ISO 16063-22:2005

INTERNATIONAL ISO
STANDARD 16063-22
First edition
2005-06-01

Methods for the calibration of vibration
and shock transducers —
Part 22:
Shock calibration by comparison to
a reference transducer
Méthodes pour l'étalonnage des transducteurs de vibrations
et de chocs —
Partie 22: Étalonnage de chocs par comparaison à un transducteur
de référence




Reference number
ISO 16063-22:2005(E)
©
ISO 2005

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ISO 16063-22:2005(E)
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ISO 16063-22:2005(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 2
4 Uncertainty of measurement. 2
5 Apparatus. 3
5.1 General considerations. 3
2 2
5.2 Anvil shock calibrators (100 m/s to 100 km/s ) . 3
5.3 Hopkinson bar shock calibrators . 8
5.4 Oscilloscope. 9
5.5 Waveform recorder with computer interface . 9
5.6 Computer with data-processing capability . 10
5.7 Filters. 10
5.8 Other requirements. 10
6 Ambient conditions. 10
7 Preferred accelerations and pulse durations.10
8 Method. 11
8.1 Test procedure. 11
8.2 Data acquisition. 11
8.3 Signal processing. 11
9 Reporting the calibration results. 15
Annex A (normative) Expression of uncertainty of measurement in calibration . 16
Annex B (informative) Uncertainty examples — Expression of uncertainty of measurement in
calibration . 19
Bibliography . 22

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ISO 16063-22:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 16063-22 was prepared by Technical Committee ISO/TC 108, Mechanical vibration and shock,
Subcommittee SC 3, Use and calibration of vibration and shock measuring instruments.
This first edition cancels and replaces ISO 5347-4:1993, which has been technically revised.
ISO 16063 consists of the following parts, under the general title Methods for the calibration of vibration and
shock transducers:
 Part 1: Basic concepts
 Part 11: Primary vibration calibration by laser interferometry
 Part 12: Primary vibration calibration by the reciprocity method
 Part 13: Primary shock calibration using laser interferometry
 Part 15: Primary angular vibration calibration by laser interferometry
 Part 21: Vibration calibration by comparison to a reference transducer
 Part 22: Shock calibration by comparison to a reference transducer
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INTERNATIONAL STANDARD ISO 16063-22:2005(E)

Methods for the calibration of vibration and shock
transducers —
Part 22:
Shock calibration by comparison to a reference transducer
1 Scope
This part of ISO 16063 specifies the instrumentation and procedures to be used for secondary shock
calibration of rectilinear transducers, using a reference acceleration, velocity or force measurement for the
1)
time-dependent shock. The methods are applicable in a shock pulse duration range of 0,05 ms to 8,0 ms,
2 2
and a dynamic range (peak value) of 100 m/s to 100 km/s (time-dependent). The methods allow the
transducer shock sensitivity (i.e. the relationship between the peak values of the transducer output quantity
and the acceleration) to be obtained.
These methods are not intended for the calibration of dynamic force transducers used in modal analysis.
NOTE 1 This part of ISO 16063 is aimed at users engaged in shock measurements requiring traceability as stated in
ISO 9001 and ISO/IEC 17025.
NOTE 2 The methods specified in this part of ISO 16063 are based on the measurement of the time history of the
acceleration. These methods fundamentally deviate from another shock calibration method that is based on the principle
of the change in velocity, described in ISO 16063-1. The shock sensitivity therefore differs fundamentally from the shock
calibration factor obtained by the latter method, but is in compliance with the shock sensitivity stated in ISO 16063-13.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 2041, Vibration and shock — Vocabulary
ISO 5347-22, Methods for the calibration of vibration and shock pick-ups — Part 22: Accelerometer resonance
2)
testing — General methods
ISO 16063-1:1998, Methods for the calibration of vibration and shock transducers — Part 1: Basic concepts
ISO 18431-2, Mechanical vibration and shock — Signal processing — Part 2: Time domain windows for
Fourier Transform analysis

