scholarly journals An anisotropic brittle damage model with a damage tensor of second order using a micromorphic approach

PAMM ◽  
2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Marek Fassin ◽  
Robert Eggersmann ◽  
Stephan Wulfinghoff ◽  
Stefanie Reese
Keyword(s):  
Damage Model ◽  
Second Order ◽  
Brittle Damage ◽  
Damage Tensor

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

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.

Finite Element Modelling of Volumetric and Shear Ductile Micro- and Macro-Fracture Processes Under Long Time Loading

2008 ◽  
Author(s):  
Lucija Pajic ◽  
Alexander A. Lukyanov
Keyword(s):  
Finite Element ◽  
Pipeline Steel ◽  
Damage Model ◽  
Shear Loading ◽  
Continuous Operation ◽  
Propagation Path ◽  
Economic Implications ◽  
Long Time ◽  
Fracture Processes ◽  
Damage Tensor

Submarine and onshore pipelines transport enormous quantities of oil and gas vital to the economies of virtually all nations. Any failure to ensure safe and continuous operation of these pipelines can have serious economic implications, damage the environment and cause fatalities. A prerequisite to safe pipeline operation is to ensure their structural integrity to a high level of reliability throughout their operational lives. This integrity may be threatened by volumetric and shear ductile micro- and macro-fracture processes under long time loading or continuous operation. In this paper a mathematically consistent damage model for predicting the damage in pipeline structures under tensile and shear loading is considered. A detailed study of widely used damage models (e.g., Lemaitre’s and Gurson’s models) has been published in the literature. It has been shown that Gurson’s damage model is not able to adequately predict fracture propagation path under shear loading, whereas Lemaitre’s damage model (Lemaitre, 1985) shows good results in this case (e.g., Hambli 2001, Mkaddem et al. 2004). The opposite effect can be observed for some materials by using Gurson’s damage model in the case of tensile loading (e.g., Tvergaard and Needleman 1984; Zhang et al. 2000; Chen and Lambert 2003; Mashayekhi et al. 2007) and wiping die bending process (Mkaddem et al. 2004). Therefore, the mathematically consistent damage model which takes into account the advantages of both Lemaitre’s and Gurson’s models has been developed. The model is based on the assumption that the damage state of materials can be described by a damage tensor ωij. This allows for definition of two scalars that are ω = ωkk/3 (the volume damage) (Lukyanov, 2004) and α = ωij′ωij′ (a norm of the damage tensor deviator ωij′ = ωij −ωδij) (Lukyanov, 2004). The ω parameter describes the accumulation of micro-pore type damage (which may disappear under compression) and the parameter α describes the shear damage. The proposed damage model has been implemented into the finite element code ABAQUS by specifying the user material routine (UMAT). Based on experimental research which has been published by Lemaitre (1985), the proposed isotropic elastoplastic damage model is validated. The results for X-70 pipeline steel are also presented, discussed and future studies are outlined.

scholarly journals A novel isotropic quasi-brittle damage model applied to LCF analyses of Al2024

2010 ◽  
Vol 32 (12) ◽  
pp. 1948-1959 ◽  
Author(s):  
O. Kintzel ◽  
S. Khan ◽  
J. Mosler
Keyword(s):  
Damage Model ◽  
Brittle Damage

Kinematic Description of Damage

1998 ◽  
Vol 65 (1) ◽  
pp. 93-98 ◽  
Author(s):  
Taehyo Park ◽  
G. Z. Voyiadjis
Keyword(s):  
Fourth Order ◽  
Damage Mechanics ◽  
Effective Strain ◽  
Continuum Damage Mechanics ◽  
Second Order ◽  
Finite Strains ◽  
Damage Effect ◽  
Energy Equivalence ◽  
Simple Mapping ◽  
Damage Tensor

In this paper the kinematics of damage for finite elastic deformations is introduced using the fourth-order damage effect tensor through the concept of the effective stress within the framework of continuum damage mechanics. However, the absence of the kinematic description of damage deformation leads one to adopt one of the following two different hypotheses. One uses either the hypothesis of strain equivalence or the hypothesis of energy equivalence in order to characterize the damage of the material. The proposed approach in this work provides a relation between the effective strain and the damage elastic strain that is also applicable to finite strains. This is accomplished in this work by directly considering the kinematics of the deformation field and furthermore it is not confined to small strains as in the case of the strain equivalence or the strain energy equivalence approaches. The proposed approach shows that it is equivalent to the hypothesis of energy equivalence for finite strains. In this work, the damage is described kinematically in the elastic domain using the fourth-order damage effect tensor which is a function of the second-order damage tensor. The damage effect tensor is explicitly characterized in terms of a kinematic measure of damage through a second-order damage tensor. The constitutive equations of the elastic-damage behavior are derived through the kinematics of damage using the simple mapping instead of the other two hypotheses.

