Artykuły w czasopismach: „Visco-plasticity Model”

1

Wu, Li, Qing Jun Zuo i Zhong Le Lu. "Study on the Constitutive Model of Visco-Elasticity-Plasticity Considering the Rheology of Rock Mass". Advanced Materials Research 639-640 (styczeń 2013): 567–72. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.567.

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Considering the rheological mechanical characteristics of rock mass, a viscous-plastic model of rock mass which can describe the acceleration creep stage of rock mass was proposed. Moreover, combining with viscous-elastic shearing rheological model of rock mass in series, a new constitutive model of visco-elasticity-plasticity considering the rheology was constructed. Due to the shearing rheological curves of granite, the model of visco-elasticity-plasticity considering the rheology was identified and the rheological parameters of the model were obtained. The comparison between the viscous-elastic-plastic rheological model of rock mass and experimental result of granite shows that the accelerating rheological properties of rock mass can be depicted effectively by the constitutive model of visco-elasticity-plasticity considering the rheology.

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Auricchio, F., i R. L. Taylor. "A generalized visco-plasticity model and its algorithmic implementation". Computers & Structures 53, nr 3 (listopad 1994): 637–47. http://dx.doi.org/10.1016/0045-7949(94)90107-4.

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Zhang, Rong Hai, Ning Yuan Zhu i Gai Pin Cai. "Surface Effect Mechanism Analysis for Vibrational Rotary Forging". Advanced Materials Research 314-316 (sierpień 2011): 753–58. http://dx.doi.org/10.4028/www.scientific.net/amr.314-316.753.

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As a contact of vibrational rotary forging is highly nonlinear, the contact area and boundary between rotary toolhead and workpiece had more accurate calculation, made the contact boundary more tally with the actual situation. For a surface effect is of complexity for vibrational rotary forging, a vibrational rotary forging visco-elasticity plasticity model was built, and the visco-elasticity spatial matrix and the visco-plasticity spatial matrix were derived by the generalized Hooke's law in elasticity theory and the increase theory in mechanics of plasticity, then by the finite element founction of MATLAB for the surface effect analyzed during the vibrational rotary forging deformation, it is shown as blow: the surface effect should be appeared with high frequency vibration or low frequency vibration, but there are some conditions for surface effect produced during plastic process, and then the hypothesis that the friction vector is reversal of deformation load, and it is benefit to deformation process during the part of time in vibration period is validated.

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Pathrikar, Anil, Md Masiur Rahaman i D. Roy. "A thermodynamically consistent peridynamics model for visco-plasticity and damage". Computer Methods in Applied Mechanics and Engineering 348 (maj 2019): 29–63. http://dx.doi.org/10.1016/j.cma.2019.01.008.

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Jiang, Zhi Hong, i Gai Pin Cai. "Surface Effect Preparatory Research of Vibrational Rotary Forging". Advanced Materials Research 154-155 (październik 2010): 1513–17. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.1513.

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As lack of a efficiency theoretical approximate solution for the surface effect mechanism analyzed during continuing and local vibrational plastic deformation process, according to vibrational rotary forging deforming characters, a three-dimension visco-elasticity plasticity constitutive equation was built by Kelvin model and Liewei-Mises model. After this constitutive equation was to be matrixing and to be introduced to tetrahedral solid elements, a visco-elasticity spatial stiffness matrix and a visco-plasticity spatial stiffness matrix were respectively derived. According to experimental parameters given, some simulation experimental projects were designed, a FEM models were established, and some FEM experiments were done on condition that amplitude and vibrational frequency were respectively changed, then different normal load-time curves were obtained. It is shown from experiment results that surface effect will appear during vibrational rotary forging forming process with little amplitude, the surface effect is related to the amplitude and the frequency, and this effect generation should be in special conditions, then preparatory research of surface effect mechanism of continuing and local vibrational plastic deforming process.

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Wang, Ru Bin, Wei Ya Xu i Jiu Chang Zhang. "Modeling Coupled Flow-Stress-Damage during Creep Deformation". Applied Mechanics and Materials 204-208 (październik 2012): 3294–98. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.3294.

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In order to reflect the tertiary rheological characteristics of hard rocks at the high stress states, a new nonlinear visco-elastic-plastic model is proposed on the basis of linear visco-elastic-plastic model and nonlinear visco-elastic-plasticity. And then the corresponding constitutive model are deduced, which can be used for describing rocks’ long-term strength characteristics and their creep deformational behavior and time-dependent damage under interaction of coupled seepage-stress field in rock engineering. At last, considering the time effect of rock damage in the process of tertiary creep, a coupled seepage -stress creep damage model for investigating the whole creep deformation behavior, including tertiary creep failure process is established, and the related equations governing the evolution of stress, creep damage and rock permeability along with the creep deformation of rock is introduced.

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Ekh, Magnus, Robert Lillbacka i Kenneth Runesson. "A model framework for anisotropic damage coupled to crystal (visco)plasticity". International Journal of Plasticity 20, nr 12 (grudzień 2004): 2143–59. http://dx.doi.org/10.1016/j.ijplas.2004.04.007.

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Karrech, A., K. Regenauer-Lieb i T. Poulet. "A damaged visco-plasticity model for pressure and temperature sensitive geomaterials". International Journal of Engineering Science 49, nr 10 (październik 2011): 1141–50. http://dx.doi.org/10.1016/j.ijengsci.2011.05.005.

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Bartczak, Leszek, i Sebastian Owczarek. "Existence of solution for a nonlinear model of thermo-visco-plasticity". Mathematical Methods in the Applied Sciences 41, nr 10 (25.04.2018): 3533–46. http://dx.doi.org/10.1002/mma.4841.

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Suzuki, Jorge L., Maryam Naghibolhosseini i Mohsen Zayernouri. "A General Return-Mapping Framework for Fractional Visco-Elasto-Plasticity". Fractal and Fractional 6, nr 12 (1.12.2022): 715. http://dx.doi.org/10.3390/fractalfract6120715.

