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1.
On the basis of the sufficient consideration of vectorial characteristics of stress, a new nonlinear constitutive model for
cohesionless soil under plane strain and 3-D conditions was presented in a way that the action effects of stress vector are
decomposed into the action effect of mean effective stress and that of the stress ratio vector (ratio of deviatoric stress
vector to mean effective stress). The constitutive model can take account of the influence of both numerical and directional
changes of stress vector on deformation of soil simultaneously, and is applicable of both static and dynamic loading.
Biography: Shi Hong-yan (1964-) 相似文献
2.
《European Journal of Mechanics - A/Solids》2005,24(2):243-252
A new quasi-continuum constitutive model is established based on the randomized cohesive bonds model proposed by Gao and Klein (1998). This model bridges the microscopic discrete constitution characters and the macroscopic mechanical properties of material. In the presented constitutive model, both the bond stretch energy potential and the rotation energy potential are considered, which makes the presented constitutive model applicable to different Poisson-ratio and Young's modulus materials. By establishing a phenomenological bond stiffness function according to the complete stress–strain relationship of uniaxial tension test, the fracture criterion is directly incorporated into the constitutive model. The method requires no external fracture criterion when simulating fracture initiation and propagation, which brings convenience in the numerical simulation. At last, the presented constitutive model is applied to an example of crack growth in an isotropic solid. 相似文献
3.
The stress vector-based constitutive model for cohesionless soil, proposed by SHI Hong-yan et al., was applied to analyze
the deformation behaviors of materials subjected to various stress paths. The result of analysis shows that the constitutive
model can capture well the main deformation behavior of cohesionless soil, such as stress-strain nonlinearity, hardening property,
dilatancy, stress path dependency, non-coaxiality between the principal stress and the principal strain increment directions,
and the coupling of mean effective and deviatoric stress with deformation. In addition, the model can also take into account
the rotation of principal stress axes and the influence of intermediate principal stress on deformation and strength of soil
simultaneously. The excellent agreement between the predicted and measured behavior indicates the comprehensive applicability
of the model.
Biography: SHI Hong-yan (1962-), Associate Professor, Doctor 相似文献
4.
A physically based unified constitutive model is presented for an aircraft engine nickelbase superalloy. The model accounts for deformation modes that can be activated under different stress, time, and temperature combinations. Two internal state variables and a flow function have been utilized to prdict strain rate sensitivity, stress hold creep, strain hold relaxation, monotonic loading, cyclic loading, and thermal mechanical cycling. In the model flow function, creep deformation and plasticity deformation modes have been incorporated over a wide range of temperatures (0.4 < T/Tmelt < 0.75). The model is checked with independent isothermal and thermal mechanical experiments. Different temperature ranges are explored to assess model capabilities. 相似文献
5.
This paper describes a material model, in which the materials under consideration grow up in a particular direction while re-organizing themselves to the surroundings. The structural reorganization is modeled as the rearrangement of anisotropy. Two models are proposed; one is that the anisotropic vector is embedded just as in fiber-reinforced materials, and the other is that the vector behaves like a float. In order to apply the present model to boundary-value problems, a three-dimensional finite element formulation is obtained with reference to the total-Lagrangian approach. Here we evaluate the performance of the model in terms of anisotropic growth; (a) adaptation behavior of a quasi-isotropy in the initial state, and (b) monotonic growth in helical direction. 相似文献
6.
J.W.C. Dunlop F.D. Fischer P. Fratzl 《Journal of the mechanics and physics of solids》2010,58(8):1073-1087
It is known that cells proliferate and produce extracellular matrix in response to biochemical and mechanical stimuli. Constitutive models considering these phenomena are needed to quantitatively describe the process of tissue growth in the context of tissue engineering and regenerative medicine. In this paper we re-examine the theoretical framework provided by Ambrosi and Guana (2007) and Ambrosi and Guillou (2007). We show how a volumetric growth rate term can be obtained (both in a large and small strain setting), which is consistent with the laws of thermodynamics and then apply the model to a simple geometry of tissue growth within a circular pore. The model, despite its simplicity, is comparable with experimental measurements of tissue growth and highlights the contribution of the mechanical stresses produced during tissue growth on the growth rate itself. 相似文献
7.
