Anisotropic damage model on the effects of damage process due to shearing stress in concrete

It is easy for composite laminates to be damaged by relative lower velocity impact which could give rise to internal delamination that will strongly weaken the compressive strength of laminates. In order to predict the occurrence of matrix failure, the elastic-brittle behaviors of fiber-reinforced composites were modeled constitutively by an anisotropic damage model. The dynamic tensile testing was performed at a constant velocity of 2 mm/min until the sample broke to achieve the mechanical parameters of E-glass reinforcements. The elastic constitutive equation and the constitutive damage model were obtained on basis of the fundamental theory of mechanics about the orthotropic constitutive of reinforcements. The methodology for this constitutive model which is developed by Hashin considered both the effect of fiber and matrix failure. Then, the developed constitutive equations were incorporated into the FE (finite element) codes, ABAQUS, through the user subroutine module to simulate the process of projectile impacting GFRP composite laminates. The results show that the material deformation reaches a maximum at 24 μs, then occurs rebound with the increase of the time. The stress of reinforcements traverse section linearly increases outward from 0 MPa to 509.8 MPa. Material damage area increases with the prolonging of time, and for a fixed time, material damage gradually increases from the edges to the center and reaches a constant value of 1, which means the rupture of the damage process.

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Rock Failure Analysis Based on a Coupled Elastoplastic-Logarithmic Damage Model

Archives of Mining Sciences ◽

10.1515/amsc-2017-0053 ◽

2017 ◽

Vol 62 (4) ◽

pp. 753-774

Author(s):

M. Abdia ◽

H. Molladavoodi ◽

H. Salarirad

Keyword(s):

Constitutive Model ◽

Plastic Flow ◽

Mechanical Response ◽

Damage Model ◽

Yield Function ◽

Irreversible Thermodynamics ◽

Stiffness Degradation ◽

Shear Stresses ◽

Rock Materials ◽

Damage Process

Abstract The rock materials surrounding the underground excavations typically demonstrate nonlinear mechanical response and irreversible behavior in particular under high in-situ stress states. The dominant causes of irreversible behavior are plastic flow and damage process. The plastic flow is controlled by the presence of local shear stresses which cause the frictional sliding. During this process, the net number of bonds remains unchanged practically. The overall macroscopic consequence of plastic flow is that the elastic properties (e.g. the stiffness of the material) are insensitive to this type of irreversible change. The main cause of irreversible changes in quasi-brittle materials such as rock is the damage process occurring within the material. From a microscopic viewpoint, damage initiates with the nucleation and growth of microcracks. When the microcracks length reaches a critical value, the coalescence of them occurs and finally, the localized meso-cracks appear. The macroscopic and phenomenological consequence of damage process is stiffness degradation, dilatation and softening response. In this paper, a coupled elastoplastic-logarithmic damage model was used to simulate the irreversible deformations and stiffness degradation of rock materials under loading. In this model, damage evolution & plastic flow rules were formulated in the framework of irreversible thermodynamics principles. To take into account the stiffness degradation and softening on post-peak region, logarithmic damage variable was implemented. Also, a plastic model with Drucker-Prager yield function was used to model plastic strains. Then, an algorithm was proposed to calculate the numerical steps based on the proposed coupled plastic and damage constitutive model. The developed model has been programmed in VC++ environment. Then, it was used as a separate and new constitutive model in DEM code (UDEC). Finally, the experimental Oolitic limestone rock behavior was simulated based on the developed model. The irreversible strains, softening and stiffness degradation were reproduced in the numerical results. Furthermore, the confinement pressure dependency of rock behavior was simulated in according to experimental observations.

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Comparison of Two Time-Integration Algorithms for an Anisotropic Damage Model Coupled with Plasticity

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.784.292 ◽

2015 ◽

Vol 784 ◽

pp. 292-299 ◽

Cited By ~ 1

Author(s):

Stephan Wulfinghoff ◽

Marek Fassin ◽

Stefanie Reese

Keyword(s):

Evolution Equations ◽

Damage Model ◽

Time Integration ◽

Three Dimensional ◽

Anisotropic Damage ◽

Euler Scheme ◽

The Finite Element Method ◽

Time Step ◽

Implicit Euler Scheme ◽

Integration Algorithms

In this work, two time integration algorithms for the anisotropic damage model proposed by Lemaitre et al. (2000) are compared. Specifically, the standard implicit Euler scheme is compared to an algorithm which implicitly solves the elasto-plastic evolution equations and explicitly computes the damage update. To this end, a three dimensional bending example is solved using the finite element method and the results of the two algorithms are compared for different time step sizes.