1) In exceptional cases, shorter or longer shock pulse durations are possible.
2) Under revision to become a part of ISO 16063.
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ISO 16063-22:2005(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2041 and the following apply.
3.1
peak value
maximum value of the magnitude or absolute value of the shock pulse
4 Uncertainty of measurement
The limits of the uncertainty of shock sensitivity measurement are as shown in Table 1.
Table 1 — Uncertainty reference conditions for secondary shock calibration
Acceleration peak
Minimum pulse
a a,b
magnitude duration
Shock calibrator apparatus Uncertainty limit
2
km/s ms
Pendulum 1,5 3 5 %
Dropball 100 0,100 5 %
Pneumatically operated piston 100 0,100 5 %
c c
Hopkinson bar with velocity comparison 100 0,050 10 %
c c
Hopkinson bar with acceleration comparison 100 0,050 6 %
c c
Split Hopkinson bar with force comparison 100 0,050 10 %
a
Variations in peak values and duration = ±10 %.
b
Pulse duration is measured at 10 % of the peak value (see Clause 7).
c
Larger accelerations (peak values) and shorter pulse durations are possible but without reference to primary methodologies.

The uncertainty of measurement is expressed as the expanded relative measurement uncertainty in
accordance with ISO 16063-1 (briefly referred to as “uncertainty”). The specified uncertainties are based on a
coverage factor k = 2 that is a coverage probability of about 95 %.
The uncertainty specifications of Table 1 can be achieved as long as the spectral energy produced by the
excitation of any mode of resonance inherent in the transducer or shock machine structure during calibration
is small relative to the spectral energy contained in the frequency range of calibration. The transducer
resonance testing shall be performed in accordance with ISO 5347-22.
NOTE For the calibration of transducers of high accuracy (e.g. reference transducers) and if great care is taken to
keep all uncertainty components small enough to comply with the specifications (see uncertainty budgets in Annex A),
smaller uncertainties than stated in Table 1 may be achievable. For the pendulum shock calibrator, the dropball shock
calibrator and the pneumatically operated piston shock calibrator, an uncertainty of 1 % has been obtained in an
2 2 [1]
interlaboratory comparison covering acceleration peak values from 200 m/s to 2 000 m/s .
The acceleration peak magnitude may be expressed in terms of the standard acceleration due to gravity,
2 2
symbol g (1 g = 9,806 65 m/s ; 1,5 km/s ≈ 150 g ).
n n n
The shortest shock duration applicable to a transducer according to the manufacturer’s specification shall be
taken into account to avoid increasing the measurement uncertainty and damaging or destroying the
transducer.
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ISO 16063-22:2005(E)
5 Apparatus
5.1 General considerations
All surfaces on which transducers (the reference or the transducer under test) are mounted shall be polished,
flat and clean. The surface on which the transducer is to be mounted shall have a roughness value, expressed
as the arithmetical mean deviation, Ra, of less than 1 µm. The flatness shall be such that the surface is
contained between two parallel planes 5 µm apart, over the area corresponding to the maximum mounting
surface of any transducer to be calibrated. The drilled and tapped hole for connecting the transducer shall
have a perpendicularity tolerance to the surface of less than 10 µm; i.e. the centreline of the hole shall be
contained in a cylindrical zone of 10 µm diameter and a height equal to the hole depth. Appropriate screw and
bolt torque may be found in numerous references and are chosen according to the mounting surface material.
The recommendations of the transducer manufacturer shall be followed in all cases.
2 2
5.2 Anvil shock calibrators (100 m/s to 100 km/s )
5.2.1 General considerations
This clause gives recommended specifications for the anvil shock calibrators to obtain the uncertainties of
Clause 4. When back-to-back calibrations are performed with the dropball shock calibrator or the
pneumatically operated piston shock calibrator, it is recommended that the transducer under test be mounted
directly on top of the reference transducer as shown in Figure 1. This mounting is not recommended for
pendulum shock calibrators, see 5.2.2 and Figure 3. For best accuracy, test transducers and mounting fixtures
should not have dimensions or masses significantly greater than that of the reference transducer because the
sensitivity and frequency response of the reference transducer will vary slightly depending on the amount of
mass attached. For all methods, the natural period of the test transducer, equal to the inverse of the
resonance frequency, shall be less than 0,2 times the half-sine pulse duration of the applied shock pulse to
eliminate excessive overshoot and “ringing” due to resonance excitation.

