scholarly journals Numerical Simulation of Fatigue Crack Propagation in WC/Co based on a Continuum Damage Mechanics Approach

2014 ◽  
Vol 3 ◽  
pp. 1518-1523 ◽  
Author(s):  
Utku Ahmet Özden ◽  
Alexander Bezold ◽  
Christoph Broeckmann
Keyword(s):  
Numerical Simulation ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Continuum Damage

Fatigue Crack Modeling and Simulation Based on Continuum Damage Mechanics

2006 ◽  
Vol 129 (1) ◽  
pp. 96-102 ◽  
Author(s):  
Masakazu Takagaki ◽  
Toshiya Nakamura
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Continuum Damage Mechanics ◽  
Fatigue Loading ◽  
Present Theory ◽  
Continuum Damage ◽  
Cycle Fatigue

Numerical simulation of fatigue crack propagation based on fracture mechanics and the conventional finite element method requires a huge amount of computational resources when the cracked structure shows a complicated condition such as the multiple site damage or thermal fatigue. The objective of the present study is to develop a simulation technique for fatigue crack propagation that can be applied to complex situations by employing the continuum damage mechanics (CDM). An anisotropic damage tensor is defined to model a macroscopic fatigue crack. The validity of the present theory is examined by comparing the elastic stress distributions around the crack tip with those obtained by a conventional method. Combined with a nonlinear elasto-plastic constitutive equation, numerical simulations are conducted for low cycle fatigue crack propagation in a plate with one or two cracks. The results show good agreement with the experiments. Finally, propagations of multiply distributed cracks under low cycle fatigue loading are simulated to demonstrate the potential application of the present method.

Fatigue Crack Modeling and Simulation Based on Continuum Damage Mechanics

2004 ◽  
Author(s):  
Masakazu Takagaki ◽  
Toshiya Nakamura
Keyword(s):  
Fatigue Crack ◽  
Fracture Mechanics ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Crack Opening ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Cycle Fatigue

Numerical simulation of fatigue crack propagation based on fracture mechanics and conventional finite element method requires huge amount of computational resources when cracked structure is subjected to complicated condition such as the cases of multiple site damage or thermal fatigue. The objective of the present study is to resolve this difficulty by employing the continuum damage mechanics (CDM). An anisotropic damage variable is defined to model a macroscopic fatigue crack and its validity is examined by comparing the stress distributions around the crack with those obtained by an ordinary fracture mechanics method. Together with the assumptions on crack opening/closing and damage evolution, numerical simulations are conducted for low cycle fatigue crack propagation behaviors in a plate with single and two cracks. The results show good agreement with the experiments. Finally, propagations of multiply distributed cracks under low cycle fatigue loading are simulated to demonstrate the potential applicability of the present method.

Numerical simulation of fatigue crack propagation: A case study of defected steam pipeline

2019 ◽  
Vol 106 ◽  
pp. 104165
Author(s):  
B. Aleksić ◽  
A. Grbović ◽  
Lj. Milović ◽  
A. Hemer ◽  
V. Aleksić
Keyword(s):  
Numerical Simulation ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Steam Pipeline

Parameter Calibration for Continuum Damage Mechanics Models to Simulate Ductile Fracture of High Strength Pipeline Steels

2019 ◽  
Author(s):  
Filip Van den Abeele
Keyword(s):  
Crack Propagation ◽  
Ductile Fracture ◽  
Damage Mechanics ◽  
Void Nucleation ◽  
High Strength ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Pipeline Steels ◽  
Gtn Model ◽  
Input Parameters

Abstract The ability to arrest a running crack is one of the key features in the safe design of pipeline systems. In the industry design codes, the crack arrest properties of a pipeline should meet two requirements: crack propagation has to occur in a ductile fashion, and enough energy should be dissipated during propagation. While the first criterion is assessed by the Battelle Drop Weight Tear Test (BDWTT) at low temperatures, the latter requirement is converted into a lower bound for the impact energy absorbed during a Charpy V-notch (CVN) impact test. However, the introduction of high strength pipelines steels (X70 and beyond) has revealed that the commonly used relations based on BDWTT and CVN no longer hold. For such scenarios, Continuum Damage Mechanics (CDM) models provide promising potential to obtain a more profound understanding of the mechanisms that govern ductile crack propagation in high strength pipeline steels. In recent years, different types of CDM models have been used to simulate ductile fracture of pipeline steels. This paper focuses on two of these models, i.e. the Gurson-Tvergaard-Needleman (GTN) model and the Modified Bai-Wierzbicki (MBW) model. The GTN model is based on the computation of void growth according to Rice and Tracey, and account for the local softening of the material due to void nucleation, growth and subsequent coalescence. The MBW model is a fully coupled damage model, where the yield surface depends on both the stress triaxiality and the Lode angle. Although both models can predict ductile fracture propagation, their widespread application in pipeline design is hampered by the large number of input parameters to be calibrated. The GTN model requires 10 input parameters, i.e. 3 Tvergaard damage parameters, 4 porosity parameters and 3 parameters to describe void nucleation. Whereas the Modified Mohr-Coulomb model originally proposed by Bai and Wierzbicki uses merely 2 parameters, the extended MBW model requires no less than 18 parameters to be calibrated: 11 plasticity parameters (5 stress + 3 strain rate + 3 temperature) and 7 damage parameters (4 initiation + 1 propagation + 2 failure). In this paper, different numerical/experimental strategies to calibrate these parameter sets are reviewed and compared. Sensitivity analyses are performed to assess the influence of the different input parameters on the model predictions. For both GTN and MBW models, the robustness and uniqueness of the calibrated parameter sets is investigated. Recommendations on optimum parameter values are derived, with special emphasis on high strength pipeline steels.

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