An Understanding of Stress and Pretension Behavior of Aero Engine Rotor Bolted Joint

2021 ◽  
Author(s):  
Venkateshwarlu Mogullapally ◽  
Shine Jyoth ◽  
Sanju Kumar ◽  
Rashmi Rao ◽  
Rajeevalochanam B. A.
Keyword(s):  
Finite Element ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Structural Integrity ◽  
Dissimilar Materials ◽  
Bolted Joints ◽  
Working Environment ◽  
Bolted Joint ◽  
3D Finite Element ◽  
Nonlinear Stress

Abstract Bolted joints in gas turbines are used commonly to connect the parts of dissimilar materials to facilitate assembly, dis-assembly, and also to achieve modularity for advanced aero engines. In gas turbine engine, there are many rotating and stationary parts that are subjected to an extreme working environment. Bolted joints should have sufficient strength to support the mating parts such as safety critical fan/turbine discs, drums, and shaft assembly. Bolted joints are designed to avoid flange separation and slippage. This paper attempts to understand the challenges faced in designing a typical fan disc rotor plain flange type bolted assembly and structural integrity aspects under various thermo-mechanical operating loads. The understanding of stiffness of the bolt and joint members is necessary to evaluate the performance of the joint assembly. Based on literature, different approaches are used for estimating member stiffness to compare with finite element results. The effect of external loads such as thermo-mechanical loads on pretension behavior of bolted joint is studied with the help of standard commercial software platform ANSYS. Bolted joint preload loss has been assessed via the standard analytical method and validated with 3D finite element approach. This paper enables designer a quick understanding of rotor bolted joint behavior for finalization of gas turbine rotor layout, before going into complex and time consuming 3D finite element modelling and nonlinear stress analysis.

Finite Element Analysis to Verify the Structural Integrity of an Aeronautical Gas Turbine Disc Made from Inconel 713LC Superalloy

2019 ◽  
Vol 32 ◽  
pp. 15-26
Author(s):  
Alexandre Domingos Sarti Leme ◽  
Geraldo Creci ◽  
Edilson Rosa Barbosa de Jesus ◽  
Túlio César Rodrigues ◽  
João Carlos Menezes
Keyword(s):  
Finite Element ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Thermal Stresses ◽  
Failure Modes ◽  
Structural Integrity ◽  
Normal Operation ◽  
Element Analysis ◽  
Turbine Disc ◽  
Analysis Of Results

Gas turbines are very important because they can be used in several areas, such as aeronautics and electric power generation systems. The operation of a gas turbine can be done by less pollutant fuels when compared to traditional kerosene, for example, resulting in less degradation to environment. Gas turbines may fail from a variety of sources, with the possibility of serious damage results. In this work, the structural integrity of the hot disc of an aeronautical gas turbine is addressed. Several numerical analyses have been performed by the finite element method: Temperature Distributions, Thermal Stresses and Dilatations, Structural Stresses and Deformations, Modal Behaviors and Fatigue Analysis. Creep of blades has also been considered. These are the most important failure modes that can happen to the studied hot disc under operating service. All these analysis have been performed considering the boundary conditions at the design point with maximum rotational speed. The mesh of the problem has been strictly evaluated by adaptive refinement of nodes and elements combined with a convergence analysis of results. Then, the material and basic properties of the hot disc have been defined to assure a normal operation free from failures. Therefore, the mechanical drawings of the studied hot turbine disc have been released for manufacturing and the construction of the first prototype of the aeronautical gas turbine is in testing phase showing that the results presented in this work are consistent.

Representation of bolted joints in a structure using finite element modelling and model updating

2020 ◽  
Vol 14 (3) ◽  
pp. 7141-7151 ◽  
Author(s):  
R. Omar ◽  
M. N. Abdul Rani ◽  
M. A. Yunus
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Model Updating ◽  
Complex Structure ◽  
Bolted Joints ◽  
Model Parameters ◽  
Fe Model ◽  
Bolted Joint ◽  
Fe Modelling ◽  
Joint Structure

Efficient and accurate finite element (FE) modelling of bolted joints is essential for increasing confidence in the investigation of structural vibrations. However, modelling of bolted joints for the investigation is often found to be very challenging. This paper proposes an appropriate FE representation of bolted joints for the prediction of the dynamic behaviour of a bolted joint structure. Two different FE models of the bolted joint structure with two different FE element connectors, which are CBEAM and CBUSH, representing the bolted joints are developed. Modal updating is used to correlate the two FE models with the experimental model. The dynamic behaviour of the two FE models is compared with experimental modal analysis to evaluate and determine the most appropriate FE model of the bolted joint structure. The comparison reveals that the CBUSH element connectors based FE model has a greater capability in representing the bolted joints with 86 percent accuracy and greater efficiency in updating the model parameters. The proposed modelling technique will be useful in the modelling of a complex structure with a large number of bolted joints.

