On the description of ductile fracture in metals by the strain localization theory

Morin, David; Hopperstad, Odd Sture; Benallal, Ahmed

doi:10.1007/s10704-017-0236-9

Cited by 32 publications

(44 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is due to the lack of a void coalescence model, which is not considered to be crucial in the current context since strain localization (Sec. 5) often occurs at rather low levels of void growth [38]. Also, we note that the conformity between the porous plasticity model and the unit cell depends upon the stress triaxiality.…”

Section: Assessment Of the Porous Plasticity Modelmentioning

confidence: 65%

“…The strain localization analyses presented in the following are based on the imperfection band approach proposed by Rice [32]. Details regarding the method can be found elsewhere in the literature [32,37,38,55,56] and only a brief outline of the method and the main equations is presented here. In essence, ductile failure is associated with the first instance where strain localization can occur due to some initial imperfection within the material.…”

Section: Strain Localization Analysesmentioning

confidence: 99%

“…The initial porosity inside the band is set equal to f 0 = 0.005 as in the unit cell simulations. Previous studies [36,38] adopting the same numerical framework have demonstrated the capabilities of the strain localization analyses as a quantitative indicator for ductile failure. We note that void nucleation is not considered in this work, which could influence the results of the numerical analyses, in particular, for a stress-based nucleation criterion.…”

Section: Strain Localization Analysesmentioning

confidence: 99%

“…While porous plasticity models can be directly used in numerical simulations of structural components to study the structural response, such models also serve as a means to account for material softening in the strain localization analyses. Previous studies using the imperfection band approach have demonstrated its capabilities as a predictive tool in some specific cases [35,36] but have largely been focused on rateindependent material behavior [35][36][37][38]. Strain localization in ratedependent materials was examined by Pan et al [31] and their results display pronounced effects of rate sensitivity on the failure strain.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A Numerical Study on Ductile Failure of Porous Ductile Solids With Rate-Dependent Matrix Behavior

Dæhli

Morin

Benallal

et al. 2019

Journal of Applied Mechanics

Self Cite

View full text Add to dashboard Cite

This work examines the effects of loading rate on the plastic flow and ductile failure of porous solids exhibiting rate-dependent behavior relevant to many structural metals. Two different modeling approaches for ductile failure are employed and numerical analyses are performed over a wide range of strain rates. Finite element unit cell simulations are carried out to evaluate the macroscopic mechanical response and ductile failure by void coalescence for various macroscopic strain rates. The unit cell results are then used to assess the accuracy of a rate-dependent porous plasticity model, which is subsequently used in strain localization analyses based on the imperfection band approach. Strain localization analyses are conducted for (i) proportional loading paths and (ii) non-proportional loading paths obtained from finite element simulations of axisymmetric and flat tensile specimens. The effects of strain rate are most apparent on the stress–strain response, whereas the effects of strain rate on ductile failure is found to be small for the adopted rate-dependent constitutive model. However, the rate-dependent constitutive formulation tends to regularize the plastic strain field when the strain rate increases. In the unit cell simulations, this slightly increases the strain at coalescence with increasing strain rate compared to a rate-independent constitutive formulation. When the strain rate is sufficiently high, the strain at coalescence becomes constant. The strain localization analyses show a negligible effect of strain rate under proportional loading, while the effect of strain rate is more pronounced when non-proportional loading paths are assigned.

show abstract

Section: Assessment Of the Porous Plasticity Modelmentioning

confidence: 65%

Section: Strain Localization Analysesmentioning

confidence: 99%

Section: Strain Localization Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Numerical Study on Ductile Failure of Porous Ductile Solids With Rate-Dependent Matrix Behavior

Dæhli

Morin

Benallal

et al. 2019

Journal of Applied Mechanics

Self Cite

View full text Add to dashboard Cite

show abstract

“…The nominal shear tractiont (inc) 21 generated by a shear wave impinging the shear band can be obtained using equations (12) and (4) into equation (33), thus yieldingt (inc)…”

