Advanced Modal Seminar - Siemens PLM Community · PDF fileAdvanced Modal Seminar Brasil, Februari 2017 ... Experimental Modal Analysis vs. Finite Element Modal Analysis •Experimental

Advanced Modal Seminar
Brasil, Februari 2017Tom Knechten & Mostapha Choukri
Realize innovation.Unrestricted Siemens AG 20XX

Agenda
Day 1 Duration
08:30 Registration 30mins
09:00 Introdution to SIMCENTER 30mins
09:30 Modal Analysis Theory overview Modal Parameters
SDOF
MDOF
2hrs
11:30 Tips & Tricks accurate FRF measurements
Modal Validation techniques
1hr 30mins
13:00 Lunch 1hr
14:00 Modal Testing Techniques Impulse Excitation
Random Excitation
Stepped/Swept sine Excitation
1hr 30mins
15:30 Interactive section Questions and answers
Demonstrations
1hr 30mins
Day 2 Duration
08:30 Advanced Modal Analysis Techniques
Operational Modal Analysis
Rigid Body Properties
Modification Prediction
1hr 30mins
10:00 Coffee break 15mins
10:15 New developments in Modal Analysis
Order Based Modal Analysis
Strain Based Modal Analysis
Acoustic Modal Analysis
1hr 15mins
11:30 Plant tour 1hr 30 min
13:00 Lunch 1hr
14:00 Pre-test, correlation and updating 1hr 30 mins

Modal Testing Theory
recap
Advanced Modal Seminar Brasil, Februari 2017
Tom Knechten, Mostapha Choukri
Realize innovation.Restricted Siemens AG 2016

Unrestricted Siemens AG 2016
Siemens PLM Software
Agenda
Modal Analysis Theory overview
Structural dynamics and modal analysis
Use of modal parameters
Modal Validation techniques
Tips & Tricks accurate FRF measurements
Excitation and response
FRF measurements
Parameter estimation

Introduction

Restricted Siemens AG 2013 All rights reserved.
Why is this happening?
Wind interaction
Aero Elastic interaction
People interaction
Collapsing bridge
Flutter
Wobbling bridge

Receiver
Road
Wheel & TireSteering Wheel
Shake
Seat Vibration
Rearview mirror
vibration
Engine
Experimental Modal Analysis
Understanding the Dynamic Properties of Structures
X =
Gearbox and
Transmission
Turbomachinery
Accessories
RotorCockpit vibration &
noise
Cabin comfort
Noise at Drivers &
Passengers Ears
Structural Integrity
Environmental
sources
Source System Transfer

Systematic approach to noise & vibration testing
The source transfer - receiver approach
Receiver
Source
Response:
noise
vibrations=
X
critical
dynamics
=
X
critical
loads
=
X
worst case
scenario
Operating loads:
structural
acoustic
System Transfer
System characteristics:
structural
acoustic
!

9
Why identify structural resonance?
Define your pains
Low
throughput
Pa
ins
Wh
y ?
Low quality of
the final
product
Increasing speed causes
Component breakdown
Machine failure
Poor precision
Inconsistent product quality
Excessive vibration issues
Too low machinary performance
Noise & vibration problem
Steerling wheel shake
Driver seat vibration
Noise at Drivers & Passengers
Ears
Drive and ride comfort
Certify a plane
Structural integrity
Ground vibration testing
Flight test
Flutter phenomena
Safety

Structural Dynamics
and Modal Analysis

Structural Dynamics Modelling
Structural dynamics modelling
Relating force inputs to displacement-velocity
acceleration outputs
Modal Analysis
Structural dynamics modelling using modal parameters
Single Degree of Freedom System
ground
m
ck
x(t)
f(t) ( )mx cx kx f t
nk
m
2 n
c
m

