Modeling and Validation of the Nonlinear Dynamic Behavior of Bolted Flange Joints

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
C. W. Schwingshackl ◽  
D. Di Maio ◽  
I. Sever ◽  
J. S. Green
Keyword(s):  
Nonlinear Analysis ◽  
Aircraft Engine ◽  
Nonlinear Damping ◽  
Element Analysis ◽  
Structural Support ◽  
Dynamic Finite Element Analysis ◽  
Damping Behavior ◽  
Bolted Flange ◽  
Engine Components

Linear dynamic finite element analysis can be considered very reliable today for the design of aircraft engine components. Unfortunately, when these individual components are built into assemblies, the level of confidence in the results is reduced since the joints in the real structure introduce nonlinearity that cannot be reproduced with a linear model. Certain types of nonlinear joints in an aircraft engine, such as underplatform dampers and blade roots, have been investigated in great detail in the past, and their design and impact on the dynamic response of the engine is now well understood. With this increased confidence in the nonlinear analysis, the focus of research now moves towards other joint types of the engine that must be included in an analysis to allow an accurate prediction of the engine behavior. One such joint is the bolted flange, which is present in many forms on an aircraft engine. Its main use is the connection of different casing components to provide the structural support and gas tightness to the engine. This flange type is known to have a strong influence on the dynamics of the engine carcase. A detailed understanding of the nonlinear mechanisms at the contact is required to generate reliable models and this has been achieved through a combination of an existing nonlinear analysis capability and an experimental technique to accurately measure the nonlinear damping behavior of the flange. Initial results showed that the model could reproduce the correct characteristics of flange behavior, but the quantitative comparison was poor. From further experimental and analytical investigations it was identified that the quality of the flange model is critically dependent on two aspects: the steady stress/load distribution across the joint and the number and distribution of nonlinear elements. An improved modeling approach was developed that led to a good correlation with the experimental results and a good understanding of the underlying nonlinear mechanisms at the flange interface.

Modelling and Validation of the Nonlinear Dynamic Behaviour of Bolted Flange Joints

2013 ◽  
Author(s):  
C. W. Schwingshackl ◽  
D. Di Maio ◽  
J. S. Green
Keyword(s):  
Aircraft Engine ◽  
Nonlinear Damping ◽  
Element Analysis ◽  
Structural Support ◽  
Dynamic Finite Element Analysis ◽  
Non Linear ◽  
Linear Elements ◽  
Bolted Flange ◽  
Engine Components

Linear dynamic finite element analysis can be considered very reliable today for the design of aircraft engine components. Unfortunately, when theses individual components are built into assemblies, the level of confidence in the results is reduced, since the joints in the real structure introduce nonlinearity that cannot be reproduced with a linear model. Certain types of nonlinear joints in an aircraft engine, such as underplatform dampers and blade roots, have been investigated in great detail in the past, and their design and impact on the dynamic response of the engine is now well understood. With this increased confidence in the nonlinear analysis, the focus of research now moves towards other joint types of the engine which must be included in an analysis to allow an accurate prediction of the engine behaviour. One such joint is the bolted flange, which is present in many forms on an aircraft engine. Its main use is the connection of different casing components to provide the structural support and gas tightness to the engine. This flange type is known to have a strong influence on the dynamics of the engine carcase. A detailed understanding of the nonlinear mechanisms at the contact is required to generate reliable models and this has been achieved through a combination of an existing non-linear analysis capability and an experimental technique to accurately measure the nonlinear damping behaviour of the flange. Initial results showed that the model could reproduce the correct characteristics of flange behaviour, but the quantitative comparison was poor. From further experimental and analytical investigations it was identified that the quality of the flange model is critically dependent on two aspects: the steady stress/load distribution across the joint and the number and distribution of non-linear elements. An improved modelling approach was developed which led to a good correlation with the experimental results and a good understanding of the underlying nonlinear mechanisms at the flange interface.

