A Practical Experiment and FEM Combined Method for Evaluation of Steam Turbine Diaphragm’s Creep Life

2014 ◽  
Author(s):  
C. Meng ◽  
J. H. Xin ◽  
C. Ye ◽  
H. Han
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Steam Turbine ◽  
Power Plants ◽  
Thermal Power ◽  
Element Model ◽  
Life Assessment ◽  
Creep Life ◽  
Creep Life Assessment ◽  
The Right

The security and stability of the steam turbine equipments are of great importance for thermal power plants. The diaphragm of steam turbine is usually tested as lack of stiffness due to creep deformation in the practical operation. In this paper, a creep life assessment of the diaphragm of a practical steam turbine was presented. The finite element model of the diaphragm was construed, and its accuracy was verified via a defection test. The classic Norton creep law was applied to the calculation process and its creep parameters were determined via iteration to obtain an appropriate value which would make the calculated deformation data equal to the practical experimental data. The creep life of the diaphragm was obtained based on the appropriate finite element model and the right creep parameters. The result shows that the method is an effect way in the engineering field to evaluate the creep life of components of steam turbine and gas turbine’s equipment in the situation that the material property is unknown.

Detailed Finite Element Modeling of a High Capacity Mooring Steel Wire Rope: Calculation of the Stress Concentration Near the Connection

2020 ◽  
Author(s):  
Michaël Martinez ◽  
Sébastien Montalvo
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Finite Element Model ◽  
Steel Wire ◽  
High Capacity ◽  
Element Model ◽  
Wire Rope ◽  
Contact Forces ◽  
Life Assessment

Abstract The mooring of floating platforms is an important challenge for the offshore industry. It is an important part of the design engineering and, often, a critical point for the fatigue life assessment. A solution that could improve the fatigue life is to directly connect the mooring rope to the platform, without an intermediate chain. However this solution is not widespread and the behavior of a rope near such a connection is little known. The present paper proposes to better understand this behavior, thanks to a detailed finite element model of the rope. The study case is a steel wire rope directly connected to a floating wind turbine. A local finite element model of the rope has been built, where the wires are individually modeled with beam elements. One end of the rope is clamped, simulating the connection, while tension and cyclic bending oscillations are applied to the other end. A localized bending takes place near the connection, leading to stress concentration in the wires. The stress concentration and the local contact forces are calculated for each wire. These data are important entry parameters for a local failure or fatigue analysis. This latter is however not presented here. Despite IFPEN experience in the development of local finite element models of steel wire ropes, it is the first time that such a high capacity rope (MBL = 12 500 kN) is modeled. This is challenging because of the large diameter of the rope and the large number of wires. However this modeling approach is very valuable for such ropes, because the experimental tests are rare and very expensive.

scholarly journals A Study on Fluid Self-Excited Flutter and Forced Response of Turbomachinery Rotor Blade

2014 ◽  
Vol 2014 ◽  
pp. 1-20 ◽  
Author(s):  
Chih-Neng Hsu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Power Plants ◽  
Single Mode ◽  
Element Model ◽  
Forced Response ◽  
Structural Dynamic ◽  
Turbine Engine ◽  
Forcing Function ◽  
Structural Dynamic Characteristics

Complex mode and single mode approach analyses are individually developed to predict blade flutter and forced response. These analyses provide a system approach for predicting potential aeroelastic problems of blades. The flow field properties of a blade are analyzed as aero input and combined with a finite element model to calculate the unsteady aero damping of the blade surface. Forcing function generators, including inlet and distortions, are provided to calculate the forced response of turbomachinery blading. The structural dynamic characteristics are obtained based on the blade mode shape obtained by using the finite element model. These approaches can provide turbine engine manufacturers, cogenerators, gas turbine generators, microturbine generators, and engine manufacturers with an analysis system to remedy existing flutter and forced response methods. The findings of this study can be widely applied to fans, compressors, energy turbine power plants, electricity, and cost saving analyses.

