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JJF 1943-2021: Calibration Specification for Shock Measuring Instruments
JJF 1943-2021
JJF
METEROLIGICAL TECHNICAL SPECIFICATION
OF THE PEOPLE’S REPUBLIC OF CHINA
Calibration specification for shock measuring instruments
ISSUED ON: DECEMBER 08, 2021
IMPLEMENTED ON: JUNE 08, 2022
Issued by: State Administration for Market Regulation
Table of Contents
Introduction ... 4
1 Scope ... 5
2 Normative references ... 5
3 Overview ... 5
4 Metrological characteristics ... 6
4.1 Shock acceleration peak sensitivity of the shock kit ... 6
4.2 Annual stability of acceleration peak sensitivity of the shock acceleration standard set
... 7
4.3 Shock acceleration peak indication error ... 7
4.4 Repeatability of shock acceleration peak measurement ... 7
4.5 Pulse duration indication error ... 8
4.6 Velocity change indication error (if applicable) ... 8
4.7 Shock acceleration amplitude linearity ... 8
4.8 Channel consistency (if applicable) ... 9
4.9 Dynamic range (if applicable) ... 9
5 Calibration conditions ... 9
5.1 Environmental conditions ... 9
5.2 Standard devices for calibration ... 10
6 Calibration items and calibration methods ... 11
6.1 Calibration of shock acceleration peak sensitivity ... 11
6.2 Calibration of shock acceleration peak indication error ... 11
6.3 Calibration of shock acceleration peak measurement repeatability ... 11
6.4 Calibration of pulse duration indication error ... 12
6.5 Calibration of velocity change indication error ... 13
6.6 Calibration of acceleration amplitude linearity ... 13
6.7 Calibration of channel consistency ... 14
6.8 Calibration of dynamic range ... 14
7 Expression of calibration results ... 15
8 Recalibration time interval ... 16
Appendix A Example of measurement uncertainty assessment for absolute calibration
of shock acceleration peak sensitivity ... 17
Appendix B Example of measurement uncertainty evaluation of shock acceleration
peak sensitivity calibrated by comparison method ... 20
Appendix C Reference format of the inner page of the calibration certificate ... 23
Calibration specification for shock measuring instruments
1 Scope
This Specification is applicable to the shock measuring instruments that characterize
the shock performance using various types of shock acceleration time history with
shock acceleration peak range of (50 ~ 2.0 × 106) m/s2 and pulse duration range of
(0.015 ~ 10) ms, including standard shock acceleration measuring instruments and
working shock acceleration measuring instruments with/without adaptive amplifier and
display part, as well as the calibration of shock acceleration laser measuring instruments.
Note: Pulse duration greater than 10 ms can refer to this Specification.
2 Normative references
This Specification refers to the following documents:
JJF 1156 Terminology and definitions for measurement of vibration, shock and
rotating velocity
JJG 2072-2016 Measuring instruments for shock acceleration
GB/T 2298-2010 Mechanical vibration, shock and condition monitoring -
Vocabulary (ISO 2041:2009)
GB/T 20485.1-2008 Methods for the calibration of vibration and shock transducers
- Part 1: Basic concepts (ISO 16063-1:1998)
GB/T 20485.13-2007 Methods for the calibration of vibration and shock transducers
- Part 13: Primary shock calibration by laser interferometry (ISO 16063-13:2001)
GB/T 20485.22-2008 Methods for the calibration of vibration and shock transducers
- Part 22: Shock calibration by comparison to a reference transducer (ISO 16063-
22:2005)
For dated references, only the dated version applies to this specification; for undated
references, the latest version (including all amendments) applies to this specification.
3 Overview
The shock meter is an instrument used to measure the time history of shock acceleration,
mainly characterized by its peak value and pulse duration. It usually consists of an
5.2 Standard devices for calibration
5.2.1 Shock acceleration standard/calibration device
The standard shock acceleration meter (or shock acceleration standard kit) or shock
acceleration laser meter used as the main standard of the shock acceleration
standard/calibration device shall be calibrated with the absolute shock metrology
reference or metrology standard device. Other shock meters can be calibrated with the
absolute or comparative shock acceleration standard device.
5.2.2 Shock waveform recorder (optional)
5.2.2.1 Digital storage oscilloscope
The oscilloscope shall have a bit number of not less than 12 bits, a sampling rate of not
less than 100 MHz, a bandwidth of not less than 1 MHz, an integral error of less than
1%.