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We develop a fractional return-mapping framework for power-law visco-elasto-plasticity. In our approach, the fractional viscoelasticity is accounted for through canonical combinations of Scott-Blair elements to construct a series of well-known fractional linear viscoelastic models, such as Kelvin–Voigt, Maxwell, Kelvin–Zener, and Poynting–Thomson. We also consider a fractional quasi-linear version of Fung’s model to account for stress/strain nonlinearity. The fractional viscoelastic models are combined with a fractional visco-plastic device, coupled with fractional viscoelastic models involving serial combinations of Scott-Blair elements. We then develop a general return-mapping procedure, which is fully implicit for linear viscoelastic models, and semi-implicit for the quasi-linear case. We find that, in the correction phase, the discrete stress projection and plastic slip have the same form for all the considered models, although with different property and time-step-dependent projection terms. A series of numerical experiments is carried out with analytical and reference solutions to demonstrate the convergence and computational cost of the proposed framework, which is shown to be at least first-order accurate for general loading conditions. Our numerical results demonstrate that the developed framework is more flexible and preserves the numerical accuracy of existing approaches while being more computationally tractable in the visco-plastic range due to a reduction of 50% in CPU time. Our formulation is especially suited for emerging applications of fractional calculus in bio-tissues that present the hallmark of multiple viscoelastic power-laws coupled with visco-plasticity.

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Zhang, Cong, Zhende Zhu, Shu Zhu, Zhilei He, Duan Zhu, Jinzhong Liu i Songsong Meng. "Nonlinear Creep Damage Constitutive Model of Concrete Based on Fractional Calculus Theory". Materials 12, nr 9 (8.05.2019): 1505. http://dx.doi.org/10.3390/ma12091505.

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Concrete creep has become one of the major problems that threatens concrete structural development and construction. However, a reasonable and accurate calculation model for numerical analysis is the key to control and solve the creep deformation of concrete. To better describe the concrete nonlinear creep damage evolution rule, the visco-elasticity Plasticity Rheological Theory, Riemann Liouville Theory and Combined Model Theory are quoted, and the Able dashpot is used to reconstruct fractional-order soft-body composite elements to propose the expression of the stress-strain relationship of the elastomer, visco-elasticity plasticity body, and Viscoplasticity body, considering the evolution of the concrete compression damage process. A nonlinear creep damage constitutive model of concrete, based on fractional calculus theory, is conducted, and the parameters of the specific calculation method of the model are given. The influence of stress level σ, fractional order n and material parameter α on the concrete creep process is determined by a sensitivity analysis of the model parameters. The creep process and deformation amount of concrete in practical engineering can be effectively controlled by the results of the proposed sensitivity analysis. The research results can be used to provide guidance and reference for the safe construction of concrete engineering in actual practice.

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Yang, Menghao, i Miaolin Feng. "Finite element implementation of non-unified visco-plasticity model considering static recovery". Mechanics of Time-Dependent Materials 24, nr 1 (4.01.2019): 59–72. http://dx.doi.org/10.1007/s11043-018-09406-9.

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Espinosa, H. D., H.-C. Lu, P. D. Zavattieri i S. Dwivedi. "A 3-D Finite Deformation Anisotropic Visco-Plasticity Model for Fiber Composites". Journal of Composite Materials 35, nr 5 (marzec 2001): 369–410. http://dx.doi.org/10.1177/002199801772662154.

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Röger, Matthias, i Ben Schweizer. "Strain gradient visco-plasticity with dislocation densities contributing to the energy". Mathematical Models and Methods in Applied Sciences 27, nr 14 (15.11.2017): 2595–629. http://dx.doi.org/10.1142/s0218202517500531.

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We consider the energetic description of a visco-plastic evolution and derive an existence result. The energies are convex, but not necessarily quadratic. Our model is a strain gradient model in which the curl of the plastic strain contributes to the energy. Our existence results are based on a time-discretization, the limit procedure relies on Helmholtz decompositions and compensated compactness.

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Pipard, Jean Marc, Tudor Balan, Farid Abed-Meraim i Xavier Lemoine. "Physically-Motivated Elasto-Visco-Plastic Model for the Large Strain-Rate Behavior of Steels". Key Engineering Materials 554-557 (czerwiec 2013): 1164–73. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.1164.

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A physically based elasto-visco-plastic constitutive model is presented and compared to experimental results for three different mild steels. The experiments consist of tensile tests at strain rates up to 103 s-1 and reverse shear tests. The model requires significantly fewer material parameters compared to other visco-plasticity models from the literature while exhibiting very good accuracy. Accordingly, the parameter identification is simple and intuitive, requiring a relatively small set of experiments. The strain-rate sensitivity modeling is not restricted to a particular hardening law and thus provides a general framework in which advanced hardening equations can be adopted. The model was eventually used as the basis for a homogenization approach at the phase scale; preliminary investigations showed the benefit of such an approach, where microstructure-relevant data can explicitly enter the model and may be used for material design simulations.

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Sun, Ji Quan, Sheng Yang Teng, Yan Jun Yin i Chuang Niu. "Analysis of Rheological Behavior on Transformation Induced Plasticity Steel". Materials Science Forum 850 (marzec 2016): 120–27. http://dx.doi.org/10.4028/www.scientific.net/msf.850.120.

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The cupping tests under different rate demonstrated that there was a correlation between the plastic deformation and shaping time of transformation induced plasticity (TRIP) steel, illustrating that there was also the rheology in the process of plastic forming for solid metal materials. The creep experiments were carried out by Gleeble 3500 thermal simulated test machine, and Mises yield rule was used to verify the creep experiments satisfying the visco-plastic conditions when the load was greater than yield strength. The visco-plastic deformation rate of creep experiments was obtained based on Bingham model. The viscous correlation coefficient (γ) was deduced, reaching that the viscosity of TRIP steel shows deformation resistance in the process of plastic shaping. These results provide the theoretical basis for increasing the plate yield and controlling the forming rate.

