scholarly journals Two-Intervals Hardening Function in a Phase-Field Damage Model for the Simulation of Aluminum Alloy Ductile Behavior

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1685
Author(s):  
Vladimir Dunić ◽  
Jelena Živković ◽  
Vladimir Milovanović ◽  
Ana Pavlović ◽  
Andreja Radovanović ◽  
...  
Keyword(s):  
Phase Field ◽  
Damage Model ◽  
Uniaxial Tensile ◽  
Plasticity Model ◽  
Engineering Structures ◽  
Plastic Domain ◽  
Loading Tests ◽  
Ductile Behavior ◽  
Von Mises ◽  
Von Mises Plasticity

The aluminum alloys (AA) are among the most utilized materials in engineering structures, which induces the need for careful investigation, testing, and possibilities for accurate simulation of the structure’s response. AA 5083-H111 specimens were used to investigate the possibility of employing a Phase-Field Damage Model (PFDM) for the simulation of AA structures’ behavior. The specimens were mechanically tested by uniaxial tensile loading tests. Based on the obtained results, the PFDM was employed with a von Mises plasticity model, implemented in the Finite Element Method software. The plasticity model was extended by modification of the hardening function defined in two-intervals: a linear hardening and a Simo-type hardening. An excellent superposition of the simulation and experimental force-displacement response was recorded. These findings suggest that the AA structures’ response can be successfully simulated in the elastic-plastic domain, as well as its failure by damage being controlled.

scholarly journals A Modified Phase-Field Damage Model for Metal Plasticity at Finite Strains: Numerical Development and Experimental Validation

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 47
Author(s):  
Jelena Živković ◽  
Vladimir Dunić ◽  
Vladimir Milovanović ◽  
Ana Pavlović ◽  
Miroslav Živković
Keyword(s):  
Phase Field ◽  
Damage Evolution ◽  
Deformation Gradient ◽  
Damage Model ◽  
Steel Structures ◽  
Plasticity Model ◽  
Metal Plasticity ◽  
Damage And Fracture ◽  
Von Mises ◽  
Von Mises Plasticity

Steel structures are designed to operate in an elastic domain, but sometimes plastic strains induce damage and fracture. Besides experimental investigation, a phase-field damage model (PFDM) emerged as a cutting-edge simulation technique for predicting damage evolution. In this paper, a von Mises metal plasticity model is modified and a coupling with PFDM is improved to simulate ductile behavior of metallic materials with or without constant stress plateau after yielding occurs. The proposed improvements are: (1) new coupling variable activated after the critical equivalent plastic strain is reached; (2) two-stage yield function consisting of perfect plasticity and extended Simo-type hardening functions. The uniaxial tension tests are conducted for verification purposes and identifying the material parameters. The staggered iterative scheme, multiplicative decomposition of the deformation gradient, and logarithmic natural strain measure are employed for the implementation into finite element method (FEM) software. The coupling is verified by the ‘one element’ example. The excellent qualitative and quantitative overlapping of the force-displacement response of experimental and simulation results is recorded. The practical significances of the proposed PFDM are a better insight into the simulation of damage evolution in steel structures, and an easy extension of existing the von Mises plasticity model coupled to damage phase-field.

A General Orthotropic von Mises Plasticity Material Model With Mixed Hardening: Model Definition and Implicit Stress Integration Procedure

1996 ◽  
Vol 63 (2) ◽  
pp. 376-382 ◽  
Author(s):  
M. Kojic´ ◽  
N. Grujovic´ ◽  
R. Slavkovic´ ◽  
M. Zˇivkovic´
Keyword(s):  
Equivalent Stress ◽  
Parameter Method ◽  
Plasticity Model ◽  
Integration Procedure ◽  
Mixed Hardening ◽  
Tangent Moduli ◽  
Stress Integration ◽  
Mises Plasticity ◽  
Von Mises ◽  
Von Mises Plasticity

A general orthotropic von Mises plasticity model, with an extension of the Hill’s yield criterion to include mixed hardening, is introduced in the paper. Material constants and equivalent stress-equivalent plastic strain curves are defined in a way to suggest their experimental determination. The model represents a special case of a general anisotropic metal plasticity model proposed by the authors. An implicit stress integration procedure, representing an application of the governing parameter method (GPM) introduced by the first author, is presented. The GPM is briefly described, and the computational procedure, together with calculation of the consistent tangent moduli, are given in some detail for a general three-dimensional deformation, with direction of application to plane stress/shell conditions. Numerical examples illustrate applicability of the model and effectiveness of the computational algorithm.

