Mechanics Modeling of Blade/Disk Contacts

2005 ◽  
Author(s):  
Matthew C. Gean ◽  
Thomas N. Farris
Keyword(s):  
Finite Element ◽  
Singular Integral ◽  
Singular Integral Equations ◽  
Contact Stresses ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Contact Loads ◽  
Finite Element Calculations ◽  
Normal And Tangential Loads ◽  
Empirical Constants

A predictive procedure capable of calculating dovetail surface contact loads in gas turbine engines is developed. The procedure determines contact normal and tangential loads, for a complete mission involving radial blade and thermal loads. Once Finite Element calculations to determine empirical constants for a specific blade/disk geometry are completed, the predictive procedure handles complicated load histories in near real-time for both single and double tang dovetails. The resulting load histories can be combined with Singular Integral Equations to calculate edge-of-contact stresses. The resulting contact stresses have been used to successfully predict fretting fatigue lives under controlled laboratory conditions.

STATIC TESTS OF FULL-SIZE ACOUSTIC PANELS OF AIRCRAFT GAS-TURBINE ENGINES

2020 ◽  
pp. 18-23
Author(s):  
N. V. Osadchy ◽  
V. T. Shepel
Keyword(s):  
Finite Element ◽  
Gas Turbine ◽  
Flaw Detection ◽  
Static Strength ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Safe Operation ◽  
Static Tests ◽  
Finite Element Calculations ◽  
Comparison Of The Results

The article suggests the installation and methods of static tests for the limit working and fracture loads of acoustic panels of aircraft gas-turbine engines (GTE). It is not possible to perform the full scope of static tests on the engine as it is technically impossible to obtain the airflow pressures required by airworthiness standards. The required pressure in the proposed installation is created by the punch, which is the same shape as the panel to be tested. Flexible rubber sheets are used to equalize contact pressure on the panel surface. The similarity in the distribution of pressures on the surface of the acoustic panel created by the air flow as part of the GTE and the pressures created by the punch as part of the installation is confirmed by comparing the stresses and deformations obtained as a result of finite-element calculations. The article presents the results of certification static tests and flaw detection of a three-layer acoustic panel. Comparison of the results of finite-element calculations of stresses and displacements of the acoustic panel as a part of GTE and as a part of the installation has shown that in the latter case the estimations of static strength are conservative, which positively affects their safe operation.

On the receding contact between a graded and a homogeneous layer due to a flat-ended indenter

2021 ◽  
pp. 108128652110431
Author(s):  
Rui Cao ◽  
Changwen Mi
Keyword(s):  
Finite Element ◽  
Contact Problem ◽  
Integral Equations ◽  
Singular Integral ◽  
Functional Dependence ◽  
Singular Integral Equations ◽  
Homogeneous Layer ◽  
Cauchy Type ◽  
Receding Contact ◽  
Contact Pressures

This paper solves the frictionless receding contact problem between a graded and a homogeneous elastic layer due to a flat-ended rigid indenter. Although its Poisson’s ratio is kept as a constant, the shear modulus in the graded layer is assumed to exponentially vary along the thickness direction. The primary goal of this study is to investigate the functional dependence of both contact pressures and the extent of receding contact on the mechanical and geometric properties. For verification and validation purposes, both theoretical analysis and finite element modelings are conducted. In the analytical formulation, governing equations and boundary conditions of the double contact problem are converted into dual singular integral equations of Cauchy type with the help of Fourier integral transforms. In view of the drastically different singularity behavior of the stationary and receding contact pressures, Gauss–Chebyshev quadratures and collocations of both the first and the second kinds have to be jointly used to transform the dual singular integral equations into an algebraic system. As the resultant algebraic equations are nonlinear with respect to the extent of receding contact, an iterative algorithm based on the method of steepest descent is further developed. The semianalytical results are extensively verified and validated with those obtained from the graded finite element method, whose implementation details are also given for easy reference. Results from both approaches reveal that the property gradation, indenter width, and thickness ratio all play significant roles in the determination of both contact pressures and the receding contact extent. An appropriate combination of these parameters is able to tailor the double contact properties as desired.

Partial slip contact analysis for a monoclinic half plane

2020 ◽  
pp. 108128652096283
Author(s):  
İ Çömez ◽  
Y Alinia ◽  
MA Güler ◽  
S El-Borgi
Keyword(s):  
Integral Equations ◽  
Half Plane ◽  
Singular Integral ◽  
Integral Transform ◽  
Mixed Boundary ◽  
Normal Load ◽  
Fibrous Composite ◽  
Singular Integral Equations ◽  
Contact Stresses ◽  
Partial Slip

In this paper, the nonlinear partial slip contact problem between a monoclinic half plane and a rigid punch of an arbitrary profile subjected to a normal load is considered. Applying Fourier integral transform and the appropriate boundary conditions, the mixed-boundary value problem is reduced to a set of two coupled singular integral equations, with the unknowns being the contact stresses under the punch in addition to the stick zone size. The Gauss–Chebyshev discretization method is used to convert the singular integral equations into a set of nonlinear algebraic equations, which are solved with a suitable iterative algorithm to yield the lengths of the stick zone in addition to the contact pressures. Following a validation section, an extensive parametric study is performed to illustrate the effects of material anisotropy on the contact stresses and length of the stick zone for typical monoclinic fibrous composite materials.

