compared with field data.
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Tovstik, P. E. "ON THE FORMS OF LOCAL BUCKLING OF THIN ELASTIC SHELLS." Transactions of the Canadian Society for Mechanical Engineering 15, no. 3 (September 1991): 199–211. http://dx.doi.org/10.1139/tcsme-1991-0012.
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The stability of the membranous initial stress-strain state of equilibrium of thin elastic shells is studied. Using the two-dimensional theory of the Kirchhof-Love type, the linear problem of equilibrium bifurcation is considered. Buckling forms, localized near some lines or points on the middle surface of shell, called the weakest lines or points are studied. The asymptotic integration methods for equations with a parameter developed by A.L. Goldenveiser and V.P. Maslov are used. Approximate formulas for critical loads buckling forms which decrease with the deviation from the weakest line or point are found.
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Kowalska, Magdalena. "Influence of Loading History and Boundary Conditions on Parameters of Soil Constitutive Models." Studia Geotechnica et Mechanica 34, no. 1 (March 1, 2012): 15–33. http://dx.doi.org/10.1515/sgem-2017-0020.
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Abstract Parameters of soil constitutive models are not constant. This mainly concerns the strain parameters such as K, G or Eoed modules. What influences their values is not only soil type, structure and consistency, but also the history of stress and strain states. So, it is the question of the current state but also of what happened to the subsoil in the past (regarding geological and anthropological activity) and what impact would have the planned soil–structure interaction. This paper presents an overview of the literature showing how much the soil constitutive model parameters depend on loading and boundary conditions of a particular geotechnical problem. Model calibration methods are shortly described with special attention paid to the author’s “Loading Path Method”, which allows estimation of optimum parameter values of any soil constitutive model. An example of the use of this method to estimate strain parameters E and ν of Coulomb–Mohr elasticperfectly plastic model is given.
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Chizhik, S. A., M. A. Zhuravkov, A. B. Petrovskiy, V. Ya Prushak, and D. A. Puzanov. "Ultimate state criteria and strength characteristics of the rock massifs being undermined repeatedly." Proceedings of the National Academy of Sciences of Belarus, Physical-Technical Series 66, no. 4 (December 26, 2021): 420–29. http://dx.doi.org/10.29235/1561-8358-2021-66-4-420-429.
Повний текст джерелаАнотація:
Methodological approaches to the selection of ultimate state criteria and strength characteristics of the repeatedly undermined rock massifs were developed. These approaches were designed to provide parametric support to the geomechanical modelling of the massif stress-strain state and the mining systems of the Starobin potash deposit mine fields planned for the additional mining of the mineral reserves left. It was established that a complex criterion must be used to study the massif ultimate state. Determination of such criterion can be carried out using the developed approaches. The first approach is to select several criteria that evaluate the massif ultimate state by certain types of the massif stress-strain state. These criteria are the following: the criterion of the maximum normal stresses, criterion of the maximum linear strains, the criterion of the maximum shear stresses and the Coulomb–Mohr failure criterion. The second approach is to construct an integrated failure state criterion for materials whose ultimate tensile and compressive stresses differ significantly. In this case, parameters characterizing the type of stress state and properties of the material are introduced. These parameters together determine the destruction character – tear or shear. To describe the rocks behavior in the extreme strength stage of deformation, it is proposed to apply deformation theory of strength using the developed strain failure criterion. When calculating the strength characteristics of the repeatedly undermined rock massif, it is recommended to use a structural attenuation coefficient as the product of several factors, taking into account various types of disturbances in the primary undermined massif and the time factor. The Coulomb–Mohr strength condition is recommended to be used taking into account the composite structural attenuation coefficient. Dependencies have been developed to describe the change in the strength characteristics of rocks in the undermined massif, considering the attenuation coefficient.
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Bian, Hong Xia, Liang Zhu, and Guo Qing Hou. "Evaluation of Deformation Characters in Edgesof Hot Rolled Slab by Lode Parameter." Advanced Materials Research 668 (March 2013): 437–41. http://dx.doi.org/10.4028/www.scientific.net/amr.668.437.
Повний текст джерелаАнотація:
The hot rolling processes of slabs have been simulated by 3-D explicit dynamics Thermal-mechanical Finite Element Model (FEM) to solve the problems of edge defects. It can analyze the deformation characteristics of rolling slabs, calculate Lode parameter values in rolling deformation zone and analyze the stress-strain state in the entrance and exit of the slabs edge. Because there are the relationship between plastic deformation types and Lode parameter, and the quantitative relation metal flow and various Lode parameter. Results showed that there are complicated metal flow and various Lode parameter values in the edge of rolling deformation zone. Although there stress-strain states are various in the entrance and exit of the slab edges the μdε<0, the tensile strain increment in the direction of max principle strain was bigger than another two directions and the edges had the character of tensile deformation. This is the major cause that edge of slab is more defects than other zone.
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Mavrina, Liana Nikolaevna, and Liliya Nikolaevna Timeryanova. "Study of stress and stress resistance of preschool staff organizations: hygiene aspects." Sanitarnyj vrač (Sanitary Doctor), no. 12 (December 1, 2020): 31–37. http://dx.doi.org/10.33920/med-08-2012-04.