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Tension-Torsion High-Cycle Fatigue Life Prediction of 2A12-T4 Aluminium Alloy by Considering the Anisotropic Damage: Model, Parameter Identification, and Numerical Implementation

Acta Mechanica Solida Sinica ◽

10.1016/s0894-9166(16)30242-7 ◽

2016 ◽

Vol 29 (4) ◽

pp. 391-406 ◽

Cited By ~ 3

Author(s):

Linlin Sun ◽

Miao Zhang ◽

Weiping Hu ◽

Qingchun Meng

Keyword(s):

Fatigue Life ◽

Parameter Identification ◽

Aluminium Alloy ◽

Life Prediction ◽

High Cycle Fatigue ◽

Damage Model ◽

Fatigue Life Prediction ◽

Anisotropic Damage ◽

Numerical Implementation ◽

Cycle Fatigue

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Failure Predictions for DP Steel Cross-die Test using Anisotropic Damage

International Journal of Damage Mechanics ◽

10.1177/1056789511407646 ◽

2011 ◽

Vol 21 (5) ◽

pp. 713-754 ◽

Cited By ~ 18

Author(s):

M. S. Niazi ◽

H. H. Wisselink ◽

T. Meinders ◽

J. Huétink

Keyword(s):

Strain Rate ◽

Damage Evolution ◽

Damage Model ◽

Anisotropic Damage ◽

Continuum Damage ◽

Anisotropic Plasticity ◽

Continuum Damage Model ◽

Damage Models ◽

Isotropic Damage ◽

Failure Predictions

The Lemaitre's continuum damage model is well known in the field of damage mechanics. The anisotropic damage model given by Lemaitre is relatively simple, applicable to nonproportional loads and uses only four damage parameters. The hypothesis of strain equivalence is used to map the effective stress to the nominal stress. Both the isotropic and anisotropic damage models from Lemaitre are implemented in an in-house implicit finite element code. The damage model is coupled with an elasto-plastic material model using anisotropic plasticity (Hill-48 yield criterion) and strain-rate dependent isotropic hardening. The Lemaitre continuum damage model is based on the small strain assumption; therefore, the model is implemented in an incremental co-rotational framework to make it applicable for large strains. The damage dissipation potential was slightly adapted to incorporate a different damage evolution behavior under compression and tension. A tensile test and a low-cycle fatigue test were used to determine the damage parameters. The damage evolution was modified to incorporate strain rate sensitivity by making two of the damage parameters a function of strain rate. The model is applied to predict failure in a cross-die deep drawing process, which is well known for having a wide variety of strains and strain path changes. The failure predictions obtained from the anisotropic damage models are in good agreement with the experimental results, whereas the predictions obtained from the isotropic damage model are slightly conservative. The anisotropic damage model predicts the crack direction more accurately compared to the predictions based on principal stress directions using the isotropic damage model. The set of damage parameters, determined in a uniaxial condition, gives a good failure prediction under other triaxiality conditions.

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The Creep-Damage Model of Salt Rock Based on Fractional Derivative

Energies ◽

10.3390/en11092349 ◽

2018 ◽

Vol 11 (9) ◽

pp. 2349 ◽

Cited By ~ 15

Author(s):

Hongwei Zhou ◽

Di Liu ◽

Gang Lei ◽

Dongjie Xue ◽

Yang Zhao

Keyword(s):

Fractional Derivative ◽

Creep Test ◽

Damage Model ◽

Creep Damage ◽

Uniaxial Stress ◽

Radioactive Waste Disposal ◽

Creep Process ◽

Salt Rock ◽

Damage Process ◽

Creep Damage Model

The use of salt rock for underground radioactive waste disposal facilities requires a comprehensive analysis of the creep-damage process in salt rock. A computer-controlled creep setup was employed to carry out a creep test of salt rock that lasted as long as 359 days under a constant uniaxial stress. The acoustic emission (AE) space-time evolution and energy-releasing characteristics during the creep test were studied in the meantime. A new creep-damage model is proposed on the basis of a fractional derivative by combining the AE statistical regularity. It indicates that the AE data in the non-decay creep process of salt rock can be divided into three stages. Furthermore, the authors propose a new creep-damage model of salt rock based on a fractional derivative. The parameters in the model were determined by the Quasi-Newton method. The fitting analysis suggests that the new creep-damage model provides a precise description of full creep regions in salt rock.

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