Effect of Triaxiality and Lode Angle on the Plasticity Behaviour of a Ti-6Al-4V Titanium Alloy

2013 ◽  
Vol 577-578 ◽  
pp. 413-416
Author(s):  
Andrea Gilioli ◽  
Andrea Manes ◽  
Marco Giglio ◽  
Nima Allahverdizadeh
Keyword(s):  
Titanium Alloy ◽  
Tensile Tests ◽  
Constitutive Law ◽  
Plasticity Model ◽  
Virtual Test ◽  
Test Methodology ◽  
Lode Angle ◽  
Mises Plasticity ◽  
Von Mises ◽  
Von Mises Plasticity

The widespread Von Mises plasticity model fails to take the hydrostatic and the Lode angle effects into account and the assumption of this model is not valid for all types of metallic alloys. Hence in the present work the applicability of the Von Mises plasticity model in applications on a Ti-6Al-4V Titanium alloy have been analysed. A virtual test methodology, combination of experiments and numerical analysis have been developed. For this purpose various tensile tests on different specimen shapes have been carried out experimentally. These tests have been subsequently numerically reproduced to calibrate a constitutive law which fits every single test best, highlighting the possible effect of triaxiality and Lode angle on plasticity (strain hardening behaviour). An analysis of the specimen fracture surfaces have been carried out to evaluate possible effect of triaxiality and Lode angle down to a microscopic level.

A hybrid method to update stress for perfect von-Mises plasticity coupled with Lemaitre damage mechanics

2019 ◽  
Vol 37 (2) ◽  
pp. 705-729
Author(s):  
Maliheh Tavoosi ◽  
Mehrdad Sharifian ◽  
Mehrzad Sharifian
Keyword(s):  
Hybrid Method ◽  
Damage Mechanics ◽  
Damage Model ◽  
Internal Variables ◽  
Content Type ◽  
Efficient Integration ◽  
Mises Plasticity ◽  
Lemaitre Damage Model ◽  
Von Mises ◽  
Von Mises Plasticity

Purpose The purpose of this paper is to suggest a robust hybrid method for updating the stress and plastic internal variables in plasticity considering damage mechanics. Design/methodology/approach By benefiting the properties of the well-known explicit and implicit integrations, a new mixed method is derived. In fact, the advantages of the mentioned techniques are used to achieve an efficient integration. Findings The numerical studies demonstrate the high precision and robustness of the suggested algorithm. Research limitations The perfect von-Mises plasticity together with Lemaitre damage model is considered within the realm of small deformations. Practical implications Updating stress and plastic internal variables are of utmost importance in elastoplastic analyses of structures. The accuracy and efficiency of stress-updating methods significantly affect the final outcomes of nonlinear analyses. Originality/value The idea which is used to derive the hybrid method leads to an efficient integration method for updating the constitutive equations of the damage mechanics.

