ISO 22183:2023

INTERNATIONAL ISO
STANDARD 22183
First edition
2023-05
Plastics — Validation of force-time
curves obtained from high-speed
tensile tests
Plastiques — Validation des courbes force-temps obtenues à partir
d'essais de traction à grande vitesse
Reference number
© ISO 2023
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 4
5 Measurement of the natural oscillation spectrum of the grip and force transducer
configuration .5
5.1 Measurement of natural oscillation frequencies . 5
5.1.1 Set-up of the high-speed tensile equipment . 5
5.1.2 Set-up of the striker . 5
5.1.3 Measurement procedure . 5
5.2 Determination of the natural oscillation spectrum . 6
6 Validation . . 7
6.1 Minimum event time . 7
6.2 Maximum allowed intensity . 8
7 Test report . 9
Annex A (informative) Configuration of the high-speed testing machine .11
Annex B (informative) Example for the measurement of natural oscillation frequencies .15
Annex C (informative) Influence of a set position on the natural oscillation spectrum .18
Annex D (informative) Relation between the nominal test speed and the nominal strain .21
Bibliography .23
iii
Foreword
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iv
Introduction
The method described in this document provides criteria for the validation of measurement curves
obtained from high-speed tensile tests.
Force, time, travel and strain measurement systems of high-speed tensile equipment are usually
calibrated in static mode. Dynamic effects, occurring at such tests, need to be addressed and limits or
ranges of use for the obtained assessment parameters need to be set in order to allow the validation of
the obtained measurement curves.
This document contains a method to measure the spectrum of the natural mechanical frequencies of
the force transducer and grip arrangement, considering that these frequencies are the most important
limiting factor for the range of use of a high-speed tensile test equipment.
In addition, there are further parameters which may play a role for the dynamic quality of the
measurement curves, such as the data acquisition frequency, or oscillations generated in the machine
frame. These parameters should be carefully supervised, and measures need to be taken if such
problems occur in a significant way.
In case direct travel or strain measurement is used to generate stress-strain curves or to determine
nominal or local strain rates, further parameters, such as the synchronization between force, time and
strain channels, need to be supervised.
v
INTERNATIONAL STANDARD ISO 22183:2023(E)
Plastics — Validation of force-time curves obtained from
high-speed tensile tests
1 Scope
This document specifies procedures for validation of high-speed tensile test data. It specifies a method
to determine the spectrum of the natural oscillation frequencies of the force transducer and grip
configuration of the high-speed tensile test equipment.
The lowest significant frequency is used for the validation. This validation procedure only applies to
force measurement systems used in high-speed tensile testing machines showing a level of resonance
influence that could be critical to the obtained result. Once the relevant frequencies of the system and
the anticipated strain for the given material are known, this method allows to calculate the theoretical
maximum allowed test speed too.
2 Normative references
There are no normative references in this document.
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
unloaded region
time domain prior to the application of the load by the striker
Note 1 to entry: See Figure 1.
3.2
striking peak
first force peak generated by the striker hitting the grip
Note 1 to entry: See Figure 1.
3.3
residual oscillations region
oscillations triggered by the striker
Note 1 to entry: It represents the force on the time domain after the strike of the striker.
Note 2 to entry: See Figure 1.
Key
X time (ms)
Y force (N)
1 unloaded region
2 striking peak
3 residual oscillations region
Figure 1 — Typical force-time signal during the impact test
3.4
maximum force within the residual oscillations
F
r,max
maximum force – intended as absolute value – present in the residual oscillations, excluding the striking
peak
Note 1 to entry: It is expressed in Newtons (N).
3.5
maximum force in the unloaded state
F
u,max
maximum absolute force value in the unloaded region
Note 1 to entry: It is expressed in Newtons (N).
3.6
natural oscillation spectrum
frequency spectrum obtained as a result of a Fast Fourier Transform Analysis of the residual oscillations
region, normalized to the largest amplitude present
3.7
frequency
f
frequency of a relevant peak in the natural frequency spectrum
Note 1 to entry: It is expressed in kilohertz (kHz).
3.8
normalized intensity of the frequency
I
normalized intensity of frequency peak in the natural oscillation spectrum
3.9
lowest relevant frequency
f
low
frequency of the first relevant peak in the natural oscillation spectrum
Note 1 to entry: It is expressed in kilohertz (kHz).
3.10
event time
t
e
time from the start point of the force-time curve without unloaded region to the point of the relevant
event to be measured
Note 1 to entry: The relevant event is either the yield point, or the break point or any other defined point.
Note 2 to entry: It is expressed in milliseconds (ms).
3.11
threshold number of waves in the event
w
N,th
minimum number of waves of the relevant lowest frequency within the event time
3.12
gripping distance
L
initial length of the part of the specimen between the grips
Note 1 to entry: It is expressed in millimetres (mm).
Note 2 to entry: See Annex A.
3.13
grip displacement
ΔL
displacement of the grip pulled to tensile direction of specimens from the beginning of the test
Note 1 to entry: It is expressed in millimetres (mm).
Note 2 to entry: Most of the loading mechanics of the high-speed tensile test device have the one side pulled and
the other end fixed, as shown in Annex A.
3.14
nominal strain
ε
t
grip displacement divided by the initial gripping distance
Note 1 to entry: It is expressed as a dimensionless ratio, or as a percentage (%).
3.15
nominal test speed
v
rate of separation of the gripping jaws
Note 1 to entry: It is expressed in metres per second (m/s).
3.16
maximum force
F
max
maximum force observed in the whole force-time curve during the high-speed tensile test
Note 1 to entry: See Figure 2.
Note 2 to entry: It is expressed in Newtons (N).
3.17
maximum amplitude of oscillations
ΔF
a,max
largest peak-to-peak amplitude of oscillations, observed over a small portion of the curve during the
high-speed tensile test, ignoring single spikes of electronic noise
Note 1 to entry: See Figure 2.
Note 2 to entry: It is expressed in Newtons (N).
Key
X
time (ms )
Y force (N)
1 event time (ms)
t
e
2 maximum force (N)
F
max
3 maximum amplitude of oscillations (N)
ΔF
am, ax
Figure 2 — Typical force-time curve during tensile test at high speed
4 Principle
The principle of this document is based on the following two acceptance criteria:
1) The measurement of the natural oscillations of grip and force transducer configuration (see 6.1)
The natural oscillation frequencies of the force transducer and grip arrangement in the testing
instrument are measured after a defined impact. These frequencies are analysed by means of a Fast
Fourier Transform (FFT) and presented by their intensity over the relevant frequency range. The
highest intensity observed is used to calculate a normalized intensity. The lowest frequency of a
relevant normalized intensity will be used to establish the validation criterion.
2) The maximum allowed inte
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