ISO 23670:2021

INTERNATIONAL ISO
STANDARD 23670
First edition
2021-09
Space systems — Vibration testing
Systèmes spatiaux — Essais de vibration
Reference number
©
ISO 2021
© ISO 2021
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Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 General . 2
6 Test technical requirements . 3
6.1 Test specification . 3
6.2 Tolerances . 3
6.3 Test control . . 3
6.3.1 Control strategy . 3
6.3.2 Control point . 4
6.4 Specimen configuration requirements . 5
6.5 Response measurement point . 5
6.6 Test success criteria . 5
7 Test system . 5
7.1 Test facility requirements . 5
7.2 Equipment requirements . 6
7.2.1 Shaker . 6
7.2.2 Fixture . 7
7.2.3 Force measurement device (FMD) . 7
7.2.4 Vibration control system . 9
7.2.5 Measurement system .10
8 Test procedure .11
8.1 Test preparation .11
8.1.1 Preparation of the test documents .11
8.1.2 Check of test equipment and test specimen .11
8.1.3 Safety check .12
8.2 Test implementation .12
8.2.1 General.12
8.2.2 Before test .12
8.2.3 During test .12
8.2.4 After test . .13
9 Test interruption and handling .13
9.1 Test interruption .13
9.2 Interruption handling .13
10 Test data and result evaluation .13
10.1 Test data .13
10.2 Result evaluation .14
11 Test reports .14
Annex A (Informative) A method for random vibration and acoustic test tailoring.15
Annex B (Informative) An example of notching principles and calculation method for
notching control .18
Annex C (informative) Force limit determination .20
Bibliography .28
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
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicle,
Subcommittee SC 14, Space systems and operations.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved

Introduction
Vibration testing is one of the most important test items of space systems. The primary goals of
vibration testing are to verify the design and to detect manufacturing issues of spacecraft, subsystems
and units that could result in in-flight failures. In design, material selection, manufacture, assembly and
integration phase, the test aims on exposing defects and non-conformances existing and eliminating
potential quality problems. With regard to the launch phase, it also serves to prevent structural failure
of a space system, loosening of fasteners and connectors, failure of electronic components, leakage of
sealing elements or malfunction of mechanical system.
During vibration testing, over-testing can result in unnecessary destruction of the test specimen. In
the 1990s, at the Jet Propulsion Laboratory, Mr. Terry Scharton elaborated the methodology of force
notching for qualification of satellites and spacecraft to mitigate unnecessary over-testing. Since then,
several attempts have been made to establish this methodology for a broader range of application. This
document includes the methodology of force-based testing.
INTERNATIONAL STANDARD ISO 23670:2021(E)
Space systems — Vibration testing
IMPORTANT — The electronic file of this document contains colours which are considered to be
useful for the correct understanding of the document. Users should therefore consider printing
this document using a colour printer.
1 Scope
This document provides guidance and requirements for test providers and interested parties to
implement vibration testing.
This document specifies methods, including the force limiting approach, to mitigate unnecessary over-
testing of spacecraft, subsystems and units for space application.
The technical requirements in this document can be tailored to meet the actual test objectives.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitute requirements 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 15864:2021, Space systems — General test methods for space craft, subsystems and units
ISO 19924:2017, Space systems — Acoustic testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
notching
reduction of the input level or spectrum in a vibration testing to limit structural responses at resonant
frequencies according to qualification or acceptance loads to avoid over-testing.
3.2
response limited vibration testing
reduction of input acceleration in a vibration testing to maintain the measured response at or below a
specified value
3.3
force limited vibration testing
reduction of reaction force in a vibration testing to specified values, which are usually the interface
forces predicted for flight, plus a desired margin.
3.4
statistical DOF
number of independent variables in a statistical estimate of a probability
Note 1 to entry: The number of degrees of freedom determines the statistical accuracy of an estimate.
[SOURCE: ISO 2041:2018, 3.5.16, modified — The term has been changed from "statistical degrees of
freedom" to "statistical DOF".]
4 Abbreviated terms
For the purposes of this document, the abbreviated terms described in Table 1 apply.
Table 1 — Abbreviated terms
DOF degree of freedom
FEA finite element analysis
FLV force limited vibration
FLVT force limited vibration test
FMD force measurement device
FRF frequency response function
POGO propulsion generated oscillations
PSD power spectral density
RMS root mean square
TDFS two-degree of freedom system
5 General
Vibration testing is distinguished between sinusoidal vibration testing and random vibration testing.