Using a Dovetail Fixture to Study Fretting Fatigue and Fretting Palliatives

2003 ◽  
Vol 128 (2) ◽  
pp. 133-141 ◽  
Author(s):  
B. P. Conner ◽  
T. Nicholas
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Fatigue Damage ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Turbine Engines ◽  
Aluminum Bronze ◽  
Gas Turbine Engines ◽  
Contact Loads ◽  
Low Plasticity Burnishing

Fretting fatigue damage can reduce the service life of engineering components in contact. The attachment between blades and disks in the fan and compressor stages of gas turbine engines is often a dovetail geometry. As a result, normal and tangential cyclic contact loads are present. Results of fretting fatigue tests using a new dovetail fixture are detailed here. Dovetail specimens and three types of contact pads were all machined out of Ti−6A1−4V. Two types of palliatives are also examined: aluminum bronze coatings and low-plasticity burnishing. While the palliatives were effective in increasing the fatigue life, the three pad geometries produced essentially the same fatigue life.

Calculating blades of gas-turbine engines by the finite element method

1976 ◽  
Vol 8 (6) ◽  
pp. 683-688
Author(s):  
A. L. Kvitka ◽  
P. P. Voroshko ◽  
L. A. Zaslotskaya
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Gas Turbine ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
The Finite Element Method ◽  
Element Method

scholarly journals МОДЕЛИРОВАНИE ПРОЦЕССА ГОРЕНИЯ В ФАКЕЛЬНЫХ ВОСПЛАМЕНИТЕЛЯХ ГТД

2019 ◽  
pp. 39-49
Author(s):  
Юрий Иванович Торба ◽  
Сергей Игоревич Планковский ◽  
Олег Валерьевич Трифонов ◽  
Евгений Владимирович Цегельник ◽  
Дмитрий Викторович Павленко
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Computational Model ◽  
Gas Turbine ◽  
Test Bench ◽  
Combustion Process ◽  
Turbine Engines ◽  
Combustion Model ◽  
Gas Turbine Engines ◽  
Turbine Engine

The aim of the work was the development and testing of methods for modeling the combustion process in the torch igniters of gas turbine engines. To achieve it, the finite element method was used. The main results of the work are the substantiation of the need to optimize the torch igniters of gas turbine engines. The practice of operating torch igniters of various designs has shown that the stability of their work depends on the parameters of gas turbine engines and external factors (air and fuel temperature, size of fuel droplets, fuel and air consumption, as well as its pressure). At the same time, the scaling of the geometry of the igniter design does not ensure its satisfactory work in the composition of the GTE with modified parameters. In this regard, an urgent task is to develop a combustion model in a flare igniter to optimize its design. A computational model of a torch igniter for a gas turbine engine of a serial gas-turbine engine in a software package for numerical three-dimensional thermodynamic simulation of AN-SYS FLUENT has been developed. To reduce the calculation time and the size of the finite element model, recommendations on the adaptation of the geometric model of the igniter for numerical modeling are proposed. The mod-els of flow turbulence and combustion, as well as initial and boundary conditions, are selected and substantiated. Verification of the calculation results obtained by comparison of numerical simulation with the data of tests on a specialized test bench was performed. It is shown that the developed computational model makes it possible to simulate the working process in the torch igniters of the GTE combustion chambers of the investigated design with a high degree of confidence. The scientific novelty of the work consists in substantiating the choice of the combustion model, the turbulence model, as well as the initial and boundary conditions that provide adequate results to the full-scale experiment on a special test bench. The developed method of modeling the combustion process in gas turbine torch igniters can be effectively used to optimize the design of igniters based on GTE operation conditions, as well as combustion initialization devices to expand the range of stable operation of the combustion chamber. 

Mechanics Modeling of the Contact Loads on Dovetail Attachments

2010 ◽  
Vol 78 (2) ◽  
Author(s):  
Matthew C. Gean ◽  
Thomas N. Farris
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Life Prediction ◽  
Engine Performance ◽  
Local Stress ◽  
Fatigue Life Prediction ◽  
Performance Parameters ◽  
Finite Element Analyses ◽  
Contact Loads ◽  
Empirical Constants

A procedure for calculating contact loads on a dovetail surface for given engine performance parameters such as speed and temperature is described. The procedure requires a small number of predetermined calibrating finite element analyses to obtain empirical constants. Verification is provided by detailed finite element analyses. Contact loads can be calculated for an entire mission history in near real-time. The contact load histories could be used to calculate local stress necessary for fatigue life prediction.

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