Calibration Specification for Shock Accelerometers(Absolute Method)
Some standard content:
National Metrology Technical Specification of the People's Republic of China JJF1153--2006
Calibration Specification for Shock Accelerometers (Absolute Method) Issued on 2006-05-23
Implementation on 2006-0823
Issued by the General Administration of Quality Supervision, Inspection and Quarantine JJF 1153—2006
Calibration Specification for Shock Accelerometers (Absolute Method) JJF1153—2006
This specification was approved by the General Administration of Quality Supervision, Inspection and Quarantine on May 23, 2006, and came into effect on August 23, 2006.
Responsible unit: National Technical Committee on Vibration, Shock and Rotational Speed Measurement Drafting unit: The 3004th Institute of China Aviation Industry Corporation I This specification is interpreted by the National Technical Committee on Vibration, Shock and Rotational Speed Measurement Main drafters of this specification:
Li Xinliang
Zhang Dazhi
Xu Xiaomei
Participating drafters:
Li Shanming
Cao Yiqing
JJF1153—20J6
(The 304th Institute of China Aviation Industry Corporation I) (The 304th Institute of China Aviation Industry Corporation I) (The 304th Institute of China Aviation Industry Corporation I) (The 304th Institute of China Aviation Industry Corporation I) (The 304th Institute of China Aviation Industry Corporation I) 1
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3 Terminology
3.1 Impact moving body
3.2 Differential grating laser T-interference method
4 Overview
5 Metrological characteristics
5.1 Impact sensitivity of accelerometer
Amplitude linearity of accelerometer
6 Calibration conditions
Basic conditions of calibrated accelerometer
Environmental conditions
Installation of calibrated accelerometer
6.4 Impact excitation source
Data acquisition
7 Calibration items and calibration methods
Calibration items
7.2 Method 1 (Laser T-interference method)
7.3 Method 2 (Speed change method)
Expression of calibration results
Recalibration time interval
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1 Scope
JJF 1153—2006
Calibration specification for shock accelerometer (absolute method) This specification is applicable to the absolute method calibration of shock accelerometers with a range within (102~10°)m/s. 2 References
JJF1001—1998 General metrological terms and definitions JF1059—1999 Evaluation and expression of measurement uncertainty JJG233—1996 Piezoelectric accelerometer
3 Terms
3.1 Impact moving body
Anvil on which the accelerometer to be calibrated is mounted.
3.2 Differential grating laser interferometry
When a single frequency laser is projected onto a moving incident grating plane, different orders of diffracted light produce different Doppler frequency shifts. Any two orders of diffracted light are taken as measuring beams for interference, and the frequency of the differential signal is in a simple linear relationship with the grating's moving speed. The method of measuring the moving speed of an object using this scheme is called differential grating laser interferometry.
4 Overview
Shock accelerometers are widely used in shock measurement. Commonly used shock accelerometers are piezoelectric or piezoresistive. Its mathematical model can be simplified to a single-degree-of-freedom second-order system: mt\+ cr'+hr=f()
Where: m, c, - equivalent detection mass, damping, stiffness; ", - acceleration, velocity, displacement acting on the equivalent mass: f (α) - external force.
5 Metrological characteristics
5.1 Shock sensitivity of accelerometer
The definition of shock sensitivity of accelerometer is: Ss
JJF 1153—2006
Where: S - shock sensitivity of accelerometer, pC (m/s) or mVf (mis): U. Accelerometer output charge or voltage peak, pC Or mV: a,
- input acceleration peak value, m/s2,
5.2 Amplitude linearity of accelerometer
Use the least squares method to determine the linear fitting equation of the shock sensitivity of the accelerometer. For a set of calibration data (a, S), 2=1, 2, 3,, n, the following can be obtained: Sh=Sb) +K·a
Where: K
-order coefficient, K
ugSaha
-shock sensitivity intercept, S
-average value of shock acceleration peak value, a.
Sh——average value of shock sensitivity, Ss
-number of calibrations, n=7~14.
