A thermodynamically nonlocal damage model using a surface-residual-based nonlocal stress

ABSTRACT In this research, a surface-residual-based nonlocal stress was introduced into nonlocal damage theory to describe the long-range actions among microstructures that were excluded in the definition of Cauchy stress. By using the surface-residual-based nonlocal stress tensor, a thermodynamically consistent nonlocal integral damage model was established to simulate the strain localization behavior for elastic-brittle damage problems. In this model, both the strain and the damage were taken as nonlocal variables in the free energy function, and the integral-type damage constitutive relationships and the evolution equation were derived via thermodynamic laws in order to ensure the self-consistency within the thermodynamic framework. Based on the nonlocal damage formulations using a real nonlocal stress concept, we simulated the strain localization phenomenon in an elastic bar subjected to uniaxial tension. The results showed clear localizing and softening features of strain in the damage zone, and the boundary effects arising from the nonlocal surface residual were illuminated. Furthermore, the strain localization behaviors for different internal characteristic lengths were simulated, through which we found that the characteristic length was comparable to the size of the strain localization zone.

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A Material Model for Prediction of Fatigue Damage and Degradation of CFRP Materials

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.742.740 ◽

2017 ◽

Vol 742 ◽

pp. 740-744 ◽

Cited By ~ 2

Author(s):

Jörg Hohe ◽

Monika Gall ◽

Hannes Gauch ◽

Sascha Fliegener ◽

Zalkha Murni binti Abdul Hamid

Keyword(s):

Fatigue Damage ◽

Low Cycle Fatigue ◽

Damage Model ◽

Material Model ◽

Finite Element Program ◽

Damage Evolution Equation ◽

Brittle Damage ◽

Linear Elastic ◽

Element Program ◽

Definition Of

Objective of the present study is the definition of a material model accounting for fatigue damage and degradation. The model is formulated as a brittle damage model in the otherwise linear elastic framework. A stress driven damage evolution equation is derived from microplasticity considerations. The model is implemented as a user-defined material model into a commercial finite element program. In a comparison with experimental data in the low cycle fatigue regime, a good agreement with the numerical prediction is obtained.

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Finite Element Modeling of Damage Formation in Rubber-Toughened Polymer

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.1019 ◽

2005 ◽

Vol 297-300 ◽

pp. 1019-1024

Author(s):

Mitsugu Todo ◽

Yoshihiro Fukuya ◽

Seiya Hagihara ◽

Kazuo Arakawa

Keyword(s):

Finite Element ◽

Damage Zone ◽

Damage Model ◽

Crack Tip ◽

Optical Microscope ◽

Toughening Mechanism ◽

Element Analysis ◽

Zone Formation ◽

Macro Scale ◽

Rubber Toughened

Microscopic studies on the toughening mechanism of rubber-toughened PMMA (RTPMMA) were carried out using a polarizing optical microscope (POM) and a transmission electron microscope (TEM). POM result showed that in a typical RT-PMMA, a damage zone was developed in the vicinity of crack-tip, and therefore, it was considered that energy dissipation due to the damage zone development was the primary toughening mechanism. TEM result exhibited that the damage zone was a crowd of micro-crazes generated around rubber particles in the vicinity of notch-tip. Finite element analysis was then performed to simulate such damage formations in crack-tip region. Macro-scale and micro-scale models were developed to simulate damage zone formation and micro-crazing, respectively, with use of a damage model. It was shown that the damage model introduced was successfully applied to predict such kind of macro-damage and micro-craze formations.

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Numerical Investigation on Shear Failure of Concrete Beam Strengthened by Bonded Steel Plate

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.351-352.1552 ◽

2013 ◽

Vol 351-352 ◽

pp. 1552-1557

Author(s):

Da Guo Wang ◽

Zhi Xiu Wang ◽

Bing Xu

Keyword(s):

Numerical Investigation ◽

Concrete Beam ◽

Shear Failure ◽

Steel Plate ◽

Damage Model ◽

Adhesive Layer ◽

Aggregate Gradation ◽

Brittle Damage ◽

Plastic Yield ◽

Final Failure

Based on micromechanics, an elastic-plastic-brittle damage model of concrete beam reinforced with stick steel is proposed by considering the aggregate gradation curve algorithms and the heterogeneity. In the model, the concrete beam reinforced with stick steel is taken as a five-phase composite material that consists of the mortar matrix, coarse aggregate, bonds between mortar and aggregate, steel plate, and the adhesive layer between steel plate and concrete beam. Through the numerical investigation on shear failure of concrete beam reinforced with stick steel under external force, the results show that the model can clearly simulate microscopic plastic yield, and the initiation and extension of crack. The strength of the steel plate is relatively stronger, so it cant enhance the shear capability of the each side of the beam and the concrete beam bears the larger shear stress, which results that a large number of elements, from the supports to the load points, begin to yield. When the strain of the elements exceeds the yield strength, the elements will produce failure until the failure of the whole specimen. The final failure mode of concrete beam reinforced with stick steel is the shear failure.