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The article deals with the problem of professional stress in the labor activity of employees of preschool educational organizations. Aim. The level of stress and stress resistance of preschool teachers was assessed. In accordance with the purpose of the study, the following methods were used: T.A. Nemchina, A.O. Prokhorov, Vaisman's questionnaire, McLean. The study involved 50 teachers of kindergartens of general developmental type. The materials of modern psychological and pedagogical research devoted to stress and stress resistance are analyzed and summarized. Experimental data on the state of stress resistance of preschool teachers have been obtained. In a preschool organization, employees need to reduce the level of neuropsychiatric stress, professional and organizational stress, since most of the subjects are characterized by high indicators for these parameters.
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Vu, Hung Q., and Delwyn G. Fredlund. "The prediction of one-, two-, and three-dimensional heave in expansive soils." Canadian Geotechnical Journal 41, no. 4 (August 1, 2004): 713–37. http://dx.doi.org/10.1139/t04-023.
Повний текст джерелаАнотація:
The prediction of heave in unsaturated, expansive soils has historically been studied primarily as a one-dimensional type analysis. This paper proposes a methodology that can be used for the prediction of one-, two-, or three-dimensional heave. It is suggested that negative pore-water pressures (i.e., soil suctions) can be estimated through a saturatedunsaturated seepage analysis. The results of the seepage analysis are then used as input for the prediction of displacements in a stressdeformation analysis. The formulation of the governing partial differential equations for both seepage and stressdeformation is based on the general theory of unsaturated soils using two independent stress state variables. The elasticity parameter functions required for a stressdeformation analysis can be calculated from various tests, including conventional one-dimensional oedometer tests. The proposed method is studied and tested against data collected on a case history involving a slab-on-ground floor on Regina clay. The predicted results from the two-dimensional analysis agree well with the measured data in terms of both total vertical displacements and final water contents in the soil. The results of a parametric study are also presented to show the effect of measured soil parameters (i.e., swelling index and initial void ratio) and assumed parameters (i.e., Poisson's ratio and coefficient of earth pressure at rest) on the predicted displacements.Key words: heave prediction, unsaturated soil, expansive soil, seepage analysis, stress analysis.
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Radhakrishnan, V. M., and M. Kamaraj. "An Analysis of High-Temperature Crack Growth in Type 308 Cb Stainless Steel and Its Weldment." Journal of Pressure Vessel Technology 113, no. 4 (November 1, 1991): 538–41. http://dx.doi.org/10.1115/1.2928792.
Повний текст джерелаАнотація:
Creep crack growth behavior of type 308 Cb austenitic stainless steel and its weldment has been studied in the temperature range of 875 to 1075 K under plane stress condition. The creep crack growth (CCG) rate has been correlated with parameters like stress intensity factor, K, net section stress and energy rate line integral C*. Among these parameters C* appears to describe well the CCG rate in both the cases of base metal and weldment. The rupture time tr of the cracked material has been found to be related to the energy rate line integral C*s in the steady-state condition, given by a relation of the type C*s · tr = constant.
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Gil-oulbé, Mathieu, Aleksey S. Markovich, Prosper Ngandu, and Svetlana V. Anosova. "Geometric nonlinear analysis of thin elastic paraboloid of revolution shaped shells with radial waves." RUDN Journal of Engineering Researches 21, no. 3 (December 15, 2020): 208–14. http://dx.doi.org/10.22363/2312-8143-2020-21-3-208-214.
Повний текст джерелаАнотація:
From the old ancient types of roof and dome construction, various forms of shells have been discovered which attract special attention. A shell is a structure composed of sheet material so that the curvature plays an important role in the structural behaviour, realizing its spatial form. There are different types of shells, namely thick and thin shells. G. Brankov, S.N. Krivoshapko, V.N. Ivanov, and V.A. Romanova made interesting researches of shells in the form of umbrella and umbrella-type surfaces. The term nonlinear refers to a given structure undergoing a change in stiffness in its loaded state. There are basically three different types of nonlinearities: geometric, physical and contact (boundary condition nonlinearity). For further analysis of the stress-strain state, a paraboloid with an inner radius of 4 m and an outer radius of 20 m and the number of waves equal to 6 was considered. The test shell is made of reinforced concrete. The minimum load parameter at which the shell loses stability indicates a more than three times the margin.
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Qian, Yong Mei, Ting Ting Zhou, Wei Tian, and Phaaroe Pherekhong Alphonci. "Theoretical Study on Influence of Disk Spacing on Soil Failure State of Expansion Piles under Horizontal Force." Materials Science Forum 980 (March 2020): 301–10. http://dx.doi.org/10.4028/www.scientific.net/msf.980.301.
Повний текст джерелаАнотація:
Concrete expansion pile represents a new type of high-efficiency and energy-saving variable-section filling pile and it is formed by special construction technology and equipment, this technology has been basically mature which has been gradually applied to engineering in recent years. It has high bearing capacity, small settlement and uniformity, good economic and social effect, strong anti-overturning ability and flexible design[1]. In this paper, with expansion disk spacing under bearing force as the main parameter variable, numerical simulation is carried out by ANSYS finite element software to analyze the variation relationship between horizontal displacement of the pile top, bending moment of the pile and soil stress around the pile of different disk spacing models under horizontal load, and determine the influence of disk spacing parameter on horizontal bearing capacity of the concrete expansion pile. Through the research of this paper, the influence of failure mode of concrete expansion pile and size of the disk spacing on the horizontal bearing capacity under the horizontal load is qualitatively determined, which provides a theoretical basis for improving design theory and practical application of concrete expansion pile.