Substituting the given acceleration peak value α into formula (2), the shock sensitivity S at this acceleration can be obtained. Substituting it into the amplitude linearity formula, the amplitude linearity Y can be obtained. The amplitude linearity formula is: Sh- Ssto
6 Calibration conditions
6.1 Basic conditions of the calibrated accelerometer
6.1.1 The specification model and number should be marked on the shell of the accelerometer. 6.1.2 The surface of the accelerometer shell should not have scratches or peeling. The roughness of the mounting base surface R, <1.6μm. 6.1.3 The output wires and connecting parts of the accelerometer should be complete, intact and reliable. 6.1.4 There is an instruction manual, which generally contains the following information: (3)
a) The quality of the accelerometer, the shell material, the mounting thread size, the overall size and the structural form. Recommended mounting torque and mounting method.
b) The environmental performance indicators of the accelerometer, such as temperature response characteristics, base strain sensitivity, acoustic sensitivity, magnetic sensitivity, transient temperature sensitivity, etc.
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c) Insulation resistance and capacitance of the accelerometer, and capacitance of the supporting cable. d) Accelerometer installation resonant frequency and polarity, as well as the maximum acceleration that can be tolerated. c) Accelerometer linear range.
6.2 Environmental conditions
6.2.1 Laboratory temperature: 20℃±5℃
6.2.2 Relative humidity: should be less than 85%.
6.2.3 There should be no strong electromagnetic field, no corrosive vapor or liquid, and no strong vibration source around. 6.2.4 The equipment used for calibration should be well grounded. 6.3 Installation of the calibrated accelerometer
6.3.1 The accelerometer is installed on the impact moving body, and the installation surface should be clean and smooth with a roughness of R. <1.6μm6.3.2 Impact moving body
a) The resonance frequency of the impact moving body and the calibrated accelerometer combination should be higher than (10/T) Hz, T is the pulse duration, $.
b) Attention should be paid to controlling the rotation and lateral movement of the impact body. c) The influence of the structural resonance of the impact machine on the impact moving body should be avoided. 6.3.3 Connecting wire
The connecting wire should use low-noise shielded cable and avoid relative movement with the calibrated accelerometer as much as possible. 6.3.4 Signal Conditioner
The signal conditioner selected for calibration has a cutoff frequency range of (0.008/T~10/T) Hz6.4 Impact Excitation Source
The impact excitation sources that can generate impact acceleration semi-stop chord waveforms include impact pendulums, falling ball impact machines, air cannon impact machines, air gun impact machines, Hopkinson impact machines, and electromagnetic energy devices. The generated acceleration should be within the following range:
Acceleration peak value: (10210°) m/s2; pulse duration: (0.05~10) ms. 6.5 Data Acquisition
For the calibration method using laser interferometry, the analog bandwidth of the acquisition equipment used for photoelectric signals is IC to 100MHz or higher, the amplitude resolution should be greater than 8 bits, and it has a certain data storage capacity. The analog bandwidth of the acquisition equipment used for accelerometer-output is LC to (10*/T) Hz or higher, the amplitude resolution should be greater than 10 bits, and it has a certain data storage capacity.
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For the calibration method using the velocity change method, the analog bandwidth of the data acquisition equipment should be (0.008/T~10/T) Hz, the amplitude resolution should be greater than 10 bits, and it should have a certain data storage capacity. 7 Calibration items and calibration methods
7.1 Calibration items include the calibration of the impact sensitivity and amplitude linearity of the accelerometer. 7.2 Method 1 (Laser Interference Method)
7.2.1 Acceleration Measurement Principle
The calibrated accelerometer is installed on the impact moving body, and its sensitive direction is consistent with the moving direction of the impact moving body. When the impact moving body is subjected to impact motion, there is a definite mathematical relationship between the time function of the moving speed [t and the time function of the Doppler frequency shift of the applied laser interferometer system: U(t) = kf -Afa(r)
where: ut) - impact speed, m/s; Afa(t)
Laser Doppler frequency shift, Hz;
kg - proportionality coefficient, unit me
Differentiation of the above formula yields:
a(t) = kr d[sf(t))
Where: a(t)—impact motion acceleration, m/s. 7.2.2 Acceleration measurement by two laser interferometry methods with different measuring directions a) Ordinary laser interferometry method
The measuring direction is consistent with the moving direction, i.e., axial velocity measurement. In the fraction (4), k=a/2
Where: a——laser wavelength, m.
A typical acceleration measurement diagram is shown in Figure 1:
f+aa(t)
Moving reflector 1
Impact moving body
Calibrated accelerometer
Figure 1 Schematic diagram of acceleration measurement by ordinary laser interferometry method b) Differential grating laser interferometry method
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The measurement direction is perpendicular to the direction of movement, that is, lateral velocity measurement. In formula (4), d
k.=[m,-m2]
where: d——grating constant, m;
ml, m2--grating diffraction order.