Accurate Evaluation of Bolt and Clamped Members Stiffnesses Of Bolted Joints

2021 ◽  
Author(s):  
Rashique Iftekhar Rousseau ◽  
Abdel-Hakim Bouzid ◽  
Zijian Zhao
Keyword(s):  
Finite Element ◽  
Joint Stiffness ◽  
Element Model ◽  
Fe Analysis ◽  
Bolted Joints ◽  
Analytical Models ◽  
Fe Modeling ◽  
Bolted Joint ◽  
A New Technique ◽  
External Loads

Abstract The axial stiffnesses of the bolt and clamped members of bolted joints are of great importance when considering their integrity and capacity to withstand external loads and resist relaxation due to creep. There are many techniques to calculate the stiffnesses of the joint elements using finite element (FE) modeling, but most of them are based on the displacement of nodes that are selected arbitrarily; therefore, leading to inaccurate values of joint stiffness. This work suggests a new method to estimate the stiffnesses of the bolt and clamped members using FE analysis and compares the results with the FE methods developed earlier and also with the existing analytical models. A new methodology including an axisymmetric finite element model of the bolted joint is proposed in which the bolts of different sizes ranging from M6 to M36 are considered for the analysis to generalize the proposed approach. The equivalent bolt length that includes the contribution of the thickness of the bolt head and the bolt nominal diameter to the bolt stiffness is carefully investigated. An equivalent bolt length that accounts for the flexibility of the bolt head is proposed in the calculation of the bolt stiffness and a new technique to accurately determine the stiffness of clamped members are detailed.

scholarly journals Nonlinear Axial Stiffness Characteristics of Axisymmetric Bolted Joints

1990 ◽  
Vol 112 (3) ◽  
pp. 442-449 ◽  
Author(s):  
I. R. Grosse ◽  
L. D. Mitchell
Keyword(s):  
Finite Element ◽  
Linear Theory ◽  
Design Theory ◽  
Joint Stiffness ◽  
Bolted Joints ◽  
Axial Stiffness ◽  
Outer Diameter ◽  
Bolted Joint ◽  
Element Analysis ◽  
Stiffness Characteristics

A critical assessment of the current design theory for bolted joints which is based on a linear, one-dimensional stiffness analysis is presented. A detailed nonlinear finite element analysis of a bolted joint conforming to ANSI standards was performed. The finite element results revealed that the joint stiffness is highly dependent on the magnitude of the applied load. The joint stiffness changes continuously from extremely high for small applied loads to the bolt stiffness during large applied loads, contrary to the constant joint stiffness of the linear theory. The linear theory is shown to be inadequate in characterizing the joint stiffness. The significance of the results in terms of the failure of bolted joints is discussed. A number of sensitivity studies were carried out to assess the effect of various parameters on the axial joint stiffness. The results revealed that bending and rotation of the joint members, interfacial friction, and the bolt/nut threading significantly influence the axial stiffness characteristics of the bolted joint. The two-dimensional, axisymmetric finite element model includes bilinear gap elements to model the interfaces. Special orthotropic elements were used to model the bolt/nut thread interaction. A free-body-diagram approach was taken by applying loads to the outer diameter of the joint model which correspond to internal, uniformly distributed line-shear and line-moment loads in the joint. A number of convergence studies were performed to validate the solution.

Bearing Housing Design for Vibration Control, Using Tilting Pad Bearings Instead of Lemon-Bore Type on a Gas Turbine

2020 ◽  
Author(s):  
Chippa Anil ◽  
Aparna Satheesh ◽  
Babu Santhanagopalakrishnan ◽  
Marcin Bielecki
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Structural Integrity ◽  
Plane Surface ◽  
Rotor Dynamics ◽  
Turbine Rotor ◽  
Outer Diameter ◽  
Housing Design ◽  
Tilting Pad ◽  
And Performance

