GB/T 8419-1987 Earth-moving machinery driver seat vibration test methods and limits
Some standard content:
National Standard of the People's Republic of China
Earthmoving machinery
Operater seat
Vibration test method and limit values
Earthmoving machinery-Operater seat-Vibration testing method and ilmiting levels This standard refers to the international standard ISO7096-1982 Earthmoving machinery-1 Subject content and scope of application
Operater seat-
UDC621.878/879
+629. 11. 014
GB 8419-87
-Transmission of vibration
This standard specifies the method and limit values of the vibration test of the driver's seat of earthmoving machinery, which is used to evaluate the riding comfort of the driver's seat. This standard applies to the earthmoving machinery listed in Table 1. Each type of machinery has the same vibration characteristics, and other earthmoving machinery can refer to it for implementation. Table 1
Classification number
Machine name
Structural features
2 Reference standards
White-type scraper
Without suspension device or
Buffer and shock absorber
GB2298 Mechanical vibration, shock terminology 3 Definitions
3.1 Whole body vibration
Vibration transmitted to the human body through the buttocks of the sitting position. 3.2 Driver's seat
With suspension device or
Buffer and shock absorber
The component for the driver to sit on, including the seat bracket suspension system, 3.3 Frequency analysis
The method of quantitatively analyzing the vibration signal as a function of frequency. 3.4 Measurement time
The duration of obtaining vibration analysis data. 4 Symbols and meanings
-Instantaneous acceleration, m/s,
Tire loader
Tire bulldozer
Working weight greater than
5 000 kg
α/Root mean square value of acceleration in 1/3 octave bandwidth with center frequency, m/s\, ag
Frequency-weighted acceleration, m/s\;
Weighted root mean square acceleration, m/s3
Approved by the State Machinery Industry Commission on December 7, 1987 Tracked loader
Belt bulldozer
All structures
Implementation on January 1, 1989
GB 841987
aws—aw at the seat installation position, (see 7.1.2), m/s\, z on the seat pan (see 7.1.1), m/s
Bandwidth in frequency analysis, Hz;
—frequency, Hz:
Analysis time, s;
Frequency-dependent tailless weighting factor, gravity acceleration, 9.80665m/g
Mean square error or standard deviation;
"Root mean square value,
Power spectral density function , (m/s\)\/Hz; Probability density function of acceleration amplitude:
S1P Seat calibration point
Octave.
5 Instrument and calibration
Acceleration sensor
The test system connected with the acceleration sensor and amplifier shall be able to measure the RMS acceleration value with a peak factor of 6 and a dynamic range of 0.1+10m/s,
The acceleration sensor and amplifier shall be properly calibrated within the range of .8-40H2, calculated according to the instrument manual and actually measured. The relative error shall not exceed +2.5% compared with the root mean square value of the measurement. 5.1.3 The accelerometer shall be strong enough to withstand instantaneous acceleration values up to 100m/s. 5.1.4
The vibration frequency of the accelerometer shall be greater than 300Hz.5.2
Instrument calibration
The accelerometer must be calibrated in accordance with the prescribed procedures in a measurement unit approved by the national metrology administration department, and shall have a calibration certificate and a valid period of use.
The calibration method shall ensure that the calibration is within the range of 0~40Hz The relative error between the change in the sensitivity of the accelerometer and its average value is within the range of ±2.5%.
To ensure the measurement accuracy, the instrument should work within the allowable temperature and humidity range. 5.2.2 Calibration of the measuring instrument system
52.2.1 Check the signal level, terminal impedance and cable length of the measuring instrument system. 52.2.2 This standard uses the gravity field calibration method to calibrate the acceleration sensitivity of the measuring system. In the gravity field, the sensitive axis of the sensor is vertically inverted 180°, and a peak-to-peak electrical signal corresponding to 19.61 m/s2 (2g) is output. The sensitive axis of the accelerometer should be kept vertical, and the angular deviation of the inversion of 180° should be between ±4°, and the peak-to-peak change of the output voltage should be within the range of ±0.5%. 5.2.2.3 The internal electronic calibration of the instrument system should be checked before and after each test, and necessary corrections should be made to ensure the accuracy of the measurement base. 5.2.2.4 Before the test, the measurement system of the acceleration sensor and amplifier shall be balanced and zeroed to make the system in a zero output state. Before and after each test, the zeroing value of the measurement system shall be recorded. 5.3 Frequency analysis
5.3.1 This standard adopts the 1/3 octave bandwidth method to perform frequency analysis on the measurement signal. 5.3.2 Frequency weighted root mean square acceleration value
For the vibration signal directly measured by the measurement system or recorded by the tape recorder, a 1/3 octave frequency analysis shall be performed according to the center frequency given in Table 2 or Figure 1. During the analysis, the root mean square value of acceleration a in each frequency bandwidth shall be averaged within the specified analysis time T, and multiplied by the corresponding frequency weighting factor W given in Table 2 or Figure 1 to obtain the weighted root mean square acceleration value. At the same time, formula (1) shall also satisfy formula (2):
Where the shortest sampling time of T is 3005.