Modeling of Flange Joints for the Nonlinear Dynamic Analysis of Gas Turbine Engine Casings

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
C. W. Schwingshackl ◽  
E. P. Petrov
Keyword(s):  
Nonlinear Analysis ◽  
Gas Turbine ◽  
Normal Load ◽  
Nonlinear Dynamic Analysis ◽  
Aircraft Engine ◽  
Partial Slip ◽  
Analysis Tool ◽  
Flange Joint ◽  
Contact Interface ◽  
Element Analysis

The finite element analysis of individual components of aircraft engine casings provides high accuracy and a good agreement with the measured response data. However, when these components are assembled, the accuracy of such predictions can significantly deteriorate since models describing stiffness and friction properties of joints are linearized. A full nonlinear analysis of the casing flanges is required to fully include the influence of the bolted joints, model the flexibility in the contact interface, and consider the nonlinear behavior of the contact due to partial slip and separation. In this paper different nonlinear models of casings are investigated with an available nonlinear analysis tool: A parametric study of the contact interface meshes is conducted to identify a satisfying analysis approach. The dynamic flange behavior is analyzed in detail, including effects of the bolt and normal load distribution. A comparison of the introduced nonlinear modeling with more traditional rigid or linear-elastic flange joint models is carried out to evaluate the effect of the nonlinear approach. The study demonstrates the nonlinear nature of a casing flange joint and highlights the need to include them in the analysis. The detailed modeling of the contact interaction of joints gives an insight in the nonlinear contact behavior of flanges of aircraft engine casings, and the predictive capabilities for the nonlinear analysis of gas turbine engines.

scholarly journals Development of Artificial Neural Network Based Design Tool for Aircraft Engine Bolted Flange Connection Subject to Combined Axial and Moment Load

2017 ◽  
Author(s):  
T. Volkan Sanli ◽  
Ercan Gürses ◽  
Demirkan Çöker ◽  
Altan Kayran
Keyword(s):  
Neural Network ◽  
Finite Element Analysis ◽  
Artificial Neural Network ◽  
Finite Element ◽  
Aircraft Engine ◽  
Element Analysis ◽  
Flange Connection ◽  
Non Linear ◽  
Artificial Neural ◽  
Bolted Flange

Bolted flange connections are one of the most commonly used joint types in aircraft structures. Typically, bolted flange connections are used in aircraft engines. The main duty of a bolted flange connection in an aircraft engine is to serve as the load transfer interface from one part of the engine to the other part of the engine. In aircraft structures, weight is a very critical parameter which has to be minimized while having the required margin of safety for the structural integrity. Therefore, optimum design of the bolted flange connection is crucial to minimize the weight. In the preliminary design stage of the bolted flange connection, many repetitive analyses have to be made in order to decide on the optimum design parameters of the bolted flange connection. Two main methods used for analyzing bolted flange connections are the hand calculations based on simplified approaches and finite element analysis (FEA). While hand calculations lack achieving optimum weight as they tend to give over safe results, finite element analysis is computationally expensive because of the non-linear feature of the problem due to contact definitions between the mating parts. In this study, a fast but very accurate design tool based on artificial neural network (ANN) is developed for the cylindrical bolted flange connection of a typical aircraft engine under combined axial and bending moment load. ANN uses the FEA database generated by taking permutations of the parametric design variables of the bolted flange connection. The selected parameters are the number of bolts, the bolt size, the flange thickness, the web thickness, the preload level of the bolt and the external combined loads of bending moment and axial force. The bolt reaction force and the average flange stress are taken as the output variables and the results of 12000 different finite element analyses are gathered to form a database for the training of the ANN. Results of the trained ANN are then compared with the finite element analysis results and it is shown that an excellent agreement exists between the ANN and the non-linear finite element analysis results within the training limits of the artificial neural network. We believe that the ANN established can be a very robust and accurate approximate model replacing the non-linear finite element solver in the optimization of the bolted flange connection of the aircraft engine to achieve weight reduction.