Abstract Heavy duty gas turbines are usually equipped with hydrodynamic bearings which are either lemon-bore or tilting pad type. Baker Hughes legacy gas turbines use these two types of bearings, and its selection is based on 1) considering pros & cons from Rotor dynamics, 2) bearing performance, 3) bearing housing stiffness, 4) vibration detection & control. Non-contact probes are used to monitor the vibrations of rotor. Majority of legacy gas turbines are not equipped with these probes. Due to this fact, over the years it resulted in non-detection of dynamics & vibration issue, which caused frequent bearing replacement. As the increase in industry demand to apply and measure vibrations using non-contact probes on bearings, an effort was made by Baker Hughes to implement these on existing fleet units. Also, in order to increase rotor dynamics stability of low-pressure rotor, to improve bearing life and performance, effort was made to replace lemon-bore bearings with tilting pad. This paper demonstrates efforts made to design the titling pad which would fit within envelop of already available bearing housing. Bearing/shaft clearance, bearing performance, modification of bearing retainer clearances are the mandatory tasks which would be dealt in this study. The swap of bearing type, and its effect on whole gas turbine rotor dynamic stability, checking the frequency crossovers with Campbell diagram would also be dealt in this paper. This paper also focuses on assessment on oil passage routing, temperature & proximity probe instrumentation routing design. Re-design is performed by analyzing various configuration, assessing different sensitivity studies & validation of modified bearing housing from structural integrity, ultimate load capability, & split plane oil leakage retention and its comparison with baseline are most important aspects of finalization of this change, which will be showcased in this paper. Instrumentation routing was a critical task when the considering bearing replacement from lemon-bore to tilting pad. As lemon-bore type bearings just have an elliptical inner surface, it’s quite easy to install the thermocouples into a simple hole. But as replacement has tilting pads, the challenge is to instrument the pads without effecting their movement and functionality. Such best practices are also dealt in this paper. Comparison of tilting-pad with lemon-bore, considering the fixed shaft diameter, the retainer outer diameter of tilting pad is higher than lemon-bore. This effect has a change in bearing seat on bearing housing, thereby reducing the effective stiffness of the housing, and the reduced split plane surface. To tackle this situation, several sensitivities were executed, by re-modifying the bolts and bolt holes on the existing housing, without modifying the housing envelop.

Early Fault Detection of Hot Components in Gas Turbines

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Liu Jinfu ◽  
Liu Jiao ◽  
Wan Jie ◽  
Wang Zhongqi ◽  
Yu Daren
Keyword(s):  
Fault Detection ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Working Environment ◽  
Detection Sensitivity ◽  
Normal Operation ◽  
Large Temperature ◽  
Ambient Conditions ◽  
Fisher Discriminant Analysis ◽  
Early Fault Detection

The working environment of hot components is the most adverse of all gas turbine components. Malfunction of hot components is often followed by catastrophic consequences. Early fault detection plays a significant role in detecting performance deterioration immediately and reducing unscheduled maintenance. In this paper, an early fault detection method is introduced to detect early fault symptoms of hot components in gas turbines. The exhaust gas temperature (EGT) is usually used to monitor the performance of the hot components. The EGT is measured by several thermocouples distributed equally at the outlet of the gas turbine. EGT profile is symmetrical when the unit is in normal operation. And the faults of hot components lead to large temperature differences between different thermocouple readings. However, interferences can potentially affect temperature differences, and sometimes, especially in the early stages of the fault, its influence can be even higher than that of the faults. To improve the detection sensitivity, the influence of interferences must be eliminated. The two main interferences investigated in this study are associated with the operating and ambient conditions, and the structure deviation of different combustion chambers caused by processing and installation errors. Based on the basic principles of gas turbines and Fisher discriminant analysis (FDA), a new detection indicator is presented that characterizes the intrinsic structure information of the hot components. Using this new indicator, the interferences involving the certainty and the uncertainty are suppressed and the sensitivity of early fault detection in gas turbine hot components is improved. The robustness and the sensitivity of the proposed method are verified by actual data from a Taurus 70 gas turbine produced by Solar Turbines.

