Application of continuum damage mechanics model in terms of fatigue life assessment for low cycle and quasi static loadings

In this article, a fatigue model for low-cycle thermal fatigue formulated in a continuum damage mechanics framework is presented. The model is based on a unified damage law presented by Lemaitre for low-cycle fatigue, which has been extended to low-cycle thermal fatigue. The temperature dependencies of material parameters are considered in the damage evolution integration to take the non-isothermal condition of loading into account. This model considers the stress triaxiality and non-linearity of damage evolution, and it is developed to a fatigue damage accumulation rule in which the load sequence effect is also included. The stabilized structural response under thermomechanical loading motivates the use of uncoupled analysis approach making the model a fast tool suitable for design purposes in the costly and time-consuming field of thermomechanical fatigue life assessment. To demonstrate the capability and ease of use of this model for real industrial applications, the low-cycle thermal fatigue life of a stainless steel engine exhaust manifold which is in an early stage of design is assessed.

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A Continuum Damage Mechanics Model on Creep Rupture Life Assessment of a Steam Turbine Rotor

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.1924483 ◽

2005 ◽

Vol 128 (1) ◽

pp. 173-177 ◽

Cited By ~ 7

Author(s):

Jing JianPing ◽

Meng Guang ◽

Sun Yi ◽

Xia SongBo

Keyword(s):

Steam Turbine ◽

Damage Mechanics ◽

Continuum Damage Mechanics ◽

Turbine Rotor ◽

Life Assessment ◽

Continuum Damage ◽

Creep Life ◽

Steam Turbine Rotor ◽

Mechanics Model ◽

Nonlinear Continuum

A nonlinear continuum damage mechanics model is proposed to assess the high temperature creep life of a steam turbine rotor, in which the effect of mean stress is taken into account and the damage is accumulated nonlinearly. The model is applied to a 300 MW steam turbine under hot start operation. The results are compared with those from the linear accumulation theory that is dominant in the creep life assessment of steam turbine rotors at present. The comparison results show that the nonlinear continuum damage mechanics model describes the accumulation and development of damage better than the linear accumulation theory.

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Fatigue Life of the Human Teeth: A Continuum Damage Approach

Journal of Biomimetics Biomaterials and Biomedical Engineering ◽

10.4028/www.scientific.net/jbbbe.43.1 ◽

2019 ◽

Vol 43 ◽

pp. 1-19

Author(s):

Theddeus Tochukwu Akano

Keyword(s):

Fatigue Life ◽

Damage Mechanics ◽

Stress Amplitude ◽

Continuum Damage Mechanics ◽

Continuum Damage ◽

Elastoplastic Model ◽

Human Teeth ◽

Proposed Model ◽

Number Of Cycles ◽

Cycles To Failure

Normal oral food ingestion processes such as mastication would not have been possible without the teeth. The human teeth are subjected to many cyclic loadings per day. This, in turn, exerts forces on the teeth just like an engineering material undergoing the same cyclic loading. Over a period, there will be the creation of microcracks on the teeth that might not be visible ab initio. The constant formation of these microcracks weakens the teeth structure and foundation that result in its fracture. Therefore, the need to predict the fatigue life for human teeth is essential. In this paper, a continuum damage mechanics (CDM) based model is employed to evaluate the fatigue life of the human teeth. The material characteristic of the teeth is captured within the framework of the elastoplastic model. By applying the damage evolution equivalence, a mathematical formula is developed that describes the fatigue life in terms of the stress amplitude. Existing experimental data served as a guide as to the completeness of the proposed model. Results as a function of age and tubule orientation are presented. The outcomes produced by the current study have substantial agreement with the experimental results when plotted on the same axes. There is a notable difference in the number of cycles to failure as the tubule orientation increases. It is also revealed that the developed model could forecast for any tubule orientation and be adopted for both young and old teeth.

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