Incorporating Micro-Thermo-Mechanical Damage Model in Life Prediction Analysis of a Turbine Engine Blade to Disk Attachment

2013 ◽  
Author(s):  
Sam Naboulsi
Keyword(s):  
Damage Model ◽  
Mechanical Damage ◽  
Local Stress ◽  
Fretting Fatigue ◽  
Relative Displacement ◽  
Turbine Engine ◽  
Damage Initiation ◽  
Micro Scale ◽  
Damage And Failure ◽  
Initiation And Propagation

Fretting is an important problem for the operators of turbine engines, and it occurs when the blade and disk are pressed together in contact and experience a small oscillating relative displacement due to variations in engine speed and vibratory loading. It is a significant driver of fatigue damage and failure risk of disks. The present effort focuses on the damage initiation and propagation due to fretting fatigue. It introduces a micro-thermo-mechanical damage model that is capable of capturing the micro-scale nature of the fretting small oscillatory relative displacement. The micro-scale capability of the damage model is required to capture the effect of very high local stress near the edge of contact, which results in wear, nucleation of cracks, and their growth. It also provides a high fidelity approach to capture the significant reduction in the life of the material at the blade to disk attachment. To further understand the role of damage in the fretting initiated fracture, a specially developed novel fretting crack initiation model is incorporated in the analysis. Such combination makes it possible to simulate the realistic mechanism associated with fretting. The models are incorporated in a fretting fatigue simulation of an actual blade and disk attachment configuration. The results are validated with data obtained from an actual blade and disk attachment test using a representative loading mission. The results show consistency and accuracy with experimental data.

A Crystallographic Approach to Life Prediction Analysis of a Turbine Engine Blade to Disk Attachment

2014 ◽  
Author(s):  
Sam Naboulsi
Keyword(s):  
Local Stress ◽  
Fretting Fatigue ◽  
Relative Displacement ◽  
Orientation Dependence ◽  
Constitutive Law ◽  
Turbine Engine ◽  
Damage Initiation ◽  
Damage And Failure ◽  
Engine Blade ◽  
Individual Grains

Fretting fatigue raises many challenges in modeling and predicting of a turbine engine blade disk attachment response. It occurs when the blade and disk are pressed together in contact and experience a small oscillating relative displacement due to variations in engine speed and vibratory loading. Fretting causes a very high local stress near the edge of contact resulting in wear, nucleation of cracks, and their growth, which can result in significant reduction in the life of the material. Fretting depends on geometry, loading conditions, residual stresses, nonlinear response, and surface roughness, among other factors. These complexities make fretting a significant driver of fatigue damage and failure risk of disks. That is, fretting is often the root cause of the nucleation of cracks at attachments of structural components, and the cyclic plastic cumulative deformation and damage occur within depths of only several grains. Hence, resolving the deformation at the scale of individual grains, in order to understand the crystallographic orientation dependence of plasticity driven fretting fatigue and its relation to surface contact conditions, is important. In this study, a finite strain computational crystal plasticity constitutive law will be implemented to simulate and investigate time dependent response of turbine engine blade to disk attachment. The present work leverages the computational model of early efforts, which focused on modeling damage initiation and propagation due to fretting fatigue using micro-thermo-mechanical model, and further enhances the capabilities of capturing the micro-scale nature of the fretting small oscillatory relative displacement at grain level. These efforts provided a high fidelity approach to capture the life of the material at the blade to disk attachment and to simulate the realistic mechanism associated with fretting.

Life Prediction of a Turbine Engine Blade to Disk Attachment Under Coupled Thermo-Mechanical Fatigue

2017 ◽  
Author(s):  
Sam Naboulsi
Keyword(s):  
Fatigue Damage ◽  
Life Prediction ◽  
Damage Model ◽  
Thermal Conditions ◽  
Fretting Fatigue ◽  
Relative Displacement ◽  
Computational Domain ◽  
Engine Operation ◽  
Turbine Engine ◽  
Damage And Failure

