Ductile Damage Evolution Under Different Strain Rate Conditions

2000 ◽  
Author(s):  
Nicola Bonora ◽  
Domenico Gentile ◽  
Pietro Paolo Milella ◽  
Golam Newaz ◽  
Francesco Iacoviello
Keyword(s):  
Strain Rate ◽  
Deformation Rate ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Dynamic Effect ◽  
Material Behavior ◽  
Ductile Damage ◽  
Type Model ◽  
Material Loss ◽  
Damage Models

Abstract Failure of ductile metals is always controlled at microstructural level by the formation and growth of microcavities that nucleate from inclusions embedded in the ductile matrix, also at high deformation rate. Many damage models have been proposed to describe both evolutions of these cavities under the action of increasing plastic deformation, and the associated effects on the material behavior. Basically, two classes of damage models are currently available: the Gurson’s type model and continuum damage mechanics (CDM). In the framework of CDM, Bonora (1997) proposed a non-linear damage model for ductile failure that overcome the main limitations presented by others formulations: the model is material independent and its validity under multiaxial state of stress conditions has been verified for a number of class of metals, (Bonora, 1998, Bonora and Newaz, 1997). In addition, this model has the main feature to require a limited number of physically based parameters that can be easily identified with ad hoc tensile tests. In this paper, for the first time, the effect of the strain rate on ductile damage evolution has been studied in a quantitative manner evaluating the material loss of stiffness under dynamic loading. Damage measurements on SA537 Cl 1 steel have been performed according to the multiple strain gauge technique on hourglass shaped rectangular tensile specimen. Dynamic effect was introduced performing the test at different imposed displacement rates. An extensive scanning electron microscopy analysis has been performed in order to correlate damage effects with the microstructure morphological modification as a function of the applied deformation rate.

A hybrid approach for modelling of plasticity and failure behaviour of advanced high-strength steel sheets

2012 ◽  
Vol 22 (2) ◽  
pp. 188-218 ◽  
Author(s):  
J Lian ◽  
M Sharaf ◽  
F Archie ◽  
S Münstermann
Keyword(s):  
Damage Evolution ◽  
Damage Mechanics ◽  
Hybrid Approach ◽  
High Strength Steels ◽  
High Strength ◽  
Numerical Approach ◽  
Ductile Damage ◽  
Dissipation Energy ◽  
Damage Models ◽  
Steel Sheets

The ductile damage mechanisms dominating in modern high-strength steels have emphasised the significance of the onset of damage and the subsequent damage evolution in sheet metal forming processes. This paper contributes to the modelling of the plasticity and ductile damage behaviour of a dual-phase steel sheet by proposing a new damage mechanics approach derived from the combination of different types of damage models. It addresses the influence of stress state on the plasticity behaviour and onset of damage of materials, and quantifies the microstructure degradation using a dissipation-energy-based damage evolution law. The model is implemented into ABAQUS/Explicit by means of a user material subroutine (VUMAT) and applied to the subsequent numerical simulations. A hybrid experimental and numerical approach is employed to calibrate the material parameters, and the detailed program is demonstrated. The calibrated parameters and the model are then verified by experiments at different levels, and a good agreement between the experimental and numerical results is achieved.

Cumulative Damage Mechanics: Characterization, Modeling, and Interpretation of Progressive Failure in Ceramics and Composites

2004 ◽  
Author(s):  
Michael G. Jenkins ◽  
Paul E. Labossie`re ◽  
Jonathan A. Salem
Keyword(s):  
Damage Mechanics ◽  
Progressive Failure ◽  
Ceramic Matrix Composites ◽  
Test Methods ◽  
Cumulative Damage ◽  
Material Behavior ◽  
Matrix Composites ◽  
Damage Models ◽  
Novel Design ◽  
Nonlinear Energy

Ceramic matrix composites (CMCs) have evolved to exhibit inherent damage tolerance through nonlinear energy absorption mechanisms while retaining the desirable attributes of their monolithic structural ceramic counterparts. Mathematical (analytic and numeric) models together with experimental measurements of this damage absorption have aided in understanding the thermomechanical behavior of CMCs. This understanding has led to improved test methods, better predictive modeling of material behavior, appropriate processing methods, and finally novel design methodologies for implementing CMCs. In this paper, background on CMC damage is presented, damage measurement and damage models are discussed and finally probabilistic aspects of constituent materials that can be used to illustrate the cumulative damage behavior of CMCs are described.

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

2011 ◽  
Vol 21 (5) ◽  
pp. 713-754 ◽  
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.

Modeling of the Strain Rate Dependent Material Behavior of 3D-Textile Composites with Production and Operational Defects

2011 ◽  
Vol 403-408 ◽  
pp. 651-655
Author(s):  
W. Hufenbach ◽  
M. Gude ◽  
R. Protz
Keyword(s):  
Strain Rate ◽  
Damage Mechanics ◽  
Additive Model ◽  
Experimental Tests ◽  
Continuum Damage Mechanics ◽  
Textile Composites ◽  
Material Behavior ◽  
Rate Dependent ◽  
Dynamic Tensile Loading ◽  
Good Coincidence

This paper concerned with modeling of the strain rate dependent material behavior of 3D-textile composites with simultaneous consideration of production and operational (e.g. pores or fatigue damage) defects. Therefore an additive model in the sense of continuum damage mechanics was introduced. For the model validation extensive experimental tests on glass non-crimp fabrics reinforced epoxy (GF-NCF/EP) composites are performed. The focus is put on the influence of production and fatigue related pre-damage under subsequent highly-dynamic tensile loading. The theoretical studies shows a good coincidence with the experimentally results

Development of “Material Specific” Creep Continuum Damage Mechanics-Based Constitutive Equations

