Improving the Transient Thermal Fatigue Life of a Gas Turbine Casing by Drilling Stop Holes and Inserting Pins into Them (original) (raw)

Thermo-mechanical Analysis of Gas Turbine Casing to Enhance Fatigue Life

Modelling, Measurement and Control B

The vulnerability of gas turbine casings is the area which are found to be the geometries featuring sudden or abrupt changes, such as holes and cross sections. Thermal and mechanical fatigue, which is being exerted on the casing by virtue of factors such as mechanical vibration, thermal cyclic loads and mechanical loads, the fatigue life cycle of the casing is on stake. At the same time, fatigue life of casing is also influenced by the tension exerted by the bolt during assembly called "bolt pre-tension". This work is aimed to address the effect of bolt pre-tension on fatigue life of gas turbine casing taking accountability of its impact. The existing casing is analysed for impact of parameters such as pressure, bolt pre-tension and deformation and is being coupled with thermal boundary conditions and the model is analysed in ANSYS workbench. Based on the results of existing design, casing had to be modified geometrically so that its fatigue life is enhanced. From the analysis, it was found that the fatigue life of modified casing was 16533 cycles more than the fatigue life of existing casing for the same boundary conditions of bolt pre-tension of 1000 N and pressure of 3 MPa.

Effect of additional holes on crack propagation and arrest in gas turbine casing

Engineering Failure Analysis, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Experimental Methods for Thermomechanical Fatigue in Gas Turbine Materials

In order to improve life prediction models the understanding of the physical mechanisms active during various types of fatigue cycle conditions have to be understood. To that end, in-situ observations in an environmental scanning electron microscope have been performed. To produce the thermo-mechanical fatigue (TMF) cycle, a test equipment have been developed able to provide thermal cycles up to 900°C. An experimental series to analyze the differences between TMF in-phase and out-of-phase mechanical loading with respect to the temperature cycles has been performed of Inconel 718. Three different fatigue experiments, in-phase with temperature cycle 300-550°C, out-of-phase with temperature cycle 300-550°C and out-of-phase with temperature cycle 300-625°C, have been performed. Generally it was found that the fastest crack growth rate was obtained for in-phase loading. The choice of temperature in the out-of-phase type of cycling did not influence the crack propagation rate significantl...

ANALYSIS & MODELLING OF THERMAL MECHANICAL FATIGUE CRACK PROPAGATION OF TURBINE BLADE STRUCTURE

The main aim of this work to assessment for damage tolerance of framework by using computational mechanics software. The work is presented through this methodology simulating cracks gradation in the surface of texture of the walls of turbine blade. A study model the 2D ANSYS auxiliary thermal/structural model was created to facilitate sensitivity study. Geometry derived a model was used for finite elements model and Crack simulation have been computed. The analysis was made under combined loads of thermal and mechanical loads. The present data were taken from typical turbine blade used to run a heat transfer analysis and study of thermal structural analysis. Final result got through the analysis of thermal structural fracture mechanics. The interact between thermal and mechanical loads acting on the framework at a specified place structural reaction to approach the crack extremely is accounted for by employing a structure sub modelling and interpolation tactics. Factor of stress intensity are calculated using expansion of the M-integral method by the embed in France 3D/NG. Crack trajectories are resolute by applying the maxima stress principle. Crack augmentation result in on specified place is mesh of special element and destructive region are treatment automatically applicable developed all quadrilateral meshing algorithm the forecasted custom fatigue crack propagation results of the proposed methodology compares well with published in field of observation of failed blades. The effectiveness of the methodology and its applicability to execution practical analysis of actual structure is demonstrated by simulating curvilinear crack augmentation in a airfoil wall from cooling hole, which represent a typical turbine blade micro feature, at last a effected tolerance design methodology is proposed, where the effects of thermal mechanical fatigue are based on the combined respond the both un cracked and cracked blade geometry, the advantage of INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET) ISSN 0976 – 6340 (Print) ISSN 0976 – 6359 (Online) Volume 4, Issue 3, May - June (2013), pp. 155-176 © IAEME: www.iaeme.com/ijmet.asp Journal Impact Factor (2013): 5.7731 (Calculated by GISI) www.jifactor.com IJMET © I A E M E International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 3, May - June (2013) © IAEME 156 according to plans methodology are that if can accurately and parametrically of vary different input (complex model geometry, temperature gradient and material properties) to show the impact on the stress and strain as well as crack behaviour. The expected results can be estimate intensity of effects depends upon turbine engine condition and its specification

Thermal fatigue analysis on cracked plenum barrier plate of open-cycle gas turbine frame

Engineering Failure Analysis, 2010

Failure investigation is carried out following repeating findings of several obvious surfacecrack spots on the weld joint zone of a plenum barrier plate of open-cycle gas turbine frame. The exhausted hot compressed air will flow through the cracks entering the load compartment which contains temperature sensitive instrumentations and shaft bearings. The modified model of the barrier plate is presented for redesign consideration. Visual inspection, microscopic examination on the cracked barrier plate and thermal fatigue analyses based on strain-life approach are carried out. The life expectancies of the original and modified models for the barrier plate design are evaluated. The finding indicates that the modified model could withstand against the thermal fatigue longer than that of the original model.

