ISO 16063-31:2009

INTERNATIONAL ISO
STANDARD 16063-31
First edition
2009-08-15
Methods for the calibration of vibration
and shock transducers —
Part 31:
Testing of transverse vibration sensitivity
Méthodes pour l'étalonnage des transducteurs de vibrations et de
chocs —
Partie 31: Essai de sensibilité aux vibrations transversales

Reference number
©
ISO 2009
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©  ISO 2009
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ii © ISO 2009 – All rights reserved

Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Uncertainty considerations .2
4 Determination of transverse sensitivity using a single-axis vibration generator.2
4.1 Apparatus.2
4.2 Method.2
4.2.1 Test procedure.2
4.2.2 Expression of results.3
5 Determination of the transverse sensitivity using a vibration generator with turntable .4
5.1 Apparatus.4
5.2 Method.6
5.3 Expression of results.6
6 Determination of transverse sensitivity using a test system with X- and Y-vibration
generators .6
6.1 Apparatus.6
6.2 Method and expression of results .9
7 Determination of the transverse sensitivity using a tri-axial vibration generator.11
7.1 Apparatus.11
7.2 Method and expression of results .14
8 Equipment for measuring of the input and output signals of the transducer to be tested .15
9 Preferred amplitudes and frequencies.15
Annex A (normative) Definition of transverse sensitivity.16
Bibliography.18

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 16063-31 was prepared by Technical Committee ISO/TC 108, Mechanical vibration, shock and condition
monitoring, Subcommittee SC 3, Use and calibration of vibration and shock measuring instruments.
This first edition cancels and replaces ISO 5347-11:1993.
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
⎯ Part 31: Testing of transverse vibration sensitivity
⎯ Part 41: Calibration of laser vibrometers
The following parts are planned:
⎯ Part 23: Angular vibration calibration by comparison to reference transducers
1)
⎯ Part 32: Resonance testing
⎯ Part 42: Calibration of seismometers

1) Revision of ISO 5347-14:1993 and ISO 5347-22:1997.
iv © ISO 2009 – All rights reserved

INTERNATIONAL STANDARD ISO 16063-31:2009(E)