2020 ◽  
Author(s):  
Ricardo Vega ◽  
Jaime A. Cano ◽  
Calvin M. Stewart
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Creep Strain ◽  
Creep Deformation ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Constitutive Models ◽  
Continuum Damage Mechanics ◽  
Creep Strain Rate ◽  
Continuum Damage

Abstract The objective of this study is to introduce a method for creating “material specific” creep continuum damage mechanics-based constitutive models. Herein, material specific is defined as a constitutive model based on the mechanism-informed minimum creep strain rate (MCSR) equations found in deformation mechanism maps and calibrated to available material data. The material specific models are created by finding the best MCSR model for a dataset. Once the best MCSR model is found, the Monkman Grant inverse relationship between the MCSR and rupture time is employed to derive a rupture equation. The equations are substituted into continuum damage mechanics-based creep strain rate and damage evolution equations to furnish predictions of creep deformation and damage. Material specific modeling allows for the derivation of creep constitutive models that can better the material behavior specific to the available data of a material. The material specific framework is also advantageous since it has a systematic framework that moves from finding the best MCSR model, to rupture time, to damage evolution and, creep strain rate. Data for Alloy P91 was evaluated and a material specific constitutive model derived. The material specific model was able to accurately predict the MCSR, creep deformation, damage, and rupture of alloy P91.

Constitutive Modeling of Damage Evolution in Semicrystalline Polyethylene

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
José A. Alvarado-Contreras ◽  
Maria A. Polak ◽  
Alexander Penlidis
Keyword(s):  
Amorphous Phase ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Texture Evolution ◽  
Continuum Damage Mechanics ◽  
Material Behavior ◽  
Phase Hardening ◽  
Strain Behavior ◽  
Proposed Model ◽  
Crystallographic Slip

In this article, the description of a novel damage-coupled constitutive formulation for the mechanical behavior of semicrystalline polyethylene is presented. The model attempts to describe the deformation and degradation processes in polyethylene considering the interplay between the amorphous and crystalline phases and following a continuum damage mechanics approach from a microstructural viewpoint. For the amorphous phase, the model is developed within a thermodynamic framework able to describe the features of the material behavior. Amorphous phase hardening is considered into the model and associated with the molecular configurations arising during the deformation process. The equation governing damage evolution is obtained by choosing a particular form based on internal energy and entropy. For the crystalline phase, the proposed model considers the deformation mechanisms by the theory of crystallographic slip and incorporates the effects of intracrystalline debonding and fragmentation. The model generated within this framework is used to simulate uniaxial tension and simple shear of high density polyethylene. The predicted stress-strain behavior and texture evolution are compared with experimental results and numerical simulations obtained from the literature. By incorporating a damage mechanics approach, the proposed model predicts the progressive loss of material stiffness attributed to the crystal fragmentation and molecular debonding of the crystal-amorphous interfaces.

scholarly journals A Review of Damage, Void Evolution, and Fatigue Life Prediction Models

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 609
Author(s):  
Hsiao Wei Lee ◽  
Cemal Basaran
Keyword(s):  
Damage Evolution ◽  
Life Prediction ◽  
Prediction Models ◽  
Damage Model ◽  
Empirical Models ◽  
Type Model ◽  
Newtonian Mechanics ◽  
Damage Models ◽  
Void Evolution ◽  
Evolution Function

Degradation, damage evolution, and fatigue models in the literature for various engineering materials, mostly metals and composites, are reviewed. For empirical models established under the framework of Newtonian mechanics, Gurson–Tvergaard–Needleman (GTN) type model, Johnson-Cook (J-C) type damage model, microplasticity model, some other micro-mechanism based damage models, and models using irreversible entropy as a metric with an empirical evolution function are thoroughly discussed. For Physics-based models, the development and applications of unified mechanics theory is reviewed.

An Anisotropic Creep Damage Model for Anisotropic Weld Metal

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
S. Peravali ◽  
T. H. Hyde ◽  
K. A. Cliffe ◽  
S. B. Leen
Keyword(s):  
Weld Metal ◽  
Test Data ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Creep Damage ◽  
Continuum Damage Mechanics ◽  
Material Behavior ◽  
Anisotropic Damage ◽  
Continuum Damage ◽  
Anisotropic Creep

Past studies from creep tests on uniaxial specimens and Bridgman notch specimens, for a P91 weld metal, showed that anisotropic behavior (more specifically transverse isotropy) occurs in the weld metal, both in terms of creep (steady-state) strain rate behavior and rupture times (viz., damage evolution). This paper describes the development of a finite element (FE) continuum damage mechanics methodology to deal with anisotropic creep and anisotropic damage for weld metal. The method employs a second order damage tensor following the work of Murakami and Ohno (1980, “A Continuum Theory of Creep and Creep Damage,” Creep in Structures, A. R. S. Ponter and D. R. Hayhurst, eds., Springer-Verlag, Berlin, pp. 422–444) along with a novel rupture stress approach to define the evolution of this tensor, taking advantage of the transverse isotropic nature of the weld metal, to achieve a reduction in the number of material constants required from test data (and hence tests) to define the damage evolution. Hill’s anisotropy potential theory is employed to model the secondary creep. The theoretical model is implemented in a material behavior subroutine within the general-purpose nonlinear FE code ABAQUS (ABAQUS User’s Manual, Version 6.6, 6006, Hibbitt, Karlsson and Sorenson, Inc., Providence, RI). The validation of the implementation against established isotropic continuum damage mechanics solutions for the isotropic case is described. A procedure for calibrating the multiaxial damage constants from notched bar test data is described for multiaxial implementations. Also described is a study on the effect of uniaxial specimen orientation on anisotropic damage evolution.

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