scholarly journals Numerical Investigation of an Academic Mistuned Bladed Disk Dynamics Accounting for Blade/Casing Contacts

2019 ◽  
Author(s):  
Jeanne Joachim ◽  
Florence Nyssen ◽  
Alain Batailly
Keyword(s):  
Time Integration ◽  
Synthesis Method ◽  
Aircraft Engine ◽  
Element Model ◽  
Integration Scheme ◽  
Bladed Disk ◽  
Structural Context ◽  
Time Integration Scheme ◽  
Blade Tip ◽  
Linear And Nonlinear

Abstract This contribution focuses on the combined analysis of mistuning and unilateral blade-tip/casing contacts. A 2D phenomenological finite element model of an aircraft engine fan stage is considered. It is reduced by means of the Craig-Bampton component mode synthesis method and contact treatment relies on a Lagrange multiplier algorithm within an explicit time-integration scheme. Blade-tip/casing contacts are initiated through the deformed shape of a perfectly rigid casing. Mistuning is accounted for on the blades only. Monte Carlo simulations are carried out in both linear and nonlinear configurations, which allows to compare amplifications predicted in both context due to mistuning. Following a thorough convergence analysis of the proposed numerical strategy, the influence of mistuning level as well as the configuration of the external forcing are investigated. Presented results underline the detrimental consequences of mistuning in a nonlinear structural context, yielding even higher vibration amplifications than in a linear context. A cross-analysis between linear and nonlinear computations reveals that no correlation is found between linear and nonlinear amplifications which suggests that the effect of existing strategies to mitigate vibration amplifications within a linear context may not be suitable within a nonlinear context.

scholarly journals Numerical Investigation of a Mistuned Academic Bladed Disk Dynamics with Blade/Casing Contact

2020 ◽  
Author(s):  
Jeanne Joachim ◽  
Florence Nyssen ◽  
Alain Batailly
Keyword(s):  
Time Integration ◽  
Synthesis Method ◽  
Aircraft Engine ◽  
Element Model ◽  
Integration Scheme ◽  
Bladed Disk ◽  
Structural Context ◽  
Time Integration Scheme ◽  
Blade Tip ◽  
Linear And Nonlinear

Abstract This contribution focuses on the combined analysis of mistuning and unilateral blade-tip/casing contacts. A 2D phenomenological finite element model of an aircraft engine fan stage is considered. It is reduced by means of the Craig-Bampton component mode synthesis method and contact treatment relies on a Lagrange multiplier algorithm within an explicit time-integration scheme. Blade-tip/casing contacts are initiated through the deformed shape of a perfectly rigid casing. Mistuning is accounted for on the blades only. Monte Carlo simulations are carried out in both linear and nonlinear configurations, which allows to compare amplifications predicted in both context due to mistuning. Following a thorough convergence analysis of the proposed numerical strategy, the influence of mistuning level as well as the configuration of the external forcing are investigated. Presented results underline the detrimental consequences of mistuning in a nonlinear structural context, yielding even higher vibration amplifications than in a linear context. A cross-analysis between linear and nonlinear computations reveals that no correlation is found between linear and nonlinear amplifications which suggests that the effect of existing strategies to mitigate vibration amplifications within a linear context may not be suitable within a nonlinear context.

scholarly journals Aircraft Engine Structural Rotor-Stator Modal Interaction

2005 ◽  
Author(s):  
Mathias Legrand ◽  
Se´bastien Roques ◽  
Bernard Peseux ◽  
Christophe Pierre
Keyword(s):  
Equations Of Motion ◽  
Time Integration ◽  
Aircraft Engine ◽  
Travelling Wave ◽  
Integration Scheme ◽  
Frequency Domain Method ◽  
Vibration Modes ◽  
Jet Engines ◽  
Bladed Disk ◽  
Time Integration Scheme

In modern turbo machines such as aircraft jet engines, contact between the casing and bladed disk may occur through a variety of mechanisms: coincidence of vibration modes, thermal deformation of the casing, rotor imbalance, etc. These nonlinear interactions may result in severe damage to both structures and it is important to understand the physical mechanisms that cause them and the circumstances under which they occur. In this study, we focus on the phenomenon of interaction caused by modal coincidence. A simple two-dimensional model of the casing and bladed disk structures is introduced in order to predict the occurrence of the interaction phenomenon versus the rotation speed of the rotor. Each structure is represented in terms of its two k-nodal diameter vibration modes, which are characteristic of axi-symmetric structures and allow for travelling wave motions that may interact through direct contact. The equations of motion are solved using an explicit time integration scheme in conjunction with the Lagrange multiplier method where friction is considered. Results of the numerical tool and theory show good agreement in the prediction of rotational speed to be avoided. To conclude, the mathematical statements of a multi-frequency domain-method are proposed. This method is to be used to circumvent numerical issues inherent to time-marching procedures.

