CN-116227034-B - Macro-micro mechanical property parameter prediction method for three-dimensional braided composite material

Abstract

The invention discloses a macro-fine mechanical property parameter prediction method of a three-dimensional braided composite material, which is based on an internal real braided structure of a three-dimensional four-way braided composite material, divides the whole material into a surface area and an internal area, respectively establishes periodic unit finite element models of the two areas, takes nonlinear mechanical behavior characteristics of a matrix material and a yarn material into consideration, develops explicit dynamics calculation of unit under different strain rates, predicts mechanical property parameters of the composite material under different strain rates, and carries out curve fitting on the mechanical property parameters under each strain rate to obtain strain rate strengthening parameters. And substituting the mechanical performance parameters and the strain rate strengthening parameters of the surface cell and the inner cell region calculated by the microscopic scale into the surface cell region and the inner cell region of the macroscopic finite element model respectively, so that the calculation of high strain rate conditions related to impact dynamics such as ballistic impact, bird strike, ice strike and the like can be carried out.

Inventors

• ZHAO ZIHAO
• LIU LULU
• ZHU XINYING
• LUO GANG
• ZHAO ZHENHUA

Assignees

• 南京航空航天大学

Dates

Publication Date

20260512

Application Date

20230308

Claims (1)

1. 1. The macro-micro mechanical property parameter prediction method of the three-dimensional braided composite material is characterized by comprising the following steps of: (1) According to the internal braiding structure and the fiber volume fraction of the three-dimensional four-way braiding composite material, carrying out parameterization modeling of unit cells, and respectively establishing an internal cell model and a facial cell model; (2) Establishing a microscopic layer finite element model based on the unit cell model established in the step (1) and applying a displacement periodic boundary condition, wherein a substrate adopts a cinnabar-king-Tang Dengwen nonlinear viscoelastic constitutive material model, a fiber bundle adopts a transverse isotropic continuous damage material model established based on Hashin failure criteria, and an explicit dynamics method is adopted to apply the same strain quantity to the unit cell in different durations to calculate so as to obtain a calculation result of the periodic unit cell; , In the formula, And The method comprises the steps of respectively obtaining the overall average strain and the overall average stress of the unit cell, wherein S is an average flexibility matrix, and obtaining mechanical performance parameters of the unit cell in all directions under different strain rates through application of displacement boundary conditions in different directions; (3) Based on the calculation result of periodic unit cells in the step (2), obtaining each modulus and strength of materials in a cell area and an inner cell area under different strain rates, and performing curve fitting on relevant strain rate strengthening parameters by a strain rate strengthening effect parameter calculation method provided in a macroscopic continuous medium model to determine parameter values; The strain rate strengthening effect formula of the material strength is as follows , In the middle of In order to achieve an initial strain rate, For strength at the initial strain rate state, In order to calculate the strain rate actually used in the calculation, To correspond to the modulus value of the material at the strain rate, Is a strain rate effect parameter of the strength; the strain rate effect formula of modulus in the material model is as follows , The specific expression form of each item in the formula is , , , In the middle of In order to achieve an initial strain rate, As the value of the initial modulus, In order to calculate the strain rate actually used in the calculation, To correspond to the modulus value of the material at the strain rate, 、 、 、 、 、 Respectively the elastic modulus and the shearing modulus value of the material in different directions, E is the elastic modulus, G is the shearing modulus, 、 、 Is a strain rate effect parameter of different moduli of the material, Respectively calculating strain rates of the materials in different directions; Taking the modulus and the strength of the material under different strain rates obtained by periodic unit cell calculation in the step (2) as iteration data points, and respectively carrying out iterative calculation on the modulus and the strength strain rate strengthening parameters in the three-dimensional woven composite material macroscopic continuous damage model; (4) Substituting the mechanical property parameter value and the strain rate related parameter value obtained in the step (3) into a three-dimensional woven composite material homogenizing macroscopic model, applying periodic boundary conditions to the model to perform calculation, extracting an integral stress-strain curve, and comparing the integral stress-strain curve with a single cell model calculation result to determine the reliability of the mechanical property prediction method; (5) And carrying out macroscopic finite element modeling on the three-dimensional braided composite material flat plate in a zoning way, carrying out high-speed impact simulation of the ice hockey through the finite element model, and carrying out a test of the ice hockey impact three-dimensional braided composite material flat plate to verify a prediction method.

