Cyclic plasticity behaviors of steam turbine rotor subjected to cyclic thermal and mechanical loads

Zhu, Xiaodong; Chen, Haofeng; Xuan, Fu‐Zhen; Chen, Xiaohui

doi:10.1016/j.euromechsol.2017.07.012

Cited by 25 publications

(14 citation statements)

References 22 publications

(19 reference statements)

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“…Chen et al have also proved its performance by presenting accurate limit loads and shakedown boundaries of a single 90° pipe bend [15]. In addition, the LMM has been utilised to analyse cyclic plasticity of various industrial structures including composite materials with or without creep effect [16][17][18][19]. Upon these reasons, the LMM is selected to use in this paper to analyse the limit, shakedown, and ratchet boundaries of the 90° back-to-back pipe bends.…”

Section: Iterative Elastic Techniques Are a Typical Approach Of Direcmentioning

confidence: 99%

Shakedown, ratchet, and limit analyses of 90° back-to-back pipe bends under cyclic in-plane opening bending and steady internal pressure

Cho

Chen

2018

European Journal of Mechanics - A/Solids

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A 90° back-to-back pipe bend structure subjected to cyclic in-plane bending moment and steady internal pressures is analysed by means of the Linear Matching Method (LMM) in order to create the limit, shakedown, and ratchet boundaries. The analyses performed in this work demonstrate that the cyclic moment has a more significant impact upon the structural integrity of the pipe bend than the constant pressure. Full cyclic incremental analyses are used to verify the structural responses either side of each boundary and confirm correct responses. In addition, the shakedown boundary produced by the LMM is compared to another shakedown boundary of an identical pipe bend computed by the simplified technique and it is shown that the LMM calculates results more accurately. Parametric studies involving a change of geometry of the pipe bends and loading type are carried out. From the studies of the geometry, two semi-empirical equations are derived from correlations of the reverse plasticity limit and the limit pressure with the bend characteristic. Finally, the results presented in this paper provide a comprehensive understanding of post-yield behaviours of the 90° back-to-back pipe structure under the combined loading as well as offering essential points to be concerned for the life assessment of the piping system.

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Section: Iterative Elastic Techniques Are a Typical Approach Of Direcmentioning

confidence: 99%

Shakedown, ratchet, and limit analyses of 90° back-to-back pipe bends under cyclic in-plane opening bending and steady internal pressure

Cho

Chen

2018

European Journal of Mechanics - A/Solids

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“…The numerical procedures to calculate shakedown and ratchet limit analysis have been introduced in extensive works [8,9], therefore full numerical procedures of the LMM are not presented in this paper. Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Iterative elastic technique is a typical approach which contains Elastic Compensation Method [4], GLOSS R-node method [5], LMM [6], and so on. The LMM has acquired distinguished reputation of providing accurate result for many complicated geometries subjected to complex loading as well as it can consider temperature dependent material parameters [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Cyclic Plasticity Behavior of 90° Back-to-Back Pipe Bends Under Cyclic Bending and Steady Pressure

Cho

Chen

2018

Volume 9: Student Paper Competition

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Back-to-back pipe bends are widely adopted applications in many industries including nuclear sectors. Evaluation of their load bearing capability under complex cyclic loading is very important. Recently, a couple of research reported shakedown boundary of a 90° back-to-back pipe bends by adopting a conservative approach but no comprehensive post yield structural behaviors have been dealt with. In this research the concerning pipe bends subjected to cyclic opening in-plane (IP)/out-of-plane (OP) bending and steady internal pressures are analyzed to construct shakedown and ratchet limit boundary by means of the Linear Matching Method. Analyzed results present that the concerning pipe bends under out-of-plane bending has higher resistance to cyclic bending than under in-plane bending. In additions, the out-of-plane bending causes very small alternating plasticity areas, unlike the in-plane bending. Full cyclic incremental analyses known as step-by-step analysis are performed to verify the structural responses either side of each boundary and confirm correct responses. Parametric studies are carried out with respect to changes in geometry of the concerning pipe bends subjected to the same loading, and semi-empirical equations are derived from relationships of the reverse plasticity limit and the limit pressure with the bend characteristic. This paper offers broad understandings of structural responses of the 90° back-to-back pipe bends under the complex cyclic loading as well as providing key points to be considered for the life assessment of the piping system.

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“…In the above-mentioned methods, the ideal blade shape is typically obtained by analyzing the aerodynamic performance according to the designed operating conditions. As steam turbines are operated under conditions such as high loading and high rotational speed, the blades are subjected to multiple complex loads, including centrifugal and aerodynamic loads [4,8,19,20].…”

Section: Introductionmentioning

confidence: 99%

Hot Blade Shape Reconstruction Considering Variable Stiffness and Unbalanced Load in a Steam Turbine

Zhou

Qiu

et al. 2020

Energies

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The blades in the low-pressure stage of a steam turbine must be reverse engineered according to the ideal blade shape due to the deformation of the blade during operation. A numerical analysis model of the flow field of the blades is proposed, and the model is solved by alternating between the fluid domain and the solid domain. Considering the imbalance of the load acting on the blade surface and the change in the blade stiffness matrix when the steam turbine is running, the Newton–Raphson method is used to calculate the pressure of the steam fluid on the blade surface and the change in the flow field caused by the blade deformation in each time step. The data are exchanged between the fluid domain and the solid domain after a single-step solution is completed. The simultaneous changes in the fluid domain and the solid domain are discretized in very short time steps, and the process of the blade deformation from stationary to running is simulated by accumulating the time steps. Finally, the trends in the change in the blade deformation and the aerodynamic load during the deformation process are analyzed according to the result of the reconstruction of the blade shape.

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Cyclic plasticity behaviors of steam turbine rotor subjected to cyclic thermal and mechanical loads

Cited by 25 publications

References 22 publications

Shakedown, ratchet, and limit analyses of 90° back-to-back pipe bends under cyclic in-plane opening bending and steady internal pressure

Shakedown, ratchet, and limit analyses of 90° back-to-back pipe bends under cyclic in-plane opening bending and steady internal pressure

Cyclic Plasticity Behavior of 90° Back-to-Back Pipe Bends Under Cyclic Bending and Steady Pressure

Hot Blade Shape Reconstruction Considering Variable Stiffness and Unbalanced Load in a Steam Turbine

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