Forced Response of Shrouded Bladed Disc Assemblies: A Jointed Experimental Numerical Approach

2004 ◽  
Author(s):  
F. D’Ambrosio ◽  
E. Chatelet ◽  
J. Ravoux ◽  
G. Jacquet-Richardet
Keyword(s):  
Dynamic Behavior ◽  
Dry Friction ◽  
Flexible Structures ◽  
Numerical Approach ◽  
Forced Response ◽  
Friction Damper ◽  
Element Analysis ◽  
First Results ◽  
Numerical Finite Element ◽  
Set Up

The objective of the proposed study is to progress towards a better modeling of bladed assemblies dynamic. Coupling devices are introduced in bladed stages to increase frequencies of resonance above the range of possible excitations. Commonly they are not only used to stiffen flexible structures but also to increase damping by dry friction, reducing the amplitude of vibration. Consequently, the resulting dynamic behavior is complex and highly non linear. In order to improve numerical capabilities used for the design of part span shrouds and to gain a better understanding of the dynamic behavior of shrouded assemblies, a jointed experimental and numerical approach has been conducted. A first experimental test based on a cantilever beam is considered. The beam, excited by a controlled electrodynamic shaker, is associated to a dry friction damper at its free end. A numerical finite element analysis and a macroslip model of contact has been developed. The solution method in time domain allows accurate computations of response levels and gives the main harmonics of the steady state response. Comparison between numerical and experimental results is very good. A second experimental set up is constituted by an assembly of 13 beams, cyclically mounted around a common disk and linked by geometrically simplified shrouds. The set up allows controlling the resultant forces in the contact and is able to exhibit all states of contact from fully slipping to fully stuck. The first results obtained are associated to a single couple of blades brought into contact.

Modelling a Friction Damper: Analysis of the Experimental Data and Comparison With Numerical Results

2006 ◽  
Author(s):  
Christian M. Firrone ◽  
Daniele Botto ◽  
Muzio M. Gola
Keyword(s):  
Experimental Data ◽  
Dry Friction ◽  
Negative Impact ◽  
Real Life ◽  
Forced Response ◽  
Nonlinear Frequency ◽  
Friction Damper ◽  
Typical Application ◽  
Static Test ◽  
Underplatform Damper

High cycle fatigue is one of the main causes of failure of blades in turbomachinery. The negative impact of HCF on turbomachinery blades can be reduced by dry friction vibration damping. A typical application of dry friction damping in gas turbine is the so called “underplatform damper”. In this work a ‘real life’ asymmetric underplatform damper is experimentally tested with two real blades. A static test rig is used to obtain the nonlinear frequency response function of a mock-up made with two real blades with an underplatform damper between them. This paper addresses an underplatform damper model taking into account damper rotation. The proper mathematical formulations have been developed and forced response calculation of the system have been performed. Comparison with experimental data are carried out for different values of excitation forces and for pre-load similar to real centrifugal force values.

A Finite Element Analysis of Friction Damping in a Slip Joint

1999 ◽  
Author(s):  
Weijiang Chen ◽  
Xiaomin Deng
Keyword(s):  
Finite Element ◽  
Dynamic Behavior ◽  
Dry Friction ◽  
Numerical Test ◽  
Structural Models ◽  
Bolted Joints ◽  
Joint Interface ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Lumped Parameter

Abstract Micro-slip along frictional interfaces often provides the dominant damping mechanism in a built-up structure and plays an important role in the dynamic behavior of the structure. This paper presents the results of a finite element study of the effect of dry friction on the damping response of a slip joint. The emphasis of this paper is to understand the evolution of the slip and stick regions along the joint interface during loading and to quantify the amount of energy dissipation during cyclic loading and its dependence on structural and loading parameters. Finite element predictions have been compared to experimental measurements and early analytical predictions in the literature. This study seems to demonstrate the potential of the finite element method in providing adequate “numerical” test data for formulating lumped-parameter structural models that can simulate the nonlinear dynamic behavior of bolted joints.

Experimental Investigation on the Forced Response of a Dummy Counter Rotating Turbine Stage With Friction Damping

2012 ◽  
Author(s):  
Teresa Berruti ◽  
Vanni Maschio ◽  
Paolo Calza
Keyword(s):  
Experimental Investigation ◽  
Dynamic Behavior ◽  
Dry Friction ◽  
Vibration Damping ◽  
Forced Response ◽  
Test Results ◽  
Turbine Stage ◽  
Friction Damping ◽  
Experimental Activity ◽  
Open Rotor

The paper shows the results of the experimental activity about the dynamics of a stage of a counter rotating turbine of an open rotor architecture engine. The tests here presented explore the dynamic behavior of a simplified counter-rotating turbine stage. The test results show the dynamic behavior of a counter rotating turbine stage and highlight the importance of the presence of dry friction for vibration damping.

