Method for measuring polymer-base foam material linear expansion coefficient by displacement sensor

Abstract

A method for measuring linear expansion coefficient of polymer based foam material by using displacement transducer includes fixing measurement zone of material to be measured on two pincer arms of said transducer and setting it in temperature zone of 4.2 ¿C 300 K, connecting resistance foil gauge forming Wheatstone bridge to resistance strain gauge, collecting deformation of material to be measured and clamping force on said transducer then converting displacement amount to be electric amount, sending these data to computer for obtaining curve of strain to temperature variation and furthermore to obtain expansion coefficient of material to be measured from the curve.

Description

technical field [0001] The invention relates to a method for measuring thermal expansion properties of materials, in particular to a method for measuring the linear expansion coefficient of polymer-based foam materials with a displacement sensor, which is applicable to a wide temperature range (4.2K-300K). technical background [0002] With the application and continuous development of cryogenic technology in the aerospace field, materials are required not only to have light weight, high strength and good toughness under low temperature conditions, but also to have lower thermal physical performance parameters. Therefore, studying and measuring the influence of low temperature environment on the mechanical and thermal properties of materials is an important guarantee for the rational selection of materials and safe operation of low temperature devices and components. [0003] The linear expansion coefficient of cryogenic materials is a very important physical parameter in th...

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Problems solved by technology

[0004] At present, the traditional device for measuring the linear expansion coefficient, such as the known linear expansion coefficient of quartz, can measure the linear expansion coefficient of the material with a dial gauge reading instrument, but because the end face of the polymer-based foam material is soft, the size is unstable, and it is easy to Adsorbs the inner wall of the quartz tube and is not suitable for the measurement of the linear expansion coefficient of the foam

There is another method, which is to use low temperature strain gauges to measure the coefficient of linear expansion of materials at low temperatures. Small, does not meet the measurement requirements of polymer-based foam materials

In addition, the current domestic strain gauge machine suitable for low-temperature applications is small in size and cannot cover the surface of heterogeneous materials. Therefore, only when the deformation of the specimen is uniform, the measured strain can represent the overall deformation of the specimen. Measurement of the bulk linear expansion coefficient of heterogeneous materials such as materials, polymer-based foams and welding materials, strain gauges are not suitable

In addition, many methods for measuring the linear expansion coefficient of certain types of special materials have been reported at home and abroad, such as thermal analysis, formula derivation, etc., but they are not universal, and are not suitable for measurement in extremely low temperature environments

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