progressive failure model of heterogeneous strain-softening materials. by Robert Roy.* Boothby

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Pagination70 leaves
Number of Pages70
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Open LibraryOL19678730M

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Stress redistribution and concentration play a great role in the failure process of heterogeneous geological materials. In response to external loads, local induced stress is disturbed due to the heterogeneity on the microscopic scale or elemental scale, and damages occur when the concentrated stresses in some local elements reach the strength : Songfeng Guo, Shengwen Qi, Zhifa Zhan, Lina Ma, Ephrem Getahun Gure, Shishu Zhang.

In heterogeneous materials such as concretes or rocks, failure occurs by progressive distributed damage during which the material exhibits strain‐softening, i.e., a gradual decline of stress at increasing strain.

and brittleness of these materials is the cause of strain-softening. Its mechanism consists of progressive distributed damage, such as dis­ persed microcracking, void formation or loss of interparticle contacts.

Strain-softening occurs not only in File Size: 1MB. In heterogeneous materials such as concretes or rocks, failure occurs by progressive distributed damage during which the material exhibits strainsoftening, i.e., a gradual decline of stress. This paper presents a 3-D failure model for predicting the dynamic material response of composite laminates under impact loading.

The formulation is based on the Continuum Damage Mechanics (CDM) approach and enables the control of the energy dissipation associated with each failure mode regardless of mesh refinement and fracture plane by: \hstrsct-Closed form and tinite-element solutions are examined for \rveral problem\ \bith strain- softening materials.

In the closed form solutions, strain-softening causes localization of the strain is accompanied bb an instantaneous vanishing of the. Based on the experimental and theoretical works of Martin and Chandler () on progressive failure, Hajiabdolmajid et al.

() used a Cohesion Weakening and Friction Strengthening (CWFS) model to capture the progressive failure process. In this model, both cohesion and friction angle are expressed as functions of plastic strain ε by: 5.

The strain-softening zone does not propagate but remains confined to a single point (x = 0). Consequently, the splitting of the bar in the middle is indicated to occur at zero energy dissipation. This feature is not physically realistic. For real materials, the dissipation of energy due to failure must be finite.

The method is applied to simulate the construction and failure of the Aznalcóllar dam. The brittle foundation clay is characterised by means of a strain-softening Mohr–Coulomb elasto-plastic model. The rupture process of the foundation is associated with a progressive failure by: This paper presents a finite element approach to analyse the response of shallow foundations on soils with strain-softening behaviour.

In these soils, a progressive failure can occur owing to a reduction of strength with increasing the plastic strains induced by by: Then, a strain-softening model of heterogeneous jointed rock mass that considers statistical damage (SSD) is developed and implemented through FLAC3D simulation software.

The present work is primarily concerned with the progressive failure mechanism of a large bedding slope with a strain-softening interface. Both the laboratory tests and finite difference method (FLAC software) are employed to fulfill our purpose. Firstly, the shear properties of the interface (the mudded weak interlayer) are investigated through groups of Cited by: 4.

Progressive damage and failure for fiber-reinforced materials: ABAQUS/Standard offers a capability to model anisotropic damage in fiber-reinforced materials (“Damage and failure for fiber-reinforced composites: overview,” Section ).

The response of the undamaged material is assumed to be linearly elastic, and the model is intended to. The progressive failure of slope and stability analyses[J]. Chinese Journal of Rock Mechanics and Engineering. 19(1): [10] Adachi T, Oka F, Osaki H, et al. Soil-water coupling analysis of progressive failure in cuts with a strain softening model[M].Author: Xiao Ping Wang, Xiong Xia, Kun Hu, Jin Cai Feng.

The progressive failure of slopes is often induced by drawdown and strain-softening of the soil. Thus, the stability level of a strain-softening slope under drawdown conditions should be evaluated while considering progressive failure.

A simplified method was developed to analyze the stability of a strain-softening slope based on a new algorithm for Cited by: 3. model which exhibits strain softening.

Strain softening. unfortunately. when incorpo- rated in a computational model. exhibits undesir- able characteristics. In static problems. finite-ele- ment solutions with strain softening often exhibit a severe dependence on element mesh size because. The progressive damage model directly applied to the microstructural RVE suffers from material instability due to non-physical strain softening, leading to results in which the localization occurs in very narrow bands of by: fracturing heterogeneous materials, the lecture addresses the problem of a continuum model for strain-softening.

In a classical, local continuum, strain-softening leads to unrealistic unstable response, such that failure localizes into a layer of vanishing thickness and occurs at vanishing energy dissipation.

The existing approaches for progressive failure of material have been levels to build the heterogeneous material model, i.e. The strain-softening constitutive model was therefore used to simulate the progressive failure process of a strain-softening slope based on the gravity increase method (GIM), with.

The material point method, which combines features of finite-element and particle discretisation methods, has been extended to solve coupled flow-deformation problems in granular media. The method is applied to simulate the construction and failure Cited by:   Uniaxial stress-strain curves are derived for a mathematical model designed to represent a heterogeneous material that fails in tension by progressive fracture.

