Parametric Studies on Bolted Flange Thermal Analysis to Improve LCF Life

2013 ◽  
Author(s):  
Mohd. Yousuf ◽  
Krishna Nelanti ◽  
Rajendra Prasad Allabanda
Keyword(s):  
Thermal Analysis ◽  
Life Stress ◽  
Low Cycle Fatigue ◽  
Aircraft Engine ◽  
Bolted Joints ◽  
Thermal Gradients ◽  
Flange Thickness ◽  
Parametric Studies ◽  
Bolted Flange ◽  
The Impact

Low cycle fatigue (LCF) life plays an important role in the design of aircraft engine components, especially that of bolted joints. Bolted joints are of critical importance in aircraft engines as they connect parts and transfer loads. In gas turbine engines, most of the bolted flanges experience high pressure loads & high thermal gradients. LCF life/stress is very sensitive to the thermal gradients encountered in flight cycle (from idle to takeoff & takeoff to landing). Accurate flange leakage modeling & accurate boundary condition estimation are critical to design. This paper emphasizes on thermal analysis of bolted flange using the finite element method. Thermal analysis results show that, during flight cycle (Accel/Decel), flange leakage is a key contributor to thermal gradients. The flange leakage is majorly influenced by the gap between the flanges. Parametric studies have been carried out to understand the impact of gap between the flanges, flange thickness and flange height on the flange thermal gradients. The results presented in this paper will be helpful to the designer in designing better bolted flange joints with improved LCF life.

scholarly journals High Temperature Testing and Analysis of a Class 300 Bolted Flange Joint

2014 ◽  
Author(s):  
J. Adin Mann ◽  
Jeremy Hilsabeck ◽  
Cale Mckoon
Keyword(s):  
High Temperature ◽  
Bolted Joints ◽  
Flange Joint ◽  
Simulation Approach ◽  
High Temperature Testing ◽  
Material Creep ◽  
Fea Simulation ◽  
Bolted Flange ◽  
The Impact

When class 300 flange bolted joints are held at temperatures in the material creep range, it is documented that the bolt loads can relax. Tests and analysis are being performed with the goal of developing a validated FEA simulation approach to predicting the impact of creep on the bolt loads. The bolt load and gasket geometry are evaluated upon bolt up and after being heated to 1100 deg F. Tests are performed with and without a gasket to separate the impact of the gasket relaxation and flange material creep. The results of the tests and analysis approaches will be presented. Paper published with permission.

Assessment of the Influence of Bulging and the Thermal Gradients in the Stress Level in the Cylindrical Section of a Coke Drum

2013 ◽  
Author(s):  
Egler D. Araque ◽  
Gabriel A. Vivas
Keyword(s):  
Thermal Analysis ◽  
Low Cycle Fatigue ◽  
Mechanical Analysis ◽  
Second Step ◽  
Thermal Gradients ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Part D ◽  
Cylindrical Section ◽  
Made In

Several studies recognized that cracks in delayed coke drums resulted from low cycle fatigue induced by cyclic thermal stress [1], [2], [3]. According to a coke drum survey coordinated by API in 1996 [1], there are two different areas where cracks are produced. The first zone is located at the shell to skirt weld, and the second at the bulging areas found in the cylindrical section. In the second case, from 145 coke drums 57% reported that had shell bulging problems. Of the drums that bulged, 87% also showed cracks. In order to estimate the level of stress, finite element analysis of a bulged cylinder was performed. The study was carried out running a sequentially-coupled thermo-mechanical analysis. In the first step, a thermal analysis is used to estimate the variation of temperature with time. These temperatures serve as input to a mechanical stress analysis that was made in a second step. The assessment shows the influence of thermal gradients obtained for a period of 26 months for several bulging patterns that were identified from the analysis of 28 laser mappings of coke drums. The results indicated that the level of stress could reach the plastic deformation considering that the material has yield strength equal to the minimum specified in ASME Section II, part D. The zones where maximum axial stresses were found are consistent with areas where cracking has been reported in many coke drums.

Quantification of the Impact of Strontium on the Solidification Path of the Aluminum-Silicon-Copper Alloys Using Thermal Analysis Technique

2009 ◽  
Vol 46 (3) ◽  
pp. 137-152 ◽  
Author(s):  
Mile Djurdjevic ◽  
Glenn Byczynski ◽  
Carola Schechowiak ◽  
Hagen Stieler ◽  
Jelena Pavlovic
Keyword(s):  
Thermal Analysis ◽  
Copper Alloys ◽  
Solidification Path ◽  
Thermal Analysis Technique ◽  
Analysis Technique ◽  
The Impact ◽  
Aluminum Silicon

scholarly journals Deep Neural Network and Polynomial Chaos Expansion-Based Surrogate Models for Sensitivity and Uncertainty Propagation: An Application to a Rockfill Dam

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1830
Author(s):  
Gullnaz Shahzadi ◽  
Azzeddine Soulaïmani
Keyword(s):  
Polynomial Chaos ◽  
Complex Structure ◽  
Uncertainty Propagation ◽  
Surrogate Models ◽  
Polynomial Chaos Expansion ◽  
Soil Parameters ◽  
Chaos Expansion ◽  
Rockfill Dam ◽  
Parametric Studies ◽  
The Impact

Computational modeling plays a significant role in the design of rockfill dams. Various constitutive soil parameters are used to design such models, which often involve high uncertainties due to the complex structure of rockfill dams comprising various zones of different soil parameters. This study performs an uncertainty analysis and a global sensitivity analysis to assess the effect of constitutive soil parameters on the behavior of a rockfill dam. A Finite Element code (Plaxis) is utilized for the structure analysis. A database of the computed displacements at inclinometers installed in the dam is generated and compared to in situ measurements. Surrogate models are significant tools for approximating the relationship between input soil parameters and displacements and thereby reducing the computational costs of parametric studies. Polynomial chaos expansion and deep neural networks are used to build surrogate models to compute the Sobol indices required to identify the impact of soil parameters on dam behavior.