Key
1 test transducer
2 reference transducer
3 test mass
4 anvil
Figure 1 — Recommended mounting of transducers, anvil and test masses
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ISO 16063-22:2005(E)
5.2.2 Pendulum shock calibrator
The pendulum shock calibrator provides an assessment of the shock sensitivity and magnitude linearity for
transducers and a means of calibrating large quantities of transducers. Comparison calibrations are performed
2 2
at accelerations ranging from 100 m/s to 1 500 m/s (10 g to 150 g ) at half-sine pulse durations (measured
n n
at 10 % magnitude) from 3 ms to 8 ms. A schematic diagram of the pendulum shock calibrator is shown in
2
Figure 2. The shock pulse duration, T, is dependent on the acceleration peak value, i.e. 3 ms at 1 500 m/s
2
and 8 ms at 100 m/s . Amplitude linearity may be measured over 4 to 7 impacts of the pendulum system, or
with a number of single shock pulses at different acceleration magnitudes.
The pendulum shock calibrator consists of a rigid frame, a hammer pendulum and an anvil pendulum. Typical
dimensions for the frame are approximately 500 mm by 500 mm for the square base plate and 780 mm height.
The mass of the whole construction is approximately 60 kg. The length of anvil pendulum is approximately
400 mm. Shifting the hammer pendulum to the desired angular displacement and dropping it can excite an
impact from the hammer pendulum to the anvil pendulum. An angular scale, graduated in degrees, is provided
for determining the angular displacement of the hammer pendulum. The maximum velocity change during the
impact phase is less than 3 m/s. A reference transducer and a test transducer are mounted on the pendulum
as shown in Figure 3. A scale, graduated in degrees, is provided for angular displacement of the hammer
pendulum. Both pendulums have approximately the same moment of inertia to give a series of impacts with
decreasing amplitude. A rubber pad between the two pendulums transmits the impact with a known pulse
shape from one pendulum to the other. The hardness of the rubber pad determines the pulse shape and
duration as well as the number of applicable impacts. To create a haversine pulse shape, typical butadiene
rubber pad specifications are 8 mm thickness and 56 Shore A hardness. The test and reference transducers
are located at the nodal point for the first axial mode of the anvil pendulum to prevent structural vibrations
from contaminating the data. It is recommended that the centre of gravity for the seismic mass of the
transducer under test be aligned with the sensitive axis of the reference transducer at the anvil pendulum by
[15]
means of a mounting stud or other optional mounting adapters .

Key
1 graduated scale with adjustable end stop
2 hammer pendulum
3 rubber pad
4 reference transducer
5 test transducer
6 anvil pendulum
Figure 2 — Example of a pendulum shock calibrator for transducer
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ISO 16063-22:2005(E)

Key
1 reference and measurement surface used for primary calibration
2 anvil pendulum
3 test transducer
4 reference transducer
5 butadiene rubber
6 hammer pendulum
Figure 3 — Correct mounting of transducers and selection of the reference surface for the reference
transducer for pendulum shock calibrator
5.2.3 Dropball shock calibrator
A dropball shock calibrator uses a reference transducer mounted back-to-back with the test transducer on a
2 2
steel anvil as shown in Figure 4. Shock peak magnitudes of 100 m/s to 100 km/s with pulse durations of
0,100 ms to 10 ms are created with the dropball. The assembly is inserted inside the tube of the dropball
apparatus with the transducers located on the bottom of the anvil. The anvil is held in place inside the tube
magnetically. A vacuum chuck is used to position and release a steel ball bearing located on the top of the
tube of the dropball apparatus, such that the ball strikes the centre of the anvil located inside the tube upon
impact. Upon impacting the anvil, the ball creates a mechanical shock pulse and causes the anvil to fall freely
into a foam rubber catch mechanism located below the magnetic chuck inside the tube of the calibration
apparatus. The peak amplitude and duration of the shock pulse created by this collision can be controlled by
[2]
varying the diameter and mass of the ball , and by varying the amount of damping provided by the material
added to the impact surface of the anvil.
The dropball apparatus is used to determine sensitivity as a function of either the peak acceleration magnitude
[3]
(g ) or frequency . Ideally, parameters should be varied to produce pulses that result in significant spectral
n
energy in the frequency range of 5 kHz to 10 kHz, independent of peak amplitude. For example, the diameter
of the anvils that produce pulses having peak acceleration amplitudes in the range of 100 g to 1 000 g is
n n
less than 25 mm. The purpose of the plunger is to prevent multiple collisions of the relatively small-diameter
balls with the anvil after the initial impact. The use of small balls with a small-sized anvil to produce pulses has
two advantages. First, the decrease in the mass of the anvil reduces the risk of damaging the transducers
when the anvil impacts the catch mechanism. Secondly, the reduction in the size of the anvil increases the
frequencies of its natural modes of resonance. The second factor is important in the determination of peak
amplitudes in the time domain, since anvil resonance can significantly modulate the envelope of the
[3]
mechanical shock pulse .
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ISO 16063-22:2005(E)