Sinusoidal vibration testing is intended to simulate the vibration environment produce by unstable
combustion, by coupling of structural resonant frequencies (POGO), by imbalances in rotating
equipment. Sinusoidal vibration testing is also to simulate ground transportation and handling, due to
resonant responses of tires and suspension systems of the transporters.
Random vibrations are generated by the launcher engines and by acoustic and aerodynamic excitation
of the launch vehicle and spacecraft fairing. During flight or ground transportation and handling, broad
band vibration environment is imposed on the spacecraft. ISO 15864 recommends either vibration or
acoustic testing, whichever is more appropriate, with the other one left optional. Generally, if acoustic
testing is performed, random vibration may be skipped. For a small compact spacecraft, acoustic testing
does not provide adequate environmental simulation, and random vibration may replace the acoustic
test. To take this decision it is important to consider:
— vibration testing do not reach high frequency contents;
— whether the structure is sensitive to acoustic loads;
— whether the structure is sensitive to acoustic loads where the units are mounted.
Information for random vibration and acoustic test tailoring is provided in Annex A.
Conventional acceleration control during vibration testing may lead to the so-called over-testing
problem due to the difference of the interface impedance of the mounting structure and the shaker.
In order to overcome this problem, the force limited vibration (FLV) testing technique was developed.
In the FLV testing, in addition to the acceleration specification, the specification of the reaction force
between fixture and test specimen shall be defined. Using the FLV technique, both the acceleration
and force at the interface of test specimen and fixture are limited so that the vibration environment
characterizes the real situation more precisely.
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6 Test technical requirements
6.1 Test specification
The test specification shall meet the requirements of the respective launch vehicle user manual.
The test specification generally includes testing level, frequency range, test direction and test duration.
The duration of sinusoidal vibration testing is determined by the sweep rate and frequency range. The
duration of random vibration testing is expressed in seconds or minutes. The test directions usually
correspond with the three orthogonal axes, one of which is in accordance with the launch direction.
If FLVT will be applied, the test specifications shall be extended with the FLVT requirements.
When needed to re-check workmanship by dynamic mechanical environmental test for flight units that
have undergone rework and that required random vibration testing at acceptance test, the minimum
retesting shall be random vibration testing at workmanship screening level to be agreed with the
customer. However, if the most effective single axis of workmanship screening re-test for all the
reworked areas is determined, re-test excitation can be based just on that axis.
6.2 Tolerances
The tolerances shall be determined based on the design standard. If not specified otherwise, the
following test level tolerances can be used.
a) Sinusoidal vibration
Frequency: −2 % to +2 % (or −1 Hz to +1 Hz, whichever is greater)
Acceleration amplitude: −10 % to +10 %
b) Random vibration
Acceleration spectral density (frequency resolution better than 10 Hz)
10 Hz to 100 Hz (analysis bandwidth 10 Hz or narrower): −3 dB to +3 dB
100 Hz to 1 000 Hz (analysis bandwidth is 10 % or narrower of the central frequency): −3 dB to +3 dB
1 000 Hz to 2 000 Hz (analysis bandwidth 100 Hz or narrower): −3 dB to +3 dB
Statistical DOF: not less than 100
Overall grms.: −10 % to +10 %
Test duration: −0 % to +10 %
6.3 Test control
6.3.1 Control strategy
6.3.1.1 General
The control strategy shall provide the required vibration at the required locations in or on the test
specimen. This depends on the kind of vibration to be generated and on the test specimen/shaker
interaction. Generally, a single strategy is appropriate (e.g. only acceleration input control strategy
is used). There are cases where multiple strategies are used simultaneously (e.g. acceleration input
control strategy and force limited vibration testing strategy are used simultaneously).
6.3.1.2 Acceleration input control
Acceleration input control is the basic method of vibration testing. The control accelerometers shall
be mounted on the fixture at the test specimen mounting points. Shaker motion shall be controlled
with feedback from the control accelerometer(s) to provide defined vibration levels at the fixture/ test
specimen interface.
6.3.1.3 Notching
Notching is a general accepted practice in full-level vibration testing to avoid over-testing.