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COMPUTATION FOR THE DELAMINATION IN THE LAMINATE COMPOSITE MATERIAL USING A COHESIVE ZONE MODEL BY ABAQUS

Vietnam Journal of Science and Technology ◽

10.15625/2525-2518/57/6a/14094 ◽

2020 ◽

Vol 57 (6A) ◽

pp. 61

Author(s):

Hoa Cong Vu

Keyword(s):

Finite Element ◽

Cohesive Zone Model ◽

Constitutive Relations ◽

Damage Zone ◽

Damage Model ◽

Zone Model ◽

Element Formulation ◽

Cohesive Elements ◽

Element Mesh ◽

Variable Mode

In this paper, a damage model using cohesive damage zone for the simulation of progressive delamination under variable mode is presented. The constitutive relations, based on liner softening law, are using for formulation of the delamination onset and propagation. The implementation of the cohesive elements is described, along with instructions on how to incorporate the elements into a finite element mesh. The model is implemented in a finite element formulation in ABAQUS. The numerical results given by the model are compare with experimental data

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Anisotropic nonlocal damage model for materials with intrinsic transverse isotropy

International Journal of Solids and Structures ◽

10.1016/j.ijsolstr.2018.01.020 ◽

2018 ◽

Vol 139-140 ◽

pp. 29-42 ◽

Cited By ~ 8

Author(s):

Wencheng Jin ◽

Chloé Arson

Keyword(s):

Transverse Isotropy ◽

Damage Model ◽

Nonlocal Damage

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An Homogenization-Based Nonlocal Damage Model for Brittle Materials and Applications

Computational Science – ICCS 2007 - Lecture Notes in Computer Science ◽

10.1007/978-3-540-72588-6_179 ◽

2007 ◽

pp. 1130-1137

Author(s):

Zhu Qizhi ◽

Djimedo Kondo ◽

Shao Jian-fu

Keyword(s):

Damage Model ◽

Brittle Materials ◽

Nonlocal Damage

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Further Development of the Nonlocal Damage Model of Rousselier for the Transition Regime of Fracture Toughness and Different Stress States

Volume 3: Design and Analysis ◽

10.1115/pvp2014-28714 ◽

2014 ◽

Cited By ~ 2

Author(s):

Sarah Gehrlicher ◽

Michael Seidenfuss ◽

Xaver Schuler

Keyword(s):

Fracture Toughness ◽

Damage Mechanics ◽

Damage Model ◽

Nonlocal Damage ◽

Brittle Transition ◽

Mechanics Model ◽

Element Size ◽

Transition Area ◽

Ductile To Brittle Transition ◽

Stress States

In nuclear power engineering failure has to be excluded for components with high safety relevance. Currently, safety assessments mainly use fracture mechanics concepts. Especially in the transition region of fracture toughness where limited stable crack extension may appear before cleavage fracture the currently applied methods are limited. This Paper deals with the development and verification of a closed concept for safety assessment of components over the whole range from the lower shelf to the upper shelf of fracture toughness. The results of classical used local damage mechanics models depend on the element size of the numerical model. This disadvantage can be avoided using an element size depending on microstructure. With high stress gradients and small crack growth rates usually smaller elements are required. This is in conflict with an element size depending on microstructure. By including the damage gradient as an additional degree of freedom in the damage mechanics model the results depend no longer at the element size. In the paper damage mechanics computations with a nonlocal formulation of the Rousselier model are carried out for the evaluation of the upper transition area. For the prediction of fracture toughness from the ductile to brittle transition area the nonlocal Rousselier model is coupled with the Beremin model. Thus ductile crack growth and failure by brittle fracture can be described in parallel. The numerical prediction of the behaviour of fracture toughness specimens (C(T)-specimens and SE(B)-specimens with and without side grooves) and the experimental results are highly concordant. The load displacement behavior of the specimens and the developed crack front from the ductile to brittle transition area can be well calculated with the nonlocal damage model. The instability in relation to temperature calculated with the coupled damage mechanics model predicts the variations of the experimental results very well. For further application of the nonlocal Rousselier model experiments and numerical calculations of specimens with different stress states and multi-axiality are carried out. Modified fracture toughness specimens like CTS-specimens (compact tension shear specimens) are taken to investigate the applicability of the nonlocal damage model of Rousselier to mixed mode fracture.

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