Dynamic Behaviour of Delaminated Composite Plate Under Blast Loading

2017 ◽  
Author(s):  
Chetan Kumar Hirwani ◽  
Subrata Kumar Panda ◽  
Siba Sankar Mahapatra ◽  
Sanjib Kumar Mandal ◽  
Apurba Kumar De
Keyword(s):  
Finite Element ◽  
Composite Plate ◽  
Degrees Of Freedom ◽  
Dynamic Behaviour ◽  
Time Integration ◽  
Blast Loading ◽  
Element Model ◽  
Continuity Condition ◽  
Integration Scheme ◽  
Time Integration Scheme

In the present article, the dynamic behaviour of the delaminated composite plate subjected to blast loading has been investigated. For the investigation, a general finite element model using higher-order mid-plane kinematics has been developed. The model has been discretised using nine noded isoparametric Lagrangian elements having nine degrees of freedom at each node. The continuity in the laminated and delaminated section has been established using the intermittent continuity condition. The final governing equation has been solved by applying Newmark’s time integration scheme in conjunction with finite element steps. Further, the said responses have been evaluated by developing an in-house MATLAB code based on the proposed model. In order to illustrate the consistency and accuracy of the present model, convergence and comparison study has been conducted i.e. the responses are evaluated for different mesh sizes and compared them with those of responses of earlier published literature. Finally, various examples have been solved to illustrate the influence of the size and position of debonding, side to thickness ratio, aspect ratio and end condition on the dynamic response of composite structure and discussed in detail.

Modeling of 3D Magnetostrictive Systems with Application to Galfenol and Terfenol-D Actuators

2012 ◽  
Vol 77 ◽  
pp. 11-28
Author(s):  
Marcelo J. Dapino ◽  
Suryarghya Chakrabarti
Keyword(s):  
Finite Element ◽  
Time Integration ◽  
Three Dimensional ◽  
Nonlinear Dynamic System ◽  
Element Model ◽  
Implicit Time ◽  
Integration Scheme ◽  
Modeling Framework ◽  
Time Integration Scheme ◽  
Parametric Analyses

This work presents a unified approach to model three dimensional magnetostrictive transducers. Generalized procedures are developed for incorporating nonlinear coupled constitutive behavior of magnetostrictive materials into an electro-magneto-mechanical finite element modeling framework. The finite element model is based on weak forms of Maxwell's equations for electromagnetics and Navier's equations for mechanical systems. An implicit time integration scheme is implemented to obtain nonlinear dynamic system responses. The model is implemented into a finite element (FE) solver and applied to two case studies, a Galfenol unimorph actuator and a magnetohydraulic Terfenol-D actuator for active engine mounts. Model results are compared with experiments, and parametric analyses are conducted which provide guidelines for optimization of actuator design.

scholarly journals Structural modal interaction of a four degree-of-freedom bladed disk and casing model

2010 ◽  
Vol 5 (4) ◽  
Author(s):  
Mathias Legrand ◽  
Christophe Pierre ◽  
Bernard Peseux
Keyword(s):  
Traveling Waves ◽  
Rotational Velocity ◽  
Equations Of Motion ◽  
Specific Interaction ◽  
Time Integration ◽  
Harmonic Balance Method ◽  
Integration Scheme ◽  
Nodal Diameter ◽  
Bladed Disk ◽  
Time Integration Scheme

Consideration is given to a very specific interaction phenomenon that may occur in turbomachines due to radial rub between a bladed disk and surrounding casing. These two structures, featuring rotational periodicity and axisymmetry, respectively, share the same type of eigenshapes, also termed nodal diameter traveling waves. Higher efficiency requirements leading to reduced clearance between blade-tips and casing together with the rotation of the bladed disk increase the possibility of interaction between these traveling waves through direct contact. By definition, large amplitudes as well as structural failure may be expected. A very simple two-dimensional model of outer casing and bladed disk is introduced in order to predict the occurrence of such phenomenon in terms of rotational velocity. In order to consider traveling wave motions, each structure is represented by its two nd-nodal diameter standing modes. Equations of motion are solved first using an explicit time integration scheme in conjunction with the Lagrange multiplier method, which accounts for the contact constraints, and then by the harmonic balance method (HBM). While both methods yield identical results that exhibit two distinct zones of completely different behaviors of the system, HBM is much less computationally expensive.