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KANG, GUOZHENG, JUN DING i YUJIE LIU. "DAMAGE-COUPLED CONSTITUTIVE MODEL FOR UNIAXIAL RATCHETING AND FATIGUE FAILURE OF 304 STAINLESS STEEL". International Journal of Modern Physics B 22, nr 31n32 (30.12.2008): 5419–24. http://dx.doi.org/10.1142/s0217979208050590.

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Based on the existed experimental results of 304 stainless steel, the evolution of fatigue damage during the stress-controlled cyclic loading was discussed first. Then, a damage-coupled visco-plastic cyclic constitutive model was proposed in the framework of unified visco-plasticity and continuum damage mechanics to simulate the whole-life ratcheting and predict the fatigue failure life of the material presented during the uniaxial stress-controlled cyclic loading with non-zero mean stress. In the proposed model, the whole life ratcheting was described by employing a non-linear kinematic hardening rule, i.e., the Armstrong-Frederick model combined with the Ohno-Wang model I, and considering the effect of fatigue damage. The damage threshold was employed to determine the failure life of the material. The simulated whole-life ratcheting and predicted failure lives are in a fairly good agreement with the experimental ones of 304 stainless steel.

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Liu, Yu Jie, i Bin Qiang. "A Cyclic Constitutive Model for Metallic Foam". Advanced Materials Research 910 (marzec 2014): 285–88. http://dx.doi.org/10.4028/www.scientific.net/amr.910.285.

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Based on the obtained experimental results, the features of stress-strain behavior of the metallic foam were discussed firstly in this paper. Then, in the framework of 2M1C visco-plasticity constitutive model, a cyclic constitutive model was proposed to simulate the stress-strain responses under monotonic and cyclic compression. In proposed model, plastic strain is divided into two parts, i.e., plastic strain of matrix metal and plastic strain of voids structure, which are associated with relative density. Additionally, a kinematic hardening rule of yield surface center is used to describe ratchetting effect during cyclic loading. The simulated stress-strain responses of aluminum foam are in a good agreement with the experimental ones.

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Vodička, Roman. "Comparing various influences on adhesive contact with friction". Selected Scientific Papers - Journal of Civil Engineering 14, nr 2 (1.12.2019): 7–18. http://dx.doi.org/10.1515/sspjce-2019-0013.

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AbstractA general computational model covering many types of frictional contact interfaces between visco-elastic bodies is considered for some cases physically relevant in numerical analysis of contact in civil engineering structures. The relations between mechanical quantities and internal parameters of the model are illustrated in a couple of simplified examples including cohesive contact combined with Coulomb friction and/or interface plasticity. The computations are implemented a semi-implicit time discretisation, quadratic programming algorithms, and the boundary-element method.

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Wan, Lin Hui, Ping Cao, Yong Heng Huang, Yi Xian Wang i Xiang Yang Zhang. "Creep Test of Hard Rock and Modified Generalized Kelvin Creep Model". Applied Mechanics and Materials 90-93 (wrzesień 2011): 626–32. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.626.

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By a circular increment step load and unload method, a set of rheological experiments were performed to study the creep properties of amphibolite and the deformation data of instantaneous elasticity, instantaneous plasticity, viscoplasticity and viscoelasticity could be obtained. The results showed that: the creep threshold of amphibolite(σs1) was 25.46MPa; whenσs1s2, the proportion of plastic deformation in the total deformation was very small and the value of creep deformation always tended to a stable value; whenσ>σs2, the rock samples failed rapidly and had no obvious creep. According to the creep and failure properties of amphibolite, the generalized Kelvin creep model was acted in series with the Mohr-Coulomb criterion and a modified generalized Kelvin creep model was built and the corresponding visco-elasto-plastic constitutive relationships were deduced. The modified model could simulate visco-elasto-plastic deviatoric behavior and elasto-plastic volumetric behavior. The model parameters of amphibolite were fitted according to the data of rheological test. The testing curves were coincident well with the theoretic curves by comparison which showed the creep properties and the plastic flow of hard rock could be well simulated by the generalized Kelvin creep model.

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Guo, Jing Rui, Xian Chang Zheng, Ji Qing Zhang i Zhi Meng Zhao. "Calculation and Analysis on the Soft Soil Foundation Settlement with Elastic-Visco-Plasticity (EVP) Model". Advanced Materials Research 1145 (marzec 2018): 8–16. http://dx.doi.org/10.4028/www.scientific.net/amr.1145.8.

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The EVP model is an available method to apply to the vertical settlement of soft soil consolidation calculation and analysis. Compared with Visco-Plasticity model, it shows more consistent with the actual stress conditions of the soil. In this paper, We have extracted soil samples in BinHai garden for assay. Then through the comparison with calculating results and a long-time engineering monitoring in BinHai garden soft soil area, a feasibility EVP model study on the vertical settlement in soft soil area is peoposed. Further a consequent sedimentation forecast was made according with the EVP model calculation. In the end, the settlement influence from creep was analyzed through one-dimensional consolidation theory.

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Klein, Olaf. "Asymptotic Behaviour for a Phase-Field Model with Hysteresis in One-Dimensional Thermo-Visco-Plasticity". Applications of Mathematics 49, nr 4 (sierpień 2004): 309–41. http://dx.doi.org/10.1007/s10492-004-6402-1.

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Bhattacharyya, Mainak, David Dureisseix i Beatrice Faverjon. "Numerical homogenisation based on asymptotic theory and model reduction for coupled elastic-viscoplastic damage". International Journal of Damage Mechanics 29, nr 9 (11.06.2020): 1416–44. http://dx.doi.org/10.1177/1056789520930785.