Comparison Between Two-Shaft Simple and Single-Shaft Recuperated Brayton Cycles Using Different Types of Gaseous Fuels

2010 ◽  
Author(s):  
A. K. Malkogianni ◽  
A. Tourlidakis ◽  
A. L. Polyzakis
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Alternative Fuels ◽  
High Efficiency ◽  
Heating Value ◽  
Gaseous Fuels ◽  
Oil And Natural Gas ◽  
Parametric Studies ◽  
The Impact ◽  
Lower Heating

Geopolitical issues give rise to problems in the smooth and continuous flow of oil and natural gas from the production countries to the consumers’ development countries. In addition, severe environmental issues such as greenhouse gas emissions, eventually guide the consumers to fuels more suitable to the present situation. Alternative fuels such as biogas and coal gas have recently become more attractive because of their benefits, especially for electricity generation. On the other hand, the use of relatively low heating value fuels has a significant effect to the performance parameters of gas turbines. In this paper, the impact of using four fuels with different heating value in the gas turbine performance is simulated. Based on the high efficiency and commercialization criteria, two types of engines are chosen to be simulated: two-shaft simple and single-shaft recuperated cycle gas turbines. The heating values of the four gases investigated, correspond to natural gas and to a series of three gases with gradually lower heating values than that of natural gas. The main conclusions drawn from this design point (DP) and off-design (OD) analysis is that, for a given TET, efficiency increases for both engines when gases with low heating value are used. On the contrary, when power output is kept constant, the use of gases with low heating value will result in a decrease of thermal efficiency. A number of parametric studies are carried out and the effect of operating parameters on performance is assessed. The analysis is performed with customized software, which has been developed for this purpose.

Thermomechanical Fatigue Behavior of Bare and Coated CMSX-4

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
T. Coppola ◽  
S. Riscifuli ◽  
O. Tassa ◽  
G. Pasquero
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Thermomechanical Fatigue ◽  
Tensile Creep ◽  
Thermal Gradients ◽  
Test Program ◽  
Complete Set ◽  
Comparison Of The Results ◽  
Very High

Highly cooled turbine blades undergo very high thermal gradients during rapid engine idle-max-idle cycling. Traditional isothermal fatigue data are often insufficient for predicting service lives. A complete set of high temperature tests, in the range of 750–1050°C, was performed on single crystal alloy CMSX-4. The test program comprised tensile, creep, low cycle fatigue, and thermomechanical fatigue (TMF) tests. In particular the cycle time for TMF was 3 min, aiming to simulate the real high-power transient conditions in aircraft engines. Clockwise and counterclockwise diamond cycle types were applied on bare and coated specimens to investigate their influence on the fatigue limit. The comparison of the results obtained with the available ones from open literature is discussed.

scholarly journals Correction: N-3 Polyunsaturated Fatty Acids (PUFAs) Reverse the Impact of Early-Life Stress on the Gut Microbiota

PLoS ONE ◽  
2015 ◽  
Vol 10 (10) ◽  
pp. e0142228 ◽  
Author(s):  
Matteo M. Pusceddu ◽  
Sahar El Aidy ◽  
Fiona Crispie ◽  
Orla O’Sullivan ◽  
Paul Cotter ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Gut Microbiota ◽  
Polyunsaturated Fatty Acids ◽  
Life Stress ◽  
Early Life ◽  
Early Life Stress ◽  
The Impact

Passenger aircraft emissions analysis at Ordu-Giresun International Airport, Turkey in 2017

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ilkay Orhan
Keyword(s):  
Aircraft Engine ◽  
Civil Aviation ◽  
Exhaust Emission ◽  
Aircraft Emissions ◽  
Emission Data ◽  
Emission Analysis ◽  
Content Type ◽  
International Airport ◽  
Engine Emission ◽  
The Impact

Purpose The purpose of this study is to present the pollutant gas produced by hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) and the quantity of fuel burned from commercial aircraft at Ordu-Giresun International Airport, Turkey during the landing and take-off (LTO) cycles in 2017. Design/methodology/approach The flight data recorded by the General Directorate of State Airports Authority and the aircraft engine emission data from International Civil Aviation Organization (ICAO) Engine Exhaust Emission Databank were used for calculation. The aircraft and engine types used by the airlines for flight at Ordu-Giresun International Airport were determined. To evaluate the effect of taxi time on emission amounts, analysis and evaluations were made by taking different taxi times into consideration. Findings As a result of the emission analysis, the amount of fuel consumed by the aircraft were calculated as 6,551.52 t/y, and the emission amounts for CO, HC and NOx were estimated as 66.81, 4.20 and 79.97 t/y, respectively. Practical implications This study is aimed to reveal the effect and contribution of taxi time on the emitted emission at the airport during the LTO phase of the aircraft. Originality/value This study helps aviation authorities explain the importance of developing procedures that ensure the delivery of aircraft to flights in minimum time by raising awareness of the impact of taxi time on emitted emissions, and contributes to the determination of an aircraft emission inventory at Ordu-Giresun International Airport.

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