PSI - Issue 54

Xingling Luo et al. / Procedia Structural Integrity 54 (2024) 75–82 Xingling Luo et al. / Structural Integrity Procedia 00 (2023) 000–000

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Table 1. Minimum and maximum values of geometrical parameters of graphite particles in CGI (Palkanoglou et al., 2020). Volume fraction of graphite (%) Perimeter (μm) Area (μm 2 ) Major axis (μm) Minor axis (μm) 5.2-11.37 3.54-315.88 0.99-6086.96 0.602-67.96 0.52-28.51 The single-inclusion model without CZE is shown in Fig. 1a. The square domain comprises a generic graphite inclusion (nodular in this example), with dimensions based on the results of microstructural characterisation, perfectly bonded to the matrix region. The area of the unit cell was calculated to fit the average volume fraction of graphite. The bottom faces of all nodes were fully constrained, and incremental axial displacement was applied to the top face to simulate uniaxial tensile loading.

Fig. 1. Microstructure in FEA model: (a) without CZM (a); (b) with CZM.

The geometrical configuration of CZM is presented in Fig. 1b. The nodular graphite inclusion of radius 16.26 μm was embedded in the matrix domain. In this case, the graphite and matrix domains were meshed with cohesive elements to allow random crack propagation. Additionally, a layer around the inclusion was established to represent the interface between the matrix and the graphite particle. The thickness of the cohesive interface and elements was zero. The boundary and loading conditions were set to create a uniaxial stress state. The unit cell was modelled with triangular finite elements (3-node linear plane strain triangle – CPE3) as quadrilateral elements would generate sawtooth particle boundaries, causing stress concentrations (Zhang et al., 2018). Periodic boundary conditions (PBCs) at the cell’s edges were implemented in this model. All the details of the model are summarised in Table 2.

Table 2. Model details.

Volume fraction of graphite (%)

Element type

Boundary conditions

Software

Analysis type

Domain length

Mesh size

Loading

Abaqus

Dynamic explicit

0.1 mm

8.3

2 µm

Triangular (CPE3)

Tension

PBCs