Towards Predicting Relative Belt Edge Endurance With the Finite Element Method

1990 ◽  
Vol 18 (4) ◽  
pp. 216-235 ◽  
Author(s):  
J. De Eskinazi ◽  
K. Ishihara ◽  
H. Volk ◽  
T. C. Warholic
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Shear Deformations ◽  
Element Analysis ◽  
Vertical Loading ◽  
Predicted Values ◽  
Element Method

Abstract The paper describes the intention of the authors to determine whether it is possible to predict relative belt edge endurance for radial passenger car tires using the finite element method. Three groups of tires with different belt edge configurations were tested on a fleet test in an attempt to validate predictions from the finite element results. A two-dimensional, axisymmetric finite element analysis was first used to determine if the results from such an analysis, with emphasis on the shear deformations between the belts, could be used to predict a relative ranking for belt edge endurance. It is shown that such an analysis can lead to erroneous conclusions. A three-dimensional analysis in which tires are modeled under free rotation and static vertical loading was performed next. This approach resulted in an improvement in the quality of the correlations. The differences in the predicted values of various stress analysis parameters for the three belt edge configurations are studied and their implication on predicting belt edge endurance is discussed.

Numerical Analysis of Masonry under Compression via Micro-Model

2011 ◽  
Vol 243-249 ◽  
pp. 1360-1365 ◽  
Author(s):  
Wei Rong Lü ◽  
Meng Wang ◽  
Xi Jun Liu
Keyword(s):  
Joint Strength ◽  
Ultimate Load ◽  
Poor Quality ◽  
Micro Model ◽  
Element Analysis ◽  
Mortar Joint ◽  
The Poor ◽  
The Finite Element Analysis ◽  
Brick And Mortar

The micro-model, which the brick and the mortar model are separated, is used to analyze masonry. Meanwhile, the mortar is divided into three layers along the thickness direction to obtain the internal mechanical behavior of mortar, and the vertical mortar joint strength is taken as 50% strength of the horizontal mortar joint for considering the poor quality of vertical mortar joint. The compressive ultimate load and failure mode of masonry taken from the finite element analysis result, especially the vertical cracks throughout all bricks and mortar and change of brick and mortar strain, are in agreement with the experimental results. It shows that the micro-model and method adopted in paper are able to effectively apply in nonlinear structural analysis for masonry.

Benefits of Using Diamond Dies for Cold Alternate Drawing of Magnesium Alloys

2016 ◽  
Vol 716 ◽  
pp. 13-21 ◽  
Author(s):  
Vladimir Stefanov Hristov ◽  
Kazunari Yoshida
Keyword(s):  
Magnesium Alloy ◽  
Weight Ratio ◽  
High Strength ◽  
Wire Drawing ◽  
High Ductility ◽  
Element Analysis ◽  
The Wire ◽  
Shearing Strain ◽  
Drawing Method

In recent years, due to its low density and high strength/weight ratio, magnesium alloy wires has been considered for application in many fields, such as welding, electronics, medical field (for production of stents). But for those purposes, we need to acquire wires with high strength and ductility. For that we purpose we proposed alternate drawing method, which is supposed to highly decrease the shearing strain near the surface of the wire after drawing, by changing the direction of the wire drawing with each pass and thus acquiring high ductility wires.We have done research on the cold alternate drawing of magnesium alloy wires, by conducting wire drawing of several magnesium wires and testing their strength, hardness, structure, surface and also finite element analysis, we have proven the increase of ductility at the expense of some strength.In this research we are looking to further improve the quality of the drawn wires by examining the benefits of using diamond dies over tungsten carbine dies. Using the alternate drawing method reduces the strength of the drawn wires and thus lowering their drawing limit. By using diamond dies we are aiming to decrease the drawing stress and further increase the drawing limit of the alternate drawn wires and also improve the quality of the finishing surface of the wires. With this in mind we are aiming to produce a good quality wire with low diameter, high ductility, high strength and fine wire surface.

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