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This article deals with damage computation of heterogeneous structures containing locally periodic micro-structures. Such heterogeneous structure is extremely expensive to simulate using classical finite element methods, as the level of discretisation required to capture the micro-structural effects is too fine. The simulation time becomes even higher when dealing with highly non-linear material behaviour, e.g. damage, plasticity and such others. Therefore, a multi-scale strategy is proposed here that facilitates the simulation of non-linear heterogeneous material behaviour in a manner that is computationally feasible. Based on the asymptotic homogenisation theory, this multi-scale technique explores the micro–macro behaviour for elasto-(visco)plasticity coupled with damage. The theory inherently segregates the heterogeneous continua into a macroscopic homogeneous structure and an underlying heterogeneous microscopic periodic unit cell. Several heterogeneous structures have been simulated using the multi-scale method along with a one-dimensional verification with respect to a reference solution. Additionally, a reduced order modelling is used to prevent large memory requirement for storing micro-structural quantities of interest.

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Naing, Myat Thu, Teuku Faisal Fathani i Wahyu Wilopo. "Estimating the Velocity of Landslide Movement Using Visco-Plastic Model in Jeruk Sub-village, Kulon Progo District, Yogyakarta, Indonesia". Journal of the Civil Engineering Forum 4, nr 3 (25.09.2018): 276. http://dx.doi.org/10.22146/jcef.35097.

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A ground movement occurred in March and November 2017 on the hills and paddy fields in Jeruk Sub-village, Kulon Progo District, Yogyakarta Special Province. The landslide movement destroyed two houses in the village and the land is still moving especially in the rainy season. The mitigation of landslide hazard requires understanding of landslide triggering factors and its movement mechanism. This paper applies the slope stability analysis and visco-plastic model to predict the movement mechanism and velocity of a translational landslide. The sliding mass is modeled as a low plasticity silt (homogenous soil). The Limit Equilibrium Method is used to estimate the safety factor, whereas the shear strength parameters on the slip surface were determined by using the back analysis approach. The results of the slope stability analysis showed that the shear strength parameters and the fluctuation of groundwater level strongly influence the stability of the landslide. From visco-plastic model simulation, this slope has slow movement velocity with the range of 11.31 to 175.88 mm/day. It is clarified that the velocity of landslide movement is influenced by soil strength parameters, coefficient of dynamic viscosity, and groundwater level fluctuation.

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Kermouche, G., N. Aleksy i J. M. Bergheau. "Viscoelastic-Viscoplastic Modelling of the Scratch Response of PMMA". Advances in Materials Science and Engineering 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/289698.

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This paper aims at understanding how to model the time-dependent behavior of PMMA during a scratch loading at a constant speed and at middle strain levels. A brief experimental study is first presented, consisting of the analysis of microscratches carried out at various scratching velocities and normal loads. The loading conditions have been chosen in such a way that neither (visco)elasticity nor (visco)plasticity of the PMMA may be neglected a priori. The main analyzed parameter is the tip penetration depth measured during the steady state. Then, a finite element model is used to investigate the potential of classical elastic-viscoplastic constitutive models to reproduce these experimental results. It is mainly shown that these models lead to unsatisfying results. More specifically, it is pointed out here that the time-independent Young modulus used in such models is not suitable. To take into account this feature, a viscoelastic-viscoplastic model based on the connection in series of a viscoelastic part with a viscoplastic part is proposed. It is shown that it leads to more acceptable results, which points out the importance of viscoelasticity in the scratch behavior of solid polymers.

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Coghe, Frederik, Wim Tirry, Luc Rabet i Paul van Houtte. "Characterization and Modeling of Twinning in a Titanium Alloy Ti-6Al-4V". Materials Science Forum 702-703 (grudzień 2011): 237–40. http://dx.doi.org/10.4028/www.scientific.net/msf.702-703.237.

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The twinning behavior of a commercial Ti-6Al-4V alloy is studied using a combined experimental and numerical approach. An extensive microstructural investigation was performed to identify and quantify the active twin systems. The mechanical behavior as a function of initial texture and strain rate was then modeled using a visco-plastic self-consistent crystal plasticity code (VPSC7). Earlier obtained quasi-static and dynamic data served to fit the parameters of the model, giving good agreement. However, even if the model gave qualitatively good predictions of the stress-strain curves and the texture evolution for the different loadings, the calculated twin fractions differed considerably of the experimental results.

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Bergheau, Jean-Michel, Josette Devaux, Ge´rard Mottet i Philippe Gilles. "Prediction of Creep Rupture of Pressure Vessels". Journal of Pressure Vessel Technology 126, nr 2 (1.05.2004): 163–68. http://dx.doi.org/10.1115/1.1687799.

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Predictions of creep rupture of a reactor pressure vessel in a severe hypothetical accident needs to accurately take into account the interactions between creep and damage phenomena. This paper presents an approach based on a model coupling elasto-visco-plasticity and damage, formulated within the framework of continuous damage theory. The model and its implementation in a finite element software are presented and special attention is devoted to the procedure enabling the identification of the parameters of the model. The approach is validated on two tests of the program “RUPTHER” which concerns A508 cl3 steel cylinder and on the EC-FOREVER experiment (A533 steel mockup) developed as part of the European Commission Program “Assessment of Reactor Vessel Integrity.”

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Dong, Yawei, Dongyang Xie, Yang Zhang i Xiong Xiao. "On the Study of Cyclic Crystal Plasticity Ratchetting Constitutive Model for Polycrystalline Pure Copper". International Journal of Applied Mechanics 11, nr 04 (maj 2019): 1950041. http://dx.doi.org/10.1142/s1758825119500418.

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With the hypothesis of a small deformation, the novel cyclic visco-plasticity constitutive model (CV-CM) is constructed to study the cyclic deformation responses of polycrystalline metals. In this model, a modified Armstrong–Frederick nonlinear kinematic hardening (NKH) law is adopted to simulate the ratchetting deformation more precisely. The cyclic hardening characteristic of FCC polycrystalline copper is investigated with the use of flow stress evolution of slip system. For the issue of the transition from single crystal to polycrystalline crystals, the explicit [Formula: see text] rule is introduced to compute the polycrystalline response. Finally, through comparison with the experimental data, the proposed model is verified. It is demonstrated that the uniaxial ratchetting response of FCC metal can be precisely captured. The ratchetting response of copper single crystal and its relation with the crystallographic directions can be exactly traced by the present model as well.