Implementation of notching shall be subject to customer approval and relevant to Launcher authority
approval. Refer to Annex B for an example of the notching calculate method. The following requirements
apply.
a) The force on the main structure shall not be higher than the design value of quasi-static load plus a
desired margin.
b) The vibration level shall not be less than the level of coupling analysis result for the interface
between spacecraft and launcher, unless agreed by the launcher authority.
c) The response of key equipment fixed position shall not be higher than the equipment vibration
testing level.
6.3.1.4 Force limited vibration testing
For force limited vibration testing, the vibration level is defined by acceleration. In addition, the
reaction force between fixture and test specimen shall be measured and limited. Dynamic force gauges
are mounted between the fixture and the test specimen. If the force achieves the limited value, the
exciter motion shall be controlled with feedback from the force gages.
Force limiting is most useful for test specimens that exhibit distinct, lightly damped resonances on the
shaker. The amount of relief available from force limiting is greatest when the structural impedance
of the test specimen is equal to, or greater than that of the mounting structure in the actual mounting
situation.
The force limit value shall be slightly larger than the real reaction force of the interface during launch,
plus the desired margin. Force limits value can be determined in several ways including simple and
complex TDFS Method, semi-empirical method, FEA method, quasi-static-load method, apparent
masses envelope method and design/flight loads method. A non-exhaustive list of force limit method is
specified in Annex C.
6.3.1.5 Response limited vibration testing
For response limited vibration testing, the vibration level is defined by acceleration. In addition,
vibration response limits at specific points on the test specimen shall be defined. Monitoring
accelerometers shall be located at these points. The test specimen shall be excited using control point
accelerometer signals to control the exciters. The control inputs shall be automatically modified as
needed to limit responses at the monitoring accelerometers to the predefined limits. This strategy is
used to avoid damage to the specific equipment or lower level assembly.
6.3.2 Control point
The control accelerometer(s) shall be mounted on the test fixture near the specimen attachment points.
For multiple-point control, an even distribution should be adopted. In case specific requirements
exist, the positions of the control points shall be determined accordingly. If more than one control
accelerometer is used, the test levels may be controlled by a control scheme either based on the
average response or on the response extremes. The control scheme shall be consistent with the test
requirement.
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6.4 Specimen configuration requirements
The specimen configuration shall be as described in ISO 15864:2021, 7.13.3 and 7.14.3.
6.5 Response measurement point
The test requirements shall specify the number, installation position and orientation, type and
measurement range of test sensors, as well as the processing modes and requirements for data
measurement. See more detailed requirements in 7.2.5.
6.6 Test success criteria
It is presupposed that an accomplished test is formally compliant with the contract requirements.
For the test provider, if not specified otherwise, the following requirements shall apply.
— All vibration testing shall be applied at the right test level.
— The acquisition of test specimen vibration response data shall be complete and valid.
For the specimen provider, if not specified otherwise, the following requirements shall apply.
— The intended test purposes shall be achieved.
— There shall be no visual damage to the test specimen.
— The characteristic response curve (which includes the resonance frequencies and the amplification
ratio) shall be the same before and after each full level vibration testing (see 8.2.3 a)) under
consideration of the specified tolerance bands.
— The test specimen performance after the test shall be specified by the customer.
7 Test system
7.1 Test facility requirements
A vibration testing facility includes a vibration excitation system, a vibration control system, a
measuring system and auxiliary equipment. An example of a vibration testing facility is shown in
Figure 1.
For FLVT, dynamic force gauges are mounted between the shaker/fixture and the test specimen. The
force at the interface is measured by the force gauges and is fed back to the control system to implement
response limiting.
Key
1 accelerance signal conditioner 7 shaker
2 test specimen 8 data storage and processing system
3 force signal conditioner 9 data acquisition system
4 vibration controller 10 measurement system
5 power amplifier 11 accelerometer
6 force measurement device (for FLV) 12 force gauge
Figure 1 — Illustration of a force limited testing system
The test facility, including all auxiliary equipment,
— shall provide the specified vibration environments,
— shall implement the required control strategies, and
— shall meet the specified tolerances.
Measurement transducers, data recording and data reduction equipment capable of measuring,
recording, analysing, and displaying data shall be sufficient to document the test and to acquire any
additional data required.
The facility shall be maintained in regular intervals and shall be checked before test campaign.