Description

Macro-micro mechanical property parameter prediction method for three-dimensional braided composite material Technical Field The invention belongs to the field of aviation structural strength and safety design, and relates to a method for predicting mechanical property parameters of a three-dimensional braided composite material used in safety design of structural members such as an aero-engine blade, a casing and the like. Background Due to the urgent need for high performance composite materials in the aerospace field, three-dimensional braiding technology has rapidly evolved since the eighties of the 20 th century. The three-dimensional weaving technology firstly weaves the reinforcing fibers in the components into a three-dimensional integral fabric (preformed body), then adopts Resin Transfer Molding (RTM) to inject resin as a matrix for compound curing, and has the advantages that the three-dimensional weaving technology has the same weaving structure in the thickness direction of the material, and compared with the traditional laminated composite material, the three-dimensional weaving technology has no layering property, so that the material has good impact resistance in the thickness direction and does not have layering damage. Meanwhile, the method of braiding enables the material to be directly braided into a prefabricated body according to the size and shape of the part, so that integral braiding is realized, and meanwhile, the material can maintain the equilibrium under the condition that the material guarantees the required shape, so that the method is suitable for batch manufacturing of complex structural members such as wide chord fan blades of aeroengines. The three-dimensional braiding technology has strong designability, and the properties of the material in a certain direction can be changed through reasonably designed braiding process including braiding angle, pattern section height, fiber volume fraction and other process parameters, so that the mechanical properties and other properties of the three-dimensional braiding composite material can be adjusted. The three-dimensional braided composite material is heterogeneous and anisotropic, and the internal braided structure is complex, so that the mechanical performance parameters of the three-dimensional braided composite material are generally difficult to predict. The accuracy of the microscopic scale model in impact simulation of the composite material is relatively high, but the units are more, the model is complex, the calculation cost is high, and the time is long, while the calculation cost of the macroscopic scale model in the simulation is low, the model is easy to build, but the composite material has anisotropy and nonuniform inside, so the accuracy is relatively poor. In addition, since three-dimensional woven composite materials are used in the field of aviation, such as structural members of aircraft engine blades, cases, and the like, they are often also subjected to impact loading threats, such as bird/ice strikes, foreign object damage, blade loss, and the like. Under impact load, the composite material is in a high strain rate state, and the mechanical properties such as modulus, strength and the like are greatly different from those under quasi-static state, but the strain rate effect of the material under impact load cannot be effectively considered by the existing macro-micro analysis method, so that an impact resistance analysis method of a three-dimensional woven composite material structure, which has high calculation efficiency and precision and can consider the strain rate effect, is needed, and the analysis basis of the impact resistance analysis method is a macro-micro mechanical property parameter prediction method considering the strain rate effect. Disclosure of Invention Aiming at the defects, the invention provides a macro-micro mechanical property parameter prediction method of a three-dimensional braided composite material, which aims to solve the problems that the analysis error is large and the design work of an engine blade and a casing is difficult to effectively guide due to inaccurate description of mechanical behavior and failure of the three-dimensional braided composite material during impact resistance analysis. The technical scheme adopted by the method for predicting macro-micro mechanical property parameters of the three-dimensional braided composite material comprises the following steps of: (1) According to the internal braiding structure and the fiber volume fraction of the three-dimensional four-way braiding composite material, carrying out parameterization modeling of unit cells, and respectively establishing an internal cell model and a facial cell model; (2) Establishing a microscopic layer finite element model based on the unit cell model established in the step (1) and applying a displacement periodic boundary condition, wherein a substrate adopts a cinnabar-king-Tang Dengwen nonl