SDOF (Single degree of freedom) system
0 2 4 6 8 10 12 14 16 18 2010
-2
10-1
100 Frequency Response Function
Frequency Hz
Lo
g-M
agnit
ud
e
0 2 4 6 8 10 12 14 16 18 20-200
-150
-100
-50
0
Frequency Hz
Phas
e
damping controlled region
stiffness controlled region
mass controlled region
xf H
2
( ) 1( )
( )
xH
f m cj k
System Transfer ReceiverX =Source
ground
m
ck
x(t)
f(t)
The simplest dynamic system

2 1
( ) ( ) ( )
( ) [ ]
X H F
H M j C K
2( ) ( ) ( )M j C K X F
How to identify structural resonance?
Multiple Degree of Freedom System
Time-domain equation of motion
Fourier transform
Frequency Response Function
( ) ( ) ( ) ( )M x t C x t K x t f t
gro
un
d
m1c1
k1
f1(t)
m2 mn gro
un
d
kn+1k2
c2 cn+1
f2(t)fn(t)
x1(t)x2(t)
xn(t)

Modal Analysis
The Formulas
Residues and poles
Modal parameters
Eigenfrequencies
Damping ratios
Mode shapes
Modal scaling factors
*
*1
( )n
ii
i i i
AAH
j j
{ } Ti i i iA Q
HF X
Input System Output
2 1
( ) ( ) ( )
( ) [ ]
X H F
H M j C K
i
i
{ }i
iQ
No
ntr
ivia
l m
ath
em
ati
cs
iiiiii j 2* 1,

15
*
*1
( )n
ii
i i i
AAH
j j
Frequency Response Functions (FRF) &
Impulse Response Functions (IRF)
FRF matrix
1 element
IRF matrix
1 element*
, ,
*1
( )n
pq i pq i
pq
i i i
A AH
j j
( )pqH j
( )pqH j
*
*
1
( ) e en
i ii i
i
t th t A A
**
, ,
1
( ) e en
i ipq pq i pq i
i
t th t A A
0.00 80.00 Hz
10.0e-6
0.10
Log
(g/N
)
0.00 80.00 LinearHz
0.00 80.00 Hz
-180.00
180.00
Phase
0.00 6.00 s
-1.07
0.91
Real
(g/N
)
Inverse
Fourier
transform
Frequency
domain
Time
domain

Modal Analysis
The Physics
Deformation at certain moment =
linear combination of mode shapes
Linear combination factors depend
on input forces, frequency, damping
and mode shape at input locations
Vibration
Response
Mode shapes
+ + ++ ...
a1x x x x
a2 a3 a4

Modal Analysis
Mode of Vibration = Resonance of the Structure
Mode shape
Not only rigid body movements...
0.00 50.00 Linear
Hz
0.00
1.20e-3
Am
plit
ude
(g/N
)0.00 50.00 Linear
Hz
0.00 50.00 Hz
-180.00
180.00 P
hase
0.00 50.00 Linear
Hz
0.00
1.20e-3
Am
plit
ude
(g/N
)
0.00 50.00 Linear
Hz
0.00 50.00 Hz
-180.00
180.00
Phase

Experimental Modal Analysis vs.
Finite Element Modal Analysis
Experimental
Requires prototype
Very fast (1-5 days)
Very accurate for frequency
More reliable for damping
Limited number of points
Numerical
Requires FE model
Many days/weeks
Fast alternative evaluation
A lot of model uncertainties
(joints, damping, )
High number of points
( )H , ,{ },i i i iQ , ,M C K , ,{ },i i i iQ

Correlation with and Updating of
Finite Element Models
FEM
GVT
FEM
GVT
GVT
FEM
Eigenfrequency correlation
+ 5%
- 5%
Airbus A330 MRTT

Experimental Modal Analysis
5. Use modal parameters
Troubleshooting
Simulation and prediction
Design optimisation
Diagnostics and health monitoring
Finite Element model
verification/improvement
Hybrid system model building

Documents

Advanced Modal Seminar - Siemens PLM Community · PDF fileAdvanced Modal Seminar Brasil, Februari 2017 ... Experimental Modal Analysis vs. Finite Element Modal Analysis •Experimental