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

2013 ◽  
Vol 671-674 ◽  
pp. 906-911
Author(s):  
Bing Xu ◽  
Da Guo Wang ◽  
Zhi Xiu Wang
Keyword(s):  
Numerical Investigation ◽  
Concrete Beam ◽  
Steel Plate ◽  
Damage Model ◽  
Adhesive Layer ◽  
Aggregate Gradation ◽  
Brittle Damage ◽  
Plastic Yield ◽  
Final Failure ◽  
Bending Failure

Based on micromechanics, an elastic-plastic-brittle damage model of concrete beam strengthened by bonded steel plate is proposed by considering the aggregate gradation curve algorithms and the heterogeneity. In this model, the concrete beam strengthened by bonded steel plate is taken as a five-phase composite material that consists of the mortar matrix, coarse aggregate, bonds between matrix and aggregate, steel plate, and the adhesive layer between steel plate and concrete beam. Through the numerical investigation on bending failure of concrete beam strengthened by bonded steel plate 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 lower and it firstly yield and damage, then the bending stress born on the steel plate is transferred to the concrete beam. This results that the inner cracks of concrete beam increase rapidly and coalesce until the failure of the whole specimen. The final failure mode of concrete beam strengthened by bonded steel plate is the ductile bending failure.

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

2017 ◽  
Vol 742 ◽  
pp. 740-744 ◽  
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.

A geometrically inspired model for brittle damage in compressible elastomers

2021 ◽  
pp. 1-39
Author(s):  
Sanhita Das ◽  
Shubham Sharma ◽  
Ananth Ramaswamy ◽  
Debasish Roy ◽  
J.N. Reddy
Keyword(s):  
Phase Field ◽  
Scale Parameter ◽  
Damage Model ◽  
Continuum Damage ◽  
Surface Integral ◽  
Brittle Damage ◽  
Damage Models ◽  
Damaged Material ◽  
Isotropic Damage ◽  
Pure Compression

Abstract Regularized continuum damage models such as those based on an order parameter (phase field) have been extensively used to characterize brittle damage of compressible elastomers. However, the prescription of the surface integral and the degradation function for stiffness lacks a physical basis. In this article we propose a continuum damage model that draws upon the postulate that a damaged material could be mathematically described as a Riemannian manifold. Working within this framework with a well defined Riemannian metric designed to capture features of isotropic damage, we prescribe a scheme to prevent damage evolution under pure compression. The result is a substantively reduced stiffness degradation due to damage before the peak response and a faster convergence rate with the length scale parameter in comparison with a second order phase field formulation that involves a quadratic degradation function. We also validate this model using results of tensile experiments on double notched plates.

Elastic Brittle Damage Model of Ni-YSZ and Predicted Stress–Strain Relations as a Function of Temperature and Porosity

2011 ◽  
Vol 8 (5) ◽  
Author(s):  
Gulfam Iqbal ◽  
Bruce Kang
Keyword(s):  
Anode Material ◽  
Damage Model ◽  
Material Degradation ◽  
Stress Strain ◽  
Element Analysis ◽  
Brittle Damage ◽  
Lower Load ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Sofc Stacks

Nickel-yttria stabilized zirconia (Ni-YSZ) is the most widely used material for solid oxide fuel cell (SOFC) anodes. Anode-supported SOFCs rely on the anode to provide mechanical strength to the positive–electrolyte–negative (PEN) structure. The stresses generated in the anode can result in the formation of microcracks that degrade its structural properties and electrochemical performance. In this paper, a brittle elastic damage model is developed for Ni-YSZ and implemented in finite element analysis with the help of a user-defined subroutine. The model is exploited to predict Ni-YSZ stress–strain relations at temperatures and porosities that are difficult to generate experimentally. It is observed that the anode material degradation depends on the level of strain regardless of the temperature at the same porosity: at higher temperature, lower load is required to produce a specified level of strain than at lower temperature. Conversely, the anode material degrades and fails at a lower level of strain at higher porosity at the same temperature. The information obtained from this research will be useful to establish material parameters to achieve optimal robustness of SOFC stacks.

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