SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Calibration Systems • Special Equipment • DKD Laboratory • Environmental Testing
THE NEED FOR CONTROLLED SHOCKS
A NEW TYPE OF SHOCK EXCITER ALLOWS TO
APPLY WELL DEFINED MECHANICAL SHOCKS
IMEKO XIX World Congress, Lisbon, September 2009
Dr. Holger Nicklich, Martin Brucke, Michael Mende
SPEKTRA Sound & Vibration
IMEKO XIX World Congress 2009
1
Introduction
Shock Exciters
What do you expect from a
perfect shock exciter?
•
•
•
precise shock amplitude control
very good repeatability
no transverse motion
•
•
pulse width / amplitude independent
arbitrary shape of shock
•
•
•
easy and convenient to operate
allow primary shock calibration
no wear parts (longterm stability)
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Author: Dr. Holger Nicklich, Martin Brucke, Michael Mende
* patent pending DE 10 2008 025 866,
international PCT application planned
IMEKO XIX World Congress 2009
2
Introduction
Shock Exciters
CS18 LS Low Shock system
• 100 m/s2 to 2,000 m/s2
• up to 8 ms pulse width
CS18 LMS Low-Medium Shock
system
• 100 m/s2 to 150,000 m/s2
• pulse width 0.1 ms … 5 ms
CS18 HS High Shock system
• 10,000 m/s² to 1,000,000 m/s²
• typical 50 µs pulse width
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Author: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
3
Introduction
Shock Exciters
CS18 LS Low Shock system
• 100 m/s2 to 2,000 m/s2
• up to 8 ms pulse width
CS18 LMS Low-Medium Shock
system
• 100 m/s2 to 150,000 m/s2
• pulse width 0.1 ms … 5 ms
Anvil
Adjustable Stop
DUT
Barrel
p +/-
Projectile
(Hammer)
Back-to-Back
Reference Sensor
CS18 HS High Shock system
• 10,000 m/s² to 1,000,000 m/s²
• typical 50 µs pulse width
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Author: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
4
Hammer-Anvil Shock Exciters
Amplitude and Pulse Width Control
Hammer - Anvil Shock Exciters
do not allow a very precise control
of the shock amplitude!
• insufficient control of hammer
(kinetic energy )
• Hammer – Anvil impact is not
completely elastically
• wear problems in the contact zone
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
5
Hammer-Anvil Shock Exciters
Amplitude and Pulse Width Control
Hammer - Anvil Shock Exciters do not allow to control
shock amplitude and pulse width independently!
• nonlinear stiffness in contact zone
(
according to Hertz)
• additional nonlinear stiffness from an elastomer layer or
other mitigator on the anvil surface
 the higher the amplitude, the shorter the pulse width
Stiffness
Anvil
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
6
Hammer-Anvil Shock Exciters
Amplitude and Pulse Width Control
A Hopkinson-bar shows even a stronger dependency of
shock amplitude and pulse width!
• the force pulse input causes a longitudinal compression wave
in the bar
• the relationship between force input and acceleration output is
c0 = speed of sound A = sectional area of bar
E = Young’s modulus
• Hopkinson–bar works like a ‘shock amplifier’
 the time derivative makes things even worse
Displacement u(x,t)
a
F
t
MP1
MP 2
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
MP n
t
IMEKO XIX World Congress 2009
7
The HOP-MS Shock Exciter
Design goals
Development of a shock exciter that
is closer to an ideal exciter
• easy and precise control
• very good repeatability of shocks
• shock amplitudes up to some 1,000 gn
• convenient to operate
• primary and secondary calibration
• no wear parts
• low transverse motion
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
8
Overview Shock Exciter
Hopkinson-Bars cover a broad amplitude range
20000000
High Shock Hopkinson-Bar
e.g. SPEKTRA SE-221/222 HOP-HS/VHS
2000000
200000
Acceleration
Acceleration[m/s²]
[m/s²]
Pneumatic Shock Exciter
e.g. SPEKTRA SE-201 PN-LMS
20000
Shock Pendulum
e.g. SPEKTRA SE-210 SP-LS
NEW !