7.2 Equipment requirements
7.2.1 Shaker
The requirements of the shaker are as follows.
a) The shaker test facility shall fulfil the requirements of the test concerning power, dimension,
applicable forces and moments with a margin. The test requirements shall not be limited by the
shaker performance.
b) The static load capacity shall be greater than the sum of mass of the test specimen, moving part of
the shaker and the fixture. Flexible supports are necessary if this requirement cannot be met. The
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natural frequency of this supporting system shall be less than the lowest test frequency, and the
allowed displacement shall be no less than the required displacement.
c) The maximum displacement of shaker shall be greater than that required by the test conditions.
d) The shaker frequency range shall allow reaching the upper and lower limit frequencies specified in
the test conditions.
7.2.2 Fixture
The requirements for the test fixture are as follows.
a) The fixture stiffness-and-mass ratio shall be as large as possible.
b) The fixture shall mate with the test specimen in the same way as the flight interface does, so that
the interface load distribution is similar to that in flight.
c) The acceleration response of the interface between fixture and test specimen shall be uniform in
the test frequency range.
d) The first natural frequency of the fixture shall be higher than the higher frequency of the vibration
testing. When this requirement cannot be met, the first natural frequency of the fixture is a number
of times “N” of the first natural frequency of the test specimen. The number of times “N” shall be
greater than 3 and agreed with the customer. Any additional notching or input level reduction
cause by the fixture shall comply with requirements of 6.3.
e) S force measurement device is used as test fixture in FLVT, requirements for a force measurement
device are specified in 7.2.3.
f) The vibration fixture configuration, and its interfaces to the test specimen / vibration source /
other ground support equipment, shall be defined, inspected, fit checked and proof tested well
before the vibration testing is carried out.
7.2.3 Force measurement device (FMD)
7.2.3.1 General
In case a force limited vibration testing is performed, a force measurement device (FMD) shall be
utilized instead of the fixture specified in 7.2.2 for both the support of the test specimen and the
measurement of the force at the interface between the test specimen and the shaker.
7.2.3.2 Force measurement device design
A force measurement device consists of three parts: an upper-adapter, tri-axial force gauges and a
lower-adapter. A sketch of a typical FMD is illustrated in Figure 2.
Key
1 test specimen 4 lower-adapter
2 upper-adapter 5 shaker
3 tri-axial force gauges
Figure 2 — An illustration of a typical FMD
The mass of the upper-adapter should be as small as possible, normally less than 10 % of the test
specimen. The resonance frequency of an FMD shall be no less than the upper limit of the test frequency.
For tri-axial force gauges, the following requirements and recommendations apply.
a) Piezo-electric force gauges should be used. The dimensions and dynamics shall be chosen according
to the structure of the test specimen and the test level.
b) Multiple force gauges should be normally evenly distributed to obtain a better test result.
c) The force gauges shall be pre-loaded (normally by the manufacturer) before used in force limited
vibration testing.
d) The influence of dynamic behaviour caused by FMD shall be assessed to comply with requirements
of 6.3.
7.2.3.3 Force measurement device verification
7.2.3.3.1 General
Multiple tri-axial force gauges are often used to implement force limited vibration testing. A typical
force measurement device is illustrated in Figure 3. The resultant force and resultant moment depend
on the distribution of force gauges. A typical FMD is described and corresponding resultant force and
resultant moments are formulated in Annex C.
8 © ISO 2021 – All rights reserved

Key
1 test specimen 3 tri-axial force gauges
2 upper-adapter 4 lower-adapter
C centre of gravity of the test specimen X, Y, Z directions of the reference system of the test item
h height of the upper-adapter H distance from the centre of gravity of the test
specimen to the top of the upper-adapter
Figure 3 — Illustration of a typical force measurement device
7.2.3.3.2 FMD verification of vertical direction
Without loss of generality, assume that a test specimen vibrates along the Z axis during a test in the
vertical direction. The forces measured by each force gauge in each direction as well as the resultant
force and resultant moment shall be verified by a rigid body mass properties of the test item including
upper adapter. The verification test frequency shall be lower than the first resonant frequency so that
the dynamic amplification is negligible. Normally the beginning frequency of the test is picked for the
verification.
Ideally, the verification criterion is that all the resultant forces and moments shall be equal to zero
except in the Z direction. The measured forces in the Z direction for all force gauges should be equal to
or rather similar to each other.
