Continuum Damage Model for Ductile Materials Based on Stress-State-Dependent Damage Functions

The paper discusses an anisotropic continuum damage model. It takes into account the effect of stress state on damage and failure conditions as well as on evolution equations of damage strains. To validate the proposed framework experiments with biaxially loaded specimens and corresponding numerical simulations are performed covering a wide range of stress states. In addition, scanning electron microscope images of the fracture surfaces show different fracture modes corresponding to stress states revealed by numerical analyses.

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Modified Dyson Continuum Damage Model for Austenitic Steel Alloy

Journal of Pressure Vessel Technology ◽

10.1115/1.4039883 ◽

2018 ◽

Vol 140 (4) ◽

Author(s):

Seok Jun Kang ◽

Hoomin Lee ◽

Jae Boong Choi ◽

Moon Ki Kim

Keyword(s):

Damage Model ◽

Life Time ◽

Continuum Damage ◽

Creep Life ◽

Creep Tests ◽

Continuum Damage Model ◽

Thermal Plant ◽

Uniaxial Creep ◽

Term Creep

Ultrasuper critical (USC) thermal plants are now in operation around the globe. Their applications include superheaters and reheaters, which generally require high temperature/pressure conditions. To withstand these harsh conditions, an austenitic heat-resistant HR3C (ASME TP310NbN) steel was developed for metal creep resistance. As the designed life time of a typical thermal plant is 150,000 h, it is very important to predict long-term creep behavior. In this study, a three-state variable continuum damage model (CDM) was modified for better estimation of long-term creep life. Accelerated uniaxial creep tests were performed to determine the material parameters. Also, the rupture type and microstructural precipitation were observed by scanning electron microscopy. The creep life of HR3C steel was predicted using only relatively short-term creep test data and was then successfully verified by comparison with the long-term creep data.

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A thermodynamically consistent continuum damage model taking into account the ideas of CL Chow

International Journal of Damage Mechanics ◽

10.1177/1056789516639119 ◽

2016 ◽

Vol 25 (8) ◽

pp. 1130-1141 ◽

Cited By ~ 15

Author(s):

Michael Brünig

Keyword(s):

Damage Model ◽

Continuum Damage ◽

Continuum Damage Model

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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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