Medium Shock Hopkinson-Bar
SPEKTRA SE-220 HOP-MS
2000
200
20
10
100
1000
10000
Impulse Duration [µs]
SAVIAC Conference October 2009
9
The HOP-MS Shock Exciter
Operating principle
F –Reaction Force
Reaction Mass
F – Input Force
Hopkinson-Bar
Piezoelectric
Actuator
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
DUT
Laservibrometer
(reference standard)
10
The HOP-MS Shock Exciter
Operating principle
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
11
The HOP-MS Shock Exciter
Control
The HOP-MS shock exciter can be
precisely controlled!
• force generation due to elongation
of a piezo actuator simply controlled
by an electrical signal
• simple two-mass oscillator model
fits well with measurements
• a transfer function H(f) [N/V] for the
force input can be determined
• the transfer behavior of the
Hopkinson-bar is also well known
shock output can be controlled
in amplitude and wave form
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
12
The HOP-MS Shock Exciter
Amplitude Control
Wide amplitude range and
good repeatability!
•lowest possible shock amplitude just
limited by noise (actuator, measurement chain)
•20 m/s2 in current type
•maximum shock amplitude limited by
 maximum force of actuator and
 pulse width, due to a(t) ~ dF(t) / dt
 geometry and material of the bar
•40,000 m/s2 in current type
•amplitude repeatability < 0.3%
(conventional Hopkinson-bar 8% -10 %)
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
13
The HOP-MS Shock Exciter
Pulse Width Control
Pulse width and shock amplitude
can be controlled independently!
• maximum pulse width is limited by
length of the bar
• current 2m bar -> 400 µs
• at high shock amplitudes the
exciter is also limited by the
maximum force amplitude of the
actuator (see a(t) ~ dF(t) / dt)
Displacement u(x,t)
a
F
t
MP1
MP 2
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
MP n
t
IMEKO XIX World Congress 2009
14
Shock Calibration
ISO 16063-22 – Signal Processing
Halfsine Shock
Accelerator Signal U [V]
URef
0
UDUT
1
2
3
4
5
6
Time [ms]
Reference
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Author: Dr. Holger Nicklich, Martin Brucke, Michael Mende
DUT
IMEKO XIX World Congress 2009
15
Shock Calibration
Sensitivity
Acceleration
ISO 16063-22 – Dependency on Shock Input
0
10000
20000
Frequency
Spectrum Shock Short
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Author: Dr. Holger Nicklich, Martin Brucke, Michael Mende
Spectrum Shock Long
IMEKO XIX World Congress 2009
30000
40000
Datenreihen4
Accelerometer Sensitivity
16
The HOP-MS Shock Exciter
Shock Shaping
The HOP-MS Exciter allows to shape the
acceleration output in a wide range!
• the electrically controlled piezo actuator
allows a nearly arbitrary force input signal
• the transfer function of the exciter can be
determined
• apply controlled pre-distortion to the input
signal taking the transfer function into
account
 controlled acceleration output with
nearly arbitrary shape is possible
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
17
The HOP-MS Shock Exciter
Shock Shaping
time domain
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
frequency domain
IMEKO XIX World Congress 2009
18
The HOP-MS Shock Exciter
Shock Shaping
time domain
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Authors: Dr. Holger Nicklich, Martin Brucke, Michael Mende
frequency domain
IMEKO XIX World Congress 2009
19
The HOP-MS Shock Exciter
Conclusions
The HOP-MS is a really new type of
shock exciter !
•
it brings a new quality to shock
excitation and measurement
•
the simple electrical control allows
an all automated operation
•
it makes shock calibration and
amplitude linearity checks
quick, convenient and cost saving
•
the exact and independent control
of shock amplitude and shape
opens new application ranges
(e.g. MEMS testing)
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Author: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
20
Acknowledgements
I like to thank all authors for their work on
this project especially
Martin Brucke, who developed the HOP-MS
shock exciter and wrote his doctoral thesis
about this development.
Matthias Woog who spend a lot of work in
the development of the software that controls
this shock exciter and who performed many
experiments that showed its impressive
range of applications.
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Author: Dr. Holger Nicklich, Martin Brucke, Michael Mende
IMEKO XIX World Congress 2009
23
SPEKTRA Schwingungstechnik und Akustik GmbH Dresden
Calibration Systems • Special Equipment • DKD Laboratory • Environmental Testing
Gostritzer Straße 61 - 63
D - 01217 Dresden
phone +49 351 400 24 0
fax
+49 351 400 24 99
[email protected]
www.spektra-dresden.com
IMEKO XIX World Congress 2009
24