A typical acceleration measurement diagram is shown in Figure 2:
Moving reflector
f±f(t)
Impact moving body
Calibrated velocimeter
Figure 2 Schematic diagram of acceleration measurement using differential grating laser interferometer method 7.2.3 Data processing
a) Calculate the impact displacement signal Sn(t) through the Doppler signal output by the interferometer. The phase signal of the Doppler output is:
(t)=n yuan+p(t), n=0, 1, 2, .
Where: n is the number of half cycles of the Doppler signal at the moment: p(t) is the phase of the Doppler signal at the moment t. The displacement signal is calculated using the following formula:
b) Filter the impact displacement signal to obtain S(t), perform first and second differentials to obtain the impact velocity () and impact acceleration a(t), respectively.
c) Through the impact acceleration a(t) and the output U(t) of the calibrated accelerometer, the impact acceleration peak value a is obtained. And the output voltage peak value U of the calibrated accelerometer
d) According to formula (1), calculate the impact sensitivity of the calibrated accelerometer at the calibration point i Sensitivity Sshi°e) Repeat the above a)~d) under different accelerations to obtain multiple calibrated impact acceleration values α and sensitivity values Shi, and use the least squares straight line fitting method to obtain the coefficients S and K of formula (2). f) Calculate the amplitude estimation linearity according to formula (3). 7.3 Method 2 (Velocity Change Method)
Measure the impact velocity change of the impact moving body, calculate the output integral value of the calibrated accelerometer (matching signal conditioning instrument) in the pulse 3
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duration interval, and compare the two to determine the impact sensitivity of the calibrated accelerometer. This calibration method assumes that the calibrated accelerometer is linear in the amplitude and frequency range of the calibration, and the output of the calibrated accelerometer is used as part of the calibration input data, so that the calibration result depends on the correctness of the calibrated accelerometer's response to the impact excitation and the inherent nonlinearity of the calibrated accelerometer. Therefore, the use of this method is subject to certain restrictions. 7.3.1 Principle of speed measurement
a) When the light-cutting speed measurement method is adopted, the speed measurement diagram is shown in Figure 3: photoelectric tube,
impacting moving body/
calibrated accelerometer
Figure 3 Schematic diagram of light-cutting speed measurement method
The speed change caused by the impact pulse is Aw=dlt
Where: d is the distance between the two speed measuring photoelectric sensors, m; time required for the impact moving body to pass the distance d, s. b) When a laser Doppler velocimeter is used, the velocity measurement diagram is shown in Figure 4: (t)
Impact moving body
"Accelerometer to be calibrated
Laser Doppler velocimeter
Figure 4 Schematic diagram of laser Doppler velocimeter velocity measurement is obtained from the laser Doppler velocimeter input.
7.3.2 Data processing
a) Use the integral method to calculate the area A of the voltage output of the calibrated accelerometer (matching signal conditioner) during the duration of the impact pulse.
b) Use the following formula to calculate the impact sensitivity of the calibrated accelerometer at the calibration point: Shr=A
c) Substitute the peak value U of the calibrated accelerometer output and the impact sensitivity of the corresponding point into formula (1) to calculate the peak value of the impact acceleration at the calibration point: ao
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d) Repeat the above steps a) to c) under different accelerations to obtain the impact acceleration peak value ap and sensitivity value Ssht of multiple calibrations, and use the least squares straight line fitting method to obtain the coefficients Sk and K of formula (2). e) Calculate the amplitude linearity according to formula (3). 8 Expression of calibration results
The calibration results should be reflected in the calibration certificate or calibration report. The calibration certificate or calibration report should at least include the following information:
a) Title, "Calibration Certificate" or "Calibration Report"; b) Laboratory name and address:
c) Certificate or report number, identification of each resource and total number of pages; d) Calibration unit's special calibration stamp;
e) Name and address of the unit sending the calibration;
f) Name and manufacturer of the accelerometer being calibrated, Model specification, number; g) Calibration threshold and receipt date of the calibrated accelerometer; h) Identification of the technical specification on which the calibration is based, including name and code; i) Name, factory number, accuracy/grade, certificate number, traceability and validity statement of the measurement standard used for this calibration;
i) Description of the calibration environment conditions, including: temperature, humidity, etc.; k) Description of the calibration results and their measurement uncertainty; 1) Signature, position, and issue date of the person issuing the calibration certificate or calibration report; m) Signature of the operator and verifier of the calibration test n) Statement that the calibration results are only valid for the calibrated accelerometer; 0) Statement that the certificate or report shall not be partially copied without the written approval of the laboratory. 9 The recalibration time interval
is determined by the user. The recommended recalibration time interval is 1 year. 73 Data Processing
a) Calculate the impact displacement signal Sn(t) through the Doppler signal output by the interferometer. The phase signal output by the Doppler is:
(t)=n yuan+p(t), n=0, 1, 2, .wwW.bzxz.Net
Where: n is the number of half cycles of the Doppler signal at the moment: p(t) is the phase of the Doppler signal at the moment t. The displacement signal is calculated using the following formula:
b) Filter the impact displacement signal to obtain S(t), perform first and second differentials, and obtain the impact velocity () and impact acceleration a(t) respectively.