These results show qualitative agreement with the behaviour of real materials including mortars and by: 6. Modelling progressive failure in slopes of strain-softening soil ; Brief overview of available methods ; Overstressed elements in a slope and calculating excess shear stress ; Iterative FEM analyses in strain-softening soil ; Changes in water table and pore pressures ; Limit equilibrium analysis with known falure zone.

A class of materials that fracture in a stable progressive manner and recover all deformation on unloading has been described and a theory for such materials has been developed. The theory is similar to hardening plasticity but with the important addition that, subject to certain conditions, the loading function leads to a description of degradation of stiffness as Cited by: Finite element implementation of the Hoek–Brown material model with general strain softening behavior.

and progressive failure of heterogeneous coal is. Heterogeneous brittle materials such as concretes or rocks fail by progressive fracturing distributed over a finite-size zone within the material. In the continuum approximation, this zone is characterized by strain-softening, i.e., a stress-strain relation in which the maximum principal stress decreases at increasing strain.

The hyperbolic strain‐softening relationship has been introduced to simulate the postpeak behavior of liquefied materials. The analyses have shown that a progressive failure under undrained conditions may explain the observed response of the lower San Fernando dam following the earthquake.

Heterogeneous brittle materials such as concretes or rocks fail by progressive fracturing distributed over a finite-size zone within the material. In the continuum approximation, this zone is characterized by strain-softening, i.e., ~ stress-strain relation in which the maximum.

This volume constitutes the Proceedings of the IUTAM Symposium on "Analytical and Computational Fracture Mechanics of Non-homogeneous Materials", held in Cardiff from 18th to 22nd June The Symposium was convened to address and place on record topical issues in analytical and computational.

Modelling Seasonal Ratcheting and Progressive Failure in Clay Slopes: A Validation in hydro-mechanical coupling for the numerical modelling of unsaturated soil behaviour and development of nonlocal strain-softening regulatory models to reduce mesh dependency of localisation problems, the mechanism of seasonal ratcheting has been Author: Harry Postill, Neil Dixon, Gary Fowmes, Ashraf El-Hamalawi, W.

Andy Take. uses oriented damaged elasticity concepts (smeared cracking) to describe the reversible part of the material's response after cracking failure; requires that the linear elastic material model (see “Linear elastic behavior,” Section ) be used to define elastic properties; and.

Statistical damage model with strain softening and hardening for rocks under the influence of voids and volume changes. Stochastic modeling of heterogeneous materials — a process for the analysis and evaluation of alternative formulations.

Tang CA. Numerical simulation of progressive rock failure and associated by:   The book introduces both natural and man-made slopes, the nature of soils and rocks, geomorphology, geology, and the aims of slope analysis. These topics are followed by chapters about stress and strain, shear strength of rock and soils, and progressive failure of Book Edition: 1.

the material undergoes progressive microcracking manifested by strain-softening (a decrease of stress at increasing strain) [18], is still usually small in ductile fracture of metals, but in concrete it is often very large (compared to the cross section of the structure), due to the large size of aggregate (fig.

b-d). The analyses have shown that a progressive failure under undrained conditions may explain the observed response of the lower San Fernando dam following the earthquake. Stress redistribution initiated by the strain softening of liquefied materials is the main reason for undrained flow failures of dams, slopes, and foundations and can occur.

Experimentally measured values are compared with the values predicted by using these formulae. It is shown that the upper and lower bounds suggested by the ACI committee provide reliable estimates of hinge lengths for both normal and high-strength concrete flexural hinges up to 80 by: Given the extensive range and scale of non-homogeneous materials, it had to be focussed to enhance the quality and impact of the Symposium.

The range of non-homogeneous materials was limited to those that are inhomogeneous at the. Contains 55 papers from the June symposium on the fracture of non-homogeneous materials that are inhomogeneous at the macroscopic level or exhibit strain softening.

The contributors report recent advances in applying micro-mechanical modeling, macroscopic analysis, and meso-scale lattice Price: $ where the subscripts t and c refer to tension and compression, respectively; and are the equivalent plastic strains, and are the equivalent plastic strain rates, is the temperature, and are other predefined field variables.

As shown in Figure –1, when the concrete specimen is unloaded from any point on the strain softening branch of the stress-strain curves, the. FURTHER CONSIDERATION OF A MATHEMATICAL MODEL FOR PROGRESSIVE FRACTURE OF A HETEROGENEOUS MATERIAL.

Uniaxial stress-strain curves are derived for a mathematical model designed to represent a heterogeneous material that fails in tension by progressive by: 6. In ABAQUS/Explicit the metal plasticity material models can be used in conjunction with the shear and tensile failure models (“Dynamic failure models,” Section ) that are applicable in truly dynamic situations; however, the progressive damage and failure models discussed above are generally preferred.

The Post-Failure Behavior's Prediction of CFRP Parts under Dynamic Loads Most of the carmakers show a clear interest in the replacement of metal by continuous carbon fiber composites to reach their targets in terms of lightweighting while keeping or improving the global performances of each new by: 1.Rock as a natural material is heterogeneous.

Rock material consists of minerals, crystals, cement, grains, and microcracks. Each component of rock has a different mechanical behavior under applied loading condition. Therefore, rock component distribution has an important effect on rock mechanical behavior, especially in the postpeak region.

In this paper, the rock sample Cited by: 2.

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