THE LIFE ASSESSMENT OF STEAM TURBINE ROTORS FOR FOSSIL POWER PLANTS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4371-4376
Author(s):  
SUNGHO CHANG ◽  
GEEWOOK SONG ◽  
BUMSHIN KIM ◽  
JUNGSEB HYUN ◽  
JEONGSOO HA
Keyword(s):  
Power Plant ◽  
Steam Turbine ◽  
Rotational Speed ◽  
Power Plants ◽  
Thermal Power ◽  
Creep Damage ◽  
Life Assessment ◽  
Life Extension ◽  
Start Up ◽  
Operational Life

The operational mode of thermal power plants has been changed from base load to duty cycle. From the changeover, fossil power plants cannot avoid frequent thermal transient states, for example, start up and stop, which results in thermal fatigue damage at the heavy section components. The rotor is the highest capital cost component in a steam turbine and requires long outage for replacing with a new one. For an optimized power plant operational life, inspection management of the rotor is necessary. It is known in general that the start-up and shutdown operations greatly affect the steam turbine life. The start-up operational condition is especially severe because of the rapid temperature and rotational speed increase, which causes damage and reduction of life of the main components life of the steam turbine. The start-up stress of a rotor which is directly related to life is composed of thermal and rotational stresses. The thermal stress is due to the variation of steam flow temperature and rotational stress is due to the rotational speed of the turbine. In this paper, the analysis method for the start-up stress of a rotor is proposed, which considers simultaneously temperature and rotational speed transition, and includes a case study regarding a 500MW fossil power plant steam turbine rotor. Also, the method of quantitative damage estimation for fatigue-creep damage to operational conditions, is described. The method can be applied to find weak points for fatigue-creep damage. Using the method, total life consumption can be obtained, and can be also be used for determining future operational modes and life extension of old fossil power units.

Effect of Steam Turbine Rotor Notch Fillet Radius on Stress and Deformation

2013 ◽  
Vol 860-863 ◽  
pp. 1770-1781
Author(s):  
Dong Mei Ji ◽  
M. H. Herman Shen ◽  
Shi Hua Yang ◽  
Gang Xia
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Finite Element Model ◽  
Steam Turbine ◽  
Element Model ◽  
Turbine Rotor ◽  
Critical Value ◽  
Steam Turbine Rotor ◽  
Fillet Radius ◽  
Start Up

A thorough investigation on the effect of a 320MW steam turbine rotor notch fillet radius on thermal and mechanical stresses during start up is presented. The approach consists of a shape design and analysis procedure which incorporates a finite element model. The finite element model is used to characterize the radius of the rotor notch fillet for ensuring the designed thermal and mechanical stress state/pattern and associated deflection during start-up. The results indicate that the notch fillet radius r has significant impact on the total stress of the rotor, in particular on thermal stress. It is determined that the thermal stress is decreased as the notch fillet radius r increases to a critical value. However, the thermal stress becomes saturated as the radius is increased to values larger than the critical value. The results also indicate that the rotor notch fillet radius has little effect on the deflection of the rotor during start-up. This investigation could be very useful to designers for construction of the design guidelines for steam turbine rotors.

Assessing Prestress Losses in a Nuclear Containment Structure for License Renewal

2019 ◽  
Author(s):  
Eric Kjolsing ◽  
Randy James ◽  
Keith Kubischta ◽  
Dan Parker
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Nuclear Power ◽  
Power Plants ◽  
Element Model ◽  
Paper Analysis ◽  
Design Parameters ◽  
Original Design ◽  
Structural Capacity ◽  
Post Tensioning

Abstract Nuclear power plants around the world are nearing the end of their designed service life. Sufficient structural capacity must be demonstrated to extend each plant’s operating license when accounting for concrete creep, shrinkage, and tendon relaxation past the original design life. This may take the form of in-situ values which meet the design allowable or, as outlined in this paper, analysis models which demonstrate capacity. This paper presents an analysis methodology for a concrete containment structure utilizing grouted post-tensioned tendons representative of a non-US design. The methodology is intended to demonstrate that a structure can still meet established design requirements while accounting for creep, shrinkage, and tendon relaxation. The analysis effort is performed in multiple stages. First, design parameters feeding into post-tensioning loss calculations are identified and assigned statistical distributions. Probabilistic estimates of the post-tensioning losses are developed using both a variational and Monte Carlo approach. Second, a finite element model of a representative containment structure is developed with tendons and reinforcement explicitly modeled. Lastly, the finite element model is used in example analyses to demonstrate future performance and pressure capacity accounting for projected tendon losses.