7.2.3.3.3 FMD verification of horizontal direction
Without loss of generality, assume that a test specimen vibrates along the Y axis during a test in the
horizontal direction. The verification test frequency shall be lower than the first resonant frequency so
that the dynamic amplification is negligible. Normally the beginning frequency of the test is picked for
the verification.
The verification criterion of the horizontal direction is as follows: Ideally, all the resultant forces and
moments shall be equal to zero except the resultant force in the Y direction and the bending moment
in the X direction. The transverse forces for all force gauges should be similar to each other. The phase
is the same for the Z direction forces for the transducers with –Y coordinate and are opposite of those
transducers with +Y coordinate.
7.2.4 Vibration control system
A vibration control system typically includes: vibration controller, acceleration sensor, signal
conditioning system. The acceleration sensor and the signal conditioner shall meet the relevant
requirements of 7.2.5.2 and 7.2.5.4. The vibration control system shall meet the following requirements.
a) The vibration control system shall at least have the functions of sinusoidal vibration and random
vibration testing control.
b) The vibration controller shall have the functions of multi-point averaging, maximum or minimum
control.
c) The vibration controller shall have a response limit function.
d) For force limit vibration testing, dual controlled vibration testing shall be used. This means
controlling the test by acceleration control channels and additional notching channels for the
defined force limits.
1) The vibration controller shall be capable of “extremal control,” (also called maximum or peak
control). In extremal control, the largest of a set of signals is limited to a single reference
spectrum.
2) The vibration controller shall accommodate different reference spectra for limiting individual
response (and force) measurement channels.
e) The vibration controller shall have an automatic abort function to avoid overloads on a test
specimen due to control disturbance.
7.2.5 Measurement system
7.2.5.1 General
Typically, the measurement system is composed of sensors (e.g. accelerometer, strain gauge), signal
conditioners, a data acquisition system, data storage and a processing system.
7.2.5.2 Sensor requirements
7.2.5.2.1 Accelerometers
a) The sensitivity and range of the accelerometers shall consider the response size of the measured
component and background noise.
b) Accelerometers in different weight shall be chosen according to the local stiffness and weight of the
measured part to reduce the influence of additional mass.
c) The lateral sensitivity of the accelerometer shall not be greater than 5 % of the sensitivity in the
spindle direction.
d) The deviations from amplitude linearity of the accelerometer shall not be greater than 1 % in the
experimental range.
7.2.5.2.2 Strain gauge
To measure the strain, the gauge’s form, size, range and accuracy shall be selected according to test
purpose. The cables used shall be low noise cables.
7.2.5.3 Installation of sensors
The installation and routing of the sensor shall neither impose additional restrictions on the test
specimen, nor modify the response characteristics of the product.
7.2.5.4 Signal conditioners
a) The filter of the signal conditioners shall have linear phase-shifting characteristics. The error in
the experimental frequency range shall be within ±1 dB;
b) The amplitude linearity shall not be greater than 1 %.
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c) The signal conditioners shall have the function of signal calculation for force signal regulators,
including calculation function of resultant force, splitting moment and resultant moment, and gain
attenuation setting of output signals.
7.2.5.5 Data acquisition and processing system
a) The data acquisition system shall be able to acquire signals of accelerometers, strain gauges and
other required sensors.
b) The data acquisition system shall have sinusoidal vibration and random vibration data acquisition
modules, with functions of real-time data acquisition, recording, processing and analysis.
c) The data acquisition system shall have enough measurement channels to meet the requirements of
the customer.
d) Measurement uncertainties shall meet the requirements of the customer.
8 Test procedure
8.1 Test preparation
8.1.1 Preparation of the test documents
The test documents shall be prepared according to ISO 15864:2021, 4.9. The test documents shall be
reviewed by the customer. Before starting a test, the test plan shall be reviewed to determine test
specimen configuration(s), levels, durations, vibration exciter control strategy, item operational
requirements, instrumentation requirements, facility capability and fixture.
a) Appropriate vibration exciters and fixtures shall be selected.
b) An appropriate data acquisition system composition (e.g. instrumentation, cables, signal
conditioning, recording and analysis equipment) shall be selected.
c) The vibration equipment shall be operated without the test specimen installed to confirm proper
operation.
d) The data acquisition system functions shall be ensured as required.
e) If FLVT is applied, the structure analysis results (resonance frequencies, modal effective mass, etc),
interface conditions (materials, masses, parts, etc.), quasi-static loads, flight limit loads and design
loads shall be specified.
