Micromechanically Inspired Phenomenological Damage Model

1991 ◽  
Vol 58 (2) ◽  
pp. 305-310 ◽  
Author(s):  
Dusan Krajcinovic ◽  
Michal Basista ◽  
Dragoslav Sumarac
Keyword(s):  
Energy Release Rate ◽  
Release Rate ◽  
Damage Model ◽  
Plain Concrete ◽  
Brittle Deformation ◽  
Damage Potential ◽  
Proposed Model ◽  
Tension And Compression ◽  
Deformation Processes ◽  
Damage Theory

The paper suggests a phenomenological damage theory for perfectly brittle response of solids. The theory is based on the micromechanics of brittle deformation processes. The inelastic change of the compliance is identified as the flux and a properly averaged energy release rate as the affinity. The paper identifies conditions under which the damage potential exists. The proposed model is illustrated on the examples of plain concrete specimens subjected to uniaxial tension and compression.

Un modèle thermo-plastique couplé à l'endommagement pour le béton à hautes températures

2001 ◽  
Vol 28 (4) ◽  
pp. 593-607 ◽  
Author(s):  
Wahid Nechnech ◽  
Jean-Marie Reynouard ◽  
Fekri Meftah
Keyword(s):  
Damage Mechanics ◽  
Constitutive Relations ◽  
Damage Model ◽  
Thermal Action ◽  
Plain Concrete ◽  
Continuum Damage Mechanics ◽  
Mechanical Action ◽  
Proposed Model ◽  
Damage Theory ◽  
And Performance

In this paper a new thermoplastic damage model for plain concrete subjected to combined thermal and cyclic loading is developed using the concept of plastic-work hardening and stiffness degradation in continuum damage mechanics. Two damage variables are used: one for mechanical action and the other one for thermal action. Further, thermomechanical interaction strains have been introduced to describe the influence of mechanical loading on the physical process of thermal expansion of concrete. The constitutive relations for elastoplastic responses are decoupled from the degradation damage responses by using the effective stress concept. This method provides advantages in the numerical implementation. Efficient computational algorithms for the proposed model are subsequently explored and performance of this model is demonstrated with numerical examples.Key words: damage theory, plasticity, thermal, unilateral phenomenon, thermomechanical interaction.

Fracture Properties of Surface Modification Layers Via a Modified Bi-Layer Beam Model

2018 ◽  
Vol 35 (4) ◽  
pp. 499-511
Author(s):  
H. T. Liu ◽  
M. H. Zhao ◽  
J. W. Zhang
Keyword(s):  
Residual Stress ◽  
Surface Modification ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Fracture Process ◽  
Beam Model ◽  
Element Analysis ◽  
Fracture Properties ◽  
Proposed Model

ABSTRACTA modified bi-layer beam model is proposed to study the fracture-dominated scratch process of the brittle material with surface modification layer considering residual stress. The nonlinear analytical solution of the energy release rate is derived considering the graded distribution of the elastic modulus and residual stress. Finite element analysis is also conducted. Both analytical and numerical results show that the graded distribution of the material properties and residual stress plays an important role in the fracture process. Based on the inverse analysis, the proposed model could provide a convenient way to determine the energy release rate of materials possessing a surface modification layer.

scholarly journals A Coupled Plastic Damage Model for Concrete considering the Effect of Damage on Plastic Flow

2015 ◽  
Vol 2015 ◽  
pp. 1-13
Author(s):  
Feng Zhou ◽  
Guangxu Cheng
Keyword(s):  
Damage Model ◽  
Compressive Loading ◽  
Plain Concrete ◽  
Yield Function ◽  
Reduction Factor ◽  
Loading History ◽  
Plastic Yield ◽  
Plastic Damage ◽  
Compliance Tensor ◽  
Proposed Model

A coupled plastic damage model with two damage scalars is proposed to describe the nonlinear features of concrete. The constitutive formulations are developed by assuming that damage can be represented effectively in the material compliance tensor. Damage evolution law and plastic damage coupling are described using the framework of irreversible thermodynamics. The plasticity part is developed without using the effective stress concept. A plastic yield function based on the true stress is adopted with two hardening functions, one for tensile loading history and the other for compressive loading history. To couple the damage to the plasticity, the damage parameters are introduced into the plastic yield function by considering a reduction of the plastic hardening rate. The specific reduction factor is then deduced from the compliance tensor of the damaged material. Finally, the proposed model is applied to plain concrete. Comparison between the experimental data and the numerical simulations shows that the proposed model is able to describe the main features of the mechanical performances observed in concrete material under uniaxial, biaxial, and cyclic loadings.