An Improved Sub-Step Composite Time Integration Formulation With Enhanced Performance on Linear and Nonlinear Dynamics

2021 ◽  
pp. 2150017
Author(s):  
W. B. Wen ◽  
S. Y. Deng ◽  
T. H. Liu ◽  
S. Y. Duan ◽  
W. Q. Hou ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Time Integration ◽  
Nonlinear Problems ◽  
Numerical Dissipation ◽  
Integration Scheme ◽  
Promising Candidate ◽  
Simple Formulation ◽  
Time Integration Scheme ◽  
Linear And Nonlinear ◽  
Period Elongation

An improved time integration scheme is proposed for linear and nonlinear dynamics. The proposed scheme has two free parameters which control numerical dissipation and accuracy effectively. Basic properties including spectral stability, algorithmic accuracy, algorithmic damping, period elongation and overshooting behavior are investigated. The influences of algorithmic parameters on these properties are quantified. The effectiveness of the proposed scheme for linear and nonlinear dynamics is evaluated through some numerical examples. Analytical and numerical results demonstrate that the proposed scheme has the following significant characteristics: (1) desirable accuracy can be obtained for various linear and nonlinear problems, when compared with other effective schemes; (2) for nonlinear problems, new scheme also shows good performance; (3) the proposed scheme has simple formulation and good compatibility for various dynamic problems, and thus, is a promising candidate for practical analysis.

A Finite Element Analysis for Unbonded Flexible Risers Under Axial Tension

2008 ◽  
Author(s):  
Ali Bahtui ◽  
Hamid Bahai ◽  
Giulio Alfano
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Time Integration ◽  
Element Model ◽  
Integration Scheme ◽  
Element Analysis ◽  
Time Integration Scheme ◽  
Flexible Risers ◽  
Benchmark Solutions ◽  
The Finite Element Model

Recent developments on the numerical analysis of detailed finite element models of unbonded flexible risers using ABAQUS are presented. Several analytical methods are studied and combined together, and their results are compared with those obtained in the finite element model for two different tests, the second one involving cyclic loading. In the finite element model all layers are modeled separately and contact interfaces are placed between each layer. A fully explicit time-integration scheme was used on a 16-processor cluster. The very good agreement found from numerical and analytical comparisons validates the use of our numerical model to provide benchmark solutions against which further detailed investigation will be made.

Numerical and Analytical Modeling of Unbonded Flexible Risers

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
A. Bahtui ◽  
H. Bahai ◽  
G. Alfano
Keyword(s):  
Finite Element ◽  
Time Integration ◽  
Computational Cost ◽  
Element Model ◽  
Integration Scheme ◽  
Element Analysis ◽  
Axial Tension ◽  
External Pressures ◽  
Time Integration Scheme ◽  
Flexible Risers

This paper presents an analytical formulation and a finite element analysis of the behavior of multilayer unbonded flexible risers. The finite element model accurately incorporates all the fine details of the riser that were previously considered to be important but too difficult to simulate due to the significant associated computational cost. All layers of the riser are separately modeled, and contact interaction between layers has been accounted for. The model includes geometric nonlinearity as well as frictional effects. The analysis considers the main modes of flexible riser loading, which include internal and external pressures, axial tension, torsion, and bending. Computations were performed by employing a fully explicit time integration scheme on a parallel 16-processor cluster of computers. Consistency of simulation results was demonstrated by comparison with those of the analytical model of an identical structure. The close agreement gives confidence in both approaches.

scholarly journals Structural Reliability Sensitivities under Nonstationary Random Vibrations

2013 ◽  
Vol 2013 ◽  
pp. 1-21 ◽  
Author(s):  
Rita Greco ◽  
Francesco Trentadue
Keyword(s):  
Structural Reliability ◽  
Structural Parameters ◽  
Time Integration ◽  
Structural Response ◽  
Integration Scheme ◽  
Structural Systems ◽  
Frame Building ◽  
Time Integration Scheme ◽  
Noise Input ◽  
The Time Domain

Response sensitivity evaluation is an important element in reliability evaluation and design optimization of structural systems. It has been widely studied under static and dynamic forcing conditions with deterministic input data. In this paper, structural response and reliability sensitivities are determined by means of the time domain covariance analysis in both classically and nonclassically damped linear structural systems. A time integration scheme is proposed for covariance sensitivity. A modulated, filtered, white noise input process is adopted to model the stochastic nonstationary loads. The method allows for the evaluation of sensitivity statistics of different quantities of dynamic response with respect to structural parameters. Finally, numerical examples are presented regarding a multistorey shear frame building.

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