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Mucha, Marzena, Balbina Wcisło i Jerzy Pamin. "Simulation of PLC Effect Using Regularized Large-Strain Elasto-Plasticity". Materials 15, nr 12 (18.06.2022): 4327. http://dx.doi.org/10.3390/ma15124327.

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The purpose of this paper is to develop a constitutive description and to numerically simulate a propagating instability phenomenon called the Portevin–Le Chatelier (PLC) effect, which is observed for metallic materials. It manifests itself by moving plastic shear bands in the sample and serrations in the stress–strain diagram. In this paper, the PLC is modeled by geometrically non-linear thermo-visco-plasticity with the hardening function of the Estrin–McCormick type to reproduce a serrated response. To regularize softening, which in this model comes from thermal, geometrical and strain-rate effects, the viscosity and heat conductivity are incorporated. Plasticity description can additionally include degradation of the yield strength, and then the model is enhanced by higher-order gradients. Simulations are performed using AceGen/FEM. Two tensioned specimens are tested: a rod and a dog-bone sample. The first specimen is used for general verification. The results obtained for the second specimen are compared with the experimental results. Studies for different values of model parameters are performed. The results of the simulations are in good agreement with the experimental outcome and the sensitivity to model parameters is in line with the expectations for the pre-peak regime. In the presented tests, the gradient enhancement does not significantly influence the results.

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Konrad, Julian, Sebastian Pfaller i Dirk Zahn. "Multi-Scale Modelling of Plastic Deformation, Damage and Relaxation in Epoxy Resins". Polymers 14, nr 16 (9.08.2022): 3240. http://dx.doi.org/10.3390/polym14163240.

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Epoxy resin plasticity and damage was studied from molecular dynamic simulations and interpreted by the help of constitutive modelling. For the latter, we suggested a physically motivated approach that aims at interpolating two well-defined limiting cases; namely, pulling at the vanishing strain rate and very rapid deformation; here, taken as 50% of the speed of sound of the material. In turn, to consider 0.1–10-m/s-scale deformation rates, we employed a simple relaxation model featuring exponential stress decay with a relaxation time of 1.5 ns. As benchmarks, deformation and strain reversal runs were performed by molecular dynamic simulations using two different strain rates. Our analyses show the importance of molecular rearrangements within the epoxy network loops for rationalizing the strain-rate dependence of plasticity and residual stress upon strain reversal. To this end, our constitutive model reasonably reproduced experimental data of elastic and visco-elastic epoxy deformation, along with the maximum stress experienced before fracturing. Moreover, we show the importance of introducing damage elements for mimicking the mechanical behavior of epoxy resins.

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Rouse, James P., Christopher J. Hyde, Wei Sun i Thomas H. Hyde. "Comparison of several optimisation strategies for the determination of material constants in the Chaboche visco-plasticity model". Journal of Strain Analysis for Engineering Design 48, nr 6 (9.07.2013): 347–63. http://dx.doi.org/10.1177/0309324713490925.

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Chełmiński, Krzysztof, i Sebastian Owczarek. "Renormalized solutions in thermo-visco-plasticity for a Norton–Hoff type model. Part I: The truncated case". Nonlinear Analysis: Real World Applications 28 (kwiecień 2016): 140–52. http://dx.doi.org/10.1016/j.nonrwa.2015.09.008.

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Chełmiński, Krzysztof, i Sebastian Owczarek. "Renormalised solutions in thermo-visco-plasticity for a Norton–Hoff type model. Part II: The limit case". Nonlinear Analysis: Real World Applications 31 (październik 2016): 643–60. http://dx.doi.org/10.1016/j.nonrwa.2016.03.009.

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Münstermann, Sebastian, Pawel Kucharczyk, Georg Golisch i Benedikt Döbereiner. "Phenomenological Modelling of Impact Toughness Transition Behaviour". Applied Mechanics and Materials 784 (sierpień 2015): 27–34. http://dx.doi.org/10.4028/www.scientific.net/amm.784.27.

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The toughness transition behavior of ferritic steel results from the fact that two competing fracture mechanisms can be activated independently or progressively. Temperature, strain rate and the material ́s hardening properties are the major influences affecting the result of this competition between cleavage and ductile fracture mechanisms. An elastic visco-plastic plasticity model with stress-state dependent yielding and isotropic hardening forms the basis of a model to predict the Charpy impact toughness properties of steels with bcc crystal structure for transition behavior. A scalar damage variable is coupled into the yield potential in order to capture the effects of damage induced softening. The corresponding damage evolution law considers damage initiation criteria for both mentioned fracture mechanisms. Material parameter identifications and successful model application in terms of Charpy impact toughness tests are demonstrated.

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Mocko, W. "Comparison of Energy Absorption Properties of High Nitrogen Austenitic Steel and Cast Alloy Determined Using Low Velocity Perforation Test". Archives of Metallurgy and Materials 59, nr 1 (1.03.2014): 65–69. http://dx.doi.org/10.2478/amm-2014-0011.

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Abstract The results of energy absorbing analysis of VP159 austenitic steel and LH556 cast alloy were presented in this article. The assessment was carried out on the basis of drop-weight tower perforation test at impact energy equal to 500J and striker velocity equal to 12,5 m/s. Moreover, the basic mechanical properties of both tested materials were estimated in order to calibrate coefficients of the Johnson-Cook visco-plasticity model and Johnson-Cook damage initialization criterion as well. Subsequently, both models were applied for the finite element method simulation of perforation process. The reasonable agreement between measured and calculated shape of energy absorption curves were obtained for steel and cast alloy as well.

