Research On Mechanical Behavior Of Carbon Fiber Composite Laminates In Thermal Environment

Advanced composite materials,such as carbon fiber reinforced composite materials,are gradually being used in some important fields such as aerospace due to their advantages of higher specific strength,higher specific modulus,and good designability.However,during the molding process of the fiber-reinforced composite material,defects will occur inside the structure,resulting in deterioration of the mechanical properties of the material.Therefore,the research on the mechanical properties of the new carbon fiber reinforced composite materials will promote the application progress of the materials into the aerospace,meet the demand for higher performance materials in the aerospace field and is of great significance to the development of my country's aerospace industry and other industrial fields.This paper takes T800 carbon fiber/epoxy composite material as the main object,using a combination of test and numerical simulation to study its mechanical behavior and failure behavior at different temperatures,and proposes a damage evolution model of twill weave composite laminate considering the effect of temperature.Firstly,this paper summarized the international experimental method and theoretical research on the strength and stiffness of composite materials.The research achievements related to 2D woven composite laminate were mainly introduced,including the mechanical properties test method of woven composite laminate,geometric modeling of representative volume element(RVE)and damage evolution model suitable for woven composite laminate.Secondly,the test work on the strength,stiffness and damage form of T800 carbon fiber/epoxy resin laminates was carried out in this paper.The static mechanical properties of the materials were tested according to the relevant test standards,to explore the changes of the mechanical properties of the materials under different temperature environments,and to analyze the dispersion of the mechanical properties of the materials.Thirdly,the damage initiation and propagation criteria of fiber yarn and matrix are proposed respectively based on the improved three-dimensional Hashin criterion and parabolic yield criterion.According to different failure modes of fiber bundles,six damage variables of fiber bundles were determined,and a single damage variable was introduced for isotropic matrix materials.The damage evolution equations of two different materials are determined,and temperature variables were added to the model to establish a damage evolution model considering the influence of temperature.Finally,a representative volume element(RVE)model is extracted based on the structural characteristics of the actual twill weave laminate,and periodic boundary conditions are applied to it to represent the macroscopic mechanical properties of the laminate.A subroutine UMAT was programmed to perform the numerical calculations.