Life prediction of turbine engines is crucial part of the management and sustainment plan to aircraft jet engine. Fretting is one of the primary phenomena that leads to damage or failure of blade-disk attachments. Fretting is often the root cause of nucleation of cracks at attachment of structural components at or in the vicinity of the contact surfaces. It occurs when the blade and disk are pressed together in contact and experience a small oscillating relative displacement due to variations in engine speed and vibratory loading. It is a significant driver of fatigue damage and failure risk of disk blade attachments. Fretting is a complex phenomenon that depends on geometry, loading conditions, residual stresses, and surface roughness, among other factors. These complexities also go beyond the physics of material interactions and into the computational domain. This is an ongoing effort, and the Author has been working on computationally modeling the fretting fatigue phenomenon and damage in blade-disk attachment. The model has been evolving in the past few years, and it has been addressing various fretting conditions. The present effort includes the thermal effect and temperature fluctuation during engine operation, and it models the effects of blade to disk attachment’s thermal conditions and its influence on fretting fatigue damage. It further extends the earlier model to include a coupled fatigue damage model. It allows modeling higher speeds and longer durability associated with blade disk attachments. Finally, to demonstrate its capabilities and taking advantage of experimental validation model, the most recent numerical simulations will be presented.

The Fatigue Behaviour of a High Strength CrNi-Steel Regarding Fretting Fatigue

2012 ◽  
Author(s):  
Thomas Christiner ◽  
Johannes Reiser ◽  
István Gódor ◽  
Wilfried Eichlseder ◽  
Franz Trieb ◽  
...  
Keyword(s):  
High Strength ◽  
Contact Problems ◽  
Fatigue Behaviour ◽  
Fretting Fatigue ◽  
Service Performance ◽  
Fatigue Properties ◽  
Material Behaviour ◽  
Reliable Prediction ◽  
Damage And Failure ◽  
Lubrication Conditions

In many assemblies of moving components, contact problems under various lubrication conditions are lifetime-limiting. There, relative motion of contacting bodies, combined with high loads transmitted via the contact surface lead to fretting fatigue failure. For a reliable prediction of in service performance load type, different damage and failure mechanisms that may be activated during operation have to be known. In this contribution selected results of a currently conducted research project are presented. The aim of this study was to examine the material behaviour of a surface stressed steel. The influence of the fretting regime on fatigue properties has been investigated.

Simple Instrumentation Rake Designs for Gas Turbine Engine Testing

1996 ◽  
Author(s):  
Peter D. Smout ◽  
Steven C. Cook
Keyword(s):  
Gas Turbine ◽  
Mechanical Damage ◽  
Engine Performance ◽  
Leading Edge ◽  
Gas Turbine Engine ◽  
Calibration Data ◽  
Turbine Engine ◽  
Industry Standard ◽  
Repair Costs ◽  
Engine Testing

The determination of gas turbine engine performance relies heavily on intrusive rakes of pilot tubes and thermocouples for gas path pressure and temperature measurement. For over forty years, Kiel-shrouds mounted on the rake body leading edge have been used as the industry standard to de-sensitise the instrument to variations in flow incidence and velocity. This results in a complex rake design which is expensive to manufacture, susceptible to mechanical damage, and difficult to repair. This paper describes an exercise aimed at radically reducing rake manufacture and repair costs. A novel ’common cavity rake’ (CCR) design is presented where the pressure and/or temperature sensors are housed in a single slot let into the rake leading edge. Aerodynamic calibration data is included to show that the performance of the CCR design under uniform flow conditions and in an imposed total pressure gradient is equivalent to that of a conventional Kiel-shrouded rake.

A Rational Methodology for Determination of Service Life for a Delayed Coker Drum

2015 ◽  
Author(s):  
John J. Aumuller ◽  
Jie Chen ◽  
Vincent A. Carucci
Keyword(s):  
Service Life ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Mechanical Damage ◽  
Damage Mechanism ◽  
Modern Trend ◽  
Cold Spot ◽  
Chromium Alloy ◽  
Cycle Fatigue ◽  
Service Environment

Delayed unit coker drums operate in a severe service environment that precludes long term reliability due to excessive shell bulging and cracking of shell joint and shell to skirt welds. Thermal fatigue is recognized as the leading damage mechanism and past work has provided an idealized description of the thermo-mechanical mechanism via local hot and cold spot formation to quantify a lower bound life estimate for shell weld failure. The present work extends this idealized thermo-mechanical damage model by evaluating actual field data to determine a potential upper bound life estimate. This assessment also provides insight into practical techniques for equipment operators to identify design and operational opportunities to extend the service life of coke drums for their specific service environments. A modern trend of specifying higher chromium and molybdenum alloy content for drum shell material in order to improve low cycle fatigue strength is seen to be problematic; rather, the use of lower alloy materials that are generally described as fatigue tough materials are better suited for the high strain-low cycle fatigue service environment of coke drums. Materials such as SA 204 C (C – ½ Mo) and SA 302 B (C – Mn – ½ Mo) or SA 302 C (C – Mn – ½ Mo – ½ Ni) are shown to be better candidates for construction in lieu of low chromium alloy steel materials such as SA 387 grades P11 (1¼ Cr – ½ Mo), P12 (1 Cr – ½ Mo), P22 (2¼ Cr – 1 Mo) and P21 (3 Cr – 1 Mo).

