Continuum Damage Mechanics and the Life-Fraction Rule

2005 ◽  
Vol 73 (4) ◽  
pp. 702-704 ◽  
Author(s):  
U. Stigh
Keyword(s):  
High Temperature ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Short Review ◽  
Necessary Condition ◽  
Continuum Damage ◽  
Evolution Law ◽  
Open Question ◽  
Life Fraction

This paper gives a short review of two different methods for life prediction at high temperature; namely continuum damage mechanics (CDM) and the linear life-fraction rule (LFR). It is well known that the class of CDM theories with a separable evolution law gives a life prediction in accordance with the LFR. However, it appears to be an open question if this is a necessary condition. It is here shown that in order for a CDM theory to comply with the LFR it must have a separable evolution law. That is, if we can assume that a material follows the LFR, it is necessary to chose a separable evolution law for this material. The reverse is also true, to get a life-fraction different from unity, we must chose a nonseparable evolution law.

Life Prediction of High Temperature Welded Component by Skeletal Point Rupture Stress

2010 ◽  
Vol 118-120 ◽  
pp. 156-160 ◽  
Author(s):  
Guo Dong Zhang ◽  
Yan Fen Zhao ◽  
Fei Xue ◽  
Zhao Xi Wang ◽  
Chang Yu Zhou
Keyword(s):  
High Temperature ◽  
Life Prediction ◽  
Power Plants ◽  
Damage Mechanics ◽  
Welded Joint ◽  
Stress Rupture ◽  
Continuum Damage Mechanics ◽  
Chemical Plants ◽  
Continuum Damage ◽  
Rupture Stress

At the present time, as the steam conditions and capability of the supercritical power unit increasing, the unit reliability is an important factor for the unit efficiency. High temperature, thick walled pipes are widely used in power plants and chemical plants. In this paper, life of the welded joint was predicted by the methods of skeletal point (SP) rupture stress rupture stress, which was calculated by finite element method (FEM). For the life prediction of welded component, the continuum damage mechanics was employed too. The life prediction of the welded joint by SP rupture stress was compared with the life prediction by the method of continuum damage mechanics (CDM). The research results showed that the two predicted methods were consistent. So, it can be concluded that the SP rupture stress can be used for predicting life of the high temperature welded component. The SP rupture stress method was used conveniently for the structure of power plant or other high temperature components.

Creep Life Prediction of Aircraft Turbine Disc Alloy Using Continuum Damage Mechanics

2017 ◽  
Vol 38 (1) ◽  
pp. 25-30
Author(s):  
Yan-Feng Li ◽  
Zhisheng Zhang ◽  
Chenglin Zhang ◽  
Jie Zhou ◽  
Hong-Zhong Huang
Keyword(s):  
Numerical Analysis ◽  
Test Data ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Creep Model ◽  
Continuum Damage ◽  
Creep Life ◽  
Creep Life Prediction ◽  
Turbine Disc

Abstract This paper deals with the creep characteristics of the aircraft turbine disc material of nickel-base superalloy GH4169 under high temperature. From the perspective of continuum damage mechanics, a new creep life prediction model is proposed to predict the creep life of metallic materials under both uniaxial and multiaxial stress states. The creep test data of GH4169 under different loading conditions are used to demonstrate the proposed model. Moreover, from the perspective of numerical simulation, the test data with analysis results obtained by using the finite element analysis based on Graham creep model is carried out for comparison. The results show that numerical analysis results are in good agreement with experimental data. By incorporating the numerical analysis and continuum damage mechanics, it provides an effective way to accurately describe the creep damage process of GH4169.

scholarly journals A Review on Fatigue Life Prediction Methods for Metals

2016 ◽  
Vol 2016 ◽  
pp. 1-26 ◽  
Author(s):  
E. Santecchia ◽  
A. M. S. Hamouda ◽  
F. Musharavati ◽  
E. Zalnezhad ◽  
M. Cabibbo ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Prediction Model ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Fatigue Life Prediction ◽  
Continuum Damage ◽  
Metallic Materials ◽  
Variable Amplitude Loading ◽  
Variable Amplitude

Metallic materials are extensively used in engineering structures and fatigue failure is one of the most common failure modes of metal structures. Fatigue phenomena occur when a material is subjected to fluctuating stresses and strains, which lead to failure due to damage accumulation. Different methods, including the Palmgren-Miner linear damage rule- (LDR-) based, multiaxial and variable amplitude loading, stochastic-based, energy-based, and continuum damage mechanics methods, forecast fatigue life. This paper reviews fatigue life prediction techniques for metallic materials. An ideal fatigue life prediction model should include the main features of those already established methods, and its implementation in simulation systems could help engineers and scientists in different applications. In conclusion, LDR-based, multiaxial and variable amplitude loading, stochastic-based, continuum damage mechanics, and energy-based methods are easy, realistic, microstructure dependent, well timed, and damage connected, respectively, for the ideal prediction model.

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