is the center frequency of the multiple measurement range
CB8419—87
2B,T ≥ 140
+++++++++++++++++++++( 1 )
Weighting factor WdB
0. 50 - —6 8B
0. 56 = — 5 dB
0.63=-4aB
0. 71 = -3 dB
0. 80=2 dB
0. 89——1 dH
0. 80 -—2 dB
0. 63 ± - 4 dH
0. 40= —8 dB
0.315=—10 dB
0. 25—12 dB
0. 20= -14 dB
center.16=16 dB
0.125=-18dB
0. 10=—20 dB
6 Vibration test bench
6.1 Technical requirements
3dB10ct
GB 8419—87
dB1oct
Figure 1 Weighted bearing curve along direction a
6dBDct
The vibration test bench should be able to drive the loaded driver's seat according to the specified test power spectrum. In the process of comprehensive feedback correction of the input command signal, the transmission function of the test system can be corrected to meet the requirements of PSD and PDF of axial output along α at the seat installation position. The following technical characteristics are for reference only when selecting a vibration test bench: Maximum dynamic thrust = 1.5 × mass (including the vibration table platform, seat and test person) Operating frequency range = 0. 5 ~ 20 Hz;
Table travel - 175mm (considering the zero drift of the electronic control system, the travel should be greater than 175mm). 6.2 Safety recommendations
The vibration test bench should have reliable safety protection devices. Regardless of the reason, the table acceleration exceeds 15m/s\ and can automatically shut down. The speed of the vibration test bench should be limited to 1.3m/s. 7 Test preparation
7.1 Sensor installation
7.1.1 Vibration transmitted to the driver
To pick up the vibration transmitted to the driver, the acceleration sensor should be installed in the center of a thin disk with a diameter of 210+50 mm. GB 8419 --87www.bzxz.net
The reading disc is placed between the driver's buttocks and the seat stopper when sitting. The sensor should be located between the two ischial bones, and the sensitive axis is parallel to the measuring axis α, as shown in Figure 2. The disc can be made of rigid or semi-rigid materials, as shown in Figure 3. For soft seat cushions or thicker seat cushions, semi-rigid discs are recommended. In addition, the resonance frequency of the disc should be greater than the upper limit of the test frequency.
7.1.2 Vibration of the seat installation position
To detect the vibration of the seat installation position, the acceleration sensor should be installed on the vibration table or the rigid part of the seat mounting seat.It is located within the vertical projection plane of the cushion, the distance from the longitudinal vertical plane of the cushion symmetry center should not exceed 100mm, and the sensitive axis is parallel to the measuring axis. 7.2 Test seat
7.2.1 The installation height of the seat on the vibration table should be higher than the installation height of the typical machine. Figure 2 Measurement axis (axis is the line from hip to head) +
250±50mm
(a) Rigid disk with acceleration sensor placed in the center Figure 3 Disk
GB 841987
250±50mm
Space for installing accelerometer
Install geodesic meter and increase
Body image wind adjustment disk for center measurement
(h) Semi-rigid disk made of rubber, plastic and other materials with hardness (A scale) of about 90~90 Continued Figure 3
7.2.2 The newly produced test seat should be tested for more than 5 hours. During the test, a lead pellet weight of 75kg is placed on the seat and sinusoidal vibration is input according to the resonant frequency of the seat system. If the seat has a suspension device, the amplitude should be adjusted to make the suspension system move at full stroke, but care should be taken to prevent the shock absorber from overheating.
According to the seat instructions, the driver's weight and body shape, the seat should be properly adjusted to put the driver in the best riding state. 7.3 Test persons.
7.3.1 The random vibration test requires two test persons of different weights. The total mass of one test person is 55kg (-0% to +10%), of which the mass of the weight belt tied around the waist shall not exceed 5kg; the total mass of the other test person is 98kg (-0% to +10%), of which the mass of the weight belt tied around the waist shall not exceed 8kg. If the total mass of the test person does not meet the requirement of 98kg (-0% to +10%), a person with a slightly lighter mass may be selected and appropriate weight may be added to make the total mass reach 98kg (-0% to +10%), but the weight shall not exceed 15kg. The weight shall be evenly distributed between the belt and the protective clothing (or vest), and the details of the weight shall be recorded in the report. At this time, the test result obtained according to 9.2 should be less than 95% of the limit value in 10.2, otherwise it is invalid.
