Continuum Damage Mechanics Application in Low Cycle Fatigue Damage Assessment for Steam Turbine

2018 ◽  
Author(s):  
Yongjian Sun ◽  
Xiaohong Wang
Keyword(s):  
Steam Turbine ◽  
Fatigue Damage ◽  
Damage Assessment ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Cycle Fatigue

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.

Low Cycle Fatigue Study for GH901 Material Based on Damage Mechanics Theory

2014 ◽  
Vol 711 ◽  
pp. 40-43 ◽  
Author(s):  
Yong Qi Wang ◽  
Hai Bing Zhang
Keyword(s):  
Fatigue Damage ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Continuum Damage Mechanics ◽  
Practical Method ◽  
Test Results ◽  
Cycle Fatigue ◽  
Mechanics Model

The low cycle fatigue damage of turbine disc which is made of GH901 material is systematic analyzed and studied in the article that is based on the theory of continuum damage mechanics and fatigue testing, we improved the common Lemaitre’s low cycle fatigue damage mechanics model, the damage evolution law that the model describes is in good agreement with the test results throughout the course of the fatigue damage. The simplified analysis method for low cycle fatigue damage evolution and life prediction is proposed based on the GH901 low cycle damage features, the practical method of getting damaged material’s constants by existing data is proposed as well.

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.

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