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Galán-López, Jesús, Behnam Shakerifard, Jhon Ochoa-Avendaño i Leo A. I. Kestens. "Advanced Crystal Plasticity Modeling of Multi-Phase Steels: Work-Hardening, Strain Rate Sensitivity and Formability". Applied Sciences 11, nr 13 (30.06.2021): 6122. http://dx.doi.org/10.3390/app11136122.

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This work presents an advanced crystal plasticity model for the simulation of the mechanical behavior of multiphase advanced high-strength steels. The model is based on the Visco-Plastic Self-Consistent (VPSC) model and uses information about the material’s crystallographic texture and grain morphology together with a grain constitutive law. The law used here, based on the work of Pantleon, considers how dislocations are created and annihilated, as well as how they interact with obstacles such as grain boundaries and inclusions (carbides). Additionally, strain rate sensitivity is implemented using a phenomenological expression derived from literature data that does not require any fitting parameter. The model is applied to the study of two bainitic steels obtained by applying different heat treatments. After fitting the required parameters using tensile experiments in different directions at quasi-static and high strain rates, formability properties are determined using the model for the performance of virtual experiments: uniaxial tests are used to determine r-values and stress levels and biaxial tests are used for the calculation of yield surfaces and forming limit curves.

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Strzelecki, T., i M. Bartlewska-Urban. "Numerical Calculations of the Consolidation of Flotation Waste Landfill “Zelazny Most” Based on Biot’s Model with the Kelvin - Voight Rheological Skeleton". Archives of Civil Engineering 57, nr 2 (1.06.2011): 199–213. http://dx.doi.org/10.2478/v.10169-011-0015-3.

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Abstract This paper presents simulation results of the consolidation process of the flotation waste landfill “Zelazny Most”. The mathematical model used in presented research is based on Biot’s model of consolidation and is extended with rheological skeleton. The load is the mass pressure of the landfill itself. The initial point selected for calculations was based on the ground water level calculated in a landfill. The creeping process in this waste landfill was analyzed along the north - south section. The solution is therefore 2D with the assumption of a plane strain state. Effective model parameters data were obtained in laboratory tests on the material from the waste landfill. Results obtained for a stress state in a storage state can help to determine whether the adopted linear model of visco-elastic medium does not lead to changes in the Coulomb - Mohr potential yield, showing the emergence of plasticity of material storage areas.

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Engler, Olaf, i Ole Runar Myhr. "Effect of Natural Ageing on Strength and Anisotropy in Aluminium Alloy AA 6005C". Materials Science Forum 877 (listopad 2016): 688–94. http://dx.doi.org/10.4028/www.scientific.net/msf.877.688.

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During processing of age-hardenable AA 6xxx series alloys for automotive applications the sheets may experience significant time spans between solution heat treatment at the aluminium supplier and age hardening upon the final paint bake cycle at the carmaker. Natural ageing during these pause times is known to greatly affect materials properties of autobody sheet. In the present study we explore the impact of natural ageing on the tensile properties and the in-plane anisotropy of alloy AA 6005C. Materials properties at various degrees of natural ageing are modelled with the help of a nanoscale material model NaMo, which consists of a precipitation model simulating the formation of clusters and phases upon natural ageing as input to a mechanical model simulating the evolution of yield strength and work hardening. Plastic anisotropy is modelled from the materials crystallographic texture by a visco-plastic self-consistent polycrystal-plasticity code VPSC.

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Li, Sai Yi. "Grain Refinement Efficiency in Equal Channel Angular Extrusion of FCC Metals Inferred from Crystal Plasticity Simulations of Slip Activities". Materials Science Forum 638-642 (styczeń 2010): 1971–76. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1971.

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Equal channel angular extrusion (ECAE) is a relatively new technique to produce ultrafine-grained materials by severe plastic deformation. Its efficiency of grain refinement varies with the processing route, i.e. the billet rotation () about its longitudinal axis between successive passes. The influence of processing route can not be fully explained by existing theories that consider only the macroscopic deformation features. In this study, the mesoscopic deformation behavior during multi-pass ECAE of face-centered cubic (FCC) metals was simulated using a visco-plasticity self-consistent (VPSC) polycrystal model and assuming simple shear deformation in each pass. It is shown that the slip activities vary significantly at the transitions between successive passes, depending on the die angle and processing route. The efficiencies of grain refinement in the different cases can be well correlated to the contribution of slip systems newly activated in a subsequent pass. The grain refinement is more efficient when such contributions are higher, such as in route B ( = 90) with a 90 die or route A ( = 0) with a 120 die. These crystal plasticity simulations provide insights into the efficiency of grain refinement during severe plastic deformation with strain path changes.

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Dong, Yi, Miao Juan Peng, Yong Qi Ma i Wei Feng. "Nonlinear Finite Element Research for the Rutting of Asphalt Pavement Base on Shear Stress Analysis". Applied Mechanics and Materials 97-98 (wrzesień 2011): 91–94. http://dx.doi.org/10.4028/www.scientific.net/amm.97-98.91.

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In this paper, visco-elastic-plasticity theory is employed to establish a nonlinear finite element model of the asphalt mixture pavement. The influence of pavement structure, the ability of rutting resistance of middle layer and traffic load on shear stress distribution for asphalt pavement are discussed. The numerical results show that shear stress analysis can be used to analyze the rutting of asphalt pavement. The asphalt materials of middle layer have a great impact on rutting and shear stress. Modified asphalt is a useful middle layer material to decrease the rutting, and the hard asphalt is also an economical material to reduce rutting. Overload and overpressure easily cause pavement rutting damage. Pavement longitudinal grade is not the main reason leading to rutting at the long slope, but brake frequently in the long slope is the real cause of rutting.

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Hu, Xiao Dong, i Dong Ying Ju. "Simulation of Inelastic Deformation and Thermal Mechanical Stresses in Twin-Roll Casting Process of Mg Alloy". Key Engineering Materials 340-341 (czerwiec 2007): 877–82. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.877.

