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Method and device for measuring compression coefficient and expansion coefficient of material on line

A technology of expansion coefficient and compression coefficient, which is applied in the field of material thermodynamic performance testing, can solve problems such as interference with normal use or production, failure to guarantee restoration to the original state, and difficult test conditions

Inactive Publication Date: 2014-01-08
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

On the one hand, sampling during use or production may interfere with normal use or production, and recovery to the original state cannot be guaranteed; on the other hand, offline sample test conditions are not easy to be completely consistent with actual working conditions

Method used

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  • Method and device for measuring compression coefficient and expansion coefficient of material on line
  • Method and device for measuring compression coefficient and expansion coefficient of material on line
  • Method and device for measuring compression coefficient and expansion coefficient of material on line

Examples

Experimental program
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Effect test

Embodiment example 1

[0024] Implementation Case 1: Application figure 1 The schematic experimental device, change the temperature under the same pressure (60MPa), test the specific volume-ultrasonic sound velocity curve of polycarbonate (PC), such as Figure 4 As shown, is monotonic. Change the pressure, apply the device to get the lnv-T curve ( Figure 5 ), the slope of each point under different pressures is the coefficient of thermal expansion, such as Figure 7 ; Change the temperature and apply the device to obtain the lnv-P curve ( Image 6 ), the slope of each point at different temperatures is the isothermal compressibility coefficient, such as Figure 8 . In this way, the on-line detection of the ultrasonic sound velocity can obtain the specific volume, and then the expansion coefficient and compression coefficient can be obtained. Figure 9 The curves of polycarbonate thermal expansion coefficient α and ultrasonic sound velocity to temperature derivative under certain pressure are g...

Embodiment example 2

[0025] Implementation Case 2: Application figure 1 The illustrated experimental device obtains the relationship between the specific volume of polycarbonate and T, P, and the regression is the Tait equation of state:

[0026]

[0027]

[0028]

[0029] In the formula: v sp — specific volume, v sp0 —Specific volume under normal pressure, C — constant 0.0894, T tr —transition temperature at atmospheric pressure, b 1 ~b 4 -constant.

[0030] Fit the above three formulas step by step to obtain the constant value, b 1 =0.99996, b 2 =0.00089,b 3 =53.47053, b 4 =-0.00138. According to the definition of thermal expansion coefficient (α) and isothermal compression coefficient (β), the expressions of α and β can be obtained:

[0031] ,

[0032] In this way, the thermal expansion coefficient and isothermal compression coefficient can be obtained from the state equation, such as Figure 10 and 11 .

[0033] Of course, if the ultrasonic sound velocity is de...

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Abstract

The invention relates to a method and a device for measuring and representing the compression coefficient and the expansion coefficient of a material on line. A temperature sensor, a pressure sensor and an ultrasonic probe are respectively arranged on one cross section of a closed material cavity of a pressure-volume-temperature (PVT) calibration device and are used for testing the volume, the temperature T, the pressure P and ultrasonic signals of the closed material synchronously. The sound velocity of the ultrasonic wave, which passes through the material with the thickness l in the material cavity is c=l / delta t within the propagation time delta t; the temperature is maintained constant, and the pressure measurement volume is changed, so that a constant temperature compression coefficient can be obtained; the pressure is maintained constant, and the temperature measurement volume is changed, so that a constant pressure expansion coefficient can be obtained; a material specific volume, a compression coefficient or expansion coefficient and sound velocity correspondence curve is established, and a corresponding equation is obtained by regression; or the compression coefficient (alpha) and the expansion coefficient (beta) can be obtained by the specific volume curve or the state equation. At certain temperature and under certain pressure, the propagation velocity of the ultrasonic wave in the material can be tested on line, and the compression coefficient and the expansion coefficient at the temperature and under the pressure can be obtained by the established corresponding curve or corresponding equation. The method has the advantages of being lossless and being easy in online representation, and the device is simple and convenient to install.

Description

technical field [0001] The invention belongs to the field of material thermodynamic performance testing, in particular to a testing method and device for on-line characterizing the compression coefficient and expansion coefficient of materials. Background technique [0002] The coefficient of compression and expansion of a material is the property of the volume change of the material after being subjected to heat and force. It is very important to quickly detect it for the accurate design and selection of molds, jigs, processing and molding machinery, and to determine the processing conditions, especially without disassembly, that is, it is required to be able to detect it online when it is continuously used or the dimensional change is effectively controlled during the production process. performance. [0003] The existing detection method of material compression coefficient and expansion coefficient is to conduct off-line measurement of its size or volume. On the one han...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N29/07
Inventor 王克俭
Owner BEIJING UNIV OF CHEM TECH
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