8.1.2 Check of test equipment and test specimen
Check shall be performed before test conduction. If not specified otherwise, the following requirements
apply.
a) The test setup shall be as specified in the test requirements.
b) It shall be ensured that the performance capability of the test equipment meets the test
requirements.
c) All the test equipment shall be calibrated and used in the valid period.
d) The test specimens shall be examined for physical defects.
e) The test specimen shall be configured for test, in its operating configuration if required, as specified
in the test plan.
f) The test specimen/fixture/exciter combination shall be examined for compliance with test
specimen and test plan requirements.
g) An operational checkout shall be conducted in accordance with the test plan and the results shall
be conducted for comparison with data taken during or after the test.
8.1.3 Safety check
The safety check shall be in accordance with ISO 19924:2017, 9.2.1.3.
8.2 Test implementation
8.2.1 General
Vibration testing on spacecraft system level is generally conducted in each of the three orthogonal
directions. For each test, the test implementation shall consider the following sequence.
8.2.2 Before test
a) The test specimen shall be mounted to the fixture according to the required test direction. If the
static load of the vibration system cannot meet the requirements, an auxiliary flexible support may
be installed after customer approval.
b) The control transducers shall be installed on fixture as required.
c) A visual inspection and a functional test of the specimen shall be performed.
d) The parameters of the control and measurement systems shall be set, and the readiness of all
systems for the test shall be verified.
e) A pre-test shall be performed to measure the structure response and to check the control and
measurement systems.
8.2.3 During test
a) If not specified otherwise, the following test sequence shall be performed. A low-level pre -test
shall be performed. The test shall be carried out according to the test level conditions specified in
the test specification. The structural response shall be recorded and, if required, the test specimen
performance shall be monitored during the test. After completing the test, all data shall be
analysed to determine the conditions of full level vibration testing, such as notching requirement
and response limit profile.
b) A full-level vibration testing shall be performed. Structural responses shall be recorded and, if
required, the test specimen performance shall be monitored. After the test, the connecting screws
between the test specimen and the fixture shall be checked to ensure that connecting screws are
not loose.
c) A low-level vibration testing shall be performed again. After the test, both low-level testing results
shall be evaluated to evaluate the test specimen integrity by comparing its resonance frequencies
and amplification factors.
If the test plan calls for additional intermediate or full-level testing, steps a) through c) shall be repeated
as required by the test plan before proceeding.
A low-level sweep down sine test should be performed in case of suspicion of nonlinear behaviour, or
unexpected behaviour during sweep up test.
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8.2.4 After test
a) After the completion of testing in one direction, a visual inspection of the test specimen shall be
performed. Functional and electrical performance tests shall be conducted if necessary.
b) In case failures, structural degradation or other anomalies are found during the test, the test
interruption and handling requirements shall be considered.
9 Test interruption and handling
9.1 Test interruption
If either of the following situations appears, the test shall be interrupted:
a) laboratory equipment malfunctions;
b) the technical requirements cannot be met due to exceeding test tolerances;
c) test specimen operation failure.
9.2 Interruption handling
Test interruption should be handled as follows.
a) If a test is interrupted because of test equipment malfunction, the test shall only be continued after
the failure had been eliminated and it is made sure there is no effect on the specimen.
b) If a test is interrupted because the technical requirements cannot be met due to exceeding test
tolerances, after eliminating the reason the parameters shall be reset and the test shall be
performed again. In case of under-testing, test results acquired before the interruption shall be
considered invalid. In case of over-testing, it shall be ensured there was no effect on the specimen
and the test may be restarted from the interruption point (in that case, of the total duration before
and after the interruption shall be considered as test duration).
c) If a test is interrupted because of test specimen operation failure, the test shall only be continued
after the interference or failure had been eliminated.
10 Test data and result evaluation
10.1 Test data
Typically, vibration testing data includes the following items:
a) control results of the test;
b) structure response of the test specimen in the frequency domain, and, if specified in the contract
requirement, in the time domain;
c) environment data of laboratory;
d) status data of the equipment;
e) status data of the test specimen.
Test data requirements shall conform to ISO 15864:2021, 4.9.5.
10.2 Result evaluation
After test, the results shall be evaluated according to the following criteria:
a) conformance of the control results with the test requirements;
b) conformance of the measurement results with the test requirements;
c) conformance of the overall results with the test obj
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