Study of bolted joint axial stiffness using finite element analyses, experimental tests, and analytical calculations

2020 ◽  
Vol 234 (23) ◽  
pp. 4671-4681
Author(s):  
Raphael Calazans Cardoso ◽  
Brenno Lima Nascimento ◽  
Felipe de Freitas Thompson ◽  
Sandro Griza
Keyword(s):  
Finite Element ◽  
Analytical Method ◽  
High Reliability ◽  
Experimental Tests ◽  
Bolted Joints ◽  
Axial Stiffness ◽  
Bolted Joint ◽  
Finite Element Analyses ◽  
Load Distributions ◽  
Reliable Design

The bolted joints sizing procedures shall adequately match the conditions imposed on the joint in service, to ensure high reliability designs. Therefore, this study aims to analyze the load distributions on the bolt when applying external load on bolted joints. Finite element and extensometry analyses as well as analytical calculations were performed in order to compare the magnitude of the joint overall stiffness, with respect to several available theories. The results acquired through the analytical method prescribed in the VDI 2230 standard as well as the finite element and extensometry analyses obtained great accordance. These results indicate that VDI 2230 standard adequately represents the mechanical behavior of the joint and should be used as a guideline for the reliable design of bolted joints subjected to the loading conditions of the present paper.

Nonlinear Behavior of Preloaded Bolted Joints Under a Cyclic Separating Load

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Xianjie Yang ◽  
Sayed A. Nassar ◽  
Zhijun Wu ◽  
Aidong Meng
Keyword(s):  
Finite Element ◽  
Deformation Behavior ◽  
Nonlinear Behavior ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Element Analysis ◽  
Linear Elastic ◽  
Plastic Deformation Behavior ◽  
Service Load ◽  
Joint Material

The nonlinear plastic deformation behavior of a clamped bolted joint model under a separating service load is investigated using analytical, finite element, and experimental techniques. An elastic-plastic model is used for the bolt material while the joint material remains in the linear elastic range. Both the analytical and finite element analysis (FEA) models investigate the variation in the tension of a preloaded bolt due to a separating service load that acts with an offset from the bolt center. Experimental verification is provided for both the analytical and finite element results on the bolt tension variation, clamp load variation and the clamp load loss caused by the incremental plastic bolt elongation under cyclic separating force.

Numerical Study of an Impusively Loaded Vessel Containing Double Versus Single Closure Bolt Patterns

2017 ◽  
Author(s):  
Joseph E. D. Hess
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Numerical Study ◽  
Axial Loading ◽  
Element Model ◽  
Pressure Vessels ◽  
Bolted Joint ◽  
Single Row ◽  
Asme Code ◽  
Calculation Results

Impulsively loaded pressure vessels are often closed using a bolted joint configured in a double staggered row pattern. The bolted joint design must maintain the placement of the vessel opening covers to support the structural integrity of the shell and also provide the necessary preload of sealing surfaces for leak prevention. Good design practice suggests configuring tensile loaded bolted joints with a double rows pattern in order to minimize prying against the bolt head induced by localized moments. Double bolt row patterns allow moments induced by load offsets to be reacted through contact of the faying surfaces of the bolted members and if separation occurs by differential axial loading of the two bolt rows. This acts to reduce direct prying of the mated members against the bolt heads. Material cost and operational time savings could be realized if a single bolt row design with acceptable performance was implemented. In this paper a detailed finite element model is described and calculation results are presented for two vessel configurations subjected to an impulsive load; a double staggered 64 bolt pattern and a single row 32 bolt pattern. Finite element results are compared to each other and to the rules of ASME Code Case 2564 in Section VIII, Division 3. Special attention is given to the loading induced in the bolts and to the relative deflection of faying surfaces containing seals. It will be shown that reducing the bolt count per opening from 64 to 32 results in increased peak response of the bolts, seal opening gaps, and shell. Nonetheless a single row bolt pattern does appear feasible and within the bounds of the Code Case.

Oyster Creek Nuclear Generating Station Containment Drywell Buckling Analysis

2010 ◽  
Author(s):  
Soo Bee Kok ◽  
Shu S. Tang ◽  
Francis H. Ku ◽  
Marcos L. Herrera ◽  
John F. O’Rourke ◽  
...  
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Buckling Analysis ◽  
Eigenvalues And Eigenvectors ◽  
Analysis Software ◽  
Element Analysis ◽  
3D Finite Element ◽  
Buckling Stability ◽  
Stability Limits

This article presents the overall methodology and the results of the three-dimensional (3D) finite element buckling analysis of the primary containment drywell shell at the Oyster Creek Nuclear Generating Station (Oyster Creek). The buckling stresses, eigenvalues, and eigenvectors are computed using ANSYS finite element analysis software [1], and the structural integrity of the drywell in terms of the buckling (stability) limits are based on the ASME B&PV Code Case N-284-1 [2].

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