PSI - Issue 52

Haseung Lee et al. / Procedia Structural Integrity 52 (2024) 252–258 Haseung Lee, Hyunbum Park / Structural Integrity Procedia 00 (2019) 000 – 000

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This study implemented the intra and inter voids in the glass fiber/epoxy composite with RVE under the assumption as a spherical form with 40~200 μm diameter by Hsu D and Uhl K(1987) for ease of analysis and due to the limit of analysis program, and proceeded the analysis.

Table 1. Matrix property.

Value

Units MPa

Young’s modulus

4000

Poisson ration Tensile Strength Compressive strength

0.33 50.419 54.737 46.807

MPa MPa MPa

Shear strength

Table 2. Fiber property.

Value 60128 64663 4942.2 0.13933 0.17416 1161.7 441.15

Units MPa MPa MPa

Axial Young’s modulus In-plane Young’s modulus Transverse shear modulus In-plane Poisson ration Transverse Poisson ration Tensile Strength

MPa MPa

Compressive strength

This study applied the composite being made up of UD glass fiber and epoxy. Table 1 and Table2 is the mechanical property of matrix and fiber. Most of the table used the similar values in Digimat were applied to the damage related material property. The laminate was stacked up with quasi isotropic [45/0/-45/90] 2 S . It was assumed that the fiber volume ratio is 0.61 and the matrix is isotropic material. The commercial program, Digimat, was applied to predict material property with a multiscale model. The mean field homogenization method is one that predicts mechanical property by using anisotropic matrix material properties to enable contraction and transformation prediction. It was applied the Mori-Tanaka method that generally shows good results for composites and is widely used by Xu K and Qian X(2014). The Mori-Tanaka method is a field approximation based on Eshelby's elastic solution for inhomogeneity in an infinite medium. It is assumed that the average strain acting on the matrix region, which is frequently used as a micromechanical mean force, affects the strain of the reinforcement and voids. By substituting this into the relational expression and averaged basis of macroscopic and microscopic judgment and deformation, it is possible to equalize the properties of the entire composite material through intensive tensorization and uniformity of judgment and deformation. 2.2. Numerical Model For the numerical model in this study, it was used the Hanshin 2D criteria. In this paper, four failure modes were considered: fiber tensile failure mode, fiber compressive failure mode, matrix tensile failure mode, and matrix compressive failure mode. The determination formula for the four failure modes is as follows. Fiber tensile failure: ℱ ( ) = 12 1 2 + 12 2 2 11 ≥ 0,0 ℎ (1)