c) Obtain the impact acceleration peak value a through the impact acceleration a(t) and the output U(t) of the calibrated accelerometer. and the output voltage peak value U
of the calibrated accelerometer; d) Calculate the shock sensitivity Sshi° of the calibrated accelerometer at the calibration point i according to formula (1); e) Repeat the above a) to d) under different accelerations to obtain the shock acceleration peak values α and the sensitivity values Shi of multiple calibrations, and use the least squares straight line fitting method to obtain the coefficients S and K of formula (2). f) Calculate the amplitude estimation linearity according to formula (3). 7.3 Method 2 (Speed Change Method)
Measure the impact velocity change of the impact moving body, calculate the output integral value of the calibrated accelerometer (matching signal conditioning instrument) in the pulse 3
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duration interval, and compare the two to determine the shock sensitivity of the calibrated accelerometer. This calibration method assumes that the amplitude and frequency range of the calibrated accelerometer are linear, and the output of the calibrated accelerometer is used as part of the calibration input data, so that the calibration result depends on the correctness of the calibrated accelerometer's response to the shock stimulus and the inherent nonlinearity of the calibrated accelerometer. Therefore, the use of this method is subject to certain restrictions. 7.3.1 Principle of velocity measurement
a) When the light-cutting velocity measurement method is adopted, the velocity measurement diagram is shown in Figure 3: Photoelectric tube,
Impacting moving body/
Accelerometer being calibrated
Figure 3 Schematic diagram of light-cutting velocity measurement method
The velocity change caused by the shock pulse is Aw=dlt
Where: d is the distance between the two velocity photoelectric sensors, m: it takes time for the impact moving body to pass the distance d, s. b) When a laser Doppler velocimeter is used, the velocity measurement diagram is shown in Figure 4: (t)
Impact moving body
"Accelerometer to be calibrated
Laser Doppler velocimeter
Figure 4 Schematic diagram of laser Doppler velocimeter velocity measurement is obtained from the laser Doppler velocimeter input.
7.3.2 Data processing
a) Use the integral method to calculate the area A of the voltage output of the calibrated accelerometer (matching signal conditioner) during the duration of the impact pulse.
b) Use the following formula to calculate the impact sensitivity of the calibrated accelerometer at the calibration point: Shr=A
c) Substitute the peak value U of the calibrated accelerometer output and the impact sensitivity of the corresponding point into formula (1) to calculate the peak value of the impact acceleration at the calibration point: ao
JJF 1153—2006
d) Repeat the above steps a) to c) under different accelerations to obtain the impact acceleration peak value ap and sensitivity value Ssht of multiple calibrations, and use the least squares straight line fitting method to obtain the coefficients Sk and K of formula (2). e) Calculate the amplitude linearity according to formula (3). 8 Expression of calibration results
The calibration results should be reflected in the calibration certificate or calibration report. The calibration certificate or calibration report should at least include the following information:
a) Title, "Calibration Certificate" or "Calibration Report"; b) Laboratory name and address:
c) Certificate or report number, identification of each resource and total number of pages; d) Calibration unit's special calibration stamp;
e) Name and address of the unit sending the calibration;
f) Name and manufacturer of the accelerometer being calibrated, Model specification, number; g) Calibration threshold and receipt date of the calibrated accelerometer; h) Identification of the technical specification on which the calibration is based, including name and code; i) Name, factory number, accuracy/grade, certificate number, traceability and validity statement of the measurement standard used for this calibration;
i) Description of the calibration environment conditions, including: temperature, humidity, etc.; k) Description of the calibration results and their measurement uncertainty; 1) Signature, position, and issue date of the person issuing the calibration certificate or calibration report; m) Signature of the operator and verifier of the calibration test n) Statement that the calibration results are only valid for the calibrated accelerometer; 0) Statement that the certificate or report shall not be partially copied without the written approval of the laboratory. 9 The recalibration time interval
is determined by the user. The recommended recalibration time interval is 1 year. 73 Data Processing
a) Calculate the impact displacement signal Sn(t) through the Doppler signal output by the interferometer. The phase signal output by the Doppler is:
(t)=n yuan+p(t), n=0, 1, 2, .