Fretting Wear Mechanisms and Their Effects on Fretting Fatigue

1988 ◽  
Vol 110 (3) ◽  
pp. 517-524 ◽  
Author(s):  
Y. Berthier ◽  
Ch. Colombie´ ◽  
L. Vincent ◽  
M. Godet
Keyword(s):  
Fretting Fatigue ◽  
Relative Displacement ◽  
Contact Condition ◽  
Fretting Wear ◽  
Initial Contact ◽  
Great Care ◽  
Third Body ◽  
Body Formation ◽  
The Third ◽  
Contact Surfaces

Fretting wear and fretting fatigue are governed by the rate of formation of materials (third-bodies) between the initial contact surfaces. Furthermore, the third-bodies must be maintained within the contact. The issue of the race between third-body formation and subsurface damage conditions the effect of fretting on fatigue. That race lasts for only a few hundred or at best a few thousand cycles. Effective third-bodies (or good anti-fretting lubricants) must adhere strongly to the rubbing surfaces, and be able to accommodate at least part of the relative displacement. Great care in the design of test equipment has to be exercised before definitive results on the effect of amplitude and frequency on either fretting fatigue or fretting wear can be obtained for a given contact condition, given materials and given environments.

A SIZE EFFECT STUDY ON THE SPLITTING CRACK INITIATION AND PROPAGATION IN OFF-AXIS LAYERS OF COMPOSITE LAMINATES

2021 ◽  
Author(s):  
YAO QIAO ◽  
QIWEI ZHANG ◽  
TROY NAKAGAWA ◽  
MARCO SALVIATO
Keyword(s):  
Crack Initiation ◽  
Size Effect ◽  
Fiber Reinforced Polymers ◽  
Structural Behavior ◽  
Crack Initiation And Propagation ◽  
Damage Mechanisms ◽  
Micro Scale ◽  
Morphological Studies ◽  
Initiation And Propagation ◽  
Macro Scale

This work proposes an investigation on size effects in micro-scale splitting crack initiation and propagation and their consequences on the macro-scale structural behavior carbon-fiber reinforced polymers under transverse tension. Towards this goal, size effect tests were experimentally conducted on both notch-free [90]n composites and specimens with different notch types under three-point bending. The mechanical tests were followed by morphological studies to identify the micro-scale damage mechanisms and their evolution. The results clearly show that splitting crack initiation in the transverse direction of composites not only happens at the fiber/matrix interface but also in the matrix. Moreover, the subsequent development of these damage mechanisms can depend on the structure size. This interesting phenomenon inherently leads to size-dependent structural behavior which can be described through Baznt’s Size Effect Laws. This study on the splitting crack initiation and propagation can provide unprecedented information for the calibration and validation of micromechanical models for the damage behavior of fiber composites at the microscale.

Numerical and digital image correlation analysis of tensile behavior of thin-ply hybrid laminates with discontinuous carbon sandwiched by continuous glass and carbon

2021 ◽  
pp. 002199832110565
Author(s):  
Amos Ichenihi ◽  
Wei Li ◽  
Li Zhe
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Element Model ◽  
Image Correlation ◽  
Continuous Glass ◽  
Damage Initiation ◽  
3D Digital Image Correlation ◽  
Initiation And Propagation ◽  
Hybrid Laminates ◽  
Strain Increase

Thin-ply hybrid laminates of glass and carbon fibers have been widely adopted in engineering pseudo-ductility. In this study, a Finite Element model is proposed using Abaqus to predict pseudo-ductility in thin-ply laminates consisting of three materials. These materials comprise continuous carbon (CC) and continuous glass sandwiching partial discontinuous carbon (DC). The model adopts the Hashin criterion for damage initiation in the fibers and the mixed-mode Benzeggagh-Kenane criterion on cohesive surfaces for delamination initiation and propagation. Numerically predicted stress–strain results are verified with experimental results under tensile loading. Results show pseudo-ductility increases with the increase in DC layers, and pseudo-yield strength and strain increase with the increase in CC layers. 3D-Digital Image Correlation results indicate delamination growth on pseudo-ductile laminates, and the calculated Poisson’s ratios show pseudo-ductility occurs below 0.27. Moreover, Poisson’s ratio decreases with an increase in pseudo-ductility.

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