Methods for the calibration of vibration and shock
transducers —
Part 31:
Testing of transverse vibration sensitivity
1 Scope
This part of ISO 16063 specifies details of the instrumentation and methods to be used for transverse vibration
sensitivity testing. It applies to rectilinear velocity and acceleration transducers.
The methods and procedures specified in this part of ISO 16063 allow the determination of the sensitivity of a
transducer to vibration in the plane perpendicular to its geometric axis of sensitivity (see Annex A). Because
the magnitude of this transverse sensitivity can vary with the direction of the applied vibration, the various
methods determine the maximum value. Using that value, the ratio of the transverse sensitivity to the
sensitivity on the geometric axis of the transducer can be calculated. In addition, the angle at which the
maximum transverse sensitivity occurs can be determined.
The methods and techniques specified can be applied without re-mounting the transducer away from its
mounting surface during the test, thus avoiding significant uncertainties often encountered in methods which
require repeated mounting. The different methods specified use a single-axis vibration exciter, a two-axis
vibration exciter or a tri-axial vibration exciter. Tri-axial vibration excitation allows the transverse sensitivity and
the sensitivity on the geometric axis to be determined simultaneously, thus simulating application conditions
where the transducer is exposed to multi-axial vibration.
NOTE In accelerometer designs using a bending beam, the transverse sensitivity measured without any vibration
acting on the geometric axis of sensitivity of the accelerometer may considerably differ from the transverse sensitivity
measured in the presence of a vibration acting on the geometric axis of sensitivity (i.e. when the bending beam is
deflected by a vibration to be measured).
This part of ISO 16063 is applicable to a frequency range from 1 Hz to 5 kHz and for a dynamic range from
2 2
1 m/s to 1 000 m/s (frequency dependent) and from 1 mm/s to 1 m/s (frequency dependent). Although
among all the systems specified it is possible to achieve these ranges, generally each has limitations
permitting its use in much smaller ranges.
The methods specified are by comparison both to a reference transducer and to a laser interferometer.
The methods specified allow an expanded uncertainty of the transverse sensitivity (coverage factor k = 2) of
0,1 % or less to be achieved, if the expanded uncertainty is expressed as a percentage of the sensitivity of the
test transducer in its sensitive axis.
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 266, Acoustics — Preferred frequencies
ISO 16063-1:1998, Methods for the calibration of vibration and shock transducers: Part 1: Basic concepts
3 Uncertainty considerations
An expanded uncertainty of 0,1 % (see Clause 1) means, for the example of a transverse sensitivity of 1 %,
that the measured value lies within the interval of 0,9 % to 1,1 %.
All users of this part of ISO 16063 are expected to assess and report the uncertainty of measurement
according to ISO 16063-1:1998, Annex A, to document their uncertainty expressed as expanded uncertainties
for a coverage factor of 2 or a coverage probability of 95 %. It is the responsibility of the laboratory or end user
to make sure that the reported values of expanded uncertainty are credible.
4 Determination of transverse sensitivity using a single-axis vibration generator
4.1 Apparatus
The single-axis test system of transverse sensitivity specified in this clause consists of a single-axis vibration
exciter that is equipped with a specially designed fixture that enables the transducer under test to be mounted
such that its geometric axis of sensitivity is perpendicular to the direction of motion of the vibration exciter
table (where the direction of the motion of the vibration exciter table shown in Figure 1 is defined as the
Z-direction). It shall be possible to mount the test transducer at different angles about its sensitive axis,
preferably for continuous rotation over at least 180°. An example (Reference [5]) of an octahedral fixture is
shown in Figure 1.
Another example is the use of an electro-dynamic long-stroke vibration exciter operated in combination with a
turntable driven by a stepper motor as specified in Clause 5. The amplitude of the transverse acceleration of
the fixture due to transverse motion inherent in the vibration exciter shall be less than 1 % of the acceleration
amplitude in the Z-direction at each of the test frequencies. For cases in which the measured transverse
sensitivity is less than 2 % of the sensitivity measured on the geometric axis, the transverse motion of the
vibration exciter shall meet even higher requirements (e.g. 0,2 % at the test frequencies). To ensure that the
transverse motion of the vibration exciter is sufficiently small, measurements of the transverse motion of the
total setup (vibration exciter with fixture) with a load close in shape and weight to the transducer being tested
should be performed beforehand or the transverse motion could be monitored during the measurement of the
transverse sensitivity. For the measurement of the input and output signal of the transducer to be tested, see
Clause 8.
The frequency range of the transverse test system is generally 1 Hz to 5 kHz, depending on the working range
of the vibration exciter, and on the mass of the fixtures and of the transducer tested. Acceleration amplitudes

2 2
from 1 m/s to 200 m/s can be generated.
4.2 Method
4.2.1 Test procedure
Vibrate the transducer at the reference amplitude and frequency on the geometric axis of sensitivity to
determine its sensitivity, S (briefly referred to as S). Determine the values of transverse sensitivity as a
N
function of frequency, S , by vibrating perpendicularly to the sensitive axis of the transducer at different angles
T
about its sensitive axis.
The directions and magnitudes of the maximum and minimum transverse sensitivity shall be reported at a
designated test frequency or as a function of frequency.
2 © ISO 2009 – All rights reserved