ANISOTROPIC DAMAGE MODELS FOR GEOMATERIALS: THEORETICAL AND NUMERICAL CHALLENGES

2014 ◽  
Vol 11 (02) ◽  
pp. 1342007 ◽  
Author(s):  
HAO XU ◽  
CHLOÉ ARSON
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Damage Model ◽  
Damage Threshold ◽  
Yield Function ◽  
Flow Rule ◽  
Anisotropic Damage ◽  
Damage Models ◽  
Associate Flow Rule

A new anisotropic damage model for rock is formulated and discussed. Flow rules are derived with the energy release rate conjugate to damage, which is thermodynamically consistent. Drucker–Prager yield function is adapted to make the damage threshold depend on damage energy release rate and to distinguish between tension and compression strength. Positivity of dissipation is ensured by using a nonassociate flow rule for damage, while nonelastic deformation due to damage is computed by an associate flow rule. Simulations show that the model meets thermodynamic requirements, follows a rigorous formulation, and predicts expected trends for damage, deformation and stiffness.

Damage Theory Based Fatigue Simulation of Concrete Structure

2015 ◽  
Vol 784 ◽  
pp. 51-58
Author(s):  
Jun Song Liang ◽  
Jie Li
Keyword(s):  
Present Model ◽  
Fatigue Behavior ◽  
Concrete Structures ◽  
Fatigue Process ◽  
Failure Patterns ◽  
Proposed Model ◽  
Finite Element Package ◽  
Tension And Compression ◽  
Damage Theory ◽  
Compressive Damage

The fatigue problem of concrete has long been studied through many different methods. However, the fatigue process and failure patterns of concrete structures have never been well simulated due to the lack of comprehensive understanding of the material properties under fatigue loads. In order to carry out an accurate simulation of the fatigue behavior of concrete structures, this paper proposes a new damage theory based fatigue constitutive model for concrete. The present model adopts two damage variables to describe the degradation of macro mechanical properties of concrete under tension and compression, respectively. And the tensile and compressive damage evolutions are related to the corresponding effective stress spaces. Specifically, by implementing the present model into the nonlinear finite element package, the bending fatigue process of a concrete beam is simulated. Meanwhile a set of numerical tests are presented, through which the validity and effectiveness of the proposed model for the simulation of concrete structures are illustrated.

Damage Analysis and Numerical Simulation for Failure Process of Extra-Long Pre-Stressed Concrete Beams

2011 ◽  
Vol 368-373 ◽  
pp. 1318-1322
Author(s):  
Jian Yuan ◽  
Wen Gang Zhu ◽  
Min Chen
Keyword(s):  
Damage Mechanics ◽  
Concrete Beams ◽  
Failure Process ◽  
Damage Model ◽  
Mechanics Model ◽  
Damage And Fracture ◽  
Tension And Compression ◽  
Damage Constitutive Model ◽  
Damage Theory ◽  
Elastic Damage

The failure process for an extra-long pre-stressed concrete beam under static loads was simulated based on the elastic damage theory with the commercial software ABAQUS. By taking account of the different damage behaviors of concrete under tension and compression conditions, a damage mechanics model with three independent parameters was derived from the elastic damage theory. By combining the proposed damage model with the ABAQUS, the damage model was added to UMAT user subroutine. This method was developed to analyze the failure process of the extra-long pre-stressed concrete beams. The theoretical results show that the proposed damage constitutive model can be applied to describe the damage and fracture behaviors of the extra-long pre-stressed concrete beams.

Calculating Energy Release Rate as a Function of Crack Length Using a Multiple-Step Crack Closure Technique in Tire Finite Element Models

2018 ◽  
Vol 46 (3) ◽  
pp. 130-152
Author(s):  
Dennis S. Kelliher
Keyword(s):  
Finite Element ◽  
Energy Release Rate ◽  
Crack Length ◽  
Energy Release ◽  
Crack Closure ◽  
Release Rate ◽  
Fatigue Behavior ◽  
Three Dimensions ◽  
Quantitative Prediction ◽  
Closure Technique

ABSTRACT When performing predictive durability analyses on tires using finite element methods, it is generally recognized that energy release rate (ERR) is the best measure by which to characterize the fatigue behavior of rubber. By addressing actual cracks in a simulation geometry, ERR provides a more appropriate durability criterion than the strain energy density (SED) of geometries without cracks. If determined as a function of crack length and loading history, and augmented with material crack growth properties, ERR allows for a quantitative prediction of fatigue life. Complications arise, however, from extra steps required to implement the calculation of ERR within the analysis process. This article presents an overview and some details of a method to perform such analyses. The method involves a preprocessing step that automates the creation of a ribbon crack within an axisymmetric-geometry finite element model at a predetermined location. After inflating and expanding to three dimensions to fully load the tire against a surface, full ribbon sections of the crack are then incrementally closed through multiple solution steps, finally achieving complete closure. A postprocessing step is developed to determine ERR as a function of crack length from this enforced crack closure technique. This includes an innovative approach to calculating ERR as the crack length approaches zero.

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