Where: n is the number of half cycles of the Doppler signal at the moment: p(t) is the phase of the Doppler signal at the moment t. The displacement signal is calculated using the following formula:
b) Filter the impact displacement signal to obtain S(t), perform first and second differentials, and obtain the impact velocity () and impact acceleration a(t) respectively.
c) Obtain the impact acceleration peak value a through the impact acceleration a(t) and the output U(t) of the calibrated accelerometer. and the output voltage peak value U
of the calibrated accelerometer; d) Calculate the shock sensitivity Sshi° of the calibrated accelerometer at the calibration point i according to formula (1); e) Repeat the above a) to d) under different accelerations to obtain the shock acceleration peak values α and the sensitivity values Shi of multiple calibrations, and use the least squares straight line fitting method to obtain the coefficients S and K of formula (2). f) Calculate the amplitude estimation linearity according to formula (3). 7.3 Method 2 (Speed Change Method)
Measure the impact velocity change of the impact moving body, calculate the output integral value of the calibrated accelerometer (matching signal conditioning instrument) in the pulse 3
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duration interval, and compare the two to determine the shock sensitivity of the calibrated accelerometer. This calibration method assumes that the amplitude and frequency range of the calibrated accelerometer are linear, and the output of the calibrated accelerometer is used as part of the calibration input data, so that the calibration result depends on the correctness of the calibrated accelerometer's response to the shock stimulus and the inherent nonlinearity of the calibrated accelerometer. Therefore, the use of this method is subject to certain restrictions. 7.3.1 Principle of velocity measurement
a) When the light-cutting velocity measurement method is adopted, the velocity measurement diagram is shown in Figure 3: Photoelectric tube,
Impacting moving body/
Accelerometer being calibrated
Figure 3 Schematic diagram of light-cutting velocity measurement method
The velocity change caused by the shock pulse is Aw=dlt
Where: d is the distance between the two velocity photoelectric sensors, m: it takes time for the impact moving body to pass the distance d, s. b) When a laser Doppler velocimeter is used, the velocity measurement diagram is shown in Figure 4: (t)
Impact moving body
"Accelerometer to be calibrated
Laser Doppler velocimeter
Figure 4 Schematic diagram of laser Doppler velocimeter velocity measurement is obtained from the laser Doppler velocimeter input.
7.3.2 Data processing
a) Use the integral method to calculate the area A of the voltage output of the calibrated accelerometer (matching signal conditioner) during the duration of the impact pulse.
b) Use the following formula to calculate the impact sensitivity of the calibrated accelerometer at the calibration point: Shr=A
c) Substitute the peak value U of the calibrated accelerometer output and the impact sensitivity of the corresponding point into formula (1) to calculate the peak value of the impact acceleration at the calibration point: ao
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d) Repeat the above steps a) to c) under different accelerations to obtain the impact acceleration peak value ap and sensitivity value Ssht of multiple calibrations, and use the least squares straight line fitting method to obtain the coefficients Sk and K of formula (2). e) Calculate the amplitude linearity according to formula (3). 8 Expression of calibration results
The calibration results should be reflected in the calibration certificate or calibration report. The calibration certificate or calibration report should at least include the following information:
a) Title, "Calibration Certificate" or "Calibration Report"; b) Laboratory name and address:
c) Certificate or report number, identification of each resource and total number of pages; d) Calibration unit's special calibration stamp;
e) Name and address of the unit sending the calibration;
f) Name and manufacturer of the accelerometer being calibrated, Model specification, number; g) Calibration threshold and receipt date of the calibrated accelerometer; h) Identification of the technical specification on which the calibration is based, including name and code; i) Name, factory number, accuracy/grade, certificate number, traceability and validity statement of the measurement standard used for this calibration;
i) Description of the calibration environment conditions, including: temperature, humidity, etc.; k) Description of the calibration results and their measurement uncertainty; 1) Signature, position, and issue date of the person issuing the calibration certificate or calibration report; m) Signature of the operator and verifier of the calibration test n) Statement that the calibration results are only valid for the calibrated accelerometer; 0) Statement that the certificate or report shall not be partially copied without the written approval of the laboratory. 9 The recalibration time interval
is determined by the user. The recommended recalibration time interval is 1 year. 72 Data processing
a) Use the integral method to calculate the area A of the voltage output of the calibrated accelerometer (matching signal conditioning instrument) during the duration of the shock pulse.