Modeling and Experimental Validation of Superconductor Tape Rolling

2000 ◽  
Vol 123 (4) ◽  
pp. 665-673 ◽  
Author(s):  
M. Pandheeradi ◽  
S. P. Vaze ◽  
D.-W. Yuan ◽  
H. A. Kuhn
Keyword(s):  
Electrical Power ◽  
Three Dimensional ◽  
Element Model ◽  
Rolling Process ◽  
Isotropic Hardening ◽  
Plasticity Model ◽  
Cross Sectional ◽  
Manufacturing Operations ◽  
Von Mises ◽  
Von Mises Plasticity

Efficient, defect-free manufacturing of high-temperature superconducting (HTS) wires and tapes is critical to a variety of defense and electrical power applications. To contribute to the improvement of these manufacturing operations, an analytical and experimental study of the early stages of the multipass rolling process for transforming HTS wires into tapes was conducted. The rolling process was simulated by a three-dimensional (3D) finite element model that uses the Drucker-Prager Cap plasticity model to represent the powder core and a Von-Mises plasticity model with isotropic hardening to represent the silver sheath. The predicted cross-sectional geometry of the tapes is compared with experiments. The results show that the tape cross-sectional geometry and powder core sizes can be predicted accurately. Further, alternate boundary conditions were found to have minimal effect on the predicted cross-sectional geometry for the range of reductions considered, even though the frictional shear stress distributions were significantly different.

Statistical micromechanical damage model for SH-SFRC under tensile load considering the interfacial slip-softening and matrix spalling effects

2021 ◽  
pp. 105678952110112
Author(s):  
Hehua Zhu ◽  
Xiangyang Wei ◽  
J Woody Ju ◽  
Qing Chen ◽  
Zhiguo Yan ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Steel Fiber ◽  
Damage Model ◽  
Fiber Reinforced Concrete ◽  
Uniaxial Tensile ◽  
Interfacial Slip ◽  
Fiber Reinforced ◽  
Micromechanical Damage ◽  
The Impact ◽  
Micromechanical Damage Model

Strain hardening behavior can be observed in steel fiber reinforced concretes under tensile loads. In this paper, a statistical micromechanical damage framework is presented for the strain hardening steel fiber reinforced concrete (SH-SFRC) considering the interfacial slip-softening and matrix spalling effects. With a linear slip-softening interface law, an analytical model is developed for the single steel fiber pullout behavior. The crack bridging effects are reached by averaging the contribution of the fibers with different inclined angles. Afterwards, the traditional snubbing factor is modified by considering the fiber snubbing and the matrix spalling effects. By adopting the Weibull distribution, a statistical micromechanical damage model is established with the fracture mechanics based cracking criteria and the stress transfer distance. The comparison with the experimental results demonstrates that the proposed framework is capable of reproducing the SH-SFRC’s uniaxial tensile behavior well. Moreover, the impact of the interfacial slip-softening and matrix spalling effects are further discussed with the presented framework.

Local and non-local damage model with extended stress decomposition for concrete

2021 ◽  
pp. 105678952199872
Author(s):  
Bilal Ahmed ◽  
George Z Voyiadjis ◽  
Taehyo Park
Keyword(s):  
Shear Stress ◽  
Degrees Of Freedom ◽  
Biaxial Loading ◽  
Damage Model ◽  
Local Model ◽  
Uniaxial Tensile ◽  
Gradient Theory ◽  
Principal Stresses ◽  
Stress Decomposition ◽  
Non Local

In this work, a new damage model for concrete is proposed with an extension of the stress decomposition (limited to biaxial cases), to capture shear damage due to the opposite signed principal stresses. To extract the pure shear stress, the assumption is made that one component of the shear stress is a minimum absolute of the two principal stresses. The opposite signed principal stresses are decomposed into shear stress and uniaxial tensile/compressive stress. A local model is implemented in Abaqus UMAT and it is further extended to a non-local model by utilization of the gradient theory. The concept of three length scales (tension, compression, and shear) is kept the same as the recently proposed nonlocal damage model by the authors. The nonlocal model is implemented in the Abaqus UEL-UMAT subroutine with an eight-node quadrilateral user-defined element, having five degrees of freedom at corner nodes (displacement in X/Y direction and tensile/compressive and shear nonlocal equivalent strain) and two degrees of freedom at internal nodes. Some examples of a local model including uniaxial and biaxial loading are addressed. Also, five examples of mixed crack mode and mode-I cracking are presented to comprehensively show the performance of this model.

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