Method for forecasting thermoelasticity valid attribute and local field of composite material

Abstract

The invention provides a method for forecasting thermoelasticity valid attribute and local field of a composite material. The method comprises the following steps: acquiring the sum of Helmholtz free energies stored in all unit cells by using heterogeneous and periodically-distributed microstructure of the composite material as a study object; converting thermoelasticity analysis and solution problem into the problem of minimizing-acquiring stationary value in an energy equation under a restricted condition; performing variational analysis for the energy equation to obtain an Euler-Lagrange equation set for solving a wave function and corresponding inhomogeneous boundary conditions; rewriting the energy equation into a discrete form by the numerical analysis technology-finite element method; solving to obtain the density of Helmholtz free energies of the unit cells; applying a constitutive model using the density as an effective medium to the composite material; then changing the load and temperature conditions of the composite material to analyze the local field of the composite material. The method is high in practicability, high in universality, and can obviously raise the calculating speed and efficiency for such problems.

Description

technical field [0001] The invention relates to the field of material mechanical performance analysis, in particular to a method for predicting the thermoelastic effective properties and local fields of composite materials. Background technique [0002] Many composite materials are used in temperature-sensitive environments such as electronic packaging, thermal protection systems, etc., where accurate prediction of thermal coefficients such as thermal expansion coefficient and thermal conductivity becomes very important. The effective thermal conductivity of composite materials is affected by many parameters such as component properties, volume fraction, component distribution, and direction. Scholars from various countries have proposed various mesomechanical models to predict their effective thermal conductivity. The simplest model is based on the mixing rule assumed by Voigt and Reuss, which provides the upper and lower bounds of effective properties, but it is difficult ...

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Problems solved by technology

[0004] Aiming at the above-mentioned deficiencies in the prior art, the present invention provides an efficient and reliable composite material thermoelastic effective property and local field prediction method, which solves the low analysis efficiency and poor precision existing in the prior art, especially the local field variable distribution Deficiencies that cannot be precisely predicted

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