5.2.2.2 Data acquisition system
The amplitude resolution, sampling rate, storage space of the data acquisition system
or waveform recorder shall meet the needs of shock acceleration measurement. Usually,
the amplitude resolution of the acquisition card is not less than 10 bits; the sampling
rate is at least greater than 10/T, where T is the pulse duration of the shock waveform.
For a measurement system that uses charge amplifier integration to obtain a shock
velocity waveform, its single integral error shall be less than 3%; for a system that uses
software integration to obtain an shock velocity waveform, its integral error shall be
less than 2%.
5.2.2.3 Dynamic signal analyzer
The frequency indication error of the dynamic signal analyzer is better than 0.01%; the
spectrum amplitude indication error is better than 2%; the amplitude consistency
between any two channels of the instrument is better than 0.1 dB; the phase consistency
is better than 1°.
5.2.3 Filter
To avoid signal aliasing and suppress noise, the filter used shall have appropriate
amplitude-frequency and phase-frequency responses; the filter effect of the selected
cutoff frequency shall meet the measurement uncertainty requirements.
5.2.4 Standard capacitor (optional)
The standard capacitor of 1000 pF or 10000 pF has an accuracy level of 0.1.
5.2.5 Sine signal generator (optional)
The distortion of the single-frequency sine signal generated by the sine signal generator
is less than 0.1%; the frequency stability is better than 0.1%; the amplitude stability is
better than 1% (8 h).
6 Calibration items and calibration methods
6.1 Calibration of shock acceleration peak sensitivity
Use the specified torque value to rigidly fix the accelerometer of the shock measuring
instrument to be calibrated on the shock standard/calibration device; the sensitivity of
the matching adaptive amplifier is set at 1 pC/Unit (or mV/Unit). It is recommended to
select no less than 7 points (including the minimum and maximum acceleration peaks)
within the range of the calibrated shock measuring instrument for measurement, to
obtain a set of shock acceleration sensitivities Si under the conditions of a standard
shock acceleration peak ai, i = 1, 2, …, N, N is the number of shock calibration points.
The expanded uncertainty of the shock acceleration peak sensitivity Si is evaluated in
accordance with Appendix A or Appendix B.
6.2 Calibration of shock acceleration peak indication error
It is recommended to select no less than 7 calibration points (including the minimum
and maximum acceleration peaks) within the operating range of the shock meter; the
shock meter is set to the corresponding shock acceleration sensitivity gear. Measure
once at each of the selected calibration points to obtain two measurement columns {a0,
i} and {a1, i} of the standard shock acceleration peak and the shock meter indication
respectively. At the same time, record the corresponding pulse duration measurement
columns {T0, i} and {T1, i}. The pulse duration is the time interval between the shock
acceleration rising to 10% of the peak value and falling to this value. If the shock meter
to be calibrated has an integration function, it is also necessary to record the velocity
change {v0, i} calculated by the shock acceleration standard/calibration device and the
velocity change {v1, i} calculated by the shock meter.
Calculate the acceleration indication error δa, i of each point according to formula (1):
6.3 Calibration of shock acceleration peak measurement repeatability
Under the condition that the standard/calibration device can produce repeated shock
power; when the accelerometer is stationary, measure and calculate the variance of the
noise as σ2; the maximum measurable sinusoidal voltage peak value of this position is
U (given in the manual), then the dynamic range D (in dB) is:
7 Expression of calibration results
The calibration certificate shall include at least the following information:
a) Title: "Calibration certificate";
b) Name and address of the laboratory;
c) Location of calibration (if different from the address of the laboratory);
d) Unique identification of the certificate (such as number), page number, total
number of pages;
e) Name and address of the customer;
f) Description and clear identification of the object to be calibrated;
g) Date of calibration and, if relevant to the validity and application of the calibration
results, the date of acceptance of the object to be calibrated;
h) Name and code of the technical specification on which the calibration is based;
i) Traceability and validity of the measurement standard used for this calibration;
j) Description of the calibration environment;
k) Description of the calibration results and their measurement uncertainty;
l) Description of deviations from the calibration specification;
m) Signatures of the calibrator, verifier, approver;
n) Statement that the calibration results are only valid for the object to be calibrated;
o) Date of issuance of the calibration certificate and a recommendation on the time
interval between recalibrations;
p) Statement that the certificate may not be partially reproduced without the written
approval of the calibration laboratory.