Research On The Test Method Of Thermophysical Properties Of Solid Materials

The research on the test methods of materials' thermophysical parameters and the design of their system devices have developed into an independent basic subject,which is an indispensable part of studying the basic properties of materials.With the development of material science and the progress of manufacturing technology,the types of composite materials are becoming more and more diversified.The rapid and accurate acquisition of thermophysical parameters of new composite materials is the basis for the wide application of materials in industrial production.The thermophysical parameters of composite materials are both isotropic and anisotropic.In this paper,a multi-dimensional thermostatic boundary method is developed to measure both isotropic materials and obtain the thermophysical parameters of orthotropic materials in three dimensions through one measurement.At the same time,an improved parallel hot-wire method is proposed to verify the results of multi-dimensional thermostatic boundary method.The multi-dimensional thermostatic boundary method is used to establish the mathematical equation of temperature rise suitable for isotropic and orthotropic materials by using the product solution method.The random conjugate gradient method combined with software programming are used to calculate the thermal diffusion coefficient and other parameters of materials.According to the principle of the test,the thermostatic temperature water bath heating test system is built.This system mainly includes thermostatic water bath device,sample fixed device and temperature acquisition system.The improved parallel hot-wire method modifies the traditional parallel hot-wire method through the principle of mirror heat source to obtain a new mathematical model of temperature rise.The feasibility of the model is verified by the FLUENT software simulation,and a set of test system of solid materials thermophysical property under the action of line heat source in vacuum environment is established.Two test methods are proposed to test and analyze isotropic materials such as acrylic plate,borosilicate glass and marble.The test value of thermal conductivity compared with the references values,the maximum relative deviation of the multi-dimensional thermostatic boundary method is 3.72%of the borosilicate glass,and the maximum relative deviation of the improved parallel hotline method is 2.30%of the marble,which verifies the feasibility of the two test methods and the measurement accuracy of the test system.Finally,the multi-dimensional thermostatic boundary method is used to measure the main thermophysical parameters of unidirectional carbon fiberboard of orthotropic materials,and the improved parallel hot-wire method is used to measure the thermal diffusivity and other parameters in the thickness direction.The measured values are compared with each other,the maximum relative deviation is 3.66%of the thermal diffusivity,which effectively verifies the accuracy of the multi-dimensional thermophysical boundary method in measuring the thermophysical parameters of orthotropic materials with low thermal conductivity.Figure[44]Table[15]Reference[82].