Estimation method of equivalent thermal conductivity of unidirectional fiber toughened composites based on gap defect identification

Abstract

The invention discloses a method for pre-estimating an equivalent thermal conductivity of an unidirectional fiber toughening composite material based on gap defect identification, wherein the method mainly comprises the following steps: processing a material micro electron microscope image by using a picture identification technology, and identifying material internal structure characteristics and gap defects; according to a fiber volume fraction ratio stability criterion, applying a geometric reconstruction technology, establishing a representative element geometric topology model, and simultaneously determining the gap defects; through a method of adding a thermal contact resistance at a representative element internal interface, introducing influence of the gap defects; and simulating to obtain the equivalent thermal conductivity by using an finite element method. According to the method, the representative element considering the gap defects is established based on image identification of an actual micro structure, and calculation of the equivalent thermal conductivity is carried out, an influence rule of gap defect position, number, thickness and other characteristic parameters on the equivalent thermal conductivity is analyzed, and a technical reference is provided for high precision pre-estimation of the thermal conductivity of same-type composite materials.

Description

technical field [0001] The invention relates to a method for estimating the equivalent thermal conductivity of unidirectional fiber toughened composite materials based on gap defect identification, which is mainly used to study the effect of gap defects around fiber filaments in unidirectional fiber toughened composite materials on the equivalent thermal conductivity of materials The influence belongs to the technical field of engineering thermophysics. Background technique [0002] In recent years, with the continuous expansion of the application field of composite materials, the research on the properties of composite materials, such as Equivalent Thermal Conductivity (Equivalent Thermal Conductivity, ETC), elastic modulus, etc., has also been paid more and more attention. , reliability and lifetime estimation provide important support. Since there are many types of additive phases in composite materials, and the bonding modes with the matrix are also very different, the ...

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Problems solved by technology

However, in the above studies, gap defects are usually simplified into a thin layer structure that completely surrounds fibers, and then the equivalent thermal conductivity of gap defects is adjusted to reflect the impact of changes in the gap ratio. Although such an operation can be introduced into the ETC calculation The influence of gap defects, but this assumption is difficult to reflect the influence of the position of gap defects on the one hand, and on the other hand, it will lead to deviations in heat transfer from the actual situation, resulting in deviations in ETC estimation

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