Key
1 vacuum chuck
2 steel ball bearing
3 plunger (optional)
4 magnetic chuck
5 anvil
6 transducers
7 catch mechanism
Figure 4 — Example of a dropball shock calibrator for transducer
5.2.4 Pneumatically operated piston shock calibrator
An upward moving pneumatically operated piston provides a simple, controllable and repeatable means of
[4]
secondary shock calibration of transducers and is shown schematically in Figure 5 . Shock peak magnitudes
2 2
of 200 m/s to 100 km/s (20 g to 10 000 g ) at half-sine pulse durations from 100 µs to 3 ms, respectively,
n n
are created by the impact of a steel projectile on an anvil. Typical anvil materials are steel and aluminium. A
reference transducer and a test transducer are mounted back-to-back on the anvil. A pressure regulator
controls the pressure on the piston. A valve releases the pressure and provides precise control of the piston.
When the impact occurs, the anvil lifts off a rubber mount, flies a short distance, and is stopped by a
cushioned restraint. The piston is captive within a barrel. A wide range of pulse amplitudes and durations is
created with pressure control and combinations of anvils, additional masses, and pad thickness.
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ISO 16063-22:2005(E)


Key Key
1 cushioned restraint 1 anvil
2 transducer under test and reference transducer 2 rubber pad
3 optional test mass 3 felt pad
4 anvil and pad
5 piston
6 barrel
7 valve
8 pressure regulator
9 pressurized air source
a) Shock calibrator b) Anvil and pad
Figure 5 — Schematic diagram for an upwardly moving pneumatically operated piston
shock calibrator
Pads may be torn by high projectile velocity and large additional masses. Damaged pads create non-
repeatable pulses and potentially, excessively large amplitudes. Pads shall always be inspected before use.
Damaged padding, particularly if it allows metal-to-metal impact between the projectile and anvil, can generate
potentially damaging accelerations with nearly any drive pressure.
The characteristics of a shock pulse in general are determined by
a) the velocity of the projectile,
b) the mass of the target (anvil and transducer assembly) and, most critically,
c) the deformation of material between them.
Projectile velocity is approximately proportional to the drive pressure. Anvil velocity (the area under the
acceleration curve) is affected by the ratio of the target mass to the projectile mass. Target mass is the sum of
the anvil mass, supplemental mass, any additional mounting fixture mass, and the masses of the standard
reference and test transducer. The more flexible the material at the point of impact, the longer the duration of
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ISO 16063-22:2005(E)
the pulse. For a given velocity that results from the impact, the product of the acceleration amplitude and
pulse duration is approximately a constant. A thin pad would provide a short high-amplitude pulse, and thicker
pad on the same anvil would provide a longer pulse of lower amplitude. The area under the curves of the two
[4]
pulses would be approximately equal .
5.3 Hopkinson bar shock calibrators
5.3.1 General

2
Hopkinson bar shock calibrators have operational ranges of high accelerations (peak values 1 km/s to
2
2 000 km/s ) which may be used to evaluate the performance of transducers. This part of ISO 16063 specifies