7.3.2 The test person should sit naturally on the seat, put his feet on the pedals, and put his hands flat on his knees. If there is a simulated steering wheel on the test bench, its layout should be typical, and the test person's hands should also be placed on the steering wheel according to the operating specifications. The test person should be specially trained to ensure that he is always in a passive state relative to the seat during the entire test. Vibration characteristics of test input
Table 1 shows four types of machinery, and the vibration characteristics of each type of machinery are described by the corresponding acceleration power spectrum density function. 8.1 Acceleration power spectral density function
PSD = 5.30[HP2]. ;LP211
PSD,=2.72HP|LP2\
PSI), = 1.11/HP24:2.11LP,12PSD, = 0.79|HP12 3 |LP1
Wherein: PSD, represents the acceleration power spectral density function of the first category machinery, 1=1,2.3,4(LP,) =
(LP) =
1 + 1.414s + $2
·（3)
1+1.414S+sz
GB 8419—87
(LP) =
1+2.6135+3.41452+2:61353+5
1+2.613+3.414S*+2.6135*+S
f. —Filter cutoff frequency, Hz. See Table 3. Table 3
Mechanical classification number
Note HP and IL.P refer to Bodegas high-pass and low-pass filters, and the subscript is the slope of the filter, decibel/times. According to the cutoff frequency and slope, the bandpass filter can be determined. The acceleration power spectrum density function curves are shown in Figures 4 to 7. da5r
Figure 1 PSD curve of the first category of machinery
ZH/h,s/a)'aSd
Figure 5 PSD curve of the second category of machinery
GB 8419-87
PSD curve of the third category of machinery
Figure 7 PSD curve of the fourth category of machinery
8.2 Table 4 specifies the tolerances of the vibration level and power spectral density function of the test input Table 4
Machinery classification number
Root mean square value
Weighted root mean square value
Indicator, m/Tolerance
Tolerance of input PSD curve
1.5~2.5Hz±1dB
1. α~ 3. 0 Hz±2 dB
1. 5~3. 0 Hz=1 dB
1. 0~3. 5 Hz±2 dB
Minimum percentage of input RMS value within a given frequency band
1. 5~~2. 5 Hz
1. 0~-3. 0 Hz95%
1.5~3.0 Hz80%
1. 0~3. 5 Hz 95%
Mechanical classification number
Root mean square value
Weighted root mean square value
Indicator.m/s
GB8419-87
Continued Table 4
Tolerance of input PSD curve
1. 5~f. 0 Hz±1 dB
1. 0~~11. 0 Hz±2 dB
5. 0 ~11. 0 Hz= 1.dB
3. 0--13. 0 Hz±2 dB
Minimum percentage of average
root square value within a given epileptic band
1. 5~6. 0 Hz70%
1. 0~11. 0 Hz 95%
5. 0~~11. 0 Hz 80%
3. 0~13. 0 Hz95%
The first column of Table 4 represents the input root mean square acceleration reference value: the second column is the input weighted root mean square acceleration value, the third column is the tolerance of the second column, and the fourth column is the tolerance of the test input PSD curve. 8.3 Requirements for the probability density function of the test input 8.3.1 The acceleration signal shall be collected at least 50 data points per second. 8.3.2 The amplitude of the acceleration signal shall be divided into several equal parts less than 1/2a. The relative error between the probability density function and the ideal Gaussian function within ±2a shall not exceed ±20%. The collected data points shall account for at least 93% of the total data. Data exceeding 4a shall be discarded. 9 Test procedure
9.1 Damped vibration test
9.1.1 Place a lead pellet weight of 75kg on the seat and input sinusoidal vibration according to the resonant frequency of the seat system. If the resonant frequency is less than or equal to 2 Hz, input sinusoidal vibration with a bend-to-beam displacement of 50 mm; if the resonant frequency is higher than 2Hz, input sinusoidal vibration with a bend-to-peak acceleration of 7.9 m/s.
9.1.2 The test shall be repeated 3 times. In each test, the vibration signal shall be simultaneously collected by the sensors in 7.1.1 and 7.1.2. According to 5.3.2, calculate the weighted root mean square acceleration values α1. and αw at the seat cushion and the seat installation position respectively. The relative error between each test result and the arithmetic mean of three test results shall not exceed ±5%, and the test average values α1. and αw shall be recorded. 9.1.3 Maximum seat transmission rate
9.2 Random dynamic test
9.2.1 According to the provisions of 7.3 and 8, select the test person and the input power harmonic density function corresponding to the machine type. 9.2.2 For the two test persons of different qualities in 7.3, the test shall be repeated three times respectively. The measurement and calculation method is the same as that in 9.1.2. (7)
9.2. 3 During the test, if the actual input weighted root mean square acceleration value is different from the value in the second column of Table 1, the weighted root mean square acceleration value a transmitted to the test person shall be corrected: A = a ± 4 Data in the second column
10 Vibration limit
According to the seat vibration test conducted in this standard, qualified products shall meet the following dynamic indicators. 10.1 The maximum transmission rate of 9.1.3 shall not exceed 2.0. 10.2 The weighted root mean square acceleration correction value transmitted to the driver calculated in accordance with 9.2.3 shall not exceed 1.25m/s11 Test report
After completing the test, fill in the test report in the format of Table 5. (8)
Seat manufacturer
Seat type
Test date
Type of transmission device used
In this test
Maximum transmission rate
Vibration added to the driver
Velocity weighted root mean square value
Person who completed the test
(Signature)
Additional remarks:
This standard is under the jurisdiction of Tianjin Engineering Machinery Research Institute. GB 8419-87
Test run time before test, h
Height of seat calibration point from test platform
Test input machine classification number
This standard was drafted by Tianjin Engineering Machinery Research Institute. The drafters of this standard are Dai Linjun, Cao Chonghou, Qiu Yi, etc. Membrane
ua17hzan shoe road device
year effort
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