b) Use the following formula to calculate the shock sensitivity of the calibrated accelerometer at the calibration point: Shr=A
c) Substitute the output peak value U of the calibrated accelerometer and the shock sensitivity of the corresponding point into formula (1) to calculate the shock acceleration peak value ao of the calibration point:
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d) Repeat the above steps a) to c) under different accelerations to obtain the shock acceleration peak value ap and sensitivity value Ssht of multiple calibrations, and use the least squares straight line fitting method to obtain the coefficients Sk and K of formula (2). e) Calculate the amplitude linearity according to formula (3). 8 Expression of calibration results
The calibration results should be reflected in the calibration certificate or calibration report. The calibration certificate or calibration report shall include at least the following information: a) Title, "Calibration Certificate" or "Calibration Report"; b) Name and address of the laboratory; c) Number of the certificate or report, identification of each document and total number of pages; d) Special calibration stamp of the calibration unit; e) Name and address of the unit sending the calibration; f) Name, manufacturer, model, specification and number of the accelerometer being calibrated; g) Calibration period and receipt date of the accelerometer being calibrated; h) Identification of the technical specification on which the calibration is based, including the name and address of the calibration unit. and code; i) Name, factory serial number, accuracy/grade, certificate number, traceability and validity statement of the measurement standard used in this calibration;
i) Description of the calibration environment conditions, including: temperature, humidity, etc.; k) Description of the calibration results and their measurement uncertainty; 1) Signature, position, and issue date of the person issuing the calibration certificate or calibration report; m) Signature of the operator and verifier of the calibration test n) Statement that the calibration results are only valid for the calibrated accelerometer; 0) Statement that no partial reproduction of the certificate or report is allowed without the written approval of the laboratory. 9 The recalibration time interval
is determined by the user, and the recommended recalibration time interval is 1 year. 72 Data processing
a) Use the integral method to calculate the area A of the voltage output of the calibrated accelerometer (matching signal conditioning instrument) during the duration of the shock pulse.
b) Use the following formula to calculate the shock sensitivity of the calibrated accelerometer at the calibration point: Shr=A
c) Substitute the output peak value U of the calibrated accelerometer and the shock sensitivity of the corresponding point into formula (1) to calculate the shock acceleration peak value ao of the calibration point:
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d) Repeat the above steps a) to c) under different accelerations to obtain the shock acceleration peak value ap and sensitivity value Ssht of multiple calibrations, and use the least squares straight line fitting method to obtain the coefficients Sk and K of formula (2). e) Calculate the amplitude linearity according to formula (3). 8 Expression of calibration results
The calibration results should be reflected in the calibration certificate or calibration report. The calibration certificate or calibration report shall include at least the following information: a) Title, "Calibration Certificate" or "Calibration Report"; b) Name and address of the laboratory; c) Number of the certificate or report, identification of each document and total number of pages; d) Special calibration stamp of the calibration unit; e) Name and address of the unit sending the calibration; f) Name, manufacturer, model, specification and number of the accelerometer being calibrated; g) Calibration period and receipt date of the accelerometer being calibrated; h) Identification of the technical specification on which the calibration is based, including the name and address of the calibration unit. and code; i) Name, factory serial number, accuracy/grade, certificate number, traceability and validity statement of the measurement standard used in this calibration;
i) Description of the calibration environment conditions, including: temperature, humidity, etc.; k) Description of the calibration results and their measurement uncertainty; 1) Signature, position, and issue date of the person issuing the calibration certificate or calibration report; m) Signature of the operator and verifier of the calibration test n) Statement that the calibration results are only valid for the calibrated accelerometer; 0) Statement that no partial reproduction of the certificate or report is allowed without the written approval of the laboratory. 9 The recalibration time interval
is determined by the user, and the recommended recalibration time interval is 1 year. 7
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