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Twin-roll thin strip casting process combines casting and hot rolling process into a single step; in which melt and solid states exist in the casting region, so its deformation is more complex than rolling process. In this paper, Anand’s model, a unified visco-plasticity constitutive model, was employed to simulate the highly nonlinear behavior in the twin-roll casting process. Anand model’s parameters were regressed based on compression tests at various temperature and strain rate for magnesium alloy AZ31. To calculate the thermal mechanical stresses, the thermal flow of twin-roll casting process was simulated firstly; then stresses were calculate, in which the temperature field result of thermal flow was imposed as body load, and a small displacement load along roller tangential direction was imposed simultaneously in order to simulate rolling action. The deformation results can well describe the forward slip zone, backward slip zone and melt eddy zone in the casting region. Based on the results, the applicability of Anand’s model on twin-roll casting process was discussed.

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Galán-López, Jesús, i Javier Hidalgo. "Use of the Correlation between Grain Size and Crystallographic Orientation in Crystal Plasticity Simulations: Application to AISI 420 Stainless Steel". Crystals 10, nr 9 (16.09.2020): 819. http://dx.doi.org/10.3390/cryst10090819.

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Crystal plasticity models attempt to reproduce the complex deformation processes of polycrystalline metals based on a virtual representation of the real microstructure. When choosing this representation, a compromise must be made between level of detail at the local level and statistical significance of the aggregate properties, also taking into account the computational cost of each solution. In this work, the correlation between crystallographic orientation and grain size is considered in the definition of virtual microstructures for the simulation of the mechanical behavior of AISI 420 stainless steel (consisting of a ferrite matrix with large carbide precipitates), in order to improve the accuracy of the solution without increasing model complexity or computation time. Both full-field (DAMASK) and mean-field models (Visco Plastic Self Consistent (VPSC)) are used together in combination with experimental results to study the validity of the assumptions done in each of the models.

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Wang, Qingqing, Chengli Yang, Haifeng Yang i Yibo He. "Simulation of Mechanical Response in Machining of Ti-6Al-4V Based on Finite Element Model and Visco-Plastic Self-Consistent Model". Metals 13, nr 8 (28.07.2023): 1362. http://dx.doi.org/10.3390/met13081362.

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The predictions of mechanical responses (stress–strain variations) in the machining of Ti-6Al-4V alloy are important to analyze the deformation conditions of machining to optimize the machining parameters and investigate the generation of a machined surface. The selection of a constitutive model is an essential factor that determines the deformation behavior in the machining simulation model. In this paper, two constitutive models of a modified Johnson–Cook (JC) equation and visco-plastic self-consistent (VPSC) model were used to investigate the stress–strain evolutions in the machining process of Ti-6Al-4V. A finite element (FE) machining model was established, considering the influences of grain refinement and deformation twins, based on a modified JC equation. The VPSC model was fitted based on the macro-strain rate sensitivity of the JC equation. The prediction results of the stress–strain curves of two models were compared, and their validities were further proved. The results show that flow stress hardening and inhomogeneities are caused by multi-scale grain refinement during the machining process of Ti-6Al-4V. Five slip deformation modes and one compressive twinning mode were activated in the VPSC model to be consistent with the macro-deformation behavior predicted with the FE model. The validations show the effectiveness of the modified JC equation, considering microstructural changes and the fitted VPSC model, in predicting dynamic behavior in the machining process of Ti-6Al-4V. The results provide two aspects of macro-deformation and polycrystal plasticity to elucidate the stress variations that occur during the machining of Ti-6Al-4V.

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Torres, Dery, Shu Guo, Maria-Pilar Villar, Daniel Araujo i Rafael Estevez. "Calibration of a Cohesive Model for Fracture in Low Cross-Linked Epoxy Resins". Polymers 10, nr 12 (28.11.2018): 1321. http://dx.doi.org/10.3390/polym10121321.

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Polymer-based composites are becoming widely used for structural applications, in particular in the aeronautic industry. The present investigation focuses on the mechanical integrity of an epoxy resin of which possible damage results in limitation or early stages of dramatic failure. Therefore, a coupled experimental and numerical investigation of failure in an epoxy resin thermoset is carried out that opens the route to an overall micromechanical analysis of thermoset-based composites. In the present case, failure is preceded by noticeable plasticity in the form of shear bands similar to observations in ductile glassy polymers. Thus, an elastic-visco-plastic constitutive law initially devoted to glassy polymer is adopted that captures the rate- dependent yield stress followed by softening and progressive hardening at continued deformation. A general rate-dependent cohesive model is used to describe the failure process. The parameters involved in the description are carefully identified and used in a finite element calculation to predict the material’s toughness for different configurations. Furthermore, the present work allows investigation of nucleation and crack growth in such resins. In particular, a minimum toughness can be derived from the model which is difficult to evaluate experimentally and allows accounting for the notch effect on the onset of failure. This is thought to help in designing polymer-based composites.

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Engler, Olaf, Galyna Laptyeva, Holger Aretz i Gernot Nitzsche. "Crystal-Plasticity Simulation of the Evolution of the Matt Surface in Pack Rolling of Aluminium Foil". Materials Science Forum 794-796 (czerwiec 2014): 553–58. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.553.

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Aluminium foil is rolled double-layered during the final rolling pass. When the sheets are later separated, the inside surface is dull and the outside surface is shiny. The matt inner side is characterized by significant surface corrugations which are believed to be a precursor for the initiation of fracture upon a subsequent forming operation. Therefore, understanding of the development of the matt side of Al foil will help to control and, eventually, improve the properties of Al foil. It was the goal of the present study to correlate the development of the matt side with the spatial arrangement of the crystallographic orientations of the foil rolling texture. This approach builds on a recent project to correlate the phenomenon of roping in AA 6xxx alloy sheet for car body applications to the occurrence of band-like clusters of grains with similar crystallographic orientation. Large-scale orientation maps obtained by electron back-scattered diffraction (EBSD) were input into a visco-plastic self-consistent crystal-plasticity model to analyse the strain anisotropy caused by the spatial distribution of the various rolling texture components. The new model is applied to several Al foils with different characteristics of the matt side.