scholarly journals Numerical Simulation of Fatigue Performance of Diaphragm of Large-Span Bridge Orthotropic Deck

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-19
Author(s):  
Hui Li ◽  
Bo Zhao ◽  
Han Zhu
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Fatigue Life ◽  
Finite Element Model ◽  
Element Model ◽  
Life Assessment ◽  
Steel Bridge ◽  
Large Span ◽  
Finite Element Software ◽  
Fatigue Life Assessment

Under traffic loads, orthotropic steel bridge slabs suffer from an obvious fatigue problem. In particular, fatigue cracking of diaphragms seriously affects application and development of orthotropic bridge slabs. In the paper, based on cracking status quo of an orthotropic deck diaphragm of a large-span bridge, experimental tests were formulated to test stress distribution states of the diaphragm. The finite element software ABAQUS was used to establish a finite element model of the orthotropic deck diaphragm; numerical simulation was conducted on the basis of the experiments. Simulation results were compared with experimental results, so correctness of the finite element model was verified. Finally, Local Strain Approach (LSA) and Theory of Critical Distance (TCD) were used to conduct life assessment of the orthotropic deck diaphragms, and applicability of two methods was discussed. In this way, a fatigue life assessment method with high accuracy and good operability was provided for fatigue life assessment of orthotropic deck diaphragms.

Development of a Patient-Specific Nonlinear Finite Element Model for the Simulation of Lung Motion During Cancer Radiation Therapy

2009 ◽  
Author(s):  
Jaesung Eom ◽  
Chengyu Shi ◽  
George Xu ◽  
Suvranu De
Keyword(s):  
Finite Element ◽  
Radiation Therapy ◽  
Finite Element Model ◽  
Element Model ◽  
Nonlinear Finite Element ◽  
Patient Specific ◽  
Lung Motion ◽  
Ct Data ◽  
The Right ◽  
Nonlinear Finite Element Model

Respiratory motion causes either over-dose to the tumor or under-dose to the organ at risk in radiation therapy treatment for cancer. In order to characterize the motion, a nonlinear finite element model of the lungs has been developed based on 4D computed tomography (CT) data of a cancer patient with a tumor in the right lung. Pressure-volume (PV) curve data was applied to deform the model in real time. Realistic results are obtained when contact conditions are imposed between the pleura and the thoracic cavity.

The Effect of Impactor Location on the Validation of a Full Body Finite Element Model in Two Loading Cases

2012 ◽  
Author(s):  
Nicholas A. Vavalle ◽  
Daniel P. Moreno ◽  
Joel D. Stitzel ◽  
F. Scott Gayzik
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Complex Loading ◽  
Element Model ◽  
Sensitivity Study ◽  
Oblique Impact ◽  
Lateral Impact ◽  
Element Analysis ◽  
The Right ◽  
Full Body

Finite element analysis (FEA) is a tool used by many in the injury biomechanics field. FEA allows researchers to study the stresses and strains in complex loading scenarios that would be impossible to determine experimentally. A vital step toward ensuring accurate results is validation of the finite element model (FEM), which is often based on matching model results to experimental results. While care is taken in performing experiments, there are still sources of variance in empirical results like experimental error and cadaver variation. In order to mimic these, location variations of two validation cases were studied, an oblique impact to the right thoracoabdominal region and a lateral impact to the right shoulder. Five locations were studied for each case, the nominal and four variations. The object of this study was to determine model robustness, conduct a sensitivity study of the model, and to simulate experimental subject variation without the use of subject-specific models. This study utilizes the Global Human Body Models Consortium (GHBMC) midsized male model. The model reflects a global effort to develop a set of state-of-the-art full body finite element models.

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