K. Linnemann S. Klinkel W. Wagner 《International Journal of Solids and Structures》2009,46(5):1149-1166
This paper is concerned with a macroscopic nonlinear constitutive law for magnetostrictive alloys and ferroelectric ceramics. It accounts for the hysteresis effects which occur in the considered class of materials. The uniaxial model is thermodynamically motivated and based on the definition of a specific free energy function and a switching criterion. Furthermore, an additive split of the strains and the magnetic or electric field strength into a reversible and an irreversible part is suggested. Analog to plasticity, the irreversible quantities serve as internal variables. A one-to-one-relation between the two internal variables provides conservation of volume for the irreversible strains. The material model is able to approximate the ferromagnetic or ferroelectric hysteresis curves and the related butterfly hysteresis curves. Furthermore, an extended approach for ferrimagnetic behavior which occurs in magnetostrictive materials is presented. A main aspect of the constitutive model is its numerical treatment. The finite element method is employed to solve the coupled field problem. Here the usage of the irreversible field strength permits the application of algorithms of computational inelasticity. The algorithmic consistent tangent moduli are developed in closed form. Hence, quadratic convergence in the iterative solution scheme of governing balance equations is obtained. 相似文献
8.
《International Journal of Solids and Structures》2007,44(18-19):6080-6100
In this paper, we attempted to construct a constitutive model to deal with the phenomenon of cavitation and cavity growth in a rubber-like material subjected to an arbitrary tri-axial loading. To this end, we considered a spherical elementary representative volume in a general Rivlin’s incompressible material containing a central spherical cavity. The kinematics proposed by [Hou, H.S., Abeyaratne, R., 1992. Cavitation in elastic and elastic-plastic solids. J. Mech. Phys. Solids 40, 571–722] was adopted in order to construct an approximate but optimal field. In order to establish a suitable constitutive law for this class of materials, we utilized the homogenisation technique that permits us to calculate the average strain energy density of the volume. The cavity growth was considered through a physically realistic failure criterion. Combination of the constitutive law and the failure criterion enables us to describe correctly the global behaviour and the damage evolution of the material under tri-axial loading. It was shown that the present models can efficiently reproduce different stress states, varying from uniaxial to tri-axial tensions, observed in experimentations. Comparison between predicted results and experimental data proves that the proposed model is accurate and physically reasonable. Another advantage is that the proposed model does not need special identification work, the initial Rivlin’s law for the corresponding incompressible material is sufficient to form the new law for the compressible material resulted from cavitation procedure. 相似文献
9.
10.
This paper presents a composites-based hyperelastic constitutive model for soft tissue. Well organized soft tissue is treated as a composite in which the matrix material is embedded with a single family of aligned fibers. The fiber is modeled as a generalized neo-Hookean material in which the stiffness depends on fiber stretch. The deformation gradient is decomposed multiplicatively into two parts: a uniaxial deformation along the fiber direction and a subsequent shear deformation. This permits the fiber-matrix interaction caused by inhomogeneous deformation to be estimated by using effective properties from conventional composites theory based on small strain linear elasticity and suitably generalized to the present large deformation case. A transversely isotropic hyperelastic model is proposed to describe the mechanical behavior of fiber-reinforced soft tissue. This model is then applied to the human annulus fibrosus. Because of the layered anatomical structure of the annulus fibrosus, an orthotropic hyperelastic model of the annulus fibrosus is developed. Simulations show that the model reproduces the stress-strain response of the human annulus fibrosus accurately. We also show that the expression for the fiber-matrix shear interaction energy used in a previous phenomenological model is compatible with that derived in the present paper. 相似文献
11.
