Anisotropic continuum damage constitutive model to describe the cyclic response of quasi-brittle materials: The regularized unilateral effect

In this paper two partially complementary formulations of the simple phenomenological Kachanov-Rabotnov continuum damage constitutive model are presented. The models are based on a consistent thermodynamic formulation using proper expressions for the Helmholtz free energy or its complementary form of the dissipation potential. Basic features of the models are discussed and the behaviour in tensile test and creep problems is demonstrated.

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Three dimensional statistical damage constitutive model of rock based on Griffith strength criterion

10.21203/rs.3.rs-379746/v1 ◽

2021 ◽

Author(s):

Song Chen ◽

Xiuling Cao ◽

Zhao Yang

Keyword(s):

Constitutive Model ◽

Principal Stress ◽

Damage Mechanics ◽

Brittle Materials ◽

Strength Criterion ◽

Intermediate Principal Stress ◽

True Triaxial ◽

Damage Constitutive Model ◽

Two Parameters ◽

The Relationship

Abstract According to the damage mechanics theory and Lemaitre strain equivalence theory, because most rock materials are brittle materials, Griffith strength criterion has good applicability to describe the fracture failure of brittle materials from the perspective of energy. Using a new method to describe the rock micro-element strength based on Griffith strength criterion, and assuming the micro-element strength obeys the Weibull distribution, a true triaxial constitutive model of damage softening reflecting the whole process of rock failure is established. On this basis, the influence of the two parameters in the model on the curve of the constitutive model is analyzed, and the relationship between the two parameters and the intermediate principal stress in the model is established, and the model is revised reasonably. Finally, a true triaxial damage constitutive model of rock is established. The results are in good agreement with the experimental curve, which verifies its validity and rationality. At the same time, the relationship between the damage evolution and the strain and stress is discussed, and the influence of the size of the intermediate principal stress on the relationship is analyzed in detail.

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Constitutive Description for Drawing Limit of Magnesium Alloy Tube Based on Continuum Damage Mechanics

Materials Science Forum ◽

10.4028/www.scientific.net/msf.610-613.951 ◽

2009 ◽

Vol 610-613 ◽

pp. 951-954 ◽

Cited By ~ 4

Author(s):

Ying Tong ◽

Guo Zheng Quan ◽

Bin Chen

Keyword(s):

Magnesium Alloy ◽

Constitutive Model ◽

Damage Mechanics ◽

Continuum Damage Mechanics ◽

Plastic Behavior ◽

Continuum Damage ◽

Rigid Plastic ◽

Alloy Tube ◽

Limit Graph ◽

Damage Constitutive Model

The elasto-plastic behavior and the drawing limit of a kind of magnesium alloy tube were investigated based on the foundational theories of the larger deformation of material and continuum damage constitutive model. The corresponding finite element numerical algorithm was developed based on the constitutive model. The non-mandrel drawing limit graph according to the diameter at different tube thickness of an AZ31B tube with diameter 10mm at 250°C and drawing velocity 100mm/s was achieved, and safe & unsafe area got partitioned. The maximum damage value was evaluated to be 0.324 according to height reduction ratio limit and rigid-plastic FE analysis.

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An Improved Continuum Damage Constitutive Model for Creep Deformation of Cast 20Cr32Ni1Nb Steel

Volume 5: High-Pressure Technology; ASME Nondestructive Evaluation, Diagnosis and Prognosis Division (NDPD); SPC Track for Senate ◽

10.1115/pvp2017-65583 ◽

2017 ◽

Author(s):

Xiaofeng Guo ◽

Jianming Gong ◽

Luyang Geng

Keyword(s):

Constitutive Model ◽

Creep Damage ◽

Aging Treatment ◽

Continuum Damage ◽

Variable Theory ◽

Centrifugally Cast ◽

Proposed Model ◽

Damage Constitutive Model ◽

Life Predictions

An improved continuum damage constitutive model is presented to describe the creep behavior of centrifugally cast 20Cr32Ni1Nb stainless steel. In order to determine the internal softening mechanisms of the steel, microstructural observations of damage in 20Cr32Ni1Nb steel are made using the long-term iso-thermal aging treatment. Based on the physics of microstructural processes, a two state variable theory which represents two damage mechanisms related to particle coarsening and microcrack is employed to account for tertiary creep. The kinetic equation which describes the coarsening of the precipitates with time is coupled with Liu-Murakami creep damage constitutive model. Good agreement between predicted and experimental data proves the validity of the proposed model. Compared with the failure times predicted by power law based models, such as Kachanov-Robotnov and Liu-Murakami model, life predictions based on the proposed model are found to be more reasonable over a wide stress range. Additionally, the proposed model is also applied to analyze the accumulation and development of damage in 20Cr32Ni1Nb manifold components.

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