Prediction of fatigue crack propagation lives of turbine discs with forging-induced initial cracks

Engineering Fracture Mechanics, 2014

This paper presents a study on residual life assessment of turbine discs in a military aircraft engine that were found to be susceptible to fatigue cracking failure due to forging flaws formed in the original manufacturing process. As these flaws were not considered in the original life assessment, it is important to predict the residual lives of affected turbine discs and to determine the safe inspection intervals in order to prevent possible failures during service. The examination of the cracked disc revealed that the flaw was formed during the hammer forging. A systematic analysis approach was developed to analyse all four turbine discs and to predict the fatigue crack growth (FCG) rates by using advanced finite element (FE) and numerical FCG predictions. The critical locations for these discs were found to be on the aft neck face of disc web. The predicted FCG for the cracked disc correlated reasonably well with the striation counting from the cracked disc. The residual lives for representative discs at the critical location and associated inspection intervals are determined for life management of the affected turbine discs.

ANALYSIS & MODELLING OF THERMAL MECHANICAL FATIGUE CRACK PROPAGAT.pdf

The main aim of this work to assessment for damage tolerance of framework by using computational mechanics software. The work is presented through this methodology simulating cracks gradation in the surface of texture of the walls of turbine blade. A study model the 2D ANSYS auxiliary thermal/structural model was created to facilitate sensitivity study. Geometry derived a model was used for finite elements model and Crack simulation have been computed. The analysis was made under combined loads of thermal and mechanical loads. The present data were taken from typical turbine blade used to run a heat transfer analysis and study of thermal structural analysis. Final result got through the analysis of thermal structural fracture mechanics. The interact between thermal and mechanical loads acting on the framework at a specified place structural reaction to approach the crack extremely is accounted for by employing a structure sub modelling and interpolation tactics. Factor of stress intensity are calculated using expansion of the M-integral method by the embed in France 3D/NG. Crack trajectories are resolute by applying the maxima stress principle. Crack augmentation result in on specified place is mesh of special element and destructive region are treatment automatically applicable developed all quadrilateral meshing algorithm the forecasted custom fatigue crack propagation results of the proposed methodology compares well with published in field of observation of failed blades. The effectiveness of the methodology and its applicability to execution practical analysis of actual structure is demonstrated by simulating curvilinear crack augmentation in a airfoil wall from cooling hole, which represent a typical turbine blade micro feature, at last a effected tolerance design methodology is proposed, where the effects of thermal mechanical fatigue are based on the combined respond the both un cracked and cracked blade geometry, the advantage of according to plans methodology are that if can accurately and parametrically of vary different input (complex model geometry, temperature gradient and material properties) to show the impact on the stress and strain as well as crack behaviour. The expected results can be estimate intensity of effects depends upon turbine engine condition and its specification.

Computer simulation of fatigue, creep and thermal-fatigue cracks propagation in gas-turbine blades

2012

Methods and computational algorithms for determining the growth rate of fatigue creep and thermal-fatigue cracks are considered. The rate of crack growth is dependent on the stress-intensity factor (or J-integral) for fatigue, on the C*-integral for creep and on the stress-intensity factor (or J-integral) and C*-integral for thermal fatigue. Simulations of the crack propagation under fatigue, creep and thermal fatigue at the edge of the blade of a gas turbine are carried out and discussed.

LCF Initiated - HCF Propagated Crack Life Estimation of Gas Turbine Bolts

2018

This paper discusses the methodology to calculate high cycle fatigue (HCF) crack propagation life of gas turbine bolts and compares two dimensional (2D) HCF crack propagation life to three dimensional (3D) HCF crack propagation life. Gas turbine bolts when exposed to fatigue loading are prone to crack initiation and propagation (structural failure) during operation. In such cases cracks mostly are initiated by low cycle fatigue (LCF) and propagated by HCF. Therefore in current illustration the authors have evaluated crack propagation primarily initiated by low cycle fatigue and propagated by high cycle fatigue. 2D and 3D fracture methodology approaches had been used for analytical evaluation. The authors conclude on the efficacy of both the methods based on the data from the field. The coupling joint bolts located in the engine mid-section, which are used to join compressor rotor with turbine rotor are being considered for crack evaluation studies. The coupling bolts located in mids...