A nonlinear constitutive model for magnetostrictive materials 总被引:2,自引:0,他引:2
Xin'en Liu Xiaojing Zheng 《Acta Mechanica Sinica》2005,21(3):278-285
A general nonlinear constitutive model is proposed for magnetostrictive materials, based on the important physical fact that a nonlinear part of the elastic strain produced by a pre-stress is related to the magnetic domain rotation or movement and is responsible for the change of the maximum magnetostrictive strain with the pre-stress. To avoid the complicity of determining the tensor function describing the nonlinear elastic strain part, this paper proposes a simplified model by means of linearizing the nonlinear function. For the convenience of engineering applications, the expressions of the 3-D (bulk), 2-D (film) and 1-D (rod) models are, respectively, given for an isotropic material and their applicable ranges are also discussed. By comparison with the experimental data of a Terfenol-D rod, it is found that the proposed model can accurately predict the magnetostrictive strain curves in low, moderate and high magnetic field regions for various compressive pre-stress levels. The numerical simulation further illustrates that, for either magnetostrictive rods or thin films, the proposed model can effectively describe the effects of the pre-stress or residual stress on the magnetization and magnetostrictive strain curves, while none of the known models can capture all of them. Therefore, the proposed model enjoys higher precision and wider applicability than the previous models, especially in the region of the high field.The project supported by the National Natural Science Foundation of China (10132010 and 90405005) 相似文献
12.
Dalong Li Anne M. Robertson 《International Journal of Solids and Structures》2009,46(14-15):2920-2928
A structural multi-mechanism constitutive equation is developed to describe the nonlinear, anisotropic, inelastic mechanical behavior of cerebral arterial tissue. Elastin and collagen fibers are treated as separate components (mechanisms) of the artery. Elastin is responsible for load bearing at low strain levels while the collagen mechanism is recruited for load bearing at higher strain levels. This work builds on an earlier model in which both the elastin and collagen mechanisms are represented by isotropic response functions [Wulandana, R., Robertson, A.M., 2005. An inelastic multi-mechanism constitutive equation for cerebral arterial tissue. Biomech. Model. Mechan. 4 (4), 235–248]. Here, the anisotropic material response of the wall is introduced through the collagen mechanism which is composed of helically distributed families of fibers. The orientation of these families is described using either a finite number of fiber orientations or a fiber distribution function. The fiber orientation or dispersion function can be prescribed directly from arterial histology data, or, taking a phenomenological approach, based on data fitting from bi-axial measurements. The activation of the collagen mechanism is specified using a new fiber strain based activation criterion. The multi-mechanism constitutive equation is applied to the simple case of cylindrical inflation and material constants are determined based on available inelastic experimental data for cerebral arteries. While the proposed model captures all features of this inelastic data, there is a pressing need for further experiments to refine the model. 相似文献
13.
《International Journal of Plasticity》1998,14(7):627-646
Plastic-deformation induced anisotropy and memorization of back stress due to pre-loading affect the current loading. These phenomena are examined with tension and/or torsion tests, using SUS 304. Considering both anisotropy, and movement and memorization of back stress, equi-plastic surfaces are predicted. This explains the dependence of current loading on pre-loading well. Simulated strain paths during radial loading after shear straining show good agreement with experiments. 相似文献
14.
Konstantin Naumenko Holm Altenbach Yevgen Gorash 《Archive of Applied Mechanics (Ingenieur Archiv)》2009,79(6-7):619-630
Many materials exhibit the stress range dependent creep behavior. The power law creep observed for a certain stress range changes to the viscous type creep as the stress value decreases. Recently published experimental data for advanced heat resistant steels indicate that the high creep exponent (in the range 7–12) may decrease to the low value of approximately unity within the stress range relevant for engineering structures. The aim of this paper is to analyze the influence of the stress range dependent power-law-viscous creep transition on the behavior of structures at elevated temperature. A constitutive model for the minimum creep rate is introduced to describe both the linear and the power law creep depending upon the stress level. To demonstrate basic features of the stress range dependent creep modeling, several elementary examples from structural mechanics are presented. They include a stress relaxation problem, a beam subjected to pure bending and a pressurized thick-walled cylinder. Based on the uni-axial transition stress the transition value of the external load is estimated such that above this value the power law can be applied. For the loading levels below this value the character of the stress distribution as well as the stress values are essentially influenced by the viscous creep. 相似文献
15.