Key
1 screw unit for re-mounting the octahedron in different positions (angle shifts of 45°)
2 transducer to be tested
3 octahedron
4 reference accelerometer
5 vibration exciter table
Figure 1 — Example of a fixture for mounting the test transducer with its sensitive axis perpendicular
to the direction of the vibration generated by the vibration exciter
4.2.2 Expression of results
Calculate the transverse sensitivity, S , using Equation (1):
T
uˆ
out
S = (1)
T
aˆ
T
where
uˆ is the amplitude of the output signal of the transducer vibrating perpendicularly to its sensitive
out
axis;
aˆ is the amplitude of the acceleration in the test direction.
T
*
Calculate the relative transverse sensitivity, S , expressed as a percentage, using Equation (2):
T
S
*
T
S=×100 % (2)
T
S
where S is the sensitivity of the transducer on the geometric axis of sensitivity.
5 Determination of the transverse sensitivity using a vibration generator with
turntable
5.1 Apparatus
5.1.1 General. The single-axis test system of transverse sensitivity specified in this clause consists of a
single-axis vibration exciter and a rotating table.
NOTE An apparatus similar to Figure 2 is used by several manufacturers of accelerometers in order to comply with
[6]
criteria contained in ISA-RP 37.2 . For details of the apparatus specified as an example in the following, see
Reference [7].
w
a(t)
Key
1 rotating disk
2 drive rod
3 turntable controlled by a stepper motor
4 slide or air bearing
5 transducer to be tested
a(t) acceleration
ω angular frequency (“speed”)
Figure 2 — Example of a mechanical vibration exciter with turntable
used for the measurement of the transverse sensitivity
The crank is driven at a constant speed, ω , by an electric motor via a toothed belt. The slider, in turn, drives a
carriage, the motion of which is constrained by two bars with bronze sockets. On the carriage, there is a
turntable whose motion is controlled by a stepper motor. The carriage is made to oscillate at approximately
4 © ISO 2009 – All rights reserved

12 Hz with a 25,4 mm peak-to-peak amplitude, which corresponds to a root mean square (r.m.s.) acceleration
value of 51 m/s .
The accelerometer to be tested is held in place on the turntable of the carriage through, for instance, a
¼-28 UNF hole drilled in the centre of the turntable. Normally the accelerometer is placed such that the
geometric axis is perpendicular to the direction of acceleration. However, by using specially designed
adaptors, the geometric axis of the accelerometer can be aligned with the direction of motion of the carriage.
Then, the sensitivity on the geometric axis of the accelerometer can be determined at the same excitation
frequency as its transverse sensitivity. The accelerometer then can be mounted with its geometric axis
perpendicular to the direction of motion of the carriage to determine transverse sensitivity as a function of the
orientation angle, as illustrated in Figure 3. The time to complete one revolution can be between 30 s and
120 s, depending on the resolution, especially for the direction of least cross-axis sensitivity.
12 3
4 7
89 10 11
12 13
Key
1 power supply/coupler (or) charge amplifier 8 angular position controller for items 4 and 7
2 filter 9 stepper motor
3 digital voltmeter (DVM) 10 controller
4 angular position detector part A 11 computer
5 carriage 12 driver
6 transducer under test mounted on turntable 13 a.c. motor
7 angular position detector part B 14 turntable control panel
Figure 3 — Example of block diagram of complete signal conditioning and data acquisition system
It is recommended that an accelerometer be permanently or periodically placed in the direction of the slider
motion to monitor the condition of the exciter. By double integration, the value of amplitude of displacement
can be computed from the acceleration experienced in the excitation axis and hence a comparison drawn
between the observed value and the expected value (25,4 mm).
The transverse test system is generally operated at a fixed frequency between 5 Hz and 15 Hz and a fixed
displacement amplitude (25,4 mm peak-to-peak amplitude is widely preferred, see Note).
5.1.2 Vibration exciter assembly. In the example introduced in 5.1.1, the vibration exciter consists
essentially of a three-phase synchronous a.c. motor and a mechanical excitation unit. The excitation unit itself
is composed of a crank-slider mechanism driving the carriage with the turntable, controlled by a stepper motor,
on to which the transducer under test is mounted. With a power line frequency of 50 Hz, the synchronous
speed, n, is 1 500 r/min for the 4-pole motor in use.
NOTE The use of a 3-phase, 4-pole synchronous motor is not mandatory. To simplify the setup, a special series-
wound single-phase motor can be used working in a synchronous way with the power line frequency.
5.1.3 Signal conditioning and data acquisition system. In general, the output of the unit under test
requires signal conditioning, including filtering and amplification. The signal conditioning unit may be
comprised of a power supply, voltage or charge amplifier, and a 24 dB/octave narrow analogue band-pass
filter which can be a combination of a high-pass and a low-pass filter. The filtered signal is connected to the
input of the DVM which is in turn connected to a computer via a suitable digital interface. Figure 3 shows a
block diagram of an example of a complete signal conditioning and data acquisition system.
5.2 Method
Mount the transducer in a test arrangement such that the known vibratory motion in a plane perpendicular to
the sensiti
...