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Lamm, L., H. Holthusen, T. Brepols, S. Jockenhövel i S. Reese. "A macroscopic approach for stress-driven anisotropic growth in bioengineered soft tissues". Biomechanics and Modeling in Mechanobiology 21, nr 2 (19.01.2022): 627–45. http://dx.doi.org/10.1007/s10237-021-01554-1.

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AbstractThe simulation of growth processes within soft biological tissues is of utmost importance for many applications in the medical sector. Within this contribution, we propose a new macroscopic approach for modelling stress-driven volumetric growth occurring in soft tissues. Instead of using the standard approach of a-priori defining the structure of the growth tensor, we postulate the existence of a general growth potential. Such a potential describes all eligible homeostatic stress states that can ultimately be reached as a result of the growth process. Making use of well-established methods from visco-plasticity, the evolution of the growth-related right Cauchy–Green tensor is subsequently defined as a time-dependent associative evolution law with respect to the introduced potential. This approach naturally leads to a formulation that is able to cover both, isotropic and anisotropic growth-related changes in geometry. It furthermore allows the model to flexibly adapt to changing boundary and loading conditions. Besides the theoretical development, we also describe the algorithmic implementation and furthermore compare the newly derived model with a standard formulation of isotropic growth.

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Glavas, Vedran, Thomas Böhlke, Dominique Daniel i Christian Leppin. "Texture Based Finite Element Simulation of a Two-Step Can Forming Process". Key Engineering Materials 504-506 (luty 2012): 655–60. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.655.

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Aluminum sheets used for beverage cans show a significant anisotropic plastic material behavior in sheet metal forming operations. In a deep drawing process of cups this anisotropy leads to a non-uniform height, i.e., an earing profile. The prediction of this earing profiles is important for the optimization of the forming process. In most cases the earing behavior cannot be predicted precisely based on phenomenological material models. In the presented work a micromechanical, texture-based model is used to simulate the first two steps (cupping and redrawing) of a can forming process. The predictions of the earing profile after each step are compared to experimental data. The mechanical modeling is done with a large strain elastic visco-plastic crystal plasticity material model with Norton type flow rule for each crystal. The response of the polycrystal is approximated by a Taylor type homogenization scheme. The simulations are carried out in the framework of the finite element method. The shape of the earing profile from the finite element simulation is compared to experimental profiles.

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Szmytka, F., M. Bourgeois, T. M. L. Nguyen-Tajan, L. Remy, A. Köster i H. Maitournam. "Development of a new model of élasto-visco-plasticity. Application to the fatigue design of an exhaust manifold of a Diesel engine". Revue de Métallurgie 105, nr 6 (czerwiec 2008): 341–46. http://dx.doi.org/10.1051/metal:2008050.

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Cirigliano, Daniele, Herol Lawerence D'Souza, Felix Grimm, Peter Kutne i Manfred Aigner. "Creep-damage modelling for micro gas turbine combustion chambers lifetime prediction". Journal of the Global Power and Propulsion Society 7 (9.06.2023): 166–76. http://dx.doi.org/10.33737/jgpps/163088.

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Micro Gas Turbines (MGTs) are nowadays largely used for electrical and thermal energy production in small buildings and households. Their reliability and compactness allow them to operate for thousands of hours with minimal maintenance. However, the long exposure at high temperatures in combustion chambers can promote creep, which can induce thermal fatigue and potential failure of these components. Creep-induced damage in MGTs has not yet been thoroughly investigated, due to the lack of numerical tools able to model these strongly coupled phenomena. This study presents the development of a Fortran-based subroutine integrated into ANSYS APDL. The code allows for a life assessment based on the Lemaitre-Chaboche creep damage model. Secondary creep and stress relaxation are modeled for the high-temperature resistant alloy Inconel718. A new set of temperature-dependent parameters for the Norton equation is provided, and the method to obtain these parameters from creep rupture tests is outlined. The model is validated and shows good agreement with experimental data. The subroutine correctly reproduces visco-plasticity, stress relaxation and damage under typical MGTs operating temperatures. This model constitutes the foundation of a life-assessment analysis for combustion chambers. The results highlight the impact of temperature and creep on the component’s life and the importance of integrating life assessment analysis into the preliminary design of combustion chambers.

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Sancho, Rafael, Javier Segurado, Borja Erice, María-Jesús Pérez-Martín i Francisco Gálvez. "Crystal-Plasticity-Finite-Element Modeling of the Quasi-Static and Dynamic Response of a Directionally Solidified Nickel-Base Superalloy". Materials 13, nr 13 (5.07.2020): 2990. http://dx.doi.org/10.3390/ma13132990.

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The flow stress behaviour of a directionally solidified nickel-base superalloy, MAR-M247, is presented through the combination of experiments and crystal-plasticity simulations. The experimental campaign encompassed quasi-static and dynamic testing in the parallel and perpendicular orientation with respect to the columnar grains. The material showed low strain-rate sensitivity in all cases. Virtual samples were generated with DREAM3d and each grain orientation was established according to the DS nature of the alloy. The elasto-visco-plastic response of each crystal is given by phenomenological-base equations, considering the dislocation–dislocation interactions among different slip systems. The hardening-function constants and the strain-rate sensitivity parameter were fitted with the information from tests parallel to the grain-growth direction and the model was able to predict with accuracy the experimental response in the perpendicular direction, confirming the suitability of the model to be used as a tool for virtual testing. Simulations also revealed that in oligocrystalline structures of this type, the yield-strength value is controlled by the grains with higher Schmid factor, while this influence decreases when plastic strain increases. Moreover, the analysis of the micro-fields confirmed that grains perpendicular to the loading axis are prone to nucleate cavities since the stresses in these regions can be twice the external applied stress.

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