The photovoltaic industry relies heavily on solar-grade silicon multicrystals. Understanding their mechanical behavior requires the development of adequate constitutive models accounting for the effects of both high dislocation densities and complex loading situations in a wide range of temperature, strain rate, and impurity contents. The traditional model of Alexander and Haasen poses several limitations. We introduce in this work a novel constitutive model for covalent single crystals and its implementation into a rate-dependent crystal plasticity framework. It is entirely physically based on the dislocation generation, storage and annihilation processes taking place during plastic flow. The total dislocation density is segmented according to the dislocation mobility potential and their character. A dislocation multiplication law for the yield region more accurate than the one of Alexander and Haasen is proposed. The influence of additional dislocation sources created on forest trees, usually disregarded in models for semiconductors, is assessed. The dislocation velocity law combines three potentially rate-limiting mechanisms: the standard double kink mechanism, jog dragging and the influence of localized obstacles. The model is valid at finite strains, in multiple slip conditions and captures accurately the high temperature- and strain rate sensitivity of semiconductors. The experimental stress overshoot is qualitatively reproduced only when jog dragging is accounted for. Localized obstacles are shown not to have any significant effect on dislocation motion in silicon. The broader case of extrinsic semiconductors is discussed and the influence of dissolved oxygen on the upper yield stress of silicon monocrystals is successfully reproduced. 相似文献
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18.
Metal matrix composites (MMCs) generally do not follow the classical plasticity theory, even though the matrix metals do deform plastically. A tension-compression yield asymmetry is typically observed in MMCs. For particulate-reinforced MMCs, this non-classical response is mainly due to the variation of damage evolution with loading modes. In this paper, a viscoplastic multi-axial constitutive model for plastic deformation of MMCs is constructed using the Mises-Schleicher yield criterion. The subsequent plastic flow is characterized by an associated and decomposed flow rule considering effects from both deviatoric and hydrostatic stresses. This model is capable of describing the multi-axial yield and flow behavior of MMCs by using simulated or measured asymmetric tensile and compressive stress-strain responses as input. As an example, the influence of damage evolution in terms of interfacial debonding in MMCs (obtained from FEM simulations) is incorporated through the different tensile and compressive stress-strain behaviors. Applying this model to predict the torsion and the pressure-dependant tensile responses of some commonly used MMCs provides good agreement with experimental data. 相似文献
19.
Sergio A. Oliveira Marcelo A. Savi Alexander L. Kalamkarov 《Archive of Applied Mechanics (Ingenieur Archiv)》2010,80(10):1163-1175
Shape memory alloys (SMAs) are materials that, among other characteristics, have the ability to present high deformation levels
when subjected to mechanical loading, returning to their original form after a temperature change. Literature presents numerous
constitutive models that describe the phenomenological features of the thermomechanical behavior of SMAs. The present paper
introduces a novel three-dimensional constitutive model that describes the martensitic phase transformations within the scope
of standard generalized materials. The model is capable of describing the main features of the thermomechanical behavior of
SMAs by considering four macroscopic phases associated with austenitic phase and three variants of martensite. A numerical
procedure is proposed to deal with the nonlinearities of the model. Numerical simulations are carried out dealing with uniaxial
and multiaxial single-point tests showing the capability of the introduced model to describe the general behavior of SMAs.
Specifically, uniaxial tests show pseudoelasticity, shape memory effect, phase transformation due to temperature change and
internal subloops due to incomplete phase transformations. Concerning multiaxial tests, the pure shear stress and hydrostatic
tests are discussed showing qualitatively coherent results. Moreover, other tensile–shear tests are conducted modeling the
general three-dimensional behavior of SMAs. It is shown that the multiaxial results are qualitative coherent with the related
data presented in the literature. 相似文献
20.
Dynamic strain aging (DSA) is an important phenomenon in solute hardened metals and seriously affects the mechanical properties
of metals. DSA is generally induced by the interaction between the moving dislocations and the mobile solute atoms. In this
paper, only the interaction between moving dislocations and mobile solute atoms in a dislocation core area (core atmosphere)
will be taken into account. To establish the constitutive model which can describe the DSA phenomenon, we improved the Zerilli-Armstrong
dislocation-mechanics-based thermal viscoplastic constitutive relation, and added the effect of the interaction between the
moving dislocations and core atmosphere. Because the constitutive relation established is based on the Zerilli-Armstrong relation,
it can describe not only the DSA phenomenon, but also the mechanical behavior of metals over a broad range of temperatures
(77K∼1000K) and strain rate (10−4∼104 s−1). The model prediction for tantalum fits well with the experimental data.
Projected supported by the Chinese Academy of Sciences and the High Technical Project. 相似文献