Section: Boundary Integral Equations and Numerical Proceduresmentioning

confidence: 99%

The dynamics of a shear band

Giarola

Capuani

Bigoni

2018

Journal of the Mechanics and Physics of Solids

View full text Add to dashboard Cite

A shear band of finite length, formed inside a ductile material at a certain stage of a continued homogeneous strain, provides a dynamic perturbation to an incident wave field, which strongly influences the dynamics of the material and affects its path to failure. The investigation of this perturbation is presented for a ductile metal, with reference to the incremental mechanics of a material obeying the J 2 -deformation theory of plasticity (a special form of prestressed, elastic, anisotropic, and incompressible solid). The treatment originates from the derivation of integral representations relating the incremental mechanical fields at every point of the medium to the incremental displacement jump across the shear band faces, generated by an impinging wave. The boundary integral equations (under the plane strain assumption) are numerically approached through a collocation technique, which keeps into account the singularity at the shear band tips and permits the analysis of an incident wave impinging a shear band. It is shown that the presence of the shear band induces a resonance, visible in the incremental displacement field and in the stress intensity factor at the shear band tips, which promotes shear band growth. Moreover, the waves scattered by the shear band are shown to generate a fine texture of vibrations, parallel to the shear band line and propagating at a long distance from it, but leaving a sort of conical shadow zone, which emanates from the tips of the shear band.

show abstract

Comparison between the Marciniak and Kuczyński imperfection approach and bifurcation theory in the prediction of localized necking for porous ductile materials

Nasir

Chalal

Abed‐Meraim

2022

Int J Adv Manuf Technol

View full text Add to dashboard Cite

To prevent the occurrence of localized necking, the concept of forming limit diagram is often used, thus playing an important role in sheet metal forming processes. The aim of the present study is to develop a numerical tool for the theoretical prediction of forming limit diagrams, which would be a cost-effective procedure as compared to experimental measurements. The proposed numerical tool is based on the Marciniak and Kuczyński imperfection approach combined with the Gurson-Tvergaard-Needleman damage model, which is implemented into the MATLAB program within the framework of plane-stress conditions. Forming limit diagrams have been predicted by assuming both geometric (thickness) as well as material initial imperfections in the Marciniak and Kuczyński imperfection approach. These forming limit diagrams, for different sizes of geometric or material imperfections, are also compared with the forming limit diagram obtained by using the bifurcation theory. It is shown that the bifurcationbased forming limit diagram provides an upper bound as compared to the Marciniak and Kuczyński imperfection approach predictions. The results also reveal that, irrespective of the imperfection type considered in the Marciniak and Kuczyński imperfection approach, the corresponding forming limit diagram tends to that predicted by bifurcation theory when the size of initial imperfection tends to zero. Additionally, the predicted ductility limits are lowered as the magnitude of initial imperfection increases; however, the decrease in the ductility limits at balanced biaxial tension is more significant than for the other strain-path ratios. The results for the forming limit diagrams indicate that the predicted ductility limits are more sensitive to the initial imperfection in the thickness and the isotropic hardening coefficient as compared to the other types of material imperfections. Moreover, the initial imperfection in the critical porosity is the most influential one among the Gurson-Tvergaard-Needleman damage parameters.

show abstract

On the description of ductile fracture in metals by the strain localization theory

Abstract: Numerical simulations based on the bifurcation and imperfection versions of the strain localization theory are used in this paper to predict the failure loci of metals and applied to an advanced high strength steel subjected to propor-

Cited by 32 publications

References 45 publications

A Numerical Study on Ductile Failure of Porous Ductile Solids With Rate-Dependent Matrix Behavior

A Numerical Study on Ductile Failure of Porous Ductile Solids With Rate-Dependent Matrix Behavior

The dynamics of a shear band

Comparison between the Marciniak and Kuczyński imperfection approach and bifurcation theory in the prediction of localized necking for porous ductile materials

Contact Info

Product

Resources

About