votre modèle est en désaccord avec vos mesures de vibration ? un voile levé sur les vibrations...
TRANSCRIPT
Gaëtan Kerschen, Professeur, ULg - Laboratoire de structures et systèmes spatiaux
Jeudi 10 novembre
Votre modèle est en désaccord avec vos mesures de vibration ? Un voile levé sur les vibrations non-linéaires.
Gaëtan Kerschen
Space Structures and Systems Lab.
Aerospace and Mechanical Eng. Dept.
University of Liège
Votre modèle est en désaccord avec vos
mesures de vibration ?
Un voile levé sur les vibrations non-linéaires
2
Aerospace and Mechanical Engineering Dept.
Founded in the 1960s, 25 professors, 100 researchers.
Materials, solid & fracture mechanics, aerodynamics &
aeroelasticity, fluid dynamics, vibrations, space structures,
propulsion, thermodynamics.
Subsonic wind tunnel (1.5m x 2m test section).
Master of Aerospace Engineering (full-English).
3
1960-1980: FEM and
SAMCEF software
F. de Veubeke
1980-2000: flexible multibody
dynamics (MECANO)
M. Géradin
2000-date: 4 Professors active in vibrations,
O. Bruls, J.C. Golinval, G. Dimitradis, GK.
Long-standing Tradition in Vibrations @ ULg
Spin-offs: SAMTECH
Open Engineering
V2i
4
Space Structures and Systems Lab (S3L)
Nonlinear vibrations
Frequency
Energy
Bifurcations
(Aero)space structures
Orbital mechanics &
mission analysis Nanosatellites
5
Outline
The virtual prototyping era & nonlinearities.
Aircraft fly, so what ?
The proposed philosophy.
The F-16 aircraft.
NOLISYS, a two-day-old start-up.
6
Maturity of the Finite Element Method
The vibrations and resonances of complex structures
such as full-scale aircraft and bridges can be effectively
predicted using the finite element method.
Airbus A350WXB
7
The Virtual Prototyping Era
A model can predict the behavior of a structure before the
existence of the first prototype.
Using models, we can access non measurable information
(e.g., stress).
Particular operational conditions (e.g., earthquakes) that are
difficult to reproduce experimentally can be simulated.
Test design (e.g., sensor and actuator placement).
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Typically, Linear Behavior Is Assumed
A X
B Y
A+B X+Y LIN
LIN
LIN
Output
Input
No unpleasant surprise
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Nonlinear System ?
A X
B Y
A+B ??? NL
NL
NL
Output
Input
Nonlinear
Linear
Weak
impact
Strong
impact
10
Bolts, joints and gaps Elastomers and composites
Friction and contact Large amplitudes
Common Types of Nonlinearities
11
Outline
The virtual prototyping era & nonlinearities.
Aircraft fly, so what ?
The proposed philosophy.
The F-16 aircraft.
NOLISYS, a two-day-old start-up.
13
Satellite Fly But …
5 20 30 70-100
0
100
Accel.
Sweep frequency (Hz)
Acc.
(m/s2)
0.1 g
1 g excitation
Tests @ Airbus Defence and
Space with Siemens and S3L
Impact: « unpleasant » surprise, troubleshooting needed.
Dangerous resonance
popping up out of the blue
15
Nonlinearities of Airbus A400M Revealed During Tests
Failure of commercial linear software (Siemens-LMS):
…during the A400M GVT, highly force-dependent resonances were
systematically fitted by means of two structural modes…
Impact: Nonlinearities slowed down aircraft certification.
17
You Are Nonlinear !
Load
Extension Toe region:
normal range Linear Yield
Human cadaveric
anterior cruciate
ligament in knee
joint (Dr. Ziv,
MAE, Buffalo)
18
Outline
The virtual prototyping era & nonlinearities.
Aircraft fly, so what ?
The proposed philosophy.
The F-16 aircraft.
NOLISYS, a two-day-old start-up.
19
Our Philosophy: From Measurements to Design
IDENTIFY MEASURE
VIBRATION
MEASUREMENTS
Identify nonlinear
connections early on
UNDERSTAND
DESIGN HYBRID
MODELING
LINEAR FINITE
ELEMENT MODEL
Compute nonlinear
features and responses
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More than 15 Years of Developments @ S3L
MEASURE
VIBRATION
MEASUREMENTS
Dedicated,
early, tests
IDENTIFY
Detection
Location
Visualization
Exp. modeling
UNDERSTAND
Nonlinear
modes
Nonlinear freq.
responses
DESIGN
Optimization
LINEAR FINITE
ELEMENT MODEL
HYBRID
MODELING
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1. Yes or No ?
2. What ? Where ? How ?
3. How much ?
xxxxxfnl ,sin,),( 3
?
333 3,2.1,1.0),( xxxxxfnl ?
We Seek an Experimental Model for the Nonlinearity
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The NI2D Software Integrates These Methods
Today the only software dedicated to the experimental
& numerical analysis of nonlinear vibrations.
23
The virtual prototyping era & nonlinearities.
Aircraft fly, so what ?
The proposed philosophy.
The F-16 aircraft.
NOLISYS, a two-day-old start-up.
Outline of the Presentation
24
Testing of a Full-Scale F-16 Aircraft
Belgian airforce base.
Collaboration with
Siemens LMS.
Right missile Connection with the wing
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Nonlinearity Has a Beneficial Effect Here
Frequency (Hz)
4 2 6
-40
-60
-80 8 10
-20
10 N RMS
100 N RMS
Output
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The Observed Nonlinearities
-4 -3 -2 -1 0 1 2 3 4
x 10-4
-5
-4
-3
-2
-1
0
1
2
3
4
5Force level: 67 N rms
Relative displacement (m)
- A
ccele
ration (
m/s
2)
-0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5Force level: 67 N rms
Relative velocity (m/s)
- A
ccele
ration (
m/s
2)
Right missile Connection with the wing
Friction
Joint
opening
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Linear main structure =
fairly easy to model
numerically.
Nonlinear component =
difficult to model numerically.
Data-Driven and Computer-Aided Models Integrated
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The virtual prototyping era & nonlinearities.
Aircraft fly, so what ?
Nonlinearities & the proposed philosophy.
The F-16 aircraft.
NOLISYS, a two-day-old start-up.
Outline of the Presentation
32
The NOLISYS Spin-Off Company
April 2016: First Spin-Off from the Walloon Region
(with support from Siemens, V2i & GDTECH)
Nov. 2016: SPRL (T. Detroux, managing director).
≤ 2018: Creation of a SA.
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Training Activities
With international industrial attendees: Airbus Toulouse, Airbus Defence and
Space, Bruel & Kjaer, US Air Force, MAG-IAS, Sandia National Labs.
1st-3rd ed., Liège, 2015-2016
4th ed., Los Angeles, 2017
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Concluding Remarks
Nonlinearity is pervasive in engineering structures:
Main economic benefits:
► Reduce time-to-market.
► Avoid painful troubleshooting.
► Better performance by exploiting nonlinearity early on.
► Limit performance (F-16).
► Slow down the design cycle and testing campaigns (A400M).
► Hinder product certification.
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The Quest for Lighter and Lighter Structures
No resonances.
Early 1900s
Dynamic design (LIN) Dynamic design (NL) Static design
Resonances under control.
No nonlinearity
HEAVY
STRUCTURES
Today Tomorrow
Resonances & nonlinearity
under control.
LIGHT
STRUCTURES
ULTRA-LIGHT
STRUCTURES
Performance Environment