Experimental Investigation on the Forced Response of a Dummy Counter-Rotating Turbine Stage With Friction Damping

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
Teresa Berruti ◽  
Vanni Maschio
Keyword(s):  
Experimental Investigation ◽  
Dynamic Behavior ◽  
Dry Friction ◽  
Vibration Damping ◽  
Forced Response ◽  
Test Results ◽  
Turbine Stage ◽  
Friction Damping ◽  
Experimental Activity ◽  
Open Rotor

The paper shows the results of the experimental activity about the dynamics of a stage of a counter-rotating turbine of an open rotor architecture engine. The tests presented here explore the dynamic behavior of a simplified counter-rotating turbine stage. The test results show the dynamic behavior of a counter-rotating turbine stage and highlight the importance of the presence of dry friction for vibration damping.

Blades Forced Response Analysis With Friction Dampers

1998 ◽  
Vol 120 (2) ◽  
pp. 468-474 ◽  
Author(s):  
M. Berthillier ◽  
C. Dupont ◽  
R. Mondal ◽  
J. J. Barrau
Keyword(s):  
Time Domain ◽  
Dry Friction ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Forced Response ◽  
Response Analysis ◽  
Friction Damper ◽  
Friction Dampers ◽  
Fan Blade

A multiharmonic frequency domain analysis combined with a Craig-Bampton component mode synthesis is presented to compute the dry friction damped forced response of blades. The accuracy of the analysis is established, for a cantilever beam with a dry friction damper attached, by comparison with experimental results and time domain analysis. The method has then been applied to a model fan blade damped by a blade to ground damper.

Design of a cutting head for a crosscutting machine

2016 ◽  
Vol 231 (1) ◽  
pp. 5-17 ◽  
Author(s):  
D Croccolo ◽  
M De Agostinis ◽  
S Fini
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Analysis ◽  
Dynamic Behavior ◽  
Analytical Model ◽  
Analytical Models ◽  
Rectangular Section ◽  
Element Analysis ◽  
Cutting Head ◽  
Numerical Finite Element

The present paper deals with the structural analysis and the re-design of a cutting head for an automatic crosscutting machine. The machine is already marketed, and can process rectangular section wooden slats. The principal goal of this work is to develop a new mechanism capable of enhancing the productivity of the machine by around 80%. The work has been carried out by means of both numerical finite element analysis tools and analytical models. In fact, a secondary aim of the research is to define an analytical model which can capture the dynamic behavior of the device: this tool will be helpful to the design engineer in order to save costs associated with the development of future head designs.

Trace element analysis on Si wafer surfaces by TXRF at the ID32 ESRF undulator beamline

1998 ◽  
Vol 5 (3) ◽  
pp. 1064-1066 ◽  
Author(s):  
Luc Ortega ◽  
Fabio Comin ◽  
Vincenzo Formoso ◽  
Andreas Stierle
Keyword(s):  
Synchrotron Radiation ◽  
Trace Element ◽  
Trace Element Analysis ◽  
Element Analysis ◽  
Double Crystal ◽  
X Ray ◽  
Double Crystal Monochromator ◽  
First Results ◽  
Set Up ◽  
Wave Methods

Synchrotron radiation total-reflection X-ray fluorescence (SR-TXRF) has been applied to the impurity analysis of Si wafers using a third-generation synchrotron radiation undulator source. A lower limit of detectability (LLD) for Ni atoms of 17 fg (1.7 × 108 atoms cm−2) has been achieved with an optical set-up based on an Si(111) double-crystal monochromator and a horizontal sample geometry. These first results are very promising for synchrotron radiation trace element analysis since we estimate that it is possible to lower the LLD by a factor of about 25 by employing appropriate optics and detectors. The use of a crystal monochromator opens new possibilities to perform absorption and scattering experiments (NEXAFS and X-ray standing-wave methods) for chemical and structural analysis of ultratrace elements.

scholarly journals Endoscopic Pan/Tilt Camera for Thorax Interventions – Design and first results

2019 ◽  
Vol 5 (1) ◽  
pp. 517-519
Author(s):  
Alexander Mrokon ◽  
Peter P. Pott ◽  
Volker Steger
Keyword(s):  
Minimally Invasive ◽  
Inclination Angle ◽  
Magnetic Circuit ◽  
Mechanical Stability ◽  
Fem Simulation ◽  
Camera System ◽  
Design Changes ◽  
First Results ◽  
Set Up ◽  
Future Work

AbstractMinimally invasive surgery in some cases suffers from a limited view because certain areas are obscured by others. In this paper, a system is described, which can be used in minimally invasive procedures as an addition to a standard endoscope to improve the range of view. Through FEM simulation a magnetic circuit was designed to position the camera head. Subsequently, a camera positioning system was set up that includes an extracorporeal and an intracorporeal unit. The first controls the intracorporeal system. The latter has a camera inclination angle of up to 65° and an additional vertically downward viewing angle when aligned in parallel (inclination angle 0°). The panning angle is 360°. The camera system was evaluated in lab and cadaver trials. It has been found that the size of the intracorporeal system (16 × 10 × 150 mm) represents a major problem. Future work will focus of the reduction of the system’s size, the improvement of the camera image quality, and design changes considering mechanical stability.

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