2 2
the range from 100 m/s to 100 km/s , which has reference to primary methodologies (see ISO 16063-13 for
details).
A Hopkinson bar is generally defined as a long slender bar with a length-to-diameter ratio greater than 10. A
length-to-diameter ratio of approximately 100 produces excellent results for the methods in this section. A
Hopkinson bar calibrator may be instrumented with a reference measurement of either strain gauges or a
laser doppler vibrometer (LDV). Either velocity or acceleration comparisons may be made between the
reference measurement and the transducer under test. A split Hopkinson bar calibrator compares a reference
acceleration derived from a force measurement to the transducer under test. All Hopkinson bar calibrators
2
may be used to evaluate the performance of transducers for peak acceleration values up to 2 000 km/s . The
[5,6]
theory of stress wave propagation in a Hopkinson bar is well documented in the literature .
To provide traceability to primary shock standards, a reference transducer calibrated by primary methods shall
be used to verify the uncertainty of reference transducers for Hopkinson bar shock calibrators.
5.3.2 Hopkinson bar shock calibrator by comparison in terms of velocity or acceleration
The test transducer may be calibrated in terms of velocity by comparing the integrated output of the
[7, 8]
transducer with either strain gauges or a laser doppler vibrometer . The test transducer may also be
calibrated in terms of acceleration by comparing the output of the transducer with the derivative of the output
[9, 10]
of either strain gauges or a laser doppler vibrometer . A schematic diagram of the Hopkinson bar shock
calibrator is shown in Figure 6. Details of Hopkinson bar calibration with a transfer standard are given in
Reference [9].

Key
1 projectile
2 pulse shaper
3 Hopkinson bar
4 strain gauge for reference measurement
5 accelerometer being calibrated
6 initial velocity for projectile, v

o
7 laser reference measurement
Figure 6 — Schematic diagram of a Hopkinson bar shock calibrator
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ISO 16063-22:2005(E)
5.3.3 Split-Hopkinson bar shock calibrator by comparison with a force transducer
The split-Hopkinson bar calibrator is a comparison of acceleration without integrating the transducer output or
taking the derivative of a strain measurement. Figure 7 is a diagram of an aluminium split-Hopkinson bar
[11, 12] [7-10]
apparatus with length-to-diameter ratio for the first bar greater than 10 . The techniques in 5.3.2 use
the same apparatus, but the transducer is mounted directly to the end of the bar in place of the split
configuration. A 0,254 mm thick, 19,0 mm diameter X-cut quartz gauge is bonded to one side of the second
bar and the transducer for calibration is on the opposite face of the second bar.
Provided that the rise time of the incident stress pulse created by projectile impact is sufficiently long and the
steel disk (second bar) length is sufficiently short, the response of the second bar may be approximated as
[11]
rigid body motion for steel and tungsten disks . The rigid body acceleration, a, of the steel disk is calculated
using the quartz gage force measurement, F, and Newton's Second Law, F = ma, where m is the mass of the
flyaway with the transducer under test, and compared to the acceleration measured by the transducer under
test. A vacuum collar is also used to keep the steel disk in intimate contact with the incident bar. Details of the
certification for the split-Hopkinson bar configuration are given in Reference [13].

Key
1 projectile
2 pulse shaper
3 first Hopkinson bar
4 strain gauge for incident wave measurement
5 quartz reference measurement (0,254 mm thick)
6 steel disk or second bar (12,7 mm long)
7 transducer being calibrated
8 initial velocity for projectile, v
o
Figure 7 — Example of a split-Hopkinson bar calibrator
5.4 Oscilloscope
An oscilloscope having two or more channels shall be provided for checking the waveforms of the acceleration
signals, with a minimum frequency range from d.c. to 1 MHz.
5.5 Waveform recorder with computer interface
A waveform recorder with computer interface capable of analog-to-digital conversion and storage of the two
acceleration responses shall be provided. Alternatively, an A/D converter card within the computer may be
used. The resolution, the sampling rate and the memory shall be sufficient for calibration in the intended
dynamic range with the uncertainty specified in Annex A. A resolution of greater than or equal to 10 bits,
preferably 12 bits, is used for the transducer output.
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ISO 16063-22:2005(E)
5.6 Computer with data-processing capability
A computer with data-processing programs or an analyser needed by the different shock calibrators used in
this part of ISO 16063 shall be provided.
5.7 Filters
Analog filters, applied to the acceleration signals to avoid aliasing and/or to sup
...