SJ 2317-1983 Measurement method of elastic modulus and loss factor of loudspeaker pulp SJ2317-1983 standard download decompression password: www.bzxz.net

Standard SJ2317-83 of the Ministry of Electronics Industry of the People's Republic of China
Measurement method of elastic modulus and loss factor of loudspeaker pulp (temporary)
Published on March 1, 1983
Implemented on October 1, 1983
Approved by the Ministry of Electronics Industry of the People's Republic of China Standard SJ2317-83 of the Ministry of Electronics Industry of the People's Republic of China
Measurement method of elastic modulus and loss factor of loudspeaker pulp (temporary)
This standard applies to the measurement of elastic modulus and loss factor of pulp used in manufacturing loudspeaker cones. Measurement principle
Under steady-state vibration conditions, a phase shift is introduced between stress and strain, and the elastic modulus becomes a composite quantity, called complex elastic modulus.
E*-E+jE
Where: E*—complex elastic modulus:
E Elastic modulus:
E Loss modulus:
Complex elastic modulus is also often expressed as
E*=E(1+j6)
Where: 8=.
E=tgo is the loss factor
limE*=E
2 Measurement method
2.1 Elastic modulus measurement
The phase relationship between E'E*E
The elastic modulus of paper is measured by the "vibration method of circular plates fixed on all sides". The sample is a circular plate fixed on all sides. When the sample is stimulated to vibrate by a signal source (sound source), it exhibits resonances of different modes as the frequency increases. The vibration signal is picked up by a vibration pickup and converted into an electrical signal, which is then amplified by an amplifier and recorded by a level recorder. The eigenvalue f is obtained from the curve. 1. According to the formula: 0.467t
p(i-μ2)
Published by the Ministry of Electronics Industry of the People's Republic of China on March 1, 1983, implemented on October 1, 1983
, the elastic modulus can be obtained.
SJ2317—83
In the formula: t-thickness of circular diaphragm (cm); R-radius of circular diaphragm (cm):
p-density of diaphragm (g/cm\):
μPoisson's ratio, take 0.3
E-elastic modulus (dyn/cm)
Loss factor measurement
The loss factor of paper is measured using the rate response method. B
Frequency response curve of sample vibration
From the frequency response curve recorded by the level recorder, find the nth resonance frequency fn, Afn=f2-f, corresponding to the difference between the two frequencies at the half-power point of the Ⅱth resonance frequency fn, Afn
3 Block diagram of measurement equipment and measurement environment
3.1 Equipment
(1) Audio signal generator;
(2) Microphone amplifier
(3) Level recorder;
(4) Digital frequency meter:
(5) Sound source:
(6) Fixture:
Φ200mm speaker box.
Outer diameter 70mm
Inner diameter 40mm.
（7）Capacitive vibration pickup: It is composed of a capacitive probe and an electrode to form a capacitive transducer connected to the cathode output device to pick up the vibration signal. 2
（8）Cathode output device;
(9)Physical balance;
（10）Paper thickness gauge:
（11）Paper cutter.
Measurement block diagram
Noque signal
Sound generator
3.3 Measurement environment
Temperature 20±2℃
Relative concentration
Requirements for sample
63~67%
SJ2317—83
Sensitivity 0.01g.
Graduation value 0.001cm.
Condensation electrode
Imager
Capacitor pickup and limit output
Microphone
Amplifier
Paper is made of interwoven fibers. It is not easy to make paper uniform in terms of thickness and density, which will inevitably affect the measurement results. Experiments have shown that thicker paper has better consistency than thin paper. 5 Preparation of samples
5.1 The sampling and beating of pulp physical properties are carried out in accordance with the standards of the Ministry of Light Industry QB140-61. However, according to the special requirements of the speaker, the beating degree is 20°SR for sulfite pulp: 20°SR and 60°SR for sulfate pulp. The paper is made according to the square meter weight of 200g/m\. The unevenness of the thickness of the paper should not exceed 5%. To make the sample of the beating curve, starting from the original pulp, take samples at intervals of 5°SR, and copy the sulfite pulp to 45°SR and the sulfate pulp to 60°SR.
5.2 Cut the following two samples from the copied sample, a round piece with a diameter of 70mm and a square piece with a diameter of 70×70mm.
5.3 Paste an aluminum foil with a thickness of 4~6m and a diameter of 6mm in the center of the round piece, as shown in the figure. The aluminum foil in the center is used as an electrode, and the extended extension part (width of 1~2mm) is used for grounding during measurement. 3
6 Measurement steps and calculations
6.1 Measurement steps
SJ2317—83
6.1.1 Use a physical balance to weigh the weight G of the square paper. 6.1.2 Use a paper thickness gauge to measure the thickness of the square paper and take five points from different parts to calculate the average value. 6.1.3 Connect the test device according to the block diagram. bzxZ.net
6.1.4 Feed the signal from the audio signal source to the sound source to excite the vibration of the diaphragm to be tested.
Figure 4 Sample diagram
6.1.5 Read the intrinsic frequency f directly from the digital frequency meter. 1-As the frequency of the signal source gradually increases from low to high, the frequency corresponding to the first maximum value displayed on the microphone amplifier head is f. 1.6.1.6 Read the frequency f and f2 at the half-power point (-3dB) corresponding to f directly from the microphone amplifier head.
Read the frequency with a digital frequency meter.
6.2 Calculate
Diaphragm density
Wherein: G-weight of diaphragm
V-volume of diaphragm
S-area of ​​diaphragm
t-thickness of diaphragm
6.2.2 According to f. 1-
(g/em°)
(cm2):
(cm\):
(cm).
/E/p (1-μ*)
(fa\)(dyn/em*)
Elastic modulus E=4.173pR
Afor-fa-f
6.2.3 Loss factor 8=
The calculation results of elastic modulus and loss factor must be accurate to three decimal places. 7 Sources of error
7.1 Non-uniformity of thickness and density of the copy sheet. 7, 2 During measurement, the ambient temperature and humidity must be kept constant, otherwise it will cause certain errors in the measurement results. 7.3 Systematic errors and measurement errors caused by measuring equipment and instruments. 7.4 Others.
Attached reference diagram of fixture device
SJ2317-—83
Fixture device diagram
(refer to old parts)
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